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Childhood sleep disorders - parasomnias

Paediatric neurophysiologist Dr Zenobia Zaiwalla describes how to manage parasomnias in children

Paediatric neurophysiologist Dr Zenobia Zaiwalla describes how to manage parasomnias in children

41186481Sleep disorders are common in childhood and include insomnia, sleep-related breathing disorder, central causes of hypersomnia such as narcolepsy, circadian rhythm disorders and parasomnias.

This article will focus on parasomnias, which often start in childhood.

Parasomnias are undesirable physical events or experiences that occur during sleep, within sleep or during arousals from sleep and include sleep-related movements, behaviours, emotions, perceptions, dreaming and involvement of the autonomic nervous system.

Some parasomnias include emergence of so-called ‘basic drive states', such as locomotion, aggression, eating and other disinhibited behaviours.

Classifying parasomnias

Parasomnias are subdivided on the basis of the sleep stage they occur from: non-rapid eye movement (NREM) sleep or rapid eye movement (REM) sleep, occurring cyclically through the night interrupted by brief arousals. NREM sleep is further divided into stages 1-4, reflecting the progressive increase in sleep depth.

Dream content is remembered on waking from REM sleep, while there is often no memory of prearousal mentation or postarousal behaviour when woken from NREM stages 3 and 4 sleep.

Sleep-related rhythmic movement disorders

Sleep-related rhythmic movements occur in the sleep-wake transition stage at sleep onset or on waking in the night, but can also occur in other sleep stages. The movements include:

• rhythmic head banging, with the child often seeking out a hard surface to bang against

• head rolling, and

• body rolling.

These movements are common in infants and toddlers, more frequent in children with learning difficulties, reducing to around 5% by age five. They occasionally persist into adolescence and adulthood.

In the young child the main parental concern is injury, but parents can be reassured that despite forehead bruising, serious head injury will not occur. If it is disturbing the family (and even neighbours), it should be managed by measures to dampen the noise, such as padding the bed sides.

Behavioural intervention may help in the older child to reduce the sleep onset, sleep-wake transition stage movements, but is less successful when the movements occur later in the night from light sleep, when the child is less aware.

A sleep restriction programme with a brief period of hypnotic medication was reported to be effective by one group, but has not been reproduced.

In the few children in whom the movements persist, it may be necessary to refer for polysomnography to exclude intrinsic triggers for night waking, such as periodic leg movements in sleep.

NREM arousal parasomnias

NREM arousal parasomnias include:

• confusional arousals

• night terrors, and

• sleepwalking behaviours.

These all occur on abrupt arousal from deep sleep – NREM stages 3 and 4 – usually in the first third of the night, often occurring just once a night, with no memory of the night behaviour the next morning. There is a strong genetic predisposition with a family history positive.

Common triggers in childhood include:

• fever

• sleep deprivation

• emotional factors including stress and excitement

• hypnotic medication

• sudden environmental noise

• intrinsic triggers for arousals such as obstructive sleep apnoea, upper airway resistance syndrome, periodic leg movements in sleep, or signal to pass urine.

The complexity of the behaviours vary. In confusional arousals the child may just sit up with brief repetitive confused behaviour including vocalisation and go back to sleep.

Night terrors are characterised by a loud piercing scream with intense autonomic activity associated with fear. The child appears confused, resisting comfort, and does not recognise the parents. The behaviours last for up to 15 minutes.

Night terrors occur at a prevalence rate of up to 6.5% in children, reducing to 2.2 to 2.6% in 15-year-olds and adults. The behaviours usually emerge in children aged between four and 12, tending to resolve spontaneously in adolescence, but can emerge in adulthood.

Sleepwalking behaviour may be preceded by repetitive confused behaviour culminating in walking, or the child on arousal bolting or running from the perceived threat, with prominent vocalisation and autonomic features as in night terrors. This behaviour usually lasts a few minutes in children.

The child may have limited capacity to respond and negotiate objects. Inappropriate behaviours such as urinating in the wardrobe are common, although high-risk behaviours do occur.

The prevalence of sleepwalking is higher than night terrors, at around 17% up to age 12.

They often remit in adolescence, though sleepwalking may persist or emerge for the first time in adolescence or adulthood. Some 4% of adults sleepwalk, with injurious sleepwalking more likely to occur with later onset.

Management of NREM arousal parasomnias should include reassurance and identifying triggers as well as taking precautions to avoid injury. Anticipatory waking can be effective if the episodes are very frequent and can be timed. This involves fully waking the child about 15 minutes before the usual time of the night behaviour for 15 consecutive nights.

Medication should be avoided except for intermittent use, when low-dose clonazepam may help.

In an attack, the parents should be advised to agree not to challenge the experience while reassuring. They should avoid holding the child if he or she resists the hold. They should put the light on and gently guide the child back to bed. Safety should be the priority.

If the child is susceptible to more than one attack in the night, it is useful to wake them fully and encourage them to go to the toilet before settling back to sleep to break the deep sleep cycle.

Psychological factors are often important when these behaviours persist or emerge in the older child, and should be addressed.

In the very young child, polysomnography is rarely indicated. If the episodes persist in the older child, are frequent and occur more than once a night, sleep studies should be considered to exclude intrinsic triggers.

Rarely, epileptic seizures from sleep – especially frontal lobe seizures – may be mistaken for parasomnia.

Appropriate referral should always be considered if there are atypical features, especially several episodes a night, episodes occurring later in the night or associated with incontinence and injury including tongue biting.

REM sleep parasomnias

The most common REM sleep parasomnia in children is nightmares. It is estimated that 10% to 50% of children have nightmares severe enough to disturb their parents.

As these occur from REM sleep, the child is able to detail the dream content, often with themes producing anxiety. These tend to occur later in the night when REM sleep is prominent and may occur more than once a night with each REM sleep period.

Nightmares usually start between three and six years, but can start at any age. If they are persistent, psychological triggers including anxiety disorder should be explored, provided the child is not on any medication known to trigger nightmares – usually those affecting the neurotransmitters serotonin, dopamine and norepinephrine.

REM sleep behaviour disorder is characterised by abnormal behaviours from REM sleep, often associated with injury. The condition is preceded by dreams becoming more aggressive. There is loss of muscle atonia associated with REM sleep in this disorder, allowing the patient to act out the aggressive dreams.

It is essentially a disorder of adults aged 50 or older, associated with or preceding neurodegenerative disorders like Parkinson's disease, dementia with Lewy body and multiple system atrophy, and is rare in childhood.

But a parasomnia overlap disorder has been described when NREM arousal disorder, including night terrors and sleepwalking, can occur in the same individual who has REM sleep behaviour disorder, starting in childhood.

Parasomnia overlap disorder may be idiopathic or symptomatic of conditions like narcolepsy and disorders involving brainstem nuclei. Diagnosis has to be confirmed by sleep studies identifying the characteristic pattern of REM sleep behaviour disorder.

Restless leg syndrome and periodic leg movements in sleep

Restless leg syndrome (RLS) is associated with a disagreeable leg sensation usually occurring prior to sleep onset, causing an irresistible urge to move the legs. The sensation is relieved by movement. RLS is often associated with periodic leg movements (PLM) in sleep and stereotype repetitive leg movements.

Both RLS and PLM disorder were considered disorders of middle age, but in the last decade there is increasing recognition that the condition may occur in children.

Some children who present with ‘growing pains' may have RLS.

Children may present with sleep onset insomnia, disturbed night sleep and daytime tiredness.

Some 50% of patients with RLS have a positive family history, some with autosomal dominant inheritance with anticipatory pattern, subsequent generations starting symptoms progressively earlier. Co-morbidities include parasomnias and ADHD.

Conclusion

Parasomnias are common in childhood, linked to the developmental changes with sleep maturation. Children have more deep NREM stages 3 and 4 sleep.

Most are self-limiting and need only reassurance. However, if they are frequent, and persist into adolescence or start in adolescence, specialist assessment may be needed to explore psychosocial factors, exclude potential intrinsic triggers such as obstructive sleep apnoea or RLS/PLMD, and, rarely, exclude epileptic seizures in sleep.

A detailed history – including timing of the parasomnia – is important for diagnosis and identifying potential triggers.

Parasomnias, especially NREM arousal disorders, rarely occur in sleep laboratories and polysomnography recordings are only needed in the few children who may have intrinsic triggers for the arousals or other primary sleep disorders such as narcolepsy associated with parasomnias.

Dr Zenobia Zaiwalla is a consultant in paediatric clinical neurophysiology at the Park Hospital for Children and John Radcliffe Hospital, Oxford

Competing interests: None declared

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