Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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February 9, 2015
Sacral Agenesis
- Sacral agenesis considered a part of caudal regression syndrome. It is a rare sacral developmental abnormality consisting of absence of part or all of the sacrum.
- It is clinically associated with malformation of the hindgut, caudal spinal cord, lower limbs, and the urogenital system.
- Sacral agenesis has an incidence of 1 in 25,000 live births and is associated with maternal diabetes in approximately 25% cases.
- Renshaw classified sacral agenesis into four types, based on the amount of sacrum remaining and articulation between pelvis and spine.
- Key Diagnostic Features
- Developmental malformations of the caudal spinal cord include sacral meningomyelocele, tethered cord, transistional lipoma, and cauda equina syndrome due to stenosis of the dural sac.
- As seen on MRI, the position of the conus defines 2 distinct groups of patients with sacral agenesis:
- In group 1 the conus is absent and the spinal cord ends with a blunted appearance, cranial to the lower border of the L1 vertebra. In this group the sacrum is completely absent.
- In group 2 there is a tethered cord and the conus is present below L1. In these patients variable parts of the sacrum are present.
- Multiple vertebral anomalies such as fused vertebra, hemivertebra, butterfly vertebra, and diastematomyelia may also be seen.
- Rx Treatment and progression depend on the extent of regression. Management options are often centered around genitourinary and neuromuscular complication with orthopedic input.
