This patient was shot through the tibial nerve. A large neuroma-in-continuity is present.
Considering major nerves controlling strength and sensation are present throughout the body, trauma can commonly damage these structures. Nerve injury causes pain, weakness, and numbness. Although some nerve injuries recovery spontaneously, other do not.
For example, if a nerve is cut, stretched apart, or has excessive scar tissue in or compressing the injured nerve, then recovery may not be possible without surgery. Nerve injuries can be classified as sharp transections, blunt transections, and "uncertain".
Sharp injuries include being cut with glass or a box cutter. Sharply cut nerves should be repaired as soon as possible. Blunt injuries can either tear a nerve or cause severe scarring without cutting it. Most nerve transections actually have a blunt component (e.g., propeller blade, saw injuries). Patients with cut nerves that have a blunt component should have their nerves repaired approximately 2-4 weeks later, so that any scarring will be evident and removed before repair. The most common type of nerve injury is the "uncertain" type (e.g., after surgery, blunt or stretch injuries without an open wound). For these patients it is uncertain if they will recover spontaneously or not. Imaging and electrical testing in most cases cannot answer this question. Therefore, the general approach is to wait approximately three months for spontaneous recovery. If no recovery is evident, then surgical exploration is performed.
Surgery is both diagnostic and therapeutic. The nerve is inspected both with a microscope and direct electrical testing. Cut nerves are repaired. Uncut, but scarred nerves that have no electrical response are also repaired, usually by removing the damaged nerve segment and replacing it with a nerve graft (see technology and techniques available section). If electrical function is present, then the nerve is only cleared of scar tissue to allow further recovery. Surgery only optimizes the anatomical situation so that nerve regeneration can occur. Therefore, immediately after surgery your neurological deficit should be the same, however, with regeneration movement and sensation should start to return in 3 to 12 months, depending on the nerve repaired.
Nerve regeneration is not perfect, however, with some patients having only a partial recovery, or even no recovery of function. Some nerves recover better than others. For example the radial and tibial nerves recover exceptionally well, while the peroneal and ulnar nerves do not. Furthermore, as the distance between the injury and the muscle or skin to be reinnervated increases, the chance of a good recovery decreases. Therefore, proximal arm and leg nerve injuries are more problematic. Neuropathic pain usually resolves as reinnervation occurs, but once again, this can take many months. The chance of neurological recovery also depends on the timing of surgery: sooner a nerve is repaired, the better. The usually timing of surgery is 3 to 6 months for "uncertain" injuries. If you wait longer than one year, then the chances of recovery are minimized.
As mentioned, if you do not know if the nerve will recover spontaneous, you wait those first 3 months to avoid unnecessary, and potentially dangerous surgery. It is still important to be evaluated by a peripheral nerve surgeon soon after the injury so that if surgery is an option, you do not miss this opportunity.
