Abnormal VEEG Is a Risk Factor for Recurrence After First Unprovoked Seizure

Researchers at Sichuan University in China investigated the utility of 24-hour video-EEG (VEEG) in evaluating the risk of recurrence following an initial unprovoked seizure in 134 patients aged 3 to 77 years (66.4% male). Their results were reported in Seizure.¹

The lifetime risk of experiencing at least one seizure is as high as 10% in the general population, and an estimated 3% of individuals will develop epilepsy.² Based on the practical clinical definition of epilepsy established by International League Against Epilepsy (ILAE), a “first seizure with an abnormal EEG or brain imaging cannot be diagnosed as epilepsy unless there is sufficient evidence to substantiate a recurrence risk of more than 60%…,” the study authors wrote.³ However, previous findings regarding the value of EEG in predicting recurrence risk have been inconclusive.

In the current study, participants were screened for inclusion by 2 epileptologists. Patients whose first seizures were categorized as generalized, partial, or status epilepticus, as well as those who had experienced clusters of 2 or more seizures within 24 hours, were included in the study. Those with other types of seizures, non-epileptic seizures, and seizures resulting from acute factors were excluded. Participants underwent 24-hour VEEG within 7 days of the initial unprovoked seizure, and 2 blinded experts interpreted the results. Follow-up sessions took place at 3, 6, 12, and 24 months following the first seizure, unless patients experienced a recurrence, in which case follow-up was discontinued and treatment with AEDs was initiated.

According to their findings, the overall risk of recurrence for the total sample was 51.5%. VEEG abnormalities were detected in 56.7% of patients, and these were a statistically significant predictor of recurring seizure, according to multivariate analysis using Cox regression [RR 2.84, 95% confidence interval (CI) 1.67-4.82, P < .001]. The recurrence risk was especially high (73.2%) in patients showing epileptiform discharge abnormalities. In this group, the risk was greater among patients with epileptiform discharges vs those with normal results or nonsignificant abnormalities on VEEG (RR 2.76, 95% CI 1.83-5.34, P < .001 and RR 2.05, 95% CI 1.14-3.82, P < .001, respectively). There was no significant difference in recurrence rates between patients with generalized and focal epileptiform discharge abnormalities (RR 1.09, 95% CI 0.44-2.69, P = .85).

The observed risk of recurrence “would meet the diagnostic criteria for the patients with a first unprovoked seizure and a VEEG with epileptiform discharge abnormality and could be used to diagnose epilepsy according to the practical clinical definition of epilepsy published by ILAE in 2014,” the authors concluded.

References

1. Chen T, Si Y, Chen D, et al. The value of 24-hour video-EEG in evaluating recurrence risk following a first unprovoked seizure: A prospective study. Seizure. 2016; 40:46-51.
2. Pohlmann-Eden B, Beghi E, Camfield C, Camfield P. The first seizure and its management in adults and children. BMJ. 2006; 332(7537): 339–342.
3. Fisher RS, Acevedo C, Arzimanoglou A, et al. ILAE official report: a practical clinical definition of epilepsy. Epilepsia. 2014; 55(4):475-82.