Katharine Gammon

November 06, 2012

HUNTINGTON BEACH, California — Pediatric seizures aren't random but rather occur in day-night and sleep-wake patterns that relate to the parts of the brain that are involved, a new study suggests.

"It's important to recognize the patterns, because when we know there is more risk, more action can be taken to mitigate that risk," lead investigator Sriram Ramgopal, MD, neurology research fellow at Children's Hospital Boston in Massachusetts, told Medscape Medical News.

The findings were presented here at the Child Neurology Society 41st Annual Meeting.

Milena Pavlova, MD, neurologist at Brigham and Women's Hospital in Boston, who was not involved with the study, commented that the study adds important information to the field.

"The authors extend the prior knowledge of seizure distribution along the time of day by analyzing the evolution of each seizure," she said. "Their conclusion is that not only do seizures have a higher likelihood to occur at specific times of the day, but also the evolution of each seizure may depend on the time of day as well."

Different Seizures, Different Times

The researchers reviewed charts from 281 pediatric patients with focal epilepsy undergoing video electroencephalography for seizures in 3-hour time blocks and out of wakefulness or sleep.

Those patients had 1264 seizures overall. Frontal-lobe seizures were more likely to happen during sleep (P < .001), whereas temporal and occipital-lobe seizures more frequently occurred during the day (P < .0001 and P < .001, respectively).

For frontal-lobe seizures, motor seizures occurred most frequently between midnight and 3 am, and during sleep. Atonic seizures occurred more often when a child was awake. In temporal-lobe seizures, the researchers found auras happened most often between 12 pm and 3 pm.

Dr. Ramgopal said that there were limitations to doing a retrospective study. "In a prospective study, [you] could use a biomarker to link circadian rhythms in a more interesting way." He recognized the challenge of pulling apart a patient's sleep-wake cycle from the cycle of the clock.

Dr. Pavlova agreed that the clock presents a challenge. "One inherent limitation of this research, present in most studies published to date, is that the effect of sleep/wake state cannot be reliably distinguished from the effect of the time of day, because sleep tends to occur in the nocturnal hours."

Low-Tech Methods

Still, the data point to some low-tech methods of improving patient outcomes. Dr. Ramgopal said that differential dosing could help.

"Basically, you give the same total amount of drug, but more in evening so there is enough drug in the plasma to make sure the seizures don't happen when they're most susceptible," he explained. "It's a low-tech and easy-to-apply potential solution."

He pointed to recent studies by LM Guilhoto, MD, also from Children's Hospital Boston, and colleagues, that changed the timing of dosing in patients with nighttime seizures and resulted in a 50% overall reduction in seizures. "This has not fully studied yet, so I'm not advocating in large-scale, but it does have a lot of potential to help."

Dr. Ramgopal says that more high-tech methods of monitoring seizures can also help. For example, smartphone apps that allow parents to log seizures are available.

"Sometimes when parents see the neurologist, they give a vague history, saying that a child had a seizure last time at grandma's house," he explained. "Now there's a push towards smartphone apps, which can record seizures as they happen, which give the neurologist more detail to target treatment towards those times."

Dr. Ramgopal and Dr. Pavlova have disclosed no relevant financial relationships.

Child Neurology Society (CNS) 41st Annual Meeting: Abstract 9. Presented November 2, 2012.