Assoziation von Veränderungen des intraoperativen Neuromonitorings bei Resektion von Inselgliomen mit sensomotorischen Defiziten im Langzeitverlauf

This study aimed at analyzing the predictive value of intraoperative neurophysiological monitoring (IONM) changes in insular glioma surgery and their association with long-lasting postoperative sensorimotor deficits.

Clinical charts of 42 patients undergoing 44 tumor resections with IONM were reviewed. Significant changes in motor evoked potentials (MEP) and somatosensory evoked potentials (SSEP) were defined as a reduction in the respective amplitudes by more than 50% as compared to the initial measurements at dura opening. Changes were classified as "temporary" if they restored to above 50% and "permanent" if they remained below 50% at the time of dura closure. Postoperative MRI was performed within 72 h after surgery. Sensitivity and specificity of IONM-changes as well as the relative risk (RR) for developing a permanent sensorimotor deficit were calculated. Logistic regression was used to assess the association of IONM changes with the Berger-Sanai zone and territorial ischemia on postoperative MRI.

The median age of the cohort was 43 years (IQR 34–51). Approximately one-third of patients had tumors located in the left insula with the most frequent localization within the insular Zone I. The overall rate of postoperative new neurological deficits at 3-months follow-up was 13.6%. Permanent significant MEP and SSEP changes demonstrated a sensitivity and specificity of 83% and 97.3% respectively to predict a sensorimotor deficit at 3-months follow-up. The RR of those patients for developing a permanent neurological deficit was 26.43 (95% CI 4.664-154.6; p=0.0001). Permanent significant IONM were more frequent during resection of giant insular gliomas (invading zones I-IV), although this finding did not reach statistical significance (OR 3; 95%CI 0.445-25; p=0.259). Additionally, significant MEP and SSEP changes were strongly associated with territorial ischemia on postoperative MRI (OR 8.250; 95%CI 1.146-73.97; p=0.038). Notably, temporary MEP decreases occurred in four patients, none of them exhibited a permanent sensorimotor deficit at 3 months follow-up evaluation.

In our study, permanent significant IONM changes (but no transient IOM findings) were associated with permanent sensorimotor deficits at the 3-month follow-up, partially due to territorial ischemia. These findings highlight the value of IONM in predicting postoperative sensorimotor deficits in insular glioma surgery.