ANNOTATION
The More Unusual Sleep Disturbances of Childhood Neil Gordon, MD
The sleep patterns of children often cause anxiety to their parents. Some disturbances are unusual, and therefore may cause diagnostic difficulties. Sleep walking and night te"ors can be confused with epileptic seizures. The sudden sleep of narcolepsy can lead to false accusations, when in fact the episodes are beyond the child's control. The associated phenomena of cataplexy, hypnogogic hallucinations and sleep paralysis can be particularly alarming, especially if they occur in the absence of narcolepsy. The overlap between narcolepsy and the Kleine-Levin syndrome is confirmed. Although of a different nature the sleep apnoea syndrome is equally important from the point of view of diagnosis and treatment. Key words: Sleep disorders, night walking, narcolepsy, cataplexy, hypnogogic hallucinations, Kleine-Levin syndrome. Gordon N The more unusual sleep disturbances of childhood. Brain Dev 1992; 14:182-4
Parents are often anxious about their child's sleeping habits; whether they take a long time to get to sleep, wake often in the night, or wake early. Good common sense advice should of course be given [1,2]; and this almost always solves the problem. More complicated disorders can be another matter. From early childhood nocturnal sleep consists of nonrapid eye movement sleep (NREM) alternating with rapid eye movement sleep (REM) in 90 minute cycles. The former is thought to result from inhibition of the reticular activating system by a brain-stem serotonergic system. While catecholaminergic and acetylcholine neurones in the brain-stem are involved in the initiation of the phasic events of REM sleep, such as eye movements and irregular heart and respiratory rate, as well as the desynchronisation of the EEG [3]. It must be remembered that during sleep the brain is by no means inactive, but is monitoring the environment to a certain extent. For example if a child is asleep while an EEG is being recorded, alerting responses will occur to familiar names; and adults will awake to a slight unfamiliar sound, but not to the noise of a train which passes the house at regular intervals. May this mean that sounds of an unfamiliar kind could set in motion a chain of events with partial arousal, and often with the emotion
Received for publication: March 5,1992. Accepted for publication: March 9,1992. Correspondence address: Dr. Neil Gordon, Huntlywood, 3 Styal Road, Wilrnslow SK9 4AE, Cheshire, United Kingdom.
of fear being predominant? SLEEP WALKING AND NIGHT TERRORS Sleep walking is such an example, occurring as it does between the transition from one stage of sleep to another in a state characterised by a high arousal threshold, unresponsiveness to the environment, mental confusion, and amnesia. The EEG during this time shows a combination of deep sleep, light sleep and wakeful rhythms. Affected children may just get out of bed and walk about, with the eyes open. Usually they can avoid large obstructions and negotiate stairs; and can be led back to bed, and will quickly go to sleep. On the other hand they may be obviously confused and agitated, crying and sometimes yelling for help; and may run out of the room or even the house [4]. Night terrors, which are not that uncommon, are an extreme form of partial arousal. They can cause diagnostic difficulties, and they occur in about three per cent of children under 14 years of age. They happen during the rapid eye movement stage of sleep, and can result in great fear, and even violent behaviour [5]. The child will suddenly scream and appear terrified, usually staring without recognition at his parents. Sleep will soon be resumed, and there will usually be no memory of the events in the morning. These attacks may be confused with epileptic seizures, and a continuous EEG recording may help in differentiation. Usually there is no evidence of an underlying emotional disorder, but the possibility of some form of insecurity must be carefully checked.
Sleep walking and night terrors rarely need treatment beyond reassurance, particularly that they will disappear as the child grows older; and sometimes a limited use of drugs such as diazapam. The fact that they are seldom remembered on waking indeed suggests that only parts of the brain are active and free of the inhibition that characterizes sleep. The same kind of mechanism seems to underlie other disorders related to sleep in which parts of the brain are active and others are not.
NARCOLEPSY AND RELATED EPISODES Narcolepsy, or attacks of irresistible sleep during the daytime, tends to occur in situations when anyone may feel sleepy, such as riding on a bus or train, attending a dull lesson after lunch, or being asked to carry out some monotonous task. It had been thought that narcolepsy was at one extreme of the spectrum of sleep patterns, but the phases of sleep are abnormal in this condition. The episodes of sleep start with a rapid eye movement phase while normal sleep begins with non-REM sleep, and it has been suggested that this is a regression to a sleep pattern of infancy. Narcolepsy can occur in childhood, although it may not be diagnosed at that time unless a very careful history is taken. The onset of sleep is usually sudden, and may not last for more than ten minutes or so. Even after a short time the patients can awaken refreshed and able to immediately carryon with what they were doing, but may be drowsy. There is a danger of making a wrong diagnosis of epilepsy, but these patients can be easily woken up which is usually not the case when a child has an epileptic seizure. The episodes most often show the characteristics of REM sleep, but some patients show evidence of attacks only in NREM sleep. Only the former seem to be associated with the accessory symptoms of cataplexy, sleep paralysis, and hypnogogic and hypnopompic hallucinations. In cataplexy there is a sudden diminution of muscle tone, generalised or localised to certain muscle groups. If it is generalised the patient will fall to the ground, unable to move. The attack can follow laughter, surprise, anger or elation. Anyone can feel "weak at the knees with laughter or anger" so that there seems to be a relationship with normal behaviour, although no doubt an exaggerated one. These attacks, like other accessory symptoms, usually start about four years after the narcoleptic symptoms, and anyone who has talked to sufferers will have their own stories, such as the harpoonist who was unaffected if he did not hit his target, but if successful lost all muscle power, an obvious danger if deep under water. There seems to be a defmite relationship between cataplexy and the REM sleep motor-inhibitory process. Hypnogogic or hypnopompic hallucinations occurring in the process of falling asleep or on waking can be visual or auditory. They are usually frightening, and can be as-
sociated with sleep paralysis. They may well correspond to the dreams of REM sleep. Sleep paralysis can also occur when falling asleep or on waking and only lasts a very short time, although alarming to the sufferer who is conscious and yet cannot move; and fear is characteristic of the attacks. These episodes can usually be stopped by touching or calling the patient by name. Such hallucinations and paralyses can occur in the absence of narcolepsy. The latter may be commoner than is thought, and sufferers can be reluctant to report their symptoms for fear of being considered mentally disturbed [6]. Nocturnal epilepsy does come into the differential diagnosis of all these conditions. Seizures occurring during the night can include hallucinations and automatisms which can be very difficult to differentiate from some of the above phenomena. An important feature favouring the diagnosis of epilepsy is the recurrent, stereotyped nature of the attacks. Management of these conditions first of all depends on an accurate diagnosis. Then as full an explanation as possible must be given to the patient and the parents. Tensions of one kind or another can make these symptoms worse, so that every effort must be made to resolve these. Also any other factors which may disturb nocturnal sleep can have an adverse effect, so that the patient's daily routine should be reviewed. The use of drug treatment raises difficult problems, as in narcolepsy it is the stimulant drugs such as amphetamines and methylphenidate which are effective; and usually in large doses. It is only in adolescence that these will have to be considered, and then only if the symptoms are severe. The same can be said for imipramine in the treatment of cataplexy, although it can be quite effective [3], as can protriptyline [7].
THE KLEINE-LEVIN SYNDROME This is a rare syndrome characterised by episodes of hypersomnia, and bulimia, or rather megaphagia, as patients seem to have a compulsion to eat rather than excessive hunger [8]. Psychopathological manifestations, consisting of impaired consciousness and partial or total amnesia for parts of the episodes can occur during or following them. Retarded development and severe depression may be a feature, and gastrointestinal and autonomic disorders are common. The episodes last from several days to several weeks. No abnormal clinical or laboratory abnormalities are found, and the syndrome does not seem to be confmed to males as first suggested [9]. Also it is not restricted to the younger age group. There may be a preceding infectious illness or physical exhaustion. There seems to be an overlap with narcolepsy as symptoms typical of both syndromes can occur in the
Gordon: Sleep disturbances 183
same patient. It is postulated that there may be a dysfunction of the hypothalamus, and possibly in the reticular substance; and the syndrome should be defmed as a periodic qualitative dysregulation of food intake and sleep, with periodic mental aberrations [10].
and cardiac complications resolved [13]. Also daytime drowsiness may lead to teachers thinking the child is backward, and following the relief of the airwayobstruction there can be a marked improvement in school performance [14].
THE SLEEP APNOEA SYNDROME
CONCLUSIONS
An event during sleep, which can be easily overlooked, is the sleep apnoea syndrome. Partial or complete obstruction occurring during sleep can be due to a variety of causes from bone malformations, to muscle disorders, storage diseases, and above all to lymphoid tissue enlargement due to infection. This is one reason why the syndrome is not uncommon among children with Down syndrome. Following the anatomical abnormalities other changes are likely to occur. These involve reflexes influencing central nervous system control of breathing during sleep [8]. Because of the varied etiology full investigations will be essential before deciding on the need for treatment, and the form that this should take. Associated symptoms of sleep apnoea are excessive daytime drowsiness, loud snoring with or without respiratory pauses, insomnia, recent onset of nocturnal enuresis, abnormal or increased activity in sleep, the need to sleep sitting up or abnormal positions during sleep, frequent arousals, mouth breathing, behavioural and mood changes, and declining school performance. More rarely there can be disorientation on waking with hypnogogic hallucinations, morning headache, irritability, systemic and pulmonary hypertension, cor pulmonale, pectus excavatum, polycythaemia, and evidence of right ventricular hypertrophy on EEG and X-ray examination [12]. Nasal, laryngotracheal and other abnormalities must be excluded before obstructive episodes are attributed to enlarged tonsils and adenoids. If these are removed permanent relief may be obtained. However such enlargement alone does not warrant surgery, and significant symptoms must be witnessed, and relevant tests must be positive. Excessive daytime sleepiness resulting from nasal obstruction may be confused with narcolepsy, but in this condition the patient does not wake refreshed after sleep; and what appears to be hyperactivity may be merely the child's efforts to avoid going to sleep. If direct questions are not asked about sleeping habits, or the child is not observed while asleep, the diagnosis may well not be made; and only secondary symptoms occurring during the day may be reported. Nasal, laryngotracheal and other abnormalities must be excluded, and also the possible influence of retrognathia and obesity. Then if the tonsils and adenoids are enlarged, and the history and relevant tests are supportive, their removal may well bring relief. Subsequent rapid growth and development can be impressive,
Sleep disorders in children are under-recognised and under-treated. A detailed history is of prime importance, and reassurance for the parents that they are not wasting the doctors time when there is evidence that the symptoms are distressing for the child and the family. Many of the conditions can be treated, although advice on management is sometimes more important than drugs. As Stores [15] has pointed out little research has been done on these conditions in childhood compared with that done in adult life. For example more studies of parasomnias with video recordings and electroencephalographic monitoring would help to improve the advice that can be given.
184 Brain & Development, Vol 14, No 3, 1992
REFERENCES 1. Valman HB. ABC of 1 to 7. London: British Medical Association, 1982:6-7. 2. Richman N. Sleep disorders in young children. In: Macfarlane JA, ed. Progress in child health. Vol 2. Edinburgh: Churchill Livingstone, 1985 :i-12. 3. Zarcone V. Narcolepsy. N Engll Med 1978;87:1156-66. 4. Mahowald MW, Rosen GM. Parasomnias in children. Pediatrician 1990;17:21-31. 5. Fenwick P. Murdering while asleep. Br Med J 1986;293: 574-5. 6. Herman J, Furman Z, Cantrall G, Peled R. Sleep paralysis: a study in family practice. J Roy Coli Gen Pract 1988;38: 465-7. 7. Mitler MM, Hajdukovic R, Erman M, Koziol JA. Narcolepsy. J Clin Neurophysiol 1990;7:93-118 . 8. Smalic P, Roth B. Kleine-Levin syndrome. Ethiopathogenesis and treatment. Acta Universitatis Carolinae Medica-Monographia CXXVIII. Prague: Univerzita Karlova, 1988. 9. Critchley M, Hoffmann HL. Syndrome of periodic somnolence and morbid hunger. Br Med J 1942;i: 137-9. 10. Gallinek A. The Kleine-Levin syndrome. DisNerv Syst 1967; 28:448-451. 11. Guilleminault C, Stoohs R. Obstructive sleep apnea syndrome in children. Pediatrician 1990;17:46-51. 12. Gordon N. Nasal obstruction in childhood: the obstructive sleep apnoea syndrome. Dev Med Child Neural 1988 ;30: 261-5. 13. Talbot AR, Robertson W. Cardiac failure with tonsil and adenoid hypertrophy. Arch Otolaryngol 1973;98:277-81. 14. Kravath RE, Pollak CP, Borowiecki B. Hypoventilation during sleep in children who have lymphoid airway obstruction treated by nasopharyngeal tube and T and A. Pediatrics 1977;59:865-71. 15. Stores G. Sleep disorders in children. Br Med J 1990;301: 351-2.
The More Unusual Sleep Disturbances of Childhood Neil Gordon, MD
The sleep patterns of children often cause anxiety to their parents. Some disturbances are unusual, and therefore may cause diagnostic difficulties. Sleep walking and night te"ors can be confused with epileptic seizures. The sudden sleep of narcolepsy can lead to false accusations, when in fact the episodes are beyond the child's control. The associated phenomena of cataplexy, hypnogogic hallucinations and sleep paralysis can be particularly alarming, especially if they occur in the absence of narcolepsy. The overlap between narcolepsy and the Kleine-Levin syndrome is confirmed. Although of a different nature the sleep apnoea syndrome is equally important from the point of view of diagnosis and treatment. Key words: Sleep disorders, night walking, narcolepsy, cataplexy, hypnogogic hallucinations, Kleine-Levin syndrome. Gordon N The more unusual sleep disturbances of childhood. Brain Dev 1992; 14:182-4
Parents are often anxious about their child's sleeping habits; whether they take a long time to get to sleep, wake often in the night, or wake early. Good common sense advice should of course be given [1,2]; and this almost always solves the problem. More complicated disorders can be another matter. From early childhood nocturnal sleep consists of nonrapid eye movement sleep (NREM) alternating with rapid eye movement sleep (REM) in 90 minute cycles. The former is thought to result from inhibition of the reticular activating system by a brain-stem serotonergic system. While catecholaminergic and acetylcholine neurones in the brain-stem are involved in the initiation of the phasic events of REM sleep, such as eye movements and irregular heart and respiratory rate, as well as the desynchronisation of the EEG [3]. It must be remembered that during sleep the brain is by no means inactive, but is monitoring the environment to a certain extent. For example if a child is asleep while an EEG is being recorded, alerting responses will occur to familiar names; and adults will awake to a slight unfamiliar sound, but not to the noise of a train which passes the house at regular intervals. May this mean that sounds of an unfamiliar kind could set in motion a chain of events with partial arousal, and often with the emotion
Received for publication: March 5,1992. Accepted for publication: March 9,1992. Correspondence address: Dr. Neil Gordon, Huntlywood, 3 Styal Road, Wilrnslow SK9 4AE, Cheshire, United Kingdom.
of fear being predominant? SLEEP WALKING AND NIGHT TERRORS Sleep walking is such an example, occurring as it does between the transition from one stage of sleep to another in a state characterised by a high arousal threshold, unresponsiveness to the environment, mental confusion, and amnesia. The EEG during this time shows a combination of deep sleep, light sleep and wakeful rhythms. Affected children may just get out of bed and walk about, with the eyes open. Usually they can avoid large obstructions and negotiate stairs; and can be led back to bed, and will quickly go to sleep. On the other hand they may be obviously confused and agitated, crying and sometimes yelling for help; and may run out of the room or even the house [4]. Night terrors, which are not that uncommon, are an extreme form of partial arousal. They can cause diagnostic difficulties, and they occur in about three per cent of children under 14 years of age. They happen during the rapid eye movement stage of sleep, and can result in great fear, and even violent behaviour [5]. The child will suddenly scream and appear terrified, usually staring without recognition at his parents. Sleep will soon be resumed, and there will usually be no memory of the events in the morning. These attacks may be confused with epileptic seizures, and a continuous EEG recording may help in differentiation. Usually there is no evidence of an underlying emotional disorder, but the possibility of some form of insecurity must be carefully checked.
Sleep walking and night terrors rarely need treatment beyond reassurance, particularly that they will disappear as the child grows older; and sometimes a limited use of drugs such as diazapam. The fact that they are seldom remembered on waking indeed suggests that only parts of the brain are active and free of the inhibition that characterizes sleep. The same kind of mechanism seems to underlie other disorders related to sleep in which parts of the brain are active and others are not.
NARCOLEPSY AND RELATED EPISODES Narcolepsy, or attacks of irresistible sleep during the daytime, tends to occur in situations when anyone may feel sleepy, such as riding on a bus or train, attending a dull lesson after lunch, or being asked to carry out some monotonous task. It had been thought that narcolepsy was at one extreme of the spectrum of sleep patterns, but the phases of sleep are abnormal in this condition. The episodes of sleep start with a rapid eye movement phase while normal sleep begins with non-REM sleep, and it has been suggested that this is a regression to a sleep pattern of infancy. Narcolepsy can occur in childhood, although it may not be diagnosed at that time unless a very careful history is taken. The onset of sleep is usually sudden, and may not last for more than ten minutes or so. Even after a short time the patients can awaken refreshed and able to immediately carryon with what they were doing, but may be drowsy. There is a danger of making a wrong diagnosis of epilepsy, but these patients can be easily woken up which is usually not the case when a child has an epileptic seizure. The episodes most often show the characteristics of REM sleep, but some patients show evidence of attacks only in NREM sleep. Only the former seem to be associated with the accessory symptoms of cataplexy, sleep paralysis, and hypnogogic and hypnopompic hallucinations. In cataplexy there is a sudden diminution of muscle tone, generalised or localised to certain muscle groups. If it is generalised the patient will fall to the ground, unable to move. The attack can follow laughter, surprise, anger or elation. Anyone can feel "weak at the knees with laughter or anger" so that there seems to be a relationship with normal behaviour, although no doubt an exaggerated one. These attacks, like other accessory symptoms, usually start about four years after the narcoleptic symptoms, and anyone who has talked to sufferers will have their own stories, such as the harpoonist who was unaffected if he did not hit his target, but if successful lost all muscle power, an obvious danger if deep under water. There seems to be a defmite relationship between cataplexy and the REM sleep motor-inhibitory process. Hypnogogic or hypnopompic hallucinations occurring in the process of falling asleep or on waking can be visual or auditory. They are usually frightening, and can be as-
sociated with sleep paralysis. They may well correspond to the dreams of REM sleep. Sleep paralysis can also occur when falling asleep or on waking and only lasts a very short time, although alarming to the sufferer who is conscious and yet cannot move; and fear is characteristic of the attacks. These episodes can usually be stopped by touching or calling the patient by name. Such hallucinations and paralyses can occur in the absence of narcolepsy. The latter may be commoner than is thought, and sufferers can be reluctant to report their symptoms for fear of being considered mentally disturbed [6]. Nocturnal epilepsy does come into the differential diagnosis of all these conditions. Seizures occurring during the night can include hallucinations and automatisms which can be very difficult to differentiate from some of the above phenomena. An important feature favouring the diagnosis of epilepsy is the recurrent, stereotyped nature of the attacks. Management of these conditions first of all depends on an accurate diagnosis. Then as full an explanation as possible must be given to the patient and the parents. Tensions of one kind or another can make these symptoms worse, so that every effort must be made to resolve these. Also any other factors which may disturb nocturnal sleep can have an adverse effect, so that the patient's daily routine should be reviewed. The use of drug treatment raises difficult problems, as in narcolepsy it is the stimulant drugs such as amphetamines and methylphenidate which are effective; and usually in large doses. It is only in adolescence that these will have to be considered, and then only if the symptoms are severe. The same can be said for imipramine in the treatment of cataplexy, although it can be quite effective [3], as can protriptyline [7].
THE KLEINE-LEVIN SYNDROME This is a rare syndrome characterised by episodes of hypersomnia, and bulimia, or rather megaphagia, as patients seem to have a compulsion to eat rather than excessive hunger [8]. Psychopathological manifestations, consisting of impaired consciousness and partial or total amnesia for parts of the episodes can occur during or following them. Retarded development and severe depression may be a feature, and gastrointestinal and autonomic disorders are common. The episodes last from several days to several weeks. No abnormal clinical or laboratory abnormalities are found, and the syndrome does not seem to be confmed to males as first suggested [9]. Also it is not restricted to the younger age group. There may be a preceding infectious illness or physical exhaustion. There seems to be an overlap with narcolepsy as symptoms typical of both syndromes can occur in the
Gordon: Sleep disturbances 183
same patient. It is postulated that there may be a dysfunction of the hypothalamus, and possibly in the reticular substance; and the syndrome should be defmed as a periodic qualitative dysregulation of food intake and sleep, with periodic mental aberrations [10].
and cardiac complications resolved [13]. Also daytime drowsiness may lead to teachers thinking the child is backward, and following the relief of the airwayobstruction there can be a marked improvement in school performance [14].
THE SLEEP APNOEA SYNDROME
CONCLUSIONS
An event during sleep, which can be easily overlooked, is the sleep apnoea syndrome. Partial or complete obstruction occurring during sleep can be due to a variety of causes from bone malformations, to muscle disorders, storage diseases, and above all to lymphoid tissue enlargement due to infection. This is one reason why the syndrome is not uncommon among children with Down syndrome. Following the anatomical abnormalities other changes are likely to occur. These involve reflexes influencing central nervous system control of breathing during sleep [8]. Because of the varied etiology full investigations will be essential before deciding on the need for treatment, and the form that this should take. Associated symptoms of sleep apnoea are excessive daytime drowsiness, loud snoring with or without respiratory pauses, insomnia, recent onset of nocturnal enuresis, abnormal or increased activity in sleep, the need to sleep sitting up or abnormal positions during sleep, frequent arousals, mouth breathing, behavioural and mood changes, and declining school performance. More rarely there can be disorientation on waking with hypnogogic hallucinations, morning headache, irritability, systemic and pulmonary hypertension, cor pulmonale, pectus excavatum, polycythaemia, and evidence of right ventricular hypertrophy on EEG and X-ray examination [12]. Nasal, laryngotracheal and other abnormalities must be excluded before obstructive episodes are attributed to enlarged tonsils and adenoids. If these are removed permanent relief may be obtained. However such enlargement alone does not warrant surgery, and significant symptoms must be witnessed, and relevant tests must be positive. Excessive daytime sleepiness resulting from nasal obstruction may be confused with narcolepsy, but in this condition the patient does not wake refreshed after sleep; and what appears to be hyperactivity may be merely the child's efforts to avoid going to sleep. If direct questions are not asked about sleeping habits, or the child is not observed while asleep, the diagnosis may well not be made; and only secondary symptoms occurring during the day may be reported. Nasal, laryngotracheal and other abnormalities must be excluded, and also the possible influence of retrognathia and obesity. Then if the tonsils and adenoids are enlarged, and the history and relevant tests are supportive, their removal may well bring relief. Subsequent rapid growth and development can be impressive,
Sleep disorders in children are under-recognised and under-treated. A detailed history is of prime importance, and reassurance for the parents that they are not wasting the doctors time when there is evidence that the symptoms are distressing for the child and the family. Many of the conditions can be treated, although advice on management is sometimes more important than drugs. As Stores [15] has pointed out little research has been done on these conditions in childhood compared with that done in adult life. For example more studies of parasomnias with video recordings and electroencephalographic monitoring would help to improve the advice that can be given.
184 Brain & Development, Vol 14, No 3, 1992
REFERENCES 1. Valman HB. ABC of 1 to 7. London: British Medical Association, 1982:6-7. 2. Richman N. Sleep disorders in young children. In: Macfarlane JA, ed. Progress in child health. Vol 2. Edinburgh: Churchill Livingstone, 1985 :i-12. 3. Zarcone V. Narcolepsy. N Engll Med 1978;87:1156-66. 4. Mahowald MW, Rosen GM. Parasomnias in children. Pediatrician 1990;17:21-31. 5. Fenwick P. Murdering while asleep. Br Med J 1986;293: 574-5. 6. Herman J, Furman Z, Cantrall G, Peled R. Sleep paralysis: a study in family practice. J Roy Coli Gen Pract 1988;38: 465-7. 7. Mitler MM, Hajdukovic R, Erman M, Koziol JA. Narcolepsy. J Clin Neurophysiol 1990;7:93-118 . 8. Smalic P, Roth B. Kleine-Levin syndrome. Ethiopathogenesis and treatment. Acta Universitatis Carolinae Medica-Monographia CXXVIII. Prague: Univerzita Karlova, 1988. 9. Critchley M, Hoffmann HL. Syndrome of periodic somnolence and morbid hunger. Br Med J 1942;i: 137-9. 10. Gallinek A. The Kleine-Levin syndrome. DisNerv Syst 1967; 28:448-451. 11. Guilleminault C, Stoohs R. Obstructive sleep apnea syndrome in children. Pediatrician 1990;17:46-51. 12. Gordon N. Nasal obstruction in childhood: the obstructive sleep apnoea syndrome. Dev Med Child Neural 1988 ;30: 261-5. 13. Talbot AR, Robertson W. Cardiac failure with tonsil and adenoid hypertrophy. Arch Otolaryngol 1973;98:277-81. 14. Kravath RE, Pollak CP, Borowiecki B. Hypoventilation during sleep in children who have lymphoid airway obstruction treated by nasopharyngeal tube and T and A. Pediatrics 1977;59:865-71. 15. Stores G. Sleep disorders in children. Br Med J 1990;301: 351-2.
