[Kleine-Levin syndrome: differential diagnosis in recurrent encephalitic syndromes in adolescence]

The Kleine-Levin syndrome is a rare disease of unknown origin characterized by recurrent and self-limited episodes of hypersomnia that are also accompanied by a cognitive and behavioral dysfunction. Patients present normal sleeping and behavior patterns between episodes.

We present three patients who are 14 years old: two boys and one girl. They started having the episodes after a predisposing factor (vaccine, influenza B and menstruation). During the episode they presented hypersomnolence and while wakefulness they were bradipsychic, in motor restlessness and with emotional liability. They also presented a tendency towards crying and claimed the presence of relatives constantly. The episodes lasted between 10 and 15 days and they appeared monthly, being asymptomatic between episodes. All three patients were attended initially by pediatricians, diagnosed and treated as autoimmune encephalitis. Only one of our cases had the three typical symptoms of hypersomnia, hyperfagia and hypersexuality. However, none of the three had been asked initially and the family only referred to it after the directed anamnesis.

The Kleine-Levin syndrome presents neurologic symptoms initially more frequently than psychiatric ones. Hypersomnia and behavioural disturbances during wakefulness, bradypsychia, apatheia and emotional liability make us suspect that it could be an encephalitis process. We should be aware of this entity if we face a patient with recurrent encephalitis of unknown origin.