TCM syndrome differentiation and treatment of narcolepsy based on neurobiological mechanism: A review.

Narcolepsy is a relatively rare brain disorder caused by the selective loss of orexin neurons. Narcolepsy is divided into Narcolepsy Type 1 (NT1) and Narcolepsis Type 2 (NT2). The pathogenesis of NT1 has been well established due to the severe loss of orexin neurons, while NT2 is still poorly understood, and little is known about its underlying neurobiological mechanisms. human leukocyte antigen alleles have been found to strongly influence the development of narcolepsy, with more than 90% of NT1 patients carrying the human leukocyte antigen II allele DQB1*06:02. In addition to the genetic evidence for the DQBI*06:02 allele, some other evidence suggests that a T cell-mediated immune mechanism destroys the orexin neurons of NT1, with CD4 + T cells being key. For this disease, traditional Chinese medicine (TCM) therapy has its own characteristics and advantages, especially the combination of acupuncture and medicine in the treatment of this disease in TCM, which has made considerable and gratifying progress. The purpose of this review is to introduce the frontier progress of neurobiology of narcolepsy, and to explore the syndrome differentiation and treatment of narcolepsy with the combined use of TCM and Western medicine combined with TCM.

Narcolepsy Treatment: Voices of Adolescents.

INTRODUCTION: Narcolepsy, characterized by excessive daytime sleepiness, is a debilitating lifelong sleep disorder for which there is no cure. Current pharmacological and nonpharmacological treatments directed toward symptom management may be suboptimal. This qualitative study explores the perspective of adolescents on therapeutic interventions for narcolepsy. METHODS: Semi-structured interviews with adolescents with narcolepsy were conducted from May to August 2019 at The Hospital for Sick Children in Toronto, Canada. Qualitative thematic analysis was utilized to generate themes emerging from the data. RESULTS: Eighteen adolescents with narcolepsy (age range = 10-17, mean age = 14.4 ± 2.0 years, 72% male) participated and 56% had cataplexy. Four prominent themes arose regarding therapeutic interventions for narcolepsy. Firstly, participants described that pharmacotherapy was moderately effective but did not fully relieve symptoms associated with narcolepsy. Secondly, while medications are the first line treatment for narcolepsy, many participants reported frustration regarding medication dependence and side effects. Thirdly, nonpharmacological strategies including scheduled sleep times and exercise were accepted and often employed. Lastly, adolescents desired more psychosocial support to address mental health sequelae of narcolepsy that were not fully managed by current treatment modalities. CONCLUSIONS: Medications were perceived as moderately effective for managing narcolepsy but almost all participants expressed concerns with taking medications due to side effects. Adolescents valued the importance of more holistic care for their narcolepsy treatment such as psychosocial support and nonpharmacological modalities. Further anticipatory guidance regarding pharmacological side effect profiles and better integration with nonpharmacological modalities are needed to improve disease control in adolescent patients.

Neurobiology of cataplexy.

Cataplexy is the pathognomonic and the most striking symptom of narcolepsy. It has originally been, and still is now, widely considered as an abnormal manifestation of rapid eye movement (REM) sleep during wakefulness due to the typical muscle atonia. The neurocircuits of cataplexy, originally confined to the brainstem as those of REM sleep atonia, now include the hypothalamus, dorsal raphe (DR), amygdala and frontal cortex, and its neurochemistry originally focused on catecholamines and acetylcholine now extend to hypocretin (HCRT) and other neuromodulators. Here, we review the neuroanatomy and neurochemistry of cataplexy and propose that cataplexy is a distinct brain state that, despite similarities with REM sleep, involves cataplexy-specific features.

Narcolepsy Type I as an autoimmune disorder.

Narcolepsy Type 1 (NT1) is hypothesized to be an autoimmune disease targeting the hypocretin/orexin neurons in the lateral hypothalamus. Ample genetic and epidemiologic evidence point in the direction of a pathogenesis involving the immune system. Many autoantibodies have been detected in blood samples from NT1 patients, but none in a consistent manner. Importantly, T cells directed toward hypocretin/orexin neurons have been detected in samples from NT1 patients. However, it remains to be seen if these potentially autoreactive T cells are also present in the hypothalamus and if they are pathogenic. For this reason, NT1 does still not fully meet the criteria for being classified as a genuine autoimmune disease, even though more and more results are pointing in that direction as will be described in this chapter. The autoimmune hypothesis has led to many attempts at slowing or stopping disease progression with immunomodulatory treatment, but so far the overall results have not been very encouraging. It is clear that more research into the pathogenesis of NT1 is needed to establish the precise role of the immune system in disease development.

Sleep disorders and the hypothalamus.

As early as the 1920s, pathological studies of encephalitis lethargica allowed Von Economo to correctly identify hypothalamic damage as crucial for the profound associated sleep-related symptoms that helped define the condition. Only over the last 3 decades, however, has the key role of the hypothalamus in sleep-wake regulation become increasingly recognized. As a consequence, a close relation between abnormal sleep symptomatology and hypothalamic pathology is now widely accepted for a variety of medical disorders. Narcolepsy is discussed in some detail as the cardinal primary sleep disorder that is caused directly and specifically by hypothalamic pathology, most notably destruction of hypocretin (orexin)-containing neurons. Thereafter, various conditions are described that most likely result from hypothalamic damage, in part at least, producing a clinical picture resembling (symptomatic) narcolepsy. Kleine-Levin syndrome is a rare primary sleep disorder with intermittent symptoms, highly suggestive of hypothalamic involvement but probably reflecting a wider pathophysiology. ROHHAD (rapid-onset obesity with hypothalamic dysfunction, hypoventilation, and autonomic dysregulation) and Prader-Willi syndrome are also covered as hypothalamic syndromes with prominent sleep-related symptoms. Finally, sleep issues in several endocrine disorders are briefly discussed.

Narcolepsy - clinical spectrum, aetiopathophysiology, diagnosis and treatment.

Narcolepsy is a rare brain disorder that reflects a selective loss or dysfunction of orexin (also known as hypocretin) neurons of the lateral hypothalamus. Narcolepsy type 1 (NT1) is characterized by excessive daytime sleepiness and cataplexy, accompanied by sleep-wake symptoms, such as hallucinations, sleep paralysis and disturbed sleep. Diagnosis is based on these clinical features and supported by biomarkers: evidence of rapid eye movement sleep periods soon after sleep onset; cerebrospinal fluid orexin deficiency; and positivity for HLA-DQB1*06:02. Symptomatic treatment with stimulant and anticataplectic drugs is usually efficacious. This Review focuses on our current understanding of how genetic, environmental and immune-related factors contribute to a prominent (but not isolated) orexin signalling deficiency in patients with NT1. Data supporting the view of NT1 as a hypothalamic disorder affecting not only sleep-wake but also motor, psychiatric, emotional, cognitive, metabolic and autonomic functions are presented, along with uncertainties concerning the 'narcoleptic borderland', including narcolepsy type 2 (NT2). The limitations of current diagnostic criteria for narcolepsy are discussed, and a possible new classification system incorporating the borderland conditions is presented. Finally, advances and obstacles in the symptomatic and causal treatment of narcolepsy are reviewed.

Sleep Disorders.

Sleep disorders are frequent and can have serious consequences on patients' health and quality of life. While some sleep disorders are more challenging to treat, most can be easily managed with adequate interventions. We review the main diagnostic features of 6 major sleep disorders (insomnia, circadian rhythm disorders, sleep-disordered breathing, hypersomnia/narcolepsy, parasomnias, and restless legs syndrome/periodic limb movement disorder) to aid medical practitioners in screening and treating sleep disorders as part of clinical practice.

Narcolepsy and Hypothalamic Region Tumors: Presentation and Evolution.

OBJECTIVE: Because most cases of brain tumor-associated narcolepsy have been published in the form of case reports or small series, the clinical presentation and evolution have not been well described. We sought to better define the epidemiology, etiology, and outcome of brain tumor-related narcolepsy. METHODS: We conducted an extensive review of the literature to identify cases of narcolepsy associated with brain tumors. Only cases of brain tumors involving the hypothalamic region including the suprasellar, sellar, and thalamus were included in this study. RESULTS: We report a child with possible narcolepsy in a child with a brain tumor. Through our literature review, we identified 25 additional cases of narcolepsy associated with brain tumors affecting the hypothalamic area. Most symptomatic narcolepsy cases were reported in children (70%). Half of the patients (13 of 25, 52%) developed narcolepsy after surgery, whereas 11 patients (44%) were symptomatic at the time of the tumor diagnosis. Ten patients had narcolepsy without cataplexy. Most cases were associated with craniopharyngioma (38%), adenoma (24%), and glioma (14%). Three, including our patient, experienced a complete resolution of symptoms. All patients underwent biopsy and were treated with adjuvant therapy. For patients with persistent symptoms, most (60%) improved following medical management of narcolepsy. CONCLUSION: This study represents the largest compilation of patients with this association. Our study allows us to better understand the etiology and outcome of patients with narcolepsy-related brain tumors.

A/H1N1 antibodies and TRIB2 autoantibodies in narcolepsy patients diagnosed in conjunction with the Pandemrix vaccination campaign in Sweden 2009-2010.

Narcolepsy is a lifelong sleep disorder related to hypocretin deficiency resulting from a specific loss of hypocretin-producing neurons in the lateral hypothalamic area. The disease is thought to be autoimmune due to a strong association with HLA-DQB1*06:02. In 2009 the World Health Organization (WHO) declared the H1N1 2009 flu pandemic (A/H1N1PDM09). In response to this, the Swedish vaccination campaign began in October of the same year, using the influenza vaccine Pandemrix(®). A few months later an excess of narcolepsy cases was observed. It is still unclear to what extent the vaccination campaign affected humoral autoimmunity associated with narcolepsy. We studied 47 patients with narcolepsy (6-69 years of age) and 80 healthy controls (3-61 years of age) selected after the Pandemrix vaccination campaign. The first aim was to determine antibodies against A/H1N1 and autoantibodies to Tribbles homolog 2 (TRIB2), a narcolepsy autoantigen candidate as well as to GAD65 and IA-2 as disease specificity controls. The second aim was to test if levels and frequencies of these antibodies and autoantibodies were associated with HLA-DQB1*06:02. In vitro transcribed and translated [(35)S]-methionine and -cysteine-labeled influenza A virus (A/California/04/2009/(H1N1)) segment 4 hemagglutinin was used to detect antibodies in a radiobinding assay. Autoantibodies to TRIB2, GAD65 and IA-2 were similarly detected in standard radiobinding assays. The narcolepsy patients had higher median levels of A/H1N1 antibodies than the controls (p = 0.006). A/H1N1 antibody levels were higher among the <13 years old (n = 12) compared to patients who were older than 30 years (n = 12, p = 0.014). Being HLA-DQB1*06:02 positive was associated with higher A/H1N1 antibody levels in both patients and controls (p = 0.026). Serum autoantibody levels to TRIB2 were low overall and high binders did not differ between patients and controls. We observed an association between levels of A/H1N1 antibodies and TRIB2 autoantibody levels particularly among the youngest narcolepsy patients (r = 0.819, p < 0.001). In conclusion, following the 2009 influenza pandemic vaccination, A/H1N1 antibody levels were associated with young age-at-onset narcolepsy patients positive for HLA-DQB1*06:02. The possibility that TRIB2 is an autoantigen in narcolepsy remains to be clarified. We could verify autoantibody responses against TRIB2 which needs to be determined in larger patient cohorts and control populations.

[Value of cerebral spinal fluid measurement of hypocretin-1 in the diagnosis of Chinese patients with narcolepsy].

OBJECTIVE: To evaluate the diagnostic value of cerebral spinal fluid (CSF) measurement of hypocretin-1 (hcrt-1) in Chinese patients with narcolepsy. METHODS: A total of 139 narcoleptic patients, including 111 narcolepsy with typical cataplexy (NC) and 28 narcolepsy without cataplexy (NWC), were diagnosed at the sleep centre of Peking University People's Hospital from April 2003 to March 2012. And 64 non-narcoleptic controls were recruited. CSF hcrt-1 levels were measured in all subjects.Receiver operating characteristic curve (ROC) was applied to determine the cutoff value of hcrt-1 for Chinese narcoleptic patients. The diagnostic utility of hcrt-1 ≤ 110.0 ng/L and hcrt-1 ≤ 30% of mean normal level defined by International Classification of Sleep Disorders-II and the new Chinese cutoff value were evaluated respectively. RESULTS: The level of hcrt-1 in narcolepsy patients was significantly lower than that of normal controls and the NC group was even lower than NWC group (20 (13, 36) vs 319 (244, 379) and 36 (15, 114) ng/L) (all P < 0.01).Using the international criteria of CSF hcrt-1 ≤ 110.0 ng/L or a level of 1/3 of mean normal control values, a specificity of 100% and sensitivity of 90.6% were generated.ROC curve indicated that CSF hcrt-1 level of 138.0 ng/L was the best cutoff value for the diagnosis of narcolepsy in Chinese narcoleptic patients. There were a specificity of 100%, a sensitivity of 92.8% and the area under the ROC curve of 0.98. CONCLUSIONS: CSF hcrt-1 measurement with high specificity and sensitivity is a useful diagnostic tool for Chinese narcoleptics. And the level of 138.0 ng/L may be the optimal cutoff for the diagnosis of narcolepsy in this group of patients.

Discriminating neurological from psychiatric hypersomnia using the forced awakening test.

INTRODUCTION: Sleep inertia refers to the inability to attain full alertness following awakening from sleep and is a major component of hypersomnia. As event-related potentials (ERPs) are correlated to the degree of consciousness, they allow exploring information processing in transitional states of vigilance. Their modifications during forced awakening (FA) context have been shown to reflect sleep inertia. OBJECTIVES: To assess the diagnostic value of a FA test using an oddball stimulation protocol during a nap in a representative sample of patients with excessive daytime sleepiness (EDS). METHODS: One hundred and seventy three patients [30 narcolepsy, 62 idiopathic hypersomnia, 33 sleep apnoea syndrome, and 48 other (mainly psychiatric) hypersomnia] performed an auditory target detection stimulation task during pre-, post-nap wakefulness, and during two successive intra-nap FA while the EEG was simultaneously recorded. Both the accuracy of target detection and the ERPs were evaluated. ERPs during forced awakening test were considered to reflect sleep inertia if they presented with a P300 delay and/or sleep negativities (N350/N550). RESULTS: Pre-nap behavior and ERPs were normal in all patients. Behavioral results were significantly worse during FA than during wakefulness for all groups of patients. P300 latencies were significantly delayed on FA conditions in each group of patients except the psychiatric group. Sensitivity and specificity for detection of sleep inertia were 64% and 94%, respectively, with predictive values of 96% (positive) and 50% (negative). CONCLUSIONS: Our results suggest that the FA test could be helpful as a diagnostic procedure for discriminating neurological from psychiatric hypersomnia.

Discovery of peptoid ligands for anti-aquaporin 4 antibodies.

Neuromyelitis optica (NMO) is an autoimmune inflammatory disorder of the central nervous system. In most NMO patients, autoantibodies to the water channel protein Aquaporin 4 (AQP4) are present at high levels and are thought to drive pathology by mediating complement-dependent destruction of astrocytes. Here, we apply recently developed chemical library screening technology to identify a synthetic peptoid that binds anti-AQP4 antibodies in the serum of NMO patients. This finding validates, in a well-defined human disease, that synthetic, unnatural ligands for the antigen-binding site of a disease-linked antibody can be isolated by high-throughput screening.

[Diagnostic and therapeutic update in narcolepsy]. / Actualizacion diagnostica y terapeutica en narcolepsia.

Narcolepsy is an emblematic, unique disease within sleep disorders that is characterised by excessive daytime sleepiness, cataplexy and other abnormal manifestations of REM sleep. In the last 14 years truly spectacular progress has been made in our knowledge of this disease, since the discovery of its cause, i.e. a loss of the hypothalamic neurons that synthesise hypocretin, a previously unknown neurotransmitter, and its probable aetiopathogenic mechanisms, i.e. an autoimmune process in a patient with very precise immunological characteristics - a specific type of HLA and a specific type of T-cell receptor. The cause of this autoimmune process remains unknown. The definitive treatment - the administration of hypocretin, which is the substance missing in the organism - is still unavailable, but there are powerful drugs for treating its main symptoms, the sleepiness and the cataplexy. Some of these are classic compounds (methylphenidate, clomipramine), while others are more recent (modafinil, venlafaxine, sodium oxybate), but together they allow many patients to experience significant improvements. Lack of knowledge about the disease, both on the part of patients and their relatives as well as physicians, is the reason for the great delay in its diagnosis, with even more dramatic consequences when the disease begins in infancy.

Possible mechanism of secondary narcolepsy with a long sleep time following surgery for craniopharyngioma.

A 19-year-old woman suffered from severe excessive daytime sleepiness accompanied with long sleep episodes both in the daytime and nighttime and frequent episodes of cataplexy shortly after the removal of craniopharyngioma in the intrasellar space. Multiple sleep latency test showed a typical finding of narcolepsy, and cerebrospinal fluid orexin concentration was below the narcolepsy cut-off value. MRI-tractography showed a clear lack of neuronal fiber connections from the hypothalamus to the frontal lobe. SPECT using (123)I-IMP showed frontal hypoperfusion. These connection damages could have been responsible for the occurrence of narcolepsy-like symptoms and long daytime sleep episodes in this case.

Narcolepsy in the pediatric population.

Narcolepsy is characterized by excessive daytime sleepiness, with or without cataplexy. Associated features include sleep paralysis, hypnagogic or hypnopompic hallucinations, and disturbed nocturnal sleep. Narcolepsy is strongly associated with the HLA DQB1*0602 allele, and its symptoms stem from destruction of hypocretin-secreting neurons in the hypothalamus. Recently identified autoantibodies to Tribbles homologue 2 in some patients, as well as cases associated with H1N1 vaccination, support an autoimmune mechanism. There are many challenges in diagnosing and treating pediatric narcolepsy. Caution must also be used in interpreting polysomnography and multiple sleep latency test results in children. HLA testing is nonspecific, and no commercial test exists to measure cerebrospinal fluid hypocretin levels. Neuroimaging has not yet proven useful in primary narcolepsy. Treatment of sleepiness and cataplexy in children requires extrapolating from adult studies. Hopefully, further insights into the pathophysiology of narcolepsy will allow for new therapeutics to manage the symptoms and modify the course of the disease.

Melanin concentrating hormone in central hypersomnia.

BACKGROUND: Narcolepsy with cataplexy (NC) is a disabling disorder characterized by excessive daytime sleepiness and abnormal rapid eye movement (REM) sleep manifestations, due to a deficient hypocretin/orexin neurotransmission. Melanin concentrating hormone (MCH) neurons involved in the homeostatic regulation of REM sleep are intact. We hypothesized that an increased release of MCH in NC would be partly responsible for the abnormal REM sleep manifestations. METHODS: Twenty-two untreated patients affected with central hypersomnia were included: 14 NC, six idiopathic hypersomnia with long sleep time, and two post-traumatic hypersomnia. Fourteen neurological patients without any sleep disorders were included as controls. Using radioimmunoassays, we measured hypocretin-1 and MCH levels in cerebrospinal fluid (CSF). RESULTS: The MCH level was slightly but significantly lower in patients with hypersomnia (98 ± 32 pg/ml) compared to controls (118 ± 20 pg/ml). After exclusion of patients affected with post-traumatic hypersomnia the difference became non-significant. We also failed to find any association between MCH level and hypocretin level, the severity of daytime sleepiness, the number of SOREMPs, the frequency of cataplexy, and the presence of hypnagogic hallucinations or sleep paralysis. CONCLUSION: This study reports the first measurement of MCH in CSF using radioimmunoassay technology. It appears to be a non-informative tool to differentiate etiologies of central hypersomnia with or without REM sleep dysregulation.

Olfactory dysfunction in narcolepsy with and without cataplexy.

BACKGROUND: Not only patients in whom REM behavior disorder (RBD) is associated with narcolepsy, but also those with narcolepsy alone are reported to have olfactory dysfunction. We investigated if hyposmia is specific to narcolepsy with cataplexy (N-C) or if narcolepsy without cataplexy (NwC) is also associated with olfactory dysfunction. METHODS: We studied olfactory function in two groups of patients: N-C group (n=66, 26 men and 40 women; mean age 41+/-18 years), and NwC group (n=17, 7 men and 10 women; mean age 46+/-20 years). As a control group we used published normative data for particular smell tests. RESULTS: Both patients with N-C and patients suffering from NwC had a significantly higher olfactory threshold (N-C group, p<0.0001; NwC group, p<0.0001) and impaired odor identification (N-C group, p<0.0001; NwC group, p<0.0001). Our results show for the first time that narcolepsy without cataplexy, where the majority of cases have normal CSF hypocretin levels, is associated with olfactory dysfunction. CONCLUSIONS: It appears that also a partial loss of hypothalamic hypocretin neurons without a clear CSF level decrease can affect smell projection.