Diffusion MRI Tractography to Reduce Risks of Postoperative Neurologic Deficits: A Systematic Review and...

Despite informing on the location of functionally relevant white matter tracts, diffusion MRI tractography is not routinely used to guide neurosurgical procedures. The potential of tractography to help avoid postoperative neurologic deficits is not yet fully established. The objective of our study was to assess whether surgeries that incorporated tractography, either alone or in conjunction with other modalities, are associated with a lower risk of long-term postoperative neurologic deficits in patients undergoing resective/ablative intracranial procedures.

We performed a systematic review with meta-analysis, searching through EMBASE and PubMed databases for all peer-reviewed articles published in English up until December 2024. Studies were included if they reported on intracranial resective or ablative surgeries, if they compared tractography-assisted against non-tractography-assisted approaches, and if they assessed new postoperative neurologic deficits. No restrictions were placed on the age of patients. Studies were assessed for inclusion by 2 independent reviewers, and disagreements were settled by a third. Data extraction was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, quality of studies was evaluated using the GRADE framework, and risk of bias was assessed through a modified version of the Newcastle-Ottawa Quality Assessment Scale for Cohort Studies. Data were pooled using a random-effects model with a Mantel-Haenszel method for estimating risk ratios. The primary outcome consisted in any neurologic deficits present at the last follow-up (≥3 months).

Of 5,335 studies initially identified, 8 were included after all stages of review, all of which consisted of resective surgeries. A meta-analysis of 629 patients revealed a 55% risk reduction of postoperative neurologic deficits when tractography was incorporated in the neurosurgical workflow. This benefit was consistent when assessing studies where tractography was exclusively used preoperatively. Furthermore, the incorporation of tractography into intraoperative neuronavigation systems was associated with lower proportions of postoperative neurologic deficits, compared with exclusively preoperative tractography. These benefits were found to be present in several additional subgroup and sensitivity analyses.

The addition of tractography is associated with a reduced risk of postoperative neurologic deficits in intracranial resective surgeries. Tractography can complement gold standard brain mapping methods such as direct electrical stimulation during awake surgeries or serve as a helpful alternative when electrical stimulation is contraindicated.