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

ABSTRACT

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. 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. 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 SI- 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. 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