Sleep disorders with neurological disease: Viva

Opening question

Examiner: This boy with autism takes two hours to settle and wakes through the night. How do you approach the assessment, and what is the most likely category of sleep disorder here?

Candidate: I would start with a structured sleep history and a two-week sleep diary, asking separately about sleep onset latency, night wakings and their triggers, total duration, morning mood, and the daytime impact on behaviour and learning. In a child with autism, the most likely category is a dyssomnia, specifically chronic insomnia of the neurodevelopmental disorders, because bedtime resistance and night-waking are the commonest sleep complaint in autism, occurring in 40 to 80 per cent of these children. I would use the Sleep Disturbance Scale for Children to screen for the other clusters and to track response, because a sleep disorder here is the expected finding, not the exception. [9]

Examiner: Good. Before you reach for a drug, what non-pharmacological measures would you put in place? [9]

Candidate: The foundation for every child is sleep hygiene and behavioural therapy, and this layer alone resolves a large fraction of chronic insomnia, so it must never be skipped. I would build a consistent bedtime routine, a regular rise time, removal of screens and caffeine from the evening, and a behavioural programme such as graduated extinction or sleep scheduling, adapted to his developmental level and supported by his parents and his school team. [9]

Escalation: pharmacotherapy

Examiner: Suppose behavioural measures are optimised but he still takes well over an hour to settle. What next? [2]

Candidate: The second-line agent after behavioural measures have been optimised is prolonged-release melatonin, which the Gringras randomised trial established as effective and safe for the insomnia of autism, shortening sleep latency and lengthening total sleep. I would start it under specialist guidance, review against the diary, and counsel the family that melatonin works with the routine, not instead of it, and that the long-term Maras extension confirmed sustained benefit. [2] [3]

Examiner: And if the picture were not insomnia but an urge to move the legs in the evening, relieved by movement, with bedtime resistance? [5]

Candidate: That is restless legs syndrome, a sleep-related movement disorder, and I would check a serum ferritin, because a ferritin below 50 micrograms per litre supports the diagnosis and predicts response to iron. I would start oral iron, and for the child who fails oral iron or cannot tolerate it, the DelRosso trial established intravenous ferric carboxymaltose as effective for refractory paediatric restless legs syndrome, so a proven parenteral option exists. A sedative is the wrong choice here, because it would worsen the movements. [5]

Distinguishing the mimic

Examiner: A parent brings video of their child sitting up in bed, staring, and performing repetitive movements for a minute, several times a night. How do you decide whether this is a parasomnia or a seizure? [11]

Candidate: The discriminator I rely on is the pattern. A parasomnia, a disorder of arousal such as a confusional arousal or sleep terror, is variable in its form, lasts several minutes, occurs once or twice a night, and is confined to slow-wave sleep in the first third of the night, with the child amnesic for it. Nocturnal frontal lobe epilepsy, by contrast, is stereotyped and brief, lasts under a minute, may occur several times a night, and can arise in any sleep stage. A stereotyped, brief, recurrent event points to a seizure and warrants video-electroencephalography, ideally in the sleep laboratory, because missing nocturnal frontal lobe epilepsy leaves a treatable epilepsy untreated. [11]

Examiner: And how would you investigate a sleepy child with cataplexy? [1]

Candidate: Cataplexy, the sudden emotion-triggered loss of muscle tone with preserved consciousness, is pathognomonic for narcolepsy type 1, the loss of hypothalamic orexin neurons. I would arrange an overnight polysomnography to exclude other causes of sleepiness, then a multiple sleep latency test the next morning. A mean sleep latency of eight minutes or less with two or more sleep-onset REM periods confirms a central disorder of hypersomnolence, and with cataplexy present this is narcolepsy type 1. Where cataplexy is absent or ambiguous, cerebrospinal fluid orexin below 110 picograms per millilitre is the definitive biomarker. The orexin receptor 2 agonists now offer a mechanism-targeted therapy. [1] [12]

The technology-dependent child

Examiner: Returning to the girl with Duchenne muscular dystrophy and a rising morning carbon dioxide. What is happening, and what will you do? [7]

Candidate: She has symptomatic nocturnal hypoventilation, which is the expected evolution of the respiratory muscle weakness of Duchenne muscular dystrophy and is a precursor to daytime respiratory failure. This is an emergency in slow motion, and untreated it progresses to cor pulmonale and death. I would arrange polysomnography with capnography to confirm the rising nocturnal carbon dioxide and the intermittent desaturation, and I would initiate non-invasive ventilation, typically bilevel support, in consultation with the respiratory and sleep service. The principle is that a rising overnight carbon dioxide is the trigger to ventilate, and acting early changes the prognosis. [7] [11]

Examiner: Last question. What single principle ties all of this together? [9]

Candidate: The relationship between sleep and the brain is bidirectional. The brain makes sleep through orexin neurons, the circadian pacemaker, and the REM-atonia circuit, and neurological disease attacks these systems. In return, fragmented and hypoxic sleep lowers the seizure threshold, impairs learning, magnifies behavioural dysregulation, and increases tone. Treating sleep is therefore a direct treatment of the neurological condition, not a comfort measure, and case-finding sleep disorders in every neurodisability and epilepsy clinic is the main work that changes outcomes. [9] [7]