A Complete Non-fusion of Sacral Spines- a Rare Anomaly: A Case Report

Abstract

Background: Human sacrum is a large triangular bone formed by fusion of five separate sacral vertebrae and their intervertebral disc. The dorsal surface of sacrum presents triangular sacral canal formed by fusion of sacral vertebral foramina. The opening present at the caudal end of the sacral canal is known as sacral hiatus. Sacral hiatus is formed due to failure of fusion of lamina and spinous process of fifth or fourth sacral vertebrae. Spina bifida occulta is a condition resulting due to incomplete fusion of neural arch of vertebrae, mainly in lumbosacral region. When the condition of spina bifida occulta occurs in the sacrum, the level of non-closure becomes variable. Materials and Methods: A dry human sacrum with full agenesis of the dorsal wall of the sacral canal was identified during regular osteology demonstration lessons for undergraduate BAMS students at Department of Sharir Rachana (Anatomy), Ayurveda Campus, Institute of Medicine, Tribhuvan University, Kathmandu, Nepal. Non-metric differences in spines were thoroughly examined. Results and Discussion: Spina bifida is the generic term for range of discrete defects of neurulation and subsequent vertebral formation. The various forms of neural tube and vertebral defects have been reported such as craniorachisis, anencephaly and myocele. In this case a spine with complete sacral spina bifida occulta was discovered. The posterior laminae of all sacral vertebrae were completely unfused in this specimen. It's more likely that the sacral region was a groove than a canal. There were no additional abnormalities discovered. Many studies on incidence of spina bifida occulta have been published with mixed results. The frequency reported by researchers and population varies substantially. Conclusion: The complete agenesis of the dorsal wall of the sacral canal in these variants is critical for diagnosing lower back pain, sciatica, and caudal regression syndrome, as well as avoiding problems from caudal epidural block and other spinal procedures, such as screw placement for spinal fusion.