Allan, John Samuel (2016) Diagnostic Utility and Accuracy of Optic Nerve Sheath Diameter (ONSD) in detecting raised Intracranial Tension. Masters thesis, Christian Medical College, Vellore.
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Abstract
OBJECTIVES: 1. To assess the diagnostic utility and accuracy of ONSD in detecting raised ICT in patients with CNS infection and CVA. 2. To assess the temporal profile of ONSD in these patients. METHODS: After obtaining informed consent the ONSD was measured using ultrasound in supine mode 3mm posterior to the papilla over the closed eyelid. The patients were followed up on day 4 of hospitalization. The CSF pressure measurement was done independently by the treating team doctors during LP. For those who undergo imaging of the brain, the images were read by the radiologist independent of clinical data. Accuracy of ONSD with the brain imaging and CSF pressure were assessed by plotting ROC curve. The sensitivity and specificity were calculated with 95% confidence interval. Chi-square test was used to assess the association with ICT. RESULTS: 1. At the cutoff value of 0.54mm we obtained 52.38% sensitivity and 76.67% specificity. The positive predictive value was 61.1% (95% CI 35.7-82.7) and the negative predictive value was 51.3% (95% CI 51.3-84.4) 2. Diagnosis and management decisions based on the following range of ONSD values: a. For the ONSD values from 0.7-0.58:- Patients will require immediate anti edema measures and neuroimaging. b. For the ONSD values from 0.43-0.39:-Neuroimaging not required. c. For the ONSD values from 0.43 – 0.58:- The need for imaging to be decided based on clinical evaluation. CONCLUSION: The study shows that ONSD measured using ultrasound is a rapid and convenient bedside test for assessing for raised intracranial tension in patients with meningitis. It can be used as a useful adjunct to the clinical examination in suspected meningitis to measure ICT. A normal ONSD conclusively rules out raised ICT. An elevated value confirms the presence of raised ICT and can be used to initiate treatment for raised ICT. In both these situations it is useful in decision making on the need for imaging in meningitis and initiating anti-edema measures. However at intermediate ONSD value the need for imaging has to be decided based on clinical considerations. ONSD can also have a role as a convenient bedside test in follow up monitoring of ICT in patients with meningitis. ONSD measurement may not be as useful in assessing raised ICT in patients with cerebrovascular accident.
| Item Type: | Thesis (Masters) |
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| Additional Information: | Reg.No.201311453 |
| Uncontrolled Keywords: | Diagnostic Utility ; Accuracy ; Optic Nerve Sheath Diameter (ONSD) ; Intracranial Tension. |
| Subjects: | MEDICAL > General Medicine |
| Depositing User: | Subramani R |
| Date Deposited: | 06 Feb 2019 00:14 |
| Last Modified: | 06 Feb 2019 00:14 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/10485 |
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