"Pressure to laugh": an unusual epileptic symptom associated with small hypothalamic hamartomas.

Gelastic seizures are the hallmark of the epilepsy syndrome associated with hypothalamic hamartomas. Patients typically develop cognitive deterioration and refractory seizures. The authors describe three patients with small hypothalamic hamartomas without these features and thus identify a mild end to the clinical spectrum. All had the unusual symptom of "pressure to laugh," often without actual laughter. This symptom could be dismissed as psychogenic but should be recognized as a clue to the presence of this unusual lesion.