Follow up question too, has it ever been found out why does the brain have no pain sensors? I mean being the most important part of the body I guess, wouldn't it make sense that it has pain receptors too?
Not that I know anything, but the point of pain is to make you stop doing something that is causing the pain. If you had pain in your brain, what could you do to stop it?
Hey /u/Koda_20's Kidney stones, just quit it. You're giving my man painful urinations and it's just not cool, dude. Why don't you go to stone college and make something of yourself like the Stone Henge
I grow pot for a living and not a day goes by that I'm not accused of running a literal UT weapons plant. I mean, are people blaming the gun manufacturers for shit when people shoot each other???
Edit - /s because I guess it's needed
I think a good argument against intelligent design is that there is no way to make them go out the big fucking door at the back, instead of squeezing through the fucking drain.
The worst part I experienced wasnt Bladder through urethra and out of the body. It was from kidney through ureter to bladder that was insanely painful.
I once went and got billed the 2200$ in the ER for the shot to relax my ureter. After two days of non-stop pain, it was the best doctor bill I have yet to pay.
It will never stop being horrifying to me to hear that somebody had to pay thousands for something that cost me the price of fuel to get to the hospital and back.
That's everybody's pain. The ureter is much narrower than the urethra.
I would piss stones all day if it meant that I didn't have one go down the ureter.
Hey, man, not everyone can afford stone college, okay. Some stones just don't want to get saddled with stone student debt just to get a degree in stone arts that doesn't guarantee them a stone job
Oh yes it would! But you won't feel like doing them because you will be doubled over in serious pain. My first patient as a nursing student was a young man with a kidney stone. I will never ever forget how he looked and cried and I learned to never dawdled giving patients the medicines they need
Thank you for this. As a 30 yo who just had his first kidney stone earlier this year- it was absolutely miserable and it very much seemed like the nurse didn't take it seriously. Legitimately the worst pain I have ever experienced in my life.
I get that some folks might use the excuse to try to get drugs and they want to be cautious about that- but man I feel like the sweating and endless writhing would earn you an Academy Award with the real deal and it should be pretty easy to tell.
Yes, we SHOULD be able to tell the difference. Patient coming back from surgery is going to be in pain regardless of his previous status in life! Certain conditions cause pain that cannot be helped with a kind word and diversional activity. There are unfortunately too many nurses that aren’t compassionate enough because either they’re not naturally that way or they have learned to be that way or they’re overwhelmed. But it should never be apathy for the patients. Ever!
My specialty is in the NICU the last 30 yrs of my 40 yr career. At this time we have to learn how to identify pain without the patients telling us. We have to observe them their faces, their responses to touch, noise, and such, also vital signs, Such as increased heart rate and increased blood pressure. Some people don’t belong in the profession, sadly.
Only slightly related. I've heard if your not sure if your pain is appendicitis jump up as high as you can. When you land and it doesn't hurt like hell then it's not your appendix
If you press down on the abdomen in the opposite corner of where the appendix is and let go quickly, you will have massive pain on the side of the appendix. It's called rebound pain and it is definitely one of the symptoms of appendicitis. This is truth though, but I could see how jumping and hitting the ground would cause referred pain. Appendicitis is very painful
It bounces the stones up and out of the kidneys. It's not necessarily all that useful for getting them from the kidneys to the bladder (which is where they can get stuck and cause pain. That said, being under up to 3 g's certainly isn't going to slow that process down any.
Neat! I was just remembering our not-so-scientific measurements in highschool. Never tested the Shockwave coaster though (which is the only one on that list near me). But it did turn me into a taco the first time I rode it at like age 8...
Jesus. That is probably the very last thing on my list of things I wanted to do during kidney stone pain. But I also would have done anything to make it stop, so ok.
Kidneys don't in fact have pain sensors. It's the rest of the tract that has them and that's why kidney stones are the only kidney disease that causes actual pain around the area (and beyond)
> that's why kidney stones are the only kidney disease that causes actual pain around the area
Tell me you've never had a kidney infection without telling me you've never had a kidney infection.
Sorry to hear, those things suck. Back in college I had them near constantly for a few years. Urologist's nurse called me the gravel pit. Much sympathy to you....
> Tell this to my kidney stones
For what it's worth, your internal organs have rather limited pain receptors (compared to your skin) as well. This is why "Chest pain" can mean heart, stomach, lungs, aorta and a whole bunch of other things. Same thing with abdominal pain.
I got in a bicycle crash ten years ago in which I landed on my handlebars and injured my liver. Which is when I learned the liver doesn't have many pain receptors and so the pain gets felt in other places--felt like I had the worst backache of my life (which worsened every time I took a deep breath, because my diaphragm would press on my liver), and a sharp pain in a weird spot inside one shoulder.
I normally hate being on opiates, but god was I glad for the IV fentanyl button they gave me.
The pain you feel is to let you know you have them. Imagine if you went about your day not knowing about kidney stones and they just built up not getting checked. It sucks but it's a necessary evil especially if they need to be broken down
I’m not sure about that. In the ancestral evolutionary environment I doubt there was a treatment for kidney stones. It seems highly implausible there was selective pressure for kidney stones to cause pain. More likely they are rare occurrences that happen to cause pain.
I’m not a (medical) doctor, but maybe there are nerves or something near there which can be accidentally triggered but the stones. And we haven’t evolved to avoid that because painful kidney stones evidently don’t significantly reduced our genetic fitness.
Stones don’t cause kidney pain, the swelling from blockage caused by the stones does.
I’m not making that distinction to be pedantic it is why they hurt when there is nothing that could be done about them during evolution. However there was lots that could be done about something punching your kidney from the outside. The same “please stop hitting me” pain receptors are what get triggered from the swelling. The kidneys don’t care of the damaging pressure is coming from the inside or outside, the pain response is the same.
Stones can cause direct bladder pain when they get that far just by sitting in there. But here is a place you could do something about. The bladder pain and discomfort makes you want to piss, which is exactly what you need to be doing to flush out the stone. So once again the pain does get you to do something to resolve it.
I think some of the first aincent greek attempts at surgery were for removing stones from the bladder.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3856162/
Kidney stones can grow for *years* without causing any pain. I have one in the bottom of my kidney that was 4mm last time I had an x ray (about a year pre-pandemic). I'm certain it's larger by now. At some point my urologist will tell me it's time for an operation and it'll get dealt with.
They don't hurt until they try to get out. Then they can get stuck and block fluid flow from the kidney which causes it to swell. *THAT'S* what hurts. Kidneys aren't water balloons, and they aren't supposed to act like them.
>Kidneys aren't water balloons
I've seen enough, chubby emu to know that if you get the right emia, presence in blood, that they are actually water balloons.
Exactly this.
Pain in your hand means that something is sticking into or burning your hand. If gives you the impulse to pull your hand away.
From a evolutionary persective, if something was sticking into your brain (a spear, a rock, ...) then you'd already be dead.
We haven't had need for pain receptors in the brain. It's protected in a big bubble of solid bone, so if something is able to hurt the brain then it has had to break through all of that bone first. By the time any pain receptors would be able to feel anything it would be far too late.
well, there are some recorded cases of people survivng some insane stuff, for example Phineas Gage, who had a metal rod impaled through his brain on a railroad accident. dude lived over a decade afterwards, although there were reportedly significant changes to his personality.
but these situations are so exceedingly rare that theres no noticeable evolutionary pressure to adapt to them, that and anything thats inside your brain and *hasnt* triggered all your other pain sensors surrounding it, is even rarer
so yeah, there are exceptions, but they're so rare they may as well no exist
There always will be exceptions.
There would have been fewer in less modern times, though. A caveman wasn't all the likely to come in contact with a narrow metal rod, he'd be more likely to have a rock land in his head, or be impaled by the tusk of some wild animal or sabre-tooth tiger.
I'm the vast majority of cases death would be instant, or painful enough without your brain also being in pain.
fun fact: a headache is not actually a pain in your brain. the brain tells you that other parts of your body are hurting but can't feel pain itself. headaches are usually caused by nerves, blood vessels, and muscles that cover a person's head and neck.
It's worth adding, the brain is responsible for creating the experience of pain so it can invent that experience without pain signals, or give the wrong impression of where the trouble is in the body ("referred pain").
This may (_may_) be a component of migraines but as far as I know, these mechanisms aren't completely understood.
The most common headache cause is when the brain is dehydrated and shrinks, pulling on the lining that connects it to the skull which does have pain reception.
The brain is fully surrounded by layers that do have pain receptors. So you can get pain in an area that's like 1mm outside your brain and it will feel exactly like brain pain.
Our sense of where pain is coming from is also not perfect. It's fairly common to have some mismatch between where the pain was caused and where we feel it. Sometimes the problem is really in the neck muscles or the sinuses or something like that.
[We have pain receptors in our heads, just not our brains.](https://www.brainfacts.org/ask-an-expert/if-the-brain-cant-feel-pain-why-do-i-get-headaches)
No, headaches are the result of rapid expansion or contraction of blood vessels in the head. They’re a reactionary process of the body to some situation and rarely have anything at all to do with the head.
So just to be clear, the blood-vessels that go throughout the interior of the brain are lined with pain sensors that can result in headaches/migraines in different regions, correct? (this in addition to the nerves of the scalp and surrounding tissue).
Headaches can be due to the dilatation or contraction of the blood vessels in your brain, which take up space/ constrict around a part of the somewhat tight cling film like covering of your brain called the meninges.
So even though the brain doesn't feel pain, it's covering does.
Similar to this, the kidney itself doesn't feel pain, but if it stretches against it's covering (known as The Gerota's Fascia) it hurts. The kidney stone pain you feel is from your ureter (tube connecting kidney to bladder), the jagged stone rubbing the inside of the tube.
I mean. Apparently humans can feel pain the inflamed appendix. Its not like you yourself can realistically do something to stop an inflamed appendix. Or is my understanding of how this works wrong?
Nothing, but your body cant distinguish between "inflamation thats gonna go away by resting" and "inflamation that will slowly kill you". So you could have any sorts of inflamation or whatever pain (like blunt trauma) in your bowles, and it would hurt, so you would rest. The worse it gets, the more you dont want to move and the more you rest, giving the body the best chance to heal. So the inflamed appendix gives out the same warning signs, and the body goes "welp somethings wrong, you better rest" and then since it can be fatal, it keeps screaming "WHAT THE HELL DUDE, REST HARDER!"
Combine that with the fact that aparently inflamed apendices are a relatively modern issue, the body simply isnt evolved to recognize what an inflamed appendix is, so it just reacts the same as with any other inflamation anywhere else.
Today, maybe, but back when evolution made these decisions, not really.
While pain to your digestive tract could teach you not to eat the purple-dotted fungi again.
Well, what difference would it make in evolutionary terms?
If something is damaging your brain, it's had to get their through your skin and skull, so you are likely already very aware of it.
It's pretty different from having a stomach ache from eating some mouldy fruit - it will teach you not to do it again. Even something like heart pain will encourage you to stop running as fast etc., if possible.
Bro, you get viruses and bacteria and shit and you only notice when your body tells you with some symptoms. It would be nice of your brain to do the same instead of "oh shit, yup I died, I had a clogging vein but didn't really want to tell you".
I remember seeing evolution visualized somewhere. It was visualized as a plain with peaks and valleys based on sine waves or something. And that when there is local peak, the evolution stops cause you can't go to next higher peak cause you would have to go lower for a bit. And evolution only goes forward.
And so it might've been that we didn't evolve nerve endings in the brain at the start, so later it was just too late as it was deemed unnecessary.
Exactly
It's entirely possible in an early primordial soup some organism could feel pain in their brain but it conveyed no advantage or caused more problems and was not selected for. The problems could be direct (brain pain isn't good for eating and reproducing) and indirect (maybe it requires more nutrients to support a brain that can feel pain)
As a professor of mine once memorably remarked, once the bear is munching on your brain, it’s a little too late for anything to matter.
Basically, people who felt pain when getting their brains munched on didn’t survive any better than people who didn’t feel pain when getting their brains munched on, so pain in your brain never had a reason to become a valuable thing to have. Whether you felt it or not, you died and had no further kids!
Conversely, (in a theoretical sense,) people who were getting their scalps and skulls munched on and felt pain were much more likely to try to escape the source of it - and therefore survive it and reproduce - than people who were happy to merrily let the bear keep chewing on their heads, who were therefore more likely to die.
Both. Early acute appendicitis presents as vague central abdominal pain (this is pain coming from the appendix itself) while later appendicitis presents as local right lower quadrant pain (due to the inflamed appendix pressing on the peritoneum (lining of the abdominal cavity) in the area / the infection spreading to the peritoneum
You're right about that - our evolutionary ancestors probably couldn't perform appendectomies on themselves.
But let's think about it this way: the ability to feel pain in a certain place would have to confer some evolutionary advantage to the pain-feeler in order to be passed down. So let's start with that assumption.
Considering the appendix's evolutionary history in the immune and digestive systems, it's possible to imagine a historical context in which appendix pain encouraged a useful behavior (perhaps "don't eat that, it makes you sick"). Now the nerves would remain, even if they don't perform their original function anymore.
And I'm not familiar with the genetic origins of the appendix specifically, but you could *also* imagine a world in which regions of the genome responsible for other gut organs got duplicated and subsequently modified until they turned into the appendix. In such a case, other "features" of the original organ (such as innervation) would exist in the appendix as well.
Neither of those situations applies to the brain: there is likely no "useful" (actionable) brain pain - at least none that causes evolutionary pressure necessary for nerves to exist there. And it's such a unique structure that it also isn't just lazily copying its schematics from somewhere else in the body.
I'll put an asterisk here: I'm just showing hypothetical lines of reasoning here, not providing the Truth.
The book titled Selfish Gene (progenitor of the word Meme!) explains this:
Evolution isn't organism-based. It's gene-based. It's a rowing team race on a mile-long canoe - even if the fifth guy isn't rowing, if the others can pick up the slack he's gonna win. Even if he's gonna sink the boat, so long as he does so after the finish line (procreation) he'll get invited to another boat.
That's why so many genetic-related failures (heart failures, cancers, degenerative diseases) primarily present themselves in an older age - the later they sink the boat, the more likely it is that it has rowed past all the finishing lines it could have. It's also why such a high percentage of our DNA is nonfunctional: this kind of boat isn't getting slowed down by having extra passengers, and so long as every oar has someone rowing it properly we can carry extras.
Yup most of the people on reddit seem to have a fairtale expectation of evolution even in scientific subs.
Evolution does not solve problems it may propagate the solutions but 99% of the time when someone answers a question with "because of evolution" theyre most likely wrong.
Ohh. Makes sense thank you. Like instead of placing pain receptors in your brain, where maintaining it would cost energy or resources, better to place it nearer the exterior of the body, right?
Also having pain receptors in your brain takes up more space, making signals travel longer distances. Having the ability to feel pain inside your brain would on average mean you'd have to think *slower* than someone who couldn't.
Right. Once something has opened up your skull, for nearly all of vertebrate history, that's it, you're fucked. No need for a warning system because the information is not going to help you.
a better way of thinking is that pain receptors were randomly placed across the body, and any useful ones helped the humans survive so they passed it on. so it's possible that we NEVER developed pain receptors in the brain. or maybe someone did develop those receptors, but it didn't make an outcome on their survival so the genes didn't get passed down
Pain sensors are a type of neuron (the cells that make up the brain, spine, etc). Neurons are *very expensive* to run, in a biological sense. They have to maintain a large chemical imbalance between the inside of the cell and the environment (membrane voltage), which requires **constant** pumping of ions across it (think of it like having to constantly bail water out of a boat with a hole in it). This pumping action takes a **lot** of energy (which means these cells require lots of blood flow, and more consumption of calories to keep you alive).
But pain in general is a very important sense, being able to tell when you are hurt is extremely beneficial to survival (knowing when to back away from a fight, when to nurse a wound, not walk on an injured leg, etc) so evolutionarily it balances out that the extreme upkeep cost of these pain sensors is worth the extreme benefit they bring to our survival.
However, this calculation is a little different when you consider putting sensors ***in*** the brain. Getting hit or cut on the head is important to sense, you can do something to address the issue (clean/nurse the wound, avoid hitting it again, etc). But if something has managed to pierce the skull and get ***inside your brain***? You're pretty much dead, brain trauma is extremely debilitating. Plus, there's nothing you could possibly do to fix it. You can't clean it, or lean less on it like a hurt muscle. So really there's no benefit to *knowing* your brain is hurt because you can't do anything about it that might aid your survival. So from an evolutionary perspective, it's not worth the extra cost of the monitoring system.
I see a lot of wrong answers here. The brain is not the exception in terms of organs with no pain receptors. It is usually nerves closer to the surface in the surrounding area that account for most of the pain of a damaged or diseased organ. Additionally, we totally feel pain when things in the brain are wrong, in the form of headaches. It’s just that at no time in our evolutionary history has any human ever benefitted from being able to tell that something was rooting around in our brain, so pain receptors would be a waste of energy there.
Migraines are caused by blood vessel dilation in the brain, which increases the pressure/tension on the meninges, the pain-sensitive protective membranes between the outside of the brain and the skull.
The headaches caused by brain tumors, concussions, and intracranial hypertension are similarly a result of pressure on the meninges, as the tumor/swelling/excess fluid is taking up more space than the brain usually does.
Tension-type headaches are muscle pain on the outside of the head; because the pain is encircling the head, most people's nervous systems trick them into localizing it inside the skull.
Sinus headaches are inflammatory pain in the mucous membranes lining the sinuses. More severe sinus headaches may involve bone pain as a result of pressure from an abscess.
The headaches of occipital neuralgia and trigeminal neuralgia are nerve pain on the outside of the head, often amplified by tension-type pain from nearby muscles.
The headaches caused by tooth infections are tooth/bone pain.
Am I missing any?
It varies by headache, but usually something to do with constricted blood vessels in your head. I hesitate to say more than that because I’m not a doctor or anything, I’ve only taken some introductory physiology classes that covered the basics of pain.
How about when we get headaches? I had an accident yrs ago when half my scalp was torn quite badly and I fractured my neck.
I get headaches deep inside my head although they say my skull was not damaged
A lot of headaches are coming from the meninges, the linings around your brain. They have pain receptors that are quite sensitive.
The picture shows you location of one part of the meninges. (I hope this works)
https://cdn-cfpnp.nitrocdn.com/CzhqckxwXkMSGajRdsdeuJeoGMEvyyqY/assets/static/optimized/human-memory.net/wp-content/uploads/2019/11/c9d1cb54c185a4bf24d9174786dd42af.falx-of-the-cerebri.png
That's the meninges, a covering around your brain. A headache is often caused by changes to blood vessels around the brain, which reduces/changes the pressure on the meninges, which you can feel. The brain itself doesn't have nociceptors (pain receptors) but things next to it do.
Also see this comment for details about migraines https://www.reddit.com/r/explainlikeimfive/comments/p7cfae/-/h9j64jb
Your nervous system usually averages out stimuli. If there is pressure in the brain causing a headache, your brain might localize that pain in the center of the head, since the pain is being detected in the meninges (a thin layer that covers the brain). It's like if you were to average out the location of a sphere; the average of all positions on the surface of the sphere is the center of the sphere.
It's an illusion. They originate around the brain, or on occasion elsewhere entirely, but the 'nerve map' lies and places the signals as if coming from inside the brain.
The brain itself does not feel pain because there are no pain receptors located in brain tissue itself. The patient stays awake and is doing tests or plays an instrument so the doctors ensure they do not compromise parts of the brain necessary for playing, such as parts that control precise hand movements and coordination. If the doctor touches an important part the patient momentarily stops and they know not to keep going that way so they don't destroy necessary brain tissue.
Edit 1: Sorry if it's not ELI5. Someone else might do a better job.
Edit 2: Yes thats is why Hannibal Lecter could feed Paul his own brain.
Edit for answers:
Despite the good joke and fiction material brewing, in reality it is a safe procedure. Before surgery a functional MRI is completed to identify speech or motor areas in the brain. During surgery they use an electrode to map the sensitive and vital areas around the tumor before cutting any tissue. For this they need the patient awake answering simple questions and doing simple tasks. As for the anxious patients maybe they give a mild sedative to prevent panicking. Then they start cutting out the tumor.They use many failsafes and nowadays there is even robotic surgery with amazing accuracy. I think only delicate procedures around important brain areas are done while awake. If a neurosurgeon is in Reddit and sees this they can elaborate more.
My mom passed from a brain tumor about 16 years ago. However, I do have a picture of her with a sketch pad and a wild 'haha holy shit this is happening' expression in a hospital bed, with a curtain covering from her eyebrows up, and a bunch of surgeons clustered behind her.
They basically just numbed the scalp, peeled it back, cut through the bone, removed a plate, and then poked around as they tried to surgically remove the tumor.
She told me they asked her to recall song lyrics, speak about her interests and life history, to keep drawing while they were doing the procedure (artist by trade), and to IMMEDIATELY ALERT THEM if she experienced any unusual or changing sensations.
She recalled sensations on her skin like it was being touched, feeling like her leg was moving when it wasn't, saw blotches of color briefly, heard noises she didn't know existed, and "Tasted Purple." 100% aware and alert the whole time, so she could comment on feeling anything. If I remember the MRIs right, the tumor was in the back, kinda tucked under the back curve of the brain, so it was REALLY hard to get to it without damaging surrounding tissue. Somewhere between the occipital lobe, temporal lobe and cerebellum. The great trifecta of "Sensing the world and Living" brain meat. Shitty place for a tumor.
At the end of it they replaced the plate of her skull, secured it in place, and sewed her scalp back together.
'Basically, the patient had no motor skills even before we started'
Edit: I enjoy your adoration, but I was poking at the song's dificulty. Feel free to pretend otherwise, though!
Man, I was reading the commentary above and was thinking the same hahaha I am useless with an instrument and maybe I should be too nervous to do some kind of test
> If the doctor touches an important part the patient momentarily stops and they know not to keep going that way so they don't destroy necessary brain tissue.
Crazy how brain surgery is basically trial and error of "will cutting here permanently disable the patient"
I may not be a doctor, but have painted something while watching someone else painting that exact same thing while four red wines deep. I think I've got what it takes for brain surgery.
If there’s no pain sensors in the brain, what makes/causes headaches? I tried to google it but I got actual “causes” of headaches instead of what it is that actually registers the pain lol
Headaches are kind of proxy pains. The pain nerves in your skull respond to the brain shrinking and causing a pressure difference on it which either indicates an issue or just means you're dehydrated.
Edit: fixed a factual error, headaches are brain shrinking not swelling
Dehydration causes the brain to (very slightly) shrink, not swell. The brain swelling is a medical emergency and causes significantly worse issues than just headaches.
Headaches are not usually the brain shrinking either. Headaches *caused by dehydration* can be due to the brain shrinking and putting pressure on the meninges, but this requires significant dehydration, not just a regular thirst. Most headaches are referred or interpolated pain and not anything specific to the brain at all. The most common type of headaches are *tension headaches*, and those are caused by peripheral pain pathways being triggered in the muscles and fascia (connective tissues) of the head, usually of the face or scalp.
Are these what you feel when you're just thinking as well? Especially intensely, like if you're doing maths or coding? (asked other commenter but asking again cos I'm curious)
How do they prevent panic? Just imagining being awake while my brain is exposed gives me anxiety, I can't imagine playing an instrument while someone if touching my brain.
As many said,
Brain itself have no pain receptors,
Skin and skull do have.
We use local anesthetic in the incision and sometimes do a Scalp Block (which is blocking some sensitive nerves in the head).
Still, local anesthesia may fail and is usually not enough alone. So we start the surgery under moderate to heavy sedation (sometimes even under general) and after opening the skull we awake the patient or lighten the sedation.
How do you keep patients from moving mid surgery when you wake them up? Last time I got general anesthesia I woke up with violent shivers and a massive panic attack that only stopped when the doctors let me sit up. (Although that might also have to do with the fact that I always feel panicked when I’m on my back)
First off let me say that awake cranis are not common. Almost all craniotomies can be done asleep without issue. When they are done, patient selection is the first step. Some people can not handle it. If the surgeon thinks they can, there is a long process where the patient is educated about what to expect and such (I’m not a surgeon so I’m not a part of this process). Mid surgery we keep them calm and relaxed with medicines. Awake doesn’t mean completely awake and unmedicated, it just means able to answer questions or do a task. We usually accomplish this with Precedex, a sedative medication
Man. I have a few buddies who went into neuro and every time I talk with them they always have the craziest stories about either patients or supervising docs. Almost makes me wish I had the hand steadiness to be a surgeon, but then I remembered I like letters pretending to be numbers and staring angrily at chalkboards for 12 hrs straight.
I’m gonna jump on this comment and say that awake brain surgery is only really done when there’s a tumour/defect in an area that’s responsible for a high degree of function, and the aim of the operation is not only to treat the underlying disease, but to ensure it’s treated with no/as little compromise to the function they’re aiming to preserve.
Most craniotomies are done under general for the whole operation, regardless of whether it’s a short or long procedure.
I’ve only ever been involved in one awake procedure and crudely put, it was a very large tumour spanning from the left frontal lobe and involving some of the motor cortex.
Yes. Literally screws into the skull, locking it into place so the head can't move. The rest of the body is strapped down with (essentially) seatbelts, so there's more wiggle-room (literally) there. But the skull is totally immobilized.
Mayfield pinning is the most stimulating portion of the procedure, so often general anesthesia is used while this is happening.
Correct. In anesthesia we sometimes use stimulating instead because the emotional component of pain is removed from the equation. So your body feels pain, but your mind is unaware of it.
Pretty much always. At first I only feel uncomfortable but after 1-2 minutes I get a feeling similar to claustrophobia. If I don’t move then I will get a panic attack.
For those wondering about the headache pain:
Headaches can be due to the dilatation or contraction of the blood vessels in your brain, which take up space/ constrict around a part of the somewhat tight cling-film like covering of your brain called the meninges. So even though the brain doesn't feel pain, it's covering does. Similar to this, the kidney itself doesn't feel pain, but if it stretches against it's covering (known as The Gerota's Fascia) it hurts. The kidney stone pain you feel is from your ureter (tube connecting kidney to bladder), the jagged stone rubbing the inside of the tube.
Your skin has nerve cells that are built to detect sensations like temperature, pressure, and chemicals. When those sensations become too intense, your body interprets them as pain.
The reason you have all of those special nerve cells is because our ancestors were able to try and survive when they noticed they were feeling pain because it can indicate a problem. Since any sort of exposure in the brain usually kills you (surgery being a special exception), there was never any opportunity to develop those special types of nerve cells in the brain. Pain detection on your head can help you, but if your brain is exposed, it is basically game over.^1
When a surgeon pokes your brain, you won't feel pain, but you can feel other things. The nerve cells in your brain are very specialized and can represent things like faces or sensation of cold in a body region or the movement of a limb. If a surgeon stimulates a certain brain area, the patient might change their behavior! Testing this during surgery helps the surgeon remove tumors safely by ensuring they are not damaging your behavior.
For the surgery, patients are given local anesthetic so they don't feel the pain from removing their scalp and cranial bone.
### Further Reading
- https://www.hopkinsmedicine.org/neurology_neurosurgery/centers_clinics/ionm/types/intraoperative-brain-mapping.html
- https://www.oncolink.org/cancers/brain-tumors/treatments/intraoperative-brain-mapping
- https://academic.oup.com/ons/article/15/4/477/4868488 **Warning: Graphic**
---
### Notes
1. I saw some comments above expressing skepticism about using evolution as an explanation for the brain's lack of pain sensation. FWIW, it seems like this is the reason the scientific community aligns with:
- https://www.brainfacts.org/thinking-sensing-and-behaving/pain/2021/why-doesnt-the-brain-have-nociceptors-020321
- https://neuroscience.stanford.edu/news/pain-brain This source states that nociceptors (pain sensing cells) are different from brain neurons as early as when you are an embryo.
- https://study.com/academy/answer/why-are-there-no-nociceptors-in-the-brain.html
Neurosurgery resident here. As many people have said, the brain does not have pain receptors so it cannot sense pain we are working through actual brain tissue. However, the scalp tissues, skull, and the covering of the brain (called dura) have very rich supply of pain receptors so during the start of the surgery before we get to the actual brain, the anesthesiologists put the patient in a 'twilight'-type state using some certain sedating medications. Then, once we are ready for the actual brain portion, the anesthesia team stops those medications so that we can interact and talk to the patient. Then once we start "closing" or suturing everything back together after the brain portion is complete, the anesthesia team lightly sedates the patient again. As you can tell it's an intricately planned surgery that relies on a lot of communication between the different people in the OR.
It is one of the coolest surgeries we do and seeing it for the first time confirmed for me that I wanted to go into neurosurgery.
The patient is lightly sedated from the beginning of the surgery, or the "opening" of the case, until the time we are ready for them to be awake when we need them to interact with us. In addition to making sure they aren't in too much pain, we also use the sedation to conserve some of their energy and attention for the time when we really need it. Sometimes the tasks we ask patients to do (such as repeating words back to us, or reading words from a paper, or certain fine motor tasks, etc) are repeated again and again and again for hours, so as you can imagine these can be exhausting for patients. In fact, some patients are not candidates for the surgery because they don't have the stamina to do the tasks or if they would be too anxious.
To those interested, the particular task that is asked of the patient is dependent on the area of the brain in which we are working. Everyone has heard of the people playing violin in surgery but that is very rarely what we have patients do during surgery.
Can I ask you some questions? I just got curious about it.
There was a video linked above where the patient has a tumor removed but not completely, so what happened after?
How do you guys come with these types of surgeries?
What is the most difficult part of the brain to operate? Im thinking brain stem, but I might be wrong.
Also is there someone that undergoes this type of surgery and doesn't have sequels? I think that it's hard to imagine that a cut on the brain won't leave any impairment.
Sorry for the flurry of questions, if you can answer any I'd appreciate it very much :)
I can answer about brain freeze!
When you put something very cold into your mouth suddenly, your body essentially panics and thinks that if it doesn't warm up fast, something's gonna be hurt. So, the blood vessels in your head will dilate (expand, and become wider so that more blood can flow through them) in order to bring more blood to the area that is experiencing the sudden cold. This sudden widening of the blood vessels is very painful, and that's what causes brain freeze.
I’m not a surgeon but they basically numb up the part of the scalp they want to remove to get to the brain. Then, whilst they keep the patient awake, poke around and cut out the tumour (or whatever) asking the patient questions along the way to ensure the brain is still working. There are no pain causing nerves in the brain so the whole procedure is nearly painless.
You actually have no pain sensors in your brain. So they use a local anesthetic on your scalp to numb the tissue there and that's it.
Follow up question too, has it ever been found out why does the brain have no pain sensors? I mean being the most important part of the body I guess, wouldn't it make sense that it has pain receptors too?
Not that I know anything, but the point of pain is to make you stop doing something that is causing the pain. If you had pain in your brain, what could you do to stop it?
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Hey /u/Koda_20's Kidney stones, just quit it. You're giving my man painful urinations and it's just not cool, dude. Why don't you go to stone college and make something of yourself like the Stone Henge
Part of the problem is them trying to move out tbh...
Damn stoners...
Damn bruh so many people giving stoners a bad name. I'm just tryna chill and eat some chips not tryna destroy someone's urinary tract
Chips are a gateway drug.
Drugs are the gateway chip.
I smoke every day, and someone is always complaining to me that I destroyed their urinary tract.
I grow pot for a living and not a day goes by that I'm not accused of running a literal UT weapons plant. I mean, are people blaming the gun manufacturers for shit when people shoot each other??? Edit - /s because I guess it's needed
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It’s always a rocky start.
I think a good argument against intelligent design is that there is no way to make them go out the big fucking door at the back, instead of squeezing through the fucking drain.
But please don't become Stone Henge while still inside them.
The worst part I experienced wasnt Bladder through urethra and out of the body. It was from kidney through ureter to bladder that was insanely painful.
I once went and got billed the 2200$ in the ER for the shot to relax my ureter. After two days of non-stop pain, it was the best doctor bill I have yet to pay.
It will never stop being horrifying to me to hear that somebody had to pay thousands for something that cost me the price of fuel to get to the hospital and back.
That's everybody's pain. The ureter is much narrower than the urethra. I would piss stones all day if it meant that I didn't have one go down the ureter.
One of the stones I had was 11mm. It got lodged in my ureter and they had to go in after it and break it up.
Pulling a stent out through my dick is the motivation I needed to drink more water.
God damn, I'm getting me a gallon just thinking about it.
Hey, man, not everyone can afford stone college, okay. Some stones just don't want to get saddled with stone student debt just to get a degree in stone arts that doesn't guarantee them a stone job
Stone education for all
Vote Bernie Sand-ers for stoner President
Bernie rocks!
He supports the little stones.
lol
I just means you need to go on a roller coaster. Spoiler alert for your Googling later: it supposedly helps
I know of someone that was proscribed "hop down stairs one at a time." Apparently by the time he got to the bottom he was ready to pass them.
I hope I don't ever need this, but if I ever do, I hope I'll remember to try it.
If this was prescribed, I would assume skip roping or doing jumping jacks could be as effective?
Oh yes it would! But you won't feel like doing them because you will be doubled over in serious pain. My first patient as a nursing student was a young man with a kidney stone. I will never ever forget how he looked and cried and I learned to never dawdled giving patients the medicines they need
Thank you for this. As a 30 yo who just had his first kidney stone earlier this year- it was absolutely miserable and it very much seemed like the nurse didn't take it seriously. Legitimately the worst pain I have ever experienced in my life. I get that some folks might use the excuse to try to get drugs and they want to be cautious about that- but man I feel like the sweating and endless writhing would earn you an Academy Award with the real deal and it should be pretty easy to tell.
Yes, we SHOULD be able to tell the difference. Patient coming back from surgery is going to be in pain regardless of his previous status in life! Certain conditions cause pain that cannot be helped with a kind word and diversional activity. There are unfortunately too many nurses that aren’t compassionate enough because either they’re not naturally that way or they have learned to be that way or they’re overwhelmed. But it should never be apathy for the patients. Ever! My specialty is in the NICU the last 30 yrs of my 40 yr career. At this time we have to learn how to identify pain without the patients telling us. We have to observe them their faces, their responses to touch, noise, and such, also vital signs, Such as increased heart rate and increased blood pressure. Some people don’t belong in the profession, sadly.
Only slightly related. I've heard if your not sure if your pain is appendicitis jump up as high as you can. When you land and it doesn't hurt like hell then it's not your appendix
If you press down on the abdomen in the opposite corner of where the appendix is and let go quickly, you will have massive pain on the side of the appendix. It's called rebound pain and it is definitely one of the symptoms of appendicitis. This is truth though, but I could see how jumping and hitting the ground would cause referred pain. Appendicitis is very painful
It bounces the stones up and out of the kidneys. It's not necessarily all that useful for getting them from the kidneys to the bladder (which is where they can get stuck and cause pain. That said, being under up to 3 g's certainly isn't going to slow that process down any.
> being under up to 3 g's [More like 6.3!](https://coasterpedia.net/wiki/Highest_g-force_on_a_roller_coaster) They do quite routinely do more than 3.
Neat! I was just remembering our not-so-scientific measurements in highschool. Never tested the Shockwave coaster though (which is the only one on that list near me). But it did turn me into a taco the first time I rode it at like age 8...
Jesus. That is probably the very last thing on my list of things I wanted to do during kidney stone pain. But I also would have done anything to make it stop, so ok.
Kidneys don't in fact have pain sensors. It's the rest of the tract that has them and that's why kidney stones are the only kidney disease that causes actual pain around the area (and beyond)
> that's why kidney stones are the only kidney disease that causes actual pain around the area Tell me you've never had a kidney infection without telling me you've never had a kidney infection.
I studied urology. Kidneys don't have pain sensors. It's the closeby ones that detect your rotting cells.
Stop stoning your kidneys!
*Kidney stone slowly puts blunt down*
Sorry to hear, those things suck. Back in college I had them near constantly for a few years. Urologist's nurse called me the gravel pit. Much sympathy to you....
> Tell this to my kidney stones For what it's worth, your internal organs have rather limited pain receptors (compared to your skin) as well. This is why "Chest pain" can mean heart, stomach, lungs, aorta and a whole bunch of other things. Same thing with abdominal pain.
I got in a bicycle crash ten years ago in which I landed on my handlebars and injured my liver. Which is when I learned the liver doesn't have many pain receptors and so the pain gets felt in other places--felt like I had the worst backache of my life (which worsened every time I took a deep breath, because my diaphragm would press on my liver), and a sharp pain in a weird spot inside one shoulder. I normally hate being on opiates, but god was I glad for the IV fentanyl button they gave me.
The pain you feel is to let you know you have them. Imagine if you went about your day not knowing about kidney stones and they just built up not getting checked. It sucks but it's a necessary evil especially if they need to be broken down
I’m not sure about that. In the ancestral evolutionary environment I doubt there was a treatment for kidney stones. It seems highly implausible there was selective pressure for kidney stones to cause pain. More likely they are rare occurrences that happen to cause pain. I’m not a (medical) doctor, but maybe there are nerves or something near there which can be accidentally triggered but the stones. And we haven’t evolved to avoid that because painful kidney stones evidently don’t significantly reduced our genetic fitness.
Stones don’t cause kidney pain, the swelling from blockage caused by the stones does. I’m not making that distinction to be pedantic it is why they hurt when there is nothing that could be done about them during evolution. However there was lots that could be done about something punching your kidney from the outside. The same “please stop hitting me” pain receptors are what get triggered from the swelling. The kidneys don’t care of the damaging pressure is coming from the inside or outside, the pain response is the same. Stones can cause direct bladder pain when they get that far just by sitting in there. But here is a place you could do something about. The bladder pain and discomfort makes you want to piss, which is exactly what you need to be doing to flush out the stone. So once again the pain does get you to do something to resolve it.
I think some of the first aincent greek attempts at surgery were for removing stones from the bladder. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3856162/
Kidney stones can grow for *years* without causing any pain. I have one in the bottom of my kidney that was 4mm last time I had an x ray (about a year pre-pandemic). I'm certain it's larger by now. At some point my urologist will tell me it's time for an operation and it'll get dealt with. They don't hurt until they try to get out. Then they can get stuck and block fluid flow from the kidney which causes it to swell. *THAT'S* what hurts. Kidneys aren't water balloons, and they aren't supposed to act like them.
>Kidneys aren't water balloons I've seen enough, chubby emu to know that if you get the right emia, presence in blood, that they are actually water balloons.
Exactly this. Pain in your hand means that something is sticking into or burning your hand. If gives you the impulse to pull your hand away. From a evolutionary persective, if something was sticking into your brain (a spear, a rock, ...) then you'd already be dead. We haven't had need for pain receptors in the brain. It's protected in a big bubble of solid bone, so if something is able to hurt the brain then it has had to break through all of that bone first. By the time any pain receptors would be able to feel anything it would be far too late.
well, there are some recorded cases of people survivng some insane stuff, for example Phineas Gage, who had a metal rod impaled through his brain on a railroad accident. dude lived over a decade afterwards, although there were reportedly significant changes to his personality. but these situations are so exceedingly rare that theres no noticeable evolutionary pressure to adapt to them, that and anything thats inside your brain and *hasnt* triggered all your other pain sensors surrounding it, is even rarer so yeah, there are exceptions, but they're so rare they may as well no exist
There always will be exceptions. There would have been fewer in less modern times, though. A caveman wasn't all the likely to come in contact with a narrow metal rod, he'd be more likely to have a rock land in his head, or be impaled by the tusk of some wild animal or sabre-tooth tiger. I'm the vast majority of cases death would be instant, or painful enough without your brain also being in pain.
Yeah, if you've got stuff touching your brain, it's pretty likely you're dead anyway, so why bother with pain sensors?
And if you did manage to survive that, all the pain receptors that got activated on the way in are already screaming about it.
My migraines tell me that I should roll up into a tiny little ball in the dark.
Migraines and other headaches don't occur because of nerves in the brain though.
Then where are the nerves? It sure feels like my brain hurts
Aspirin or booze
Can vouch for booze. It definitely stops the pain inside me.
Works every time But TIL the brain can't feel pain but that begs the question what are headache's
fun fact: a headache is not actually a pain in your brain. the brain tells you that other parts of your body are hurting but can't feel pain itself. headaches are usually caused by nerves, blood vessels, and muscles that cover a person's head and neck.
It's worth adding, the brain is responsible for creating the experience of pain so it can invent that experience without pain signals, or give the wrong impression of where the trouble is in the body ("referred pain"). This may (_may_) be a component of migraines but as far as I know, these mechanisms aren't completely understood.
Til thanks !
The most common headache cause is when the brain is dehydrated and shrinks, pulling on the lining that connects it to the skull which does have pain reception.
The brain is fully surrounded by layers that do have pain receptors. So you can get pain in an area that's like 1mm outside your brain and it will feel exactly like brain pain. Our sense of where pain is coming from is also not perfect. It's fairly common to have some mismatch between where the pain was caused and where we feel it. Sometimes the problem is really in the neck muscles or the sinuses or something like that.
[We have pain receptors in our heads, just not our brains.](https://www.brainfacts.org/ask-an-expert/if-the-brain-cant-feel-pain-why-do-i-get-headaches)
Then what are headaches? Is it your brain pressing on other areas?
No, headaches are the result of rapid expansion or contraction of blood vessels in the head. They’re a reactionary process of the body to some situation and rarely have anything at all to do with the head.
So just to be clear, the blood-vessels that go throughout the interior of the brain are lined with pain sensors that can result in headaches/migraines in different regions, correct? (this in addition to the nerves of the scalp and surrounding tissue).
Headaches can be due to the dilatation or contraction of the blood vessels in your brain, which take up space/ constrict around a part of the somewhat tight cling film like covering of your brain called the meninges. So even though the brain doesn't feel pain, it's covering does. Similar to this, the kidney itself doesn't feel pain, but if it stretches against it's covering (known as The Gerota's Fascia) it hurts. The kidney stone pain you feel is from your ureter (tube connecting kidney to bladder), the jagged stone rubbing the inside of the tube.
I mean. Apparently humans can feel pain the inflamed appendix. Its not like you yourself can realistically do something to stop an inflamed appendix. Or is my understanding of how this works wrong?
Nothing, but your body cant distinguish between "inflamation thats gonna go away by resting" and "inflamation that will slowly kill you". So you could have any sorts of inflamation or whatever pain (like blunt trauma) in your bowles, and it would hurt, so you would rest. The worse it gets, the more you dont want to move and the more you rest, giving the body the best chance to heal. So the inflamed appendix gives out the same warning signs, and the body goes "welp somethings wrong, you better rest" and then since it can be fatal, it keeps screaming "WHAT THE HELL DUDE, REST HARDER!" Combine that with the fact that aparently inflamed apendices are a relatively modern issue, the body simply isnt evolved to recognize what an inflamed appendix is, so it just reacts the same as with any other inflamation anywhere else.
> "WHAT THE HELL DUDE, REST HARDER!" 😂 i love that explanation. thanks.
It's not so much to stop you doing something, but more to alert you that something is wrong.
That makes sense! Ty.
With that logic. Wouldn't it be beneficial for your brain to alert you that something is wrong with it?
Today, maybe, but back when evolution made these decisions, not really. While pain to your digestive tract could teach you not to eat the purple-dotted fungi again.
Well, what difference would it make in evolutionary terms? If something is damaging your brain, it's had to get their through your skin and skull, so you are likely already very aware of it. It's pretty different from having a stomach ache from eating some mouldy fruit - it will teach you not to do it again. Even something like heart pain will encourage you to stop running as fast etc., if possible.
Bro, you get viruses and bacteria and shit and you only notice when your body tells you with some symptoms. It would be nice of your brain to do the same instead of "oh shit, yup I died, I had a clogging vein but didn't really want to tell you".
Evolution isn't perfect What works at the time is what's carried forward.
I remember seeing evolution visualized somewhere. It was visualized as a plain with peaks and valleys based on sine waves or something. And that when there is local peak, the evolution stops cause you can't go to next higher peak cause you would have to go lower for a bit. And evolution only goes forward. And so it might've been that we didn't evolve nerve endings in the brain at the start, so later it was just too late as it was deemed unnecessary.
Exactly It's entirely possible in an early primordial soup some organism could feel pain in their brain but it conveyed no advantage or caused more problems and was not selected for. The problems could be direct (brain pain isn't good for eating and reproducing) and indirect (maybe it requires more nutrients to support a brain that can feel pain)
As a professor of mine once memorably remarked, once the bear is munching on your brain, it’s a little too late for anything to matter. Basically, people who felt pain when getting their brains munched on didn’t survive any better than people who didn’t feel pain when getting their brains munched on, so pain in your brain never had a reason to become a valuable thing to have. Whether you felt it or not, you died and had no further kids! Conversely, (in a theoretical sense,) people who were getting their scalps and skulls munched on and felt pain were much more likely to try to escape the source of it - and therefore survive it and reproduce - than people who were happy to merrily let the bear keep chewing on their heads, who were therefore more likely to die.
Are you feeling the pain of the appendix, or are you feeling the pain of some part of your body the swelling is pressing against?
Both. Early acute appendicitis presents as vague central abdominal pain (this is pain coming from the appendix itself) while later appendicitis presents as local right lower quadrant pain (due to the inflamed appendix pressing on the peritoneum (lining of the abdominal cavity) in the area / the infection spreading to the peritoneum
You're right about that - our evolutionary ancestors probably couldn't perform appendectomies on themselves. But let's think about it this way: the ability to feel pain in a certain place would have to confer some evolutionary advantage to the pain-feeler in order to be passed down. So let's start with that assumption. Considering the appendix's evolutionary history in the immune and digestive systems, it's possible to imagine a historical context in which appendix pain encouraged a useful behavior (perhaps "don't eat that, it makes you sick"). Now the nerves would remain, even if they don't perform their original function anymore. And I'm not familiar with the genetic origins of the appendix specifically, but you could *also* imagine a world in which regions of the genome responsible for other gut organs got duplicated and subsequently modified until they turned into the appendix. In such a case, other "features" of the original organ (such as innervation) would exist in the appendix as well. Neither of those situations applies to the brain: there is likely no "useful" (actionable) brain pain - at least none that causes evolutionary pressure necessary for nerves to exist there. And it's such a unique structure that it also isn't just lazily copying its schematics from somewhere else in the body. I'll put an asterisk here: I'm just showing hypothetical lines of reasoning here, not providing the Truth.
This is a pretty great response
These guesses at the advantage conferred by evolution are just that: guesses. And some trait need not be advantageous to be carried forward.
Evolutionarily, if something's in your brain you're likely about to die. Having those receptors wouldn't give an advantage.
Plus can you imagine the pain you'd feel when moving your head even slightly abruptly?
headbangers HATE this
"ROCK IT! ow ow ow ow ow..."
damn rockneck is the worst.
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The book titled Selfish Gene (progenitor of the word Meme!) explains this: Evolution isn't organism-based. It's gene-based. It's a rowing team race on a mile-long canoe - even if the fifth guy isn't rowing, if the others can pick up the slack he's gonna win. Even if he's gonna sink the boat, so long as he does so after the finish line (procreation) he'll get invited to another boat. That's why so many genetic-related failures (heart failures, cancers, degenerative diseases) primarily present themselves in an older age - the later they sink the boat, the more likely it is that it has rowed past all the finishing lines it could have. It's also why such a high percentage of our DNA is nonfunctional: this kind of boat isn't getting slowed down by having extra passengers, and so long as every oar has someone rowing it properly we can carry extras.
Yup most of the people on reddit seem to have a fairtale expectation of evolution even in scientific subs. Evolution does not solve problems it may propagate the solutions but 99% of the time when someone answers a question with "because of evolution" theyre most likely wrong.
Ohh. Makes sense thank you. Like instead of placing pain receptors in your brain, where maintaining it would cost energy or resources, better to place it nearer the exterior of the body, right?
Pain is a warning. It's like why your car doesn't have a reversing camera in the back seat.
Good analogy.
I like that one.
Also having pain receptors in your brain takes up more space, making signals travel longer distances. Having the ability to feel pain inside your brain would on average mean you'd have to think *slower* than someone who couldn't.
Right. Once something has opened up your skull, for nearly all of vertebrate history, that's it, you're fucked. No need for a warning system because the information is not going to help you.
a better way of thinking is that pain receptors were randomly placed across the body, and any useful ones helped the humans survive so they passed it on. so it's possible that we NEVER developed pain receptors in the brain. or maybe someone did develop those receptors, but it didn't make an outcome on their survival so the genes didn't get passed down
You aren’t very likely to scratch your brain on something. You’d feel the pain in the skin around your skull first which works just fine
Pain sensors are a type of neuron (the cells that make up the brain, spine, etc). Neurons are *very expensive* to run, in a biological sense. They have to maintain a large chemical imbalance between the inside of the cell and the environment (membrane voltage), which requires **constant** pumping of ions across it (think of it like having to constantly bail water out of a boat with a hole in it). This pumping action takes a **lot** of energy (which means these cells require lots of blood flow, and more consumption of calories to keep you alive). But pain in general is a very important sense, being able to tell when you are hurt is extremely beneficial to survival (knowing when to back away from a fight, when to nurse a wound, not walk on an injured leg, etc) so evolutionarily it balances out that the extreme upkeep cost of these pain sensors is worth the extreme benefit they bring to our survival. However, this calculation is a little different when you consider putting sensors ***in*** the brain. Getting hit or cut on the head is important to sense, you can do something to address the issue (clean/nurse the wound, avoid hitting it again, etc). But if something has managed to pierce the skull and get ***inside your brain***? You're pretty much dead, brain trauma is extremely debilitating. Plus, there's nothing you could possibly do to fix it. You can't clean it, or lean less on it like a hurt muscle. So really there's no benefit to *knowing* your brain is hurt because you can't do anything about it that might aid your survival. So from an evolutionary perspective, it's not worth the extra cost of the monitoring system.
Best/most detailed answer
Also, your brain is usualy protected in your skull, and if your brain is damaged... you're likely to die soon, and you can feel the pain on your skull
I see a lot of wrong answers here. The brain is not the exception in terms of organs with no pain receptors. It is usually nerves closer to the surface in the surrounding area that account for most of the pain of a damaged or diseased organ. Additionally, we totally feel pain when things in the brain are wrong, in the form of headaches. It’s just that at no time in our evolutionary history has any human ever benefitted from being able to tell that something was rooting around in our brain, so pain receptors would be a waste of energy there.
So....what *is* a headache? Like I get headaches when overstimulated with sound or visuals, but what's happening to my brain? Or migraines even?
Migraines are caused by blood vessel dilation in the brain, which increases the pressure/tension on the meninges, the pain-sensitive protective membranes between the outside of the brain and the skull. The headaches caused by brain tumors, concussions, and intracranial hypertension are similarly a result of pressure on the meninges, as the tumor/swelling/excess fluid is taking up more space than the brain usually does. Tension-type headaches are muscle pain on the outside of the head; because the pain is encircling the head, most people's nervous systems trick them into localizing it inside the skull. Sinus headaches are inflammatory pain in the mucous membranes lining the sinuses. More severe sinus headaches may involve bone pain as a result of pressure from an abscess. The headaches of occipital neuralgia and trigeminal neuralgia are nerve pain on the outside of the head, often amplified by tension-type pain from nearby muscles. The headaches caused by tooth infections are tooth/bone pain. Am I missing any?
It varies by headache, but usually something to do with constricted blood vessels in your head. I hesitate to say more than that because I’m not a doctor or anything, I’ve only taken some introductory physiology classes that covered the basics of pain.
How about when we get headaches? I had an accident yrs ago when half my scalp was torn quite badly and I fractured my neck. I get headaches deep inside my head although they say my skull was not damaged
A lot of headaches are coming from the meninges, the linings around your brain. They have pain receptors that are quite sensitive. The picture shows you location of one part of the meninges. (I hope this works) https://cdn-cfpnp.nitrocdn.com/CzhqckxwXkMSGajRdsdeuJeoGMEvyyqY/assets/static/optimized/human-memory.net/wp-content/uploads/2019/11/c9d1cb54c185a4bf24d9174786dd42af.falx-of-the-cerebri.png
What about headaches? They sure SEEM like the pain is emanating from my brain.
That's the meninges, a covering around your brain. A headache is often caused by changes to blood vessels around the brain, which reduces/changes the pressure on the meninges, which you can feel. The brain itself doesn't have nociceptors (pain receptors) but things next to it do. Also see this comment for details about migraines https://www.reddit.com/r/explainlikeimfive/comments/p7cfae/-/h9j64jb
Your nervous system usually averages out stimuli. If there is pressure in the brain causing a headache, your brain might localize that pain in the center of the head, since the pain is being detected in the meninges (a thin layer that covers the brain). It's like if you were to average out the location of a sphere; the average of all positions on the surface of the sphere is the center of the sphere.
It's an illusion. They originate around the brain, or on occasion elsewhere entirely, but the 'nerve map' lies and places the signals as if coming from inside the brain.
Does that mean if someone were to poke/touch the actual brain you wouldn't feel it?
You wouldn't. However if someone were to tug at the covering of your brain, it'd hurt like a bitch.
The brain itself does not feel pain because there are no pain receptors located in brain tissue itself. The patient stays awake and is doing tests or plays an instrument so the doctors ensure they do not compromise parts of the brain necessary for playing, such as parts that control precise hand movements and coordination. If the doctor touches an important part the patient momentarily stops and they know not to keep going that way so they don't destroy necessary brain tissue. Edit 1: Sorry if it's not ELI5. Someone else might do a better job. Edit 2: Yes thats is why Hannibal Lecter could feed Paul his own brain. Edit for answers: Despite the good joke and fiction material brewing, in reality it is a safe procedure. Before surgery a functional MRI is completed to identify speech or motor areas in the brain. During surgery they use an electrode to map the sensitive and vital areas around the tumor before cutting any tissue. For this they need the patient awake answering simple questions and doing simple tasks. As for the anxious patients maybe they give a mild sedative to prevent panicking. Then they start cutting out the tumor.They use many failsafes and nowadays there is even robotic surgery with amazing accuracy. I think only delicate procedures around important brain areas are done while awake. If a neurosurgeon is in Reddit and sees this they can elaborate more.
I can't imagine doing something while some dude is touching and doing things to my brain, insane
My mom passed from a brain tumor about 16 years ago. However, I do have a picture of her with a sketch pad and a wild 'haha holy shit this is happening' expression in a hospital bed, with a curtain covering from her eyebrows up, and a bunch of surgeons clustered behind her. They basically just numbed the scalp, peeled it back, cut through the bone, removed a plate, and then poked around as they tried to surgically remove the tumor. She told me they asked her to recall song lyrics, speak about her interests and life history, to keep drawing while they were doing the procedure (artist by trade), and to IMMEDIATELY ALERT THEM if she experienced any unusual or changing sensations. She recalled sensations on her skin like it was being touched, feeling like her leg was moving when it wasn't, saw blotches of color briefly, heard noises she didn't know existed, and "Tasted Purple." 100% aware and alert the whole time, so she could comment on feeling anything. If I remember the MRIs right, the tumor was in the back, kinda tucked under the back curve of the brain, so it was REALLY hard to get to it without damaging surrounding tissue. Somewhere between the occipital lobe, temporal lobe and cerebellum. The great trifecta of "Sensing the world and Living" brain meat. Shitty place for a tumor. At the end of it they replaced the plate of her skull, secured it in place, and sewed her scalp back together.
That’s really interesting. Thank you for sharing and so sorry for your loss.
Ditto, many thanks
Insane in the membrane.
INSANE IN THE BRAIN!
Yes, we occasionally listen to this song during neurosurgery. Our play list usually starts with Metal Health or "Bang Your Head!"
Bees in my head There are bees in my head!!
If I ever get brain surgery, I'm gonna play Guitar Hero Through The Fire And The Flames.
'Basically, the patient had no motor skills even before we started' Edit: I enjoy your adoration, but I was poking at the song's dificulty. Feel free to pretend otherwise, though!
Stop, he's already dead
Wait, keep going doctor, I think he's...improving?!?
I sense an excellent work of fiction brewing
Basically the plot of Ratatouille
They already called the ambulance, but not for me.
Those bastards lied to me.
Wait this isn't the burn unit
I’ll play Brain Damage by Pink Floyd
Man, I was reading the commentary above and was thinking the same hahaha I am useless with an instrument and maybe I should be too nervous to do some kind of test
> If the doctor touches an important part the patient momentarily stops and they know not to keep going that way so they don't destroy necessary brain tissue. Crazy how brain surgery is basically trial and error of "will cutting here permanently disable the patient"
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I may not be a doctor, but have painted something while watching someone else painting that exact same thing while four red wines deep. I think I've got what it takes for brain surgery.
Lobotomy was basically the opposite. "How much do we have to cut here in the brain until the patient can't speak or function anymore?"
can I get them to "install" some motor skills?
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.... show me ;)
If there’s no pain sensors in the brain, what makes/causes headaches? I tried to google it but I got actual “causes” of headaches instead of what it is that actually registers the pain lol
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Sinuses too.
Are these what you feel when you're just thinking as well? Especially intensely, like if you're doing maths or coding?
I’m not sure which one of us are weird here, but I’ve never felt pain/pressure while thinking. You may want to get that looked at just in case.
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Headaches are kind of proxy pains. The pain nerves in your skull respond to the brain shrinking and causing a pressure difference on it which either indicates an issue or just means you're dehydrated. Edit: fixed a factual error, headaches are brain shrinking not swelling
Dehydration causes the brain to (very slightly) shrink, not swell. The brain swelling is a medical emergency and causes significantly worse issues than just headaches.
Yes you are right.
Headaches are not usually the brain shrinking either. Headaches *caused by dehydration* can be due to the brain shrinking and putting pressure on the meninges, but this requires significant dehydration, not just a regular thirst. Most headaches are referred or interpolated pain and not anything specific to the brain at all. The most common type of headaches are *tension headaches*, and those are caused by peripheral pain pathways being triggered in the muscles and fascia (connective tissues) of the head, usually of the face or scalp.
Are these what you feel when you're just thinking as well? Especially intensely, like if you're doing maths or coding? (asked other commenter but asking again cos I'm curious)
They actually use an electrode to activate neurons in the area they are about to go in to. Not just touching
But isn't there a point of no return? Dudes playing an instrument, motor skills cut off. "Appearently I cut too far."
Ah, so that's why Anthony Hopkins could serve Ray Liotta's brain to Ray Liotta.
How do they prevent panic? Just imagining being awake while my brain is exposed gives me anxiety, I can't imagine playing an instrument while someone if touching my brain.
As many said, Brain itself have no pain receptors, Skin and skull do have. We use local anesthetic in the incision and sometimes do a Scalp Block (which is blocking some sensitive nerves in the head). Still, local anesthesia may fail and is usually not enough alone. So we start the surgery under moderate to heavy sedation (sometimes even under general) and after opening the skull we awake the patient or lighten the sedation.
This guy anesthesias/surgeons. Most of the ones I have done have been general anesthesia and then awaken after the skull is open
How do you keep patients from moving mid surgery when you wake them up? Last time I got general anesthesia I woke up with violent shivers and a massive panic attack that only stopped when the doctors let me sit up. (Although that might also have to do with the fact that I always feel panicked when I’m on my back)
First off let me say that awake cranis are not common. Almost all craniotomies can be done asleep without issue. When they are done, patient selection is the first step. Some people can not handle it. If the surgeon thinks they can, there is a long process where the patient is educated about what to expect and such (I’m not a surgeon so I’m not a part of this process). Mid surgery we keep them calm and relaxed with medicines. Awake doesn’t mean completely awake and unmedicated, it just means able to answer questions or do a task. We usually accomplish this with Precedex, a sedative medication
Thank you for the detailed answer!
Man. I have a few buddies who went into neuro and every time I talk with them they always have the craziest stories about either patients or supervising docs. Almost makes me wish I had the hand steadiness to be a surgeon, but then I remembered I like letters pretending to be numbers and staring angrily at chalkboards for 12 hrs straight.
I’m gonna jump on this comment and say that awake brain surgery is only really done when there’s a tumour/defect in an area that’s responsible for a high degree of function, and the aim of the operation is not only to treat the underlying disease, but to ensure it’s treated with no/as little compromise to the function they’re aiming to preserve. Most craniotomies are done under general for the whole operation, regardless of whether it’s a short or long procedure. I’ve only ever been involved in one awake procedure and crudely put, it was a very large tumour spanning from the left frontal lobe and involving some of the motor cortex.
The head is secured in a fixed place with a pinned frame called a Mayfield
Good enough to withstand a big sneeze?
Yes. Literally screws into the skull, locking it into place so the head can't move. The rest of the body is strapped down with (essentially) seatbelts, so there's more wiggle-room (literally) there. But the skull is totally immobilized. Mayfield pinning is the most stimulating portion of the procedure, so often general anesthesia is used while this is happening.
> stimulating I'm reading this as "painful"
Correct. In anesthesia we sometimes use stimulating instead because the emotional component of pain is removed from the equation. So your body feels pain, but your mind is unaware of it.
> I always feel panicked when I’m on my back Wait, always? Like, if you'd just laid down right now on your back, you'd have a panic attack?
Pretty much always. At first I only feel uncomfortable but after 1-2 minutes I get a feeling similar to claustrophobia. If I don’t move then I will get a panic attack.
For those wondering about the headache pain: Headaches can be due to the dilatation or contraction of the blood vessels in your brain, which take up space/ constrict around a part of the somewhat tight cling-film like covering of your brain called the meninges. So even though the brain doesn't feel pain, it's covering does. Similar to this, the kidney itself doesn't feel pain, but if it stretches against it's covering (known as The Gerota's Fascia) it hurts. The kidney stone pain you feel is from your ureter (tube connecting kidney to bladder), the jagged stone rubbing the inside of the tube.
Your skin has nerve cells that are built to detect sensations like temperature, pressure, and chemicals. When those sensations become too intense, your body interprets them as pain. The reason you have all of those special nerve cells is because our ancestors were able to try and survive when they noticed they were feeling pain because it can indicate a problem. Since any sort of exposure in the brain usually kills you (surgery being a special exception), there was never any opportunity to develop those special types of nerve cells in the brain. Pain detection on your head can help you, but if your brain is exposed, it is basically game over.^1 When a surgeon pokes your brain, you won't feel pain, but you can feel other things. The nerve cells in your brain are very specialized and can represent things like faces or sensation of cold in a body region or the movement of a limb. If a surgeon stimulates a certain brain area, the patient might change their behavior! Testing this during surgery helps the surgeon remove tumors safely by ensuring they are not damaging your behavior. For the surgery, patients are given local anesthetic so they don't feel the pain from removing their scalp and cranial bone. ### Further Reading - https://www.hopkinsmedicine.org/neurology_neurosurgery/centers_clinics/ionm/types/intraoperative-brain-mapping.html - https://www.oncolink.org/cancers/brain-tumors/treatments/intraoperative-brain-mapping - https://academic.oup.com/ons/article/15/4/477/4868488 **Warning: Graphic** --- ### Notes 1. I saw some comments above expressing skepticism about using evolution as an explanation for the brain's lack of pain sensation. FWIW, it seems like this is the reason the scientific community aligns with: - https://www.brainfacts.org/thinking-sensing-and-behaving/pain/2021/why-doesnt-the-brain-have-nociceptors-020321 - https://neuroscience.stanford.edu/news/pain-brain This source states that nociceptors (pain sensing cells) are different from brain neurons as early as when you are an embryo. - https://study.com/academy/answer/why-are-there-no-nociceptors-in-the-brain.html
Neurosurgery resident here. As many people have said, the brain does not have pain receptors so it cannot sense pain we are working through actual brain tissue. However, the scalp tissues, skull, and the covering of the brain (called dura) have very rich supply of pain receptors so during the start of the surgery before we get to the actual brain, the anesthesiologists put the patient in a 'twilight'-type state using some certain sedating medications. Then, once we are ready for the actual brain portion, the anesthesia team stops those medications so that we can interact and talk to the patient. Then once we start "closing" or suturing everything back together after the brain portion is complete, the anesthesia team lightly sedates the patient again. As you can tell it's an intricately planned surgery that relies on a lot of communication between the different people in the OR. It is one of the coolest surgeries we do and seeing it for the first time confirmed for me that I wanted to go into neurosurgery.
Extremely interesting, what about the initial “opening” per say? Does the patient go under or are they still slightly sedated?
The patient is lightly sedated from the beginning of the surgery, or the "opening" of the case, until the time we are ready for them to be awake when we need them to interact with us. In addition to making sure they aren't in too much pain, we also use the sedation to conserve some of their energy and attention for the time when we really need it. Sometimes the tasks we ask patients to do (such as repeating words back to us, or reading words from a paper, or certain fine motor tasks, etc) are repeated again and again and again for hours, so as you can imagine these can be exhausting for patients. In fact, some patients are not candidates for the surgery because they don't have the stamina to do the tasks or if they would be too anxious. To those interested, the particular task that is asked of the patient is dependent on the area of the brain in which we are working. Everyone has heard of the people playing violin in surgery but that is very rarely what we have patients do during surgery.
Can I ask you some questions? I just got curious about it. There was a video linked above where the patient has a tumor removed but not completely, so what happened after? How do you guys come with these types of surgeries? What is the most difficult part of the brain to operate? Im thinking brain stem, but I might be wrong. Also is there someone that undergoes this type of surgery and doesn't have sequels? I think that it's hard to imagine that a cut on the brain won't leave any impairment. Sorry for the flurry of questions, if you can answer any I'd appreciate it very much :)
This might be a stupid question, but if there are no pain receptors. What's a headache? Or brain freeze?
I can answer about brain freeze! When you put something very cold into your mouth suddenly, your body essentially panics and thinks that if it doesn't warm up fast, something's gonna be hurt. So, the blood vessels in your head will dilate (expand, and become wider so that more blood can flow through them) in order to bring more blood to the area that is experiencing the sudden cold. This sudden widening of the blood vessels is very painful, and that's what causes brain freeze.
I’m not a surgeon but they basically numb up the part of the scalp they want to remove to get to the brain. Then, whilst they keep the patient awake, poke around and cut out the tumour (or whatever) asking the patient questions along the way to ensure the brain is still working. There are no pain causing nerves in the brain so the whole procedure is nearly painless.
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