BACKGROUND AND OBJECTIVES: Vestibulospinal reflex (VSR), which is measured in static state, tends to be compensated prior to vestibule-ocular reflex. Therefore, by establishing method that enables to track and observe quantified VSR, the reliability of experiment is attempted to be increased. MATERIALS AND METHODS: On five SD Rats to measure electromyogram (EMG), electrodes, in the form of stranded cables composed of seven wires, are chronically implanted on both sides of the soleus muscles. Pre and post operative condition of sitting still, standing, and ladder step walking was compared before, and six and twenty four hours after a unilateral labyrinthectomy with quantified muscle activity in maximal voluntary activity. Simultaneously by using multi modality electric potential plus package, the muscle activity between the two legs was tracked and compared. RESULTS: In the sitting still position, the left/right soleus muscle activities were 25.7/26.0 microV before a unilateral labyrinthectomy which was changed after the surgery with the value of 23.1/8.1 microV and 23.4/14.3 microV when six and twenty four hours passed respectively. In the standing position, 92.8/124.0 microV of preoperative value was changed to 89.6/37.3 microV six hours after the unilateral labyrinthectomy, and it was 97.0/54.7 microV 24 hours after. The preoperative value in ladder step walking test was 56.2/86.0 microV, and postoperative ones were 54.9/21.2 microV and 55.7/38.0 microV after six and twenty four hours respectively. CONCLUSION: VSR assessment method by using quantitative EMG well reflects the process of vestibular compensation, and to maintain the tension of extensor muscles, ladder step walking test is shown to be useful.
Animals ; Compensation and Redress ; Electrodes ; Leg ; Muscle, Skeletal ; Muscles ; Rats ; Reflex ; Track and Field ; Walking

Purpose: Risk factors predicting distant metastasis (DM) in extrahepatic bile duct cancer (EHBDC) patients treated with curative resection were investigated. Materials and Methods: Medical records of 1,418 EHBDC patients undergoing curative resection between Jan 2000 and Dec 2015 from 14 institutions were reviewed. After resection, 924 patients (67.6%) were surveilled without adjuvant therapy, 297 (21.7%) were treated with concurrent chemoradiotherapy (CCRT) and 148 (10.8%) with CCRT followed by chemotherapy. To exclude the treatment effect from innate confounders, patients not treated with adjuvant therapy were evaluated. Results: After a median follow-up of 36.7 months (range, 2.7 to 213.2 months), the 5-year distant metastasis-free survival (DMFS) rate was 57.7%. On multivariate analysis, perihilar or diffuse tumor (hazard ratio [HR], 1.391; p=0.004), poorly differentiated histology (HR, 2.014; p < 0.001), presence of perineural invasion (HR, 1.768; p < 0.001), positive nodal metastasis (HR, 2.670; p < 0.001) and preoperative carbohydrate antigen (CA) 19-9 ≥ 37 U/mL (HR, 1.353; p < 0.001) were significantly associated with inferior DMFS. The DMFS rates significantly differed according to the number of these risk factors. For validation, patients who underwent adjuvant therapy were evaluated. In patients with ≥ 3 factors, additional chemotherapy after CCRT resulted in a superior DMFS compared with CCRT alone (5-year rate, 47.6% vs. 27.7%; p=0.001), but the benefit of additional chemotherapy was not observed in patients with 0-2 risk factors. Conclusion Tumor location, histologic differentiation, perineural invasion, lymph node metastasis, and preoperative CA 19-9 level predicted DM risk in resected EHBDC. These risk factors might help identifying a subset of patients who could benefit from additional chemotherapy after resection.