Pain practice : the official journal of World Institute of Pain
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Case Reports Comparative Study
Comparing partial and total tibial-nerve axotomy: long-term effects on prevalence and location of evoked pain behaviors.
Monophasic (one-time) nerve injuries heal without clinically significant residua in most cases, but rare individuals are left with neuropathic pain, even after seemingly minor lesions. The effects of lesion size on risk for chronic pain persistence are not well understood, particularly as concerns the complex regional pain syndrome, which is defined in part by pain "disproportionate" to the severity of the causative lesion, and extending outside the autonomous territory of a single nerve. To better clarify the expected prevalence of pain behaviors after nerve injury, we compared the effects in rats of different-sized axotomies on the prevalence and location of evoked pain behaviors. ⋯ Soon after surgery, evoked pain behavior developed in the ipsilesional sural-innervated site in a subset of axotomized rats and recovery was variable. The relationship between lesion size and prevalence and severity of hyperalgesia varied for different pain behaviors, with pinprick hyperalgesia clearly more likely after larger axotomies. In summary, partial tibial-nerve injury in rats models human disease and suggests that expectations of proportionality between lesion size and development of neuropathic pain may need revision.
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Editorial Comparative Study
Modeling neuropathic pain: subtlety and susceptibility.