Thursday, May 21, 2009

Might MVPS Originate with Sleep Apnea?

As I speculated in this posting, MVPS and sleep apnea may reinforce one another. But when I recently discovered this report from 2005 by David L. Detrick, M.D. of the High Desert Sleep Disorders Center, I started to question whether, in fact, MVPS is the visible manifestation of sleep apnea on the sympathetic nervous system.

It's not the most readable document for the lay person, but anyone with basic physiology education will understand from the numbers and charts that, in fact, MVPS has substantial overlap with the neurological symptoms of sleep apnea. Granted, sleep apnea is primarily due to physiological impairments which affect proper breathing during sleep. However, as the report illustrates in substantial detail, the resulting intermittent hypoxia induces increased sympathetic nervous system function -- not merely related to individual hypoxic episodes, but increasingly persistent into daytime physiological stress metrics, including blood pressure, oxidative stress, and hormone levels.

Granted, not all MVP sufferers have MVPS. But for those who have the latter, I would highly recommend a sleep study in order to look for sleep apnea. (Because it is a diagnostic procedure like an xray, you insurance may cover most or all of the cost.) Sleep apnea is a stealth disease, in the sense that it may result in few detectable symptoms early on. It's also very treatable, with or without surgery. But when ignored, it's a serious risk factor for cardiovascular disease, stroke, and accidental death due to impaired alertness.

I definitely believe that MVP and sleep apnea are separate diseases with different causes. But when they coexist in a patient (which I suspect occurs more than randomness would dictate, on account of their mutual reinforcement as detailed in my earlier post), then the latter may produce the physiological syndrome which we know as MVPS. In the absence of MVP, the syndrome is simply regarded as the physiological side effects of sleep apnea.

My original thinking was that MVPS and MVP are parallel results of a single set of genetic errors. But, to summarize, I now suspect that MVPS may be the result of sleep apnea. We only think of it as being directly related to MVP because -- I suspect -- that MVP is coincident with sleep apnea more than randomness would dictate.

Some experiments would need to determine whether (1) to what extent MVPS sufferers have sleep apnea, vs. control and (2) to what extent MVPS symptoms subside pursuant to a few months of CPAP use. (A CPAP is a respiratory assistance device for the treatment of sleep apnea.)

If I'm completely wrong, then hopefully I will at least save a few lives by encouraging people to detect and treat sleep apnea before they suffer a stroke or heart attack.