Article
Preoperative diagnostics of insular gliomas by navigated Transcranial Magnetic Stimulation (nTMS) and DTI-Tractography
Präoperative Diagnostik mittels Navigierter Transkranieller Magnetstimulation und DTI-Traktographie bei Patienten mit Inselgliomen
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Published: | May 25, 2022 |
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Objective: The operative resection of insular gliomas poses a risk of permanent hemiparesis and aphasia of up to 10%. Through navigated transcranial magnetic stimulation (nTMS) and nTMS-based DTI-tractography motor eloquent brain areas can be identified, and the motoric tracts visualized preoperatively. The aim of the study was to evaluate to what extent neurophysiological nTMS-parameters and diffusion parameters, such as the fractional anisotropy (FA) and apparent diffusion coefficient (ADC), can be used preoperatively to assess the risk of postoperative motoric deficits (PMD).
Methods: We conducted a retrospective data analysis of 20 patients who underwent a bihemispheric nTMS-examination preoperatively and had a complete record of their pre- and postoperative motor status. A nTMS-based DTI-tractography was performed to extract the average and peritumoral values of the diffusion parameters FA and ADC as well as assess the distance between the tumour and the corticospinal-tract (CST).
Results: The distance between the tumour and CST ≤ 1mm was identified as critical as it was associated with a new PMD (p = 0,007). A tumour-CST-distance of ≤ 3mm altered the peritumoral FA (pFA) and ADC (pADC) values (p = 0,045 resp. p = 0,024) and the interhemispheric pFA and pADC ratio showed an association with a PMD (p = 0,017 resp. p = 0,012). Furthermore, the interhemispheric pFA ratio could predict the postoperative motor status (RR = 0,205; p = 0,049).
Conclusion: These findings offer a relevant benefit for perioperative risk stratification, operative planning and intraoperative neuromonitoring in patients with insular gliomas.