Pathological laughter: Common vs, unusual aetiology and presentation

Pathological laughter and crying is a well known clinical phenomenon which in most cases appears in association with diverse neurological and psychiatric symptoms and signs. It is not a disturbance of affectivity but rather of the motor concomitant of affective expression. Its main clinical characteristics are: absence of voluntary control and absence of the corresponding change in mood. It is not accompanied by the emotional lability of the organic brain syndromes, it does not present the inappropriate jocularity of the patients with frontal lobe disturbance, it is not due to the intoxicating effect of alcohol or addictive drugs and there are no typical symptoms of manic syndromes (such as grandiose self-esteem, flight of ideas, hyperactivity, etc.). In this paper three cases of pathological laughter are presented, two of these associated with organic brain conditions. The discussion will deal in particular with aetiological considerations and psychopatholoy of the third case which was unusual because it was a monosymptomatic condition and seemed to be the expression of a posttraumatic stress disorder.