Late postirradiation occlusive vasculopathy in childhood medulloblastoma

The authors report two cases of ischemic stroke secondary to occlusive vasculopathy two decades after radiation therapy (RT) for medulloblastoma. Both patients underwent posterior fossa medulloblastoma partial resection, followed by craniospinal RT in which a cobalt 60 source was used; 40 Gy were given to the whole brain plus a 15-Gy boost to the posterior fossa. Both patients received multiagent chemotherapy, immediately following radiation therapy in the first case and after repeated craniotomy for recurrence 13 years after radiation in the second case. They experienced multiple sequelae from radiation and chemotherapy, including growth retardation and psychomotor delay. However, 20 years after treatment, they remained tumor free and able to work, until they presented with focal neurological deficits and seizures. Computerized tomography and magnetic resonance imaging of the brain in both cases showed no tumor recurrence, but did demonstrate ischemia in a posterior cerebral artery distribution. Cerebral angiography revealed multiple mid- sized arterial wall irregularities as well as focal stenoses consistent with a postirradiation vasculopathy. The pathophysiological mechanisms, radiological appearance, and incidence of this syndrome are reviewed from the literature.