Blehar David J, Gaspari Romolo J, Montoya Anthony, Calderon Richard
Department of Emergency Medicine, University of Massachusetts Medical School, 55 Lake Ave N, Worcester, MA 01655, USA.
J Ultrasound Med. 2008 Mar;27(3):407-11. doi: 10.7863/jum.2008.27.3.407.
There are several approaches to sonographic imaging and measurement of the optic nerve sheath diameter (ONSD). In this study, we sought to compare visual axis measurements of the optic nerve sheath (ONS) with traditional coronal axis measurements to assess for correlation.
The ONS was visualized in 2 views on both eyes of healthy volunteers using an 8.5-MHz probe. Coronal axis views were obtained with the probe placed at the lateral canthus directed nasally posterior to the globe. Subsequent imaging was made along the midline visual axis. The diameter in this view was measured at several points posterior to the sclera (2, 3, 6, 9, 12, and 15 mm).
Twenty-seven subjects were enrolled (54 scans). There was a significant difference between ONSDs measured in each axis, with a coronal axis mean diameter of 3.4 mm and visual axis mean diameters at 2, 3, 6, 9, 12, and 15 mm of 4.28, 4.32, 5.15, 5.74, 6.39, and 7.42 mm, respectively (P < .05). The Pearson coefficient showed no correlation between coronal axis and visual axis measurements, with R values ranging from 0.51 to 0.69. There was a statistically significant increase in the ONSD as the nerve coursed posteriorly when measured in the visual axis.
Visual axis measurements do not reliably correlate with coronal axis measurements. The consistently larger diameter measured in the visual axis as well as the gradually increasing diameter posteriorly suggests measurement of an artifactual shadow rather than the true ONS.
超声成像和测量视神经鞘直径（ONSD）有多种方法。在本研究中，我们试图比较视神经鞘（ONS）的视轴测量值与传统冠状轴测量值，以评估两者之间的相关性。
使用8.5MHz探头在健康志愿者双眼的两个视图中观察ONS。将探头置于外眦，向眼球鼻侧后方放置以获得冠状轴视图。随后沿中线视轴进行成像。在巩膜后方的几个点（2、3、6、9、12和15mm）测量该视图中的直径。
共纳入27名受试者（54次扫描）。各轴测量的ONSD之间存在显著差异，冠状轴平均直径为3.4mm，视轴在2、3、6、9、12和15mm处的平均直径分别为4.28、4.32、5.15、5.74、6.39和7.42mm（P <.05）。皮尔逊系数显示冠状轴和视轴测量之间无相关性，R值范围为0.51至0.69。在视轴测量时，随着神经向后走行，ONSD有统计学意义的增加。
视轴测量与冠状轴测量无可靠相关性。视轴测量中始终较大的直径以及向后逐渐增加的直径表明测量的是伪像阴影而非真正的ONS。
