Article
TMS recruitment curve and cortical silent period analysis – a sensitive tool to detect imminent motor deficits in brain tumour patients
TMS-Rekrutierungskurve und Analyse der kortikalen Innervationsstille – sensitive Parameter zur Erkennung bevorstehender motorischer Defizite bei Hirntumorpatienten
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Published: | June 26, 2020 |
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Objective: One of the challenges of tumor resection in motor eloquent areas is the individual risk assessment for a postoperative motor disorder. Previously, a predictive model was developed that permits objective evaluation of the risk prior to surgery based on topographical and neurophysiological data, derived from an investigation with navigated transcranial magnetic stimulation (nTMS). The aim of this study is the improvement of the prognostic power of the aforementioned model by inclusion of additional neurophysiological parameters.
Methods: Prospective data from 170 patients with malignant glioma in motor eloquent areas was collected and further investigated by topographical and neurophysiological nTMS parameters: Resting Motor Threshold (RMT), Recruitment Curve (RC) and Cortical Silent Period (CSP) bi-hemispherically prior to surgery. Motor function was quantified according to the British Medical Research Council Scale preoperatively as well as seven days and three months postoperatively.
Results: The univariate analysis confirmed the RMT ratio’s predictive value (p=0.008) for the postoperative motor outcome after seven days with an increased number of patients. An association between a pathological CSP ratio and development of a new postoperative motor deficits after seven days was observed (p=0.025). A pathological RC Ratio was significantly associated with the preoperative motor status (p=0.019) as well as the postoperative deterioration of motor function after three months (p=0.003). Multiple regression analysis concluded that an abnormal RMT ratio was significantly associated with motor worsening in high risk patients after seven days.
Conclusion: To conclude, the present study was able to confirm an existing risk-stratification model for patients with motor eloquent brain tumors. RMT ratio is the most important distinguished predictor in the tractography based "high-risk group" for the postoperative motor outcome. Further, we identified a disturbed RC ratio as specific predictor for long-term motor impairments after surgery,compared to the RMT and CSP indexing short-term deficits.