The prevalence of spina bifida occulta in Pakistani population: A study of dry human sacra

Abstract

Introduction: Spina bifida is an important developmental defect of vertebral column. There are various types of spina
bifida. The commonest one is spina bifida occulta (SBO), in which patients do not show any sign and symptoms as there
is no herniation of spinal canal contents. This lesion is present at birth. Incidence of spina bifida decreases with age. The
prevalence of spina bifida is related to various factors. Genetic predispositions, environmental factors and teratogenic
effects of the drugs are important. It may be caused by the prenatal use of drugs like valproic acid. Sacral hiatus is used
for caudal epidural block. We conducted this cross sectional study to find out the incidence of SBO in our population.
Methodology: This was an observational descriptive study. This study was carried out in Islamic International Medical
College Rawalpindi. The duration of study was six months. Bones were studied in five different medical colleges of
Rawalpindi with the consent of the concerned authorities. A total of 200 sacra were selected. The damaged and defective
bones were excluded. All the studied bones were complete. All bones were studied for prevalence of SBO in our
population. Bones having apex of sacral hiatus till S4 were considered normal. The remaining bones were divided into
four grades according to level of failure of closure of sacral laminae. Bones with partial closure between two or more
adjacent sacral vertebrae (incomplete spina bifida) were included in Grade I and II. Bone with sacral hiatus extending
beyond S4 ( long hiatus)were included in grade III and all bones with open dorsal wall representing the complete failure
of fusion of the laminae from S1-S5 were included in grade VI. Results were analyzed by SPSS 17.
Results: The spina bifida was found in 69 bones with an overall incidence of 34.5% among 200 bones. Out of 69
variants, bones were grouped in two groups; one having complete and incomplete SBO among adjacent vertebrae, other
having long hiatus. Prevalence of grade-1 SBO was 5.5% while it was 4.5% for grade- IV SBO. Region between S1- 2
was the most common site for grade-1 anomaly. Incidence of long hiatus from S5-3 was higher i.e., 46 (23%) while 2
sacra had hiatus ending at S2.
Conclusion: Presence of spina bifida occulta should always be kept in mind while dealing with patients of backache,
urinary and neurological symptoms. It may also be the cause of failure of caudal epidural block. Studies with larger
sample size and including different ethnic groups from different regions of Pakistan are required to note the regional
and ethnic disparities in the anatomy of the sacral hiatuses.