Tuesday, March 18, 2008
Silent brain infarctions
...and no air through the airway means no oxygen to the brain!
Clinically identified stroke represents the tip of the iceberg in terms of cerebral vascular disease by at least an order of magnitude...It is hard to believe, however, that loss of brain tissue should go without consequences. The brain may reorganize functional networks to adapt to lesions and recover function. But with each subsequent stroke, the capacity to do so is diminished.
--Brian J. Murray, MD
Silent brain infarctions or SBIs occur when a small amount of brain tissue is lost due to a lack of oxygenated blood to the area caused by a blockage in its blood supply. While any one such event can pass unnoticed, the cumulative damage from many such events builds up over time until the loss is manifested by neurological symptoms such as confusion or unsteadiness with walking. Nursing homes are filled with old ladies who lost their independence piecemeal in just such a fashion.
Scary new news on SBIs--one-fourth of persons with obstructive sleep apnea (the bedmate who keeps you awake as you lie awake waiting for him to take his next breath) were found in a Japanese study to have evidence of extensive silent strokes on MRI imaging.
How do you know if you've got sleep apnea if no one is lying awake waiting for you to breathe, and then telling you about it in the morning? Excessive daytime sleepiness,* a high red blood cell count, hypertension, and a short, thick neck are often associated with this dangerous condition.
*As your oxygen levels drop off when you stop breathing, brain sensors rouse you to near consciousness to get you to make that big, annoying (to your bed partner) gasp for breath. While you may not be aware that you are waking up multiple times during the night, the lack of deep levels of sleep leaves you heavy-lidded by early afternoon.