Development of Neuropathic Pain by Thermal Injury using Radiofrequency Thermocoagulation in a Rat Infraorbital Nerve. |
Sang Min Kim, Cheul Hong Kim, Hae Kyu Kim, Sang Wook Shin |
1Department of Anesthesia and Pain Medicine, College of Medicine, Pusan National University, Busan, Korea. anekch@pusan.ac.kr 2Department of Dental Anesthesia and Pain Medicine, College of Dentistry, Graduate School, Pusan National University, Busan, Korea. |
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Abstract |
BACKGROUND The aim of this study was to investigate the development of neuropathic pain by radiofrequency thermocoagulation on a rat infraorbital nerve (IoN). METHODS Male Sprague-Dawley rats (n = 35) were divided into three groups, consisting of the S, T and sham operation. In the experimental groups, rats were thermocoagulated by subjecting them to 70oC for 60 sec (S group, n = 12) or 20 sec (T group, n = 11) on IoN. In the control group (sham operation, n = 12), IoN was not thermocoagulated. The ipsilateral grooming count and escape threshold by von Frey filament (mechanical allodynia) was measured at 1, 3, 5, 7, 9, 11, 13 postoperative days. After two weeks, a 5% formalin solution was injected into the rat upper lips and grooming time was measured for 45 minutes. RESULTS Grooming count and mechanical allodynia significantly increased in the thermocoalgulation groups (S and T groups) compared to control group (sham operation) for the postoperative days. Nerve injury by radiofrequency thermocoagulation enhanced the grooming time after formalin injection in the rat upper lips. CONCLUSIONS These results lend support to the hypothesis that thermal injury using radiofrequency thermocoagulation can induce neuropathic pain in rat IoN and this type of nerve injury increases the responsiveness of chemical nocieptive stimuli. |
Key Words:
neuropathic pain; radiofrequency thermocoagulation; rat |
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