Speakers

Diamond knife dissection technique for cochlear and facial nerve preservation during resection of vestibular schwannomas (VS).
1108 08:30-08:40
Skull Base/304A
Introduction: Facial and cochlear nerve preservation is a major effort, especially in large vestibular schwannomas. Bimanual dissection techniques using pincers or plate knifes have been found as a crucial step for hearing preservation and avoiding facial palsy. We investigated a newly described technique using a diamond knife for nerve dissection during VS removal. Methods: A retrospective investigation including 61 VS patients during a periode of 3.5 years was performed comparing plate-knife and diamond knife dissection during tumor removal. Altogether, 51 patients were operated using the standard plate knife technique (52yrs mean age, tumor diameter mean 20 mm) and 10 patients were operated using the diamond knife technique (46 yrs mean age, mean tumor diameter 22 mm). Results: In the standard group, postoperative useful hearing preservation was achieved in 45% and permanent facial nerve palsies detected in 9.8%. On the contrary, in the diamond knife dissection group postoperative hearing preservation was found in 70% und permanent facial nerve palsies in 0% (differences highly significant). In both groups complete resection was found in 84% and 90%, small tumor residuals on the facial nerve (small postop linear MRI enhancement) found in 16% and 10%. Conclusion: The newly described diamond knife dissection technique seems to have a significant better hearing outcome and facial nerve preservation rate in otherwise comparable patients during surgery of vestibular schwannomas.

Seizure outcome in surgically treated pediatric gangliogliomas and dysembrioplastic neuroepitheliomas according to imaging and resection strategies.
1109 09:07-09:22
Interim Meeting of AASPN/303A
Introduction: Imaging and resection strategies for pediatric gangliogliomas (GG) and dysembrioplastic neuroepitheliomas (DNET) presenting with epilepsy were retrospectively analyzed in a consecutive institutional series of surgically treated patients. Methods: Twenty-two children (median 8 years, 3-12.8 years) presented with seizures for 30 months median (14-55.2 months) due to histologically verified GG/DNET. Results: There were 20 GG and 2 DNT, 68% located temporal, 32% extra-temporal. Seizure history was significantly longer in temporal cases (38 versus 14 months median, p<0.01). MRI contrast enhancement was present in 50% and methionine (MET) PET (positron emission tomography) uptake in 70% (standard uptake values (SUVs) 2.92 mean, from 1.6 to 6.4). 27% had glucose PET hypometabolism. Primarily, in temporal GG, ECoG-guided lesionectomies were performed in 87% and temporal lobe resections (TLR) in 13%, whereas in extra-temporal GG/DNETs, lesionectomies were performed in 100%. ILAE Class 1 seizure outcome was primarily achieved in 73% of the temporal cases, which could be increased to 93% by performing six repeat surgeries using TLR. Extratemporal patients primarily experienced ILAE Class 1 seizure outcomes in 86% without additional surgeries, although harboring significantly more residual tumors (p<0.005, mean follow-up 28 months). Conclusion: In children, MET PET imaging for suspected GG is proposed preoperatively showing a high diagnostic sensitivity and an option to delineate the lesions during navigated resection, whereas MRI contrast behavior is of no differential diagnostic use. As a surgical strategy we propose primarily lesionectomies for extratemporal but TLR for temporal GG presenting with epilepsy respecting eloquent brain areas.

Continuous facial corticobulbar motor evoked potentials (FCoMEP) monitoring during vestibular schwannoma surgery to avoiding permanent facial palsy.
1108 13:30-13:40
Skull Base/304A