METHODS OF CLOSING GAPS BETWEEN NERVE ENDS
- Mobilization of the nerve ends:
>small gaps can be closed by mobilizing nerve ends for a few cm proximal & distal to the point of injury.
>Extensive dissection of nerve from surrounding tissues & excessive stripping of small vessels to the nerve should not be done as it may disrupt segmental blood supply leading to ischemia & more intraneural scarring.
>Motor & essential sensory branches should be protected
>Gaps distal to the motor branches of a peripheral nerve are closed more easily.
>Excessive tension should always be avoided.
- Positioning of the extremity:
>Relaxing the nerve by flexing joints & by abducting, adducting, rotating, & elevating the extremity.
Excessive flexing limb can cause tension on the neurorrhaphy later & intraneural fibrosis compromising axonal regeneration.
>Knee & elbow flexion not more than 900; Flexion of wrist not more than 400.
>After healing of the wound, the joint can be extended not more than 100 per week until motion is regained.
>Nerve grafting should be preferred to drastic positioning of the extremity to avoid tension on neurorrhaphy.
- Nerve transposition: by changing the anatomical course of nerve & shortening the distance between nerve ends, e.g. ulnar nerve at elbow; median nerve transposing anterior to pronator teres; tibial nerve placing anterior to soleus or, gastronemius etc.
- Bone resection: Rarely used; usually done when bone is already fractured, e.g.resection of humerus if humerus already fractured-to close large gaps in the ulnar, radial or median nerves. But if fracture has healed, osteotomy is more difficult.
- Nerve Stretching & Bulb suture:
>Only gentle traction without too stretching which does not hinder regeneration is recommended
>Stretching of nerves by bulb suture ( neuroma to glioma) with joints acutely flexed followed by progressive extension & later end to end neurorrhaphy by asecond operation.
- Nerve grafting:
>When the defect is caused by loss of nerve tissue & the gap cannot be fulfilled by local mobilization of nerve, joint positioning & primary repair.
Autogenous sural nerve-the preferred source; others-Superficial radial nerve, median nerve, ulnar nerve etc.
- Nerve crossing- pedicle grafting:
>Rarely used in combined median & ulnar nerve injury with very large gaps;
>advised in nerve injury by massive ischemic necrosis of forearm, but nerve grafting seems better than this method.