Women More Likely to Be Affected by Moyamoya Disease

Women are more likely than men to be affected by Moyamoya disease (MMD), have a higher risk of initially presenting with a transient ischemic attack (TIA), and are about twice as likely to have an adverse postoperative event, according to a new study.

Researchers at Stanford University (CA, USA) examined a large series of 433 consecutive MMD patients (mean age of 31 years) to determine whether sex differences exist in presentation and treatment outcomes after cerebral revascularization. Preoperative evaluation of the patients included clinical presentation, cerebral magnetic resonance imaging (MRI), 6-vessel angiography, and perfusion studies. All 433 patients underwent 724 revascularization procedures between 1991 and January 2010 by a single physician. The postoperative evaluation included similar studies at a minimum of 6 months, and then at 3 and 10 years. New events and neurologic deficits associated with a new infarct or hemorrhage lasting 24 hours or longer after revascularization surgery were recorded; abilities to perform activities of daily living were gauged using the modified Rankin Scale (mRS).

The study results for 403 evaluable patients involved 717 revascularization procedures. The researchers found that the female to male ratio was 2.5:1 (307 females to 123 males). No differences between sexes were found for race or ethnicity (58.6% white and 30.9% Asian), hypertension, smoking history, or hyperlipidemia. Men and women were equally likely to present with ischemic or hemorrhagic strokes, headaches, or seizures. Postoperatively, both men and women showed significant improvement on the mRS. Postoperative adverse events in occurred in 40 patients (9.9%) and included hemorrhage and ischemic stroke. A Kaplan-Meier analysis of event-free survival suggested that women were at twice the cumulative risk for an adverse event at 5 years from their first surgery: 11.9% for women compared to 5.3% for men. The study was presented at the American Association of Neurological Surgeons annual meeting, held during May 2010 in Philadelphia (PA, USA).

"The females in our cohort were more likely to present with TIAs than the males. That may be important because that may give us a clue as to how the disease is acting preferentially in women versus men,” said senior author and study presenter Gary Steinberg, M.D., Ph.D., chairman of neurosurgery and professor of neurosurgery and the neurosciences at Stanford. "About half of those patients recover completely. No hemorrhage has ever been seen at the site of anastomosis of the vessels.”

MMD is a rare, progressive cerebral angiopathy in which the main arteries of the brain, the internal carotid, anterior, and middle cerebral arteries, as well as the circle of Willis, are narrowed or occluded bilaterally, probably from migration and proliferation of vascular smooth muscle cells within the arteries, causing TIAs. Loss of function manifests as limb weakness, sensory disturbances, epileptic seizures, or headaches. Thin, weak collateral vessels form in the brain in reaction to the occlusions. These vessels, prone to hemorrhage, aneurysm, and thrombosis, form a cloudlike appearance on radiographic imaging, giving the disease its name, "moyamoya,” which in Japanese means "puff of smoke.”

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