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Can Patients Accurately Report Seizure Frequency?
Abstract & Commentary
By Cynthia Harden, MD, Professor of Neurology, Weill Medical College of Cornell University. Dr. Harden reports no financial relationships relevant to this field of study.
Synopsis: Patients with epilepsy are unaware of most of their seizures. Video-EEG is the most reliable method to accurately determine seizure frequency.
Source: Hoppe C, Poepel A, Elger CE, et al. Epilepsy: accuracy of patient seizure counts. Arch Neurol 2007;64:1595-1599.
This study aimed to determine if reminding adult epilepsy inpatients to record seizure occurrence would improve documentation accuracy when compared to actual seizure occurrence on inpatient video-EEG recording. Ninety-one consecutive adult partial epilepsy patients were asked to document the occurrence of seizures during inpatient video-EEG monitoring. This information was then compared for accuracy against the actual recorded seizure occurrence. Out of 582 partial seizures recorded, patients failed to document 55.5% of seizures; daily reminders to record seizures did not improve the documentation rate. Seizures originating in the left hemisphere, either frontal or temporal, complex partial seizures, and seizures during sleep were associated with patients' documentation failure.
Important exclusion criteria were a history of pseudoseizures, prolonged subclinical seizure activity, and generalized epilepsy, for which an aura or immediate seizure warning usually would not occur. Not surprisingly, reminding the patients did not improve seizure documentation as compared to a group of patients randomly assigned not to have daily reminders.
The striking finding of this report is that the detection rate of seizure occurrence by patient report is very low, with patients reporting only about one-half of the seizures recorded on video-EEG. This was not improved by encouraging vigilance for seizure occurrence; therefore, this gap in reporting is likely accounted for by the patients' lack of awareness of the events, not by lack of effort. This assumption is supported by the finding that seizures during sleep were especially poorly remembered by patients, with only 14% reported. Furthermore, complex partial seizures, which often involve mesial temporal structures important for recall, were only reported 27% of the time compared to video-EEG capture. The authors do not speculate as to why left frontal and temporal seizures were less frequently remembered than right sided seizures, but do suggest a role of the left hemisphere in seizure awareness.
This study brings to light what neurologists working in epilepsy have long realizedpeople with epilepsy simply do not know how many seizures they are having. The seizures reported during office visits are a distillation of the patient's seizure experience and must be considered as a surrogate for the actual number of seizures that have occurred. This is the reality for persons with epilepsy and for epileptologists who have time and again watched video-EEG recordings of seizures for which the monitored patient has no recall.
The frequency of unreported seizures in persons with epilepsy due to lack of awareness of their occurrence illustrates the importance of long-term video EEG monitoring or overnight ambulatory EEG monitoring. These procedures can inform the neurologist about the frequency, severity, and localization of seizures and can extend, validate or refute the report by the patient. Frequent unreported seizures may be associated with several important comorbidities in epilepsy such as injury and sudden unexpected death in epilepsy patients. Video-EEG or ambulatory EEG monitoring should be considered for a broad spectrum of seizure patients to help the neurologist further understand the epilepsy syndrome in that particular patient, such as how many and what type of seizures actually are occurring. This would help to improve care for patients, in terms of guiding medical and surgical treatments for epilepsy.