Abstract
BackgroundMeasurement of optic nerve sheath diameter (ONSD) is a fast and non-invasive method in detecting elevated intracranial pressure. However, the reported normal range of ONSD was inconsistent. The objective of the study was to determine the normal range of ONSD in healthy Chinese adults.MethodsEyeball transverse diameter (ETD), optic nerve diameter (OND), and ONSD were measured by ultrasound examination in healthy adult volunteers. The OND and ONSD were assessed 3 mm behind the globe. The section showing maximal transverse diameter of the eyeball was frozen and the diameter was measured. Each ETD, OND and ONSD was examined twice and the mean value was calculated.ResultsA total of 519 healthy volunteers were included in the study. The median (interquartile range) of ETD, OND and ONSD were 22.3 (21.6 to 23.1) mm, 3.2 (2.9 to 3.4) mm, and 5.1 (4.7 to 5.4) mm, respectively. The 95 % percentile of ONSD was 5.9 mm. There was no significant difference in ETD, OND or ONSD between male and female, or between left and right eye. ONSD was significantly correlated with OND (r = 0.62, P < 0.001), and the median OND/ONSD ratio (interquartile range) was 0.63 (0.59 to 0.67).ConclusionsThe median and the 95 % percentile of sonographic measurement of ONSD are 5.1 mm and 5.9 mm in healthy Chinese adults. The ONSD is correlated with OND, while independent of gender, age, height, weight and ETD. The median OND/ONSD ratio is 0.63 and this parameter warrants further investigation in patients with brain injury.
Highlights
Measurement of optic nerve sheath diameter (ONSD) is a fast and non-invasive method in detecting elevated intracranial pressure
The ONSD is correlated with optic nerve diameter (OND), while independent of gender, age, height, weight and Eyeball transverse diameter (ETD)
There was no significant difference in ETD, OND and ONSD between the male and female, or between the left and right eye (Table 2)
Summary
Measurement of optic nerve sheath diameter (ONSD) is a fast and non-invasive method in detecting elevated intracranial pressure. The reported normal range of ONSD was inconsistent. Monitoring of intracranial pressure (ICP) is recommended in the management of intracranial hypertension [4]. Invasive intracranial devices including intra-ventricular catheters and intra-parenchymal probes are considered the gold standard for ICP measurement [5, 6]. Invasive ICP monitoring may lead to complications including hemorrhage, infection and catheter blockage or elevated ICP can be detected by computed tomography or magnetic resonance imaging, these techniques are expensive, time-consuming and requiring patient’s transportation. Measurement of optic nerve sheath diameter (ONSD) by ultrasonography has been developed and suggested as a possible indicator of intracranial hypertension [10].
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