A 22-year-old woman visited our clinic with a history of radiofrequency volumetric reduction for bilateral masseter muscles at a local medical clinic. Six days after the radiofrequency procedure, she noticed a facial asymmetry during smiling. Physical examination revealed immobility of the mouth drawing upward and laterally on the left. Routine nerve conduction studies and needle electromyography (EMG) in facial muscles did not suggest electrodiagnostic abnormalities. We assumed that the cause of facial asymmetry could be due to an injury of zygomaticus muscles, however, since defining the muscles through surface anatomy was difficult and it was not possible to identify the muscles with conventional electromyographic methods. Sono-guided needle EMG for zygomaticus muscle revealed spontaneous activities at rest and small amplitude motor unit potentials with reduced recruitment patterns on volition. Sono-guided needle EMG may be an optimal approach in focal facial nerve branch injury for the specific localization of the injury lesion.
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Method: Electrodiagnostic data of 152 patients who had been diagnosed as lumbosacral radiculopathy with the findings of operative record were obtained retrospectively. The findings of needle electromyography were reviewed and the frequency of abnormal spontaneous activities in L5 and S1 myotomes was investigated. We selected 8 individual muscles which had high sampling rate. These muscles were combined into different muscle screens and the detection rates were calculated that the frequency with which one or more muscles in the screen displayed abnormal spontaneous activity was divided by the total number of radiculopathies.
Results: The detection rates of lumbosacral radiculopathy were compared according to the number of muscle screens. Including paraspinal muscle, the detection rate of 6 muscle screens was higher than 5 muscle screens (p＜0.05), but there was no significant difference of detection rate between 6 muscle screens and 7 muscle screens. The detection rates of each muscle screens without paraspinal muscle were lower than those including paraspinal muscle for all screens (p＜0.05).
Conclusion: Although there is controversy about selection of muscles, six muscle screen including paraspinal muscles may be optimal number for detecting lumbosacral radiculopathy. (J Korean Acad Rehab Med 2003; 27: 63-69)
Objective: The purpose of this study was to investigate the dose-dependent responses to botulinum toxin A (BTX-A) injection on compound muscle action potential (CMAP) amplitude and needle electromyography (EMG) in local and distant muscles.
Method: The BTX-A (Botox®, Allergan Co.) was injected to the left tibialis anterior (TA): 2, 4, 6, 8 U for each 4 Sprague-Dawley rats; 5, 10, 15, 20 U for each 2 rats. The sciatic nerve conduction and needle EMG were performed in the right and left TA immediately before BTX-A injection, on 2 days after injection, weekly for 1 to 10 weeks, and then monthly for 4 months.
Results: The range of dose-dependent maximal paralysis of the injected muscle was from 94% to 99.2% on 7 days after injection. With the lapse of time, the amplitudes in the left sciatic nerve conduction recovered, the abnormal spontaneous activities disappeared, and the power in spectral analysis of motor unit action potential increased. The range of dose-dependent reductions of the CMAP amplitude of the right TA was from 41.8% to 69.9% in the distant muscle, but there was no abnormal spontaneous activity in needle EMG study. As higher doses of BTX-A were injected, the degree of amplitude reduction became larger and the duration of amplitude reduction became longer in both local and distant TA muscles.
Conclusion: We observed the dose-dependent muscle paralysis with injection of BTX-A. The systemic effects by local injection were induced and the durations of local and systemic effects were proportional to the BTX-A dosage.
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