ABSTRACT
Objective:To determine the appropriate degree of neuromuscular block (NMB) for abnormal muscle response (AMR) monitoring during microvascular decompression.Methods:Fifty American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients of both sexes, aged 20-64 yr, with body mass index≤30 kg/m 2, who were diagnosed with facial spasm before surgery, scheduled for elective microvascular decompression, were selected.Anesthesia was induced with midazolam 0.05-0.10 mg/kg, sufentanil 0.3-0.5 μg/kg and propofol 1.5-2.5 mg/kg. After patients lost consciousness, electrophysiological monitoring was performed, the zygomatic branch of the facial nerve was stimulated, and the baseline of AMR was recorded in the mental muscle.NMB was monitored with TOF-Watch SX monitor.After rocuronium 0.6 mg/kg was intravenously injected, the amplitude and latency of AMR were measured at different degrees of NMB (100%, 75%, 50% and 25%). The amplitude reservation ratio (the ratio of the amplitude of AMR monitored to the baseline value) was calculated.Linear correlation of the amplitude reservation ratio or latency of AMR with the degree of NMB was analyzed.The criteria for determining the appropriate degree of NMB in AMR monitoring were: 1.amplitude reservation ratio of AMR≥50%; 2.no body movement during electrical stimulatation of facial nerve. Results:No patients had any body movement during electrical stimulation performed at different degrees of NMB.The amplitude reservation ratio ( Y) was negatively correlated with the degree of NMB ( X) ( r=-0.943, t=-42.73, P<0.001), the linear regression equation of the interaction between the degree of NMB ( X) and the amplitude reservation ratio (Y) was Y=90.36-0.894 7 X, and the coefficient of determination R2 was 0.8804 ( F=1825.41, P<0.001). The amplitude reservation ratio ( Y) was positively correlated with the degree of NMB ( X) ( r=0.879, t=28.67, P<0.001) in the latency period, the linear regression equation of the interaction between the degree of NMB ( X) and the latency ( Y) was Y=10.77+ 0.074 3 X, and the coefficient of determination R2 was 0.7681 ( F=821.30, P<0.001). The estimated appropriate degree of NMB for AMR monitoring during microvascular decompression was 25%-45%. Conclusions:The appropriate degree of NMB for AMR monitoring during microvascular decompression was 25%-45%.
ABSTRACT
OBJECTIVE: To evaluate the usefulness of electrodiagnostic studies in hemifacial spasm patients by comparing abnormal muscle response (AMR) and irregular bursting discharge (IBD) before and after the surgery of hemifacial spasm. METHOD: Fifty nine patients who had been diagnosed with hemifacial spasm and underwent microvascular decompression (MVD) were chosen. The AMR was carried out in three different ways; 1) abnormal response of orbicularis oris when stimulating the supraorbital branch of trigeminal nerve (AMR1), 2) abnormal response of mentalis when stimulating the zygomatic branch of facial nerve (AMR2) and 3) abnormal response of orbicularis oculi when stimulating the marginal mandibular branch of facial nerve (AMR3). We identified the correlation between the loss of IBD and the AMR results per each method, the results of the electrodiagnostic studies according to the onset duration, and the point of follow up time. RESULTS: The AMR and IBD decreased or disappeared after the surgery. AMR which had a significant statistical correlation with the changes of IBD, were AMR2 and AMR3. No definite changes were seen regarding the onset duration. According to the studies done during the follow up period, there was a significant reduction in lateral spread and IBD as the length of the follow up period lengthened. CONCLUSION: Investigation of pre- and postoperative electrodiagnostic study, especially abnormal muscle response (facio- facial reflex) is very helpful in predicting the outcome of operation and the overall prognosis.