Giant Tumefactive Perivascular Spaces: An Unusual Cause of Holmes Tremor.

A 34-year-old man presented with a 2-year history of medically refractory Holmes tremor in the right upper limb. Magnetic resonance imaging revealed a large, nonenhancing, multiseptate cystic lesion of cerebrospinal fluid intensity in the left thalamopeduncular region causing brainstem compression and hydrocephalus. A diagnosis of giant tumefactive perivascular spaces was made after a biopsy ruled out an infectious or neoplastic etiology. Significant clinicoradiologic improvement was noted following a ventriculoperitoneal shunt. Giant tumefactive perivascular spaces should be included as one of the rare differentials of a large, nonenhancing cystic lesion situated along the course of perforator vessels. Treatment options include cerebrospinal fluid diversion with or without cyst fenestration.