The Science of Yoga

essence, Russell was now asking if the same thing was happening with yoga.
    His alert proved timely. Perhaps he was simply ahead of his day, or perhaps his warning opened the eyes of colleagues, or perhaps the growth of yoga was resulting in more injuries. For whatever reason or reasons, an American physician in the following year, 1973, made public a gruesome case study. The author was Willibald Nagler. He worked on Manhattan’s Upper East Side atthe Weill Medical College of Cornell University. A world authority on spinal rehabilitation, he had counted President Kennedy among his patients.
    In his report, Nagler described how a woman of twenty-eight, “a Yoga enthusiast” as he called her in the sketchy anonymity of clinical reports, had suffered a stroke while doing a position known in gymnastics as the Bridge and in yoga as the Wheel or Upward Bow (in Sanskrit Urdhva Dhanurasana). The posture begins with the practitioner lying on his or her back and then pushing up, balancing on the hands and feet and lifting the body into a semicircular arc. An intermediate stage can involve raising the trunk and resting the crown of the head on the floor.

    Wheel or Upward Bow, Urdhva Dhanurasana
    Nagler reported that the woman entered her crisis while balanced on her head, her neck bent far backward. While so extended, she “suddenly felt a severe throbbing headache,” he reported. She had difficulty getting up. After she was helped into a standing position, she was unable to walk without assistance.
    The woman was rushed to the hospital and found to be experiencing a number of physical disorders. She could feel no sensations on the right side of her body. Her left arm and leg wavered. Her eyes kept glancing involuntarily to the left. And the left side of her face showed a contracted pupil, a drooping upper eyelid, and a rising lower lid—a cluster of symptoms known asHorner’s syndrome. Nagler reported that the woman also had a tendency to fall to the left.
    Diagnostic inquiry showed that her left vertebral artery had narrowed considerably between cervical vertebrae C1 and C2, revealing the probable site of the blockage that resulted in the stroke. It also showed that the arteries feeding her cerebellum (the structure of the rear brain that coordinates the muscles and balance) had undergone severe displacement, hinting at trouble within. Given the day’s lack of advanced imaging technologies, an exploratory operation was deemed necessary to better evaluate the woman’s injuries and prospects for recovery.
    The surgeons who opened her skull found that the left hemisphere of her cerebellum had suffered a major failure of blood supply that resulted in much dead tissue. They also found the site seeped in secondary hemorrhages, or bleeding. In response, the physicians put the woman on an extensive program of rehabilitation. Two years later, she was able to walk, Nagler reported, “with broad-based gait.” But her left arm continued to wander and her left eye continued to show Horner’s syndrome.
    Nagler concluded that such injuries appeared to be rare but served as a warning about the hazards of “forceful hyperextension of the neck.” He urged health professionals to show caution in recommending such difficult postures to individuals of middle age.
    The next case came to light in 1977. The man of twenty-five had been in excellent health and doing yoga every morning for a year and a half. His routine included spinal twists in which he rotated his head far to the left and far to the right. Then, according to a team in Chicago at the Northwestern University Medical School, he would do a Shoulder Stand with his neck “maximally flexed against the bare floor,” echoing Iyengar’s call for perpendicularity in Light on Yoga. The team said the young man usually remained in the inversion for about five minutes.
    One morning upon finishing this routine, he suddenly felt a sensation of pins and needles on the left side of his face. Fifteen minutes later, he felt dizzy and his vision blurred. Soon, he was unable to walk without assistance and had trouble controlling the left side of his body. The man also found it difficult to swallow. He was rushed to the hospital.
    Steven H. Hanus was a medical student at Northwestern who became fascinated by the case. He took the lead and worked with the chairman of the department ofneurology to elucidate the exact cause of the disabilities, publishing a study with two colleagues when he