O5.08INTRA-OPERATIVE NEUROPHYSIOLOGICAL MONITORING AND SMALL CRANIOTOMIES: RESULTS IN A CONSECUTIVE SERIES OF 85 PATIENTS WITH BRAIN TUMORS

INTRODUCTION: Intra-operative neurophysiological monitoring and brain mapping techniques represent nowadays the gold standard for surgical resection of brain tumors. Brain mapping usually requires the exposure of a large area of brain cortex in order to identify the different eloquent sites (e.g. primary motor strip, speech arrest sites). Thus, relatively large classic fronto-temporal craniotomies are generally performed. Nevertheless, in recent years the use of small craniotomies targeted on the tumor has gained popularity thanks to Neuronavigation systems and to the low morbidity rates associated with shorter surgical procedures and reduced anesthestic drug administration. Aim of this study was to review our experience which combines extensive neurophysiological monitoring and small craniotomies. Length of surgical time, intra-operative and post-operative complications, length of stay, extent of resection rate and the neurological outcomes were assessed. PATIENTS AND METHODS: Eighty-five consecutive patients (54 Males, 31 Females; Median Age 55 years, range 12-77) underwent surgery with brain mapping and intra-operative neurophysiological monitoring for resection of a brain tumor in eloquent location under asleep-asleep (62 patients) or asleep-awake (23 patients) anesthesia. Pre- and post-operative assessment included in-depth neuropsychological evaluation and MRI. Tumor histologies were the following: 74 gliomas (60 HGG, 14 LGG), 6 metastases and 5 other tumor histologies (2 cavernomas, 2, meningiomas, 1 AVM). The bone flap was tailored to the size of the tumor; no cortex other than that which was strictly necessary for tumor resection was exposed. The intra-operative neurophysiological monitoring included: EEG, SSEP, transcranial MEP and/or cortical MEP, ECoG; direct electrical stimulation (DES) was performed using bipolar and monopolar probes. RESULTS: Median surgical time was 230 minutes (range 90-390). Intra-operative complications included 9 seizures (3 requiring pharmacological treatment, 6 regressing after cold irrigation) and 5 electrical seizure. Post-operative neurosurgical complications were the following: 8 seizures and 4 re-operation for hematoma. Seventy-three patients (86%) could be discharged home while 12 (14%) were transferred to rehabilitation. In only 3 patients (3.5%) a permanent new neurological deficit could be noted at 3-month follow-up. Median post-operative stay was 7 days (range 3-45). CONCLUSIONS: In our experience a small craniotomy supported by extensive neurophysiological monitoring and brain mapping permitted to achieve satisfactory results in terms of complications, hospitalization, and neurological outcomes.