The mysterious flow of fluid in the brain | Hacker News Reader

The mysterious flow of fluid in the brain

quantamagazine.org

149 pointspseudolus36 comments

Several years, ago I started getting cough headaches. The symptoms were just like it sounds: when I coughed, I got a headache, usually lasting for a few minutes. In addition, bending down caused a sharp pain in my head. Lying down was fine, indeed, all symptoms lessened or disappeared after a good night's sleep and got progressively worse as the day went on.

My neurologist diagnosed it as a cough headache, but he cautioned that nobody knows the root cause.

He did say that it had to be physical/mechanical, in the sense that it had to be some fluid (or lack of fluid) that caused a problem depending on your orientation (bending down) or when shocked (coughing).

He suspected it had to do with spinal fluid and he ordered tests, but they all came back normal. He said that in most patients the symptoms go away after several years, and that's what happened with me.

But reading this article, I wonder if there is some connection here. The headaches started when my second child was born and I wasn't getting much sleep. Maybe, as the article theorizes, lack of sleep caused the fluid in my brain to not drain properly or not be cleaned or something. That could be why sleep decreased the symptoms. Maybe they should study cough headache sufferers and compare against normal people.

My late wife had a brain tumor that put pressure on the sinus veins, causing increased cranial pressure that affected her eyesight.

We learned through the process that many people have significant occlusions in those veins - some 100% on one side. It’s no problem for most people… and until recently there was little to do if there was a problem.

If you ever have a reason to get a contrast MRI of your brain, do it!

How uncanny to find this thread right now, just a day after I had a bizarre case of sinus pain influencing my eyesight and dexterity somehow. Definitely something I should look into ASAP.

Thank you Baader–Meinhof I suppose.

My terminology was poor. The venous sinuses aren’t associated with your sinus. They are sort of like the storm drain for your brain, in a sense, not the same as the nasal sinus.

Sorry I can’t edit. Here’s some more info:

https://teachmeanatomy.info/neuroanatomy/vessels/dural-venou...

I want to point out that bruxism at night can also cause similar symptoms via the same pathways.

I had to pay $3K cash to get an MRI of my knee one time, wonder how much for the brain, maybe the same?

You can get it done anywhere around the world in a private setting likely for 10% of the cost.

https://ujbudamedicalcenter.hu/en/prices/

And if you go in the summer you can enjoy the warm night breeze of Budapest too!

An MRI of my lower back would have cost €160 in Europe had I been paying cash.

Imagine having a free European vacation included with your MRI...

I suppose any Soviet block country should do it for around $50.

The cough headache appearing right after pregnancy is suspicious. Did you get an epidural? I think they are finding that CSF leaks (which can be a complication of lumbar punctures and epidurals) are underdiagnosed. I wonder whether a small leak might manifest as a headache triggered by coughing and bending over.

I’ve come across cough headaches with Chiari malformations.

https://en.m.wikipedia.org/wiki/Chiari_malformation

I also have those (along with sneezing). I cannot do anything for the next 5-10 minutes until it goes away. For me it's simply (but maybe not only, who knows when reading the sibling comments) allergies. I don't have allergy symptoms like cough or watery eyes, etc. But somehow my sinuses get "full" and pressure builds up inside. If I take antihistaminic almost daily then my sinuses (mostly one side) don't fill up and I can't cough or sneeze without fear. Since you went to a doctor they probably ruled that out, but maybe not, and it checks out with their "it's probably mechanical" hunch.

Since I was a child I have been very susceptible to exertion headaches and indeed coughing/sneezing can easily trigger this. They last from a couple of hours to the entire day, being gone when I wake up. The pain is not as bad if I lie down. I'm personally convinced it is directly linked to the pressure of my cerebrospinal fluid.

MRI has of course revealed nothing. Syringomyelia was not supposed to be hereditary (father) and nothing has been detected, but there is a chance that the cavity is so small/narrow that it blocks shut when I lie down: pain subsides, nothing is there to be seen when I'm in the machine. Vertical MRI, anyone?

The "valsalva maneuver" has a 100% success rate of triggering symptoms, and recently (some years) I have begun to observe a high-pitched sucking sound, consistent duration of about a second, originating from somewhere between my right ear lobe and spine. The sound is not uncomfortably loud but could be missed if I was listening to music or having a conversation. I think I have only ever observed the sound when in a sitting position. When detected, the sound might be accompanied with a physical sensation, but it is so minimal that I'm unsure if I'm imagining it.

It's just one of those things at this point.

I occasionally get headache that I think are related to pressure in the skull cavity. I also get light persistent headaches from exertion. In my case it's easy enough to avoid but I would like to limit such symptoms.

The important thing to me for such articles is that they demonstrate how ignorant we are about the functioning of the brain.

In living things, all the processes seem to mesh so it's plausible that even this fluid movement has some impact on cognition.

Yes. I think scientists discovered within the last 10ish years that the brain has a lymphatic system at all. That kindof blew my mind, they they've only just discovered an anatomical feature of the brain? I find that kindof crazy, like, were they even looking?

> In living things, all the processes seem to mesh so it's plausible that even this fluid movement has some impact on cognition.

That sounds bang-on accurate, friend. That also makes the importance of exercise more obvious and subtle to me, walking being most gentle on the body but also requiring at least 30 minutes to really be "exercise". And, then, how good is the air being cycled in on those breaths. I imagine it's damn near impossible to find good air for lots of people who don't have a good tree-filled park close by. I have both seen the morning "green air cloud" hanging over Istanbul on the flight in, as well as the amount of smog on the ground in the morning. Returning to the US the first time visiting Turkiye I was immediately struck by the amount of greenery on the east coast here in the States.

They were, but ... if you don't know what to look for you probably don't find it!

Apparently it's not something you can simply dissect and point at it easily. (Otherwise people would have found it. Though it still happens from time to time that folks find new ligaments here or there in the complicated joints. But AFAIU the brain is much harder to preserve and prepare.)

https://pmc.ncbi.nlm.nih.gov/articles/PMC10546208/ -- here the study uses immunohistochemistry

Thanks, that's interesting. This shows the shallowness of my understanding:

> It has been known for centuries that the dura mater may harbor lymphatic vessels but the role of meningeal lymphatic vessels (MLVs) regained renewed interest since 2015, when functional MLVs were first reported.

Life is incredibly complex, ours most of all.

But finding new ligaments is really crazy.

I work in the neurotech/sleeptech space developing slow-wave enhancement technology.

Previous studies have looked at how increased slow-wave activity (delta power - a measure of the synchronous firing of neurons which define deep sleep) effects the removal of amyloid and other metabolic waste from the brain[1].

As I work with closed-loop stimulation, not pharmaceuticals, I wasn't familiar with the connection between norephedrine and slow-wave sleep, and my quick search has not cleared up how this researcher made that connection - as the counter argument in the article states.

If you're curious about slow-wave enhancement and improving the restorative function of the brain, you can find out more on our website https://affectablesleep.com

[1]https://academic.oup.com/ageing/article/52/12/afad228/750330...

I find that even a quite brief nap (on the order of one to three minutes) is still tremendously refreshing. Is this enough time for this fluid dynamic under study to gear up and get some flushing done ? Or would it be some other mechanism.

Some animals get most if not all of their sleep through microsleep [1]. So whatever mechanism "refreshes" the brain, it can work on short time scales. The switch in brain firing dynamics from wake to sleep (NREM) is very fast -- on the order of one to a few seconds. People in team Nedergaard argue that it is the rhythmic neuronal activity during sleep that promotes fluid flow (though to be fair, some argue its arterial pressure). So their answer to your question would be yes, that should be enough time to enhance fluid flow (fluid is flowing all the time, the question debated by scientists is, whether is it being enhanced during sleep).

[1] https://www.science.org/doi/10.1126/science.adh0771

I wonder how much of an effect physical brain size has on this. Square-cube law and all that. Bird brains are famously small (though highly efficient).

I don't think that translates to humans. Sleep disturbances like the micro-arousals triggered by sleep apnea absolutely ruin lives, way before lack od oxygen becomes a problem. Arousals destroy sleep architecture. Humans cannot thrive on microsleep.

I've felt my brain flush, dunno if anyone else has.

For me it feels more like a rinse.

My brain feels cloudy/covered in junk. Then I rest and can kind of feel all the crap being hosed away

Same, I can even feel which general areas don't feel rinsed enough when I don't get enough sleep, although I can't be sure if it's the accurate location or merely the position the sensor data gets reported to.

Sometimes I hear a 10-20hz pulsing sound (so pretty fast, chirping sound) emanating from around my brainstem / back of neck at the level of my ears and a slight feeling of some liquidy movement inside. I always thought it was connected to CSP movement but maybe it isn't. But if it isn't I can't see what else it can be as it happens when I'm completely stationary.

Agreed. For me turning over in bed during a lie-in also feels immensely refreshing and I now do it quite consciously. It may be nothing to do with cerebrospinal fluid but I do like to attribute it to the brain's wash cycle.

I don't think the brain relies on a spin cycle like a washing machine, but maybe it's not so far fetched. Walking and being generally active helps the body "pump" lymph.

My go-to analogy is a movie theater. Once in a while you have to break out the firehouse and wash down all the accumulated popcorn, gummy bears, dried-up soda pop, and tracked-in dirt. And no, it cannot all be recycled to make new movietime snacks.

Great article as an outsider just to understand a bit what the open questions are in studies of the brain and how these open questions get discussed by researchers. Very easy to read and fascinating.

"there was more movement of cerebrospinal fluid (opens a new tab) in sleeping and anesthetized mice than in waking ones"

Does this have implications for people in long-term medical comas?

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