Posterior fossa tumors with pathological laughter.

Of two patients with posterior fossa tumor and pathological laughter, one had extrinsic compression of the brain stem; the other had an intrinsic brain-stem lesion. Surgical removal of the epidermoid from the cerebellopontine angle cured the laughter. The euphoria of multiple sclerosis with paroxysmal laughter and a feeling of joy is to be differentiated from cases in which pathological laughter is a presenting complaint.