Caudal regression sequence is a rare congenital malformation of the lower spinal segments associated with aplasia or hypoplasia of the sacrum and lumbar spine.
Prevalence is estimated at around 1/50,000 and 1/100,000 of pregnancies. Maternal diabetes is a major risk factor for developing this syndrome, which is up to 200 fold more frequent than in the general population.
There is a spectrum of anomalies of the caudal end of the trunk; malformations vary from isolated partial agenesis of the sacrococcygeal spine to more severe deformities. These developmental anomalies can result in deformities of the pelvis (typically fusion of the iliac wings), anomalies of the lower extremities (i.e. flexion of the knees, varus position of the feet) and motor and neurological deficits of varying degrees of severity (i.e. spontaneous motor activity and impaired deep tendon reflexes of lower limbs). Additional complications of the genitourinary, gastrointestinal and respiratory systems may occur. Genitourinary anomalies can involve unilateral or bilateral renal agenesis, renal ectopia and fused ureters, and generally lead to urinary obstruction, neurogenic bladder, enuresis, or vesicoureteral reflux. Gastrointestinal anomalies can involve inability to control bowel movements (incontinence, encopresis) and an imperforate anus. Congenital heart anomalies are frequently observed. Cases with Chiari I malformation, holoprosencephaly, chronic hypertension and cleft lip and palate have also been reported.
The malformations are believed to result from impaired development of the mesoderm prior to 4 weeks gestation. The etiology seems to be multifactorial as maternal diabetes, vascular hypoperfusion, and genetic predisposition (for example mutation in VANGL1 gene) can lead to the syndrome.
Diagnosis is based on antenatal ultrasound examination in the first trimester of pregnancy in the most severe cases. The severity of the disease is determined by examination of the newborn by means of postnatal ultrasonographic and nuclear magnetic resonance imaging (MRI) examination.
The main differential diagnosis is sirenomelia (see this term). CRS has also been associated with the VACTERL syndrome (see this term). The Currarino syndrome (see this term) is a form of caudal regression syndrome characterized by the classic triad of presacral mass, sacral bone defect and anorectal malformation in which an autosomal dominant inheritance has been described with mutation or deletion of the HLXB9 gene.
Most cases of caudal regression are sporadic or associated with maternal diabetes.
Management requires a multidisciplinary approach by neurosurgeons, urologists, neuphrologists, physical therapists and psychologists. Surgical interventions such as transureteroureterostomy and cutaneous vesicostomy, clean intermittent catheterization and/or anticholinergic drug administration are generally required to treat urological disorders. Colostomy is performed to treat an imperforate anus. Depending on the severity of the syndrome, orthopedic interventions may also be required. Treatment is only supportive because the primary pathology is irreversible.
Prognosis is poor. Early neonatal death in the severe forms occurs from cardiac, renal and respiratory complications. Surviving infants usually have normal mental function.
Last update: April 2010