Resection of frontal encephalomalacias for intractable epilepsy: outcome and prognostic factors

Because focal encephalomalacia is an important cause of medically intractable partial epilepsy and few studies have evaluated the efficacy and the safety of resecting focal-encephalomalacias to improve seizure control, we studied a cohort of 17 consecutive patients who underwent resection of encephalomalacias in the frontal lobes as a treatment of their intractable epilepsy.

We evaluated several factors for their value in predicting postsurgical seizure control. Pre- and postsurgical magnetic resonance imaging (MRI) scans were reviewed independently by 2 blinded investigators.

At a median of 3 years of follow-up (range 0.6-7.5 years), 12 patients (70%) were seizure-free or had only rare seizures. The presence of a focal fast frequency discharge (focal ictal beta pattern) at the beginning of seizures on scalp EEG was predictive of seizure-free outcome (p = 0.017), even among patients who had complete resection of their encephalomalacias (p = 0.016). There was no significant differences in outcome with regard to age at the time of the injury that caused encephalomalacia, interval between injury and onset of seizures, duration of presurgical seizure history, presurgical seizure frequency, age at surgery, or the completeness of encephalomalacia resection. The analysis regarding completeness of encephalomalacia resection almost reached significance, suggesting that it may also be an important predictive factor (p = 0.051).

We conclude that surgery is a very effective treatment for intractable frontal lobe epilepsy (FLE) secondary to encephalomalacias. Patients are more likely to become seizure-free if they have a focal ictal beta discharge on their scalp EEG. Complete resection of the encephalomalacia should be attempted, since our results suggest that this may be a favorable predictive factor. Moreover, the operative strategy for our patients entailed, whenever possible, complete resection of the encephalomalacias and of the adjacent electrophysiologically abnormal tissues.