Klein Levin Syndrome is a steroid-responsive, non-N-methyl-D-aspartate receptor-mediated encephalitis

Abstract

OBJECTIVE: Klein Levin Syndrome is a rare disorder with periodic hypersomnia, cognitive and behavioural disturbance. It is postulated that it is triggered by a viral illness or post-infectious autoimmune encephalitis. With an increasing awareness of autoimmune encephalitis in the past 10years, especially N-methyl-D-aspartate receptor (NMDAR) mediated encephalitis, testing for the presence of NMDAR antibodies in patients with Klein Levin Syndrome should give us more understanding about the relationship between the two disease entities. DESIGN: CASE REPORT. A 15year-old boy with Klein Levin Syndrome presented with episodic attacks of repetitive excessive masturbation, hypersomnia, compulsive water drinking, and fluctuation in blood pressure. He had enjoyed good health in the past and was completely normal in between the attacks. The disease onset was related to a recent upper respiratory tract infection. Extensive work up was unrevealing, excluding microbiological, metabolic and autoimmune causes. Electroencephalogram showed nonspecific frontal intermittent rhythmic delta activities. Magnetic resonance imaging of the brain was normal. Serum and cerebrospinal fluid were sent for NMDAR antibodies during an episodic attack and were negative. Intravenous pulsed methylprednisolone (Pfizer, Puurs, Belgium) was given for 3days, followed by a course of oral prednisolone (APT Pharma, Hong Kong). The boy went into remission afterwards. However, the neuropsychiatric symptoms recurred upon tapering of the oral steroid. Currently, the condition is well controlled with lithium (Norgine, Harefield, UK). CONCLUSION: We support the hypothesis that Klein Levin Syndrome is an autoimmune encephalitis that is steroid-responsive. However the underlying mechanism is not NMDAR antibody mediated. Further study on a larger group of patients would help to elucidate the underlying aetiology.