Narcolepsy/cataplexy. IV: Diagnostic value of daytime nap recordings

Edward O. Bixler, PhD: from the Apollo project and chimpanzees to sleep epidemiology

What an honor to write about Dr. Edward O. Bixler's contributions to the sleep field. In 1967, Dr. Bixler published a case report on a chimpanzee with implanted brain electrodes while working at an Air Force base in New Mexico. A few years later, in 1971, he published on the sleep effects of flurazepam in individuals with insomnia together with Dr. Anthony Kales, data that he had collected when the Sleep Research & Treatment Center (SRTC) was housed at the University of California Los Angeles. Dr. Bixler, a meticulous scientist, learned from Dr. Kales, a devoted clinician, to study "the whole patient, and all aspects of sleep," a legacy that continued when the SRTC moved to Penn State in Hershey. Indeed, Dr. Bixler's tenure at Penn State from 1971 until 2019 kept the science of the SRTC focused on that premise and helped translate scientific evidence into clinical care. He not only contributed early to the pharmacology of sleep and the effects of hypnotics, but he was also a pioneer in "sleep epidemiology." His "Prevalence of sleep disorders in the Los Angeles metropolitan area" study of 1979 was the first rigorous epidemiological study on sleep disturbances. Starting in 1990, he established the Penn State Adult Cohort to estimate the prevalence and natural history of sleep-disordered breathing and other sleep disorders in adults. Inspired by life-course epidemiology, he established in 2001 the Penn State Child Cohort to estimate the same phenomena in children. This Living Legend paper captures and highlights Dr. Bixler's enduring legacy to sleep science.

Chronic fatigue syndrome and fibromyalgia in diagnosed sleep disorders: a further test of the 'unitary' hypothesis

BACKGROUND

Since chronic fatigue syndrome (CFS) and fibromyalgia (FM) often co-exist, some believe they reflect the same process, somatization. Against that hypothesis are data suggesting FM but not CFS was common in patients with sleep-disordered breathing (SDB). The presence of discrete case definitions for CFS and FM allowed us to explore rates of CFS alone, CFS with FM, and FM alone in SDB patients compared to those with sleep complaints that fulfilled criteria for insomnia.

METHODS

Participants were 175 sequential patients with sleep-related symptoms (122 had SDB and 21 had insomnia) and 39 healthy controls. Diagnoses were made by questionnaires, tender point count, and rule out labs; sleepiness was assessed with Epworth Sleepiness Scale and mood with Beck Depression Inventory.

RESULTS

Rates of CFS, FM or CFS + FM were high: 13% in SDB and 48% in insomnia. CFS occurred frequently in SDB and insomnia, but FM occurred frequently only in insomnia. SDB patients with CFS and/or FM had higher daytime sleepiness than those without these disorders.

CONCLUSION

CFS patients should complete Epworth scales, and sleep evaluation should be considered for those with scores ≥ 16 before receiving the diagnosis of CFS; the coexistence of depressed mood in these patients suggests some may be helped by treatment of their depression. That FM was underrepresented in SDB suggests FM and CFS may have different underlying pathophysiological causes.

Differences in nocturnal and daytime sleep between primary and psychiatric hypersomnia: diagnostic and treatment implications

OBJECTIVE

The differential diagnosis of primary (idiopathic) vs. psychiatric hypersomnia is challenging because of the lack of specific clinical or laboratory criteria differentiating these two disorders and the frequent comorbidity of mental disorders in patients with primary hypersomnia. The aim of this study was to assess whether polysomnography aids in the differential diagnosis of these two disorders.

METHODS

After excluding patients taking medication and those with an additional diagnosis of sleep-disordered breathing, we compared the nocturnal and daytime sleep of 82 consecutive patients with a diagnosis of either primary hypersomnia (N = 59) or psychiatric hypersomnia (N = 23) and normal control subjects (N = 50).

RESULTS

During nocturnal sleep, patients with psychiatric hypersomnia showed significantly higher sleep latency, wake time after sleep onset, and total wake time and a significantly lower percentage of sleep time than patients with primary hypersomnia and control subjects (p < .05). In addition, the daytime sleep of patients with psychiatric hypersomnia was significantly higher in terms of sleep latency, total wake time, and percentage of light (stage 1) sleep and lower in terms of percentage of sleep time and stage 2 sleep than in patients with primary hypersomnia and control subjects (p < .05). The daytime sleep of patients with primary hypersomnia as compared with that of control subjects was characterized by lower sleep latency and total wake time and a higher percentage of sleep time (p < .05). Finally, a sleep latency of less than 10 minutes or a sleep time percentage greater than 70% in either of the two daytime naps was associated with a sensitivity of 78.0% and a specificity of 95.7%.

CONCLUSIONS

Our findings indicate that psychiatric hypersomnia is a disorder of hyperarousal, whereas primary hypersomnia is a disorder of hypoarousal. Polysomnographic measures may provide useful information in the differential diagnosis and treatment of these two disorders.

Daytime sleepiness and REM abnormalities in Prader-Willi syndrome: evidence of generalized hypoarousal

The aim of this study was to clarify the nature of the sleep abnormalities (excessive daytime sleepiness [EDS] and rapid eye movement [REM] sleep alterations) in Prader-Willi; Syndrome (PWS). Eight PWS patients, 15 normal, 16 narcoleptic, and 16 obese subjects were recorded in the sleep laboratory, both during daytime and nighttime. A principal-finding was that EDS in PWS was associated with an increased amount and depth of sleep. In PWS patients with EDS, compared to those PWS patients without EDS or the narcoleptic, obese, and normal groups, there were significant decreases in wakefulness and increases in percentage of sleep time (ST) and slow-wave sleep (SWS) both during daytime and nighttime testing. Also, in the adult PWS subjects (n = 6), in contrast to normal narcoleptic subjects, intensity of EDS was correlated with increased nocturnal percentage of ST and SWS and % SWS was positively correlated with % ST (both during daytime and nighttime testing). Another principal finding was that in PWS there is a unique alteration of the distribution of REM sleep in relation to controls. PWS patients with EDS or shortened nocturnal REM latencies showed a significantly increased number of REM periods, and a decreased average REM interval between REM periods compared to PWS patients with nonshortened nocturnal REM latencies or to the three control groups. Our data suggest that EDS and REM abnormalities in PWS are not manifestations of a narcoleptic-type syndrome or consequences of obesity. We propose that generalized 24-hour hypoarousal is the primary mechanism underlying the sleep abnormalities in PWS patients.

Relationship of sleep abnormalities to patient genotypes in Prader-Willi syndrome

To assess whether sleep abnormalities are related to the genetic abnormalities in Prader-Willi Syndrome (PWS), we performed polysomnographic studies (nighttime and daytime) and determined the chromosome 15 genotypes in eight patients with PWS. Four patients demonstrated sleep onset REM periods (SOREM), and five met the objective polysomnographic criteria for severe or moderate excessive daytime sleepiness (EDS). Three of the four patients with SOREM displayed a paternally derived deletion of chromosome 15q11-q13, whereas the fourth exhibited maternal uniparental heterodisomy in this chromosomal region (UPD). Two of the four patients that did not display SOREM carried paternally derived deletions; the remaining two demonstrated UPD. Four of the five patients with EDS displayed paternal deletions, and the fifth exhibited UPD. One of three patients without evidence of EDS demonstrated paternal deletion; the remaining two showed UPD. Although neither EDS nor SOREM was not consistently associated with a specific genetic abnormality, these phenotypes may be more common in patients with paternal deletions than in those UPD. Sleep abnormalities in PWS cannot be explained by a single genetic model.

Narcolepsy-cataplexy and loss of sphincter control

We describe the case of a 34-year-old man who presented intermittent faecal incontinence as a manifestation of cataplexy. The patient's sleep history was positive for the full narcoleptic tetrad (sleep attacks, cataplexy, sleep paralysis and hypnagogic hallucinations) while extensive neuropsychiatric work up was negative for any neurologic or psychiatric illness. Repeat polysomnograms (including a polysomnogram with a full seizure montage) were positive for pathologic sleepiness, but there was no evidence of a seizure disorder. The course of the patient's symptomatology and the favourable response of his symptoms to stimulants and imipramine support the theory that his intermittent loss of sphincter control is part of his narcolepsy-cataplexy.

Delta sleep-inducing peptide in normal humans and in patients with sleep apnea and narcolepsy

We measured morning plasma concentrations of delta sleep-inducing-peptide-like-immunoreactivity (DSIP-LI) in 9 sleep apnea patients, 10 narcolepsy patients, and 11 normal controls. Comparisons between the three groups showed no significant differences, although there was a trend toward association with low levels of DSIP-LI in the narcoleptic group, particularly in patients not using medications. No differences were found in the morning or evening plasma DSIP-LI levels in a second group of 11 normal controls and 8 sleep apneics. Our findings do not appear to support a biological marker role of disease activity for single measures of plasma DSIP in sleep apnea.

Episodic cluster headache and narcolepsy: a case report

A patient who first presented with episodic cluster headache later developed narcolepsy. In spite of REM sleep alterations associated with narcolepsy, the frequency and distribution of pain attacks did not change when narcolepsy occurred and were similar to those seen in cases of episodic cluster without narcolepsy. The lack of influence of narcolepsy on the pattern of cluster pains questions the role of REM sleep states in triggering pain in episodic cluster.