大部分神经管缺陷于出生前可经对孕妇人群的筛查于孕期第3~6个月内发现。
出生前三联或四联检查
三联检查包括AFP(三联检查)、hCG(人绒毛膜促性腺激素)及uE3(雌三醇)。四联检查在此基础上包括抑制素A。所有孕妇于孕15~20周内提供血清样本接受上述检查。[81]Harstall C; Institute of Health Economics (Canada). First and second trimester prenatal screening for trisomies 13, 18, and 21 and open neural tube defects. September 2012. http://www.ihe.ca/ (last accessed 11 March 2016).http://www.ihe.ca/publications/first-and-second-trimester-prenatal-screening-for-trisomies-13-18-and-21-and-open-neural-tube-defects对上述3个或4个指标的检查结果及母亲年龄、体重、种族、罹患糖尿病情况进行数学分析评价风险。三联及四联检查均可检测出75%~80%的脊柱裂妊娠接近95%的无脑畸形妊娠。[62]Norem CT, Schoen EJ, Walton DL, et al. Routine ultrasonography compared with maternal serum alpha-fetoprotein for neural tube defect screening. Obstet Gynecol. 2005;106:747-752.http://www.ncbi.nlm.nih.gov/pubmed/16199631?tool=bestpractice.com上述检查在不同国家的实施情况因国情不同而各异。
产前超声检查
尽管解读超声数据需要大量经验并可出现假阴性结果,上述三联及四联检查结果若指标升高,行常规超声检查可有效排除开放性神经管缺陷。三维超声使用多维扫描可在近80%病例中经一处椎体扫描实现准确诊断。[63]Bruner JP, Tulipan N, Dabrowiak ME, et al. Upper level of the spina bifida defect: how good are we? Ultrasound Obstet Gynecol. 2004;24:612-617.http://www.ncbi.nlm.nih.gov/pubmed/15517549?tool=bestpractice.com[64]Chen CP. Prenatal diagnosis, fetal surgery, recurrence risk and differential diagnosis of neural tube defects. Taiwan J Obstet Gynecol. 2008;47:283-290.http://www.tjog-online.com/article/S1028-4559(08)60125-4/pdfhttp://www.ncbi.nlm.nih.gov/pubmed/18935990?tool=bestpractice.com[65]Cameron M, Moran P. Prenatal screening and diagnosis of neural tube defects. Prenat Diagn. 2009;29:402-411.http://www.ncbi.nlm.nih.gov/pubmed/19301349?tool=bestpractice.com若根据家族史和/或母亲病史提示存在神经管缺陷高风险,通常要对患儿行详细的超声检查。
高分辨率超声无法可靠预测出生后脑积水、膀胱功能或运动功能层面。然而,若超声记录到其他中线结构异常表现、小脑畸形或脑畸形表现,如胼胝体发育不良,或病变节段被证实位于L3节段分水岭区域上方,则智力障碍、学习困难及严重运动损害风险显著增加。[65]Cameron M, Moran P. Prenatal screening and diagnosis of neural tube defects. Prenat Diagn. 2009;29:402-411.http://www.ncbi.nlm.nih.gov/pubmed/19301349?tool=bestpractice.com若脑室达到 15 mm 或更大,建议实行产前手术时应慎重,因为产前手术并未显示可改善该人群的结局。[82]Tulipan N, Wellons JC 3rd, Thom EA, et al; MOMS Investigators. Prenatal surgery for myelomeningocele and the need for cerebrospinal fluid shunt placement. J Neurosurg Pediatr. 2015;16:613-620.http://thejns.org/doi/full/10.3171/2015.7.PEDS15336http://www.ncbi.nlm.nih.gov/pubmed/26369371?tool=bestpractice.com