Evaluation of bedside sonographic measurement of optic nerve sheath diameter for assessment of raised intracranial pressure in adult head trauma patients

Raised intracranial pressure (ICP) is associated with poor outcome after brain injury, but is difficult to detect without invasive devices. As a part of the central nervous system, the optic nerve is surrounded by a dural sheath, and the subarachnoid space surrounding the optic nerve is subject to the same pressure changes as the intracranial compartment. Distension of the optic nerve sheath reflects an increase in cerebrospinal fluid (CSF) pressure and can be used to estimate the risk of raised ICP. Ocular sonography or brain magnetic resonance imaging (MRI) enables valid measurement of the distension of the dural sheath surrounding the optic nerve. An optic nerve sheath diameter greater than 5.8mm is likely to be associated with raised ICP. This non-invasive estimate of ICP may detect patients at risk, help make decisions regarding the placement of invasive ICP devices and allow the selection of patients for transfer to specialist centres.

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The relationship between computed tomography measurement of the optic nerve sheath diameter and elevated intracranial pressure in non-trauma patients

South African Journal of Radiology ◽

10.4102/sajr.v20i1.1060 ◽

2016 ◽

Vol 20 (1) ◽

Cited By ~ 2

Author(s):

Daniël Luyt ◽

Delmé Hurter ◽

Gina Joubert

Keyword(s):

Computed Tomography ◽

Optic Nerve ◽

Intracranial Pressure ◽

Digital Images ◽

Optic Nerve Sheath Diameter ◽

Optic Nerve Sheath ◽

Trauma Patients ◽

Cross Sectional ◽

Nerve Sheath ◽

The Brain

Background: The early detection and treatment of raised intracranial pressure (ICP) is critical in the prevention of mortality and morbidity as a result of secondary ischemic brain injury. Measuring the optic nerve sheath diameter (ONSD) on computed tomography (CT) to predict raised ICP may be useful in cases where routine CT investigations of the brain are indicated and invasive ICP monitoring is not available, or a lumbar puncture (LP) is contraindicated.Objective: The purpose of this study was to determine if the ONSD can be measured on digital images obtained by routine CT investigations of the brain, to identify patients with non-traumatic causes of elevated ICP, and to provide the observer with a non-invasive, objective measurement to predict elevated ICP.Method: We conducted a cross-sectional, retrospective analysis of anonymised patient data, comparing the ONSD on CT imaging with the opening pressure manometry during LP on patients who presented with focal neurology or with a Glasgow coma scale score of less than 15. The study sample consisted of 67 patients, ≥18 years of age, treated at the emergency department of the Kimberly Hospital Complex from 01 March 2013 to 31 December 2014.Results: An ONSD measurement of ≥4.8 mm identified patients with an elevated ICP with a sensitivity of 92.9% and a specificity of 97.6%, using a 95% confidence interval. Raising the ONSD cut-off value to ≥5.0 mm decreased the sensitivity to 85.7% but increased the specificity to 100%, eliminating all patients with a normal ICP.Conclusion: The ONSD can be measured on digital images obtained by routine CT investigations of the brain to predict elevated ICP in non-trauma patients, ≥18 years of age, with acceptable sensitivity and specificity.

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How accurate is ultrasound of the optic nerve sheath diameter performed by inexperienced operators to exclude raised intracranial pressure?

South African Journal of Radiology ◽

10.4102/sajr.v19i1.745 ◽

2015 ◽

Vol 19 (1) ◽

Cited By ~ 1

Author(s):

G. J. Du Toit ◽

D. Hurter ◽

M. Nel

Keyword(s):

Optic Nerve ◽

Intracranial Pressure ◽

Lumbar Puncture ◽

Predictive Value ◽

Optic Nerve Sheath Diameter ◽

Optic Nerve Sheath ◽

Ultrasound Measurement ◽

Raised Intracranial Pressure ◽

Cross Sectional ◽

Nerve Sheath

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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