Inferring Seizure Frequency From Brief EEG Recordings

*MGH Epilepsy Service, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts, U.S.A. †Sleep Division, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, U.S.A. ‡King Edward VII Memorial Hospital, and Department of Internal Medicine, Paget, Bermuda.
Journal of clinical neurophysiology: official publication of the American Electroencephalographic Society (Impact Factor: 1.43). 04/2013; 30(2):174-7. DOI: 10.1097/WNP.0b013e3182767c35
Source: PubMed


: Routine EEGs remain a cornerstone test in caring for people with epilepsy. Although rare, a self-limited seizure (clinical or electrographic only) may be observed during such brief EEGs. The implications of observing a seizure in this situation, especially with respect to inferring the underlying seizure frequency, are unclear. The issue is complicated by the inaccuracy of patient-reported estimations of seizure frequency. The treating clinician is often left to wonder whether the single seizure indicates very frequent seizures, or if it is of lesser significance. We applied standard concepts of probabilistic inference to a simple model of seizure incidence to provide some guidance for clinicians facing this situation. Our analysis establishes upper and lower bounds on the seizure rate implied by observing a single seizure during routine EEG. Not surprisingly, with additional information regarding the expected seizure rate, these bounds can be further constrained. This framework should aid the clinician in applying a more principled approach toward decision making in the setting of a single seizure on a routine EEG.

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