Electrodiagnostic studies: are they useful in clinical practice?

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.

Impact of electrodiagnostic (EMG/NCS) tests on clinical decision-making and patient perceived benefit in the outpatient physical therapy practice

BACKGROUND

Utilizing Electromyography and Nerve Conduction Study (EMG/NCS) tests, when indicated, may have implications for efficient patient management and assist in more efficient referral to appropriate providers or specialists.

OBJECTIVE

To investigate the impact of Electromyography and Nerve Conduction Studies (EMG/NCS) on clinical decision-making and patient perspectives within PT practice settings.

METHODS

462 patients, who were candidates for diagnostic testing (EMG/NCS) were included in this outcome study and questionnaire-based survey design. Pre-test diagnosis was compared to post-test diagnosis. Post-test, patients were asked to rate their perceived benefit of the testing.

RESULTS

Management was changed in 60.61% of patients post EMG/NCS testing (p < 0.0001). The diagnosis was changed post-EMG/NCS test in 39% of the patients with a change in management, which is greater than expected (p < 0.0004). There was no effect of gender or age (p > 0.05) on change in treatment (tx) or diagnosis (dx). 89.8% of patients agreed, or strongly agreed, that they were better able to understand their condition; 92.4% strongly agreed, or agreed, that they were reassured about their condition; 89.1% strongly agreed, or agreed, that they were better able to manage their condition and 92% reported very high, or high, value perceived from the EMG/NCS test administered.

CONCLUSION

This study demonstrates that EMG/NCS testing appears to have a significant impact on clinical decision-making, and higher scores on the patient perceived benefit.

Utility of electrodiagnostic studies in patients referred with a diagnosis of polyneuropathy

BACKGROUND

Peripheral polyneuropathies (PN) are common neuromuscular conditions. The role of electrodiagnostic study (EDX) in diagnosis of PN is not well-defined.

METHODS

We performed a retrospective chart review of patients referred for EDX evaluation of PN.

RESULTS

Of 162 patients analyzed, 23 had pure peripheral neuropathy (pPN; 14.2%), 29 had peripheral neuropathy and another diagnosis (PN+; 17.9%), 51 had an alternative diagnosis (nonPN; 31.5%), and 59 had normal studies (36.4%). In univariable analysis, age (P < .001) and gender (P = .004) were weakly associated with final diagnosis. In multinomial logistic regression analysis, significant predictors included age (odds ratio [OR] for nonPN/PN+:1.07 per year; 95% confidence interval [CI], 1.03-1.11), gender (OR for PN+:0.2, 95% CI, 0.07-0.61), and diabetes/prediabetes (OR for pPN:3.29; 95% CI, 1.17-9.27).

CONCLUSIONS

These data suggest that EDX commonly yields additional or nonPNs in patients referred with a diagnosis of PN, and although some variables predict electrodiagnosis, none have a large enough effect to suggest poor utility in any subpopulation.

The usefulness of electrodiagnostic consultation in an outpatient clinic

The aim of this study was to record all patients referred to a private outpatient clinic for electrodiagnostic consultation during one calendar year. The demographic data of the patients, the specialty of the referring physicians, the referral diagnosis, the electromyographic (EMG) diagnosis and the concordance of referral and EMG diagnosis among all the referring physician's specialties were recorded. There were one thousand patients (385 men and 615 women). 65.7% of the patients were referred from orthopedists and 22.4% from neurologists. EMG was normal in 498 patients (49.8%). Abnormal in 47.3% of the patients referred by orthopedists and 58.9% of those referred by neurologists. Carpal tunnel syndrome (CTS) was the most frequent electrophysiological diagnosis (26.8%), followed by polyneuropathy (8.9%), radiculopathy (7.1%) and mononeuropathy (4.6%). In this study electrodiagnostic consultation was abnormal in only half of the referred patients. The high proportion of normal EDX tests in this study denotes the need for more accurate clinical diagnosis in order to reduce the time spent and resources. The orthopedist is the initial physician to whom patients with neuromuscular symptoms are seen in the majority of cases. Neurologists seem to be more familiar with neuromuscular symptoms and diseases.

Diagnosis and management of sensory polyneuropathy

Sensory polyneuropathies, which are caused by dysfunction of peripheral sensory nerve fibers, are a heterogeneous group of disorders that range from the common diabetic neuropathy to the rare sensory neuronopathies. The presenting symptoms, acuity, time course, severity, and subsequent morbidity vary and depend on the type of fiber that is affected and the underlying cause. Damage to small thinly myelinated and unmyelinated nerve fibers results in neuropathic pain, whereas damage to large myelinated sensory afferents results in proprioceptive deficits and ataxia. The causes of these disorders are diverse and include metabolic, toxic, infectious, inflammatory, autoimmune, and genetic conditions. Idiopathic sensory polyneuropathies are common although they should be considered a diagnosis of exclusion. The diagnostic evaluation involves electrophysiologic testing including nerve conduction studies, histopathologic analysis of nerve tissue, serum studies, and sometimes autonomic testing and cerebrospinal fluid analysis. The treatment of these diseases depends on the underlying cause and may include immunotherapy, mitigation of risk factors, symptomatic treatment, and gene therapy, such as the recently developed RNA interference and antisense oligonucleotide therapies for transthyretin familial amyloid polyneuropathy. Many of these disorders have no directed treatment, in which case management remains symptomatic and supportive. More research is needed into the underlying pathophysiology of nerve damage in these polyneuropathies to guide advances in treatment.

Electrodiagnostic consultations in Zambia: Referral characteristics and neuromuscular disorders

INTRODUCTION

Research on neuromuscular disorders in sub-Saharan Africa is scarce. We aimed to delineate referral characteristics and the neuromuscular disorders observed among electrodiagnostic (EDX) consultations in a tertiary care setting in Zambia.

METHODS

EDX records were reviewed for all specialist-performed studies after the establishment of the laboratory. The frequency of demographic, medical characteristics, and final EDX impressions are presented.

RESULTS

Among 108 referrals, 52% were male, 84% were adults (mean age 44 years). Referrals were predominantly outpatients (85%) and sent by neurologists (68%). HIV infection was common (12%). Diabetes was rare (3%). Overall, 77% of studies were abnormal. Polyneuropathy was the most common abnormal EDX finding, followed by motor neuron disease.

DISCUSSION

A diverse range of neuromuscular diseases was evaluated among EDX referrals in Zambia. Though labor and expertise intensive, access to EDX consultation can enhance clinical care and facilitate research and surveillance of neuromuscular disorders in the region.

Electrodiagnosis in the Patient with Metabolic Syndrome: Adding Value to Patient Care

Patients with metabolic syndrome are at increased risk of peripheral neuropathy; entrapment neuropathies, such as carpal tunnel syndrome; and spine disease that can lead to radiculopathy or spinal stenosis. Electrodiagnostic studies are a valuable part of patient care in this population. They can confirm suspected diagnoses, uncover additional conditions, and lead to the diagnosis of other causes of neuropathy that require treatment. By assessing the severity of neuropathy, patients at high risk for falls, functional decline, and foot ulcers are identified to guide prevention, treatment, and patient education.

Approach to Peripheral Neuropathy for the Primary Care Clinician

Peripheral neuropathy is commonly encountered in the primary care setting and is associated with significant morbidity, including neuropathic pain, falls, and disability. The clinical presentation of neuropathy is diverse, with possible symptoms including weakness, sensory abnormalities, and autonomic dysfunction. Accordingly, the primary care clinician must be comfortable using the neurologic examination-including the assessment of motor function, multiple sensory modalities, and deep tendon reflexes-to recognize and characterize neuropathy. Although the causes of peripheral neuropathy are numerous and diverse, careful review of the medical and family history coupled with limited, select laboratory testing can often efficiently lead to an etiologic diagnosis. This review offers an approach for evaluating suspected neuropathy in the primary care setting. It will describe the most common causes, suggest an evidence-based workup to aid in diagnosis, and highlight recent evidence that allows for selection of symptomatic treatment of patients with neuropathy.

The usefulness of electrodiagnostic studies in the diagnosis and management of neuromuscular disorders

INTRODUCTION

This study seeks to evaluate the usefulness of electrodiagnostic (EDX) studies in terms of the patient's diagnosis and subsequent management and to identify patient groups in which EDX is particularly useful.

METHODS

The records of new patients referred to a single tertiary hospital EDX laboratory during 1 calendar year were reviewed to determine whether results of EDX studies led to a changed diagnosis and/or management plan. Logistic regression was used to determine whether any factors were associated with changed diagnosis or management.

RESULTS

Results of EDX studies led to a change in diagnosis and a confirmation in diagnosis in 51.5% and 46.5% of the cases, respectively. Results of EDX studies led to a change in the management plan in 63.4% of all cases. The diagnosis and management plan were more likely to be changed in older patients and patients referred in hospital.

DISCUSSION

EDX studies seem useful for confirming or changing the diagnosis and in guiding management in patients with suspected neuromuscular disorders. Muscle Nerve 58: 191-196, 2018.

Requests of electrodiagnostic testing: consistency and agreement of referral diagnosis. What is changed in a primary outpatient EMG lab 16 years later?

The aims are to evaluate electrodiagnostic testing (EDX) requests and verify if presence, consistency and agreement of referral diagnosis could be predicted by patient demographic findings and referring physician typology, and if there were differences in respect to our previous study performed 16 years ago. The study concerns EDX requests referred to two electromyography labs during the year 2011. Differences between findings of general practitioners (GPs) versus specialists' requests and between this study with the previous were assessed. Multivariate logistic regression was performed to calculate odds ratio to assess the strength of association between presence, consistency and agreement of referral diagnosis with patient demographic findings and referring physician typology. We evaluated EDX requests of 1,586 patients (mean age 56 ± 16.7 years, 58.8 % women), 1,050 (66.2 %) were referred by GPs and 536 (33.8 %) by specialists. The suspected diagnosis was reported in 1,033 (65.1 %) requests, the overall consistency was 79.9 % and agreement was 71.9 %. Presence, consistency and agreement of referral diagnosis were predicted by physician's typology (specialist). Only if the suspected diagnosis was carpal tunnel syndrome, consistency and agreement were high regardless of doctor's typology. The physicians, especially GPs, who reported the referral diagnosis decreased during the past 16 years. A diagnostic test, including EDX, should be considered mainly if it fits into the best diagnostic strategy. The neurophysiologist should decide if EDX is useful, make the best decision on further management, and not submit patients to unnecessary and uncomfortable procedures. This choice of behaviour could be questionable and may lead to ethical and deontological problems.

Changes in treatment plan for carpal tunnel syndrome based on electrodiagnostic test results

This study evaluated how often the treatment plan for carpal tunnel syndrome (CTS) changed based on electrodiagnostic test results. Secondly, we assessed factors associated with a change in the treatment plan for CTS. One-hundred-and-thirty English-speaking adult patients underwent electrodiagnostic testing in a prospective cohort study. Treatment plan was recorded before and after testing. Treatment plan changed in 25 patients (19%) based on electrodiagnostic test results. The plan for operative treatment before testing decreased significantly after testing (83% versus 72%). The best logistic regression model for no change in treatment plan included a prolonged or non-recordable median distal sensory latency (normal, prolonged, or non-recordable), and explained 24% of the variation. For surgeons that manage CTS on the basis of objective pathophysiology rather than symptoms, electrodiagnostic test results often lead to changes in recommended treatment.

Utilization of nerve conduction studies for the diagnosis of polyneuropathy in patients with diabetes: a retrospective analysis of a large patient series

BACKGROUND

Diabetic polyneuropathy (DPN) is a disabling complication of diabetes mellitus. A population-based analysis of physician utilization of nerve conduction studies (NCS) for the assessment of DPN was conducted.

METHODS

All electrodiagnostic encounters over a 30-month period using a computer-based neurodiagnostic instrument linked to a data registry were analyzed retrospectively. The DPN case definition was abnormal sural and peroneal nerve conduction.

RESULTS

The study cohort consisted of a total of 63,779 electrodiagnostic encounters performed by 3468 physician practices. Primary care and internal medicine physicians represented 80.1% of the practices and accounted for 65.7% of the encounters. Endocrinologists represented 4.6% of the practices and 20.1% of the encounters. The demographics of patients were 52.7% female; 63.4+/-11.8 (mean+/-standard deviation) years (age); 168.1+/-10.9 cm (height); 92.2+/-22.6 kg (weight); and 32.6+/-7.2 kg/m(2) (body mass index). The most common peroneal abnormality was F-wave latency (33.6%). The sural nerve response latency and amplitude parameters had similar abnormality rates (58.3 and 62.7%). DPN was identified in 52.6% of the encounters; in another 19.3% no neuropathy was found.

CONCLUSIONS

For over 70% of the patients, the specific diagnostic question of the presence of DPN was addressed by NCS with evidence-based criteria. The demographic features were strongly associated with risk of diabetes and DPN, suggesting that NCS were applied to appropriate demographic subgroups. The rate of DPN was also comparable to levels seen by academic electromyography laboratories. In 32.6% of the encounters the NCS suggested a posttest diagnosis other than DPN. This rate was similar to the results of referral to traditional electromyography laboratories. This study demonstrated that NCS using computer-based electrodiagnostic equipment was a suitable tool for the diagnosis of DPN. Furthermore, this technology permits examination of DPN in large populations.

Intérêt et limites de l’électroneuromyogramme pour explorer un membre supérieur douloureux

OBJECTIVE

To study the utility of electroneuromyography in analysis of upper limb pain as a function of the existence of a diagnostic hypothesis.

METHODS

We retrospectively compared the consecutive electroneuromyographic examinations performed between 1 January and 30 September 2004. All recordings were performed by the same examiner in the neurophysiology clinic in the department of neurology of Saint-Etienne university hospital UHC at the request of hospital specialists or surgeon and private general practitioners. In each examination, at a minimum and regardless of the specific situation, motor conduction speed, F waves, and sensory conduction speed were recorded for the median nerve and the ulnar nerve on the right and left. For the arm in question, needle electromyography explored the muscles depending on the C5-T1 roots.

RESULTS

In all, 76 patients had ENMG examinations, 38 for whom the physician had a diagnostic hypothesis and 38 patients without. In the case of a diagnosis based on clinical suspicions, examination was normal in 73.7% of cases compared with 23.7% when there was a clinically based hypothesis (p<0.01). These findings did not vary significantly according to the specialization of the referring physician.

CONCLUSION

Electromyography and nerve conduction studies are useful to confirm a diagnosis based on patient reports and clinical data, it is not useful when no diagnosis has been suggested.

Acquired peripheral neuropathy

The element of time is a crucial factor in the electrodiagnostic presentation of PN. The characteristic changes seen in various neuropathies evolve over time. If testing is performed very early in the course of the disease, abnormalities may not yet be present, in part, because the range of normal values for NCS parameters is broad. In addition, if the process is asymmetric, the affected nerves may not be sampled. Very late in the course of the disease, a multifocal process may appear diffuse and symmetric as the areas of focal involvement coalesce. A primarily, demyelinating process may begin to demonstrate secondary axonal involvement. In very severe neuropathies, it may become difficult to evoke any NCS responses to characterize the neuropathy. It is essential to place the electrodiagnostic findings within the context of the clinical progression to avoid drawing erroneous conclusions. Sometimes, the true nature of the neuropathy is clear only after sequential testing. The etiologic diagnoses of acquired polyneuropathy are vast. A well-crafted electrodiagnostic evaluation can categorize neuropathies into more specific diagnostic groups by identifying the descriptive diagnosis, significantly narrowing the list of possible etiologic diagnoses. Electrodiagnostic testing, which always starts with a pertinent history and physical examination, should always be viewed as a continuation and quantification of the physical examination. Only by knowing the extent and pattern of the clinical involvement is it possible to formulate a thorough electrodiagnostic evaluation. This knowledge is especially important in cases in which the presentation is multifocal, because the neuropathy can be missed entirely if the affected nerves are not evaluated. When evaluating a neuropathy, there are three important questions to answer: (1) Is the process diffuse or multifocal? (2) Is it demyelinating or axonal? (3) Does it predominantly involve the motor or sensory nerves? By assessing the neuropathy along these three axes, the large number of possible etiologic diagnoses becomes much more manageable.