Decreased temporalis muscle volume is an independent risk factor for external ventricular drain-related infections

To investigate whether temporalis muscle volume (TMV), a quantitative biomarker of sarcopenia derived from routine preoperative cranial CT, is independently associated with the risk of external ventricular drain-related infection (ERI).

In this retrospective cohort study of 677 patients underwent external ventricular drain placement, TMV was quantified from preoperative cranial CT scans using a semi-automated MATLAB (Matrix Laboratory) algorithm. Patients were stratified based on sex-specific low-TMV thresholds. Multivariable logistic regression was used to determine the independent association between TMV and ERI, adjusting for relevant clinical confounders.

The incidence of ERI was 9.0% (61/677). Patients who developed ERI had a significantly lower median TMV than those who did not (14.3 cm³vs. 15.6 cm³, p < 0.001). The ERI rate was 2-fold higher in the low-TMV group (15.0% vs. 7.5%, p = 0.005). After multivariable adjustment, reduced TMV remained an independent predictor of ERI (adjusted odds ratio (OR) = 1.13, 95% confidence interval: 1.04 - 1.22). Prolonged catheter indwelling time (OR = 3.43) and intensive care unit stay (OR = 2.09) were also identified as significant risk factors.

Reduced TMV is a strong and independent risk factor for ERI. Its principal clinical advantage lies in being a readily available biomarker obtainable from existing preoperative imaging, without the need for additional scans, costs, or radiation exposure. Thus, TMV quantification represents a novel, practical, and objective tool for preoperative risk stratification, potentially guiding targeted preventive strategies in high-risk neurosurgical patients.