A standardized test to document cataplexy.

OBJECTIVE/BACKGROUND: Cataplexy is the pathognomonic symptom of narcolepsy type 1 (NT1). Since it is considered difficult to be directly observed or documented by clinicians, its diagnosis relies mainly on history taking. Our study aimed at testing the feasibility of a standardized video recording procedure under emotional stimulation to document cataplexy in the diagnostic work-up of suspected hypersomnia of central origin. PATIENTS/METHODS: Two-hundred-eight consecutive patients underwent the diagnostic work-up and reached the final diagnosis of NT1 (n = 133), idiopathic hypersomnia or narcolepsy type 2 (IH/NT2 group, n = 33), or subjective excessive daytime sleepiness (sEDS group, n = 42). All subjects underwent a standardized video recording procedure while watching funny movies selected according to individual preferences, and a technician blind to clinical features reviewed the recordings to identify hypotonic phenomena that were finally confirmed by patients. RESULTS: The video recording under emotional stimulation captured hypotonic phenomena in 72.2%, 9.1% and 4.8% of NT1, IH/NT2, and sEDS subjects (p < 0.0001), respectively. When tested against CSF hypocretin deficiency, the documentation of a hypotonic episode at the test showed an area under the ROC curve of 0.823 ± 0.033 (p < 0.0001). NT1 patients under anticataplectic medications showed less frequently hypotonic episodes than untreated ones (48.0% vs 77.8%, p = 0.003). CONCLUSIONS: A standardized video recording procedure under emotional stimulation can help in the characterization of suspected hypersomnia of central origin. Further multi-center studies are warranted to extend the present findings and integrate a shared procedure for the laboratory work-up of narcolepsy.

Decreased sleep stage transition pattern complexity in narcolepsy type 1.

OBJECTIVE: To analyze the complexity of the nocturnal sleep stage sequence in central disorders of hypersomnolence (CDH), with the hypothesis that narcolepsy type 1 (NT1) might exhibit distinctive sleep stage sequence organization and complexity. METHODS: Seventy-nine NT1 patients, 22 narcolepsy type 2 (NT2), 22 idiopathic hypersomnia (IH), and 52 patients with subjective hypersomnolence (sHS) were recruited and their nocturnal sleep was polysomnographically recorded and scored. Group between-stage transition probability matrices were obtained and compared. RESULTS: Patients with NT1 differed significantly from all the other patient groups, the latter, in turn, were not different between each other. The individual probability of the R-to-N2 transition was found to be the parameter showing the difference of highest significance between the groups (lowest in NT1) and classified patients with or without NT1 with an accuracy of 78.9% (sensitivity 78.5% and specificity 79.2%), by applying a cut-off value of 0.15. CONCLUSIONS: The main result of this study is that the structure of the sleep stage transition pattern of hypocretin-deficient NT1 patients is significantly different from that of other forms of CDH and sHS, with normal hypocretin levels. SIGNIFICANCE: The lower probability of R-to-N2 transition occurrence in NT1 appears to be a reliable polysomnographic feature with potential application at the individual level, for supportive diagnostic purposes.

Nocturnal Sleep Dynamics Identify Narcolepsy Type 1.

STUDY OBJECTIVES: To evaluate the reliability of nocturnal sleep dynamics in the differential diagnosis of central disorders of hypersomnolence. DESIGN: Cross-sectional. SETTING: Sleep laboratory. PATIENTS: One hundred seventy-five patients with hypocretin-deficient narcolepsy type 1 (NT1, n = 79), narcolepsy type 2 (NT2, n = 22), idiopathic hypersomnia (IH, n = 22), and "subjective" hypersomnolence (sHS, n = 52). INTERVENTIONS: None. METHODS: Polysomnographic (PSG) work-up included 48 h of continuous PSG recording. From nocturnal PSG conventional sleep macrostructure, occurrence of sleep onset rapid eye movement period (SOREMP), sleep stages distribution, and sleep stage transitions were calculated. Patient groups were compared, and receiver operating characteristic (ROC) curve analysis was used to test the diagnostic utility of nocturnal PSG data to identify NT1. RESULTS: Sleep macrostructure was substantially stable in the 2 nights of each diagnostic group. NT1 and NT2 patients had lower latency to rapid eye movement (REM) sleep, and NT1 patients showed the highest number of awakenings, sleep stage transitions, and more time spent in N1 sleep, as well as most SOREMPs at daytime PSG and at multiple sleep latency test (MSLT) than all other groups. ROC curve analysis showed that nocturnal SOREMP (area under the curve of 0.724 ± 0.041, P < 0.0001), percent of total sleep time spent in N1 (0.896 ± 0.023, P < 0.0001), and the wakefulness-sleep transition index (0.796 ± 0.034, P < 0.0001) had a good sensitivity and specificity profile to identify NT1 sleep, especially when used in combination (0.903 ± 0.023, P < 0.0001), similarly to SOREMP number at continuous daytime PSG (0.899 ± 0.026, P < 0.0001) and at MSLT (0.956 ± 0.015, P < 0.0001). CONCLUSIONS: Sleep macrostructure (i.e. SOREMP, N1 timing) including stage transitions reliably identifies hypocretin-deficient narcolepsy type 1 among central disorders of hypersomnolence.