The drug known on the streets as crystal meth could increase the risk of stroke and major tears in neck arteries, neurologists report.

With help from his colleagues, neurologist Wengui Yu, now at the University of Texas Southwestern Medical Center at Dallas, examined two women, ages 29 and 36, both of whom used methamphetamine and then suddenly experienced weakness and difficulty in speaking. Brain scans revealed both women had suffered severe strokes from tears in the inner lining of one of the major arteries in the neck, an injury known as carotid artery dissection.

On the National Institutes of Health Stroke Scale, a score over 16 suggests a high chance of death or severe disability. The 29-year-old woman received a score of 17, while the 36-year-old woman received a 21. Besides methamphetamine abuse, the women did not have any other significant risk factors for stroke. Both recovered with mild to moderate disabilities after stroke therapy.

"The work they did was beautifully done and very carefully characterized," says stroke neurologist Steven Cramer of the University of California, Irvine. "If I ever see any young person with a stroke--that is, anyone under 65--I'll be sure now to do a toxicology screen early on in the evaluation."

Methamphetamine, an addictive stimulant, is known to increase blood pressure, constrict blood vessels and inflame or damage blood vessel walls. It has previously been linked with aortic dissections, which are tears in the walls of the aorta, the largest artery in the body. Yu notes that cocaine has effects on the body similar to those of methamphetamine, and is also linked with aortic and carotid artery dissections. This suggests tears in arteries may be an effect linked to a class of drugs rather than to a specific drug.

"If larger studies confirm these findings and the suspicions of many that this is not a rare process, this could open up an avenue for intervention when it comes to methamphetamine. It could prevent a rise in frequency in the expensive and disabling condition of stroke," says Cramer. Data from such studies could "help physicians to better diagnose, treat, and prevent stroke in young adults," says Yu.

Yu and his colleagues reported their findings in the December 26 Neurology.