Article
Comparison of two different risk stratification models to predict the postoperative motor outcome in brain tumour surgery
Risikostratifizierung des motorischen Outcomes in der Hirntumorchirurgie – ein Vergleich zweier Modelle
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Published: | June 4, 2021 |
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Outline
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Objective: Brain tumor surgery near the motor cortex or the corticospinal tract bears the risk of a new postoperative paresis. Two motor outcome prediction models have been recently published. One model is based on a sum score of clinical and MR-morphological features while the other one relies on navigated transcranial magnetic stimulation (nTMS). The aim of this study was to compare two risk stratification models with respect to their prognostic value for the postoperative motor outcome.
Methods: We retrospectively analyzed a consecutive cohort of patients who underwent resection for motor eloquent glioma between 2008 and 2020, and received a preoperative nTMS examination with TMS-based DTI fiber tracking. The sum score (Spena et al. 2018) ranges from 1-8 (with lower scores indicating an increased risk) and bases on : tumor margins, volume, presence of cysts, contrast agent enhancement, MRI index (defined gradation of subcortical white matter infiltration levels), preoperative seizures, preoperative sensor-/ motor deficit. For the nTMS, the following items were assessed: infiltration of motor cortex, tumor-tract-distance, resting motor threshold. Associations to the motor outcome were evaluated postoperatively and after 3 months according to the British Medical Research Council (MRC) grading.
Results: 204 patients (75 female) with a median age of 50 years (20-81) were analyzed. 34 out of 188 patients (18%) suffered from a new permanent motor deficit, all of whom were classified as high-risk patients in the TMS stratification (sensitivity 100%), whereas only 35% of the patients with a new deficit had a low sum score (8mm: 0%; p < 0.001). The individual RMT values for each hemisphere were correlated (sick hemisphere: p = 0.009, Pearson’s r = 0.19; healthy hemisphere: p = 0.003, Pearson’s r = 0.22).
Conclusion: The functional-derived parameters of the nTMS stratification had a higher sensitivity and a higher NPV for prognostication of postoperative motor outcome compared to the clinical and MR-morphological variables of the sum score.