Revisiting Mechanisms of Extraterritorial Allodynia
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The development of pain following an insult to the peripheral nerve is associated with both peripheral and central nervous system changes that can result in the extraterritorial spread of allodynia and hyperalgesia to non-injured sites adjacent to those innervated by damaged nerves [6, 7]; moreover, ectopic afferent discharges in the injured territory drives ectopic neuronal activity in the spinal cord dorsal horn . Systematic evaluations evaluating the development of widespread allodynia following intradermal capsaicin in human volunteers  and after injury in patients [1, 2, 3] provided several lines of evidence to show a role of central sensitization maintained by peripheral inputs.
Gracely et al.  showed that the local infiltration of lidocaine into the painful foci in four patients with reflex sympathetic dystrophy resulted in the resolution of spontaneous pain and widespread allodynia, suggesting that blocking the peripheral inputs normalizes a component of...
KeywordsPeripheral nerve injury Central sensitization Peripheral sensitization Allodynia Lidocaine
We thank Dr. Gary Bennett for his review of the manuscript.
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Conflict of Interest
No specific funding was required for this work. Drs. Gessner and Sang reports no disclosures that are relevant to this report.
Human and Animal Rights and Informed Consent
This article does not contain any studies with human or animal subjects performed by any of the authors.
- 6.Tal M, Bennett GJ. Extra-territorial pain in rats with a peripheral mononeuropathy: mechano-hyperalgesia and mechano-allodynia in the territory of the uninjured nerve. Pain. 1994;57:375–382.Google Scholar