Outcomes for peripheral nerve entrapment syndromes. (2006)

Peripheral nerve entrapment lesions are common clinical disorders. Despite this fact, many neurosurgeons do not have vast training or experience in the diagnosis and management of patients with peripheral nerve entrapments or do not treat these patients because of lack of interest or referral patterns. There are many other reasons to develop a niche for this area of neurosurgery and to incorporate this into one’s training and practice. Peripheral nerve surgery is more than a time honored part of neurosurgical heritage. It is a dynamic subspecialty encompassing a wide range of pathology: entrapments (the most frequently treated), traumatic lesions, tumors, and the like. The management of patients who are successfully diagnosed with entrapments can be especially rewarding. It is a discipline centered on anatomic and pathoanatomic principles. Recent advances in diagnostic tools, treatments, and experimental studies have served as catalysts to fuel the excitement. Currently, conditions that are difficult to diagnose or those that are undiagnosed are still ripe for investigation in the future. Although compression neuropathies typically affect certain nerves at specific sites (e.g., fibroosseous tunnels), any nerve may be compressed anywhere along its course. Entrapment neuropathies share a common pathophysiology (namely, localized ischemia from mechanical pressure) and pathogenesis. A set of well accepted tunnel syndromes has been described, including the most common carpal tunnel and cubital tunnel syndromes. Patients present with a predictable pattern of neurological symptoms (pain, sensory, motor complaints) specific to the affected nerve. The diagnosis can often be made by pattern recognition from a detailed clinical history and physical examination, and confirmed with electrical studies and/or imaging studies. The diagnosis of these entities is relatively easy when the following are present: a classic history, a characteristic physical examination (supplemented with certain provocative tests), and electrodiagnostic studies that are positive or imaging modalities that are revealing. Typically, nonoperative therapy is recommended for at least 3 months and consists of a trial of anti-inflammatory or pain medication, splinting, avoidance of exacerbating activities or positions, physical therapy, and local steroid injections. If worsening symptoms (despite nonoperative treatment), severe symptoms, or advanced findings (i.e., significant atrophy) are observed at the time of initial presentation, operative intervention should be considered. Surgery consists of decompression of the nerve, combined, at times, with other procedures to provide a better path of or bed for the nerve (e.g., transposition). This chapter will review the diagnosis, management, operative intervention, and outcomes in a spectrum of common and controversial entrapment lesions. To remain somewhat of a purist, I have decided to exclude other types of compressions, most notably mass lesions from the discussion. As the reader will see, the common and the controversial will converge in answering the questions of, for example, how to best diagnose or treat the common entrapments; whether or not certain groups of patients with neurologic conditions should be operated, some with a predictable favorable outcome (i.e., inflammatory conditions) and others with a progressively deteriorating course (metabolic); whether or not certain groups of patients with unexplained pain have entrapments (in fact, whether or not certain entrapments exist at all); and, finally, what are the outcomes really and how do we interpret them? In the end, one must consider exactly what and whom he or she is treating.