PRENATAL DIAGNOSIS
Prenat Diagn 2007; 27: 979–981. Published online 4 July 2007 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/pd.1807
RESEARCH LETTER
Prenatal diagnosis of segmental spinal dysgenesis N. Fratelli1 , P. Rich2 , I. Jeffrey3 , A. Bahmaie4 , B. Thilaganathan1 and A. T. Papageorghiou1 * 1
Fetal Medicine Unit, St George’s Hospital NHS Trust, Department of Obstetrics and Gynaecology, Blackshaw Road, London SW17 0QT, UK 2 Neuroradiology, St George’s Hospital NHS Trust, Department of Obstetrics and Gynaecology, Blackshaw Road, London SW17 0QT, UK 3 Perinatal Pathology, St George’s Hospital NHS Trust, Department of Obstetrics and Gynaecology, Blackshaw Road, London SW17 0QT, UK 4 Department of Obstetrics and Gynecology, St Peter’s Hospital, Guildford Road, Chertsey, Surrey, KT16 0PZ, UK
CASE REPORT 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 *Correspondence to: A. T. Papageorghiou, Fetal Medicine Unit, 4th Floor, Lanesborough Wing, St George’s Hospital NHS Trust, Blackshaw Road, London SW17 0QT, UK. E-mail:
[email protected]
Copyright 2007 John Wiley & Sons, Ltd.
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 in postnatally diagnosed SSD in 2 case series of 7 and 10 cases, respectively (Fondelli et al., 1996). These are a normal upper spinal cord, an abnormal cord segment devoid of nerve roots and a bulky, thickened, and low-lying lower cord caudally. The presence of a cord segment within the caudal spinal canal is a dominant and unique feature of SSD. However, when the lumbosacral spine is involved, the level of the segmental anomaly is too caudal for a spinal cord segment to develop below (Fondelli et al., 1996). Postnatally SSD is often associated with closed spinal dysraphisms which may also involve the spinal cord above, at, or below the level of the segmental anomaly (Tortori-Donati et al., 1999). Clinically, SSD is characterized by moderate to severe motor impairment and affected newborns can be paraplegic at presentation. The degree of neurological deficit depends not only on the caliber of the spinal cord at the level of the dysgenesis, but also on how well the residual spinal cord functions. As a consequence, there appears to be a continuum ranging from moderate hypoplasia to absence of the spinal cord, with the clinical picture depending on the degree of residual function of the malformed spinal cord. It is Received: 18 May 2007 Accepted: 29 May 2007 Published online: 4 July 2007
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Figure 1—(a) Prenatal ultrasound showing a sagittal section of the fetal spine. (b) Postmortem X-ray clearly showing the spinal abnormality. (c) Postmortem MRI showing overlap of the unossified spinal segments and an abnormally thin spinal cord at the level of the lesion, with evidence of a thickened lower cord caudally. The arrows point out the area of overlap of the spinal segments
important to note that if newborns with SSD are not necessarily paraplegic at presentation, they are at increased risk for the development of neurological deficit due to both the inherent instability and congenital stenosis of the spine (Faciszewski et al., 1995). In the case we presented, there was evidence of bilateral talipes and reduced movement across the knee joints. Associated deformities of the lower limbs are usually associated with SSD, and are mainly represented by flexion-abduction of the hip joints, flexion of the knees, and equinovarus feet, which in the most severe forms result in a sitting position described as ‘Buddhalike’ (Redhead et al., 1968). As these deformities depend on the level of paraplegia as well as on the presence of abnormal muscle attachment due to the spinal deformity, they often require multistep surgical correction. Other associations include renal abnormalities and neurogenic bladder (Tortori-Donati et al., 1999). An association between SSD and caudal spinal anomalies such as coccygeal or sacrococcygeal agenesis has been reported (Tortori-Donati et al., 1999). SSD and caudal regression syndrome (CRS) can be considered part of a single spectrum of segmental malformation of the spine and spinal cord. From an embryological point of view they differ in the segmental location of the derangement along the longitudinal axis of the embryo. When such derangement involves an intermediate segment along the longitudinal embryonic axis, SSD results; if it involves the most caudal segment, CRS results (Tortori-Donati et al., 1999). The differential diagnosis of this malformation also includes hemivertebra and Jarcho–Levin syndrome. Hemivertebra is a rare congenital spinal anomaly where only one side of the vertebral body develops, resulting in deformation of the spine, such as scoliosis, lordosis, or kyphosis. It is associated with a favorable outcome when isolated, but it can also be part of syndromes like VACTERL or COVESDEM association. VACTERL association is characterized by vertebral anomalies, such as anal atresia, tracheoesophageal fistula, cardiac anomalies, and radial limb dysplasia. A single umbilical artery can also be observed. A diagnosis of this condition requires the presence of at least three of the seven cardinal anomalies Copyright 2007 John Wiley & Sons, Ltd.
of the association (Miller and Kolon, 2001). COVESDEM association includes mesomelic dysplasia (particularly of the upper extremities), costovertebral segmentation defects (hemivertebrae, vertebral fusion, and butterfly vertebrae), and facial abnormalities (hypertelorism, depressed nasal bridge, large bony upper lip, constantly open mouth, and peg teeth) (Wadia et al., 1978). Jarcho–Levin syndrome is a lethal condition inherited with an autosomic recessive pattern. The disorder is characterized by short thorax with a ‘crablike’ rib cage and multiple vertebral and rib defects (Romero et al., 1988). The case shows that prenatal diagnosis of segmental spinal dysgenesis is achievable using ultrasound. Ultrasound features in this case consisted of the following: malalignment of the caudal segment of the spine in the sagittal plane, and a smaller degree of malalignment in the coronal plane; talipes equinovarus; and reduced movements of the knee joint. Importantly there were no cerebral features, as would be the case in open spina bifida (Nicolaides et al., 1986). However, it is likely that ultrasound features will depend on the severity of the malformation and on its segmental level along the longitudinal embryonic axis. As the spinal cord cannot readily be seen using ultrasound, prenatal fetal MRI may be needed to visualize the typical features of the presence of the spinal cord below the lesion. REFERENCES Faciszewski T, Winter RB, Lonstein JE, Sane S, Erickson D. 1995. Segmental spinal dysgenesis: a disorder different from spinal agenesis. J Bone Joint Surg Am 77: 530–537. Fondelli MP, Cama A, Rossi A, Piatelli GL, Tortori-Donati P. 1996. Segmental spinal dysgenesis: MRI findings in 7 cases (abstr). Neuroradiology 38(Suppl. 2): 89. Miller OF, Kolon TF. 2001. Prenatal diagnosis of VACTERL association. J Urol 166(6): 2389–2391. Nicolaides KH, Campbell S, Gabbe SG, Guidetti R. 1986. Ultrasound screening for spina bifida: cranial and cerebellar signs. Lancet 2(8498): 72–74. Redhead RG, Vitali M, Trapnell DH. 1968. Congenital absence of the lumbar spine. Br Med J 3: 595–596. Romero R, Ghidini A, Eswara MS, Seashore MR, Hobbins JC. 1988. Prenatal findings in a case of spondylocostal dysplasia type I (Jarcho-Levin syndrome). Obstet Gynecol 71(6): (Pt 2): 988–991. Prenat Diagn 2007; 27: 979–981. DOI: 10.1002/pd
SEGMENTAL SPINAL DYSGENESIS Scott RM, Wolpert SM, Bartoshesky LF, Zimbler S, Karlin L. 1988. Segmental spinal dysgenesis. Neurosurgery 22: 739–744. Tortori-Donati P, Fondelli MP, Rossi A, Raybaud CA, Cama A, Capra V. 1999. Segmental spinal dysgenesis: neuroradiologic findings with clinical and embryologic correlation. AJNR Am J Neuroradiol 20(3): 445–456.
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Wadia RS, Shirole DB, Dikshit MS. 1978. Recessively inherited costovertebral segmentation defect with mesomelia and peculiar facies (COVESDEM syndrome). A new genetic entity? J Med Genet 15: 123–127.
Prenat Diagn 2007; 27: 979–981. DOI: 10.1002/pd
