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.