Chronic peripheral neuropathic pain

Definition

Chronic peripheral neuropathic pain is chronic pain caused by a lesion or disease of the peripheral somatosensory nervous system [1]. The lesion or disease may involve one or more peripheral or cranial nerves, nerve plexus or roots, the dorsal root ganglia or cranial nerve ganglia. The aetiology of conditions associated with chronic peripheral neuropathic pain varies widely. Underlying disease mechanisms include mechanical trauma, metabolic disorders, chemical toxins and drugs, infection, ischemia, tumor growth, autoimmune disorders and gene mutations [2-4]. Persistence or recurrence over ≥ 3 months defines chronic pain. The pain may be spontaneous or evoked, as an increased response to a painful stimulus (hyperalgesia) or a painful response to a normally nonpainful stimulus (allodynia). The diagnosis of peripheral neuropathic pain requires a history of peripheral nervous system injury, e.g., by a nerve trauma, or disease, e.g., diabetic neuropathy, and a neuroanatomically plausible distribution of the pain [5]. Negative (e.g., decreased or loss of sensation) and positive sensory symptoms or signs (e.g., allodynia or hyperalgesia) must be compatible with the innervation territory of the affected nervous structure. Demonstration of the lesion or disease involving the peripheral nervous system, e.g., by imaging techniques, neurophysiological or laboratory tests, confirms the diagnosis of definite peripheral neuropathic pain [5]. Diagnostic Criteria: For the diagnosis of chronic peripheral neuropathic pain, pain must persist or recur for ≥ 3 months and fulfill at least criteria A and D below. Criteria B and C increase the level of diagnostic certainty. A. The pain is characterized by both of the following: A.1 History of relevant neurological lesion or disease A.2 Pain distribution neuroanatomically plausible B. Pain is associated with sensory signs in the same neuroanatomically plausible distribution C. Diagnostic test confirming a lesion or disease of the peripheral somatosensory nervous system explaining the pain D. Not better accounted for by another diagnosis of chronic pain. Comments Negative or positive sensory signs consistent with the distribution of the pain may be sufficient to indicate the presence of a lesion or disease of the peripheral somatosensory nervous system. The clinical examination may be supplemented by laboratory tests, e.g., quantitative sensory testing. Tests that reveal the relevant lesion or disease affecting the somatosensory system may, e.g., consist of surgical or radiological confirmation of nerve compression, nerve conduction study, laser-evoked potentials, blink reflex, or skin biopsy confirmation of reduced nerve fibre terminals. Positive findings in these investigations may provide important diagnostic hints at the source of pain. However, all clinical and diagnostic aspects of the pain need to be considered before assuming causality. If clinical examination or diagnostic testing are performed, and the results are negative, neuropathic pain is unlikely (or less likely). Consider using another chronic pain diagnosis.

Inclusions

• Chronic neuropathic pain after peripheral nerve injury
• Chronic painful polyneuropathy
• Chronic painful radiculopathy

Index Terms