Abstract

DU TOIT, G.J.; HURTER, D.  and  NEL, M.. How accurate is ultrasound of the optic nerve sheath diameter performed by inexperienced operators to exclude raised intracranial pressure?. S. Afr. J. radiol. (Online) [online]. 2015, vol.19, n.1, pp.1-5. ISSN 2078-6778.  http://dx.doi.org/10.4102/SAJR.v19i1.745.

BACKGROUND: It has been well documented that ultrasound measurement of the optic nerve sheath diameter performed by an experienced operator shows good correlation with raised intracranial pressure, irrespective of the cause OBJECTIVE: To establish the accuracy of this technique performed by inexperienced operators METHOD: A prospective analytical cross-sectional study was conducted. All patients ≥18 years of age who presented at our medical casualty and emergency departments with suspected meningitis were enrolled in the study. All patients were evaluated with the use of optic nerve sheath diameter ultrasound with or without computed tomography brain scan prior to lumbar puncture. Lumbar puncture opening pressure measurements were compared with the ultrasound measurements RESULTS: A total of 73 patients were enrolled in the study, of whom 14 had raised intracranial pressure. The study had a sensitivity of 50% (95% confidence interval (CI) 26.8%-73.2%) and specificity of 89.8% (95% CI 79.5%-95.3%) with a positive predictive value of 54.8% (95% CI 29.1%-76.8%) and negative predictive value of 88.3% (95% CI 77.8%-94.2%). The likelihood ratio of a positive test was 4.92 (95% CI 1.95-11.89) and that of a negative test 0.56 (95% CI 0.29-0.83). Cohen's kappa value was 0.41 which indicates a moderate agreement. The receiver operating characteristic (ROC) curve had an area under the curve (AUC) of 0.73 (95% CI 0.51-0.95 CONCLUSION: Ultrasound measurement of the optic nerve sheath diameter can be used to exclude raised intracranial pressure, even in the hands of inexperienced operators.

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