Does optic nerve sheath diameter predict early or late mortality in severe traumatic brain injury treated with primary decompressive craniectomy?

Optic nerve sheath diameter (ONSD) has been proposed as a noninvasive marker of elevated intracranial pressure (ICP) in traumatic brain injury (TBI). However, its prognostic value in patients undergoing primary decompressive craniectomy (DC) remains uncertain, particularly in the absence of preoperative ICP monitoring. This study aimed to examine whether preoperative ONSD correlates with early or late mortality following primary DC. This retrospective cohort study included 201 TBI patients who underwent primary DC. After exclusions, 169 patients were analyzed for short-term mortality, defined as in-hospital death, and 150 for long-term outcomes, defined as survival status at the last clinical follow-up beyond 12 months. Preoperative ONSD was measured on axial non-contrast computed tomography (CT) scans. Associations between ONSD and mortality were assessed using logistic regression and Kaplan–Meier analysis. The in-hospital mortality rate was 29.6%, and the long-term mortality rate was 44.0%. Regression models were adjusted for established post-DC prognostic variables, including age, Glasgow Coma Scale score, Injury Severity Score, pupillary reactivity, and the Rotterdam CT score. Although mean ONSD was modestly higher among non-survivors, neither univariate nor multivariate models demonstrated a statistically significant association with short- or long-term mortality. Likewise, survival analyses using a 6 mm ONSD threshold revealed no significant differences (short-term p = 0.13; long-term p = 0.61). In conclusion, among patients undergoing primary DC for TBI, preoperative CT-based ONSD does not independently predict mortality. These findings suggest that ONSD alone may have limited prognostic utility in this high-risk population.