Direct Nerve Repair

This type of nerve repair is often favoured  when a nerve is sharply cut in half, which would not be expected to recover naturally. A nerve laceration often results in a discrete zone of injury allowing for the two ends of the nerves to be sewn back together using microsurgical techniques. This type of injury is often fixed shortly after the laceration.

Whenever a nerve is transected, whether it is sharply or ruptured (“torn apart”), all of the axons (part of the nerve that sends nerve signals) downstream “fade away“ in a process called Wallerian degeneration. Therefore, whether a nerve is fixed surgically or recovers naturally, it has to regrow down this length to its target. The body regrows a nerve at the rate of approximately 1 mm per day, or 1 inch per month. Therefore, it can take several months to years to realize the final recovery after a nerve is repaired or recovers.

Specifically, when fibres affecting muscles are involved, there is a time window in which nerve fibres have to innervate the muscle prior to permanent atrophy of the muscles and the connection between the nerve and muscle (neuromuscular junction). This time period is approximately 18 months and an important factor considered when choosing the type of reconstruction versus waiting for natural recovery. The sensory fibres of a nerve that are responsible for sensation do not appear to have this time constraint. For best outcome, nerve repair should be done as soon as possible (ideally less than 6 months from injury).

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