Why it's done

Your doctor may order an EMG if you have signs or symptoms that may indicate a nerve or muscle disorder. Such symptoms may include:

• Tingling
• Numbness
• Muscle weakness
• Muscle pain or cramping
• Certain types of limb pain

EMG results are often necessary to help diagnose or rule out a number of conditions such as:

• Muscle disorders, such as muscular dystrophy or polymyositis
• Diseases affecting the connection between the nerve and the muscle, such as myasthenia gravis
• Disorders of nerves outside the spinal cord (peripheral nerves), such as carpal tunnel syndrome or peripheral neuropathies
• Disorders that affect the motor neurons in the brain or spinal cord, such as amyotrophic lateral sclerosis or polio
• Disorders that affect the nerve root, such as a herniated disk in the spine