Electrodiagnostic medicine

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Electrodiagnosis
MeSH D004568

Electrodiagnosis (EDX) is a method of medical diagnosis that obtains information about diseases by passively recording the electrical activity of body parts (that is, their natural electrophysiology) or by measuring their response to external electrical stimuli (evoked potentials). [1] The most widely used methods of recording spontaneous electrical activity are various forms of electrodiagnostic testing (electrography) such as electrocardiography (ECG), electroencephalography (EEG), and electromyography (EMG). Electrodiagnostic medicine (also EDX) is a medical subspecialty of neurology, clinical neurophysiology, cardiology, and physical medicine and rehabilitation. Electrodiagnostic physicians apply electrophysiologic techniques, including needle electromyography and nerve conduction studies to diagnose, evaluate, and treat people with impairments of the neurologic, neuromuscular, and/or muscular systems. The provision of a quality electrodiagnostic medical evaluation requires extensive scientific knowledge that includes anatomy and physiology of the peripheral nerves and muscles, the physics and biology of the electrical signals generated by muscle and nerve, the instrumentation used to process these signals, and techniques for clinical evaluation of diseases of the peripheral nerves and sensory pathways. [2]

Contents

Training

In the United States, neurologists receive training in performing needle electromyography and nerve conduction studies during a fellowship in clinical neurophysiology or neuromuscular medicine. [3] [4] Physical medicine and rehabilitation physicians receive this training during their residency. [5] and can get further training in a neuromuscular fellowship. The American Board of Electrodiagnostic Medicine certifies US physicians in electrodiagnostic medicine. [6] In Europe, nerve conduction studies and electromyography training may be part of neurology, physical medicine and rehabilitation, or clinical neurophysiology training. In the United States, there is also a certification in neuromuscular medicine. This certification is open only to neurologists and physical medicine and rehabilitation specialists that have completed a fellowship in neuromuscular medicine. The neuromuscular medicine examination includes electrodiagnostic testing as part of the certification examination but also includes broader topics such as genetics, biopsy, and rehabilitation. [7] [8] Technologists sometimes assist in the performance of the NCSs but do not the interpretation. In the United States, the Current Procedural Terminology code of the American Medical Association, states ""Waveforms must be reviewed on site in real time…" In addition, it states that the "Reports must be prepared on site by the examiner, and consists of the work product of the interpretation of numerous test results...along with summarization of clinical and electrodiagnostic data, and physician or other qualified health care professional interpretation. [9]

Patients will typically be referred to a specialist in electrodiagnostic medicine if they have numbness, tingling, pain, weakness or spasms. Common muscle and nerve disorders seen by these type of specialists include pinched nerves in the neck or back (radiculopathy), carpal tunnel syndrome, and neuropathies. More uncommon diseases include ALS, myasthenia gravis, and chronic inflammatory demyelinating polyneuropathy. Using their broader training, physicians in electrodiagnostic medicine, often perform more detailed evaluations which may include laboratory tests, CT or MRI scans, genetic evaluation, biopsy of nerve, skin, or muscle, or perform neuromuscular ultrasound. A more complete listing of disorders and testing can be found under neuromuscular medicine.

Relationship to neurophysiology

Clinical neurophysiology, is a broader field that includes EEG, intraoperative monitoring, nerve conduction studies, EMG and evoked potentials. [10] The American Board of Psychiatry and Neurology provides certification examination in clinical neurophysiology. The American Board of Electrodiagnostic Medicine provides certification in EDX medicines. [11] The American Board of Clinical Neurophysiology certifies in electroencephalography (EEG), Evoked Potentials (EP), Polysomnography (PSG), Epilepsy Monitoring, and Neurologic Intraoperative Monitoring (NIOM). [12] In the US physicians typically specialize in EEG or EDX medicine but not both.

History

Electrodiagnostic medicine traces its origin back to a 1791 experiment by Luigi Galvani. Galvani depolarized frog leg muscles by using metal rods to make contact with the leg muscles. The development of the oscilloscope in 1897 significantly enhanced the ability of scientists to record signals from nerve and muscle. However, it was the needs of those with severe injuries during World War II that created the field of modern electrodiagnostic medicine. In the early 1950s, the first society dedicated to the development of this field, the AAEE, was founded in Chicago by a group of interested specialists in neurology and physical medicine and rehabilitation. James Golseth was instrumental in creating this organization. [13] Over time, newer techniques, such as somatosensory evoked potentials, single fiber electromyography, autonomic testing, and neuromuscular ultrasound have evolved as useful complementary techniques to nerve conduction studies and elecytromyography, which remain the core of electrodiagnostic medicine.

Related Research Articles

In neuroscience, an F wave is one of several motor responses which may follow the direct motor response (M) evoked by electrical stimulation of peripheral motor or mixed nerves. F-waves are the second of two late voltage changes observed after stimulation is applied to the skin surface above the distal region of a nerve, in addition to the H-reflex which is a muscle reaction in response to electrical stimulation of innervating sensory fibers. Traversal of F-waves along the entire length of peripheral nerves between the spinal cord and muscle, allows for assessment of motor nerve conduction between distal stimulation sites in the arm and leg, and related motoneurons (MN's) in the cervical and lumbosacral cord. F-waves are able to assess both afferent and efferent loops of the alpha motor neuron in its entirety. As such, various properties of F-wave motor nerve conduction are analyzed in nerve conduction studies (NCS), and often used to assess polyneuropathies, resulting from states of neuronal demyelination and loss of peripheral axonal integrity.

<span class="mw-page-title-main">Neurology</span> Medical specialty dealing with disorders of the nervous system

Neurology is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the nervous system, which comprises the brain, the spinal cord and the peripheral nerves. Neurological practice relies heavily on the field of neuroscience, the scientific study of the nervous system.

Clinical neurophysiology is a medical specialty that studies the central and peripheral nervous systems through the recording of bioelectrical activity, whether spontaneous or stimulated. It encompasses both research regarding the pathophysiology along with clinical methods used to diagnose diseases involving both central and peripheral nervous systems. Examinations in the clinical neurophysiology field are not limited to tests conducted in a laboratory. It is thought of as an extension of a neurologic consultation. Tests that are conducted are concerned with measuring the electrical functions of the brain, spinal cord, and nerves in the limbs and muscles. It can give the precise definition of site, the type and degree of the lesion, along with revealing the abnormalities that are in question. Due to these abilities, clinical neurophysiology is used to mainly help diagnose diseases rather than treat them.

<span class="mw-page-title-main">Electromyography</span> Electrodiagnostic medicine technique

Electromyography (EMG) is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph to produce a record called an electromyogram. An electromyograph detects the electric potential generated by muscle cells when these cells are electrically or neurologically activated. The signals can be analyzed to detect abnormalities, activation level, or recruitment order, or to analyze the biomechanics of human or animal movement. Needle EMG is an electrodiagnostic medicine technique commonly used by neurologists. Surface EMG is a non-medical procedure used to assess muscle activation by several professionals, including physiotherapists, kinesiologists and biomedical engineers. In computer science, EMG is also used as middleware in gesture recognition towards allowing the input of physical action to a computer as a form of human-computer interaction.

<span class="mw-page-title-main">Physical medicine and rehabilitation</span> Branch of medicine

Physical medicine and rehabilitation, also known as physiatry, is a branch of medicine that aims to enhance and restore functional ability and quality of life to people with physical impairments or disabilities. This can include conditions such as spinal cord injuries, brain injuries, strokes, as well as pain or disability due to muscle, ligament or nerve damage. A physician having completed training in this field may be referred to as a physiatrist.

<span class="mw-page-title-main">Nerve conduction study</span> Diagnostic test for nerve function

A nerve conduction study (NCS) is a medical diagnostic test commonly used to evaluate the function, especially the ability of electrical conduction, of the motor and sensory nerves of the human body. These tests may be performed by medical specialists such as clinical neurophysiologists, physical therapists, physiatrists, and neurologists who subspecialize in electrodiagnostic medicine. In the United States, neurologists and physiatrists receive training in electrodiagnostic medicine as part of residency training and in some cases acquire additional expertise during a fellowship in clinical neurophysiology, electrodiagnostic medicine, or neuromuscular medicine. Outside the US, clinical neurophysiologists learn needle EMG and NCS testing.

<span class="mw-page-title-main">Neuromuscular disease</span> Medical condition

A neuromuscular disease is any disease affecting the peripheral nervous system (PNS), the neuromuscular junctions, or skeletal muscles, all of which are components of the motor unit. Damage to any of these structures can cause muscle atrophy and weakness. Issues with sensation can also occur.

Neuromuscular medicine is a subspecialty of neurology and physiatry that focuses the diagnosis and management of neuromuscular diseases. The field encompasses issues related to both diagnosis and management of these conditions, including rehabilitation interventions to optimize the quality of life of individuals with these conditions. This field encompasses disorders that impact both adults and children and which can be inherited or acquired, typically from an autoimmune disease. A neurologist or physiatrist can diagnose these diseases through a clinical history, examination, and electromyography including nerve conduction studies. Many recent drug therapies have been developed to address the acquired neuromuscular diseases including but not limited to immune suppression and drugs that increase the neurotransmitters at the neuromuscular junction. Gene modifying therapies are also a recent treatment branch of neuromuscular medicine with advancements made in disorders such as spinal muscular atrophy and Duchenne muscular dystrophy. 

<span class="mw-page-title-main">Radiculopathy</span> Medical condition

Radiculopathy, also commonly referred to as pinched nerve, refers to a set of conditions in which one or more nerves are affected and do not work properly. Radiculopathy can result in pain, weakness, altered sensation (paresthesia) or difficulty controlling specific muscles. Pinched nerves arise when surrounding bone or tissue, such as cartilage, muscles or tendons, put pressure on the nerve and disrupt its function.

David Anthony Hilton Yates, FRCP was an English rheumatologist and consultant, president of the British Association for Rheumatology and of the Rheumatology and Rehabilitation Section of the Royal Society of Medicine.

<span class="mw-page-title-main">Hereditary motor and sensory neuropathy</span> Medical condition

Hereditary motor and sensory neuropathies (HMSN) is a name sometimes given to a group of different neuropathies which are all characterized by their impact upon both afferent and efferent neural communication. HMSN are characterised by atypical neural development and degradation of neural tissue. The two common forms of HMSN are either hypertrophic demyelinated nerves or complete atrophy of neural tissue. Hypertrophic condition causes neural stiffness and a demyelination of nerves in the peripheral nervous system, and atrophy causes the breakdown of axons and neural cell bodies. In these disorders, a patient experiences progressive muscle atrophy and sensory neuropathy of the extremities.

<span class="mw-page-title-main">Segun Toyin Dawodu</span> Nigerian physiatrist

Segun Toyin Dawodu is a Nigerian Physiatrist and lawyer with the WellSpan Health, he served as an Associate Professor of Pain Medicine at Albany Medical College.

Clinical Electrophysiological Testing is based on techniques derived from electrophysiology used for the clinical diagnosis of patients. There are many processes that occur in the body which produce electrical signals that can be detected. Depending on the location and the source of these signals, distinct methods and techniques have been developed to properly target them.

Electromyoneurography (EMNG) is the combined use of electromyography and electroneurography This technique allows for the measurement of a peripheral nerve's conduction velocity upon stimulation (electroneurography) alongside electrical recording of muscular activity (electromyography). Their combined use proves to be clinically relevant by allowing for both the source and location of a particular neuromuscular disease to be known, and for more accurate diagnoses.

Charles Francis Bolton, MD, CM, MS, FRCP(C), is a Canadian professor of neurology at Queen's University in Ontario, Canada. He was first to describe critical illness polyneuropathy in a series of patients.

The American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM) is a medical society for the medical subspecialty of neuromuscular and electrodiagnostic medicine based in the United States. Members are primarily neurologists and physiatrists—as well as allied health professionals and PhD researchers.

<span class="mw-page-title-main">Michael Jeffrey Aminoff</span> American clinical neurologist and neurophysiologist

Michael Jeffrey Aminoff is a clinical neurologist and neurophysiologist whose later clinical work focused on treating Parkinson's disease and related movement disorders. He retired in 2022 and lives in San Francisco, California.

Femoral nerve dysfunction, also known as femoral neuropathy, is a rare type of peripheral nervous system disorder that arises from damage to nerves, specifically the femoral nerve. Given the location of the femoral nerve, indications of dysfunction are centered around the lack of mobility and sensation in lower parts of the legs. The causes of such neuropathy can stem from both direct and indirect injuries, pressures and diseases. Physical examinations are usually first carried out, depending on the high severity of the injury. In the cases of patients with hemorrhage, imaging techniques are used before any physical examination. Another diagnostic method, electrodiagnostic studies, are recognized as the gold standard that is used to confirm the injury of the femoral nerve. After diagnosis, different treatment methods are provided to the patients depending upon their symptoms in order to effectively target the underlying causes. Currently, femoral neuropathy is highly underdiagnosed and its precedent medical history is not well documented worldwide.

<span class="mw-page-title-main">Shin Joong Oh</span>

Shin Joong Oh is a Korean physician who is Distinguished Professor of Neurology Emeritus at The University of Alabama at Birmingham in the United States. Oh is a clinician, researcher, and educator known for his contributions to the fields of neurology and electrodiagnostic medicine, particularly electromyography. He retired in 2014.

Zachary London is an American scientist. He is the James W. Albers Collegiate Professor of Neurology at the University of Michigan and program director of the neurology residency at the University of Michigan. He specializes in neuromuscular disease and electromyography. He has been celebrated for his innovative approach to interactive educational tools, and received the American Academy of Neurology A. B. Baker Award for Lifetime Achievement in Neurology Education in 2023.

References

  1. ↑ Electrodiagnosis at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
  2. ↑ Electrodiagnostic Medicine, 2nd edition, Daniel Dumitru, Anthony A. Amato, and Machiel Zwarts; Hanley & Belfus; 2002.
  3. ↑ http://www.acgme.org/acgmeweb/Portals/0/PFAssets/ProgramRequirements/187_clinical_neurophysiology_07012014_1-YR.pdf Archived 2014-12-26 at the Wayback Machine .
  4. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2014-04-18. Retrieved 2015-01-19.{{cite web}}: CS1 maint: archived copy as title (link)
  5. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2014-12-26. Retrieved 2015-01-19.{{cite web}}: CS1 maint: archived copy as title (link)
  6. ↑ "Home | American Board of Electrodiagnostic Medicine".
  7. ↑ "American Board of Physical Medicine and Rehabilitation | an ABMS Member Board".
  8. ↑ "American Board of Psychiatry and Neurology | an ABMS Member Board".
  9. ↑ American Medical Association's (AMA) 2014 Current Procedural Terminology Professional Codebook
  10. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2015-01-20. Retrieved 2015-01-19.{{cite web}}: CS1 maint: archived copy as title (link)
  11. ↑ "Home | American Board of Electrodiagnostic Medicine".
  12. ↑ abcn.org
  13. ↑ Archived at Ghostarchive and the Wayback Machine : "Dr. James Golseth: AANEM's First President". YouTube .

Further reading

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