Dynamic Changes in Optic Nerve Sheath Diameter on Computed Tomography Predict Decompressive Efficacy and Outcomes in Severe Traumatic Brain Injury.

Elevated intracranial pressure (ICP) is a major determinant of secondary injury and mortality in severe traumatic brain injury (TBI), yet objective markers of decompressive craniectomy (DC) efficacy remain limited. Optic nerve sheath diameter (ONSD), measurable on computed tomography (CT), has emerged as a non-invasive surrogate of ICP. This study evaluated the relationship between perioperative ONSD changes and clinical and surgical parameters in patients undergoing DC. In this retrospective cohort study, 72 patients with severe TBI were included. ONSD was measured on preoperative and early postoperative CT, and the change (ΔONSD) was analyzed in relation to craniectomy surface area and outcomes. DC resulted in a significant reduction in ONSD (6.44 ± 0.88 mm vs. 5.55 ± 0.82 mm, p < 0.001). Larger craniectomy surface areas were associated with greater ΔONSD change (r = -0.31, p = 0.008). ΔONSD was independently associated with in-hospital mortality (OR = 0.12, p = 0.005), with larger reductions associated with improved survival. Additionally, ΔONSD was correlated with shorter hospital stay (ρ = -0.32, p = 0.007). These findings support ΔONSD as a practical imaging biomarker reflecting the physiological response to DC in severe TBI.