What is the role of primary anastomosis and tension avoidance in the treatment of spinal accessory nerve (SAN) injury?

Updated: Feb 09, 2018
  • Author: Rohan R Walvekar, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Answer

The proximal and distal free nerve endings are cut cleanly with a No. 15 surgical blade on a firm, flat background, or with a micro scissor, to prepare the ends for re-approximation. One epineural interrupted suture is loosely placed to bring the nerve ends together. The proximal and distal ends of the nerve fascicles are aligned with trimming, when necessary, so that the ends are not buckling. That is, the fascicle ends should lightly approximate one another in one line, rather than tight approximation leading to misdirected fibers. Subsequent interrupted sutures are placed.

Nerve elasticity causes retraction of the proximal and distal nerve segments after injury. This, in addition to the actual nerve injury, may create tension along the site of anastomosis. This tension must be avoided because it will lead to gaps between approximated fascicular ends. Ischemia and increased scarring are also complications of excess tension. [49] Of note, fixed positioning of the limb to alleviate tension is not recommended because stiffness of the joint may result, as well as nerve scarring and gapping when limb movement is eventually restarted.

Another tension-relieving technique that is now less popular involves extensive freeing of the proximal and distal nerve ends from surrounding soft tissue. Nerve mobilization less than 2 cm has been reported as acceptable and will not increase the risk of nerve devascularization. [51]

The intraoperative matching of corresponding proximal and distal nerve fascicles using anatomical, histochemical, and electrophysiological analysis is not fully described here. The reader is directed to Dvali and Mackinnon (2003) for an in-depth description of these techniques. [49]


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