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Neuroradiology Case of the Week

Case 82

Ravinder Sidhu MD, Leena Ketonen MD, PhD,
and P-L Westesson MD, PhD, DDS

Clinical Presentation: A 4-year-old male presented with a history of urinary and stool incontinence.

Radiological Findings:  Sagittal T1 and T2-weighted MR images of the thoracolumbar spine showed complete absence of caudal three sacral segments. The spinal cord showed bulbous end and was seen to terminate at the L1 vertebral level. The rest of the vertebral bodies and discs were unremarkable. Urinary bladder was markedly distended with trabeculations suggestive of neurogenic bladder (Fig. 1A & B).

Diagnosis: Caudal regression syndrome

Discussion: Caudal regression is a rare congenital anomaly of the lower vertebral column, frequently associated with orthopedics deformities, genitourinary, gastrointestinal and neurological malformations. They are characterized by various degrees of absence of vertebrae of the sacral, lumbar and, less frequently, thoracic regions. Maternal diabetes, genetic predisposition and vascular hypoperfusion have been suggested as possible causative factors [1].
     The urological problems are mainly neuropathic bladder with constant dribbling of urine and recurrent urinary tract infections. Lower urinary tract and sexual function is usually compromised, due to involvement of the S 2-4 nerve roots. Abnormalities in the bowel function such as constipation, poor sphincter tone and perianal anesthesia is frequently associated. The severity of the morphological derangement correlates with residual spinal cord dysfunction and with severity of the clinical deficit [1].
     Prenatal ultrasonography is the diagnostic tool of choice of fetal spine for the diagnosis of caudal regression syndrome that can be made by 20-22 weeks of gestation. Transvaginal ultrasonography increases the sensitivity by diagnosing the syndrome at 11-12 weeks of gestation [2].
     MR imaging is the modality of choice as it effectively demonstrates level of vertebral agenesis, position and configuration of spinal cord and also associated anomalies in the pelvis. The conus is usually club-shaped and ending at an unusually high level. The position of conus medullaris defines two distinct groups of patients with sacral agenesis. In the group I, the conus ends cephald to the lower border of L1. It is typically deformed and terminates abruptly at T11 or T12 and is nearly always club-shaped terminating in bulbous shape. In group II, the conus terminalis ends below L1 known as tethered cord [3].

References:

1. Adra A, Cordero D, Mejides A, Yasin S, Salman F, O’Sullivan MJ. Caudal regression syndrome: etiopathogenesis, prenatal diagnosis, and perinatal management. Obstet Gynecol Surv.1994; 49:508-516.
2. Gonzalez-Quintero VH, Tolaymat L, Martin D, Romaguera RL, Rodriguez MM, Izquierdo LA. Sonographic diagnosis of caudal regression in the first trimester of pregnancy. J Ultrasound Med 2002; 21:1175-1178.
3. Unal O, Sakarya ME, Arslan H. The club-shaped cord terminus in siblings with caudal agenesis: MRI. Neuroradiology 1999; 41:735-737.