What To Think About EMG

  • The levels of some enzymes in the blood may rise when muscle tissue is damaged. These enzymes include aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and creatine phosphokinase (CPK). An EMG can cause higher levels of these enzymes for up to 10 days after the EMG. So blood tests for these enzymes should not be done for 5 to 10 days after an EMG.
  • Special types of electromyograms (EMG) may also be done. For example: 
    • Single-fiber EMG uses very small needles that are put into a muscle. This can show how a single muscle fiber contracts. It is a useful test for myasthenia gravis. This disease affects the nerve-muscle (neuromuscular) junctions.
    • Repetitive nerve stimulation is a useful test for myasthenia gravisand Lambert-Eaton syndrome. In this test, small, repeated shocks are given. The test shows how the muscle reacts to repeated nerve stimulation.
    • External sphincter electromyogram measures the electrical activity of the external urinary sphincter. This helps to find urination problems. The urinary sphincter is a ring-shaped band of muscles around the urethra. It helps control urination. The electrical activity can be measured by skin electrodes, by needle electrodes put through the skin, or by electrodes in an anal plug.

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