Optic Nerve Sheath Diameter on Sonography in Idiopathic Intracranial Hypertension Versus Normal

Objective: To compare the mean optic nerve sheath diameter (ONSD) in patients with idiopathic intracranial hypertension (IIH) versus normal healthy individuals using B-scan ultrasonography as diagnostic tool. Study design: Cross-sectional analytical study. Place and duration of study: Armed Forces Institute of Radiology and Imaging, Rawalpindi, Pakistan, from June to December 2015. Methodology: Participants aged 30 - 50 years were divided into two groups. Group A(GP) comprised of patients who were diagnosed cases of idiopathic intracranial hypertension while normal healthy adults who volunteered to participate in the study were included in Group B (GC). Ocular B mode ultrasound scan was performed on all the participants and each eye was considered separately. The optic nerve head was visualized as a linear hypoechoic structure, and ONSD was measured 3 mm behind the retina. Atotal of three readings were taken by the same radiologist and the average of three was recorded. Mean values of both groups were compared by t-test with significance at p < 0.05. Results: Fifty-two eyes of 26 patients (26 eyes in each group) were included in the study. Twenty-four out of 26 in Group A(GP) and 23 out of 26 in Group B (GC) were females. Mean age of the patients was 33.92 +/- 4.89 years in group A(GP) while it was 34.69 +/- 4.79 years in group B (GC). Mean ONSD was 6.61 +/- 0.39 mm in group A(GP) and 4.33 +/- 0.38 mm in group B(GC) which was significantly different (p < 0.001). Conclusion: Ultrasound can provide a reliable, non-invasive tool to measure optic nerve sheath diameter in monitoring the patients with benign intracranial hypertension (BIH).