RADIOLOGICAL STUDY OF EXTRA DURAL SPACE

To perform caudal analgesia or anesthesia, it is important to determine the anatomy of sacral hiatus which is the distance between 2 sacral cornuae .The length of hiatus approximately 1/3 length of sacrum.Width of hiatus approximately 1/9 upper breadth of sacrum.1/5 lower breadth of sacrum.The hiatus is covered by sacro-coccygeal membrane that is longer in male than female but it is thicker in female than male.The distance from sacro-coccygeal membrane to dural sac was longer in male than female so care must be considered before introducing the needle in female when performing epidural analgesia or anesthesia and longer needle is needed in male when performing sub arachnoid.If there is congenital variation in sacral hiatus e.g absent or ossified hiatus approach to epidural space is done through sacral foramina.It can concluded that the transforaminal caudal block is easy, simple, safe and effective as transhiatal route and does not require flexion of the spine as in performing lumbar epidural block. The only real difficulty is location of anatomical landmark and this problem can be solved by learning the anatomy.If the transformational approach is obstructed, the lumbar approach is required so congenital spine deformities need to be carefully analyzed to identify the congenital anomaly which stand as a negative point with the accidental intra thecal placement of an epidural catheter which has been reported in needle through needle in combined spinal epidural anesthesia.The outlet projection is the most useful view in plain radiograph for the evaluation of the sacral foramina and pedicles. Quantitative data of sacral foramens anatomic position on the dorsal aspect of the sacrum may be helpful in the sacral pedicle screw placement..