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INTRODUCTION

ESSENTIALS OF DIAGNOSIS

  • Consider posttraumatic neuralgia (PTN) when an injury causes unexpectedly severe or prolonged distal pain.

  • Injuries that appear minor, eg, phlebotomy, sometimes injure nerves disproportionately.

  • Symptoms can be mild and transient, moderate, or severe and prolonged. Children almost always recover.

  • The complex regional pain syndrome (CRPS) diagnosis requires additional symptoms: eg, asymmetric edema, alterations of cutaneous blood flow or sweating patterns, or movement difficulties.

  • Full CRPS develops only in the limbs.

  • Rare cases that are prolonged, bilateral, or not associated with trauma may be related to internal structural causes, underlying systemic inflammation, immune dysregulation, or to small-fiber polyneuropathy. These cases require additional diagnostic approaches and often have specific treatments.

General Considerations

Neuralgia refers to pain caused by injury to nerves rather than other tissues. Complex regional pain syndrome (CRPS) is consensus nomenclature that describes a collection of symptoms in a body region influenced by one or more damaged nerves. Chronic excess pain, often burning, is the cardinal symptom. Symptom onset usually occurs within days of injury. CRPS is likely amplified form of posttraumatic neuralgia (PTN) that includes nonpain symptoms (Table 12–1). Full CRPS develops only in limbs, for reasons that are not entirely clear. In contrast, PTN can develop at any site in the body. By definition, PTN and CRPS are incited by trauma, usually external, but in rare cases the causes are internal. For example, a nerve entrapment or infarction can lead to CRPS. The epicenter of symptoms is usually distal to the injury, reflecting involvement of nerves, blood vessels, and sometimes bone. Symptoms are disproportionate to the external signs of injury which can occur, for example, in venipuncture, when nerve twigs encircling blood vessels might be transected by the needle. Three-fourths of CRPS patients are female, and the median age at onset is in the 40s. CRPS is rare in young children and the elderly. Most patients and virtually all children recover spontaneously. Prolonged or severe CRPS is uncommon but profoundly disabling when it occurs. It should provoke search for complicating endogenous factors that impede healing and require additional treatment for resolution.

Table 12–1.The 2012 IASP criteria for complex regional pain syndrome (CRPS).

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