Improvement of sleep disturbances and behaviour in Smith-Magenis syndrome with morning melatonin
Smith-Magenis syndrome is a genetic syndrome associated with interstitial deletions of chromosome 17p11.2. Main features include congenital anomalies, abnormal behaviour and sleep/wake rhythm abnormalities. The latter have been shown to result from a reversed circadian rhythm of melatonin.[2,3] Normally, secretion of melatonin peaks at night and is minimal during the day. In Smith-Magenis syndrome melatonin reaches a peak in the daytime and is lowest during the night.[2,3] This results in early onset and offset of sleep, frequent waking during the night and hypersomnia during the day.
The inversion of the circadian rhythm of melatonin in Smith-Magenis syndrome can be considered as an extremely advanced or an extremely delayed melatonin rhythm. The therapeutic consequences differ: melatonin rhythm can maximally be delayed with exogenous melatonin administered 10 hours after endogenous melatonin onset and maximally be advanced by exogenous melatonin administered 5 hours before endogenous melatonin onset. We hypothesised that sleep disturbances in Smith-Magenis syndrome result from an extremely advanced melatonin rhythm. Consequently, we treated a patient with Smith-Magenis syndrome with melatonin, administered after endogenous melatonin onset.
A boy with Smith-Magenis syndrome was referred to our outpatient clinic at age eight years. He had been diagnosed with the syndrome at age three years, after evaluation for developmental delay. The diagnosis had been confirmed by demonstration of a 17p11.2 deletion by FISH analysis. At the time of referral, the boy¡¦s parents reported serious disturbances of both sleep and behaviour. Mean onset of sleep was at 7.30 pm, with mean waking at 4.30 am. Moreover, there was frequent nocturnal waking and need for naps during the day. The main behavioural symptoms experienced were hyperactivity and tantrums. Because of this uncontrollable behaviour, the boy had been institutionalised. The boy was treated with a morning regimen of melatonin alone. Initially, melatonin 3 mg was administered at 4 am. Over the next weeks, the time of administration was shifted towards 7 am, and some time later to 8 am. Mean waking was delayed to 7 am, and disappearance of both night awakenings and the need for naps during the day were reported. The time of onset of sleep was not influenced by the treatment. Thus, with treatment mean gain in sleep was two-and-a-half hours. In addition, behavioural disturbances improved significantly with this treatment as well. At the time of this report, the boy has been treated with this regimen for over a year and results have been consistently positive.
Behavioural symptoms and sleep disturbances in Smith-Magenis syndrome have a major impact on patients and their families. A therapeutic regimen using beta1-adrenergic antagonists has been reported to improve both behaviour and sleep disturbances in Smith-Magenis syndrome. More recently, addition of evening melatonin suppletion to this regimen has been reported to enhance this positive effect. Nine children were treated with a combination of morning acebutolol and evening melatonin, which resulted in a mean delay in sleep onset of 30 minutes and in waking by 60 minutes. The mean gain in sleep in this report was 30 minutes (rate not mentioned). The authors do not mention the considerations for administration of melatonin in the evening. Yet, evening suppletion seems logical, as by this the melatonin peak is reached at its physiological time at night.
As mentioned, we postulated that sleep disturbances in Smith-Magenis syndrome result from an extremely advanced melatonin rhythm. From the observations of the natural sleep-wake rhythm in our patient, we considered the endogenous melatonin onset to be around 7 p.m. Previous observations have shown serum melatonin peaks around this time in several other Smith-Magenis patients.[3,5,6] Consequently, we treated our patient with melatonin administered several hours after this moment, with the time of administration gradually being shifted towards a normal waking time. With this treatment, the boy¡¦s waking time shifted along with the time of administration. By this, eventual gain in sleep was two-and-a-half hours. In contrast, De Leersnijder et al. reported a mean gain in sleep of 30 minutes with melatonin and acebutolol, and no gain in sleep as much as two -and-a-half hours was reached in any of the nine children studied. This suggests that a treatment regimen with morning melatonin may be more successful in restoring a normal sleep pattern in Smith-Magenis syndrome than is treatment with both a beta1-adrenergic antagonist and evening melatonin. Thus far, our observations have been limited to a single case. Yet, in our opinion the results of treatment in this case are solid and may point to a new direction in the search of adequate therapy of sleep disturbances in Smith-Magenis syndrome.
The observations in this case support our hypothesis that sleep disturbances in Smith-Magenis syndrome are due to advancement of the endogenous melatonin rhythm. The circadian disorder in Smith-Magenis syndrome may well reflect an Advanced Sleep Phase Syndrome, characterised by an advanced sleep-wake and melatonin rhythm. In this syndrome, a defect in the Per2 clock gene has been demonstrated, whereas in the Delayed Sleep Phase Syndrome, characterised by a delayed sleep-wake and melatonin rhythm, a defective Per3 clock gene has been found. Clock genes of Smith-Magenis patients are currently under investigation and may provide further insight in the nature of the underlying sleep syndrome.
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