22 - Treatment of neuropathic pain

Summary

INTRODUCTION

Neuropathic pain is defined by The International Association for the Study of pain (IASP) as pain following a primary lesion or dysfunction of the nervous system. It is caused either by peripheral damage with lesions involving peripheral nerves, dorsal root ganglia and the dorsal roots (peripheral neuropathic pain) or by central damage, which may involve injury caused by infarction or trauma of spinal cord or brain (central neuropathic pain).

Neuropathic pain results in persistent pain syndromes that have no biological function, but are difficult to treat and cause great distress to the individual. Neuropathic pain is also referred to as neurogenic pain, deafferentation pain, neuralgia, neuralgic pain and nerve pain.

Neuropathic pain may develop immediately after a nerve injury or after a variable interval. It may be maintained by factors different from the initial cause. It can persist for a long time and is frequently not explained by underlying pathology. Patients are frequently seen by many different specialists and their treatment often fails to resolve the pain. As the pain persists other factors such as environmental, psychological and social stressors become relevant contributors to the overall presentation.

PRINCIPLES OF TREATMENT

Treatment of neuropathic pain is not straightforward. The pain is often refractory to conventional analgesic regimens such as Non-Steroidal Anti-Inflammatory Drugs (NSAIDs). Opioids have only limited efficacy in neuropathic pain as outlined later in this chapter; therefore so called co-analgesics, medications which are not typically used as analgesics, are often the first-line treatment of neuropathic pain.