• Chetan G Shirodkar, S Manimala Rao, Dnyaneshwar P Mutkule, Yogesh R Harde, Pradeep M Venkategowda, and M Uma Mahesh.
• Department of Critical Care Medicine and Department of Radiology, Yashoda Multi-Speciality Hospital, Somajiguda, Hyderabad, Telangana, India.
• Indian J Crit Care Med. 2014 Nov 1;18(11):728-34.

Background And AimsThe aim was to evaluate efficacy of optic nerve sheath diameter (ONSD) by ultrasound as a noninvasive method for detecting raised intracranial pressure (ICP) in intensive care unit, to compare with computed tomography/magnetic resonance imaging (MRI) findings of raised ICP and to prognosticate ONSD value with treatment.Materials And MethodsWe conducted a prospective, observational study on 101 adults by including 41 healthy individuals in group A as control and 60 patients in group B admitted with fever, headache, vomiting, and altered sensorium. We examined them in supine position using 10 MHz linear array probe on closed eyelid. ONSD was measured 3 mm behind the globe in each eye. A mean binocular ONSD > 4.6 mm in female and 4.8 mm in male was considered abnormal. Midline shift, edema, effacement or ONSD > 5.0 mm on T2 MRI suggestive of elevated ICP was used to evaluate ONSD accuracy.ResultsGroup A mean ONSD was 4.6 mm in females and 4.8 mm in males. Group B mean ONSD for 17 females was 5.103 ± 0.6221 mm (P = 0.002) and for 43 males 5.081 ± 0.5799 mm (P = 0.032). Radiological sign of raised ICP was confirmed in 35 patients (females = 11 and males = 24) with high ONSD value. Sensitivity of detecting raised ICP by ONSD was 84.6% in females and 75% in males while specificity was 100% in both genders. Out of 25 patients without radiological signs of raised ICP 10 patients showed high ONSD (females = 4.735 mm and males = 4.907 mm). ONSD was well prognosticated with treatment modalities.ConclusionBedside ocular ultrasonography for measuring ONSD can be used an early test for diagnosing raised ICP as it is a noninvasive, cost effective bedside test, which can be repeated for re-evaluation.

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