When a child loses milestones, consider sleep EEG studies
When a 2- or 3-year-old child begins losing milestones like language, walking skills and fine motor abilities, or is slow to achieve them, it’s devastating for families. The good news, at least for some children, is that it might be treatable.
Tobias Loddenkemper, MD, a neurologist in the Epilepsy Center at Boston Children’s Hospital, suspected that some children with developmental delay have seizure-like activity in the brain at night. These spikes of electrical activity, referred to medically as sleep-potentiated epileptiform activity, can be readily and inexpensively detected by electroencephalography, or EEG, and readily treated with nighttime anti-seizure drugs.
But likely, no one’s thought of it. “Very few physicians have been looking to see what’s happening at night,” Loddenkemper says.
He and research fellow Iván Sánchez Fernández, MD, with other colleagues, decided to look themselves. They reviewed overnight EEG recordings from 147 patients who were seen at Boston Children’s over a 14-year period. They found that 100 of the 147 children indeed had prominent spikes in their EEGs during the night – and about one in five of them did not have known epilepsy.
“Kids can have an almost normal EEG while awake, but show increased spikes during sleep,” says Loddenkemper.
MRI imaging, also done on the children, suggested that the spikes may reflect early, unrecognized strokes or other early injuries to the developing brain. Brain lesions were found in 48 percent of the children with spikes, but in only 19 percent of those without spikes; lesions in the thalamus were especially common. Early stroke was the single most common type of brain injury, found in 14 percent of children with spikes but none of the controls.
Loddenkemper and Sánchez Fernández speculate that these early brain injuries disrupt circuit formation in the developing brain, making it over-excitable – and leading to too much cross-talk that can impinge on learning and development. The EEG spikes were most often seen during slow-wave sleep, a phase when memories are formed; if this phase is always interrupted by spikes, learning ability is likely to be impaired, Loddenkemper says.
“We know that children lose skills and show features of autism when these spikes appear,” he says. “These children lose out on a critical period of brain development and may never fully catch up later in life.”
Loddenkemper is urging his fellow physicians to consider sleep EEG monitoring more often in children not meeting developmental milestones, and to consider giving medications at bedtime if heightened brain electrical activity is found. In a recent study, Loddenkemper, Sánchez Fernández and several other epileptologists found that high doses of Valium before sleep reduced nighttime spiking.
He and Sánchez Fernández are now developing a larger clinical trial to test the effects of a newer benzodiazepine dosed in the evening. They expect this trial will provide a better understanding of how nighttime seizure-like activity influences autistic features and loss of developmental milestones.
“Developmental delay may be the only clinical finding in some children,” says Loddenkemper. “You can’t pick up the source unless you do a nighttime EEG, and there’s a therapy for it.”
This continues a focused look at epilepsy and autism. There seems to be some wider implications for other special needs children , those defined as having a developmental delay and suggests that many of the difficulties these children face in education and learning may be alleviated to some some extent by early intervention through a substantive medical work up.
More of Dr Loddenkemper’s research here …
Early thalamic lesions in patients with sleep-potentiated epileptiform activity.
Short-term response of sleep-potentiated spiking to high-dose diazepam in electric status epilepticus during sleep.
Risk Factors for Autistic Regression: Results of an Ambispective Cohort Study.