Video EEG may be more likely to capture an event of interest if a patient has had frequent past events, if the last event was within 24 hours of admission, and if the patient has an intellectual disability, according to a retrospective study published online ahead of print January 27 in Pediatric Neurology. Video EEG probably would not be as informative for developmentally normal children or for children who have less frequent events with more time between them, said Elaine C. Wirrell, MD, Professor of Neurology at Mayo Medical School in Rochester, Minnesota.
The study examined 213 children who underwent prolonged inpatient monitoring at one institution during a recent three-year period. Its findings can help neurologists counsel families about the likelihood of having a successful admission. The research also could prompt neurologists to suggest that patients and their caregivers try to capture an event on their own, said Dr. Wirrell.
“The utility of [video EEG] monitoring for events that do not occur at least on a weekly basis is limited, even in the context of identifiable provocative factors,” she explained. “With the ubiquity of cellular phone video cameras, asking parents to make a recording of a rare event when it occurs in vivo so that a child neurologist may review it in conjunction with the remainder of the clinical history and a routine EEG may be higher yield than video EEG monitoring, at least as an initial step.”
High-Frequency Events Were More Likely to Be Recorded
The children’s (ages 2 to 13) inpatient stays were intended to capture physical events related to EEG changes. The median recording duration was 25 hours, and the length of recordings ranged from 22 to 48 hours.
The monitoring captured at least one event in 66% of the children at a median monitoring duration of 4.5 hours. The median time to capturing an EEG-related event was directly related to how often the events occurred before admission. For children who had daily events, the median time to capture an event was approximately four hours. For children who had events at least three times per week, the median time to capture an event was 24 hours. For children who had events once or twice per week, the median time to capture an event was 23 hours. The median time to capture an event was approximately eight hours for children whose events occurred less than once per week.
The events that occurred most frequently (ie, at least three times per week) were recorded during admission 72% of the time. The recording rate was 41% for events that occurred at frequencies ranging from less than three times per week to once monthly. The recording rate was 26% for events that occurred less than once monthly.
In general, the sooner a child was brought in for monitoring, the more successful the procedure. The median time to capture an event was almost four hours if the previous event had happened less than 24 hours before admission, compared with 22.4 hours if the previous event had happened between 24 and 72 hours before admission, and 22.7 hours if it had occurred between 72 hours and one week before admission. But the median time to capture an event was approximately 15 hours if the previous event had occurred more than one week before admission.
Events were captured 71% of the time when the previous event had occurred less than 24 hours before admission. The capture rate was 52% when the previous event had occurred between 24 and 72 hours before admission and 32% when it had occurred more than 72 hours before admission. The highest preadmission event frequency significantly increased the chance of capturing an event (odds ratio [OR], 3.77), as did the shortest event latency (OR, 2.31).
Dosing Changes May Decrease the Likelihood of Successful Monitoring
Intellectual disability in the patient significantly increased the likelihood of capturing an EEG-related event (OR, 3.26). But the common practices of sleep deprivation and antiepileptic medication withdrawal did not increase the likelihood of capturing one, said Dr. Wirrell. Medication withdrawal or dose change decreased the chance of an event capture (OR, 0.46).
That finding “came as a surprise,” the investigators noted. Its significance is uncertain, however, because it was not a prespecified outcome, and not many patients were in these subgroups. “It typically takes five half-lives to reach a new steady state of each medication adjustment,” said Dr. Wirrell. “Therefore, depending on the half-life duration of the medications, levels may not become subtherapeutic for several days after discontinuation or dose reduction.”