The clinical and prognostic values of optic nerve sheath diameter and optic nerve sheath diameter/eyeball transverse diameter ratio in comatose patients with supratentorial lesions

Background The optic nerve sheath diameter (ONSD) and ONSD/eyeball transverse diameter (ETD) ratio have been proven to be correlated with intracranial pressure. This study aimed to evaluate the prognostic roles of ONSD and the ONSD/ETD ratio in comatose patients with supratentorial lesions and to determine the relationship of these two indices with the prognosis of such patients. Methods A total of 54 comatose patients with supratentorial lesions and 50 healthy controls were retrospectively included in this study. ONSD and ETD were measured by unenhanced computed tomography (CT). The differences in ONSD and the ONSD/ETD ratio between the two groups were compared. The prognosis of comatose patients was scored using the Glasgow Outcome Scale (GOS) at the 3-month follow-up, and these patients were classified into good (GOS score >= 3) and poor (GOS score < 3) prognosis groups. The differences in ONSD and the ONSD/ETD ratio were compared between comatose patients with good prognoses and those with poor prognoses. Results The ONSD and ONSD/ETD ratios in the comatose patients were 6.30 +/- 0.60 mm and 0.27 +/- 0.03, respectively, and both were significantly greater than those in the healthy controls (5.10 +/- 0.47 mm, t = 11.426, P < 0.0001; 0.22 +/- 0.02, t = 11.468, P < 0.0001; respectively). ONSD in patients with poor prognosis was significantly greater than that in patients with good prognosis (6.40 +/- 0.56 vs. 6.03 +/- 0.61 mm, t = 2.197, P = 0.032). The ONSD/ETD ratio in patients with poor prognosis was significantly greater than that in patients with good prognosis (0.28 +/- 0.02 vs. 0.26 +/- 0.03, t = 2.622, P = 0.011). The area under the receiver operating characteristic (ROC) curve, used to predict the prognosis of comatose patients, was 0.650 (95% confidence interval (CI): 0.486-0.815, P = 0.078) for ONSD and 0.711 (95% CI: 0.548-0.874, P = 0.014) for the ONSD/ETD ratio. Conclusions The ONSD and ONSD/ETD ratios were elevated in comatose patients. The ONSD/ETD ratio might be more valuable than ONSD in predicting the prognoses of comatose patients with supratentorial lesions.