Electrodiagnostic assessment of the autonomic nervous system: A consensus statement endorsed by the American Autonomic Society, American Academy of Neurology, and the International Federation of Clinical Neurophysiology.

Evaluation of disorders of the autonomic nervous system is both an art and a science, calling upon the physician's most astute clinical skills as well as knowledge of autonomic neurology and physiology. Over the last three decades, the development of noninvasive clinical tests that assess the function of autonomic nerves, the validation and standardization of these tests, and the growth of a large body of literature characterizing test results in patients with autonomic disorders have equipped clinical practice further with a valuable set of objective tools to assist diagnosis and prognosis. This review, based on current evidence, outlines an international expert consensus set of recommendations to guide clinical electrodiagnostic autonomic testing. Grading and localization of autonomic deficits incorporates scores from sympathetic cardiovascular adrenergic, parasympathetic cardiovagal, and sudomotor testing, as no single test alone is sufficient to diagnose the degree or distribution of autonomic failure. The composite autonomic severity score (CASS) is a useful score of autonomic failure that is normalized for age and gender. Valid indications for autonomic testing include generalized autonomic failure, regional or selective system syndromes of autonomic impairment, peripheral autonomic neuropathy and ganglionopathy, small fiber neuropathy, orthostatic hypotension, orthostatic intolerance, syncope, neurodegenerative disorders, autonomic hyperactivity, and anhidrosis.

Test Utilization and Value in the Evaluation of Peripheral Neuropathies.

Peripheral neuropathies can be classified as typical or atypical. Patients with atypical neuropathy have one or more of the following features: acute/subacute onset, non-length dependence, motor predominance, or asymmetry. This classification is important because it informs the appropriate diagnostic evaluation of this highly prevalent condition. The evaluation of a typical peripheral neuropathy, also known as distal symmetric polyneuropathy, requires a thorough history, neurologic examination, and focused laboratory testing. Electrodiagnostic testing and MRI account for the majority of costs but rarely lead to changes in diagnosis or management. These costs are increasingly being passed on to patients, especially those with high-deductible health plans. In contrast, patients with atypical neuropathy require more extensive testing, including electrodiagnostic tests. These tests are much more likely to lead to the use of disease-modifying therapies in these patients compared to in those with typical peripheral neuropathy. This article describes two cases to illustrate the appropriate diagnostic workup of those with typical or atypical neuropathy.

The quality of electrodiagnostic tests for carpal tunnel syndrome: Implications for surgery, outcomes, and expenditures.

INTRODUCTION: The quality of electrodiagnostic tests may influence treatment decisions, particularly regarding surgery, affecting health outcomes and health-care expenditures. METHODS: We evaluated test quality among 338 adults with workers' compensation claims for carpal tunnel syndrome. Using simulations, we examined how it influences the appropriateness of surgery. Using regression, we evaluated associations with symptoms and functional limitations (Boston Carpal Tunnel Questionnaire), overall health (12-item Short Form Health Survey version 2), actual receipt of surgery, and expenditures. RESULTS: In simulations, suboptimal quality tests rendered surgery inappropriate for 99 of 309 patients (+32 percentage points). In regression analyses, patients with the highest quality tests had larger declines in symptoms (-0.50 point; 95% confidence interval [CI], -0.89 to -0.12) and functional impairment (-0.42 point; 95% CI, -0.78 to -0.06) than patients with the lowest quality tests. Test quality was not associated with overall health, actual receipt of surgery, or expenditures. DISCUSSION: Test quality is pivotal to determining surgical appropriateness and associated with meaningful differences in symptoms and function.

Assessment of bolus transit with intraluminal impedance measurement in patients with esophageal motility disorders.

BACKGROUND: The clinical management of patients with non-obstructive dysphagia is notoriously difficult. Esophageal impedance measurement can be used to measure esophageal bolus transit without the use of radiation exposure to patients. However, validation of measurement of bolus transit with impedance monitoring has only been performed in healthy subjects with normal motility and not in patients with dysphagia and esophageal motility disorders. The aim was, therefore, to investigate the relationship between transit of swallowed liquid boluses in healthy controls and in patients with dysphagia. METHODS: Twenty healthy volunteers and 20 patients with dysphagia underwent concurrent impedance measurement and videofluoroscopy. Each subject swallowed five liquid barium boluses. The ability of detecting complete or incomplete bolus transit by means of impedance measurement was assessed, using radiographic bolus transit as the gold standard. KEY RESULTS: Impedance monitoring recognized stasis and transit in 80.5% of the events correctly, with 83.9% of bolus transit being recognized and 77.2% of stasis being recognized correctly. In controls 79.8% of all swallows were scored correctly, whereas in patients 81.3% of all swallows were scored correctly. Depending on the contractility pattern, between 77.0% and 94.3% of the swallows were scored correctly. CONCLUSIONS & INFERENCES: Impedance measurement can be used to assess bolus clearance patterns in healthy subjects, but can also be used to reliably assess bolus transit in patients with dysphagia and motility disorders.

Electrodiagnostic consultation and identification of neuromuscular conditions in persons with diabetes.

INTRODUCTION: Although the American Association of Neuromuscular and Electrodiagnostic Medicine recommends that electrodiagnostic procedures should be performed by physicians with specialty training, these procedures are increasingly being performed by non-specialists. METHODS: We used a nationally representative sample of Medicare beneficiaries with diabetes who used electrodiagnostic services in 2006 to examine whether specialists and non-specialists were different in the rates of identifying common neuromuscular conditions. RESULTS: Specialists (neurologists and physiatrists) performed 62% of electrodiagnostic consultations; non-specialist physicians and non-physicians performed 31% and 5%, respectively. After adjusting for age, race/ethnicity, diabetes severity, and comorbidities, specialists were 1.26-9 times more likely than non-physicians to diagnose polyneuropathy, lumbosacral radiculopathy, cervical radiculopathy, carpal tunnel syndrome, and ulnar neuropathy. Almost 80% of electrodiagnostic studies performed by specialists included electromyography testing; fewer than 13% by non-specialists did. CONCLUSIONS: Inadequate use of electromyography and fewer specific diagnoses suggest that many non-specialists perform insufficiently comprehensive electrodiagnostic studies.

Assessment of human body impedance for safety requirements against contact currents for frequencies up to 110 MHz.

This paper deals with contact currents that may occur when the human body is in contact with two electrodes at different electrical potentials, e.g., an electrical/electronic device and the floor. Actually, any device must comply not only with electromagnetic compatibility and safety requirements, but also with specific electromagnetic field exposure recommendations in order to prevent health hazards for the occupational and general public population. Since the contact currents depend on the applied voltage and on the human body impedance, this last parameter has been measured for several configurations in a broadband frequency range, from 40 Hz to 110 MHz. From the measurement results, a new equivalent circuit of the human body impedance is derived by using a vector-fitting procedure. This equivalent circuit is very easy and can be adopted for compliance tests against contact currents.

Current status on electrodiagnostic standards and guidelines in neuromuscular disorders.

The aim of this review is to present the status of electrodiagnostic standards and guidelines in neuromuscular disorders. Electrodiagnostic guidelines are developed on the background of medical technology assessment, wherefore a short presentation of medical technology assessment is given covering: (1) Evidence-based medicine, i.e. "to do the right thing", describing practice parameters and the STARD initiative which introduces evidence-based medicine in electrodiagnostic medicine, (2) Continuous quality improvement, i.e. "to do the thing right", describing variation among laboratories in methods and interpretation of tests, and the need for medical audit and implementation of electrodiagnostic guidelines, (3) Outcome studies, i.e. "is it worthwhile to do the right thing right?". In electrodiagnostic medicine there are very few outcome studies. Standards and guidelines described in the literature for different neuromuscular disorders are presented, often as figures or tables. These cover guidelines developed in detail for CIDP by expert consensus multicentre groups by AAN, INCAT, EFNS/PNS and for other inflammatory demyelinating neuropathies are described, as well as guidelines differentiating between demyelinating pathophysiology and axonal loss by motor and sensory nerve conduction studies. Furthermore, electrodiagnostic guidelines for ALS as detailed in the El Escorial, the modified El Escorial and the recent supplementary Awaji criteria are described and presented in a comprehensive table. Only few electrodiagnostic guidelines are published for nerve entrapment, cervical radiculopathy and neuromuscular transmission failure whereas none are known for myopathy. If no electrodiagnostic criteria for a given disorder exist, criteria for the electrodiagnostic examination are described if present. It is concluded that future research is needed in order to develop more electrodiagnostic guidelines in neuromuscular disorders by international expert consensus groups. Such research should use an evidence-based medicine approach and medical technology assessment and include continuous quality development and outcome studies.

Electrodiagnostic assessment of peripheral neuropathies.

The authors discuss the techniques and use of electrodiagnosis to help fully characterize peripheral neuropathies, including electrodiagnostic principles, normal findings, correlations between underlying nerve pathology that leads to abnormal electrodiagnostic findings, and how to detect and interpret electrodiagnostic findings.

The evidence for intraoperative neurophysiological monitoring in spine surgery: does it make a difference?

OBJECTIVE: The objective of this article was to undertake a systematic review of the literature to determine whether IOM is able to sensitively and specifically detect intraoperative neurologic injury during spine surgery and to assess whether IOM results in improved outcomes for patients during these procedures. SUMMARY AND BACKGROUND DATA: Although relatively uncommon, perioperative neurologic injury, in particular spinal cord injury, is one of the most feared complications of spinal surgery. Intraoperative neuromonitoring (IOM) has been proposed as a method which could reduce perioperative neurologic complications after spine surgery. METHODS: A systematic review of the English language literature was undertaken for articles published between 1990 and March 2009. MEDLINE, EMBASE, and Cochrane Collaborative Library databases were searched, as were the reference lists of published articles examining the use of IOM in spine surgery. Two independent reviewers assessed the level of evidence quality using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria, and disagreements were resolved by consensus. RESULTS: A total of 103 articles were initially screened and 32 ultimately met the predetermined inclusion criteria. We determined that there is a high level of evidence that multimodal IOM is sensitive and specific for detecting intraoperative neurologic injury during spine surgery. There is a low level of evidence that IOM reduces the rate of new or worsened perioperative neurologic deficits. There is very low evidence that an intraoperative response to a neuromonitoring alert reduces the rate of perioperative neurologic deterioration. CONCLUSION: Based on strong evidence that multimodality intraoperative neuromonitoring (MIOM) is sensitive and specific for detecting intraoperative neurologic injury during spine surgery, it is recommended that the use of MIOM be considered in spine surgery where the spinal cord or nerve roots are deemed to be at risk, including procedures involving deformity correction and procedures that require the placement of instrumentation. There is a need to develop evidence-based protocols to deal with intraoperative changes in MIOM and to validate these prospectively.

American Association of Neuromuscular & Electrodiagnostic Medicine evidenced-based review: use of surface electromyography in the diagnosis and study of neuromuscular disorders.

Surface electromyography (sEMG) measures myoelectrical signals recorded from sensors placed on the skin surface. The non-invasive nature of sEMG makes it a potentially useful technology for studying diseases of muscle and nerve. Reviews published by the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) and the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology (AAN), covering 1964-1994 and 1952-1998, respectively, concluded that sEMG adds no clinical utility over conventional needle EMG (nEMG) for the diagnosis of neuromuscular disease. The AANEM sEMG task force reevaluated the diagnostic utility and added value of this technology for the study of neuromuscular disease based on a contemporary review of relevant literature published between January 1994 and February 2006. The present review concludes that sEMG may be useful to detect the presence of neuromuscular disease (level C rating, class III data), but there are insufficient data to support its utility for distinguishing between neuropathic and myopathic conditions or for the diagnosis of specific neuromuscular diseases. sEMG may be useful for additional study of fatigue associated with post-poliomyelitis syndrome and electromechanical function in myotonic dystrophy (level C rating, class III data).

Use of the AAEM guidelines in electrodiagnosis of ulnar neuropathy at the elbow.

OBJECTIVE: The goal of this study was to determine if practice patterns in Washington State were altered by the development and publication of the American Association of Electrodiagnostic Medicine practice parameter for electrodiagnosis of ulnar neuropathy at the elbow. DESIGN: Medical records from 350 workers' compensation patients who underwent surgery for ulnar neuropathy at the elbow in Washington State were reviewed for the consistency of the electrodiagnosticians' report and the practice parameter. Statistical analysis (chi2 or Fischer's exact test) compared prepublication and postpublication patterns of test use. RESULTS: Thirty-one percent of the 153 studies (n = 47) were not consistent with American Association of Electrodiagnostic Medicine guidelines before its publication vs. 34% of the 138 studies (n = 47) after publication. This was not a statistically significant change (P = 0.63). CONCLUSION: Evaluation of the usefulness and dissemination of the guidelines is warranted. The practice parameter may need to be simplified and educational efforts extended to improve provider use of new guidelines.

A new clinical scale of carpal tunnel syndrome: validation of the measurement and clinical-neurophysiological assessment.

OBJECTIVE: To validate a new clinical scale of carpal tunnel syndrome (CTS). The scale is based on clinical history and physical examination findings and includes two figures. The first is a score determined by clinical history and objective findings. The second evaluates the presence/absence of pain as a dichotomous categorical score. METHODS: One hundred and sixty-eight consecutive idiopathic CTS hands were studied in two centers (Rome, Siena). We compare the results of the historical-objective scale (Hi-Ob scale) with the results of other validated measurements of CTS severity: (1) the Italian version of the Boston Carpal Tunnel Questionnaire, (2) the neurophysiological classification adopted by the Italian CTS study group. Furthermore, for the Hi-Ob scale the intra-observer and inter-observer evaluations were assessed. RESULTS: The main Hi-Ob parameter was positively related to the conventional validated measurements. Conversely, the category 'PAIN' of the Hi-Ob scale appeared unrelated to the other clinical and electrophysiological parameters. Intra- and inter-observer evaluation showed the reproducibility of the Hi-Ob assessment. CONCLUSIONS: Our data show that the Hi-Ob scale is a reliable measurement which may be useful in CTS evaluation either for clinical or for scientific purposes.

Clinical evaluation criteria for the assessment of impaired pain sensitivity by thulium-laser evoked potentials.

OBJECTIVES: Cortical potentials evoked by carbon dioxide laser pulses have been applied in clinical practice to study nociceptive pathways for several years. In this study, we evaluate the properties of an infrared laser (thulium-YAG) with a penetration depth in the skin that matches the intracutaneous depth of nociceptors. METHODS: Temperature measurements and modelling showed that the thulium laser generates painful intracutaneous temperatures with less surface heating than the carbon dioxide laser and with no side effects (up to 600 mJ pulse energy). To develop clinical evaluation criteria, laser-evoked potentials (LEPs) were recorded from 3 midline positions (Fz, Cz, Pz) versus linked earlobes in 23 healthy subjects. Within a session, two skin areas were studied twice in a balanced sequence using randomized interstimulus intervals and two intensities in randomized order. RESULTS: After hand and foot stimulation with 540 mJ pulses, all subjects showed reproducible biphasic vertex potential, consisting of a negativity (hand: 210 ms, foot: 250 ms) and a positivity (hand: 330 ms, foot: 380 ms). Mean habituation of the vertex potential amplitude across runs was 25% (hand) or 16% (foot); due to the balanced sequence it did not affect the other comparisons. Following foot stimulation, peak latencies were significantly longer (by 40-50 ms) and amplitudes were significantly smaller than following hand stimulation (22.5+/-6.7 vs. 30.3+/-10.9 microV, mean+/-SD). Using 2. 5 standard deviations from the mean as a cut-off, absolute normative values were determined for peak latencies and amplitudes. In addition, relative normative values were determined for paired comparisons (hand-hand, foot-foot, hand-foot). CONCLUSIONS: The thulium-YAG laser is a useful tool for assessment of impaired pain sensitivity. Representative case reports illustrate that unlike for early SEP components, the most frequent LEP abnormalities were amplitude differences.

Guidelines for ethical behavior relating to clinical practice issues in electrodiagnostic medicine. American Association of Electrodiagnostic Medicine.

In 1993, the American Association of Electrodiagnostic Medicine formed an Ethics and Peer Review Committee in concert with a renewed initiative by organized medicine to emphasize ethical standards. Guidelines for ethical behavior relating to clinical practice issues in electrodiagnostic medicine were developed to formalize the standards of professional behavior for electrodiagnostic medical consultants and were approved by the AAEM Board of Directors in April 1994. The guidelines are modeled after the Code of Professional Conduct of the American Academy of Neurology and are consistent with the Guidelines in Electrodiagnostic Medicine of the American Association of Electrodiagnostic Medicine and Principles of Medical Ethics as adopted by the American Medical Association. The Guidelines may provide grounds for disciplinary action under Article X of the AAEM Bylaws.

Investigative techniques, assessment of incontinence, and urodynamics.

The past year's literature reflects a continued interest in studying and refining standard investigative techniques, both urodynamic and radiographic, that have long been used to evaluate patients with lower urinary tract dysfunction. In addition, new, simple, and inexpensive technologies that allow relatively accurate diagnosis and that minimize medical costs have been introduced. These continued efforts to understand the pathophysiology of the lower urinary tract better bring both the practicing physician and the urogynecologist closer to making correct diagnoses and appropriate therapeutic decisions.