• Xiaoji Zhou, Yongtao Liu, Jun Ma, Tao Sui, Yingbin Ge, and Xiaojian Cao.
• *Department of Orthopedics, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, China †Department of Orthopedics, the People's Hospital of Suqian, Drum Tower Hospital Group of Nanjing, Jiangsu Province, China; and ‡Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu Province, China.
• Spine. 2014 Apr 15; 39 (8): 635641635-41.

Study DesignAn anatomic study of extradural spinal root in 9 embalmed cadavers.ObjectiveTo ascertain the anatomical parameters of the extradural spinal root and to demonstrate the feasibility of spinal root anastomoses without opening the spinal dura mater.Summary Of Background DataIntradural anastomosis of the spinal root has made breakthrough progress in treating neurogenic bladder in spinal cord injury. However, because of the complex surgical procedures and extensive bony destruction, its clinical use is not widely promoted.MethodsNine formalin-fixed cadavers were used. The distance between the nerve root outlet and ganglion center, the neighboring nerve root-outlet distance, and the gross anatomy of the extradural spinal root were measured with a surgical microscope. The number of nerve fibers from the T7 to S4 ventral roots (VRs) was calculated by immunohistochemical staining.ResultsThe longest and shortest lengths of the extradural spinal root were observed at the S4 and T7 levels, with average values of 33.29 and 6.06 mm, respectively. The longest distance between the adjacent nerve root outlets was observed at L1-L2 (mean, 29.16 mm), and shortest at S3-S4 (mean, 11.79 mm). After leaving the dural sac, the spinal root descends in the spinal canal until reaching the corresponding intervertebral foramina, and the motor nerve roots still lie ventrally to the sensory nerve roots. The largest and smallest numbers of nerve fibers were observed at the L3 and S4 levels (mean, 9169 and 1356, respectively).ConclusionThe dorsal roots and VRs can both be successfully harvested and identified outside the dural sac. The S1 VR can be anastomosed to the S2 VR extradurally without nerve grafts. For extradural neuroanastomosis of the thoracic VRs to the S2 VR, a nerve graft is required. In addition, there are a sufficient number of nerve fibers for functional bladder recovery at the T7-T12 and S1 levels. This study supports the feasibility of extradural spinal root anastomosis as a modified surgical method for treating neurogenic bladder.Level Of EvidenceN/A.

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