[ENG]Electromyography (EMG) and Nerve Conduction Studies (NCS)

CALee Acupuncture

Introduction

In the clinic, patients tend to associate the effects of electroacupuncture treatment with electromyography and pain relief. This post aims to enhance understanding of the examination methods actually performed in hospitals, rather than to confirm the effects or evidence of electroacupuncture.

In actuality, electromyography (EMG) and nerve conduction studies (NCS) are crucial tests for evaluating the function of nerves and muscles. These two tests can diagnose nerve damage or disease, muscle disorders, and neuromuscular junction disorders, as well as determine the extent of these conditions.

What is a Nerve Conduction Study (NCS)?

A nerve conduction study (NCS) is a test that evaluates the function of peripheral nerves. It involves applying electrical stimulation to a nerve and measuring the speed and size of the electrical signals that travel along the nerve. This helps to determine how well the nerve is functioning and whether it has been damaged.

• NCS Procedure

  • Electrodes are placed on the skin over the nerve and muscle being studied.
  • The nerve is electrically stimulated.
  • The nerve's response to the stimulation is recorded and analyzed.
  • Key measurements include amplitude, latency, and conduction velocity.

• Interpretation of NCS Results

  • Amplitude: Related to the number of nerve fibers. A decrease may indicate axonal damage.
  • Latency: The time from nerve stimulation to the onset of muscle response. Prolongation may indicate demyelination.
  • Conduction Velocity: The speed at which electrical signals travel along the nerve. A decrease may indicate demyelination.

• Diseases Diagnosed by NCS

  • Carpal Tunnel Syndrome
  • Ulnar Neuropathy
  • Polyneuropathy
  • Guillain-Barré Syndrome

What is Electromyography (EMG)?

Electromyography (EMG) is a test that records and analyzes the electrical activity of muscles. It involves inserting small needle electrodes into the muscle to measure the electrical signals produced when the muscle contracts or relaxes.

• EMG Procedure

  • Needle electrodes are inserted into the muscle being studied.
  • Electrical activity is recorded while the muscle is at rest and during contraction.
  • The recorded electrical signals are analyzed to assess muscle health.

• Interpretation of EMG Results

  • Normal muscles show little or no electrical activity at rest.
  • Specific patterns of electrical signals occur during muscle contraction.
  • Abnormal electrical signals may indicate muscle disease or nerve damage.

• Diseases Diagnosed by EMG

  • Muscular Dystrophy
  • Myositis
  • Amyotrophic Lateral Sclerosis (ALS)

Similarities and Differences Between EMG and NCS

Both EMG and NCS are used to diagnose neuromuscular disorders, but they differ in their testing methods and what they evaluate.

• EMG: Evaluates the electrical activity within the muscle itself.
• NCS: Evaluates the ability of nerves to conduct electrical signals.

Performing both tests together often provides a more accurate diagnosis.

Conclusion

Electromyography and nerve conduction studies are essential tools for evaluating the function of nerves and muscles. These tests help diagnose a variety of neuromuscular disorders and guide appropriate treatment plans.

References

• Nerve Conduction Studies 
• Electromyography 
• Spinal Radiculopathy
• Electrodiagnostic Examination