Prenatal diagnosis of segmental spinal dysgenesis

Abstract

CASE REPORTA 20-year-old woman (gravida 1, para 0) was referred at22 weeks and 3 days of gestation with bilateral talipesand a suspected spinal abnormality. The nuchal translu-cency assessed at 12 weeks and 3 days was 2.3 mmwith a CRL (crown–rump length) of 59.8 mm givingan adjusted risk for Down syndrome of 1:825. Thepatient had an uneventful medical history, and no his-tory of abdominal trauma was elicited. We performeda detailed 2D–3D ultrasound examination of the fetalanatomy. This confirmed the finding of bilateral talipes,and reduced movements across the knee joint on bothsides were observed. In addition, complete disjunction ofthe thoracic and lumbar spine at the L1 and L2 level wasseen (Figure 1(a)). There was no spina bifida or hemiver-tebra nor any evidence of Arnold Chiari malformationor further associated structural abnormalities.In view of the findings suggestive of neurologicaldamage below the level of the spinal lesion, the par-ents opted for a termination of pregnancy. Cytogeneticanalysis of cells obtained from the fetal blood at thetime of the fetocide showed normal 46,XX karyotype.Postmortem fetal X-ray and (magnetic resonance imag-ing (MRI) scan were performed prior to pathologicalexamination, in order to better define the spinal abnor-mality and to inform of the risk of recurrence of theabnormality in future pregnancies. X-ray showed a com-plete disjunction of thoracic and lumbar spines withsevere kyphosis and gibbus apex marking the level ofthe lesion (Figure 1(b)). The L1 and L2 spinous processwere hypoplastic and a vestigial L1 body was fused toT12, while the L2 body was agenetic. The lower threelumbar and the sacrococcygeal vertebrae were present.Postmortem MRI confirmed the configuration of thespine as shown on the plain films (Figure 1(c)). Fur-thermore, it showed overlap of the unossified spinalsegments and an abnormally thin spinal cord at the levelof the lesion, while there was evidence of a thickened