From Spine to Limbs: Imaging Insights and Clinical Correlation in Caudal Regression Syndrome

Caudal regression syndrome (CRS) refers to a spectrum of congenital structural defects of the caudal region. We present a case of caudal regression syndrome with the objective of correlating the symptoms of caudal regression syndrome with the detailed imaging findings. A 05-year-old boy who was admitted to Mymensingh Medical College Hospital in August 2025 , presented with a post-urethroplasty state of hypospadias, complaining of urinary incontinence through the normal meatus and a urethrocutaneous fistula. He had dribbling of urine through hypospadias and deformed feet since birth. He also developed progressive lower limb weakness and walking difficulty at the age of 3 years. On clinical examination bilateral calf and hypothenar muscle wasting, reduced muscle power and tone, absent ankle and diminished knee jerks, diminished bulbocavernosus reflex, intact perianal sensation and anal tone were observed. Right-sided planovalgus (flat foot), left-sided cavus foot deformity, a smaller pelvic girdle with flat buttocks and hard swelling over the lower lumbar region were found. On x-ray lumbosacral spine both view, low-positioned L5 vertebra fused with a rudimentary S1 vertebra on the right with the absence of the rest of the sacral pieces and coccyx, broad spinous process of L5 were seen. Vertical talus, absent navicular bones and adducted forefeet and supinated great toes were seen on x-ray foot both view. RGU and MCU confirmed urethrocutaneous fistula. MRI of whole spine with contrast showed spinal cord and subarachnoid space termination at a slightly upper level with multifocal syrinx and anterior epidural lipoma. MR myelogram revealed short and thickened filum terminale. MR neurography demonstrated altered course of both sided lumbo-sacral plexus. Multifocal syrinx at cervical and dorso-lumbar vertebral levels resulted in lower motor type neuropathy and bladder incontinence. Though the patient had autonomic dysfunction of bladder due to the external urethral sphincter dysfunction, dribbling continued through the normal meatus and the weakest fistula tract evidenced by nil post voidal residue. This patient had no bowel incontinence due to intact inferior rectal nerve, a branch of pudendal nerve supplying the rectum.