IOSR Journal of Dental and Medical Sciences (IOSR-JDMS) e-ISSN: 2279-0853, p-ISSN: 2279-0861.Volume 15, Issue 12 Ver. V (December. 2016), PP 01-05 www.iosrjournals.org DOI: 10.9790/0853-1512050105 www.iosrjournals.org 1 | Page A Study of Additional Pair of Sacral Foramina in Eastern Indian Dry Sacra Gyanaranjan Nayak Department of Anatomy, I M S and SUM Hospital, S O A University, Bhubaneswar, Odisha, India. Abstract: Occurence of five pairs of sacral foramina is an anatomical variation which may be due to sacralisation of fifth lumbar vertebra or first coccygeal vertebra. Sacralisation of lumbar vertebra may lead to compression of fifth sacral nerve causing backache and sciatica. It may be associated with prolapse of intervertebral disc above the sacralisation. On the other hand sacralisation of coccygeal vertebra may result in prolongation of second stage of labor and perineal tear. Aim- Tostudy the incidence of fifth pair of sacral foramina and ascertain their clinical importance. Methods and material- Eighty human dry sacra were studied macroscopically and they were observed for additional pairs of sacral foramina. Statistical analysis used-The data was compiled and analysed using Microsoft Excels software. Results- Out of 80 sacra, sixteen numbers of sacra (20%) showed a fifth pair of sacral foramina. Twelve sacra(15%) showed sacralisation of lumbar vertebra whereas four cases (5%) presented with sacralisation of coccygeal vertebra. Conclusion-Wefound variation in the number of sacral foramina in the studied sacra. This knowledge is relevant to the anaesthesiologists for performing trans-sacral nerve blocks. And radiologists should bear this variation in mind while interpretating radiographs of lumbo-sacral region. The knowledge of such variation is also helpful for neurologists and orthopedicians while evaluating back pain. Key Words:Sacrum, Caudal Anaesthesia, Sciatica. I. Introduction The sacrum is a triangular piece of bone wedged between the two hip bones. It is formed by the fusion of five sacral vertebrae constituting four pairs of sacral foramina. The sacrum has a blunt caudal apex that articulates with the coccyx and its wide base articulates with the fifth lumbar vertebra. The fifth lumbar vertebra may fuse with the sacrum which is called sacralisation of lumbar vertebra. And the sacrum may also fuse with the first coccygeal vertebra which results in sacralisation of coccygeal vertebra. Both the cases described above present with five pairs of sacral foramina 1 . Sacralisation of lumbar vertebra may compress the fifth sacral nerve manifesting as sciatica and back pain. Sacralisation may be kept in mind in case of young individuals presenting with back pain.Lumbar sacralisation may pose difficulty in identifying the lumbar level corresponding to an emerging nerve root at the time of spinal block. This makes radiological examination necessary before lumbar epidural injection or selective nerve root block if lumbar sacralisation is suspected 2 . Lumbar sacralisation may not cause nerve root compression by itself 3 . However sacralisation of fifth lumbar vertebra causes an increased risk of early degeneration of the upper intervertebral disc. And the disc herniation may result in development of nerve root symptoms 4,5 . Sacralised fifth lumbar vertebra is associated with poor obstetric outcome. There is delay in engagement of head of the fetus during labor. There are chances of difficult labor as lumbar sacralisation may induce occipitoposterior position. And labor may be prolonged as descent of head takes longer in a longer birth canal 6 . Coccygeal sacralisation has also got its own clinical significance. Coccygeal sacralisation can be the culprit behind the failure of caudal anaesthesia due to passage of the fifth sacral and first coccygeal nerves in the fifth pair of sacral foramina. Coccygeal sacralisation also leads to fixation of the coccyx, as a result of which the anteroposterior diameter of the pelvic outlet cannot be increased during labor. This results in prolonged labor, perineal tear and creates problems in forceps delivery 7 . The knowledge of sacralisation of lumbar or coccygeal vertebra leading to variation in the number of sacral foramina is highly significant for physicians, orthopaedic surgeons, anaesthesiologists and obstetricians. So we undertook the present study to find out the variation in the number of sacral foramina and correlate it with sacralisation.