Recognition and Management of Narcolepsy

Arch Dis Child 1999;81:519–524 519

CURRENT TOPIC Arch Dis Child: first published as 10.1136/adc.81.6.519 on 1 December 1999. Downloaded from

Recognition and management of narcolepsy

Gregory Stores

Perhaps as many as 5% of adults are excessively form of sleep: sleep attacks (sleep), cataplexy sleepy to a clinically relevant extent.1 The com- and sleep paralysis (atonia of the skeletal mus- parable figure for children is not known, but culature), hypnagogic and hypnopompic hallu- sleepiness is associated with many diVerent con- cinations (dreaming). In narcolepsy, these ditions and, although a neglected topic, it can be aspects become dissociated and intrude into the cause of serious psychological and social wakefulness. However, the physiopathogenesis disadvantage.2 Narcolepsy is by no means the of narcolepsy seems to be more complicated most common cause of excessive sleepiness. than this, with evidence of non-REM (NREM) Nonetheless, it is not the rarity once supposed, sleep and possibly circadian sleep wake rhythm and poses special problems of recognition and abnormalities. Basic neurochemical mecha- management, especially in young people. The nisms are not yet well defined.3 purpose of this article is mainly to review the There are ill understood associations be- clinical picture of narcolepsy in children and tween narcolepsy and obstructive sleep apnoea, adolescents, emphasising the need for paediatri- periodic limb movements in sleep, and REM cians, child psychiatrists, and others to take a sleep behaviour disorder. Genetic influences wide view of the ways in which the condition can are prominent in narcolepsy, but environmen- show itself. The clinical picture is often very dif- tal factors, such as stress or illness, also aVect ferent from that of the fully developed nar- the severity of symptoms. Narcolepsy is a colepsy syndrome in adults. It is, therefore, at lifelong illness. Medication is usually needed, particular risk of either being overlooked or mis- as well as other supportive measures, such as construed. advice on various aspects of living.

Narcolepsy in general Features of narcolepsy in young people Narcolepsy is a neurological disorder, the main In comparison with adult narcolepsy, the con- classic feature of which is excessive sleepiness dition in children has received little attention,

during the day, with recurrent episodes of irre- in spite of the fact that Yoss and Daly discussed http://adc.bmj.com/ sistible sleep (sleep attacks). In its fully the topic as long ago as 1960.4 Since then a developed form the “narcolepsy syndrome” number of limited accounts have been pub- also includes sudden loss of muscle tone in lished including some based on small series of response to strong emotion (cataplexy), vivid cases or individual patients5–15 and, in the past dream-like experiences before falling asleep few years, fuller accounts.16–22 Kavey23 and (hypnagogic hallucinations) or on waking Kashden and colleagues24 have written speciﬁ- (hypnopompic hallucinations), and episodes of cally about the psychosocial aspects of nar- inability to move after waking in the morning colepsy in children and adolescents. Although on October 1, 2021 by guest. Protected copyright. (sleep paralysis). Estimates for the occurrence these accounts (very likely aVected by referral of the non-sleepiness (“ancillary”) components bias) form the still limited research interest that of the syndrome are: cataplexy (all cases where has been taken in young people with nar- cataplexy is required for the diagnosis of colepsy, collectively, they probably provide a narcolepsy; however, others accept that in fairly balanced view, which needs to be about 20% of cases cataplexy is not present), conveyed to a wide range of clinicians. The fol- hypnagogic or hypnopompic hallucinations lowing is an outline of the picture that is (50–60%), and sleep paralysis (40%). These emerging. Further details are provided in the symptoms occur in various combinations and recent fuller descriptions just mentioned. less than half of those with narcolepsy develop all four of them. In narcolepsy, overnight sleep is generally disrupted, causing some degree of Prevalence persistent tiredness. Additional symptoms can This is uncertain partly because of variable University Section, include automatic behaviour (complicated be- diagnostic standards but, even so, the condition Park Hospital for haviour in a sleepy state with impairment of cannot be the rarity often supposed. The figure Children, Old Road, consciousness), poor memory and concentra- usually quoted for adult narcolepsy in the USA Headington, Oxford OX3 7LQ, UK tion, and visual disturbances such as blurred is 4–10/10 000 (the ﬁgure is much higher for G Stores vision and diplopia. Japan and much lower for Israel). Assuming Narcolepsy has been viewed as primarily a comparable rates in the USA and the UK, this Correspondence to: disorder of rapid eye movement (REM) sleep represents at least 250 000 Americans and Professor Stores 25 email: gregory.stores@ mechanisms. Each of the classic tetrad of about 20 000 cases in the UK. There is gen- psych.ox.ac.uk symptoms represents a main feature of this eral agreement that at least half the cases begin 520 Stores

in childhood although, as discussed shortly, the indicates a separate narcolepsy-like condition. Arch Dis Child: first published as 10.1136/adc.81.6.519 on 1 December 1999. Downloaded from condition is usually not diagnosed until much In most cases, however, this feature develops later, if correctly diagnosed at all. after excessive sleepiness has appeared (perhaps years later), bringing the child’s condition Age of onset to medical attention for the first time because it Perhaps curiously for a condition that often is perceived as more abnormal than sleepiness. appears to have a genetic and immunological Sometimes the two develop together and, in a basis, the reported age of onset of narcolepsy is minority, cataplexy is the initial symptom. In very wide, from early childhood to at least either case, like excessive sleepiness, cataplexy middle age. The youngest patient in the series can take various forms. At its most subtle, described by Guilleminault and Pelayo22 was weakness causes the child to feel strange or 2.1 years at the time of diagnosis. Peak age of unsteady without obvious external change. onset is about 14 years. Challamel and Otherwise, attacks may consist of slight observ- colleagues16 pooled the information from three able weakness of the limbs, face, head, and studies involving a total of 235 adult patients neck causing the knees to buckle, the head or with narcolepsy, and reported that 34% shoulders to drop, or the jaw to sag. Recogni- presented their first symptoms before the age of tion is made less diYcult when the child 15 years (a lower proportion than other authors suddenly drops to the ground and is unable to have claimed), 16% before 10 years, and 4.5% move perhaps for several minutes. Combina- before 5 years of age. tions of these various manifestations are not unusual. Important diagnostic features are that Presentation emotion (often laughter but also other positive A confident diagnosis of childhood narcolepsy as well as negative experiences, such as fear) is possible if excessive daytime sleepiness acts as a trigger, and that eye and respiratory (including sleep attacks) develops suddenly, movements are preserved even in the more combined with cataplexy, sleep paralysis, and dramatic forms. hypnagogic hallucinations, together with the abnormalities of sleep physiology characteristi- SLEEP PARALYSIS AND HYPNAGOGIC AND cally seen in adults—rapid onset of sleep and HYPNOPOMPIC HALLUCINATIONS the early appearance of REM sleep. However, These seem to be unusual in young patients this clear cut, classic picture seems to be un- but, when they occur (sometimes together) usual in the early stages of the disorder. The they can be very frightening. Very rarely they exact proportion of non-classic presentations is are the first symptom of the condition to not clear, but a number of ambiguous presen- appear. The dream-like and often vivid halluci- tations have been described, which have natory experiences are usually visual, but contributed to diagnostic confusion and delays tactile and auditory forms are also described. (sometimes for years), with repeated referrals Consciousness is preserved in these experi- to diVerent clinical services. ences and also during attacks of cataplexy.

EXCESSIVE SLEEPINESS OTHER ASSOCIATED TYPES OF SLEEP http://adc.bmj.com/ This is the predominant complaint in most cases DISTURBANCE but it can take various forms. The adult picture DiYculty getting to sleep because of a fear of of sleep attacks against a background of general night-time experiences has already been men- sleepiness (caused by disturbed overnight sleep) tioned. Frequent wakenings are also described, is seen in only the minority of prepubertal possibly associated with periodic limb move- patients. The ﬁrst sign of sleepiness may consist ments, although reports of the occurrence of of no more than wanting to sleep longer such movements in children with narcolepsy

overnight. However, individual diVerences in have been inconsistent. Night terrors and on October 1, 2021 by guest. Protected copyright. sleep requirements make it particularly diYcult frequent nightmares have been described in a to assess excessive sleepiness in very young chil- high proportion of cases. In contrast, automatic dren. Presumably, it is for this reason that behaviour (said to be very common in adults features other than sleepiness were the present- with narcolepsy) and sleep apnoea (also linked ing complaints in the children up to the age of 5 to narcolepsy in adults) do not feature in years in the series reported by Guilleminault and reported series of young patients. Pelayo.22 In a child of school age, a more obvious sign of sleepiness would be the persistence of SECONDARY PSYCHOLOGICAL EFFECTS regular daytime naps because these should nor- These are common and may well overshadow mally cease by the age of 3–4 years. An their causes and mistakenly lead to referral for important point emphasised by Dahl and psychiatric or educational advice. Understand- colleagues26 is that, especially in young children, ably, children often become fearful, embar- sleepiness can take the form of an increase rather rassed, and distressed in other ways (including than a reduction in activity, with the presence of feeling helpless) by the experiences that irritability, aggression, and attention deﬁcit narcolepsy imposes on them. They may deny hyperactivity disorder symptoms. or conceal the condition. Inappropriate reactions by parents, teachers, CATAPLEXY and other professionals (including physicians), Opinions diVer as to whether narcolepsy as well as peers, based on misinterpretation of should be diagnosed in the absence of the narcolepsy symptoms or the child’s reac- cataplexy and it remains something of an open tions to them, and restrictions placed on question whether the absence of cataplexy recreational and social activities, make a Recognition and management of narcolepsy 521

di cult situation worse. The problem is inten- Examples are given in the literature of how,

Y Arch Dis Child: first published as 10.1136/adc.81.6.519 on 1 December 1999. Downloaded from sified by inappropriate or delayed diagnosis as a consequence of failure to recognise not and treatment, which seem to be common- only the more subtle manifestations of nar- place. Even when correct treatment is given colepsy, but even the more classic features, this may itself cause further adverse eVects. misinterpretation, equivocation, referral to Additional problems may arise from poor psychological or educational services, or inap- school progress caused by the eVect of propriate medical investigations may extend sleepiness on concentration, memory, and over long periods, sometimes many years. In other aspects of cognitive function,27 and the many cases, the true nature of the child’s con- adverse psychological eVects of persistently dition only came to light because a sleep disrupted overnight sleep.28 It is no surprise disorders service was available for a further that in reported series of children with opinion. The shortage of such centres with a narcolepsy a range of serious psychological special interest in children is a problem, problems are consistently described, especially although a general improvement in awareness emotional lability, depression, diYcult or would help. aggressive behaviour, social withdrawal and isolation, and academic failure. Clinical implications (1) Child health professionals should be aware Misdiagnosis that narcolepsy in young children is not a The non-specific nature of the early features of rarity and that they need to be familiar with narcolepsy, combined with the very limited its clinical features in both its classic and awareness that the condition can start in these less obvious forms. ways, leads to various misinterpretations. (2) Narcolepsy should be suspected if a The fact that the onset of narcolepsy can be child’s excessive sleepiness cannot be triggered by emotional stress can itself be mis- explained in other ways. Very many child- leading. Psychiatric misdiagnosis features hood sleep disorders are now recognised, prominently in the published series including grouped (with some overlap) according to severe depression, conduct and oppositional the main presenting symptom: sleepless- defiant disorders, attention deficit hyperactivity ness, excessive daytime sleepiness, and disorder, conversion disorder (especially if episodic disturbances of behaviour associ- cataplexy is not recognised as such), and even ated with sleep (parasomnias).29 30 The psychotic states if hypnagogic hallucinations main cause of excessive sleepiness is are misconstrued. Medical misdiagnoses that insuYcient sleep for various reasons, have been reported include epilepsy and other including mistiming of the sleep phase or neurological or medical disorders capable of irregular sleep patterns, especially in ado- causing hypersomnia. lescence. Often, however, the problem Sometimes, a sleep disorder other than nar- results from disrupted overnight sleep, for colepsy has been considered initially, for exam- such reasons as obstructive sleep apnoea, ple terrifying hypnagogic hallucinations may be other medical disorders, and sometimes

labelled “night terrors”, or the child’s fear of frequent parasomnias. Narcolepsy is the http://adc.bmj.com/ bedtime because of such frightening experi- main example of disorders that are ences may be thought of as the more usual characterised by an intrinsic increase in childhood unwillingness to go to bed at the sleep requirements. Other members of this time preferred by parents. Problems getting up group are “idiopathic hypersomnia” in the morning may also be misinterpreted as (where overnight sleep is prolonged and “diYcult” behaviour, especially in adolescents very sound, with great diYculty getting up with narcolepsy. in the morning, but without any of the

Misinterpretation of narcolepsy symptoms is clinical or polysomnographic features of on October 1, 2021 by guest. Protected copyright. not confined to the medical profession. The the REM sleep abnormality seen in reported series indicate that teachers may well narcolepsy); and the Kleine-Levin syn- be critical of the child with narcolepsy because drome, in which classically long periods of of their perception of narcolepsy symptoms as excessive sleepiness (associated with laziness, poor motivation, or diYcult behav- overeating, hypersexuality, and other be- iour. Sometimes use of illicit drugs is sus- havioural abnormalities) alternate with pected. Alternatively, even able children with periods of normality. It is important not to narcolepsy may be considered in need of confuse sleepiness with weariness or special educational provision because of the fatigue (without an increased tendency to mistaken belief that they are intellectually lim- sleep) for which physical illness is a more ited. Such disapproval or misunderstanding likely explanation. It is also very relevant may persist even after the diagnosis of nar- that the ancillary symptoms of narcolepsy colepsy has been made, indicating the need for occur in the general population as isolated much better appreciation of the nature of the phenomena (frequently in the case of hal- condition. It is easy to see how such misjudg- lucinatory phenomena and sleep paraly- ments can cause escalating conflict between sis) without being part of the narcolepsy children, or their parents, and school. How- syndrome. ever, some parents themselves may have (3) As already explained, the early features of misgivings about their child’s symptoms, or the narcolepsy syndrome can be both sub- they might be unsympathetic to the child’s tle and non-specific with a wide differential understandable diYculties and reactions to the diagnosis including epilepsy, clumsiness, condition. psychiatric disorder, and the various 522 Stores

causes of excessive daytime sleepiness speciﬁcity is restricted. However, a nega- Arch Dis Child: first published as 10.1136/adc.81.6.519 on 1 December 1999. Downloaded from other than narcolepsy. The possible diY- tive result appears to make the diagnosis culty of recognising the condition should of narcolepsy unlikely, although patients not be underestimated, especially in young are described who are HLA DQB1 0602 children or, indeed, older ones where the negative and yet have the clinical and picture may have been obscured by PSG features of narcolepsy. A variety of psychological complications, which then diVerent conditions on the narcolepsy dominate the clinical picture. Particularly theme have been discussed by Parkes et careful scrutiny of both the present symp- al.33 toms and the past sequence of events is (6) As part of the initial diVerential diagnosis, required. Repeated clinical assessment basic haematological tests and endocrine may be needed before convincing features studies, together with electroencephalo- of the disorder come to light. graphy and urine drug screen, may be (4) Once there is suggestive evidence of appropriate, but further special investiga- narcolepsy, standardised physiological tions for narcolepsy itself have little part to sleep studies (polysomnography or PSG) play. At least, that is the usual view based are required for a deﬁnite diagnosis. These on the general impression that “sympto- should involve overnight PSG (partly to matic” narcolepsy is rare.34 Challamel and exclude other causes of excessive sleepi- her colleagues16 have described examples ness) combined with multiple sleep la- from the literature and their own experi- tency testing (MSLT), which is an objec- ence where childhood narcolepsy appears tive measure of daytime sleepiness (see to have been associated with such condi- Kotagal20 for further details of these tions as Niemann Pick disease type C, procedures). In general, it is thought that diencephalic tumour, Tourette syndrome, children with narcolepsy will show the Turner syndrome, thymoma, and preco- same abnormal features as adults—mainly cious puberty. The authors suggest that the they take an abnormally short time to fall possibility of symptomatic narcolepsy asleep when taking daytime naps (short should be seriously considered (and the sleep latency), and have a tendency to go appropriate investigations, such as neuro- straight into REM sleep (sleep onset REM imaging, performed) in pre-teenage chil- periods or SOREMPS). However, the dren with narcolepsy, especially when classic PSG criteria for the diagnosis of cataplexy is very prominent (including sta- adult narcolepsy might need to be relaxed tus cataplecticus), where classic PSG somewhat for use with children, some of evidence is absent (accepting that this whom might not display the adult charac- might be the case or early “idiopathic” teristics until later in the evolution of their narcolepsy), or where HLA typing is nega- condition. In particular, the mean sleep tive. It might be argued, however, that latency in children with narcolepsy may be some of the cases proposed as examples of less than seven to 10 minutes (rather than symptomatic narcolepsy, including some

five minutes for adults), and some chil- with Niemann Pick disease type C, should http://adc.bmj.com/ dren do not initially show the two or more not be classified as narcolepsy because they SOREMPS out of the five MSLT naps lack the characteristic clinical and PSG seen in adult patients. The high level of features of this condition.20 This issue is alertness during the day that is character- one of the aspects of childhood narcolepsy istic of older, prepubertal children may that needs further study, in addition to its oVset to some extent the excessive daytime characterisation compared with the better sleepiness seen in other patients with nar- known adult forms.

colepsy. Unfortunately, PSG is not readily on October 1, 2021 by guest. Protected copyright. available and referral to a special centre will often be necessary. Even there, it is Management important that these procedures are Detailed discussion of treatment and wider performed with an understanding of the aspects of care of children with narcolepsy has special considerations regarding children. been provided by Dahl,35 Kotagal,20 Brown and Home PSG including MSLT has been Billiard,36 and also Guilleminault and Pelayo,22 used with adults for the diagnosis of who are particularly mindful of the need to narcolepsy, and shows good agreement combine pharmacological approaches with with the results from laboratory attention to the psychosocial issues concerning recordings, except that fewer daytime the child, family, and school. Some of the main SOREMPS were seen in patients investi- points are as follows. gated at home.31 Recordings at home are (1) Early recognition and intervention are especially appropriate for children and highly desirable. Narcolepsy (especially the could be used more widely. Normative excessive sleepiness component) is lifelong data are now available at least for basic and therefore needs very long term care. PSG variables,32 although not as yet for However, the attention required is likely to MSLT. be much greater and more complicated if (5) Human leucocyte antigen (HLA) typing there have been long delays in diagnosis, is usually performed if narcolepsy is inappropriate treatments, and/or the accu- suspected, but its value is limited. mulation of the secondary psychosocial Although type DQB1 0602 in particular is and even psychiatric problems to which strongly associated with narcolepsy, its reference was made earlier. Recognition and management of narcolepsy 523

(2) The main specific aspect of care is Some families of aVected children find + Arch Dis Child: first published as 10.1136/adc.81.6.519 on 1 December 1999. Downloaded from medication, which is best reserved for chil- mutual support groups very helpful. dren whose lives are being greatly aVected Narcolepsy is a complicated condition re- by their narcolepsy. Methylphenidate and quiring long term comprehensive care. General pemoline have often been prescribed. The paediatricians and child psychiatrists in par- main side eVects of such stimulant drugs ticular need to be mindful of the ways that it are headaches; features of overarousal such can present. As is true of the more complicated as agitation, tension, and anxiety; and forms of epilepsy, management of narcolepsy gastrointestinal upset. Breaks from taking needs special interdisciplinary provision to be drugs at weekends and during holidays are eVective and to prevent the potentially very important to avoid the development of tol- serious developmental consequences of the erance. Dosage needs to keep pace with condition. physical growth. Modafinil is a recent addition, licensed in the UK for use with 1 Billiard M, Alperovitch A, Perot C, Jammes A. Excessive patients age 12 years and above. It is unre- daytime somnolence in young men: prevalence and lated to other central nervous system contributing factors. Sleep 1987;10:297–305. stimulant drugs and is said to have fewer 2 Anders TF, Carskadon MA, Dement WC, Harvey K. Sleep habits of children and the identification of pathologically adverse psychological eVects, including sleepy children. Child Psychiatry Hum Dev 1978;9: less risk of abuse compared with tra- 56–63. 37 3 Broughton R J. Narcolepsy. In: Thorpy MJ, ed. Handbook of ditional treatments. Tricyclic drugs, such sleep disorders. New York: Marcell Dekker, 1990:197–216. as clomipramine, has been the main treat- 4 Yoss RE, Daly DD. Narcolepsy in children. Pediatrics 1960; 25:1025–30. ment for cataplexy (and also hallucinations 5 Navelet Y, Anders T, Guilleminault C. Narcolepsy in and sleep paralysis). Their main side children. In: Guilleminault C, Dement W,Passouant P, eds. Narcolepsy. New York: Spectrum, 1976:171–7. eVects are dry mouth, constipation, and 6 Wittig R, Zorick F, Roehrs T, Sicklesteel J, Roth T. urinary retention. Selective serotonin re- Narcolepsy in a 7 year old child. J Pediatr 1983;102: 725–7. uptake inhibitors, such as fluoxitine, are a 7 Chisholm RC, Brook CJ, Harrison GF, Lyon L, Zukaitis D. recently introduced alternative. The use of Prepubescent narcolepsy in a six year old girl [abstract]. Sleep Research 1985;15:113. tricyclic drugs and selective serotonin 8 Lenn NJ. HLA-DR2 in childhood narcolepsy. Pediatr Neurol reuptake inhibitors has not been studied 1986;2:314–15. 9 Young D, Zorick F, Wittig R, Roehrs T, Roth T. Narcolepsy systematically in young patients with nar- in a pediatric population. Am J Dis Child 1988;142:210–13. colepsy. Clomipramine is oYcially licensed 10 Kotagal S, Hartse KM, Walsh JK. Characteristics of narcolepsy in preteenaged children. Pediatrics 1990;85: for patients 12 years or older; fluoxitine for 205–9. those age 18 and above. Preliminary 11 Georges CFP, Singh SM. Juvenile onset narcolepsy in an individual with Turner syndrome. A case report. Sleep attempts to improve the quality of sleep by 1991;14:267–9. means of benzodiazepine medication in 12 Cohen FL, Nehring, WM, Smith KM, et al. Adolescents adults with very disrupted overnight sleep with narcolepsy: a comparison with other chronic disorders and controls. Preliminary findings [abstract]. Sleep Research have not produced improvements in day- 1991;20:229. 13 Allsopp MR, Zaiwalla Z. Narcolepsy. Arch Dis Child time sleepiness. Unfortunately, non- 1992;67:302–6. compliance with recommended medi- 14 Walsleben JA, Rapoport DM. Narcolepsy in young children [abstract]. Sleep Research 1993;22:285.

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Think fuzzy and solve Fuzzy logic could well be a description of what goes on in many a doctor’s brain when the telephone rings at three in the morning but, more formally, it is a mathematical system introduced in 1965 which deals with impreci- sion, uncertainty, and partial truth. Since all of these attributes are part of the staple fare of medical practice most doctors would no doubt want to buy into such a system. In Saõ Paulo, Brazil it was used to arrive at a successful measles mass vaccination strategy when they had a limited number of doses of vaccine available (Eduardo Massad and colleagues. International Journal of Epidemiology 1999;28:550–7). The fuzzy logic system of decision making requires a set of goals, a set of possible actions, and a set of constraints, from which a decision can be made about the action that best satisfies the goals and constraints. The team in Brazil were faced with a rise in measles notifications despite a previously successful vaccination programme. They took as their goal the control of measles in children under 14 and considered 8 possible vaccination strategies. They obtained a series of constraints from an expert medical panel. Using fuzzy logic one strategy was chosen: selective vaccination of children aged 9 months to 6 years at fixed sites in the primary care network. The strategy proved successful in Saõ Paulo city but a second mass vaccination campaign in the interior of the state was necessary 2 months later. ARCHIVIST http://adc.bmj.com/ on October 1, 2021 by guest. Protected copyright.