Bedside sonographic measurement of optic nerve sheath diameter as a predictor of intracranial pressure in ED.

BACKGROUND: Ocular ultrasonography of optic nerve sheath diameter (ONSD) to determine intracranial pressure (ICP) has become favorable in recent years.

OBJECTIVE: To demonstrate the efficacy of ONSD measurement in determining the ICP increase due to nontraumatic events in the emergency department.

METHODS: A total of 100 patients with suspected nontraumatic intracranial event were enrolled in this prospective study. Patients were divided equally into 2 groups including 50 patients as group I with pathology on cranial computed tomography (CT) and group II with normal cranial CT. Prior to CT scans, patients underwent ONSD measurement by a radiologist using 11- and 14-MHz transducers.

RESULTS: The ONSD values of groups I and II were 5.4±1.1and 4.1±0.5mm, respectively. Optic nerve sheath diameter was found to be larger on the side of lesion in patients with a lesion (P<.05). The cutoff value of the difference between ONSD values of both eyes in the presence of pathology was determined as 0.45 (sensitivity, 80%; specificity, 60%; the area under the curve, 0.794; 95% confidence interval, 0.705-0.883). The between-ONSD and midline shift size was statistically significant (r=0.366, P=.009). The cutoff value of ONSD for the detection of midline shift was determined as 5.3mm (sensitivity, 70%; specificity, 74%; the area under the curve, 0.728; 95% confidence interval, 0.585-0.871).

CONCLUSION: Optic nerve sheath diameter measurement via bedside ocular ultrasonography in patients with suspected intracranial event in the emergency department is a useful method to determine ICP increase and its severity.