Abstract
Background and Objectives: In addition to EMG and muscle biopsy, measurement of muscle enzymes is helpful in diagnosing of neuromuscular disorders. Therefore, possible effects of needle EMG on serum levels of muscle enzyme are of importance. Although several studies addressed the question whether needle EMG causes elevation of muscle enzymes (creatine phosphokinase [CKP] and lactatedehydrogenas [LDH]) the results were conflicting. However, these studies used srerilizable needle – electrodes and different protocols and methods to record EMG and determine muscle enzymes. We investigated prospectively whether muscle enzymes are elevated after sterilizable concentric needle EMG.
Materials and Methods: In 70 subjects who attended the electrodiagnosis unit of physical medicine and rehabilitation department of Imam Khomeini hospital in Tabriz for an EMG investigation were studied between June 2003 and February 2004. Blood sampling and muscle enzymes were determined immediately following EMG with sterilizable concentric needle electrodes. Subjects with hypercratinephosphokinemia as a result of other neuromuscular disorders were excluded.
Results: Seventy subjects, 28 women and 42 men, aged 17-72 years (mean 36.1 year) were studied and the number of investigated muscle was between 2-17(mean 5.5) per subject. Wilcoxon signed ranks test was applied due to the abnormal distribution. We obtaited the following results:
• Serum LDH value was increased before and after EMG, but the difference was not statistically significant.
• There was no difference in serum CPK value before and after EMG.
• Difference of serum CPK value would be significant if more than 5 muscles were investigated.
Conclusion: EMG with sterilizable concentric needle electrodes does not cause false – positive results for muscle enzyme serum levels.