Moyamoya syndrome associated with Down syndrome: outcome after surgical revascularization.

OBJECTIVES: This study was undertaken to describe the clinical, radiologic, and angiographic features of moyamoya syndrome in a surgical series of children and adults with Down syndrome. We wished to define the features of moyamoya syndrome associated with Down syndrome and to determine the results of surgical revascularization among these patients at early and late follow-up times.
METHODS: We reviewed the clinical, radiologic, and angiographic records of all patients with moyamoya syndrome associated with Down syndrome, as a subset of a previously reported, consecutive series of patients who underwent cerebral revascularization surgery with a standardized surgical procedure, pial synangiosis, between January 1, 1985, and June 30, 2004.
RESULTS: Of 181 patients with moyamoya syndrome from the initial series who were treated surgically during the study period, 16 patients had Down syndrome (10 female patients and 6 male patients). The average age at onset was 9.3 years (range: 1-29 years); the average age at the time of surgery was 9.8 years (range: 2-29 years). Although the presenting symptoms were transient ischemic attacks for 10 patients and strokes for 6 patients, computed tomographic and/or MRI scans demonstrated bilateral infarctions for 9 patients and unilateral infarctions for 6, with only 1 patient having no imaging evidence of a previous stroke. No cases presented with intracerebral hemorrhage. Preoperative angiography showed the presence of bilateral moyamoya syndrome changes for all patients, including posterior circulation involvement for 8 patients. Surgical treatment included pial synangiosis for all patients, although 1 patient underwent a superficial temporal artery-middle cerebral artery bypass in the contralateral hemisphere. Surgical complications included symptomatic subdural hematomas requiring evacuation, at 48 days and 54 days postoperatively (2 cases), seizures (2 cases), and strokes within 30 days after surgery, at 1 day and 7 days postoperatively (2 cases). Late clinical and radiologic follow-up data (average: 67.6 months; range: 6-146 months) demonstrated no worsening in neurologic status for any patient except for 1 patient who developed a seizure disorder with associated chronic hypocalcemia; she was totally dependent at the 10-year follow-up evaluation, despite no evidence of new infarction since her surgery. There was no clinical or radiologic evidence of new infarction for any patient in late follow-up evaluations. Postoperative angiography, conducted 1 year after surgery for 11 patients, revealed radiologic evidence of good to excellent cerebral revascularization in 85% of the surgically treated hemispheres. Patients were maintained on lifetime aspirin therapy.
CONCLUSIONS: The clinical, radiologic, and angiographic features of moyamoya syndrome associated with Down syndrome seem comparable to those of primary moyamoya disease. Cerebral revascularization surgery with the pial synangiosis technique seems to confer long-lasting protection against additional strokes in this patient population. The presence of moyamoya syndrome should be considered in the evaluation of patients with Down syndrome who present with transient ischemic attack-like symptoms.