Development of Neuropathic Pain Model with 1% Phenol Injection in Rat Sciatic Nerve

OBJECTIVE: The purpose of this study is to develop a new neuropathic pain model in the rat. METHOD: Each male adult rat was anesthetized and the sciatic nerve was exposed. Each exposed nerve was injected with 0.03 cc of 1% phenol solution. Normal saline 0.03 cc was injected to the placebo group. Rats were tested for the presence of mechanical allodynia by von Frey hair. Spontaneous pain behavior (paw shaking, paw elevation) was examined for 5 minutes in the cage. RESULTS: Phenol injected group developed allodynia after the second post-injection day for up to 1 month. Allodynia was also observed in the contralateral legs of phenol injected group. The control group did not develop allodynia. Spontaneous pain behavior was not observed in either group. CONCLUSION: Neuropathic pain model was developed by 1% phenol solution injection to the rat sciatic nerve. This study suggests an easier method for making the neuropathic pain model.

Volume-Controlled Histographic Analysis of Pulmonary Parenchyma in Normal and Diffuse Parenchymal Lung Disease: A Pilot Study

PURPOSE: To evaluate the clinical usefulness of a home-made histographic analysis system using a lung volume controller. MATERIALS AND METHODS:Our study involved ten healthy volunteers, ten emphysema patients, and two idio-pathic pulmonary fibrosis (IPF) patients. Using a home-made lung volume controller, images were obtained in the upper, middle, and lower lung zones at 70%, 50%, and 20% of vital capacity. Electron beam tomography was used and scanning parameters were single slice mode, 10-mm slice thickness, 0.4-second scan time, and 35 -cm field of view. Using a home-made semi-automated program, pulmonary parenchyma was isolated and a histogram then obtained. Seven histographic parameters, namely mean density (MD), density at maximal frequency (DMF), maximal ascending gradient (MAG), maximal ascending gradient density (MAGD), maxi-mal descending gradient (MDG), maximal descending gradient density (MDGD), and full width at half maxi-mum (FWHM) were derived from the histogram. We compared normal controls with abnormal groups includ-ing emphysema and IPF patients at the same respiration levels. RESULTS: A normal histographic zone with +/-1 standard deviation was obtained. Histographic curves of normal controls shifted toward the high density level, and the width of the normal zone increased as the level of inspi-ration decreased. In ten normal controls, MD, DMF, MAG, MAGD, MDG, MDGD, and FWHM readings at a 70% inspiration level were lower than those at 20% (p<0.05). At the same level of inspiration, histograms of emphysema patients were located at a lower density area than those of normal controls. As inspiration status decreased, histograms of emphysema patients showed diminished shift compared with those of normal con-trols. At 50% and 20% inspiration levels, the MD, DMF, and MAGD readings of emphysema patients were significantly lower than those of normal controls (p<0.05). Compared with those of normal controls, his-tograms of the two IPF patients obtained at three inspiration levels were located in an area of higher density. CONCLUSION: Using a home-made histographic analysis system which included a lung volume controller, pa-tients with diffuse parenchymal lung disease could be distinguished from normal controls. The method may be useful for the diagnosis and follow up of diffuse parenchymal lung diseases.