Vascular malformations of the posterior fossa. Clinical and radiologic features.

Thirty-one patients with vascular malformations of the posterior fossa were studied to determine their clinical presentation and radiologic diagnosis. The most common clinical presentations were acute hemorrhage (68%, 21/31) and progressive or fluctuating focal neurologic deficits resembling those found in other pathologic processes (19%, 6/31). Trigeminal neuralgia and hemifacial spasm occurred in these patients, but they were rarely initial presenting symptoms. Computed tomography, after infusion of contrast medium, was abnormal in 95% (20/21) of the patients. Angiography established or confirmed the diagnosis in most of the patients; however, a negative angiogram, especially in cases with recent hemorrhage, does not exclude the diagnosis.