Clinical and polysomnographic characteristics in 20 North Indian patients with narcolepsy: A seven-year experience from a neurology service sleep clinic

Abstract

Narcolepsy is not an uncommon sleep disorder in the West. There is, however, only one reported case in literature from India. In this study, we report characteristics of patients with narcolepsy over a seven-year period. Details of all patients with narcolepsy seen at a Sleep Disorders Clinic over seven years were analyzed. Diagnosis had been established by clinical history and two or more Sleep Onset Rapid Eye Movement Periods (SOREMPs) on Multiple Sleep Latency Test (MSLT) following an overnight Polysomnography (PSG), using the International Classification of Sleep Disorders - 2 (ICSD-2) criteria. Patients fulfilling the criteria, but suffering from other disorders were excluded. Data of 20 patients were analyzed and 4 patients were excluded, as they had other associated conditions. Mean age at onset of symptoms was 25±10 years; 12 (60%) patients had narcolepsy with cataplexy, 4 (20%) patients presented with all cardinal symptoms of narcolepsy, 8 (40%) with 3 symptoms, while 8 (40%) presented with 2 symptoms. History of Excessive Day-Time Sleepiness (EDS) was present in all patients. Three patients reported accidents due to sleep attacks, one being life-threatening. On PSG, mean sleep efficiency was 79.4±12.40%. Mean sleep latency during MSLT was 1.30 minute (range: 0.30-2.30 minute) and mean REM latency was 2.58±0.64 minute. Narcolepsy with and without cataplexy is infrequently seen in the North Indian population; however, clinical and polysomnographic features are similar to those observed in Western and other Asian populations.