30 March 2012
Neurosurgery 2012; Advance online publication
MedWire News: The diagnosis of moyamoya disorder and associated ischemic stroke has increased over recent years in the USA, say researchers who characterized a large cohort of patients.
Using the US Nationwide Inpatient Sample, Robert Starke (University of Virginia, Charlottesville, USA) and colleagues identified 2280 patients with moyamoya disorder admitted to hospital during 2002-2008. This equated to a national annual admission rate of about 0.57 per 100,000 people.
The number of admissions for moyamoya disorder roughly doubled between 2002 and 2008. "This may be due to an increased incidence of the disease or increased awareness of the disease, improved imaging modalities, and an increase in the incidence of the diagnosis of moyamoya phenomena as the etiology behind strokes," the researchers write in Neurosurgery.
Ischemic stroke was more common than hemorrhagic stroke in adults (18.8 vs 11.0%) and children (16.4 vs 3.3%). The overall proportion of patients with diagnosed with ischemic stroke rose significantly over the study period, from less than 15% to more than 20%, whereas diagnosis of hemorrhagic stroke remained stable over time.
There were more women than men in the cohort, at 72% versus 28%, and the mean and median age at presentation was 32 years. This unimodal pattern remained when Starke et al divided the patients into Asian and non-Asian races. They note that the established pattern in Asian populations is of two peaks of presentation: the first during childhood and the second in adulthood.
The team adds that moyamoya was previously thought to affect primarily Asians, yet White people accounted for 49% of the current cohort, with Black people accounting for 24%, and Asian and Hispanic races for 11% each. This reflects US demographics, rather than being weighted towards Asians, say Starke et al.
Use of extracranial-to-intracranial bypass increased over the study period, especially among patients with ischemic stroke, yet in-hospital mortality after bypass was low. However, the team says that there "may be a reluctance to operate on more fragile patients" and that surgeons may wait for patients with acute symptoms to stabilize before operating, accounting for the low mortality rate.
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