Article
TMS recruitment curve and cortical silent period analysis: a sensitive tool to detect imminent motor deficits in brain tumor patients
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Authors
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Ina Bährend
- Charité - Universitätsmedizin Berlin, Klinik für Neurochirurgie, Berlin, Deutschland
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Tizian Rosenstock
- Charité - Universitätsmedizin Berlin, Klinik für Neurochirurgie, Berlin, Deutschland
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Anna Zdunczyk
- Charité - Universitätsmedizin Berlin, Klinik für Neurochirurgie, Berlin, Deutschland
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Heike Schneider
- Charité - Universitätsmedizin Berlin, Klinik für Neurochirurgie, Berlin, Deutschland
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Ulrike Grittner
- Charité - Universitätsmedizin Berlin, Biostatistik und klinische Epidemiologie, Berlin, Deutschland
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Vera Schwarzer
- Charité - Universitätsmedizin Berlin, Klinik für Neurochirurgie, Berlin, Deutschland
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Peter Vajkoczy
- Charité - Universitätsmedizin Berlin, Klinik für Neurochirurgie, Berlin, Deutschland
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Thomas Picht
- Charité - Universitätsmedizin Berlin, Klinik für Neurochirurgie, Berlin, Deutschland
| Published: | June 18, 2018 |
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Outline
Text
Objective: This study aims to improve the prognostic power of the previously described nTMS-based risk-stratification model for surgery of motor area related brain tumors. The current input variables of the model are:
- 1.
- presence of infiltration of the primary motor cortex by the tumor,
- 2.
- the minimal distance of the tumor to the corticalspinal tract and
- 3.
- the ratio of the bihemispheric resting motor threshold (RMT).
The aim of this study is the improvement of the aforementioned model by including additional neurophysiological parameters: Recruitment Curve (RC) and Cortical Silent Period (CSP).
Methods: nTMS was used to map the cortical motor representation area of the FDI muscle in 165 patients with malignant gliomas in presumed motor eloquent areas prior to surgery. In addition to the established variables, the Recruitment Curve (RC) and the Cortical Silent Period (CSP) were analyzed. Each metric was measured bihemispherical. The motor function was assessed according to the British Medical Research Council Scale preoperatively and postoperatively after seven days and three months.
Results: In respect to the postoperative motor outcome after seven days, the RMT Ratio’s predictive value was confirmed (p=0,002). Yet, in respect to the postoperative motor outcome after three months no significant correlation could be found (p=0.4). For the CSP Ratio a correlation to the preoperative motor status was observed (p=0.04). Patients with moderate and severe paresis demonstrated a significant prolonged CSP latency compared to patients without paresis. A tendency towards an increased presurgical cortical GABAergic inhibition in patients with new postoperative deficits was recognizable, but it was not significant. For the presurgical RC Ratio on the other hand, a significant correlation to the preoperative motor status (p=0.001) as well as for postoperative deterioration of motor function after three months was found (p=0.03).
Conclusion: Addition of the RC Ratio significantly improved the value of the nTMS based predictive model, since the RC Ratio allows for prediction of new motor deficits 3 month after surgery. Addition of the CSP Ratio on the other hand did not, based on the current analysis, add predicitve power to the model. The predictive power of the previously established correlation between presurgical RMT Ratio and motor status on day 7 was improved based on the larger study sample.
