Outcome of Therapies for Moyamoya Disease in Children

Nowadays, revascularization surgery is indicated for virtually all children with Moyamoya Disease except for children with widespread cerebral infarcts or serious medical illnesses. The progressive nature of Moyamoya Disease in pediatric period and the facts that about 90% of pediatric cases are asymptomatic or in improved state after surgery of any kind, and that the main factor of long-term poor prognosis is cerebral infarction suggest the importance of early diagnosis and surgical treatment of Moyamoya Disease in childhood.

• Hemodynamic and Neurological Outcome: The improvement of hemodynamics is reported in from 83% to 96% of cases. Although the cerebral hemodynamics are more improved in ‘direct’ revascularization or ‘combination of direct and indirect surgery’ cases than in ‘indirect surgery only’ cases, the difference is not significant and the functional state is also not different in children with Moyamoya Disease (13). Contrary to the pediatric patients, direct revascularization with or without indirect surgery is the main treatment for adults because of their poor response to indirect revascularization.
• Functional Outcome: Long term outcome of children with Moyamoya Disease largely depends on the presence or extent of cerebral infarction. In a review of large number of pediatric cases (1,156 cases) 69% of the patients are independent and 23% partly dependent (13).
• Overall outcomes: There is abundant evidence that surgical revascularization improves a wide range of outcome metrics in children with moyamoya.  Radiographically, revascularization reverses white matter changes, improves measures of cerebral oxygenation and increases cerebral blood flow, while stabilizing stroke burden – despite progressive arteriopathy (5,18,31,35,47,51,63).  Clinically, surgery decreases ischemic symptoms, headache and risk of hemorrhage and markedly reduces stroke rates (without surgery, stroke risk is 32% at 1 year and 66-90% at 5 years; after surgery, stroke risk drops to <5% for most populations at both 1 and 5 year time points), while concomitantly improving functional and cognitive outcomes (1,5,11,18,24,37,39,40,47).
• Role of high-volume centers: It is increasingly clear that one of the most important predictors of surgical outcome is whether the child is treated at a high-volume center with a dedicated pediatric cerebrovascular team (4).  Recent data from national database analysis reveals that high-volume centers (averaging >30 procedures annually) had shorter lengths of stay (32%), lower costs (57%), 8-fold more likely discharge to home (versus rehabilitation) and a 15-fold lower rate of death (58).  These data support regionalization of care with centers of excellence for subspecialized care.