Tentorial meningioma associated with pathological laughter--case report.

A 33-year-old male presented with involuntary and inappropriate laughter. Neuroimaging revealed a meningioma ventrolateral to the pens and midbrain, attached to the medial middle tentorium on the left side. The pathological laughter ceased immediately after subtotal removal of the tumor, Pathological laughter may be an early focal sign of a mass compressing ventrolateral brainstem.