From a concerned Yoga teacher:
A student brought a New York Times article to me, from October 9, 2011, p.11, a column by Maureen Dowd. She quotes the Times Science writer, William Broad, Yoga has produced waves of injuries. Take strokes..Doctors have found that certain poses can result in brain damage that turns practitioners into cripples, with drooping eyelids and falling limbs.
Is this true? Is there any evidence of this? The book is entitled,The Science of Yoga: the Myths and the Rewards.
The New York Times article mentioned is a free read online here. Broads book, a description of which can found here, looks like it will be entertaining when it arrives on the shelves in February.
While there is some truth to what the book author writes about Yoga and injuries, there is certainly a sensationalistic tone that exaggerates reality.
As with any movement anyone can do at any time, there is a risk of injury with Yoga.
Even simply walking, a normal activity most of us do everyday, can result in stubbed or broken toes, banged shins with bleeding lacerations, sprained ankles, and even serious head trauma if one falls and hits their head on a hard surface. Ive seen all these walking injuries working in the ER. I havent seen Yoga injuries – but thats because way more people walk than do Yoga. As Yoga becomes more popular, the increasing numbers of people participating will lead to waves of injuries showing up in emergency rooms that werent seen before.
One must be careful. Mindfulness is part of Yoga, and being mindful of proper slow transitions and postures prevents most injuries. Never force a posture, and never let a teacher push you into one. Some modern Yoga styles are more like aerobics or calisthenics, and with those increasingly aggressive styles focused on rapid strenuous exercise, injuries are more likely to result. The modern trend of turning Yoga into a sport results in typical sports-related injuries.
Specifically regarding stroke, there is some circumstantial evidence that neck extension, particularly neck extension with rotation, can lead to stroke. Avoid hyperextending and dont roll the head around from side to side while looking way up at the ceiling.
These movements are not unique to Yoga. Originally this type of stroke was called beauty parlor syndrome (because of the extension of the neck over the shampoo bowl with movement side to side with rinsing). Its been reported with playing volleyball and tennis (think serving with the head thrown way back to look up at the ball), painting the ceiling, throwing back shots of liquor, and even driving (looking back and up over the shoulder with reverse).
An explanation of how such movements can cause a stroke is discussed in a previous post here. Basically, the motion of full extension of the neck with rotation can trap a vertebral artery that runs inside a small hole in each of the bones of the neck, lacing them together (see diagram above). If they get caught or snagged on a bone fragment and then stretched, a tear in the inner lining of the blood vessel wall can occur – and then dissection and stroke.
There are less than a handful of case reports in the medical literature specifically implicating Yoga as a cause of stroke over the past forty years. I emphasize that they are case reports, not prospective studies. Since vertebral and carotid dissections usually present with symptoms several hours after the causal injury, it is a bit of a guessing game to determine exactly what movement caused the injury and when. This type of stroke, a large artery dissection, is quite rare, and determining the exact cause is difficult and inexact. The few strokes thought to have been caused by Yoga may not have been.
Here are two articles Ive written in the past addressing Yoga and stroke:
Can Yoga Cause a Stroke?
Sirsasana: Can You Bleed From the Headstand?
While the link between Yoga and strokes is tenuous, its best to be cautious. Don’t throw the head back too far into hyperextension, and don’t roll or rotate the head when the neck is in extension (when the face is pointed towards the ceiling).