Central Disorders of Hypersomnolence.

OBJECTIVE: The goals of this article are to describe the clinical approach to and management of patients with central disorders of hypersomnolence, and to understand and differentiate available diagnostic tools. LATEST DEVELOPMENTS: Updated clinical practice guidelines for the treatment of central disorders of hypersomnolence and narcolepsy specifically highlight new treatment options. Approval for a lower-sodium oxybate formulation that contains 92% less sodium than the standard sodium oxybate for the treatment of narcolepsy and idiopathic hypersomnia adds to the number of medications available for these disorders, allowing for a more tailored management of symptoms. ESSENTIAL POINTS: Central disorders of hypersomnolence are characterized by excessive daytime sleepiness that impacts daily functions. These disorders can be differentiated by obtaining a detailed clinical sleep history and by a thoughtful interpretation of sleep diagnostic testing. Tailoring treatment approaches to meet the needs of individuals and accounting for medical and psychiatric comorbidities may improve quality of life.

Narcolepsy and Idiopathic Hypersomnia.

Narcolepsy types 1 and 2 and idiopathic hypersomnia are primary Central Nervous System (CNS) disorders of hypersomnolence characterized by profound daytime sleepiness and/or excessive sleep need. Onset of symptoms begins typically in childhood or adolescence, and children can have unique presentations compared with adults. Narcolepsy type 1 is likely caused by immune-mediated loss of orexin (hypocretin) neurons in the hypothalamus; however, the causes of narcolepsy type 2 and idiopathic hypersomnia are unknown. Existing treatments improve daytime sleepiness and cataplexy but there is no cure for these disorders.

A protocol for mitigating safety events in a sleep laboratory.

STUDY OBJECTIVES: Polysomnography is a common outpatient procedure and the rate of adverse events is considered low. Due to the emergence and use of home sleep apnea testing, the patient population presenting for in-laboratory testing may have greater medical complexity, suggesting greater risk for in-laboratory adverse events. We believe that there is a greater need for standardized protocols to triage medically vulnerable populations and for formalized training of sleep technicians to respond to safety events. METHODS: The sleep laboratories affiliated with the Beth Israel Deaconess Medical Center system developed a referral triage protocol for patients undergoing polysomnography and a training protocol for sleep technicians with a formalized response to medical incidents. Safety events occurring from January 2016 to January 2020 were documented and patient demographics, referral characteristics, event characteristics, and outcomes were analyzed. RESULTS: Sixty-five safety events occurred over this period, with a rate of 1:147 studies. The most common events were chest pain (20/65, 31%), shortness of breath (13/65, 20%), and vital sign abnormalities (12/65, 18%). Patients experiencing events were 49% (32/65) female, with a median age of 57 years (range, 19-91 years); 60 of 65 (92%) had documented medical comorbidities, with a median of 3 documented medical or psychiatric comorbidities (range, 0-9). With the formalized response protocol, the time from incident identification to activation of the appropriate response was a median of 3 minutes (range, 0-47 minutes). CONCLUSIONS: The incidence of in-laboratory safety events may be greater than previously described due to the widespread use of home sleep apnea testing. Implementation of formalized response protocols and sleep technician training may be necessary to meet the needs of an increasingly medically complex population.

Sleep Disturbances in Patients with Autoimmune Encephalitis.

PURPOSE OF REVIEW: To review sleep complaints reported in patients with autoimmune encephalitis, explore the relationship between sleep disturbances and subtypes of autoimmune encephalitis, and leverage knowledge concerning antibody-antigen specificity to inform the receptors, structures, and disseminated neural networks that contribute to sleep function in health and disease. RECENT FINDINGS: Autoimmune encephalitis is an inflammatory brain disorder characterized by the subacute onset of psychiatric symptoms, cognitive impairment, and focal neurologic deficits or seizures. Sleep disturbances are detected in a majority of patients systematically screened for sleep complaints, may be the presenting symptom in patients with autoimmune encephalitis, and may compromise recovery in patients with autoimmune encephalitis. Early recognition of specific sleep disturbances in patients with subacute changes in behavior or cognition may support the diagnosis of autoimmune encephalitis. Similarly, recognition and treatment of sleep dysfunction in patients with known autoimmune encephalitis may speed recovery and improve long-term outcomes.

Increased Cerebrospinal Fluid Amyloid-ß During Sleep Deprivation in Healthy Middle-Aged Adults Is Not Due to Stress or Circadian Disruption.

BACKGROUND: Concentrations of soluble amyloid-ß (Aß) oscillate with the sleep-wake cycle in the interstitial fluid of mice and cerebrospinal fluid (CSF) of humans. Further, the concentration of Aß in CSF increases during sleep deprivation. Stress and disruption of the circadian clock are additional mechanisms hypothesized to increase CSF Aß levels. Cortisol is a marker for stress and has an endogenous circadian rhythm. Other factors such as glucose and lactate have been associated with changes in sleep-wake activity and/or Aß. OBJECTIVE: In this exploratory study, we used samples collected in a previous study to examine how sleep deprivation affects Aß, cortisol, lactate, and glucose in plasma and CSF from healthy middle-aged adults (N = 11). METHODS: Eleven cognitively normal participants without evidence of sleep disturbance were randomized to sleep deprivation or normal sleep control. All participants were invited to repeat the study. Cortisol, lactate, glucose, and Aß were measured in 2-h intervals over a 36-h period in both plasma and CSF. All concentrations were normalized to the mean prior to calculating mesor, amplitude, acrophase, and other parameters. RESULTS: One night of sleep deprivation increases the overnight concentration of Aß in CSF approximately 10%, but does not significantly affect cortisol, lactate, or glucose concentrations in plasma or CSF between the sleep-deprived and control conditions. CONCLUSION: These data suggest that sleep deprivation-related changes in CSF Aß are not mediated by stress or circadian disruption as measured by cortisol.

Sleep disturbances are common in patients with autoimmune encephalitis.

OBJECTIVES: Autoimmune encephalitis (AE) is increasingly recognized as an important cause of subacute cognitive decline, seizures, and encephalopathy, with an ever-broadening clinical phenotype. Sleep disturbances are reported in AE patients, including rapid eye movement sleep behavior disorder, hypersomnia, fragmented sleep, and sleep-disordered breathing; however, the prevalence of sleep disturbances and contributions to outcomes in AE patients remain unknown. There is a need to determine the prevalence of sleep disturbances in AE patients, and to clarify the relationship between specific autoantibodies and disruptions in sleep. METHODS: Clinical history, results of serum and cerebrospinal fluid testing, electroencephalography, and neuroimaging were reviewed from 26 AE patients diagnosed and managed at our tertiary care hospital. Polysomnography was performed in patients with clinical indications, yielding data from 12 patients. RESULTS: The median age of AE patients was 53 years (range 18-83). Autoantibodies against intracellular antigens (including Ma and Hu autoantibodies) were identified in 6/26 (23%) patients, while autoantibodies against cell-surface neuronal antigens (including NMDAR and LGI1) were identified in 20/26 (77%) patients. New sleep complaints were reported by 19/26 (73%) AE patients, including gasping or snoring (9/19, 47%), dream enactment behavior (6/19, 32%), insomnia (5/19, 29%), hypersomnia (4/19, 21%), other parasomnias (4/19, 21%), and dream-wake confusional states (2/19, 11%). Dream enactment behaviors were particularly common in AE associated with LGI1 autoantibodies, reported in 4/7 (57%) patients. Polysomnography showed reduced total sleep time, stage 3 and rapid eye movement sleep, and prominent sleep fragmentation. CONCLUSION: Sleep disturbances are common in AE, warranting active surveillance in affected patients. Improved identification and treatment of sleep disorders may reduce morbidity associated with AE and improve long-term outcomes.

Chemotherapy-associated Posterior Reversible Encephalopathy Syndrome: A Case Report and Review of the Literature.

INTRODUCTION: There are increasing reports of posterior reversible encephalopathy syndrome (PRES) associated with the use of chemotherapeutic agents. Recognition of PRES is crucial given its reversibility with appropriate supportive management. We report a patient presenting with PRES after treatment with Rituximab, Cyclophosphamide, Hydroxydaunorubicin/Adriamycin, Oncovin/Vincristine, Prednisone (R-CHOP) and intrathecal methotrexate. We also perform a systematic review of the literature on chemotherapy-associated PRES. CASE REPORT: A 72-year-old man with recently diagnosed diffuse large B-cell lymphoma became unresponsive 4 days after initiation of R-CHOP and intrathecal methotrexate. Brain magnetic resonance imaging showed interval development of occipital and temporal fluid attenuation inversion recovery hyperintensities consistent with PRES. The patient's blood pressure was aggressively controlled and he received 5 days of high-dose methylprednisone. He subsequently regained consciousness and his mental status gradually improved. Repeat magnetic resonance imaging showed interval resolution of the bilateral fluid attenuation inversion recovery hyperintensities. REVIEW SUMMARY: We performed a systematic review of the literature and included a total of 70 unique cases involving chemotherapy-associated PRES. Platinum-containing drugs, Cyclophosphamide, Hydroxydaunorubicin/Adriamycin, Oncovin/Vincristine, Prednisone/R-CHOP regimens, and gemcitabine were the agents most commonly used in patients who developed suspected chemo-associated PRES. Median onset of symptoms occurred 8 days after chemotherapy. Hypertension was the most commonly reported risk factor associated with the development of chemotherapy-associated PRES. In most cases, PRES improved with supportive management alone within 2 weeks. CONCLUSIONS: Chemotherapy-associated PRES is an increasingly encountered syndrome. Both neurologists and non-neurologists should be familiar with the most commonly implicated agents, symptoms, risk factors, and clinical course of chemotherapy-associated PRES, given its favorable prognosis with appropriate management.

Changes in estrogen receptor signaling alters the timekeeping system in male mice.

Circadian rhythms are modulated by steroid hormones; however, the mechanisms of this action are not fully understood, particularly in males. In females estradiol regulates activity level, pattern of expression, and free running period (tau). We tested the hypothesis that activity level and distribution in male mice includes both classical and "non-classical" actions of estrogens at the estrogen receptor subtype 1 (ESR1). We used transgenic mice with mutations in their estrogen response pathways: ESR1 knock-out (ERKO) mice lack the ability to respond to estrogens via ESR1. "Non-classical" estrogen receptor knock-in (NERKI) mice have an inserted ESR1 receptor with a mutation in the estrogen-response-element binding domain, allowing activation via non-genomic and second messenger pathways. Gonadectomized male NERKI, ERKO, and wildtype (WT) littermates were given oil, or low or high dose estradiol and daily activity parameters were quantified. Estradiol shortened the ratio of activity in the light relative to dark (LD ratio), shortened tau, advanced the time of activity onset, and altered responsiveness to light cues administered in the late subjective night, suggesting modulation by an ESR1-independent mechanism. Estradiol treatment in NERKI but not WT males altered the timing of activity onset, LD ratio, and the behavioral response to light cues. These results may represent disruptions in the balance of genomic/nongenomic or ESR1/ESR2 signaling pathways. We also found a significant genotype effect on total activity, LD ratio, tau, and activity duration. These data provide new information about the role of ESR1-dependent and independent signaling pathways on the timekeeping system in male mice.

Estrogen receptor 1 modulates circadian rhythms in adult female mice.

Estradiol influences the level and distribution of daily activity, the duration of the free-running period, and the behavioral phase response to light pulses. However, the mechanisms by which estradiol regulates daily and circadian rhythms are not fully understood. We tested the hypothesis that estrogens modulate daily activity patterns via both classical and "non-classical" actions at the estrogen receptor subtype 1 (ESR1). We used female transgenic mice with mutations in their estrogen response pathways; ESR1 knock-out (ERKO) mice and "non-classical" estrogen receptor knock-in (NERKI) mice. NERKI mice have an ESR1 receptor with a mutation in the estrogen-response-element binding domain, allowing only actions via "non-classical" genomic and second messenger pathways. Ovariectomized female NERKI, ERKO, and wildtype (WT) mice were given a subcutaneous capsule with low- or high-dose estradiol and compared with counterparts with no hormone replacement. We measured wheel-running activity in a light:dark cycle and constant darkness, and the behavioral phase response to light pulses given at different points during the subjective day and night. Estradiol increased average daily wheel-running, consolidated activity to the dark phase, and shortened the endogenous period in WT, but not NERKI and ERKO mice. The timing of activity onset during entrainment was advanced in all estradiol-treated animals regardless of genotype suggesting an ESR1-independent mechanism. We propose that estradiol modifies period, activity level, and distribution of activity via classical actions of ESR1 whereas an ESR1 independent mechanism regulates the phase of rhythms.

Photic phase-response curve in 2 strains of mice with impaired responsiveness to estrogens.

Steroid hormones including estrogens modulate the expression of daily activity and circadian rhythms, including free-running period, phase angle of activity onset, and response to light. The mechanisms underlying these effects, however, are not fully understood. We tested the hypothesis that estrogen signaling is required for photic responsiveness of the circadian timing system. We used estrogen receptor subtype 1 (ESR1) knock-out mice (ERKO) and nonclassic estrogen receptor knock-in mice (NERKI). ERKO animals are unable to respond to estrogen at ESR1, and NERKI animals lack the ability to respond to estrogens via estrogen response element-mediated transcription but still respond via nonclassical mechanisms. We analyzed behavioral shifts in activity onset in response to 1-h light pulses given across the subjective 24-h day in gonadally intact male and female NERKI, ERKO, and wild-type (WT) littermates. We also examined Fos protein expression in the suprachiasmatic nucleus, the site of the master circadian pacemaker, at 2 times of day. We found a significant effect of genotype on phase shifts in response to light pulses given in the subjective night. Female WT mice had a significantly larger phase response than ERKO females during the early subjective night (phase shift of 98 min and 58 min, respectively; p < 0.05). NERKI females were intermediate to WT and ERKO females, suggesting a contribution of nonclassical estrogen signaling on circadian timekeeping functions. This genotype effect is not observed in males; they did not have a difference in phase shifts following a light pulse at any time point. WT males, however, shifted an average of 47 min less than did females at zeitgeber time (ZT) 16 (ZT 0 lights-on and ZT 12 lights-off). These data indicate that estrogens modify the response of the circadian timekeeping system to light via classical and nonclassical signaling pathways.