Utility of Bedside Ultrasound Measurement of Optic Nerve Sheath Diameter as a Screening Tool for raised Intracranial Pressure in Neurocritical Care Prospective Observational Study

Intracranial pressure (ICP) needs to be monitored in neurocritical patients. There is a need for portable bedside optic nerve ultrasound (ONUS) for early diagnosis to initiate the measures to reduce ICP Objective: To find the utility of bedside ONUS to diagnose raised ICP in neurocritical care. Materials and methods: After approval from the ethical committee, a prospective observational study was conducted. Optic nerve sheath diameter (ONSD) was measured in two groups: control group patients with neurological symptoms but computed tomography (CT)/magnetic resonance imaging (MRI) not suggestive of raised ICP, and second was study group patients with neurological symptoms and CT/MRI suggestive of elevated ICP Result: In patients with normal ICP, the mean ONSD in females was 4.47mm, and in males was 4.66mm. In patients with raised ICP, the mean ONSD in females was 6.45 ± 0.78 mm, and in males was 6.33 ± 0.70 mm. Regarding the correlation between Glasgow coma scale (GCS) and mean ONSD parameters, the coefficient of correlation (R) is 0.14; thus, there is a weak negative correlation. In our study, no difference was observed in raised mean ONSD in patients with different diagnoses. At a cut-off value of >4.8 mm, the sensitivity and specificity are 100% to diagnose raised ICP. Conclusion: Optic nerve sheath diameter (ONSD) is a reliable, rapid bedside screening tool in the Emergency Department/Critical Care/Operation Theatre to diagnose raised ICP. In order to keep a record of trends in ICP, we need to measure ONSD frequently. There was no correlation between GCS and ONSD measurement.