Intracranial pressure assessment in traumatic head injury with hemorrhage via optic nerve sheath diameter.

Our purpose was to improve the technique of measuring optic nerve sheath diameter (ONSD) for intracranial pressure (ICP) monitoring in cases of traumatic head injury with hemorrhage. In a retrospective study, computed tomography (CT) data of 312 adult patients were collected and analyzed. ONSDs were measured at 3mm and 8-10mm distance from the globe together with the eyeball transverse diameter (ETD). The ONSD/ETD ratio was calculated. The correlation analysis was performed with gender, age, Glasgow Coma Scale score, and Glasgow Outcome Score. ONSD was enlarged in all cases when CT scans indicated hematoma. Enlarged right/left ONSDs were 6.5 +/- 1.5/6.4 +/- 1.3 mm at 3 mm and 6.6 +/- 0.8/6.6 +/- 0.6 mm at 8-10 mm from the globe (cut-off value >5.5 mm). ONSD/ETD ratio was 0.29 +/- 0.05, compared with 0.19 +/- 0.02 in healthy adults (p < 0.01). We did not find a correlation between ONSD/ETD ratio and initial Glasgow Coma Scale score, but there was an inverse correlation between ONSD/ETD ratio and Glasgow Outcome Score (r = -0.83). We conclude that in cases with a traumatic head injury with hemorrhage, the ONSD is significantly enlarged, indicating elevated ICP. In ICP assessment, the most accurate results can be obtained if the ONSD is measured 8-10 mm from the globe and the ONSD/ETD ratio is calculated.