Radiological prognostication in patients with head trauma requiring decompressive craniectomy: Analysis of optic nerve sheath diameter and Rotterdam CT Scoring System

Introduction: Optic nerve sheath diameter (ONSD) measured on CT scan has been shown to predict outcomes of patients with severe traumatic brain injury. No such relation has been studied in patients undergoing decompressive craniectomy (DC). We evaluated ONSD on admission CT scan to predict outcomes of patients undergoing DC along with Rotterdam CT Score (RCTS). Materials and methods: This retrospective cohort study was approved by the institutional ethics committee. All the consecutive patients undergoing DC with available images and records were included. We measured ONSD 3 mm behind the eyeball and calculated RCTS. Glasgow Outcome Scale (GOS) was measured at last follow-up. We analyzed the data on SPSS v 19. Receiver operator curve analysis (ROC) was done to measure the predictive values of ONSD and RCTS for mortality and unfavorable outcomes. Results: One hundred and seventeen patients were included. Twenty patients had bilateral DC. Mean GCS at presentation was 8.5 ± 3.5. Mean follow-up was 7.5 ± 1.2 months. Thirty-day mortality was 19%. Mean ONSD of both eyes was 6.73 ± 0.89 mm. Area under the curve (AUC) for bilateral mean ONSD as predictor of mortality was 0.49 [95%CI: 0.36-0.62]. AUC for RCTS was as a predictor of 30-day mortality was significant, i.e. 0.67 [95%CI: 0.572-0.820]. The difference of mean ONSD was also not significantly different between survivor and non-survivors. Conclusion: Admission ONSD in DC patients is high but does not predict mortality and unfavorable outcomes. RCTS has a better prognostic value for predicting mortality and unfavorable outcomes in DC patients.