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Understand physiology and coding for EMGs and nerve conduction studies

JustCoding News: Outpatient, November 4, 2009

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by Lois E. Mazza, CPC, PCA

Electromyography, commonly known by the acronym EMG, is a neurological test physicians use to measure and record the electrical activity of muscles at rest and when contracted.

Nerve conduction studies measure and record how well and how fast muscles can send electrical signals.

Tests help identify disorders and causes of certain symptoms

Physicians may perform an EMG to diagnose certain disorders that damage nerves, muscle tissue, and the neuromuscular junction (where nerves and muscle meet). These disorders include the following:

  • Herniated disks
  • Amyotrophic lateral sclerosis
  • Myasthenia gravis

Physicians may also perform an EMG to diagnose the cause of certain symptoms, such as weakness, paralysis, or muscle twitching. These symptoms result from problems in the following:

  • A muscle
  • The nerves supplying a muscle
  • The spinal cord
  • The area of the brain that controls a muscle

However, an EMG will not show brain or spinal cord disease.

Physicians perform nerve conduction studies to diagnose damage to the peripheral nervous system, which includes all the nerves that lead away from the brain and the spinal cord as well as the smaller nerves that branch out from these nerves. Some common diseases that affect the peripheral nervous system include carpal tunnel syndrome and Guillain-Barre syndrome.

When administering EMGs, a specially trained technician places a very thin electrode needle into the muscle through the skin. The muscle activity is then displayed on a special monitor called an oscilloscope. Muscle activity can also be heard. The wire used for the study has a tiny microphone on the tip. A very thin wire, too small to be seen with the naked eye, runs through the middle of the testing wire. The microphone picks up the electrical sounds the muscles make, and certain characteristics of these sounds help physicians to diagnose and assess the patient’s condition or illness.

Electricity governs bodily functions

To understand electricity in the body, consider some basic cellular anatomy and physiology regarding electrical activity in cells.

All matter is made of molecules, which are in turn made of atoms. All atoms contain:

  • Protons, which have a positive charge
  • Neutrons, which have a neutral charge
  • Electrons, which have a negative charge

The reaction from these charges moving into and out of atoms creates electricity in the body, and it’s this electricity that governs bodily functions, including muscle movement and your heartbeat.

Diagnoses and symptoms for which the tests are administered

Note the following codes for common diagnoses and symptoms for which physicians may order EMGs and nerve conduction studies:

  • 333.0: Other degenerative diseases of the basal ganglia (Shy-Drager syndrome)
  • 334.0: Friedreich's ataxia
  • 335.20: Amyotrophic lateral sclerosis (ALS)
  • Peripheral neuropathy:
    • 337.0x: Idiopathic peripheral autonomic neuropathy
    • 337.1: Peripheral autonomic neuropathy in disorders classified elsewhere
      Code first underlying disease as:
      Amylodosis (277.30–277.39)
      Diabetes (249.6, 250.6)
    • 337.9 Unspecified disorder of autonomic nervous system
  • 354.0: Carpal tunnel syndrome
  • Mononeuropathy:
    • 354.5: Mononeuritis multiplex
    • 354.8: Other mononeuritis of upper limb
    • 354.9: Unspecified mononeuritis of upper limb
    • 355.79: Other mononeuritis of lower limb
    • 355.8: Unspecified mononeuritis of lower limb
    • 355.9: Mononeuritis of unspecified site
  • 357.0: Acute infective polyneuritis (Guillain-Barre syndrome)
  • 357.5: Alcoholic polyneuropathy
  • 358.00: Myasthenia gravis without (acute) exacerbation
  • 358.01: Myasthenia gravis with (acute) exacerbation
  • 359.0: Congenital hereditary muscular dystrophy
  • 359.1: Hereditary progressive muscular dystrophy
  • 359.2x: Myotonic disorders
  • 359.3: Periodic paralysis
  • 359.4: Toxic myopathy
  • 359.5: Myopathy in endocrine diseases classified elsewhere
    Code first underlying disease as:
    Addison’s disease (255.41)
    Cushing’s syndrome (255.0)
    Hypopituitarism (253.2)
    Myxedema (244.0–244.9)
    Thyrotoxicosis (242.0–242.9)
  • 359.6: Symptomatic inflammatory myopathy in diseases classified elsewhere
    Code first underlying disease as:
    Amyloidosis (277.30–277.39)
    Disseminated lupu erythematosus (710.0)
    Malignant neoplasm (140.0–208.9)
    Polyarteritis nodosa (446.0)
    Rheumatoid arthritis (714.0)
    Sarcoidosis (135)
    Scleroderma (710.1)
    Sjogren’s disease (710.2)
  • 359.71: Inclusion body myositis
  • 359.79: Other inflammatory and immune myopathies, NEC
  • 359.8x: Other myopathies
  • 359.9: Unspecified myopathy
  • 710.3: Dermatomyositis
  • 710.4: Polymyositis
  • 721.0: Cervical spondylosis without myelopathy
  • 721.1: Cervical spondylosis with myelopathy

CPT codes for EMGs, nerve conduction tests

Assign the EMG code, which includes the physician’s interpretation of the study, according to the treated body area. Append modifier -59 (Distinct procedural service) when the physician orders more then one test to indicate each was a separate study.

  • 95860: Needle electromyography; one extremity with or without related paraspinal areas
  • 95861: Needle electromyography; two extremities with or without related paraspinal areas
  • 95863: Needle electromyography; three extremities with or without related paraspinal areas
  • 95864: Needle electromyography; four extremities with or without related paraspinal areas
  • 95865: Needle electromyography; larynx
    (Do not report modifier -50 in conjunction with CPT code 95865)
    (For unilateral procedure, report modifier -52 in conjunction with CPT code
    95865)
  • 95866: Needle electromyography; hemidiaphragm
  • 95867: Needle electromyography; cranial nerve supplied muscle(s), unilateral
  • 95868: Needle electromyography; cranial nerve supplied muscle(s), bilateral
  • 95869: Needle electromyography; thoracic paraspinal muscles (excluding T1 or T12)
  • 95870: Needle electromyography; limited study of muscles in one extremity or non-limb (axial) muscles (unilateral or bilateral), other than thoracic paraspinal, cranial nerve supplied muscles, or sphincters

Note the following codes for reporting nerve conduction tests, which physicians often conduct at the same time as EMGs: 

  • 95900: Nerve conduction, amplitude and latency/velocity study, each nerve; motor, without F-wave study
  • 95903: Nerve conduction, amplitude and latency/velocity study, each nerve; motor, with F-wave study
  • 95904: Nerve conduction, amplitude and latency/velocity study, each nerve; sensory

Report CPT codes 95900, 95903, and/or 959904 only once when multiple sites on the same nerve are stimulated or recorded. Coders may not append modifier -51 (Multiple procedures) to these CPT codes.

Editor’s note: Lois E. Mazza, CPC, PCA, is a certified professional coder at Lahey Clinic Medical Center in Burlington, MA. E-mail her at Lois.E.Mazza@lahey.org.



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