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When Simple Actions Ravage Arteries

April 3, 2001

By JANE E. BRODY

Martin Dunitz, a London publisher of medical texts, is one lucky man, if you can call anyone who has suffered damage to one of the two arteries that feed the brain lucky. While on a Caribbean vacation with his wife and two daughters in St. Lucia, Mr. Dunitz went water-skiing.

Hours later he developed severe pain behind one eye and a strange distortion and numbness of his mouth and tongue that made it very difficult to eat and talk. Not wanting to disrupt the vacation, Mr. Dunitz waited until he got home to London to see a doctor. He even went water-skiing a second time.

Though one doctor thought he had Bell's palsy, a usually temporary paralysis on one side of the face, Dr. Martin Rossor, a neurologist at the National Hospital for Neurology and Neurosurgery in London, immediately suspected something far more serious: a tear, or dissection, of the carotid artery feeding the brain, resulting in a leakage of blood that could easily have precipitated a full-blown stroke. The suspected diagnosis was confirmed by magnetic resonance imaging, an M.R.I.

Mr. Dunitz is lucky because his arterial trauma did not result in a stroke and with about six months of treatment with anticoagulants, he is expected to make a full recovery. Not everyone who has suffered a dissected carotid or vertebral artery has been as fortunate.

In February 1998, for example, a 20-year-old woman from Saskatchewan lapsed into a coma on a chiropractor's table and died 24 hours later. She had sought treatment for a stiff neck and, after neck manipulation by the chiropractor, a dissection of a vertebral artery caused an aneurysm that interrupted blood flow to her brain.

Likewise, a 35-year-old mother of four in Seattle suffered a stroke precipitated by a dissected vertebral artery immediately after chiropractic manipulation. She survived but now struggles with simple everyday tasks like tying her shoes.

An arterial dissection starts with a tear inside one of the major arteries in the neck. This allows blood to enter the wall of the artery and split its layers, resulting either in the formation of a clot or in an aneurysm (a pouch sticking out from the blood vessel), possibly disrupting blood flow to the brain and damaging cranial nerves.

Why Does This Happen?

Arterial dissections were once thought to be extremely rare and were usually detected only at autopsy. But with the aid of modern diagnostic techniques like CT scans and especially M.R.I.'s, neurologists are now discovering them more often. In a report March 22 in The New England Journal of Medicine, Dr. Wouter I. Schievink of the Cedars-Sinai Neurological Institute in Los Angeles reported an annual incidence of 1 per 100,000 to 1.5 per 100,000 people. While these dissections account for only about 2 percent of all nonhemorrhagic strokes, they are an important cause of stroke in young and middle-aged patients, accounting for as many as one-quarter of cases in these age groups.

Chiropractic spinal manipulation, estimated to cause strokes in as many as one in 20,000 patients who undergo it, is but one possible cause. Any sudden, abrupt neck movement or extreme neck position can cause an arterial dissection in a susceptible person. Other situations include getting one's hair washed in a beauty salon (the so- called beauty-parlor stroke) or drinking a shot of whiskey (dubbed the "bottoms-up dissection") or lifting heavy objects. A champion swimmer developed a dissected carotid from doing too much backstroke.

Dr. Schievink also lists precipitating events associated with hyperextension of the neck, including "practicing yoga, painting a ceiling, coughing, vomiting and sneezing," as well as medical procedures like receiving anesthesia or being resuscitated and traumatic causes like motor vehicle accidents or sports injuries.

An estimated one-fourth of patients who suffer an arterial dissection after chiropractic manipulation are believed to have an underlying connective tissue disorder or structural defect of the arterial wall that increases their vulnerability to arterial damage. In fact, it has been suggested that the early symptoms of vertebral-artery dissection, which commonly mimic musculoskeletal neck pain, may be what prompt people like the 20-year-old Canadian woman to visit a chiropractor in the first place.

There may also be an infectious factor in some cases, since the occurrence of carotid and vertebral artery dissections with no apparent cause peaks in the fall, when respiratory infections are most common.

Delay Is Dangerous

It is critically important to respond quickly to the early warning signs of an arterial dissection. The spectrum of symptoms varies from patient to patient and is determined in part by which artery is affected. In patients with a dissection of the internal carotid artery, for example, typical symptoms include pain on one side of the head, face or neck accompanied by paralysis of one eye and followed hours or days later by brain or retinal symptoms.

Other common symptoms of arterial dissections are pain in the back of the neck or head, a constant headache that develops suddenly on one side of the head and that may resemble a migraine, pain behind an eye, impaired ability to taste, tinnitus (pulsing noises in an ear), temporary visual loss and temporary loss of awareness (a kind of ministroke called a transient ischemic attack).

Anyone who develops two or more such symptoms should seek medical care without delay and, to enhance the likelihood of a speedy and correct diagnosis, perhaps even suggest that the doctor investigate the possibility of an arterial dissection by performing a magnetic resonance angiogram.

Carotid and vertebral artery dissections are fatal in fewer than 5 percent of cases, and about three-fourths of patients who suffer a stroke as a result of a dissection make a "good functional recovery," Dr. Schievink reported. Most dissections heal without surgery, blockages gradually resolve in 90 percent of cases and one-third of aneurysms decrease in size. There is, however, a small risk that once there has been an arterial dissection, the disorder will occur in another artery.

Treatment involves preventing the complications of clots by administering anticoagulants, at first intravenously and then orally for three to six months. Patients must have their blood checked often to be sure it does not become too thin because overly thin blood can result in a hemorrhage.

When conservative treatment fails to correct the problem, a balloon may be inflated in the affected artery to compress the clot and a metal stent inserted to keep the artery open. With this modern therapy, surgery to bypass the damaged artery has become far less common.

Copyright 2001 The New York Times Company