YOU love those swatches of lustrous, flowing hair, but visits to the beauty salon may do more harm than good. After a year of extensive research on blood flow to the brain, New York-based neurologist Michael Weintraub found that the risk of stroke is far greater when the neck is arched or twisted into extreme positions -- as at beauty salons, when painting a ceiling or when undergoing prolonged dental work -- than was earlier believed.

According to Weintraub, 2 vertebral arteries extend from the heart to the back of the brain. These are encased in a bony tunnel formed by projections from the neck vertebrae. Due to their close proximity to the bones in the neck, says Weintraub, these arteries are twisted and compressed when the neck is bent in extreme positions, reducing blood flow to the brain.