[Clinical features of early-onset narcolepsy]

To investigate the clinical features of early onset narcolepsy.

The clinical data of 105 consecutive patients with narcolepsy, 63 of which with an onset age of 9.7 +/- 3.1 on average and 42 with an onset age of 22.8 +/- 9.3 on average. Interrogation, physical examination, CT, and MRI were carried out. Polysomnography was conducted. Then the data were compared between these 2 groups.

All 105 patients showed daytime sleepiness. The incidence rate of cataplexy was 92% in the early onset group, significantly higher than that of the late onset group (P = 0.023). There were no significant differences in the rates of sleep paralysis, hypnagogic hallucination, and disturbed nocturnal sleep. Multiple sleep latency test showed that the mean sleep latency of the early-onset group was 4.5 +/- 4.0 min, significantly shorter than that of the late onset group (7.0 +/- 5.7 min, P = 0.018); the REM sleep latency of the early onset group was 3.4 +/- 3.2 min, significantly shorter than that of the late onset group (4.8 +/- 2.2 min, P = 0.02). The number of REM sleep of the early onset group was 3.4 +/- 2.0, significantly more than that of the late onset group (2.5 +/- 1.9, P = 0.09). The apnea and hypopnea index of the late onset group was 9.2 +/- 16.5, significantly higher than that of the early onset group (1.9 +/- 6.3, P = 0.009). The 3 cases of narcolepsy with family history were all cases of early onset narcolepsy.

Early onset narcolepsy patients have more severe daytime sleepiness and higher rate of cataplexy. The pathogenesis of early onset narcolepsy may be more closely associated with genetic factors.