Temporal Muscle Thickness Compared to Functional Scales as a Prognostic Parameter in Patients with Brain Metastases

Temporal muscle thickness has become an interesting parameter in recent neuro-oncological research due to promising results regarding the estimation of patients' prognosis. The aim of our study was to assess its usefulness in terms of estimating prognosis after the surgical resection of brain metastases compared to functional scales. This research did not confirm previously published data postulating a significant influence of thicker temporal muscle on patient survival, but proved no association with better outcomes after neurosurgical therapy. Metastases are the most frequent intracranial malignant tumors in adults. While Karnofsky Performance Status (KPS) and Clinical Frailty Scale (CFS) are known to have significant impact on overall survival (OS), temporal muscle thickness (TMT) has been postulated to be a promising new parameter to estimate prognosis. Patients who received a resection of one to three brain metastases in our institution were included. Temporal muscle thickness was measured in preoperative MRI scans according to a standardized protocol. In 199 patients, the mean TMT was 7.5 mm (95CI 7.3-7.7) and the mean OS during follow-up was 31.3 months (95CI 24.2-38.3). There was no significant correlation of TMT and preoperative or follow-up CFS and KPS. While CFS and KPS did significantly correlate with OS (p < 0.001 for each), no correlation was demonstrated for TMT. CFS showed a superior prognostic value compared to KPS. TMT failed to show a significant impact on OS or patient performance, whereas the clinical scales (KPS and CFS) demonstrate a good correlation with OS. Due to its superiority over KPS, we strongly recommend the use of CFS to estimate OS in patients with brain metastases.