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WCB for health care providers > Medical advisory guidelines > Medical advisory guideline specifics >Electromyography (EMG) and Electroneurography (NC)

Electromyography (EMG) and Electroneurography (NC) - E2.1

Definition of condition:  Electromyography (EMG) is an electrophysiologic study performed to determine the electrical activity of specific muscles to assist in diagnosing muscular diseases and the effects of other diseases on muscles.

Electroneurography (NC) is the measurement of the conduction velocity and latency of peripheral nerves.

Issue statement: These two studies are usually combined and serve as laboratory tools in the diagnosis of nerve and/or skeletal muscle trauma or disease.

EMG measures skeletal muscle activity during rest and during voluntary muscle contraction.  A comparison and analysis of the amplitude, duration, number, and configuration of the muscle activity enables disorders of the motor units to be detected and characterized as either neurogenic or myopathic.

EMG and nerve conduction studies can help determine the site of a nerve injury (e.g. distinguish between a peripheral nerve and a nerve root lesion).  They do not assess sensory nerve impairment.

WCB-Alberta position

Payment for EMG and nerve conduction studies are approved when the tests are recommended by a consultant and/or Unit Medical Advisor to evaluate a compensable injury.

Comments

EMG/nerve conduction studies in conjunction with clinical examination findings and results of laboratory studies may be sufficient to make a specific etiologic diagnosis.

EMG/nerve conduction studies may:

  • corroborate a diagnosis or refute additional possibilities within a differential diagnosis
  • provide a guide to the severity of an acute disorder of a peripheral or cranial nerve
  • indicate that a pathologic process is active or progressive in chronic or degenerative disorders.

Normal EMG/nerve conduction studies do not necessarily rule out nerve impairment as these studies cannot detect impairment of sensory nerves.

The major indications for EMG and nerve conduction studies include:

  • Monitoring and evaluating myopathies or neuropathies
  • Determining if muscle pathology is caused by drugs or toxins
  • Investigating primary muscle diseases affecting striated muscle fibers or cell membranes: muscular dystrophy, myasthenia gravis
  • Investigating secondary muscle disorders caused by polymyositis, sarcoidosis, hypocalcemia, thyroid toxicity, tetanus, and other disorders
  • Investigating neuromuscular disorders such as peripheral neuropathy caused by diabetes or alcoholism
  • Investigating muscle disorders caused by diseases of the lower motor neurons , i.e. the motor neurons in the anterior horn of the spinal cord: anterior poliomyelitis, amyotrophic lateral sclerosis, amyotonia, or tumors
  • Investigating muscle disorders caused by diseases of the lower motor neuron involving the nerve root: Guillain-Barre, herniated disc, spinal stenosis
  • Differentiating between primary and secondary muscle disorders or neuropathy and myopathy as revealed by differences in the amplitude, duration, number, and configurations of the electrical activity.

Work relationship criteria

The region to be examined must be included in the region of injury/disease accepted by the WCB.

Clinical criteria for acceptance of responsibility

Medical reporting documenting objective clinical or laboratory findings and requesting the need for an EMG.

WCB requirements for arranging expedited examinations

Rapidly progressing symptoms and/or suspected or obvious muscle wasting.

Criteria for denial of responsibility

Evaluation of non-compensable conditions.

Authorization

The Unit Medical Advisor on request by the attending physician.

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