(P2-73) Ocular Nerve Sheath Diameter for Evaluation of Raised Intracranial Pressure in Patients Presenting to the Emergency Department - A Prospective, Observational Study

BackgroundUltrasonography of optic nerve sheath diameter (ONSD) may be useful in detecting raised intracranial pressure (ICP) in head injury (HI). There is limited data from India.ObjectiveThe objective of this study was to evaluate the utility of measuring ONSD for diagnosis of raised intracranial pressure in HI victims in the emergency department.MethodsFifty-two HI patients presenting between February to August 2009 were included, A CT head scan was performed and simultaneous ocular ultrasound was done by an emergency physician who had underwent goal-directed training in ophthalmic sonography by a linear probe of 10 MHz. An ONSD greater than > 5 mm for patients > 15 years of age, 4.5 mm for 1–15 years of age, and 4 mm for infants were considered abnormal. The two modalities of diagnosis were compared.ResultsThe median age was 30 years (Range = 0.25–72 years). A total of 90.4% were male and 9.6% were female. A total of 71.2% had severe HI, 19.2% had moderate HI, and 9.6% had mild HI. A raised ICP based on CT findings was present in 42 (80.8%) patients. Mean optic nerve diameter in patients with raised ICP was 5.11 + 1.56 mm compared to 5.04 + 1.6 mm in patients with no features of raised ICP. Sensitivity and specificity of ONSD as a screening test for detection of raised intracranial pressure were 57.1% and 40%, respectively with a positive predictive value and negative predictive value of 80% and 18.1%, respectively.ConclusionsThe evaluation of the ONSD diameter is a simple and non-invasive potential tool in initial assessment of raised intracranial pressure.