The basic aim of treatment of an injured nerve is to restore its function to the best extent possible. In patients whom it is not practically possible, the treatment is aimed at improving the quality of life to the maximum that can be attained. This also requires proper management of the injuries sustained by other tissues like reduction fracture or dislocation.
Non-surgical Treatment and Medication
The role of medical therapy in nerve injury is almost limited to control of pain and inflammation. The pain and inflammation that immediately follows the injury is often controlled with analgesics like NSAIDs. These drugs may be used for a couple of weeks to provide pain relief.
Sometimes corticosteroids may be used to reduce the inflammation or edema (swelling) around the nerve that is compressing the nerve. Acute injury resulting from reperfusion of the traumatized tissue can minimized with use of oxygen under high pressure (hyperbaric oxygen therapy).
A regenerating nerve or abnormally recovered nerve may be associated with neuropathic pain. Neuropathic pain usually responds to some of the antiepileptic drugs and may require prolonged treatment for better results.
Surgical management of the nerve injury is undertaken in patients who show a possible benefit from the procedure. Surgery should not be pursued if the risks outweigh the beneficial effects in these patients.
Several approaches are adopted in surgical treatment of nerve repair. The injury may be repaired within 72 hrs following the injury (primary nerve repair) or it may be done after 2 weeks following the injury (secondary nerve repair). Sometimes a delayed primary nerve repair may be done after 72 hrs but within 2 weeks after the injury. The best results of nerve repair are obtained with direct nerve repair compared to other approaches.
Following all types of nerve repair, the affected part is splinted for at least a minimum of 3 weeks to prevent development of any tension at the sutures. All patients undergoing repair are also monitored regularly for the evidence of nerve regeneration. The follow up is done with nerve conduction studies and neurological examination as explained under diagnosis of a damaged nerve . Tinel’s sign, which is the tingling sensation along the regenerated nerve fibers on gentle tapping, is tested for during neurological evaluation. Tinel’s sign is considered to be a reliable indicator for nerve regeneration.
Primary Nerve Repair
Direct reconnection of the nerve immediately following the injury is called primary nerve repair. This type of repair is possible in clean partial or complete nerve severance. An ideal patient for primary nerve repair is a medically stable patient with a sharp division of nerve and having minimal wound contamination.
The best results from primary nerve repair are seen in purely sensory nerve or a purely motor nerve. The different types of primary nerve repair are perineurial repair, nerve bundle (grouped fascicle repair) and epineurial repair. The repair is done by suturing the nerve ends by different approaches using microsutures.
Individual nerve bundles (fascicles) are repaired by suturing the perineurium in the perineurial repair. This approach is very tedious. It has risk of damaging the nerve in the process of dissection of each fascicle for suturing. Perineurial repair requires several additional sutures than other approaches. This increases the risk of injury to the nerves during the procedure and hence not widely in practice.
Grouped fascicular repair
The aligned groups of fascicles are sutured through the intraneural epineurium in grouped fascicular repair. The result is better when the fascicles are well aligned. This approach can be adopted in crush injuries of nerve or in delayed nerve repair with trimming of nerve ends. For a better understanding of the nerve structure under discussion, refer to the article on nerve injury.
The cut ends of the nerve are aligned and sutured with microsutures through the epineurium in epineurial repair. It is ideal for complete or partial nerve severance. With proper alignment it is also done in sharp laceration (cut) injuries as there is minimal loss of nerve tissue.
Secondary Nerve Repairs
Secondary nerve repairs are done after performing certain additional procedures to facilitate the nerve repair. The additional procedures can include shortening of bones or changing the position of the nerve to adjust the length of the nerve. This allows better approximation of nerve ends with better alignment and a more positive outcome. The repair is usually done with epineurial suture.
Sometimes the nerve repair is delayed by a couple of weeks. In such situations the nerve ends are trimmed during the repair. The repair of a severed (cut) nerve is ideally not delayed more than 4 weeks. Secondary repairs are recommended for contaminated wounds and injuries involving severe tissue damage.
Nerve graft may be required in injuries involving severely damaged nerve or injuries associated with significant loss of nerve tissue. This type of procedure is considered when there is tension on the nerve ends or if there is a gap between the nerve ends. Repair with nerve grafting or by mobilization of the nerve ends to bring them closer is then considered.
Commonly used nerves for a graft include :
- The sural nerve is the most commonly used nerve for autograft (grafting from the same individual) of large nerves.
- The posterior interosseous nerve and the medial antebrachial cutaneous nerve are other donor nerves. These two nerves are suitable for grafting smaller nerves. Allografts (from other individuals) may be used for nerve grafting in some patients after immunosuppression.
The use of autografts show more favorable outcome than allografts.
Other types of surgery
In nerve injuries with gap less than 2 cms, a synthetic absorbable conduit (like polyglycolic conduit) may be used instead of nerve grafting.
In some injuries, the regenerating nerve fibers may get trapped under scar tissue. These fibers may require release from scar tissue by neurolysis.
Tendon transfer surgeries
Failure of nerve repair or irreparable nerve injury is followed up by nerve or tendon transfer procedures. Tendon transfer surgeries are of use in salvaging some of the function of the joint. The procedure involves transferring tendon of a muscle with intact nerve supply to the side with the muscles affected by nerve injury. The contraction of the transferred muscle will partially restore the lost actions of the joint.