A 2-year-old male patient with abasia and deformities of lower extremities. He was the second child of a diabetic mother whose obstetric history showed absence of any formal prenatal examinations. Family history did not indicate any congenital disorders. Clinical examination revealed hypoplastic lower limbs with muscular paralysis and atrophy.
A full spine MRI was performed on a 1.5 Tesla MRI scanner, consisting of T1 and T2 sequences in sagittal and axial plane. Paramagnetic contrast agent was administered intravenously. The MRI showed minor abnormalities of the spinal architecture with biconvex formation of the vertebral bodies C4 to C6 (Fig. 1) and L4 to L5. In addition, there was marked hypoplasia of the sacral vertebrae and agenesis of the coccyx (Fig. 2). The spinal cord was shorter than normal and terminated at the level of the T12. Moreover, the medullary cone was thickened and wedge-shaped (Fig. 3). Syringomyelia was recognised at the T4-T11 level and hydromyelia from the medullary cone up to the filum terminale. The cauda equina was thickened and fixed (Figs 3,4).
Caudal regression syndrome pathogenesis is thought to derive from a combination of underlying genetic predisposition and environmental factors. Genetic defects are thought to contribute in the pathogenesis of CRS, include mutations of CYP26A1, HOXD13 & HLXB9 genes [1]. Maternal diabetes mellitus is a well-established environmental risk factor and insulin-dependent diabetic women with poor glycemic control are 300 times more predisposed to have a child with CRS [2,3].
In our case, there was a positive history of uncontrolled maternal diabetes mellitus, indicating its contribution to CRS pathogenesis. However, genetic testing was not performed due to patient’s rejection. The clinical presentation of CRS mainly depends on the level and the extent of the spinal cord dysplasia.
Renshaw [4], introduced the classification of the syndrome into five types, based on the extent of the skeletal anomalies:
Type I: Total or partial unilateral sacral agenesis.
Type II: Partial sacral agenesis with a bilaterally symmetrical defect and a stable articulation between the ilia and the first sacral vertebra, which can be normal or hypoplastic.
Type III: Variable lumbar and total sacral agenesis with the ilia articulating with the sides of the lowest vertebra present.
Type IV: Variable lumbar and total sacral agenesis, with the caudal endplate of the lowest vertebra resting above either fused ilia or an iliac amphiarthrosis.
Type V: Syringomyelia.
Severe cases of CRS can be diagnosed by observing the shorter than normal crown-rump length in antenatal sonography during the first trimester. MRI is the gold standard imaging technique for diagnosis of CRS and its deformities. According to imaging findings CRS patients are categorised into two groups:
Group 1: patients with a blunt conus medullaris which terminates above the normal level (L1); sacral deformities are more extensive in this group.
Group 2: patients with an elongated conus medullaris which terminated below the normal level, linked to a thickened filum terminale or intraspinal lipoma; the neurologic symptoms are more serious [5].
Treatment of patients with CRS is individualised, depending on the degree of the lower limb deformities and the presence of motor paralysis. When hydrocephalus and Chiari malformations are absent, attempts can be made to reconstruct the lower extremities to improve ambulation. Other syndromes and abnormalities associated with CRS are the VACTERL syndrome [6,7], as well as Currarino syndrome [8].
Learning Points:
- CRS is rare congenital abnormality arising from an insult before the fourth week of gestation and exhibits an extended range of malformation.
- MRI investigation is the gold standard the evaluation of CRS and its deformities.
- Treatment is decided per the clinical symptoms and the degree of the combine defects.
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Caudal regression syndrome (CRS)
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Based on the provided spinal MRI images, the following main features can be observed:
Considering the child’s lower limb deformities, difficulty walking (abasia), and maternal history of diabetes during pregnancy, the following diagnoses merit consideration:
Taking into account the child’s age, symptoms (lower limb deformities and difficulty walking), maternal diabetes history, and MRI findings showing sacral vertebral absence and a high conus medullaris termination, the most fitting diagnosis is Caudal Regression Syndrome (CRS).
For further clarification of the filum terminale (e.g., thickening, fatty deposition), higher-resolution MRI or genetic testing can be conducted if feasible to evaluate any concurrent neural tube anomalies.
Based on the child’s current lower limb deformities and motor function deficits, the following comprehensive treatment and rehabilitation principles can be considered:
Throughout the rehabilitation process, closely monitor bone health, joint range of motion, and cardiopulmonary endurance. Regular bone density assessments can be performed if necessary to evaluate skeletal maturity and associated risks.
Disclaimer: The above analysis is based solely on the current imaging and medical history, offering clinical suggestions for reference. A final treatment plan must be determined by a multidisciplinary team (including orthopedics, neurosurgery, and rehabilitation) according to the child’s actual condition. This report cannot replace in-person consultation or professional medical advice.
Caudal regression syndrome (CRS)
