Narcolepsy and psychosis; case report

Narcolepsy is an infrequent neurological disorder, included in the catalog of rare diseases. Despite the existenceof precise diagnostic criteria, this entity remains underdiagnosed. It is characterized by excessive daytime sleepiness associated with cataplexy; in some cases, hypnagogic or hypnopompic hallucinations, auditory hallucinations, and/or delusional ideation may appear. The occurrence of psychotic symptoms makes differential diagnosis extremely difficult (narcolepsy, schizophrenia, or both). Furthermore, therapeutic management may be complex, since the treatment of one of the disorders may worsen the other. Here we describe the case of a patient with this rare comorbidity, which illustrates the major difficulties associated to both differential diagnosis and therapeutic management once a definitive diagnosis has been reached.

Late Diagnosis of Narcolepsy With Cataplexy: A Novel Case of Cataplectic Facies Presenting in an Elderly Woman

None

Cataplectic facies is an unusual feature described in children with narcolepsy and cataplexy. The typical manifestations of cataplectic facies consist of repetitive mouth opening, tongue protrusion, and ptosis. An interesting observation is that the usual emotional triggers associated with cataplexy such as laughter and joking are not always present, thus hampering diagnosis of the underlying syndrome. Cataplectic facies is thought to be a phenomenon observed in the early stages of narcolepsy type 1 and is thought to disappear by the time the patient reaches puberty. We present a unique case of an elderly woman with narcolepsy type 1 demonstrating cataplectic facies. The novel circumstances of this case highlight that facial cataplexy can present later in life, in contrast with previous descriptions that report resolution of cataplectic facies before puberty. Wider recognition of these features throughout the life course may aid in accurate diagnosis and thereby ensure swift access to appropriate treatment.

Status Cataplecticus Following Abrupt Withdrawal of Clomipramine

Presentation This is a case of a 31 year old gentleman who suffered an attack of status cataplecticus following abrupt withdrawal of clomipramine. Diagnosis Clomipramine was temporarily discontinued in order to confirm a suspected diagnosis of narcolepsy using Multiple Sleep Latency Testing. This precipitated an episode of status cataplecticus which resolved with re-introduction of therapy. A diagnosis of narcolepsy was later confirmed with undetectable levels of hypocretin/orexin in the CSF. Treatment Re-introduction of clomipramine led to resolution of status cataplecticus. The patient now remains stable with regards to his cataplexy on clomipramine 30mg. Discussion There have been a total of 4 case reports of status cataplecticus following withdrawal of antidepressant therapy. In all cases, reintroduction of anti-cataplectic therapy led to resolution of attacks. The abrupt discontinuation of an SSRI is believed to precipitate cataplexy attacks due to reduction in noradrenergic tone.

Sleep assessments for a mild traumatic brain injury trial in a military population

Baseline sleep characteristics were explored for 71 U.S. military service members with mild traumatic brain injury (mTBI) enrolled in a post-concussive syndrome clinical trial. The Pittsburgh Sleep Quality Index (PSQI), sleep diary, several disorder-specific questionnaires, actigraphy and polysomnographic nap were collected. Almost all (97%) reported ongoing sleep problems. The mean global PSQI score was 13.5 (SD=3.8) and 87% met insomnia criteria. Sleep maintenance efficiency was 79.1% for PSQI, 82.7% for sleep diary and 90.5% for actigraphy; total sleep time was 288, 302 and 400 minutes, respectively. There was no correlation between actigraphy and subjective questionnaires. Overall, 70% met hypersomnia conditions, 70% were at high risk for obstructive sleep apnea (OSA), 32% were symptomatic for restless legs syndrome, and 6% reported cataplexy. Nearly half (44%) reported coexisting insomnia, hypersomnia and high OSA risk. Participants with post-traumatic stress disorder (PTSD) had higher PSQI scores and increased OSA risk. Older participants and those with higher aggression, anxiety or depression also had increased OSA risk. The results confirm poor sleep quality in mTBI with insomnia, hypersomnia, and OSA risk higher than previously reported, and imply sleep disorders in mTBI may be underdiagnosed or exacerbated by comorbid PTSD.

[Not Available]

Zusammenfassung. Narkolepsie ist eine lebenslange Schlaf-Wach-Störung, charakterisiert durch exzessive Tagesschläfrigkeit und Episoden mit plötzlichem Muskeltonusverlust bei starken Emotionen (Kataplexie). Weitere Symptome sind Schlafparalyse, Halluzinationen und fragmentierter Nachtschlaf. Die Diagnose der Narkolepsie wird primär klinisch gestellt und durch zwei biologische Marker unterstützt: erstens durch Dokumentation von verfrühtem REM-Schlaf in der Schlaflaboruntersuchung, und zweitens durch Verlust des hypothalamischen Peptids Hypocretin in der Liquoruntersuchung. Ferner besteht eine genetische Prädisposition bei Positivität für das HLA DQB1*0602-Allel. Die Symptome der Narkolepsie können mit anderen psychiatrischen, neurologischen oder Schlaf-Wach-Störungen verwechselt werden. Die richtige Diagnosestellung ist entscheidend für die Einleitung einer wirksamen Therapie; gleichzeitig kann bei Patienten ohne Narkolepsie eine unnötige Behandlung mit psychoaktiven Substanzen, manche davon mit einem hohen Missbrauchsrisiko, vermieden werden.

Environmental factors in the development of narcolepsy with cataplexy. A case-control study

INTRODUCTION

Epidemiological studies suggest the importance of environmental factors in the etiology of narcolepsy-cataplexy in genetically predisposed subjects.

AIM

To assess the role of environmental factors in the development of narcolepsy-cataplexy, using a case-control design with control subjects being matched for ethnicity and age.

PATIENTS AND METHODS

All patients were recruited through two outpatient clinics at the community of Madrid, ant the diagnosis of narcolepsy fulfilled the criteria of the International Classification on Sleep Disorders-2005. A questionnaire, including 54 environmental psychological stressor life events and 42 infectious diseases items, was administered to 54 patients. We specifically assessed the stressful factors and infectious diseases that occurred in the year preceding the onset of the first symptom of narcolepsy (excessive daytime sleepiness and/or cataplexy). The same questionnaire was administered to 84 control subjects recruited from non-related family members of the same community.

RESULTS

Fifty four patients (55.6% males) answered the questionnaire, The mean age at onset of the first symptom was 21.6 ± 9.3 years, and the mean age at diagnosis was 36.5 ± 12.4 years. The main finding in narcoleptic patients as compared to control subjects was major changes in the 'number of arguments with partner, family, or friends' (odds ratio: 5.2; 95% confidence interval: 1.8-14.5). This can be interpreted as having a protective function and it suggests that psychological mechanisms are present since the beginning of the disease. As for the infectious factors, chickenpox was the most frequently reported. No significant differences were found in terms of total numbers of stress-related and infectious factors between cases and controls.

CONCLUSION

Prospective studies regarding the interaction between environmental and genetic factors are warranted.

Noninvasive detection of sleep/wake changes and cataplexy-like behaviors in orexin/ataxin-3 transgenic narcoleptic mice across the disease onset

Sleep and behavioral monitoring of young mice is necessary for understating the progress of symptoms in congenital and acquired diseases associated with sleep and movement disorders. In the current study, we have developed a non-invasive sleep monitoring system that identifies wake and sleep patterns of newborn mice using a simple piezoelectric transducer (PZT). Using this system, we have succeeded in detecting age-dependent occurrences and changes in sleep fragmentation of orexin/ataxin-3 narcoleptic mice (a narcoleptic mouse model with postnatal hypocretin/orexin cell death) across the disease onset. We also detected REM sleep/cataplexy patterns (i.e., immobility with clear heartbeat [IMHB] signals due to the flaccid posture) by the PZT system, and found that sudden onset of REM sleep-like episodes specifically occur in narcoleptic, but not in wild type mice, suggesting that these episodes are likely cataplexy. In contrast, gradual onset of IMHB likely reflects occurrence of REM sleep. In summary, we have shown that the PZT system is useful as a non-invasive sleep and behavior monitoring system to analyze the developmental aspects of sleep and movement disorders in mice models.

Pharmacological management of narcolepsy and cataplexy in pediatric patients

Narcolepsy is a neurological disorder frequently occurring from childhood and persisting through adolescence and adulthood. Individuals suffering from narcolepsy exhibit excessive daytime somnolence, sleep attacks, cataplexy, dysomnia, metabolic perturbations including weight gain, and problems in social interaction and academic performance. The prevalence of narcolepsy in childhood is not known but can be estimated from adult studies to be greater than 20-60 per 100,000 in Western countries. The 2009 (A) H1N1 vaccination campaign led to an increase of narcoleptic cases both in children and in adults, supporting the autoimmune hypothesis of the disease. This article focuses on the epidemiology, etiology, and particularities of treatment in pediatric narcolepsy and details the effects of the drugs used to treat this condition, including recent trends in the field. Future therapeutic directions are also discussed. At present, medications used to treat children or adolescents have shown efficacy mostly based on clinical experience, given the lack of level 1 evidence-based studies in the pediatric population. Therefore, most compounds used in adult narcolepsy to target clinical symptoms such as wake-promoting or anticataplectic agents are prescribed off-label in pediatric patients. Published research shows the benefit of drug therapy for narcoleptic children, but these must be dispensed with caution in the absence of well conducted clinical trials.

Differences in brain morphological findings between narcolepsy with and without cataplexy

Objective

Maps of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) obtained by diffusion tensor imaging (DTI) can detect microscopic axonal changes by estimating the diffusivity of water molecules using magnetic resonance imaging (MRI). We applied an MRI voxel-based statistical approach to FA and ADC maps to evaluate microstructural abnormalities in the brain in narcolepsy and to investigate differences between patients having narcolepsy with and without cataplexy.

Methods

Twelve patients with drug-naive narcolepsy with cataplexy (NA/CA), 12 with drug-naive narcolepsy without cataplexy (NA w/o CA) and 12 age-matched healthy normal controls (NC) were enrolled. FA and ADC maps for these 3 groups were statistically compared by using voxel-based one-way ANOVA. In addition, we investigated the correlation between FA and ADC values and clinical variables in the patient groups.

Results

Compared to the NC group, the NA/CA group showed higher ADC values in the left inferior frontal gyrus and left amygdala, and a lower ADC value in the left postcentral gyrus. The ADC value in the right inferior frontal gyrus and FA value in the right precuneus were higher for NA/CA group than for the NA w/o CA group. However, no significant differences were observed in FA and ADC values between the NA w/o CA and NC groups in any of the areas investigated. In addition, no correlation was found between the clinical variables and ADC and FA values of any brain areas in these patient groups.

Conclusions

Several microstructural changes were noted in the inferior frontal gyrus and amygdala in the NA/CA but not in the NA w/o CA group. These findings suggest that these 2 narcolepsy conditions have different pathological mechanisms: narcolepsy without cataplexy form appears to be a potentially broader condition without any significant brain imaging differences from normal controls.

[Adult psychiatric aspects of Niemann-Pick disease]

Niemann-Pick disease (NPD) is a group of distinct rare disorders (i.e. NPD-A; NPD-B; NPD-C) - with autosomal recessive inheritance pattern - within the class of the inborn disorders of the sphingolipid metabolism (called sphingolipidoses). Since patients with NPD-A do not survive into adulthood and most patients with NPD-B are free from neuropsychiatric symptoms we discuss only briefly type-A and -B NPD and mainly constrict our review discussing the neuropsychiatric symptoms along with the pathomechanism and the treatment of NPD-C. NPD-C is clinically heterogeneous, with notable variations in age at onset, course and symptoms. Along with systemic signs, neurologic and psychiatric symptoms are quite frequent in NPD-C and in its adult form sometimes psychiatric symptoms are the first ones appearing. Unfortunately, the majority of clinicans (including adult psychiatrists and neurologists) are not aware of the symptom group characteristic to NPD-C so patients with this disorder are frequently misdiagnosed in the clinical practice. Since neuropsychiatric manifestations of NPD-C may be treated with a substrate reduction agent (miglustat) with greater awareness of the identification of neuropsychiatric symptoms in due course is the prerequisite of proper and early diagnosis and treatment.

Effects of orexin gene transfer in the dorsolateral pons in orexin knockout mice

STUDY OBJECTIVES

Narcolepsy is a sleep disorder characterized by loss of orexin neurons. Previously, our group demonstrated that transfer of the orexin gene into surrogate neurons in the lateral hypothalamus and the zona incerta significantly reduced cataplexy bouts in the orexin-ataxin-3 mice model of narcolepsy. The current study determined the effects of orexin gene transfer into the dorsolateral pontine neurons in the orexin knockout (KO) mice model of narcolepsy. The dorsolateral pons was chosen because it plays a critical role in regulating muscle tone and thus it is conceivable to be involved in cataplexy as well. Cataplexy is the pathognomonic symptom in narcolepsy.

DESIGN

Independent groups of orexin KO mice were given bilateral microinjections (0.75 μL each side) of either recombinant adenoassociated virus-orexin (rAAV-orexin; n = 7), or rAAV-green fluorescent protein (rAAV-GFP; n = 7) into the dorsolateral pons. A group of orexin KO mice that did not receive rAAV (n = 7) and a group of wild-type mice (C57BL/J6; n = 5) were used as controls. Three weeks after rAAV-mediated gene transfer narcolepsy symptoms were examined using sleep and behavioral recordings. Number, location of the orexin-immunoreactive neurons, and relative density of orexin immunoreactive fibers were determined.

MEASUREMENTS AND RESULTS

Orexin gene transfer into the dorsolateral pons significantly decreased cataplexy and modestly improved wake maintenance compared to the orexin KO mice that did not receive rAAV. In contrast, GFP gene transfer worsened narcoleptic symptoms compared to the no-rAAV orexin KO group.

CONCLUSION

Orexin gene transfer into the dorsolateral pontine neurons can control cataplexy attacks and modestly improve wake maintenance.

[Diagnostic and therapeutic update in narcolepsy]

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.

Isolated cataplexy and REM sleep behavior disorder after pontine stroke

Cataplexy is a complex neurologic phenomenon during wakefulness probably resulting from impairment of pontine and hypothalamic control over muscle tone. REM sleep behavior disorder (RSBD) is characterized by the presence of REM sleep without atonia manifesting clinically as disruptive or injurious behaviors. We present here a patient with both cataplexy and RSBD following pontine encephalomalacia. The clinical presentation provides insight into the possible pathobiology of both waking and sleeping disorders of REM sleep regulation.

Diagnostic ambiguities in a case of post-traumatic narcolepsy with cataplexy

Narcolepsy arising from trauma can present particular problems of differential diagnosis. In this case study presentation the patient suffered a head trauma, without unconsciousness, and began to experience unusual episodic behaviours. Symptom presentation differed from the typical clinical manifestations of idiopathic narcolepsy leading to an 8-year search for a definitive diagnosis. Key relevant aspects that led to diagnostic ambiguities were the order of symptom development, negative for the antigen HLA DR2, significance of the Multiple Sleep Latency Test (MSLT) mean sleep latency versus number of sleep onset rapid eye movement periods, the somewhat atypical features of cataplexy, the coexistence of sleep apnoea, and the mildness of the original head injury. It is argued that cases of post-traumatic narcolepsy should be considered in the context of their clinical development over time and that practitioners should be aware that this form of narcolepsy can differ from the typical clinical history of idiopathic narcolepsy.

[Integrated treatment of the symptoms of narcolepsy-cataplexy syndrome with sodium oxybate]

INTRODUCTION

Treatment of narcolepsy-cataplexy is based on the use of different drugs that either stimulate or modify REM sleep, which makes it possible to improve the symptoms that characterise the disease.

AIM

To present the characteristics of sodium oxybate, a new drug that has been approved in the United States and in the European Union for use in treating narcolepsy-cataplexy; the main contribution made by this new agent is the possibility of acting on all the symptoms of the disease at the same time.

DEVELOPMENT

In four randomised, double-blind, placebo-controlled studies and with a class A level of evidence, sodium oxybate has proved to be effective in improving the cardinal symptoms of narcolepsy-cataplexy, that is to say, hypersomnia, cataplexy and fragmentation of nocturnal sleep. Treatment was well tolerated and the side effects, consisting mainly of nausea or symptoms related with the nervous system, such as anxiety, depression, confusion or drowsiness, were mild or moderate in most cases and rarely led to the patient's giving up the treatment. The drug has a favourable pharmacokinetic profile, with little potential to interact with other pharmaceuticals. It seems to have a synergic effect with modafinil, boosting its effects in the treatment of excessive sleepiness. Although it is a substance that has been used as a recreational drug, no cases of addiction or drug abuse have been observed in narcoleptic patients treated in a controlled manner.

CONCLUSIONS

Sodium oxybate can be considered to be a first-choice drug in the treatment of narcolepsy-cataplexy.

The epidemiology of narcolepsy

Much has been learned about the pathophysiology of narcolepsy over the last several decades. It is likely that hypocretin-producing cells in the lateral hypothalamus are selectively destroyed in genetically susceptible individuals carrying 1 or more alleles of HLA DQB1*0602. Despite advances, the causes of narcolepsy and how to prevent it remain elusive. Classic epidemiology aims not only to enumerate occurrence of disease in populations, but also to identify etiologic risk factors. This review details what the application of classic epidemiology has taught us so far about narcolepsy and suggests directions for future studies to clarify its etiology. The prevalence of narcolepsy with cataplexy has been examined in many studies and falls between 25 and 50 per 100,000 people. Information on incidence is limited, with 1 study finding the incidence of narcolepsy with cataplexy to be 0.74 per 100,000 person-years. The search for etiologic risk factors has yet to yield important associations. Factors most thoroughly examined include body mass index, immune responses, and stressful life events. Such associations may reflect a consequence rather than a cause of disease. As with other diseases characterized by selective cell loss, such as Parkinson disease or type 1 diabetes mellitus, narcolepsy is likely caused by environmental exposures before the age of onset in genetically susceptible individuals. Matching efforts in these other diseases and using large well-designed epidemiologic studies of narcolepsy, investigators must intensify the search for these exposures, focusing on the first 2 decades of life. Identification of modifiable risk factors will help to prevent this disease.

Cataplexy Emotional Trigger Questionnaire (CETQ)--a brief patient screen to identify cataplexy in patients with narcolepsy

STUDY OBJECTIVES

This pilot study explored the sensitivity and specificity of a brief survey to determine the presence of cataplexy. We hypothesized that the brief questionnaire could provide a quick, sensitive, and specific screening tool to identify those patients with cataplexy, which would result in more timely referrals for further diagnostic testing.

DESIGN

The pilot study utilized a brief questionnaire that was developed by including 5 questions that were found to be strong positive predictors of cataplexy from a previous 51-item cataplexy questionnaire.

SETTING

Participants with a laboratory-confirmed diagnosis completed the questionnaire via mail correspondence or at the time of scheduled appointments in the Mayo Clinic Sleep Disorder Center, Rochester, Minn.

PARTICIPANTS

Seventy-eight patients with narcolepsy and cataplexy and 78 patients with obstructive sleep apnea completed the questionnaire.

INTERVENTIONS

NA.

MEASUREMENTS AND RESULTS

The sensitivity, specificity, area under the curve, positive predictive value, and negative predictive value/were computed for each question individually, along with appropriate 95% confidence intervals.

CONCLUSIONS

The first item of the cataplexy emotional trigger questionnaire (CETQ) discriminates patients with cataplexy from controls with excellent sensitivity and specificity. The addition of the other 4 questions, in the context of question 1, did not improve specificity, area under the curve, positive predictive value, or negative predictive value but did provide useful confirmatory data. Thus, a single question provides a brief practical tool that could improve the recognition of cataplexy in the clinical setting. Depending on the circumstance, users may be interested in utilizing 1 or all 5 questions.

Prazosin increases immobility episodes in taiep rats without changes in the properties of α1 receptors

The taiep rat is a myelin mutant in which immobility episodes (IEs) can be induced in adult males by gripping. EEG recordings during gripping-induced IEs show a rapid eye movement (REM) sleep-like pattern, similar to that reported for narcolepsy-cataplexy suggesting that IEs represent a disorder of REM-sleep. An alpha(2) adrenoceptor agonist increases gripping-induced IEs, whereas alpha(2) antagonists decrease these. We have studied the effect of prazosin on IEs and the levels of alpha(1) adrenoceptors were evaluated in cerebro-cortical homogenates of taiep and control rats. Systemic administration of prazosin results in a significant increase in both the frequency and duration of gripping-induced IEs. Our results show that cerebro-cortical tissue is not an adequate candidate for the expression of cataplexy-like symptoms, but prazosin, an alpha(1) antagonist, is a potent inducer of gripping-induced immobility episodes in taiep rats.

Niemann-Pick Disease Type C: Cataplexy and Hypocretin in Cerebrospinal Fluid

Niemann-Pick disease type C (NPC) is an inherited lipid storage disorder, characterized by a defect in intracellular trafficking of exogenous cholesterol that leads to the lysosomal accumulation of unesterified cholesterol. We report a Japanese patient with NPC caused by a homozygous c.2974 G > T mutation of the NPC1 gene, which predicts a glycine (GGG) to tryptophan (TGG) change at codon 992 (designated as p.G992W). This is a well-known NPC1 gene mutation that causes a unique phenotype of NPC, which has been limited to a single Acadian ancestor in Nova Scotia, Canada. Our patient characteristically started presenting with cataplexy at the age of 9 years. Recent studies have shown reduced hypocretin-1 levels in the cerebrospinal fluid (CSF) of narcoleptic patients with cataplexy. In our patient, the level of hypocretin-1 was determined as moderately low, 174 pg/ml (normal, > 200 pg/ml). To date, CSF levels of hypocretin-1 have been determined by using an identical assay method in 7 cases of NPC, including our case. All of the NPC cases with cataplexy demonstrated low levels of CSF hypocretin-1, confirming the association of reduced CSF hypocretin-1 levels with cataplexy in NPC.

Characterizing the emotions that trigger cataplexy

Cataplexy is an intriguing example of how emotions can trigger muscle weakness by activating neural pathways. When associated with excessive daytime sleepiness, cataplexy is considered pathognomonic of narcolepsy. A questionnaire was administered to 55 patients with narcolepsy-cataplexy and 47 comparison subjects with obstructive sleep apnea. The area under the receiver-operating curve was 0.94 for the combination of muscle weakness with laughter and ability to hear during the episode. A 51-item questionnaire succeeds in identifying cataplexy in narcolepsy-cataplexy patients measured up against a comparison group. In the future, an abbreviated survey with these two questions should identify cataplexy with high sensitivity and specificity. These selected questions could subsequently be included into screening tools for use with different patient populations.

Emerging drugs for narcolepsy

Narcolepsy is characterised by excessive daytime sleepiness, usually associated with cataplexy, hypnagogic hallucinations, sleep paralysis and fragmented nocturnal sleep. Although uncommon, it results in significant disability. Most cases occur sporadically, but genetic factors probably form a susceptibility background on which unknown environmental triggers act. The hypocretin system is strongly implicated in the development of narcolepsy. Cerebrospinal fluid levels of hypocretin-1 are significantly reduced in narcoleptic subjects with cataplexy. Despite the advances in our understanding of narcolepsy, current therapy is primarily symptomatic. Stimulants (standard and novel) combat excessive daytime sleepiness. Antidepressants (tricyclics, dual-action or selective serotonin re-uptake inhibitors) and sodium oxybate are anticataplexy agents. Hypnagogic hallucinations and sleep paralysis respond to antidepressants. Sodium oxybate consolidates sleep. Novel and experimental treatments include histamine antagonists, hypocretin agonists, slow-wave sleep enhancers, intravenous gamma-globulin, tramadol and corticosteroids.

In vivo evidence of neuronal loss in the hypothalamus of narcoleptic patients

A dysfunction of the orexin (hypocretin) system in the hypothalamus has recently been linked to the pathogenesis of narcolepsy. The authors used in vivo proton MR spectroscopy to assess the N-acetylaspartate (NAA) content in the hypothalamus of narcoleptic patients. Hypothalamic NAA/creatine-phosphocreatine was reduced in narcoleptic patients compared with control subjects (p < 0.01). Hypothalamic neuronal loss/damage is a central pathogenetic feature in narcolepsy.

Sleep disorders

Patients with sleep disorders present with a variety of complaints including excessive daytime sleepiness, daytime spells, inability to sleep, uncomfortable sensation in the extremities, and unusual night time behaviors. This article provides eight vignettes on patients with sleep disorders including narcolepsy, idiopathic hypersomnia, obstructive sleep apnea, restless legs syndrome, and rapid eye movement behavior disorder. The discussion provides data regarding the epidemiology, pathophysiology, and diagnostic approach for these conditions. The various treatment options for these sleep disorders are also identified.

Narcolepsy

Narcolepsy is a chronic disorder of EDS. All patients experience EDS. Other symptoms include cataplexy, sleep paralysis, hypnagogic hallucinations, and disrupted nocturnal sleep. Treatment, usually with stimulants and low-doses of antidepressant medications, can dramatically improve the patient's quality of life. Although only advanced practice nurses may be actively involved in the diagnosis and treatment of this disorder, all nurses can encourage their patients who complain of EDS to consult a specialist in sleep disorders medicine, provide emotional support after diagnosis, and educate patients and their families about narcolepsy and its treatment.

An immersive simulation system for provoking and analyzing cataplexy

Cataplexy, a sudden loss of voluntary muscle control, is one of the hallmark symptoms of narcolepsy, a sleep disorder characterized by excessive daytime sleepiness. Cataplexy is usually triggered by strong, spontaneous emotions, such as laughter, surprise, fear or anger, and is more common in times of stress. The Sleep Disorders Unit and the Biomedical Imaging Resource at Mayo Clinic are developing interactive display technology for reliably inducing cataplexy during clinical monitoring. The use of immersive displays may help bypass patient defenses, and game-like "unreality" allows introduction of surprising, threatening, or humorous elements, with little risk of offending patients. The project is referred to as the "Cataplexy/Narcolepsy Activation Program", or CatNAP. We have developed an automobile driving simulation to allow the introduction of humorous, surprising, or stress-inducing events and objects as the patient attempts to navigate a simulated vehicle through a virtual town. The patient wears a stereoscopic head-mounted display, by which he views the virtual town through the windows of his simulated vehicle. The vehicle is controlled via a driving simulator steering wheel and pedal cluster. The patient is instructed to drive his vehicle to another location in town, given initial directions and street signs. As he attempts to accomplish the task, various objects, sounds or conditions occur which may distract, startle, frustrate or cause laughter; responses which may trigger a cataplectic episode. The patient can be monitored by reflex tests and EMG recordings during the driving experience. An evaluation phase with volunteer patients previously diagnosed with cataplexy has been completed. The goal of these trials was to gain insight from the volunteers as to improvements that could be made to the simulation. All patients that participated in the evaluation phase have been under a physician's care for a number of years and control their cataplexy with medication. We believe this is a novel and innovative approach to a difficult problem. CatNAP is a compelling example of the potentially effective application of virtual reality technology to an important clinical problem that has resisted previous approaches. Preliminary results suggest that an immersive simulation system like CatNAP will be able to reliably induce cataplexy in a controlled environment. The project is continuing through a final stage of refinement prior to conducting a full clinical study.

Narcolepsy -- cataplexy and psychoanalytic theory of sleep and dreams

Narcolepsy had been documented some twenty years before the psychoanalytic movement, emphasizing the central role of sleep and dreams in the understanding of mental health, offered an entirely novel theory of its aetiology. And when the full range of the behavioral aspects of the condition were documented, it was obvious that intense psychoanalytic interest in it was inevitable. Unfortunately, even mainstream neurology, lacking any rival physiological explanation, for a time tended to entertain a definite role for such beliefs, at least in some cases. However, such a theory involving outre concepts of repressed, guilt-ridden sexual drives as an explanation of the behavioral aspects of narcolepsy-cataplexy, of necessity simply added to the burdens of the sufferer. For it became clear that the condition by itself produced enough psycho-social problems without further adding to them. This historical note details the persistence of this misconceived theory up to the later decades of this century, and the burden that it placed upon those who suffered from this condition.

Weak with laughter

We found a marked reduction of H-reflex amplitude during laughter, suggesting that motor inhibition may underlie the feeling of being "weak with laughter". This effect may have a role in cataplexy, which is preferentially elicited by laughter.

[Hypersomnia. Narcolepsy-cataplexy (Gélineau syndrome)]

SIGNS AND SYMPTOMS

Narcolepsy is the most prevalent of the primary disorders of vigilance. It is relatively easy to identify in presence of clearcut cataplexy and other REM-sleep related symptoms, i.e. sleep paralysis and hypnagogic hallucinations. Otherwise, one must rely on demonstration of sleep onsets in REM during night and daytime polygraphy, and on the very strong association with the HLA gene DQB1*0602.

TREATMENT

With the advent of modafinil, treatment of narcolepsy has been substantially modified. New strategies are an improvement over amphetamines both in terms of side effects and long-term outcome. Most cataplectic attacks can be controlled by tricyclics or other antidepressants.

PATHOGENESIS

Major advances in pathophysiology and etiology have been obtained through an animal model of the disease, canine narcolepsy. Pharmacological studies point to the importance of alpha-1 adrenergic mechanisms in cataplexy, while dopaminergic systems seem more involved in generating sleepiness. As concerns genetics of this autosomal recessive disease, there is an equivalent of the human HLA association in the form of an immunoglobulin gene (mu-switch) linkage. Narcolepsy research is now looking for other genes, for which familial cases may give clues.

Familial aspects of narcolepsy-cataplexy in the Czech Republic

A group of 153 probands with narcolepsy included 38 subjects (24.8%) with a familial incidence of excessive daytime sleepiness (EDS). In 15 cases (9.8%), at least one additional family member suffered from narcolepsy-cataplexy; only EDS was present in the remaining 23 cases (15.0%). One thousand eighty-two relatives were evaluated. The percentage of first degree relatives affected with narcolepsy-cataplexy was 2.28% (1.20% if only clinically confirmed cases were accounted); the adequate value for second degree relatives was 1.49%. The occurrence of EDS exceeded these values several times (4.28% in first degree relatives, 6.57% in second degree relatives). The vertical mode of transmission was found in most families. Human leukocyte antigen (HLA) typing was performed in six families with multiple-case incidence of narcolepsy. Forty-one blood samples were analyzed (12 patients with narcolepsy, 7 with only EDS, 2 with sleep apnea syndrome, and 20 healthy relatives). HLA DR2+ and DQB1*0602+ were found in only 8 out of 12 narcoleptic patients with cataplexy and in six out of seven patients with isolated attacks of sleepiness. These findings support the hypothesis that there is a common genetic basis for narcolepsy associated with cataplexy and "monosymptomatic" forms of narcolepsy and suggest the existence of non-major histocompatibility complex (MHC) susceptibility factors for narcolepsy.

HLA DQB1*0602 is associated with cataplexy in 509 narcoleptic patients

Narcolepsy is a sleep disorder associated with HLA DR15 (DR2) and DQB1*0602. We HLA typed 509 patients enrolled in a clinical trial for the drug modafinil and analyzed the results in relation to cataplexy, a symptom of narcolepsy characterized by muscle weakness triggered by emotions. The patients were either subjects with cataplexy who had a mean sleep latency (SL) of less than 8 minutes and two or more sleep onset rapid eye movement (REM) periods (SOREMPs) during a multiple sleep latency test, or narcoleptic patients without cataplexy but with a mean SL shorter than 5 minutes and two or more SOREMPs. The respective values of DRB1*15 (DR2) and DQB1*0602 as markers for narcolepsy were first compared in different ethnic groups and in patients with and without cataplexy. DQB1*0602 was found to be a more sensitive marker for narcolepsy than DRB1*15 across all ethnic groups. DQB1*0602 frequency was strikingly higher in patients with cataplexy versus patients without cataplexy (76.1% in 421 patients versus 40.9% in 88 patients). Positivity was highest in patients with severe cataplexy (94.8%) and progressively decreased to 54.2% in patients with the mildest cataplexy. A voluntary 50-item questionnaire focusing on cataplexy was also analyzed in 212 of the 509 HLA-typed patients. Subjects with definite cataplexy as observed by an experienced clinician were more frequently HLA DQB1*0602-positive than those with doubtful cataplexy, and the manifestations of cataplexy were clinically more typical in DQB1*0602-positive patients. These results show that the HLA association is as tight as previously reported (85-95%) when cataplexy is clinically typical or severe. We also found that patients with mild, atypical, or no cataplexy have a significantly increased DQB1*0602 frequency (40-60%) in comparison with ethnically matched controls (24%). These results could be explained by increased disease heterogeneity in the noncataplexy group or by a direct effect of the HLA DQB1*0602 genotype on the clinical expression of narcolepsy.

Symptom description and management in narcolepsy

Narcolepsy is a neurologic condition that is chronic and lifelong. The study reported describes the experience of living with the most prevalent symptoms of narcolepsy and the management strategies employed for those symptoms by persons with narcolepsy. Descriptions of living with excessive daytime sleepiness, sleep attacks, and cataplexy are given. Nonpharmacologic strategies for symptom management were described by 63.2% of the study participants for cataplexy, 54.5% for sleep attacks, and 35.5% for excessive daytime sleepiness. Specific management and coping strategies are provided.

Resolution of partial cataplexy in multiple sclerosis by treatment with weak electromagnetic fields

Cataplexy, an ancillary symptom of narcolepsy, involves the sudden loss of muscle tone without altered consciousness usually brought on by sudden excitement or emotional influence and extreme exertions (Guilleminault et al., 1974; Parks et al., 1974; Guilleminault, 1976; Aldrich, 1992; 1993; Scrima, 1981; Baker, 1985). Attacks of generalized cataplexy produce complete atonic, areflexic partial or complete paralysis of striated muscles commonly involving the leg muscles resulting in collapse of the knees and falling while milder forms often termed partial cataplexy may manifest by sagging of the face, eyelid, or jaw, dysarthria, blurred vision, drooping of the head, weakness of an arm or leg, buckling at the knees, or simply a momentary sensation of weakness that is imperceptible to observers (Guilleminault, 1976; Aldrich, 1993). The duration of cataplexy is usually a few seconds, although severe episodes can last several minutes and rarely several hours or days in the case of "status cataplecticus" (Parkes et al., 1974; Guilleminault, 1976; Billiard & Cadilhac, 1985; Aldrich, 1992; 1993). This report concerns a 51 year old man with chronic progressive multiple sclerosis who exhibited daily episodes of partial cataplexy which resolved within 3 weeks after he received treatment with picotesla electromagnetic fields.

[Niemann-Pick disease type C]

Niemann-Pick disease type C (NPC) is an autosomal recessive neurovisceral lipid storage disorder, but the basic defect has not yet been clarified. Diagnostic biochemical makers are intracellular accumulation of free cholesterol or the decreased esterification of exogenous cholesterol. The differences in the severity of defective esterification are related to the onset of the disease. Genetically, an abnormal gene is located on the human chromosome 18. Biochemically, many drugs, i.e. imipraine, progesterone and bafilomycin A1 are known to interfere with cholesterol esterification. Clinically, vertical supranuclear gaze palsy and cataplexy are specific symptoms. The filipin stain of the foamy cell in bone marrow is available for rapid diagnosis. Many therapies, i.e. dimethyl sulfoxide, low-cholesterol diet and transplantations, have been challenged but improvement of neurological symptoms have not been reported.

Symptomatic cataplexy in pontomedullary lesions

Cataplexy is a cardinal manifestation of the narcolepsy syndrome. Although symptomatic narcolepsy is well described, isolated cataplexy is extremely rare. We reviewed clinical and radiologic data in two patients with isolated symptomatic cataplexy and associated CNS disease. In an HLA-DR2-positive patient with chronic progressive MS, we confirmed cataplexy by observation of reported spells. MRI revealed diffuse white-matter lesions involving the medial medulla, pons, and subcortical white matter; protriptyline provided symptomatic relief. A second patient with a pontomedullary pilocytic astrocytoma developed infrequent but recurrent cataplectic attacks in association with sleep fragmentation due to nocturnal cough and nausea. MRI revealed an enhancing lesion involving the dorsal pons and medulla. Genetic predisposition and sleep fragmentation may precipitate symptomatic cataplexy in patients with structural pontomedullary lesions.

Further characterization of the alpha-1 receptor subtype involved in the control of cataplexy in canine narcolepsy

We have demonstrated previously that central noradrenergic mechanisms, especially postsynaptic alpha-1 receptors, are critically involved in the regulation of cataplexy, a pathological manifestation of rapid eye movement sleep atonia in narcolepsy. However, it has been shown recently that alpha-1 receptors constitute a heterogeneous population of binding sites, which is encoded by several distinct genes. In light of these findings, we investigated the possibility that the effect of alpha-1 compounds on cataplexy found in our previous study is mediated more specifically by certain alpha-1 receptor subtypes than by other subtypes. We therefore examined the effects of eight selective alpha-1 antagonists and five agonists on canine cataplexy and compared these with the affinities of the same compounds for the canine central alpha-1a and alpha-1b subtypes. The affinities of the compounds for the alpha-1 receptor subtypes were assessed by using [3H]prazosin receptor binding in combination with a 5-methylurapidil (an alpha-1a selective ligand) mask. Six of the eight alpha-1 antagonists tested exacerbated canine cataplexy, whereas all five agonists tested suppressed cataplexy. Furthermore, the potency (ED50 values) of the compounds on cataplexy significantly correlated with the affinity of the compounds for the alpha-1b binding site. These results are consistent with our earlier implication of the alpha-1 receptor mechanisms in the control of cataplexy and further suggest a specific involvement of the alpha-1b receptor subtype in these mechanisms.

Narcolepsy associated with primary temporal lobe B-cells lymphoma in a HLA DR2 negative subject

Narcolepsy and cataplexy began one year before treatment of a left mid-temporal primary B-cells lymphoma in a HLA DR2 negative man. Treatment with radio therapy and immunosuppression induced regression of the lymphoma and disappearance of narcolepsy and cataplexy.