Introduction

In this study, we aimed to search for clinical significance of polyspikes seen on EEGs.

Methods

We retrospectively reviewed medical charts, EEGs, and brain MRIs of children with focal epilepsy who visited Pusan National University Children’s Hospital between 2010 and 2014. The following patient were included; 1) diagnosed with focal epilepsy and was given antiepileptic drugs, 2) seizure onset age of < 18 years, 3) ≥ 1 EEG results showing focal epileptiform discharges, and 4) follow-up period of > 3 years since the diagnosis of epilepsy. The following patients were excluded: 1) had ≥ 1 unprovoked generalized seizure, 2) ≥ 1 EEG results showing generalized epileptiform discharges, and 3) whose EEGs or brain MRIs are not available for review.

Results

A total of 1125 patients (624 [55.5%] boys, median seizure onset age 5.9 [2.7-8.6] years, median follow-up duration 7.2 [4.8-8.6] years) were included. Polyspikes were seen on EEGs of 468 (41.6%) patients. Seizure frequencies and number of antiepileptic drugs at 1, 2, and 3 years after diagnosis, follow-up durations, and proportion of patients with MRI positive lesions, with drug resistant epilepsy, with intellectual disability were all significantly higher in patients who showed polyspikes on their EEGs on univariate analyses. However, on multivariate analysis, proportion of patients with MRI positive lesions was the only significantly associated factor with polyspikes on EEGs (OR 9.691, 95% CI 5.282-17.779, p < 0.001).

Conclusion

Polyspikes on EEGs in children with focal epilepsy are associated structural etiology proven by brain MRI.