Brain surgery of infiltrative gliomas aims to balance tumor removal with preservation of functional integrity. The usefulness of intraoperative stimulation mapping (ISM) has not been addressed in randomized trials.

     This study addresses the impact of ISM on glioma surgery outcome based on a meta-analysis of observational studies.

     A systematic search retrieved 90 publications published between 1990 and 2010 with 8,091 adult patients who had resective surgery for supratentorial infiltrative glioma, either with or without ISM.

     Quality criteria consisted of details of postoperative neurological examination and follow-up timing. New postoperative neurological deficits were categorized based on timing and severity. The summary event rates of neurological deficits were determined by meta-analysis with a Bayesian random effects model, as well as percentages of gross total resections and eloquent locations. Meta-regression analysis explored sources of heterogeneity between studies.

     Late severe neurological deficits were observed in 3.4% (2.3-4.8%) of 3,230 patients after resections with ISM, and in 8.2% (5.7-11.4%) of 1,731 patients after resections without ISM. The percentage of radiologically confirmed gross total resections was 75% (66-82%) with ISM and was 58% (48-69%) without ISM. Eloquent locations were involved in all 99.9% (99.9-100%) resections with ISM and in 95.8% (73.1–99.8%) of resections without ISM. Relevant sources of heterogeneity between studies were ISM, North American or European continent and academic study setting.

     This is a literature review and analysis.

     Glioma resections utilizing ISM are associated with less late severe neurological deficits.  

     Without compromising the extent of resection and while involving eloquent locations more frequently.