Open AccessObjective: The purpose of this study was to determine if the ONSD can be measured on digital images obtained by routine CT investigations of the brain, to identify patients with non-traumatic causes of elevated ICP, and to provide the observer with a non-invasive, objective measurement to predict elevated ICP.
Method: We conducted a cross-sectional, retrospective analysis of anonymised patient data, comparing the ONSD on CT imaging with the opening pressure manometry during LP on patients who presented with focal neurology or with a Glasgow coma scale score of less than 15. The study sample consisted of 67 patients, ≥18 years of age, treated at the emergency department of the Kimberly Hospital Complex from 01 March 2013 to 31 December 2014.
Results: An ONSD measurement of ≥4.8 mm identified patients with an elevated ICP with a sensitivity of 92.9% and a specificity of 97.6%, using a 95% confidence interval. Raising the ONSD cut-off value to ≥5.0 mm decreased the sensitivity to 85.7% but increased the specificity to 100%, eliminating all patients with a normal ICP.
Conclusion: The ONSD can be measured on digital images obtained by routine CT investigations of the brain to predict elevated ICP in non-trauma patients, ≥18 years of age, with acceptable sensitivity and specificity.