PRINCIPLES OF SURGICAL MANAGEMENT OF PERIPHERAL NERVE INJURY
Not all peripheral nerve injuries need surgical treatment, but in some cases inappropriate delay of surgery or considering it unnecessary can be a cause of permanent neurological deficit and disability. The selection of patients and the proper timing for an operation in some aspects are controversial.
With proximal brachial plexus injuries, early myelography, or CT and MRI may confirm evidence of nerve root avulsion. In such a case nonoperative management is indicated or an early neurotization procedure may be considered.
For penetrating injuries of the laceration type, early exploration is appropriate. In grossly contaminated injuries, and in nerve transection with ragged ends, the nerve ends should be tagged before wound closure. A delayed repair (2 - 6 weeks) should be planned (end-to-end or nerve graft). If the transection of the nerve is sharp, immediate repair is indicated. Interrupted nerves in cutting wounds need an additional incision to find the two segments of the interrupted nerve. Primary suture is indicated in clean wounds, with a good general condition of the patient permitting complete investigation of motor power and sensation before surgery. For gunshot and other missile injuries, early surgery often is performed to correct the vascular damage. Through the same surgical procedure, the nerve should be exposed and evaluated, eventually repaired. Otherwise surgical exploration in unaffected continuity will be required after 4 - weeks when the manifestations of the neuropraxia are over, and if there are no electrophysiological or clinical signs of improvement.
In closed injury of peripheral nerves, when it appears that the nerve continuity has not been compromised, a period of observation of some weeks will be necessary. If an EMG or clinical evidence of regeneration or recovery is evident over a 12-week period, surgical intervention is most likely not indicated. Partial injury of a nerve trunk is an exception. If, at the time of surgery, the nerve is observed to be transected, an end-to-end of graft repair is performed. If a neuroma or scar tissue distorts or squeezes the nerve, dissection to free the nerve of its confinement (external neurolysis) should be performed. An intraoperative Nerve Action Potential [NAP] recording across the injury site should be recorded before and after the neurolysis. An improvement may be observed immediately. If so, this indicates that at least a moderate chronic neuropraxic component is present.
If the injury is at about 20 cm or more distant from the end organ (muscle), the surgeon should consider follow-up of the patient for another 1 - 2 months. This delay may allow spontaneous recovery to manifest itself and eliminate the need for surgery. In all fractures accompanied by peripheral nerve injuries, an operation is indicated comparatively rarely as, in a majority of cases, a spontaneous recovery occurs.