The Red Flags of Neuropathic Pain

Contents

• Introduction
• Neuropathic Pain: An Overview
• The Impact of Neuropathic Pain*
• Abnormal Pain Transmission: The Pathophysiology of Neuropathic Pain*
• The Presentation of Neuropathic Pain*
• Red Flags: When Symptoms Signal Trouble*
• Serious Etiologies of Neuropathic Pain*
• Diagnosis and Assessment*
• Patient History*
• Physical and Neurological Examination*
• Ancillary Studies*
• To Whom to Refer: The Treatment Team*
• Recognizing the Red Flags of Neuropathic Pain: Case Studies*
• Case Study 1*
• Case Study 2*
• Case Study 3*
• Summary*
• References*
• Additional Information*

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Target Audience

This continuing medical education activity has been developed for physicians and pharmacists
treating neuropathic pain.

Purpose Statement

The purpose of this newsletter is to identify the appropriate time to refer patients to neurologists
for neuropathic pain.

Learning Objectives

After completing this activity, participants will be able to:

• Identify patients appropriate for referral to neurologists for neuropathic pain symptoms
• Understand classic and nonclassic clinical “red flags” of neuropathic pain
• Apply an understanding of neuropathic pain to reinforce diagnosis and promote therapeutic
  selections for patients presenting with both common and challenging neuropathic pain
  conditions

Introduction

Neuropathic pain is the result of abnormal transmission of pain signals by the
central or peripheral nervous system.¹ This aberrant pain signaling
differentiates neuropathic pain from other pain types. Indeed, neuropathic
pain often produces distinct symptoms, may occur in the absence of tissue
injury or persist after an injury has healed, and often does not respond to traditional
analgesic drugs.^1,2 An expanding array of adjuvant analgesic agents, including certain
antidepressants and anticonvulsants, has demonstrated efficacy for neuropathic pain in
clinical studies. For most patients with neuropathic pain, careful application of evidencebased
treatment with these nontraditional agents can provide relief. However, a minority
of patients presenting with neuropathic pain may have serious, complicated, or even
life-threatening conditions. Certain key features may indicate the need for immediate and
meticulous assessment and referral to specialists for further investigation and treatment.
These “red flags” include the pattern of presentation, the types of functions affected, the
time course of illness, and association with certain diseases. This tutorial describes the
presentation and mechanisms of neuropathic pain and highlights features of these
disorders that indicate the need for referral to specialists for diagnosis and treatment.

Neuropathic Pain: An Overview

Neuropathic pain is common in both primary care and specialist settings, affecting as
many as 4 million individuals in the United States.^2,3 Neuropathic pain is heterogeneous
in presentation, etiology, pathophysiology, and response to treatment, making it a
particular challenge for clinicians.¹ Traditional analgesics, such as the nonsteroidal
antiinflammatory drugs (NSAIDs), are generally ineffective in neuropathic pain states.²
Despite the availability of other, nontraditional treatments, current strategies fail to
produce adequate pain relief in a substantial proportion of patients, suggesting an unmet
medical need.^4–6

Neuropathic pain represents a wide range of pain syndromes that together share an
underlying nerve injury or dysfunction.¹ Numerous conditions are associated with
neuropathic pain (Table 1); common conditions include diabetic peripheral neuropathic
pain (DPNP) and postherpetic neuralgia (PHN).

A full discussion of the treatment of neuropathic pain is beyond the scope of this review.
Due to its heterogeneity, neuropathic pain must be managed on an individual basis.
Pharmaceutical options for treatment include antidepressants, anticonvulsants, topical
anesthetics, and, as a second-line option, opioids. Evidence-based recommendations for
first-line pharmacologic treatment are summarized in Table 2.⁷

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