Clinical reasoning: Multiple cranial neuropathies in a young man.

A 19-year-old man with no significant medical history noted 3 weeks of right facial numbness and slurred speech. On examination, he had decreased sensation in the right middle and lower trigeminal nerve distributions, right tongue deviation, and bilateral facial weakness. A lumbar puncture yielded CSF with a lymphocytic predominant pleocytosis (50 leukocytes/mm3, 95% lymphocytes), elevated protein (260 mg/dL), and normal glucose (49 mg/dL), without other evidence of inflammation or infection, while serum studies were normal. Brain MRI with gadolinium demonstrated a subcentimeter left frontal subcortical white matter lesion on fluid-attenuated inversion recovery images and a nonenhancing pineal cyst.