High-grade gliomas (HGG), recognised biologically, clinically and radiologically as the more rapidly progressive and aggressive glial cell tumours, were traditionally classified as Grade III (anaplastic astrocytoma, anaplastic oligodendroglioma and anaplastic ependymoma) or IV (glioblastoma) according to the 2007 World Health Organization (WHO) classification of central nervous system (CNS) tumours.1 However, the 2021 WHO classification (CNS5) builds on the 2016 classification and further moves towards an integrated histological and molecular diagnosis.2,3 This aims to better predict tumour behaviour, treatment response and prognosis.3

In the United Kingdom (UK), the overall statistics on the incidence of HGG are unclear. In England alone, 34 % of brain tumours diagnosed between 2006 and 2010 were astrocytomas, 80 % of which were Grade IV (glioblastoma).4 In the period between 2007 and 2011, the overall national age standardised incidence of glioblastoma was 4.64/100 000/year in England.5 As per current evidence, the UK National Institute for Health and Care Excellence (NICE) recommends that for radiologically suspected HGGs, maximal safe debulking is offered to patients as first-line treatment followed by adjuvant chemoradiotherapy.6

The aim of surgery in HGG is maximal safe debulking which is associated with best overall prognosis while preventing post-operative neurological deficits.7 Survival benefits have been reported in studies that achieve at least 70–80 % resection of the radiologically enhancing component.7, 8, 9 In addition, resection prevents false negatives due to limited tissue samples from biopsies and thus improves histological diagnosis to optimise adjuvant chemoradiotherapy.10 Although gross total resection (GTR) - defined as the complete removal of radiologically enhancing tumour - is associated with greatest increase in survival,11,12 it is often surgically challenging due to the infiltrative nature of these tumours. Maximising the extent of resection (EOR) aiming towards GTR also poses significant risks of post-operative neurological deficit, especially if the tumour is located adjacent to eloquent regions of the brain. Accordingly, onco-functional balance has been the paradigm shift in glioma surgery.13

Awake craniotomy (AC) with intraoperative cortical and subcortical mapping is preferred for maximising EOR in eloquent region without worsening neurological functions.14 A meta-analysis from 2019 of 53 studies comparing AC and intraoperative stimulation mapping versus resection under general anaesthesia (GA) in HGG surgery found significant improvement in surgical outcomes including longer overall survival (OS), lower post-operative complication rates and higher percentage of GTR.15 Since then, several other meta-analyses have also demonstrated favourable outcomes for AC.16,17 Of note, a meta-analysis investigating outcomes of AC for resection of supratentorial glioblastoma demonstrated a GTR rate of 74.7 % and a low rate of persistent neurological deficits (1.9 %).17 Furthermore, intraoperative mapping in AC has also made resection feasible in cases where gliomas were deemed radiologically “inoperable”.18 The UK NICE guidance for management of glioma recommends that AC is discussed with patients provided that they are unlikely to be significantly distressed by the prospect.6

Studies to date from the UK reporting on AC include a heterogenous group of patients with low- and high-grade gliomas and/or other intracranial tumours.19, 20, 21, 22 This limits the evaluation of surgical outcomes and the true impact of AC in HGG patients. Therefore, this study aims to report solely the experience and outcomes of AC for HGG surgery from our centre.