I'd think of a title if it wasn't for this sinus pressure

December 12, 2010 4:36 PM

As I suffering through another sinus infection, in my lucid moments I wonder: What causes the brain fog that goes with a sinus infection?

Is it as simple as sinuses pressing against the brain? Or is there something else involved?

posted by ShooBoo to Health & Fitness (10 answers total)

I read an article some years ago on research into the body's immune system response to viral infection, and efforts to enhance this by boosting interferon and some other stuff that I can't remember.

The results were promising, but the downside was the patient suffered much worse symptoms [aching joints, chills, headache & generally feeling grotty]. They concluded that most of the symptoms from colds & flu arise not from the infection itself, but from the immune system fighting it off.

So, I can't be sure this is an issue with your sinus infection, but it is a possibility.
posted by HiroProtagonist at 4:52 PM on December 12, 2010

I wonder: What causes the brain fog that goes with a sinus infection?

Ugh, me too. The fatigue/brain fog combo does seem unique to sinus infections, at least for anything I've so far experienced in my life. My totally uninformed guess is:

The sinus infection generates local immune system and inflammation factors that diffuse to the nearby brain, causing some inflammation and unhappiness in brain tissue. But the blood-brain barrier might keep a lot of that stuff out, if not all of it. So, I don't know.
posted by zeek321 at 4:59 PM on December 12, 2010

I don't get sinus infection issues, so I don't know if that's related to the flu/common cold brain fog. My pet neurological theory is that the dopamine levels in the system go down, but if that's true I don't have any idea why that happens -- or maybe that's how the body forces one to rest and the brain fog and irritability is a side effect. Also side effects from any medication taken shouldn't be ruled out -- antihistamines can have a sort of brain fog effect (the 70s antihistimine du jour Actifed comes to mind).
posted by crapmatic at 5:21 PM on December 12, 2010

I'm voting for it being some wacky biochemical side-product of inflammation, too.

I know there are MeFites in the relevant research disciples...trying to remember who to page. (Made more difficult by the current plague from which I'm suffering.)
posted by desuetude at 5:25 PM on December 12, 2010

Don't know the biochemistry (but probably this), but natural selection would say that it got bred in so that you would go into the cave/nest and suffer quietly, rather than be out there in the wild at less than 100% and get eaten by a tiger.
posted by gjc at 5:54 PM on December 12, 2010

Intercranial pressure and paranasal sinuses. Your sinuses aren't in the right spot to press against your brain. On top of that, your body can regulate the fluid around your brain in order to keep the pressure inside your skull constant. If this stops working and your intercranial pressure does increase, it's usually a serious, serious, serious medical emergency.

The fatigue is a sickness behaviour, which in theory keeps you resting so that your body can spend all of its energy fighting the infection. (What gjc said.)
posted by anaelith at 5:57 PM on December 12, 2010 [3 favorites]

If the inflammation did spread to the brain, that would be called meningitis or encephalitis. Both of these are much more serious medical emergencies than a sinus infection.
posted by Nomyte at 6:51 PM on December 12, 2010

According to the wikipedia article on fever, one of the symptoms, among others, is the inability to concentrate. Do you normally get a fever when you have a sinus infection? Also, sinus pain is pretty excruciating in my experience, and any pain of that caliber is enough to put someone in a state of "brain fog". As in, all you want to do is be drugged and sleep in a very dark room, probably under the covers. I hope you feel better!
posted by two lights above the sea at 7:11 PM on December 12, 2010

Any chance you're not getting enough air? I don't know what sinus infections are like, but the last time I had a common cold I ended up with asthmatic complications. Before I went to the doctor and knew what was going on, I felt constantly tired, unmotivated, and certainly couldn't think very clearly (which was a problem when it came to any math more complicated than simple algebra at work). It turned out that the levels of oxygen in my blood were remarkably low, which explained, among other symptoms, the confusion.
posted by halogen at 7:47 PM on December 12, 2010

I would think that it is related to interferon production. Interferons, especially type I interferons, are readily produced in all inflammatory reactions. Sustained interferon production results in fever, but I think you can get interferon-related symptoms before then. Due to its antiviral properties, Type I Interferon is used as a therapeutic in a number of infections. It's effective, but comes with some pretty awful side effects, including a number of neurological symptoms. Harmful Brain Effects of Interferons.
posted by kisch mokusch at 1:51 AM on December 13, 2010