Optic nerve sheath diameter as a marker for evaluation and prognostication of intracranial pressure in Indian patients: An observational study

Abstract

Background and Aims:The 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 Methods:We 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.Results:Group 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.Conclusion:Bedside 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.

Optic nerve sheath diameter measurement using bedside ultrasound: Is it accurate?

“…They have not commented on the presence or absence of MRI findings of raised ICP and hence have not corroborated the cut-off values of ONSD for raised ICP in Indian patients which as per Shirodkar et al . [ 14 ] was found to be somewhat less than those from previous studies.…”

“…The current authors have selected cut-off values of 4.6 mm for females, and 4.8 mm for males in accordance to a study by Shirodkar et al . [ 14 ] on 101 Indian patients who demonstrated a high level of sensitivity and specificity with these cut-off values for the diagnosis of intracranial hypertension as evident on CT or MRI imaging. However, the current authors have limited themselves to comparing the numerical accuracy of ONSD values obtained with USG and MRI.…”

Correlation of measurement of optic nerve sheath diameter using ultrasound with magnetic resonance imaging

“…[ 2 18 ] In our previous study, we performed the efficacy of ONSD measurement by USG to predict intracranial hypertension. [ 19 ] Using cut-off values of 4.6 mm for females, and 4.8 mm for males, they found a high level of sensitivity and specificity for the diagnosis of intracranial hypertension evident on computed tomography (CT) or MRI.…”

Noninvasive methods of detecting increased intracranial pressure

“…2). Shirodkar et al found ONSD cutoffs (4.6 mm for females; 4.8 mm for males) that had a sensitivity between 84.6 % (females) and 75 % (males) and a specificity of 100 % (both genders) for the detection of MRI signs of elevated ICP, such as midline shift, edema, and effacement [33]. Similarly, a study of 24 adult patients compared ONSD by ocular ultrasound to CT findings of midline shift, sulcal effacement with significant edema, third ventricle collapse, and hydrocephalus, and using a cutoff of 5.0 mm, they achieved a sensitivity of 100 %, specificity of 75 %, PPVof 95.4 %, and NPVof 100 % [34].…”