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 (per- haps 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.