Melatonin as an Alternative to Sedation in Pediatric Electroencephalography: Need to Exercise Caution!

Behavior training and sleep deprivation are mostly successful in getting electroencephalography (EEG) recordings in children. However, in cases where sleep EEG is required or child is uncooperative, sedation becomes necessary.

Chloral hydrate, a sedative-hypnotic drug, has been in use for sedation of children undergoing EEG for over two decades now.[1] [2] Chloral hydrate, though mostly reported to be safe when used for sedation in pediatric procedures, does require continuous monitoring. Hence, numerous alternatives to chloral hydrate for sedation in pediatric EEGs have been studied over the years. The most promising of all these has been reported to be melatonin.

For a more accurate syndromic classification of epileptic disorders, increasing yield of EEGs in detecting epileptiform discharges is very beneficial. Natural sleep and sleep deprivation are known to increase the EEG yield in detecting epileptiform discharges. Melatonin, mainly produced in pineal gland and a natural sleeping agent, is known to be an efficient sedative, hypnotic, analgesic, anti-inflammatory, and anti-oxidative.[3] Melatonin as an alternative to sedation in children undergoing sleep EEG recording has been reported to be highly efficacious by a few recent studies.[4] [5] Various parameters like time to sleep onset and duration of sleep with melatonin administration were found to be similar to that with chloral hydrate.[4] Another study reported shorter sleep duration and drowsiness period with melatonin as compared with chloral hydrate.[5] However, none of these studies have objectively looked into quality of EEG recordings (yield of EEGs in detecting epileptiform discharges with and without use of melatonin in same subjects) obtained while using melatonin for sedation. With growing evidence of anticonvulsant properties of melatonin based on vast experimental data, the major concern arising is whether melatonin exerts a significant effect on brain electrical activity thereby directly affecting the EEG recording. Melatonin has been shown to modulate the electrical activity of neurons by reducing glutamatergic and enhancing GABA-ergic neurotransmission.[6] [7] The indoleamine may also be metabolized to kynurenic acid, an endogenous anticonvulsant.[7] Few recent studies have highlighted significant anti-epileptic properties of melatonin.[8] [9] [10] Anti-epileptic property of melatonin was confirmed in pentylenetetrazole and electrically induced convulsions in mice where significant increase in seizure threshold after administration of melatonin was reported.[9] In such a case, melatonin can directly interfere with the EEG recording, thereby decreasing the yield of EEGs in detection of epileptiform discharges. If further studies substantiate the anti-epileptic properties of melatonin in children with epilepsy, use of melatonin as an alternative to sedation for pediatric EEGs would need to be investigated thoroughly in terms of its effect on reduction in epileptiform activities, thereby decreasing the yield of EEG. Till then, caution is advised in interpretation of pediatric sleep EEGs obtained using melatonin as a sedative agent.

• References

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