Different fates of excessive daytime sleepiness: survival analysis for remission

BACKGROUND

Excessive daytime sleepiness (EDS) is a symptom frequently presented in sleep clinics. Only a paucity of data has addressed clinical courses of sleep disorders with EDS. Therefore, we sought to compare clinical outcomes of patients presenting EDS.

METHODS

A retrospective observational study was performed in the setting of sleep laboratory and outpatient department in a university hospital. One hundred and eight patients who presented EDS underwent polysomnography and multiple sleep latency test. Each patient was diagnosed as one of the following four categories: (1) narcolepsy with cataplexy (N + C; n = 29); (2) narcolepsy without cataplexy (N - C; n = 22); (3) idiopathic hypersomnia (IH; n = 24); and (4) subjective hypersomnolence (SH; n = 33) with mean sleep latency >8 min. Remission of EDS and treatment response were determined based on clinical evaluation. Kaplan-Meier survival analysis was performed.

RESULTS

Remission rates were significantly different (P < 0.001, overall log-rank test) among four groups except those between N - C and IH (P = 0.489). While N + C showed no remission, predicted remission rates of N - C and IH group were 44.6% at 5 years and 32.5% at 5.5 years after diagnosis. The predicted remission rate of SH group was 71.7% at 3 years after diagnosis.

CONCLUSIONS

The similarity of clinical courses between N - C and IH suggests that N - C may be more related to IH compared to N + C. Considering different clinical courses among EDS patients, thorough evaluation of EDS should be warranted before starting treatment.

Prevalence of narcolepsy-cataplexy in Korean adolescents

BACKGROUND

Narcolepsy typically begins between adolescence and early adulthood causing severe neuropsychiatric impairments, but few prevalence studies are available on adolescent narcoleptics. In the present study, we investigated the prevalence of narcolepsy-cataplexy in adolescents.

METHODS

In total 20,407 students, aged 14-19 years, participated in this study. Ullanlinna Narcolepsy Scale (UNS) was applied to all subjects and those with a UNS score of > or =14 were contacted by phone for semi-structured interview. Subjects then suspected of having narcolepsy participated in a laboratory investigation, which included polysomnography and HLA typing, or were interviewed in detail by telephone.

RESULTS

Three subjects were finally diagnosed as narcolepsy with cataplexy and seven subjects might be diagnosed as narcolepsy without cataplexy. Among three narcoleptics with cataplexy, two subjects were HLA-DQB1*0602 and DRB1*1501 positive, but one subject had no test of HLA typing. The prevalence of narcolepsy with cataplexy in Korean adolescence was thus determined to be 0.015% (95% confidence interval = 0.0-0.0313%).

CONCLUSION

This epidemiologic study is the first of its type on adolescent narcolepsy to use the International Classification of Sleep Disorders, 2nd edition (ICSD-2) diagnostic criteria. Considering those cases with an onset after adolescence were not included, the prevalence of narcolepsy with cataplexy determined in the present study is comparable with that of other studies in adults.

Degree of arousal is most correlated with blood pressure reactivity during sleep in obstructive sleep apnea

We investigated blood pressure (BP) reactivity of obstructive sleep apnea (OSA) during rapid eye movement (REM) sleep and non-rapid eye movement (NREM) sleep. The influences on BP reactivity of degree of arousal, the lowest O2 saturation (SaO2), and respiratory disturbance (RD) duration were compared. Ten normotensive or borderline hypertensive patients with OSA were studied with one-night polysomnography including non-invasive beat-to-beat BP monitoring (Finapres). We compared baseline BP, pre-apneic BP, and post-apneic BP during both REM and NREM sleep. Also, relationships between delta BP (post-apneic BP minus pre-apneic BP) and degree of arousal, the lowest SaO2, and RD duration were examined. During both REM and NREM sleep, pre-apneic BP was elevated compared with baseline BP. Post-apneic BP elevation was noted compared with pre-apneic BP. The degree of arousal was more significantly correlated with delta BP than the lowest SaO2. RD duration was hardly correlated with delta BP. Pre-apneic BP elevation seems to result from cumulation of sympathetic activation and sympathetic nervous system resetting. The correlation between delta BP and degree of arousal suggests that sympathetic activation causing post-apneic BP elevation may result mainly from an arousal response regardless of hypoxia.