Pediatric cerebellar infarction caused by atlantoaxial subluxation--case report.

An 11-year-old girl developed cerebellar infarction presenting as a posterior fossa mass lesion after stretching and flexing her neck. Cerebral angiography demonstrated irregular narrowing of the right vertebral artery at the C2 level and x-rays of the upper cervical spine showed atlantoaxial subluxation with os odontoideum. She underwent surgical decompression with removal of infarcted tissue. The cerebellar infarction probably resulted from occlusion of the vertebral artery, followed by brain swelling due to recanalization.