Resection of bilateral occipital lobe lesions during a single operation as a treatment for bilateral occipital lobe epilepsy

Abstract

Background: Neurosurgical treatment of severe bilateral occipital lobe epilepsy usually involves two operations several mos apart.

Aim: To evaluate surgical resection of bilateral occipital lobe lesions during a single operation as a treatment for bilateral occipital lobe epilepsy.

Methods: This retrospective case series included patients with drug-refractory bilateral occipital lobe epilepsy treated surgically between March 2006 and November 2015.

Results: Preoperative evaluation included scalp video-electroencephalography (EEG), magnetic resonance imaging, and PET-CT. During surgery (bilateral occipital craniotomy), epileptic foci and important functional areas were identified by EEG (intracranial cortical electrodes) and cortical functional mapping, respectively. Patients were followed up for at least 5 years to evaluate treatment outcome (Engel grade) and visual function. The 20 patients (12 males) were aged 4-30 years (median age, 12 years). Time since onset was 3-20 years (median, 8 years), and episode frequency was 4-270/mo (median, 15/mo). Common manifestations were elementary visual hallucinations (65.0%), flashing lights (30.0%), blurred vision (20.0%) and visual field defects (20.0%). Most patients were free of disabling seizures (Engel grade I) postoperatively (18/20, 90.0%) and at 1 year (18/20, 90.0%), 3 years (17/20, 85.0%) and ≥ 5 years (17/20, 85.0%). No patients were classified Engel grade IV (no worthwhile improvement). After surgery, there was no change in visual function in 13/20 (65.0%), development of a new visual field defect in 3/20 (15.0%), and worsening of a preexisting defect in 4/20 (20.0%).

Conclusion: Resection of bilateral occipital lobe lesions during a single operation may be applicable in bilateral occipital lobe epilepsy.

Keywords: Bilateral lesions; Drug-resistant epilepsy; Occipital lobe epilepsy; One-stage surgery; Treatment outcome; Visual fields.

Figure 1

Surgical resection of bilateral occipital lesions. A and B: The extent of the bilateral occipital craniotomy; C: Intracranial cortical electrodes were placed on the surface of the bilateral occipital lobe during surgery to enable monitoring of the electroencephalography; D: Photograph taken after resection of the lesions in the bilateral occipital lobe.

Figure 2

Clinical findings in a 15-year-old male patient with bilateral occipital lobe epilepsy. A: Scalp video-electroencephalography (EEG) recordings demonstrated abnormal discharges in the right occipital region during the interictal period; B and C: magnetic resonance imaging (MRI) revealed abnormal signals in the bilateral occipital lobe; D: T2-FLAIR MRI showed irregular high signals in the bilateral occipital lobe that suggested ischemic changes; E: A subdural grid electrode was placed during surgery under general anesthesia; F: Anteroposterior and lateral head X-rays (taken after closure of the craniotomy) showing the position of the subdural grid electrode; G-I: Representative EEG recordings made using the subdural grid electrode showing abnormal discharges arising from both sides of the occipital lobe; The upper half of each trace shows recordings obtained from the left occipital lobe, and the lower half of each trace shows recordings obtained from the right occipital lobe; J: Postoperative cranial computed tomography.

Figure 3

Clinical findings in an 11-year-old male patient with bilateral occipital lobe epilepsy. A: Representative scalp video-electroencephalography (EEG) recording demonstrating abnormal discharges originating in the left occipital region during the interictal period; B: Representative scalp video-EEG recording demonstrating abnormal discharges originating in the right occipital region during the interictal period; C-E: magnetic resonance imaging showing bilateral occipital dysplasia and a high signal on T2-FLAIR imaging that was obvious on the right side; F: Anteroposterior X-ray illustrating the position of the subdural grid electrode; G and H: Representative EEG recordings made using the subdural grid electrode showing abnormal discharges arising from both the left (G) and right (H) sides of the occipital lobe; I: Postoperative cranial computed tomography.