Most yogis accept the risk of occasional aches, pains, or minor injuries as being part of a committed practice. But stroke? A recent review in The New England Journal of Medicine (March 22, 2001) lists yoga as an activity that may trigger an unusual type of stroke called arterial dissection.
The review's author, Wouter I. Schievink, M.D., a neurosurgeon at Cedars-Sinai Maxine Dunitz Neurological Institute in Los Angeles, says poses such as inversions (Shoulderstand and Headstand), Parsvakonasana (Side Angle Pose), Trikonasana (Triangle Pose), and Halasana (Plow Pose) were specifically highlighted because they can result in sudden neck movements or put extreme pressure on the neck. Other situations mentioned include chiropractic adjustments, hard sneezes or coughs, and even relaxing into a beauty salon's sink.
Here's how arterial dissection occurs: A rapid rotation or hyperextension of the neck tears a small hole in the lining of one of its two main arteries. Blood seeps into the pocket, causing a clot to form. The clot expands, like a balloon, until blood flow to the brain is stifled and a stroke ensues.
Sufferers may mistake arterial dissection for a migraine or muscle tension. Symptoms often include a piercing pain in the back of the neck; a pounding, one-sided headache; loss of taste; partial facial paralysis; or ringing in the ears. Warning signs can intensify for hours or even days before a stroke hits.
But don't cancel your next yoga session just yet. Arterial dissection is rare and strikes roughly 1.5 out of every 100,000 Americans annually, according to Schievink, with yoga being the culprit in a minuscule number of cases.
However, while arterial dissection accounts for just 2 percent of total strokes, it is one of the main causes of stroke in young and middle-aged people. In those 50 and younger, it accounts for up to 25 percent of strokes. Also, arterial dissection is not linked to atherosclerosis—the hardening of the arteries due to fatty deposits and cholesterol—which means it can strike people who maintain a healthy diet. In most incidences, it affects those who have a genetic predisposition to weakened blood vessels, says David Simon, M.D., medical director of the Chopra Center for Well Being in La Jolla, California. Yet, more times than not, there's no way to discover this defect until it's too late.
Although the condition is hard to diagnose because of its rarity, treatment is simple and recovery rates are high. After an extended course of blood thinners, roughly 75 percent of people make a "good functional recovery," according to the report. Death results in less than 5 percent of cases.
So, what can yogis do to protect themselves? "Listen to your body," says Simon. "Move into and out of asanas smoothly and slowly. Avoid thrusting, jerking movements. Go up to the point of resistance, but never push past it." Simon also says to avoid putting excessive weight on your neck in poses like Matsyasana (Fish Pose), Halasana, or Headstand, especially if you're a novice. "The benefits of yoga outweigh the risk of arterial dissection," he says. "Taking a commonsense approach lowers those odds even more."