gms | German Medical Science

Objective: Gangliogliomas (GG) are among the most common lesions causing medically refractory epilepsy. Incomplete resection or early recurrences are common in patients with eloquent located tumours resulting in persistent epilepsy. Neuronavigation combined with intraoperative high-field MR imaging (iopMRI) may improve complete resection even in eloquent located tumours and contribute to a better surgical and seizure outcome.

Method: We retrospectively identified fifty-two patients (25 female, 27 male, mean age 31.7 ± 14.8 years) with gangliogliomas and lesional epilepsy for this study. Forty-one (78.8%) were located in the temporal lobe, 11 (21.2%) extratemporally. Additionally to neuronavigation and intraoperative 1.5-Tesla MR imaging, we implemented DTI tractography (visual-, speech- and pyramidal tracts) in 15 and functional MRI (Wernicke's area, motor cortex) in 10 patients. Tailored resections were performed in 12 patients using intraoperative electrocorticography (ECoG).

Results: The registration accuracy of neuronavigation was 1.5 ± 0.7 mm. The first MRI scan before closing revealed complete resection of the lesion in only 31 of 52 patients (59.6%). Consequently, remnant tumour was identified in 21 patients. After re-segmentation of the residual tumour and update of neuronavigation, total resection rate was improved by 12 patients to 43/52 (82.7%). The remaining patients had subtotal resections due to the vicinity to eloquent brain structures. Follow-up was available for 37 patients to date, who showed excellent seizure control with 31/37 (83.8%) patients having an Engel Class 1 outcome (Engel 1A in 28/37 or 75.7% of all patients) after a mean time period of 60 ± 44 months. Four out of six patients with a permanent neurological deficit presented with short and long-term memory decline (7.7%), two had visual field deficits (3.8%).

Conclusions: Neuronavigation and intraoperative MR imaging increased complete resections in our series of ganglioglioma patients with medically refractory epilepsy by 20%, leading to an excellent seizure control and a low complication rate.