The Value of Diffusion Tractography for Awake Surgery

Abstract

Abstract AIMS Despite evidence of correspondence with intraoperative stimulation, there remains limited data on MRI diffusion tractography (DT)’s sensitivity to predict morbidity after brain tumour resection. Our aims were: (1) evaluate DT against subcortical stimulation mapping and performance changes during and following awake surgery; (2) evaluate the use of early post-operative DT to predict recovery from post-surgical deficits. METHOD We performed a retrospective review our first 100 awake neurosurgery procedures using DTneuronavigation. Intra-operative stimulation and performance outcomes were assessed to classify DT predictions for sensitivity and specificity calculations. RESULTS Between 2014 and 2019 a total of 91 adult brain tumour patients (mean age 49.2 years) underwent 100 awake surgeries with subcortical stimulation. The sensitivity and specificity of pre-operative DT predictions were 92.2% and 69.2%, varying among tracts. Post-operative deficits occurred after 41 procedures (39%), but were prolonged (>3 months) in only 4 patients (4%). Post-operative DT was available in 51 patients and confirmed surgical preservation of tracts. Post-operative DT anticipated complete recovery in a patient with supplementary motor area syndrome, and indicated infarct-related damage to corticospinal fibers associated with delayed, partial recovery in a second patient. CONCLUSION Pre-operative DT provided very accurate predictions of the spatial location of tracts in relation to a tumour. As expected, however, the presence of a tract did not provide information on its functional status, resulting in variable DT specificity among individual tracts. While prolonged deficits were rare in our series, DT in the immediate post-operative period offered additional information to monitor neurological deficits and anticipate recovery potential.