Reduced temporal muscle thickness predicts shorter survival in patients undergoing chronic subdural haematoma drainage.

Abstract

Chronic subdural haematoma (CSDH) drainage is a common neurosurgical procedure. CSDHs cause excess mortality, which is exacerbated by frailty. Sarcopenia contributes to frailty - its key component, low muscle mass, can be assessed using cross-sectional imaging. We aimed to examine the prognostic role of temporal muscle thickness (TMT) measured from preoperative computed tomography head scans among patients undergoing surgical CSDH drainage. We retrospectively identified all patients who underwent CSDH drainage within 1year of February 2019. We measured their mean TMT from preoperative computed tomography scans, tested the reliability of these measurements, and evaluated their prognostic value for postoperative survival. One hundred and eighty-eight (122, 65% males) patients (median age 78years, IQR 70-85years) were included. Thirty-four (18%) patients died within 2years, and 51 (27%) died at a median follow-up of 39months (IQR 34-42months). Intra- and inter-observer reliability of TMT measurements was good-to-excellent (ICC 0.85-0.97, P<0.05). TMT decreased with age (Pearson's r=-0.38, P<0.001). Females had lower TMT than males (P<0.001). The optimal TMT cut-off values for predicting two-year survival were 4.475mm for males and 3.125mm for females. TMT below these cut-offs was associated with shorter survival in both univariate (HR 3.24, 95% CI 1.85-5.67) and multivariate (HR 1.86, 95% CI 1.02-3.36) analyses adjusted for age, ASA grade and bleed size. The effect of TMT on mortality was not mediated by age. In patients with CSDH, TMT measurements from preoperative imaging were reliable and contained prognostic information supplemental to previously known predictors of poor outcomes.