Central Disorders of Hypersomnolence in Children and Adults: A Comparative Study from South India

Narcolepsy and idiopathic hypersomnolence (IHS) are rare disorders. In Western populations, the reported prevalence of narcolepsy is 0.02%-0.05%. In Indian subcontinent, there are few reports on narcolepsy and none on IHS so far. Here, we compared the clinical and polysomnographic profile of narcolepsy/IHS among the pediatric and adult groups.

The patients presenting with excessive daytime sleepiness (EDS) attending sleep clinic from January 2010 to December 2015 were included. Patients were diagnosed with narcolepsy type 1 (NT1), narcolepsy type 2 (NT2), and IHS based on the International Classification for Sleep Disorders criteria. Patients with secondary causes of EDS were excluded from the study.

A total of 56 patients were included in the study (29 males and 27 females). The mean age of symptom onset was 29 years (males - 34 years and females - 24 years). Twelve (21%) patients had NT1, five (9%) patients had NT2, whereas 38 (68%) patients had IHS compared to narcolepsy, the IHS had an older mean age at presentation. The average time from symptom onset to diagnosis was 71 months. Classical tetrad of narcolepsy was rarely found in pediatric cohort, but they had more behavioral problems and weight gain. Pediatric cohort of IHS also reported behavioral problems. The mean sleep-onset latency was 3.1 min, while the mean rapid eye movement latency was 7.2 min.

The pediatric narcolepsy patients tend to have less classical symptoms and more behavioral/eating problems as compared to adult cohort. There is significant delay in diagnosing narcolepsy, indicating the need to increase awareness among the physicians about this rare treatable disorder.