Preliminary experience in Awake Surgery:Functional recovery profile

Abstract

Background. Until the advent of new exploration techniques: functional magnetic resonance imaging (fMRI) and surgical protocols such as exeresis in awake mode, the functional recovery potential of postoperative deficits was limited by conventional tumor surgery. The use of these methods simultaneously improves the quality of life and survival medians, mainly for removing low-grade gliomas massively infiltrating subcortical networks in eloquent regions where surgery is historically not associated with high functional recovery rates. Accordingly, the results from the awake brain surgery literature motivate us to establish a new baseline on the relationship between electrical stimulation mapping (ESM) threshold, the extent of resection (EOR), neuroplastic typology, and functional recovery after intraoperative crises or postoperative care deficits using induced neuroplasticity. Materials and patients. This is a retrospective analytical study of 35 brain tumor cases of gliomas, operated by common craniotomy in awake conditions from September 2016 to July 2022. Before entering awake resection mode, all patients underwent brain mapping (ESM) by direct electrical stimulation (DES) according to standard conditions and Helsinki ethical guidelines. Analysis according to ESM was done for two groups (group 1 and group 2) of different intensities of DES. Outcomes. The ESM by threshold intensity expressed in mean ± deviation standard was: 2,45 ± 0.125 mA for sensorimotor functions against 1.35 ± 0.175 mA for cognitive mapping. These stimulation currents were optimum thresholds which allowed us during control mapping to overcome all boundary conditions, mostly false negative results. The functional recovery time (FRT) following stimulation-induced seizures was varied from 2 s to 6.26 s, marking the intraoperative neuroplasticity operated mainly by synaptic remodeling during the functional reactivation. The EOR was better for group 1 with 82.35 % gross total resection (GTR) with only 8.75% of the occurrence of transient seizures against 45.7% for group 2 and only 2.86% suffered from neurological permanent deficits in group 1 against 11.42% in group 2. Conclusions. ESM in the range of [2.35 - 2.45 mA] improved DES sensitivity without false negatives. We had a compromise of improved results between these stimulation thresholds, the duration of the craniotomy, the functional recovery time, the EOR and overall the occurrence of neurological deficits, which explain the processes involved in the success of awake surgery.