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Neuroradiology Case of the Week

Case 443

September 2009

Balasubramanya Kolar, MD and P-L Westesson, MD, PhD, DDS

Clinical Presentation: A 50-year-old female presented with progressive leg weakness.

Imaging Findings: MR imaging showed hypoplastic sacrum with spina bifida at S1 level. There was also an abrupt termination of the spinal cord in a wedge-shape above L1 level. A cystic dilatation of the conus was noted.

Diagnosis: Caudal regression syndrome

Discussion: The syndrome of caudal regression is composed of various anomalies such as sirenomelia, lumbosacral agenesis, and exstrophy of urinary bladder [1]. The lack of formation of caudal spinal cord and spinal column has been hypothesized to be due to toxic, infectious or ischemic insults. The timing of the insult has been postulated to be before the fourth week of gestation [2]. Hyperglycemia is also considered a possible etiological factor. Approximately one-sixth of these infants are born to diabetic mothers.

There is a classification of the syndrome into two group:
Group I:	More severe caudal dysgenesis with high lying, club-shaped terminal part of cord. The cord ends above L1 with distal wedging associated with severe malformations of sacral vertebrae. There may also be a dilated central canal or a conus CSF cyst.
Group II:	Less severe dysgenesis compared to the earlier group. There is usually a low lying tethered cord with a lipoma or lipomyelomeningocele.The conus terminates below L1 and tethering is more common [3].

     The imaging findings in the case presented indicate that it belongs to Group I with termination of conus above L1, a wedge-shaped abrupt termination, conus cyst and severe anomalies of sacral vertebrae.
     The natural history and prognosis is variable and depends on severity. Surgical untethering, release or duraplasty are procedures that may be necessary to improve neurological function [3].

References:

1. Congenital anomalies of spine. In: Pediatric Neuroimaging. Barkovich AJ, Ed. 4th ed. Lippincott, Williams and Wilkins: Philadelphia, 2005: 704-772.
2. Duhamel B. From the mermaid to anal imperforation: the syndrome of caudal regression. Arch Dis Child. April 1961; 36:152-155. [PDF]
3. Congenital and developmental disorders. In: Diagnostic Imaging: Spine. Ross JS, Brant-Zawadzki M, Moore K, et al., Eds. Utah: Amirsys, 2004: 32-35.