State of the Art Review
Physical Medicine & Rehabilitation
Evaluation of Radiculopathy:
How Useful is Electrodiagnostic Testing?
This State-Of-The-Art-Review is cited several times annually in the medical literature and by insurance companies. In 2015 neurologists presented this review to the Georgia Medical Board in support of the efficacy of EMG-Type EDX, so it is as relevant today as when first published in 1999. We doubt it is ever read, because to anyone actually reading it would realize the stark limitations of standard EMG-Type EDX in diagnosing radiculopathy.
Quotes are in bold font. Underlining is our emphasis. Our explanations are in plain font and preceded by*.
Pg. 251-252: “In chronic cases, particularly in individuals with predominantly sensory symptoms (*pain), it is difficult or impossible to clinically estimate the type or severity of nerve injury. (*When the large fibers EMG tests assess are involved) Only if there is obvious muscle atrophy can one know that motor axon degeneration has occurred. The electrodiagnostic study (EMG) can be normal in the face of known pathology.”
Pg. 254: (*Concerning H-wave (Hoffman 1918) “Potentially useful . . . However, the only H response used with any regularity is in the assessment of S1 fibers. . . Many argue H reflex is simply a neurophysiologic ankle stretch reflex, therefore, does not have added value in the evaluation of radiculopathy.”
Pg. 255: (*F-wave – Foot Reflex) “Despite the theoretical advantage of using the F wave response to determine proximal conduction, it is of little practical application in the evaluation of radiculopathy, especially a lesion at a single level. Severe root damage at multiple levels is necessary to prolong the latency. The abnormalities of F waves do not correlate with either needle examination or clinical findings.
Pg. 258: “Most reports on EDX sensitivity used surgical confirmation as the gold standard although some did use imaging (CT-scan & MRI). The specificity of imaging is low, with up to 50% of asymptomatic subjects having an anatomical abnormality noted on random screening. Imaging is therefore not ideal as a gold standard for evaluation of electrodiagnostic testing. Additionally, using surgery as a gold standard will skew the population tested because there is a selection bias toward those subjects who have their radiculopathy treated surgically, typically the most severe cases. No study has been reported where all subjects underwent EMG and an operation based on initial presentation alone.” “If only sensory fibers are involved or if the motor involvement is mild, the sensitivity of a standard EMG is reduced; the EMG will be normal while the person actually has a radiculopathy. The sensitivity is also reduced in a slowly progressive lesion and when the examination is performed late in the course (3-6 months) of a mild to moderate, acute compressive lesion.”
Pg. 258: “Thus, sensitivities reported in the literature are falsely elevated and tend to lull us into thinking that electrodiagnostic evaluation of radiculopathy is both sensitive and specific. However, even using the sensitivity reported in the current literature, 15-50% of electrodiagnostic studies evaluating possible radiculopathy that are reported as normal may have a compressive radiculopathy that we are not able to detect. The actual percentage of negatives may be even higher if we account for the biases used in our selection of a gold standard for compressive radiculopathy.”
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Massachusetts Gen. Hospital Handbook of Pain Management, 2nd Ed. (2002
Pg. 382: “In most cases of neck and back pain the anatomic and physiologic diagnosis remains unclear.” Note: “most case” (*is over 50%).
P. 380: “History and physical examination have a limited role in the diagnosis of back and neck pain, but are important in ruling out serious pathology. The etiology of pain in a significant number of patients with back and neck pain may remain unknown. Nonspecific back or neck pain is a legitimate diagnosis.”
Pg. 353: “Most neuropathic pain syndromes are mediated by small-diameter C fibers, which are not evaluated by these tests (EMG) so their value in the evaluation of neuropathic pain syndromes is limited. It is important to note that the sensory nerve action potentials (SNAP) can be normal in patients with neuropathic pain syndromes of radicular origin, because the causative lesion is proximal to the dorsal nerve root ganglion.”
DeJong’s: The Neurological Examination
*This text is universally considered the “Neurodiagnosis Bible.” In 844 pages less than 50 words concern EMG, explains how EDX is used in muscle atrophy and fairly rare spinal cord motor lesions. Also explained is the limitations due to more than one adjacent motor nerve root must be grossly damaged before diagnosing low back radiculopathy.
The Spine, 5th Ed. (Saunders) 2006
Pg. 218: “Whenever a patient, whose sole complaint is pain (affecting the limbs, neck or back), is referred for an EDX (EMG-type) examination, there is the expectation that there has been some concomitant damage to large nerve fibers. As is noted later, with chronic lesions, this is usually an unrealized hope.”
Neurology for the Non-Neurologist - Wiener & Goetz - Lippinott (2002)
Pg. 23: “EMG and NCV in neck, shoulder and back pain, in the absence of motor deficit, is costly, time consuming and seldom benefits the patient.”
EMG Experts Help Insurers Deny Coverage
*In the 1980s insurers called CT Scans “a billing gimmick.” Because insurers do not have Cost Benefit Departments, they do not evaluate new technology to see if it could help patients or save money. This is the case with the Axon-II. It can be quickly mastered by non-neurologists and offers a painless, less expensive and far more accurate method of diagnosing radiculopathy, but EMG providers cooperate with insurers to kill use of the Axon-II.
Below are statement made in a report by an EDX experts who is a past president of the AANEM. Lacking spf-NCS certification he clearly shows a limited understanding of sensory physiology.
EDX report excerpts are in bold font. *Explanations are in plane font preceded by an *.
Dr. T: Report for Allstate Insurance
*Upon becoming AANEM president Dr. T made this statement; “The field of medicine is in a state of flux, and the AANEM has always done an admirable job in educating and advocating for its members so that they can better adapt to these changes.”
*One can substitute the word “threats to our practices” for “changes.”
Dr. T:
After careful review and analysis of the information provided above, I have concluded that the Axon-II is NOT capable of selectively stimulating and recording A-delta fast pain sensory nerve fibers. If you did activate the A-delta (Fast Pain) fibers the patient would only feel pain and pull away from the stimulus (withdrawal reflex).
*On the same page, next to Dr. T statement is a chart from Guyton & Hall Textbook of Medical Physiology that clearly shows A-delta fibers transmit many sensations other than pain.
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skin hairs receptors sensations
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deep pressure
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light touch
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hot
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cold
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stretch
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pricking pain
Dr. T:
Cites to quotes from Segen’s Medical Dictionary
1. First Pain (redirected from Epicritic Pain) One of 2 components of acute pain over the skin surface, which is A-delta fiber mediated and characterized as a sharp, pricking, well localized sensation.
2. Physiology pain: fast pain is a protective and useful response, enabling the individual to accurately localize and withdraw from the pain stimulus, to avoid or reduce tissue damage; caused by stimulation of high-threshold thermo/mechanical nociceptors, and transmitted along fast-conduction A-delta fibers.
*Dr. T fails to consider the salient points that we underline above. A weak stimulus, such as produced by picking up a cool drinking glass, does NOT activate High-Threshold Thermo/Mechanical Receptors, yet A-delta fibers also carry these mild signals.
*High-Threshold Receptor Activation
A strong stimulus is required to activate High-Threshold Thermo/Mechanical skin receptors, which in turn excite a sufficient number of A-delta fibers to cause reflex withdrawal. Reflex withdrawal is initiated when large numbers of A-delta fibers synapse with spinal cord motor neurons, activating muscle contractions that pull us away from a potentially damaging contact.
