Measurement of Inter-Laminar space using ultrasound for the prediction of ease of lumbar epidural procedure : A cross sectional study.

Epidural anaesthesia is anaesthesia obtained by blocking spinal nerves in the epidural space as the nerves emerge from the dura and then pass into the intervertebral foramina. In 1885, corning performed first epidural anaesthesia with cocaine for relief of pain in an extremity, it was apparently accidental.

In 1895, cathelin used epidural anaesthesia in sacral region which is now called as caudal analgesia. In 1921, F. Pages performed epidural anaesthesia in his surgical practice. In 1949, Curbelo first performed continuous epidural anaesthesia by means of ureteral catheter.

Epidural anaesthesia is used to provide effective intraoperative and post operative analgesia. A segmental block is produced chiefly of spinal sensory and sympathetic nerve fibers. Motor fibers may be partially blocked.

Standard epidural catheterization techniques namely the loss of resistance and saline drop methods rely on palpation of surface anatomy and the experience of the anaesthesiologist.

Ultrasound assisted CSE anaesthesia technique provides improved precision and efficacy,overcoming the technical difficulties of performing neuraxial blocks.

In 2001,Grau et all reported that preprocedure ultrasonography reduced the number of puncture attempts needed to establish epidural analgesia in women with risk factors for difficult neuraxial block insertion.There is significant evidence supporting the role of neuraxial ultrasound in improving the precision and efficacy of neuraxial anesthetic techniques.

Multiple CNB attempts in difficult epidural procedures increase morbidities such as trauma, pain, higher incidence of post-dural puncture headache, paresthesia, spinal hematoma and failure. A five point score was created to predict DEP but there is no evidence of USG based parameter for prediction of ease of epidural procedures. The working space for the epidural procedure between two adjacent vertebrae can be divided into the interspinous and interlaminar spaces. The interlaminar space is bounded by the bases of the spinous processes, laminae, inferior articular processes, and superior articular processes. Interlaminar space can be identified and measured easily using USG due to its anatomical advantage.Information regarding USG assisted epidural insertion using interlaminar space measurement for prediction of ease of epidural procedure is minimal/nil in literature. Hence, we propose to measure the interlaminar distance using USG to find its correlation with ease of epidural.