Narcolepsy

Tobacco addiction and the dysregulation of brain stress systems

Tobacco is a highly addictive drug and is one of the most widely abused drugs in the world. The first part of this review explores the role of stressors and stress-associated psychiatric disorders in the initiation of smoking, the maintenance of smoking, and relapse after a period of abstinence. The reviewed studies indicate that stressors facilitate the initiation of smoking, decrease the motivation to quit, and increase the risk for relapse. Furthermore, people with depression or an anxiety disorder are more likely to smoke than people without these disorders. The second part of this review describes animal studies that investigated the role of brain stress systems in nicotine addiction. These studies indicate that corticotropin-releasing factor, Neuropeptide Y, the hypocretins, and norepinephrine play a pivotal role in nicotine addiction. In conclusion, the reviewed studies indicate that smoking briefly decreases subjective stress levels but also leads to a further dysregulation of brain stress systems. Drugs that decrease the activity of brain stress systems may diminish nicotine withdrawal and improve smoking cessation rates.

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.

Benefits and risks of pharmacotherapy for narcolepsy

Narcolepsy is a life-long central nervous system (CNS) syndrome characterised by excessive sleepiness, cataplexy, sleep paralysis, hypnagogic hallucinations and disturbed night-time sleep. Unsuccessfully treated narcolepsy confers increased risks on patients and on society due to the patient's increased chance of becoming involved in vehicle crashes and workplace mishaps. The syndrome may be diagnosed by a clinical history positive for cataplexy and excessive daytime sleepiness and negative for other more common sleep disorders such as sleep apnoea and sleep deprivation. Night-time polysomnography and multiple sleep latency testing are helpful in differentiating narcolepsy from other sleep problems. Recent data from canine, murine, and human forms of narcolepsy indicate that genetically or developmentally mediated deficits in the hypocretin neurotransmitter system may cause some, but not all, forms of narcolepsy. Pharmacotherapy for narcolepsy is required to control symptoms and involves the use of CNS stimulants or modafinil to control sleepiness and antidepressant medications or sodium oxybate to control cataplexy. Modafinil and sodium oxybate have been developed and approved specifically for the indication of narcolepsy based on large, double-blind, placebo-controlled, parallel group efficacy and safety studies. The efficacy of drugs in the treatment of narcolepsy is variable from patient to patient and usually associated with adverse effects that can limit patient compliance and, therefore, symptom control. Nevertheless, the benefits of pharmacotherapy are judged to outweigh the risks to the patient. The favourable benefit-risk ratio of pharmacotherapy is greater if one considers the reduced risk to society of vehicle crashes and workplace mishaps that might be precipitated by attentional lapses or sleep attacks in the untreated or under-treated patient with narcolepsy.

Sleep inertia

Sleep inertia is a transitional state of lowered arousal occurring immediately after awakening from sleep and producing a temporary decrement in subsequent performance. Many factors are involved in the characteristics of sleep inertia. The duration of prior sleep can influence the severity of subsequent sleep inertia. Although most studies have focused on sleep inertia after short naps, its effects can be shown after a normal 8-h sleep period. One of the most critical factors is the sleep stage prior to awakening. Abrupt awakening during a slow wave sleep (SWS) episode produces more sleep inertia than awakening in stage 1 or 2, REM sleep being intermediate. Therefore, prior sleep deprivation usually enhances sleep inertia since it increases SWS. There is no direct evidence that sleep inertia exhibits a circadian rhythm. However, it seems that sleep inertia is more intense when awakening occurs near the trough of the core body temperature as compared to its circadian peak. A more controversial issue concerns the time course of sleep inertia. Depending on the studies, it can last from 1 min to 4 h. However, in the absence of major sleep deprivation, the duration of sleep inertia rarely exceeds 30 min. But all these results should be analysed as a function of type of task and dependent variables. Different cognitive functions are probably not sensitive to the same degree to sleep inertia and special attention should be provided to dependent variables as a result of the cognitive processes under review. Finally, sleep disorders represent risk factors which deserve new insight in treatment strategies to counteract the adverse effects of sleep inertia.

Methylphenidate and brain dopamine neurotoxicity

To further evaluate the dopamine (DA) neurotoxic potential of the widely prescribed psychostimulant, methylphenidate, mice were treated with various doses (range: 10-120 mg/kg) and treatment schedules of methylphenidate (every 2 h x 4 or twice daily x 4). Higher doses of methylphenidate produced intense stereotypy, as well as short- (5-day), but not long- (2-week), term depletions of striatal DA axonal markers. By contrast, amphetamine caused not only intense stereotypy, but also profound, long-lasting, dose-related DA deficits. These findings indicate that results of studies of amphetamine neurotoxicity using short (5-day) post-drug survival periods are potentially misleading. Further, the present findings confirm and extend previous results indicating that methylphenidate, unlike amphetamine, lacks DA neurotoxic potential, and strongly suggest that DA efflux, although perhaps necessary, is not sufficient for the expression of amphetamine-induced DA neurotoxicity.

The pedunculopontine nucleus--auditory input, arousal and pathophysiology

This review describes the role of the pedunculopontine nucleus (PPN) in various functions, including sleep-wake mechanisms, arousal, locomotion and in several pathological conditions. Special emphasis is placed on the auditory input to the PPN and the possible role of this nucleus in the manifestation of the P1 middle latency auditory evoked response. The importance of these considerations is evident because the PPN is part of the cholinergic arm of the reticular activating system. As such, the auditory input to this region may modulate the level of arousal of the CNS and, consequently, abnormalities in the processing of this input can be expected to have serious consequences on the level of excitability of the CNS. The involvement of the PPN in such disorders as schizophrenia, anxiety disorder and narcolepsy is discussed.

Effects of zopiclone on sleep and symptoms in schizophrenia: comparison with benzodiazepine hypnotics

Sleep variables and psychiatric symptoms were investigated in 6 male chronic schizophrenic outpatients. The patients were being treated with benzodiazepine (BZD) hypnotics for more than 8 weeks, and BZDs were replaced with zopiclone (ZPC) 15 mg/day. Polysomnographic examinations, subjective sleep assessments and BPRS scoring were performed during BZD therapy and at the end of 8 weeks of ZPC therapy. The doses of neuroleptics and anticholinergic agents remained fixed throughout the study. The amount of slow-wave sleep (SWS) was markedly small and that of stage 1 sleep was moderately large during BZD therapy. The amount of stage 1 was smaller and that of stage 2 was larger during treatment with ZPC than BZDs. There were no significant change in the amount of SWS between the treatment. Half of the patients exhibited a sleep-onset REM period (SOREMP) during ZPC therapy. Both total BPRS score and negative symptom score were lower during treatment with ZPC than BZDs. These results suggest that ZPC may be more beneficial in treating schizophrenic insomnia than BZD hypnotics and that reduced SWS and SOREMP may be partly involved in the pathophysiology of schizophrenia.

Sleep-disordered breathing and behavior in three risk groups: preliminary findings from parental reports

Sleep-related breathing disorders may cause excessive daytime sleepiness, cognitive impairment, and behavior problems in children and adolescents. Adenotonsillar enlargement (AT) is known to be a significant risk factor for these disorders, which have also been reported in several patients with Down syndrome (DS). Children with attention deficit disorder/hyperactivity (ADD) show behavior problems that may be related to disturbed nocturnal sleep in some. To evaluate the relationships among these disorders and symptoms, parents of 29 school-aged children with AT, 70 with DS and 48 of their siblings (DS-SIB), and 21 with ADD completed a 20-item screening questionnaire covering nocturnal sleep symptoms and daytime behavior problems. Nocturnal symptoms of sleep-related breathing disorders--snoring, breathing pauses during sleep--were reported more commonly by parents of AT and DS children. However, parents of two of the ADD children reported significant signs of sleep-related breathing disorders. Daytime behavior problems were more common in ADD and AT than in the DS group. Bedwetting reports did not distinguish groups. Direct comparisons of DS and DS-SIB groups showed that more DS were mouth breathers, snored, stopped breathing at night, and were sleepy in the daytime. These findings underscore the importance of obtaining a history of nocturnal sleep from parents of children with AT and DS, as well as those with disrupted daytime behavior.

Conversion disorder revisited: severe parasomnia discovered

In light of recently described and reviewed disorders of movement and behaviour during sleep, the long standing diagnosis of conversion disorder in a forty-nine year old Vietnam veteran was reappraised. Polysomnographic studies showed that the nocturnal component of his "pseudoseizures" was due to physical disorder, a severe mixed parasomnia comprising the recently described REM behaviour disorder and a non-REM parasomnia. His sleep architecture was also deranged, featuring reduced REM latency and increased REM density. An association between these abnormalities and psychological trauma is recognised in the literature. Treatment with clonazepam has abolished the nocturnal behavioural disturbance. His daytime pseudoseizures occur less frequently and his general well being is improved. The case is a reminder that physical disorder may underlie and act as prototype to the psychologically-driven symptom. Before attributing behavioural disturbance at night to psychological causes alone, polysomnographic studies should be done to exclude a treatable parasomnia.

Migraine visual auras. A medical update for the psychiatrist

Auras of visual aberrations as well as other neurological disturbances including somatosensory and perceptual symptoms that precede a headache distinguish migraine with aura (classic migraine) from migraine without an aura (common migraine) and other varieties of headache. Visual auras that characterize migraine with aura can be classified and distinguished from other neurologic and psychiatric causes of visual aberrations. Examples of migraine visual auras, which are often described but rarely shown in the medical literature, are presented and their mechanism is discussed.

Auditory evoked potentials in narcolepsy and sleep terrors

Dysfunction of brainstem reticular activating centers has been suggested in some sleep disorders, including narcolepsy and sleep terrors. Previous studies have suggested normal brainstem auditory evoked potentials (BAEPs) in narcolepsy and enhancement of long-latency auditory event-related potentials (ERPs) in sleep deprivation and conditions of pathological somnolence. Sleep terrors have not to date been studied neurophysiologically. We recorded early latency BAEPs and long-latency auditory ERPs in 8 patients with narcolepsy and 5 individuals with sleep terrors, and compared them to 10 normal controls. Narcolepsy patients and controls did not differ significantly in absolute or interpeak latency of BAEPs. Sleep terror patients had significant prolongation relative to controls of III-V and I-V interpeak latencies. The N1, N2, and P3 AEP components were prolonged in latency in narcoleptic patients as compared to controls, while sleep terror patients did not differ from controls. No significant differences in amplitude were found. These findings suggest that a disturbance of integration of brainstem centers subserving wakefulness and sleep may play a role in the disordered arousal of sleep terrors, but suggest no specific abnormality in brainstem function in narcolepsy. The AEP changes in narcolepsy may be a manifestation of pathological sleepiness.

REM sleep suppression by monoamine reuptake blockade: development of tolerance with repeated drug administration

Drugs that block monoamine reuptake initially suppress rapid eye movement (REM) sleep in the cat and other species. Less is known about the effects of repeated drugs administration. Desipramine (DMI) and sertraline [1S,4S-N-methyl-4-(3,4-dichlorophenyl)-1,2,3,4-tetrahydro-1 -naphthylamine] (SER), which are relatively specific in blocking norepinephrine and serotonin reuptake, respectively, were each given to cats for approximately two and a half weeks. Six-hour sleep polygraphic records were obtained under the placebo condition, after acute drug administration, and again during chronic drug administration. DMI and SER both reduced REM sleep percentage acutely and in each case. Significant tolerance then developed. These actions of DMI and SER reflected changes in mean REM sleep episode duration as well as REM sleep episode number. Such differential effects of acute and chronic monoamine reuptake blockade on REM sleep behavior in the cat may ultimately be correlated with pharmacological changes at the receptor level.

Narcolepsy update

Narcolepsy, a disorder of excessive daytime sleepiness that affects more than 125,000 people in the United States, is technically defined as a daytime mean sleep latency (time elapsed before falling asleep) of less than 5 minutes in conjunction with verification of rapid eye movement sleep in at least two of five daytime nap periods. Cataplexy, hypnagogic hallucinations, and sleep paralysis are frequently associated with narcolepsy. Currently, overnight polysomnography and multiple sleep latency testing in a sleep disorders laboratory are used to diagnose narcolepsy. Standard pharmacologic therapy consists of the judicious use of stimulants to improve alertness and the administration of tricyclic and other antidepressant drugs to suppress cataplexy. In addition, good sleep hygiene (a regular sleep-wake schedule, an adequate amount of sleep at night, and scheduled daytime naps) is essential for optimal management of this disorder. Patient and family education about narcolepsy and its treatment is also important. Even with use of the best available treatment regimens, many patients with narcolepsy have substantial vocational and social impairments.

Compound narcolepsy: sleep pattern and involution

A review of studies of sleep in three-month-old infants, narcoleptics, and normal adults indicates that the sleep pattern in compound narcolepsy is in many ways involuted. Similarities in sleep onsets, REM-specific movement, REM dissociation, ambiguous sleep, nocturnal arousals, diurnal sleep-wake cycles, and relatively limited quiet-awake time are discussed as part of a global inability to inhibit state changes common to both infants and compound narcoleptics. The analogy with infant sleep patterns and results of studies of brain function in narcoleptics suggest that forebrain inhibitory processes are more important in narcoleptic symptomology than is brainstem dysfunction. Puberty and old age are critical periods for the development or exacerbation of the involuted sleep pattern. Closer study of the early development of narcoleptics and of lability of state changes in narcolepsy may aid in diagnosis and prognosis for susceptible individuals.

Compound narcolepsy: development of biochemical imbalance

In a review of existing literature, compound narcolepsy is shown to involve not only problems of sleep regulation, but also autonomic, hormonal, emotional, and possibly motor and cognitive dysfunctions, strongly implicating the hypothalamus, limbic system, and possibly the striatum and cortex in the disorder. Neurochemical studies and the pattern of narcoleptic symptoms support the idea of a dynamic imbalance between dopamine and acetylcholine in the etiology of the disorder. What is known about the natural history of compound narcolepsy suggests a developmental course beginning with fluctuations in dopamine release, followed by supersensitivity of dopamine autoreceptors, and later followed by a pattern of intrinsic oscillations and reciprocal "overshoots" in release of dopamine and acetylcholine to account for the typical sequence of appearance of narcoleptic symptoms.

Narcolepsy: a review of a common, life-long sleep disorder

Narcolepsy is a severe debilitating chronic life-long sleep disorder that can be ameliorated but not cured. In the United States, its prevalence is at least 1 in 1000 making it more common than multiple sclerosis or Parkinson's disease. Its symptoms lead to severe lifestyle consequences, with profound impact on the affected persons, their interpersonal relationships, job, school experiences, and family life. Despite this, little has appeared in the nursing literature about the disorder. The most characteristic symptoms include uncontrollable excess daytime sleepiness, cataplexy (bilateral voluntary muscle weakness), sleep paralysis, hypnagogic hallucinations and disturbed night-time sleep. Characteristics of normal sleep are reviewed and compared with disturbances seen in narcolepsy. The aetiology, assessment, diagnosis, pharmacologic therapy, non-pharmacologic therapy and psychosocial issues are discussed along with needed research directions.

The functions and dysfunctions of laughter

Laughter is not usually included in the curriculum of medical schools, therefore it is often neglected by physicians. Laughter is a reflex located in the reticular system of the hindbrain. Rich connections explain its complexity. Laughter appears very early in life and each individual has a very characteristic and stable laughing style. Laughter and speech differentiate human beings from the animal kingdom. Laughter is a unique communication media, common to all human societies speaking different languages. Laughter has a mood elevating and relaxing effect. Laughter dysfunction consists of inappropriate response to the meaning or to the stimulus intensity. In the present study, laughter's dysfunction and disorders are presented. The purpose of this study was to extricate laughter from the diffuse obscurity of information into a new area of interest for scientific research.

Complex event-related potentials (P300 and CNV) and MSLT in the assessment of excessive daytime sleepiness in narcolepsy-cataplexy

The P300 and contingent negative variation (CNV) evoked potential (EP) paradigms were performed by 12 untreated narcoleptics and controls immediately prior to each nap of the Multiple Sleep Latency Test (MSLT) in order to assess whether they might hold promise as rapid quantitative techniques to assess excessive daytime sleepiness. The Stanford Sleepiness Scale (SSS) was also completed across test days and immediately before and after both the evoked potential recordings and MSLT naps. MSLT findings confirmed shorter sleep latencies and frequent SOREMPs in narcoleptics and a strong mid-afternoon increase in sleepiness based upon pressure for NREM sleep in both groups. On SSS narcoleptics were sleepier and they showed greater increase in sleepiness induced by the EP tests and greater sleepiness reduction by the MSLT naps. In the P300 paradigm, narcoleptics showed smaller component P3 amplitudes and larger P1 amplitudes. In the CNV paradigm, N1 latencies were greater in narcoleptics to both S1 and S2 and the post-CNV negative component was larger: but no significant differences were seen for the main CNV measures of negativity amplitude in the first or second halves of the response. The P300 paradigm but not the CNV, therefore, appeared to be a sensitive EP measure of sleepiness. Finally, EP components in both the P300 and CNV paradigms showed time-of-day (circadian) differences between narcoleptics and controls.

Evaluation of sleep disorders

This review summarizes the current approach to the diagnosis and treatment of sleep disorders. Classification of sleep disorders, basic sleep physiology, use of the sleep laboratory, and management of patients are discussed.

Multiple organ failure resulting from intravenous abuse of methylphenidate hydrochloride

A 32-year-old woman who abused methylphenidate hydrochloride developed complications including hepatic, renal, pancreatic, pulmonary, and CNS toxicities. These were manifested by abnormal liver function enzymes, poor urine output, hypotension, tachypnea, tachycardia, abnormal blood gases, rising serum BUN and creatinine, and hyperactive deep-tendon reflexes. All were reversible with medication withdrawal and supportive therapy. Toxicities of this medication and their implications are discussed.

The neurobiology of the narcoleptic syndrome

Relevant electroencephalographic, psychopharmacologic, and genetic research reports are described in support of a neurobiological explanation of the narcoleptic syndrome. Despite increased support in this realm, no single neurobiological theory has won unanimous approval among sleep researchers, which has led toward speculation that the condition may be heterogeneous in nature. A multifactorial perspective, including psychological as well as neurobiological influences, appears to be the most productive model for research. Future investigation of sleep disorders utilizing such a model may enhance the understanding of neurobiological correlates of behavioural disorders.

Penile tumescence in temporally normal and pathologic rapid eye movement sleep

The present study was conducted to determine whether the usual temporal relationship between rapid eye movement and penile tumescence was present in a group of narcoleptic patients who had demonstrated the abnormal phenomenon of sleep onset rapid eye movement. We studied 5 men with a clinical history of sleep attacks and at least 1 auxiliary symptom of narcolepsy. Results indicated that penile tumescence occurred during temporally normal and abnormal rapid eye movement sleep. These findings provide further evidence of the strong temporal relationship between rapid eye movement sleep and penile tumescence.

Methylphenidate decreases local glucose metabolism in the motor cortex

The local cerebral metabolism on glucose (l-CMRg) was evaluated in animals given methylphenidate (15 mg/kg) in order to investigate possible mechanisms of action of the drug. Significant increases in l-CMRg (p greater than 0.05) were found in the globus pallidus, entopeduncular nucleus, substantia nigra, subthalamic nucleus, inferior olive, red nucleus, lateral cerebellar cortex, ventral lateral nucleus of the thalamus and the midbrain reticular formation. Significant decreases (p greater than 0.05) in l-CMRg were found in the motor cortex. These results suggest possible mechanisms for methylphenidate's action in attention deficit disorders.

Insomnia and other sleep disorders

In treating the symptomatology of patients who are chronically ill, it is likely that the physician will encounter a significant number of patients who have sleep disorders. This article has described an approach for the assessment, differential diagnosis, and clinical management of the most prevalent sleep disorders, which are often chronic in nature and have significant psychosocial or medical consequences for the patient and his or her family. We have emphasized the importance for the physician to complement his general medical and diagnostic skills by taking a careful sleep history from the patient (and, in some instances from the bed partner or caretakers). There is no justification for the physician to routinely request costly sleep laboratory hypnopolygraphic evaluations to screen patients with sleep disorders. However, in those instances where the sleep history is highly suggestive of sleep apnea, a sleep laboratory evaluation is indicated. By incorporating the use of the sleep history in the general evaluation of patients with sleep disorders, the physician is better able to develop rational pharmacologic and non-pharmacologic approaches to managing these patients, including the judicious use of medication as an adjunctive treatment.

The pupil dark response in narcolepsy

The pupil dark response and maintenance of pupil area in darkness were compared in seven narcoleptic patients and 14 age-matched normal volunteers. Onset and degree of miosis after maximal pupil dilation in darkness were similar in the two groups, although three narcoleptic patients and no normal volunteers fell asleep during the experiment. The results of this study contradict earlier suggestions that pupillography can be used to distinguish normal individuals in family studies of narcoleptic patients.

Life effects of narcolepsy in 180 patients from North America, Asia and Europe compared to matched controls

A questionnaire survey has been made of the life effects of narcolepsy in 180 patients, 60 each from North American, Asian and European populations, with 180 similarly distributed age and sex matched controls. Life-effects were attributed by the patients to the primary symptoms of excessive daytime drowsiness, sleep attacks, cataplexy, vivid hypnagogic hallucinations and sleep paralysis, and also to other frequent symptoms such as visual problems (blurring, diplopia) and memory impairment. Occupational problems were prevalent (over 75%) and included statistically significant deleterious effects upon performance, promotion, earning capacity, fear of or actual job loss and increased disability insurance. Driving was greatly affected and patients fell asleep at the wheel more frequently (66%), had near or actual accidents from drowsiness or falling asleep at the wheel (67%), and could experience cataplexy (29%) or sleep paralysis (12%) while driving. Work or home accidents attributed to sleepiness or sleep (49%) or related to smoking (49%) were much more common in patients. There were also deleterious effects on education, recreation and personality related to disease. Narcolepsy can produce a variety of life-effects probably more serious and pervasive than, for instance, those of epilepsy, therefore emphasizing the importance of early diagnosis and treatment.

Myxedema and obstructive sleep apnea

Three cases of hypersomnolence, snoring and documented sleep apnea are reported. All three patients were profoundly myxedematous, both clinically and biochemically. Polygraphic studies during sleep documented the presence of repetitive episodes of obstructive sleep apnea in all three patients. These were accompanied by arterial oxygen desaturation. After becoming euthyroid following the administration of the l-thyroxine all patients underwent a repeat evaluation in the sleep laboratory. These studies revealed nearly complete resolution of obstructive sleep apnea in all patients. In addition, several sleep parameters showed marked improvement. These data strongly suggest that the presence of profound daytime sleepiness in hypothyroid patients could be indicative of a potentially lethal complication of myxedema, obstructive sleep apnea.

[Sodium gamma-hydroxybutyrate in the treatment of essential hypersomnia]

Five non-narcoleptic hypersomniac patients were given GHB (3.10 to 4.5 g per os) at night. Four patients reported a persistent improvement of their daytime sleepiness as a result of this treatment. Nocturnal polygraphic recordings were performed in all patients before and after GHB. The durations of sleep and of waking times were reduced after GHB while there was an increase of stages 3 and 4 during the first third of the night. It is possible that the increase in delta wave sleep early in the night is responsible for a re-establishment of a normal distribution of subsequent sleep stages and thus produces a more recuperative sleep.

The treatment of narcolepsy and cataplexy

Narcolepsy may affect as many as 250,000 Americans. It involves a neurologic defect in the regulation of sleep and wakefulness. The chief symptoms are sleepiness, inappropriate sleep episodes, and cataplexy. Narcoleptic patients also frequently complain of hypnagogic hallucinations, sleep paralysis, and automatic behavior, as well as disturbed nocturnal sleep. Narcolepsy usually develops in adolescence and is a life-long illness. Satisfactory treatment is not available at the present time. The current treatments of choice include general measures (such as patient and family counseling and frequent napping) and drug treatments, including methylphenidate for sleepiness and sleep episodes and imipramine for cataplexy. Medication dosages mut be adjusted for individual patients. Pharmacists have a special responsibility to monitor narcoleptic patients by becoming familiar with the disease and its symptoms and by encouraging patients to follow their drug regimens and to take drug holidays under the supervision of the physician when the drug dose becomes excessive.

Comparison of interwave latencies of brain stem auditory evoked responses in narcoleptics, primary insomniacs and normal controls

A study of brain stem auditory evoked responses (BAER) was carried out in 10 narcoleptics, 10 primary insomniacs and 10 normal controls to determine if a neurophysiologic abnormality could be detected in these primary sleep disorders. The mean interpeak conduction times of Wave I-III, III-V and Iv were compared between the following groups: normal controls awake and in monitored sleep; narcoleptics awake and in monitored sleep, normal controls awake and narcoleptics awake; normal controls awake and insomniacs awake; narcoleptics awake and insomniacs awake; narcoleptics with cataplexy (n = 6) awake and narcoleptics without cataplexy (n = 4) awake. No significant differences were found which suggests that these sleep disorders represent dysfunctions which do not involve brain stem structures subserving the BAER.

The treatment of narcolepsy-cataplexy with nocturnal gamma-hydroxybutyrate

Sixteen patients with narcolepsy and cataplexy were treated with gamma-hydroxybutyrate (GHB) given at night and tailored to achieve as continuous a night's sleep as possible. The dosage usually consisted of 1.5-2.25 gm orally at bedtime and then one or two further 1.0-1.5 gm doses with awakenings during the night, and totaled about 50 mg/kg. Apart from one patient who took only the bedtime dose, the subjective quality of night sleep improved in all patients and the number of irresistible daytime attacks of sleep and cataplexy substantially diminished. Some residual daytime drowsiness remained and this usually responded well to low doses of methylphenidate. Improvement has been maintained for up to 20 months without the development of tolerance. Two patients experienced adverse side effects necessitating withdrawal of GHB treatment, but no serious toxic effects have occurred.

Narcolepsy with tinnitus aura: interpretation

A fifty-five year old man was admitted to our ward for evaluation of narcoleptic-cataplectic attacks which were signaled by a "hissing sound like high pressure steam leaking out of a pipe." This tinnitus was exclusively localized to the right ear. It started about sixty-to-ninety seconds before the cataplectic episode (affecting mostly the jaw muscles) and lasted through part of it as it became progressively louder toward the end and ceased abruptly. It is postulated that, along with the collapse of tonic musculature of the mandible, a decrease of proprioceptive tone also affected the tensor tympani muscle leaving the middle ear vulnerable to internally generated noise. We further postulate that tinnitus was finally arrested by the generation of phasic bursts of contraction of the tensor tympani and/or the stapedius muscle at a later stage of cataplexy.

Effects of imipramine, chlorimipramine, and fluoxetine on cataplexy in dogs

Four narcoleptic dogs with cataplexy were given trials with the serotonin uptake blockers imipramine and chlorimipramine (known to be effective in treating cataplexy in humans). An even more selective serotonin uptake blocker, fluoxetine, was also tested. Injections of placebo, test compound, and placebo were given respectively on 3 successive days. Anticataplectic effects were measured approximately 30 min, 3 hr, and 6 hr postinjection by recording elapsed time and number of cataplectic episodes during the dogs' attempts to eat ten pieces of a desired food presented in a standard fashion. Imipramine (1 mg/kg) and fluoxetine (1.5 and 3.0 mg/kg)significantly improved performance, while chlorimipramine (0.5-5 mg/kg) had no clear effect. Data were not totally consistent with the notion that serotonin uptake blockers improve cataplexy in dogs, since chlorimipramine was not effective in these animals.