Evaluation of bedside sonographic measurement of optic nerve sheath diameter for assessment of raised intracranial pressure in adult head trauma patients

Aim: The aim was to evaluate the use of bedside sonographic measurement of the optic nerve sheath diameter (ONSD) in the assessment of elevated intracranial pressure in patients with head injury coming to the emergency department (ED). Methods: A prospective study of ED patients presenting with a history of acute head injury, an ocular ultrasound was performed for ONSD measurement, followed by a computed tomography (CT) of the brain. Three measurements were taken for each eye, then, the mean binocular ONSD measurement for each patient was obtained to ensure accuracy. A mean bipolar ONSD >5 mm was considered abnormal. Results: A total of 175 patients were considered for the study. Of 175 patients, only 56 (32%) had intracranial pathology detected on CT brain with mean ONSD of 5.7 mm (standard deviation [SD]: 0.59). The mean ONSD for 119 (68%) patients, who had normal CT brain, was 4.5 mm (SD: 0.42). The mean ONSD measured for the right eye was 4.86 mm with SD 0.88, and the mean ONSD for the left eye was 4.90 mm with SD 0.85. When comparing ONSD measurement with CT findings of raised intracranial pressure, the ONSD sensitivity was 87.5% (95% confidence interval [CI]: 85%-96%) and specificity was 94.1% (95% CI: 85%-96%), with a positive predictive value of 87.5% and a negative predictive value of 94.1%. The area under the receiver operator characteristic curve obtained was 0.90 (95% CI: 0.85-0.96). Conclusion: The study has shown a bedside measurement of ONSD through sonography as an efficient tool to assess elevations in intracranial pressure in head injury patients.