Prenatal diagnosis of segmental spinal dysgenesis

Abstract

A 20-year-old woman (gravida 1, para 0) was referred at 22 weeks and 3 days of gestation with bilateral talipes and a suspected spinal abnormality. The nuchal translucency assessed at 12 weeks and 3 days was 2.3 mm with a CRL (crown-rump length) of 59.8 mm giving an adjusted risk for Down syndrome of 1 : 825. The patient had an uneventful medical history, and no history of abdominal trauma was elicited. We performed a detailed 2D-3D ultrasound examination of the fetal anatomy. This confirmed the finding of bilateral talipes, and reduced movements across the knee joint on both sides were observed. In addition, complete disjunction of the thoracic and lumbar spine at the L1 and L2 level was seen (Figure 1(a)). There was no spina bifida or hemivertebra nor any evidence of Arnold Chiari malformation or further associated structural abnormalities.In view of the findings suggestive of neurological damage below the level of the spinal lesion, the parents opted for a termination of pregnancy. Cytogenetic analysis of cells obtained from the fetal blood at the time of the fetocide showed normal 46,XX karyotype. Postmortem fetal X-ray and (magnetic resonance imaging (MRI) scan were performed prior to pathological examination, in order to better define the spinal abnormality and to inform of the risk of recurrence of the abnormality in future pregnancies. X-ray showed a complete disjunction of thoracic and lumbar spines with severe kyphosis and gibbus apex marking the level of the lesion (Figure 1(b)). The L1 and L2 spinous process were hypoplastic and a vestigial L1 body was fused to T12, while the L2 body was agenetic. The lower three lumbar and the sacrococcygeal vertebrae were present. Postmortem MRI confirmed the configuration of the spine as shown on the plain films (Figure 1(c)). Furthermore, it showed overlap of the unossified spinal segments and an abnormally thin spinal cord at the level of the lesion, while there was evidence of a thickened lower cord caudally, features typical of segmental spinal dysgenesis (SSD) (Tortori-Donati et al., 1999). Postmortem pathological examination of the fetus showed bilateral talipes deformities in the lower limbs and segmental spinal dysgenesis affecting the upper lumbar spine. There was replacement of the L1 and L2 vertebral bodies with irregular masses of largely unossified cartilage, and abnormal angulation of the spine in the affected area was seen.We report here the first case of prenatally diagnosed SSD. This is a rare condition characterized by localized deformity of the thoracolumbar, lumbar, or lumbosacral spine associated with abnormal development of the underlying spinal cord and nerve roots (Scott et al., 1988).Postnatally, the diagnostic gold standard is MRI as it allows evaluation of both the vertebral abnormality and the spinal cord lesion. The neuroradiologic picture is variable according to the extent and level of the abnormality, the degree of resulting kyphosis, and the presence of associated abnormalities. The typical neuroradiologic picture has been described...

Segmental Spinal Cord Hypoplasia in a Holstein Friesian Calf

“…In humans, diagnosis of SSD is performed in utero using ultrasound, but prenatal fetal MRI would be useful to identify spinal cord conditions and typical features of each disease (Fratelli et al., ). This is the first case of intravitam diagnose of segmental hypoplasia in a calf using myelography and MRI.…”

Segmental Spinal Dysgenesis

“…Prenatal imaging cases of SSD are scarce, with published cases primarily involving ultrasound 7 - 9 and MRI. 5 , 10 Similar to previously published examples of SSD, the lower extremity abnormalities in our case were also the first findings identified via routine ultrasound screening.…”