Long-term outcomes after nonlesional extratemporal lobe epilepsy surgery

Area of Science:

• Neurosurgery
• Epileptology
• Diagnostic Imaging

Background:

• Focal lesions on MRI predict favorable epilepsy surgery outcomes.
• Patients with normal MRI findings and extratemporal lobe epilepsy often have less favorable surgical outcomes.
• Previous studies on nonlesional extratemporal epilepsy surgery outcomes are limited.

Observation:

• This retrospective study evaluated 85 patients with medically resistant nonlesional extratemporal epilepsy and normal MRI findings.
• Noninvasive diagnostic tests were assessed for their association with excellent surgical outcomes (Engel classes I-IIA).
• A hypothesis for seizure origin was possible in 55% of patients, leading 66% to intracranial EEG monitoring.

Findings:

• Scalp EEG was the most useful noninvasive test for predicting excellent surgical outcomes in this patient group.
• Localized interictal epileptiform discharges on scalp EEGs were associated with excellent surgical outcomes.
• Of 24 patients undergoing resective surgery, 38% achieved excellent outcomes; overall, only 11% of the initial 85 patients had long-term excellent outcomes.

Implications:

• Scalp EEG is crucial for selecting patients with nonlesional extratemporal epilepsy for further evaluation and potential surgery.
• Accurate prediction of surgical success remains challenging in nonlesional extratemporal epilepsy.
• Further research is needed to improve outcomes for patients with medically resistant nonlesional extratemporal epilepsy.