Intracranial dermoid cyst rupture with midbrain and thalamic infarction.

A 39-year-old man developed dizziness and diplopia. Examination showed medial gaze palsy of the right eye. He had no headache, vertical gaze palsy, or skew deviation. A CSF examination was not performed. MRI (figure) showed cystic mass and acute infarction. After 7 days heparization, the mass was removed by surgery and pathology confirmed the dermoid cyst. After operation, the neurologic abnormality disappeared. Epidermoid cyst, arachnoid cyst, and cystic craniopharyngioma are differential diagnoses. Although intracranial dermoid cysts are rare benign tumors,1 surgery is the only treatment and rupture of a cyst can lead to cerebral vasospasm or vasculitis.2