Complications of regional anesthesia: nerve injury and peripheral neural blockade.

Nerve injuries have been described as clinical, anatomic, or laboratory findings, consistent with damage to discrete elements of the peripheral nervous system. This rather broad definition of nerve injury has several important implications. For example, a patient may develop a subjective sensory or motor deficit (“clinical findings”) although there are no laboratory tests or studies that confirm the injury actually exists. Alternatively, although a study or test may reveal an abnormality (“laboratory findings”), the patient may not perceive sensory or motor deficits. The significance of the nerve injury often depends on three factors. The first is the quality and severity of the sensory or motor deficit. This may range from mild dysesthesias that are barely noticeable, to severe pain, numbness and weakness that may interfere with activities of daily living. The second is the duration of the clinical symptoms. Most of nerve injuries reported with peripheral nerve blockade are transient phenomena. However, long term, permanent injuries have been reported, and can be devastating. The third factor is the patient in whom the nerve injury occurs. Some injuries may be no more than a mild nuisance to an elderly individual, but a catastrophe to a professional athlete or musician. Most published studies do not elaborate on the patient characteristics of those suffering nerve injuries. Therefore, it is important to consider any degree or duration of symptomatic nerve injury as potentially significant.