Post-operative morbidity ensuing surgery for insular gliomas: a systematic review and meta-analysis

The surgical resection of insular gliomas remains a challenge. Middle cerebral artery perforating arteries and deep functional pathways affect the extent of resection and the rate of post-operative morbidity. The authors performed a systematic review and meta-analysis of the literature examining early and permanent post-operative deficits in patients who underwent resection of insular gliomas using awake craniotomy with direct electrical stimulation (DES) versus surgery under general anesthesia. A systematic search of three databases was performed for studies published between 1990 and 2018. Random-effect meta-analysis was used to pool the rate of early and permanent post-operative deficits. Random-effect meta-regression was used to examine the association between the rate of post-operative deficit and the anesthesia protocol. We included eight studies evaluating 227 patients with insular glioma. The rate of permanent sequelae was lower after awake craniotomy with DES (3.5% vs 15.7%; P =.001), and early deficits were lower after surgery under general anesthesia (27.3% vs 47.7%; P =.04). Awake surgery was significantly more common among patients with tumor located within the dominant hemisphere (P <.001). No significant association arose between the rates of post-operative deficits and the use of intraoperative neuronavigation and the neurophysiological monitoring. Furthermore, neither extent of resection nor tumor histology influenced the onset of permanent sequelae. Awake craniotomy with DES is associated with a significantly lower rate of permanent neurological morbidity after an early increase of transient post-operative deficits. These data support the use of awake mapping in insular glioma resection.