title: Optic nerve sheath diameter as a marker for evaluation and prognostication of intracranial pressure in Indian patients: An observational study.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Critical Care Medicine and Department of Radiology, Yashoda Multi-Speciality Hospital, Somajiguda, Hyderabad, Telangana, India.
authors.forename: Chetan G
authors.initials: CG
authors.lastname: Shirodkar
authors.affiliation: Department of Critical Care Medicine and Department of Radiology, Yashoda Multi-Speciality Hospital, Somajiguda, Hyderabad, Telangana, India.
authors.forename: S Manimala
authors.initials: SM
authors.lastname: Rao
authors.affiliation: Department of Critical Care Medicine and Department of Radiology, Yashoda Multi-Speciality Hospital, Somajiguda, Hyderabad, Telangana, India.
authors.forename: Dnyaneshwar P
authors.initials: DP
authors.lastname: Mutkule
authors.affiliation: Department of Critical Care Medicine and Department of Radiology, Yashoda Multi-Speciality Hospital, Somajiguda, Hyderabad, Telangana, India.
authors.forename: Yogesh R
authors.initials: YR
authors.lastname: Harde
authors.affiliation: Department of Critical Care Medicine and Department of Radiology, Yashoda Multi-Speciality Hospital, Somajiguda, Hyderabad, Telangana, India.
authors.forename: Pradeep M
authors.initials: PM
authors.lastname: Venkategowda
authors.affiliation: Department of Critical Care Medicine and Department of Radiology, Yashoda Multi-Speciality Hospital, Somajiguda, Hyderabad, Telangana, India.
authors.forename: M Uma
authors.initials: MU
authors.lastname: Mahesh
keywords: Computed tomography; intensive care unit; magnetic resonance imaging; mannitol; optic nerve sheath diameter; raised intracranial pressure; ultrasonography