By Vernon Rowe, M.D.
When the whole brain becomes swollen, without any signs of infection, stroke, or tumor, headaches are frequently the main clinical symptom, and swelling of the optic nerves can be seen on examination of the back of the eye with an ophthalmoscope. This condition is called “Pseudotumor” or Idiopathic Intracranial Hypertension.
Swelling of the optic nerves, or papilledema, can lead to loss of vision, if left untreated. Treatment consists of diuretics and medications to decrease the production of spinal fluid so the brain will shrink. The cause of this disorder until recently has been thought to be a reaction to various types of medications, like tetracycline.
Recently, however, a strong association with Obstructive Sleep Apnea has been noted, and as the methods we use to do a sleep study have become more sensitive. The question is why? Is sleep apnea the cause of pseudotumor?
An article by Wardly Medicalhypoth 2014 Intracranial Hypertension and OSA suggests many reasons why OSA may be the cause of pseudotumor. The first is that the return of venous blood from the brain through the jugular system can be impaired by excess fatty tissue in the necks of overweight people. Abnormal anatomy can lead to the same problem, though, in mouth breathers and people with elongated jaws. Also, even in slender people with hypermobility syndrome, extension of the neck at night to breathe can lead to headache, though rarely to pseudotumor. (link to poster)
Another way OSA can lead to pseudotumor is by possible excess neuro-excitability, or neuro-excitotoxicity. In OSA, there is excess glutamate and this over-stimulation leads to the death of cells in the memory structures of the brain, and to brain swelling. CPAP can reduce some of the resultant brain swelling seen in these patients, though careful titration must be done.
In addition, people with OSA have so-called “hypercoagulability”, where blood forms clots more easily than in normal people. This is caused by increased clotting factors, and these can be reversed by CPAP treatment. If left untreated, increased clots form in the veins and arteries, which can lead to stroke and heart attack.
Lastly, the barrier between the blood and the brain, the “blood-brain barrier,” so important in keeping unwanted chemicals out of the brain, can be broken down in OSA. Treatment of OSA with CPAP has been shown to restore the barrier.
So treatment of OSA is important for improvement of brain function and its protection against unwanted chemicals present in the blood, byproducts of the unhealthy food we eat sometimes, and the stress we all have in our lives. OSA disrupts sleep, makes us tired during the day, and causes automobile accidents, stroke and heart attacks. But sometimes it causes an increase in brain pressure at night, just when the brain is trying to repair itself. So even milder sleep apnea, even in young people, is not a good thing and should be treated.
All this suggests that even mild sleep disordered breathing, as present in many patients with Hypermobility Spectrum Disorder, can lead to deleterious effects on the brain and the central nervous system.