Dipolar EEG Spikes Are More Benign.

Purpose: Rolandic epileptiform discharges with tangential dipole (T-dipole) configurations are associated with favorable prognosis. Whether the same is true for T-dipole epileptiform discharges in other brain regions is less established and is the objective of this study.

Methods: Over 20 years, patients with epileptiform discharges were identified as follows: frontal (F = 176), temporal (T = 196), central (C = 201), parietal (P = 120), and occipital (O = 205). T-dipoles were documented. Clinical features of children with and without T-dipole were compared both regardless of brain region and separately for each brain region.

Results: The prevalence of T-dipoles was 232/898 (25.8%) overall and within different regions as follows: T = 104 (53.1%), O = 51 (24.9%), P = 23 (19.2%), C = 35 (17.4%), and F = 19 (10.8%). Most had epilepsy (T-dipole: 193 [83.2%] and nondipole: 532 [79.9%]). Regardless of region, T-dipole was associated with less drug-resistant epilepsy (11 [4.7%] vs. 202 [30.3%], P < 0.001), developmental delay (57 [24.6%] vs. 436 [51.0%], P < 0.001), school performance difficulties (SPD) (101 [43.5%] vs. 410 [61.6%], P < 0.001), autism (30 [12.9%] vs. 127 [19.1%], P = 0.037), and abnormal examination (28 [12.1%] vs. 257 [38.6%], P < 0.001]). Within different brain regions, on logistic regression, T-dipole was associated with lower odds of drug-resistant epilepsy (F, T, C, P, and O), developmental delay (F, T, C, and P), SPD (F, T, and C), autism (F and T), abnormal examination (F, T, C, and O), and abnormal neuroimaging (T, C, P, and O).

Conclusions: On routine EEG analysis, focal epileptiform discharges with T-dipoles, regardless of brain region, are associated with a more favorable clinical course.