Validation of optic nerve sheath diameter as a bedside noninvasive tool in comparison with lumbar puncture opening pressure in patients suspected of elevated intracranial pressure

Abstract

Objective The aim was to assess the diagnostic accuracy of optic nerve sheath diameter (ONSD) compared with lumbar puncture opening pressure (LPOP) and computed tomography in diagnosing elevated intracranial pressure (ICP) for critically ill patients. Moreover, the study evaluated the diagnostic ability of ONSD as a screening test for cerebral edema.Background Recently, linear relationships have been detected between ICP and ONSD, proposing ultrasound measurements as a possible noninvasive method.Patients and methods The authors performed a prospective study that included 50 patients with disturbed consciousness of unknown etiology, who were admitted to the ICUs at Beni-Suef University hospital during the period from September 2017 to September 2019. ONSD was measured by ultrasonography.Results Measurement of the right ONSD was 0.62±0.084 cm, whereas measurement of the left ONSD was 0.61±0.083 cm. The mean of two eyes was 0.61±0.09 cm, and the LPOP was 19.96±4.69 cmH2O. Overall, 36 (72%) patients had ONSD greater than 0.6 cm. Besides, 31 (62%) patients had LPOP greater than 20 cmH2O. There was a significant positive correlation between average ONSD and LPOP. Receiver operating characteristic (ROC) curve showed that ONSD greater than 0.6 cm had a diagnostic value of elevated ICP with an area under the curve of 0.872 (95% confidence interval: 0.646–0.936) with a sensitivity of 95% and specificity of 77%, with P-value of 0.001. ROC curve analysis was used for prediction of increased ICP using average ONSD compared with CT where the ROC curve showed that ONSD greater than 0.6 cm had a diagnostic value with an area under the curve of 0.606 (95% confidence interval: 0.51–0.72) with a sensitivity of 83% and specificity of 56%, with P-value of 0.028.Conclusions ONSD is significant in prediction of elevated ICP, with a good positive correlation with LPOP as a gold standard reference.