Temporal Muscle Thickness Correlates with Sarcopenia in Parkinson's Disease

Background: Sarcopenia is characterized by a progressive loss of muscle mass, strength, and function resulting in adverse health outcomes. Current assessment strategies are bothersome and means to simplify the diagnosis are an unmet medical need in Parkinson's disease (PD). Objective: To evaluate temporal muscle thickness (TMT) obtained on routine cranial MRI as a surrogate marker of sarcopenia in PD patients. Methods: We correlated TMT from axial non-contrast-enhanced T1-weighted sequences of MRI close (+/- 12 months) to an outpatient visit including sarcopenia (EWGSOP1, EWGSOP2, SARC-F), frailty (Fried's criteria, clinical frailty scale), and disease characteristics of Parkinson's patients (Hoehn and Yahr-scale, Movement Disorder Society-Unified Parkinson's Disease Rating Scale, quality of life with the Parkinson's Disease Questionnaire-8) assessments. Results: Cranial MRI was available in 32 patients with a mean age of 73.56 +/- 5.14 years, mean disease duration of 11.46 +/- 5.66 years, and median Hoehn and Yahr stage of 2.5. The mean TMT was 7.49 +/- 2.76 (7.15) mm. Mean TMT was significantly associated with sarcopenia (EWGSOP2, p = 0.018; EWGSOP1, p = 0.023) and frailty status (physical phenotype; p = 0.045). Moreover, there were significant moderate to strong correlations between TMT measurement and appendicular skeletal muscle mass index (r: 0.437, p = 0.012), as well as handgrip strength (r: 0.561, p < 0.001). Conclusion: Reduced TMT seems to be a promising surrogate marker for sarcopenia (EWGSOP2) and muscle strength in this pilot study in PD patients.