CASE 14807 Published on 28.06.2017

Caudal regression syndrome

Section

Paediatric radiology

Case Type

Clinical Cases

Authors

Julian A. Santos1, Antonio Marlo P. Nievera, MD2

(1) Straight Intern in Radiology (Primary Author)
(2) Associate Professor of Radiology (Co-Author)
Philippine General Hospital,
University of the Philippines;
Taft Avenue, 1000 Manila, Philippines;
Email:julian.alejandro.santos@gmail.com
Patient

4 months, male

Categories
Area of Interest Paediatric ; Imaging Technique CT
Clinical History
Four-month-old male patient presenting with small lower limbs and pelvis, flexion contracture in both knees with webbing of the popliteal fossae, bilateral talipes equinovarus, and non-palpable lower back vertebrae. Born post-term to a 39 year-old primigravid diabetic mother. No significant symptoms during the immediate postnatal period. No cognitive delays.
Imaging Findings
No antenatal images available.

Postnatal imaging shows:

Plain radiographs revealed unremarkable cardiopulmonary and visceral findings. There is hemivertebra of T12 with progressive caudal tapering of the formed vertebral bodies, agenesis of the lumbosacrococcygeal vertebrae, hypoplastic pelvic bones, and shallow articulation of the femora within the acetabula.

Plain CT of the lumbosacral spine demonstrated that the last normal-appearing vertebra with rib articulation is T11. T12 vertebra is hypoplastic and manifests a bifid spinous process. The cauda equina and spinal canal terminate at T12. A small osseous density is seen caudal to T12, likely representing a rudimentary L1. Posteroinferior to this osseous density, the last pair of ribs articulate with each other along the midline. There are no identifiable vertebrae, sacrum, and coccyx inferior to the aforementioned level. The iliac crests are hypoplastic and apposed medially. The acetabula are shallow. The femoral heads are flattened and displaced outwardly from the hip joints.
Discussion
Caudal regression syndrome (CRS) is a spectrum of caudal anomalies in multiple systems (i.e. anorectal atresia, renal agenesis, epi-/hypospadias, neurogenic bladder, lower limb hypoplasia, etc.). Lumbosacral hypogenesis is the hallmark of CRS [1, 2]. The incidence of CRS is 0.25 to 1 in every 10, 000 normal pregnancies, with a 200 to 250- fold increased likelihood in diabetic mothers [2]. CRS arises from faulty embryogenesis of the caudal mesoderm (precursor of the lower spine and urogenital/anorectal structures) prior to 7 weeks age of gestation. Genetic and/or environmental insults inhibit the migration of neurons, paraxial mesodermal cells (somites), and lateral plate mesodermal cells (lower alimentary tract) through the primitive streak into the caudal regions, which results in the constellation of musculoskeletal, neural, urogenital, and visceral findings we see in CRS [1].

Presenting signs and symptoms vary greatly in terms of severity – they may range from asymptomatic isolated malformations of the lower spine and limb or mild motor weakness to more pronounced motor paralysis, complete sensory loss, and atrophy of the lower extremities [1].

Imaging is essential to characterise the abnormalities, as prognosis depends on their severity. MRI and prenatal ultrasound are the cornerstones of imaging [1, 2]. The lower limbs may show varying degrees of abnormalities, such as rudimentary, shield-like fused pelvic bones, contractures, symelia/amelia, syndactly, equinovarus, etc [1, 2]. MRI is useful for determining the degree of vertebral anomalies, i.e. narrowing of the spinal canal and cord tethering [3]. Axial images are useful in looking for thickened filum, hydromyelia, myelomeningocele, lipoma, as well as in characterising anomalies in other organ systems [1]. Prenatal diagnosis of caudal regression is done mainly through modalities without ionising radiation, i.e. MRI and ultrasound. Obstetric sonography is the prenatal screening modality of choice. Early ultrasound findings, especially in the first trimester, may be limited to short crown-to-rump length and abnormalities in the yolk sac [2]. Sonographic findings later in pregnancy may show spinal shortening, agenesis of the lumbar and/or sacrococcygeal vertebrae, short femora with flattening of the femoral head, hip bone hypogenesis, contractures and immobility of the lower limbs [2].

It is paramount that radiologists and obstetric sonologists are acquainted with the anomalies seen in CRS because they are often the first to detect its presence, usually through prenatal ultrasound. Since the pathology is irreversible, treatment is supportive and is aimed towards achieving a state of independence and normality for the patient.
Differential Diagnosis List
Caudal regression syndrome
VACTERL sequence
Currarino syndrome
Final Diagnosis
Caudal regression syndrome
Case information
URL: https://eurorad.org/case/14807
DOI: 10.1594/EURORAD/CASE.14807
ISSN: 1563-4086
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