gms | German Medical Science

Objective: A retrospective study was performed to analyze the impact of functional neuronavigation and intraoperative magnetic resonance imaging (iopMRI) during surgery of extratemporal epileptogenic lesions on neurological and epilepsy outcome.

Methods: From 2003–2011 twenty-five patients with a mean age of 36 years (range: 12–67; 14 female, 11 male) suffering from intractable extratemporal epilepsy were resected on focal epileptogenic lesions close to speech / motor areas or adjacent to the visual tract. The mean preoperative duration of epilepsy was 12.4 (0–34) years. Before operation motor-sensory (11 patients) and speech areas (17 patients) were mapped using functional MRI. In addition, pyramidal tract, fasciculus arcuatus (14 patients) and visual tracts (8 patients) were visualized by diffusion tensor imaging (DTI). The mean distance between eloquent areas and the defined lesion was 8 (0–25) mm. Functional data were integrated into intraoperative neuronavigation and displayed through the microscope during surgery. Histopathology included focal cortical dysplasia in 5 cases, gliosis in 6, dysembryoblastic neuroepithelial tumor in 2, cavernous hemangioma in 5, ganglioglioma WHO°I in 4 and glioma WHO°I-III in 3 patients. The postoperative follow-up period was 37.2 (4–89) months on the average.

Results: According to iopMRI scans, 100% resection of the epileptogenic lesions was achieved in all patients. In 4 of them, an intraoperative second look procedure according to iopMRI was necessary to complete resection. Transient neurological deterioration with a dysphasia was seen in 2/14 patients, permanent dysphasia found in 2/14 patients. Permanent quadrantanopia was observed in 2/8 patients. Of patients with functional mapping of the motor cortex and pyramidal tract, 1/19 experienced a temporary monoparesis. A favourable seizure control (Engel classification I and II) was achieved in 80% of the patients.

Conclusions: In our retrospective analysis, we demonstrated that resection of the epiletogenic lesions close to the eloquent cortex and fibre tracts can be performed safely and efficiently by the integration of multimodal neuronavigation and functional imaging during surgery.