Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, May 10, 1994 TAG: 9405100108
SECTION: EXTRA PAGE: EXTRA1 EDITION: METRO
SOURCE: Jane Brody
DATELINE: LENGTH: Long
As is common practice when beauticians shampoo hair or neutralize a permanent wave, the women's heads were tipped back over the edge of the sink.
Now, after a year of detailed studies of blood flow to the brain, the neurologist, Dr. Michael Weintraub, believes that the risk of stroke and lesser forms of brain damage when the neck is arched or twisted in extreme positions is much greater than he had originally believed.
The hazard, he says, is not limited to older people and extends well beyond those who visit beauty salons.
Also at risk are young people born with a hidden malformation of a main artery leading to the brain. Damage from extreme neck positions can affect them if they undergo prolonged dental work, paint ceilings or do other work over their heads, are subjected to extreme chiropractic manipulations of the neck or are fitted with a breathing tube in surgery.
Each of these circumstances can place the neck in a position that greatly reduces blood flow through one or both of the vertebral arteries, Weintraub's studies have shown. The problem is especially likely to affect older people who have complicating factors like high blood pressure or diabetes, which make them more vulnerable to stroke.
When blood flow becomes sluggish, clots can form that are carried into the brain when normal blood flow is restored. These clots can block circulation to a part of the brain, causing a stroke. Weintraub suggested that this might account for the disproportionate occurrence of strokes during sleep or just after awakening.
In a report to be presented today to the annual meeting of the American Academy of Neurology, Weintraub is calling for doctors and potential patients to be alert to the warning signs of interrupted vertebral circulation, like dizziness or loss of balance when the neck is bent. He is also warning the elderly and anyone who already faces a higher than average risk of stroke to avoid extreme neck positions.
Vulnerable arteries
The two vertebral arteries carry oxygen-rich blood from the vessels leaving the heart up to the back of the brain - the brain stem, cerebellum and thalamus - as well as to parts of the spinal column. They are called vertebral arteries because where they rise through the neck they are housed in bony tunnels formed by projections from the sides of the cervical vertebrae. Together they are responsible for carrying 20 to 25 percent of the blood that reaches the brain. (The remaining 75 to 80 percent of the brain's blood supply comes from the large carotid arteries in the front of the neck.)
Because the vertebral arteries are next to the bones of the neck, they are easily twisted and compressed when the neck is bent in extreme positions. The risk is especially great in people born with an underdeveloped vertebral artery or who develop shifting of the neck bones or bony protuberances on the cervical vertebrae, which can displace or compress a vertebral artery even when the neck is not bent or turned.
The elderly are especially at risk because with age all major arteries tend to become clogged with fatty deposits that reduce the passageway through which blood must flow. The elderly are also more likely to have arthritic changes in their necks and irregular bony spikes on their cervical vertebrae, both of which can increase the risk of vertebral artery compression when their necks are turned in ways that caused no trouble in their younger years.
In last year's report in the April 28 issue of The Journal of the American Medical Association, Weintraub described the cases of the five women who required hospitalization for severe neurological disturbances and stroke after shampoos in beauty parlors. He attributed the damage to ``mechanical impingement'' of blood flow through one or both vertebral arteries when, during the shampoos, their necks were arched back so that their chins pointed toward the ceiling.
Just a month before his report, 10 cases of stroke after anesthesia administered with the neck in an extreme position had been described in the journal Neurology. When anesthesiologists insert the tube that maintains lung function during surgery, they temporarily arch the neck far back to straighten out the airway. But sometimes the neck is kept in that position throughout the surgery, which could last for hours.
During the procedure, the anesthesiologist is not likely to be aware of any problem because patients under anesthesia cannot complain when they experience neurological symptoms like dizziness or imbalance as a result of disrupted circulation to the brain.
The new studies
To document the nature of the problem and further define its extent, Weintraub, who is chief of neurology at Phelps Memorial Hospital in North Tarrytown, N.Y., and a clinical professor of neurology at New York Medical College in Valhalla, undertook detailed studies of blood flow to the brain when the necks of older men and women were twisted or arched in extreme positions. He has so far completed his studies on 40 people who had prior symptoms suggesting a vulnerability to brain damage and 30 people of similar age who had no symptoms.
The group of 40, ranging in age from 55 to 95, had experienced symptoms like vertigo, double vision, loss of balance or numbness on one side of their bodies at some time during the month before the study. These are indications that they may have already suffered mini-strokes or transient ischemic attacks, which are warning signs of a future stroke.
Weintraub used a technique called magnetic resonance angiography, a method that without a dye or penetration of body parts allowed him to track the flow of blood through the vertebral arteries as the position of the neck was changed.
He showed that as the necks of patients with symptoms were moved to one side, chin to shoulder, the vertebral artery was compressed, there was a marked decline in blood flow and symptoms of dizziness occurred in 70 percent. But in those who had no previous symptoms, only 13 percent experienced dizziness during the brief manipulation. Women in the symptomatic group experienced the most severe compression of the vertebral artery during the study.
What to do
Weintraub and other experts suggest that elderly people and especially those of any age who have experienced dizziness or loss of balance when the neck is bent, should avoid activities that demand extreme neck positions.
For example, hair can be washed with the head bent forward instead of back. The dental chair, instead of the patient's head, can be tilted way back. The anesthesiologist should be reminded to restore the patient's head to a normal position as soon as the tube is inserted.
People already at high risk for stroke - those who are obese, have high blood pressure, heart abnormalities, diabetes or smoke cigarettes - might consider wearing a cervical collar while sleeping, the neurologist suggested.
by CNB