Division of Neurosurgery, University of Cape Town, Cape Town, South Africa.
Red Cross War Memorial Children's Hospital, Cape Town, South Africa.
Oper Neurosurg (Hagerstown). 2019 Jun 1;16(6):726-733. doi: 10.1093/ons/opy231.
Measurement of optic nerve sheath diameter (ONSD) is a promising technique for noninvasive assessment of intracranial pressure (ICP), but has certain limitations. A recent study showed that the deformability index (DI), a dynamic parameter quantifying the pulsatile nature of the optic nerve sheath, could differentiate between patients with high vs normal ICP.
To further evaluate the diagnostic accuracy of the DI, when interpreted together with ONSD.
This prospective study included children undergoing invasive ICP measurement as part of their clinical management. Ultrasound images of the optic nerve sheath were acquired prior to measuring ICP, the images were further processed to obtain the DI. Patients were dichotomized into high (≥20 mm Hg) or normal ICP groups and compared using the Mann-Whitney U-test. Diagnostic accuracy was described using area under the receiver operating characteristic curve (AUC), sensitivity and specificity, correlation between DI, ONSD, and ICP was investigated using linear regression.
A total of 28 patients were included (19 high ICP). The DI was lower in the high ICP group (0.105 vs 0.28, P = .001). AUC was 0.87, and a cut-off value of DI ≤ 0.185 demonstrated sensitivity of 89.5% and specificity of 88.9%. Diagnostic accuracy improved when combining DI with ONSD (AUC 0.98, sensitivity 94.7%, specificity 88.9%) and correlation with ICP improved when combined analysis of DI and ONSD was performed (Pearson correlation coefficient: 0.82 vs 0.42, respectively, P = .012).
The DI was significantly lower for patients with high vs normal ICP. This relationship improved further when the DI and ONSD were interpreted together.
视神经鞘直径（ONSD）的测量是一种有前途的无创评估颅内压（ICP）的技术，但存在一定的局限性。最近的一项研究表明，可变形指数（DI）是一种量化视神经鞘搏动性质的动态参数，可以区分高 ICP 与正常 ICP 患者。
进一步评估 DI 的诊断准确性，当与 ONSD 一起解释时。
这项前瞻性研究纳入了因临床治疗需要接受 ICP 有创测量的儿童。在测量 ICP 之前获取视神经鞘的超声图像，进一步处理图像以获得 DI。患者被分为高（≥20mmHg）或正常 ICP 组，并使用 Mann-Whitney U 检验进行比较。使用接受者操作特征曲线下面积（AUC）、敏感性和特异性来描述诊断准确性，使用线性回归研究 DI、ONSD 和 ICP 之间的相关性。
共纳入 28 例患者（19 例高 ICP）。高 ICP 组的 DI 较低（0.105 比 0.28，P=0.001）。AUC 为 0.87，DI 值≤0.185 的截断值显示敏感性为 89.5%，特异性为 88.9%。当将 DI 与 ONSD 结合时，诊断准确性提高（AUC 为 0.98，敏感性为 94.7%，特异性为 88.9%），当对 DI 和 ONSD 进行联合分析时，与 ICP 的相关性也得到改善（Pearson 相关系数：分别为 0.82 与 0.42，P=0.012）。
高 ICP 患者的 DI 明显低于正常 ICP 患者。当一起解释 DI 和 ONSD 时，这种关系进一步改善。
