Researchers analyze role of gender in treatment and outcome of patients with MMD

Moyamoya disease (MMD) is an uncommon, progressive cerebrovascular disease in which the main arteries feeding the brain (the intracranial internal carotid arteries/ICA and Circle of Willis) are narrowed or occluded on both sides, reducing blood flow to the brain. This causes transient episodes of reversible stroke (TIAs) with loss of neurologic function in the form of weakness of a limb, sensory disturbances, epileptic seizures or headaches. If this continues, the brain can suffer an irreversible "stroke" with permanent loss of neurologic function and disability. If left untreated in children, MMD can result in a child becoming cognitively impaired, unable to speak, and wheelchair bound.

MMD was first described in Japan in 1956 and has been known to exist mainly in Asia, although in recent years with increasing awareness, more cases are being diagnosed in the U.S. and Europe. Once properly diagnosed, the goal is to prevent stroke and its consequences by performing revascularization surgery called extracranial to intracranial bypass (EC-IC bypass). This enables extra blood from scalp arteries to reach the brain areas suffering from inadequate blood supply.

The exact cause of MMD is unknown. Some genetic predisposition is apparent because it is familial 10 percent of the time. There is a higher prevalence of MMD in women across different demographic populations, although specific gender differences in stroke incidence and clinical outcomes with and/or without surgery have not been studied.

Researchers at Stanford University School of Medicine analyzed the role of gender in the treatment and outcome of patients with MMD. The results of this study, Gender Differences in Clinical Presentation and Treatment Outcomes in Moyamoya Disease, will be presented by Nadia Khan, MD, 5:19-5:25 pm, Tuesday, May 4, 2010, during the 78th Annual Meeting of the American Association of Neurological Surgeons in Philadelphia. Co-authors are Achal S. Achrol, MD, Raphael Guzman, MD, Robert Dodd, MD, PhD, Teresa Bell-Stephens, RN, and Gary K. Steinberg, MD, PhD.

The group of patients at Stanford is the largest series of surgically treated MMD patients in a single, North American institution. All patients underwent surgery performed by one neurosurgeon during an 18-year period (1991-2009). "This presented an extraordinary opportunity to clinically analyze whether gender plays a role in clinical presentation and treatment outcomes following revascularization surgery on a very large scale," stated Dr. Khan.

•There were 433 MMD patients who underwent 724 revascularization surgeries

•By gender: 309 females, 124 males

•Mean age at surgery: 30 years

Clinical findings by gender elucidated in this study:

•Female MMD patients had a two-fold higher risk of developing TIAs as a presenting symptom than males.

•Females had a three-fold higher risk of adverse postoperative events than males.

•Five-year cumulative risk of adverse postoperative events: 8.3 percent in females versus 2.7 percent in males.

Both males and females experienced significant clinical improvement following surgical revascularization at a mean follow up of 4.6 years. "This data supports surgical revascularization as beneficial to both groups, despite the trend toward a higher rate of adverse postoperative events in females. The importance of early clinical evaluation, diagnosis and prompt surgical intervention is clearly essential, but the exact role of gender-related influences in the pathophysiology of MMD needs to undergo further studies," concluded Dr. Khan.