To the Editor: Involuntary Emotional Expression Disorder (IEED) is characterized by inappropriate and compulsive laughing and/or crying episodes.¹ A dysfunction of a cortical-limbic-subcortical-thalamic-ponto-cerebellar circuit (CLSTPC) has been hypothesized.²

There is no standard therapy for IEED.³ We first report on a 12-year-old child with IEED treated with aripiprazole, an antipsychotic agent mainly acting as partial agonist on D₂ presynaptic autoreceptors and 5HT_1A receptors, and antagonist on postsynaptic D₂ and 5HT_2A receptors.³

The 12 year-old-boy born at term presented perinatal asphyxia provoking periventricular leucomalacia and spastic tetraparesis. Cognitive development was normal. At 5 years of age, a generalized clonic seizure during sleep occurred. Phenobarbital was started at an unknown dosage and stopped 6 months later because of hyperactivity. Five years later he presented a second seizure during sleep. Levetiracetam 500mg/d was started and continued up to our first observation at 11.6 years of age. No further seizures occurred during this period. Since the age of 9 years, unexplained episodes of compulsive laughing occurred mainly at night. When they occurred (rarely) during daytime the child felt very embarrassed. The child presented spastic tetraparesis, more marked in the lower limbs and a normal cognitive level. A nocturnal video-polysomnography ruled out gelastic seizures. Brain MRI scan displayed periventricular leucomalacia. There was no evidence of hypothalamic hamartoma. During the nocturnal video-polysomnography the child presented several attacks of uncontrolled laughter lasting from 2-3 up to 90 seconds. These occurred at 2-4 minute intervals and were associated with movements to adjust position in bed and head rolling. No paroxysmal epileptic discharges were recorded on the EEG during these episodes. Consciousness was not affected. Involuntary motor phenomena or automatisms were not observed. The child attempted to hide the episodes by laughing quietly. The laughing attacks strongly interfered with the child falling asleep. Levetiracetam was gradually reduced, lamotrigine was slowly titrated up to 100mg/d without beneficial effects. Aripiprazole 1.5mg/d was started with complete disappearance of the episodes for one month. Because of a relapse, the dosage was increased to 2.5mg/d resulting in the dramatic disappearance of episodes. Five months later, the boy’s parents spontaneously stopped aripiprazole and the IEED reappeared. It disappeared again when aripiprazole was reintroduced at the same dosage.

Our 12-year-old patient with IEED was strongly impaired in his social relationships and nocturnal rest. Although IEED has never been reported in patients with periventricular leucomalacia, the WM damage in our patient could have induced a cortical-limbic-subcortical-thalamic-ponto-cerebellar circuit dysfunction. Treatment of IEED is not well established although several drugs have been used (SSRI, TCAs, L-DOPA and DOPA agonists and dextromethorphan).³ Our patient showed a dramatic response to aripiprazole with long-lasting efficacy of 4 years. The compulsive feature of IEED and its multiple neurotransmitters’ modulation induced us to try aripiprazole.⁴ Moreover aripiprazole has been thought to increase the dopamine levels in the hippocampus and prefrontal cortex⁵ and the latter seems to play a major role in emotional expression control.² The relapse of laughing episodes after aripiprazole discontinuation and their disappearance after its reintroduction confirmed its therapeutic effect.

This work was performed at the Epilepsy Center, Department of Neurosciences, Anesthesiological and Psychiatric Sciences, University of Messina, Messina, Italy.

Authors have nothing to disclose