Diagnostic value of different electrophysiologic tests in cervical disk prolapse

A review of electromyography techniques of the cervical paraspinal muscles

Electrodiagnosis for cervical radiculopathy often involves exploration of the cervical paraspinal muscles. Accurate and reproducible results require a technique with specific anatomic localization, direction of insertion, extent of insertion, scoring system for insertion, and criteria for determining abnormality. We sought to understand if a published technique met these criteria. A Medline search found 39 articles with original research and 10 review articles involving the cervical paraspinals. A library search found 19 textbooks since 2000, but 9 were not available. Only two studies were specific to the question. Neither had reproducible techniques and they contradicted each other. Studies in which the paraspinals were used for comparison or inclusion did not provide any specific technique. The review articles and textbooks typically met none of our criteria and the few that discussed technique at all provided no reproducible methods. Despite 80 years of electrodiagnostic testing, there is no useful, reproducible technique for exploring the cervical paraspinal muscles. Yet such a paraspinal mapping technique has proven invaluable in the lumbar region. For cervical electromyography to be of value, the next step is to understand the anatomy and propose a reproducible technique. Subsequent research will determine whether the neck muscles are helpful in the diagnosis of cervical radiculopathy. The absence of a valid reproducible cervical paraspinal technique impedes clinical and scientific understanding of cervical radiculopathy.

2. Cervical radicular pain

INTRODUCTION

Cervical radicular pain is pain perceived in the upper limb, caused by irritation or compression of a cervical spine nerve, the roots of the nerve, or both.

METHODS

The literature on the diagnosis and treatment of cervical radicular pain was retrieved and summarized.

RESULTS

The diagnosis is made by combining elements from the patient's history, physical examination, and supplementary tests. The Spurling and shoulder abduction tests are the two most common examinations used to identify cervical radicular pain. MRI without contrast, CT scanning, and in some cases plain radiography can all be appropriate imaging techniques for nontraumatic cervical radiculopathy. MRI is recommended prior to interventional treatments. Exercise with or without other treatments can be beneficial. There is scant evidence for the use of paracetamol, nonsteroidal anti-inflammatory drugs, and neuropathic pain medications such as gabapentin, pregabalin, tricyclic antidepressants, and anticonvulsants for the treatment of radicular pain. Acute and subacute cervical radicular pain may respond well to epidural corticosteroid administration, preferentially using an interlaminar approach. By contrast, for chronic cervical radicular pain, the efficacy of epidural corticosteroid administration is limited. In these patients, pulsed radiofrequency treatment adjacent to the dorsal root ganglion may be considered.

CONCLUSIONS

There is currently no gold standard for the diagnosis of cervical radicular pain. There is scant evidence for the use of medication. Epidural corticosteroid injection and pulsed radiofrequency adjacent to the dorsal root ganglion may be considered. [Correction added on 12 June 2023, after first online publication: The preceding sentence was corrected.].

Residual one-dimensional convolutional neural network for neuromuscular disorder classification from needle electromyography signals with explainability

BACKGROUND AND OBJECTIVE

Neuromuscular disorders are diseases that damage our ability to control body movements. Needle electromyography (nEMG) is often used to diagnose neuromuscular disorders, which is an electrophysiological test measuring electric signals generated from a muscle using an invasive needle. Characteristics of nEMG signals are manually analyzed by an electromyographer to diagnose the types of neuromuscular disorders, and this process is highly dependent on the subjective experience of the electromyographer. Contemporary computer-aided methods utilized deep learning image classification models to classify nEMG signals which are not optimized for classifying signals. Additionally, model explainability was not addressed which is crucial in medical applications. This study aims to improve prediction accuracy, inference time, and explain model predictions in nEMG neuromuscular disorder classification.

METHODS

This study introduces the nEMGNet, a one-dimensional convolutional neural network with residual connections designed to extract features from raw signals with higher accuracy and faster speed compared to image classification models from previous works. Next, the divide-and-vote (DiVote) algorithm was designed to integrate each subject's heterogeneous nEMG signal data structures and to utilize muscle subtype information for higher accuracy. Finally, feature visualization was used to identify the causality of nEMGNet diagnosis predictions, to ensure that nEMGNet made predictions on valid features, not artifacts.

RESULTS

The proposed method was tested using 376 nEMG signals measured from 57 subjects between June 2015 to July 2020 in Seoul National University Hospital. The results from the three-class classification task demonstrated that nEMGNet's prediction accuracy of nEMG signal segments was 62.35%, and the subject diagnosis prediction accuracy of nEMGNet and the DiVote algorithm was 83.69 %, over 5-fold cross-validation. nEMGNet outperformed all models from previous works on nEMG diagnosis classification, and heuristic analysis of feature visualization results indicate that nEMGNet learned relevant nEMG signal characteristics.

CONCLUSIONS

This study introduced nEMGNet and DiVote algorithm which demonstrated fast and accurate performance in predicting neuromuscular disorders based on nEMG signals. The proposed method may be applied in medicine to support real-time electrophysiologic diagnosis.

Cervical Radiculopathy Focus on Characteristics and Differential Diagnosis

Cervical radiculopathy is characterized by neurological dysfunction caused by compression and inflammation of the spinal nerves or nerve roots of the cervical spine. It mainly presents with neck and arm pain, sensory loss, motor dysfunction, and reflex changes according to the dermatomal distribution. The most common causes of cervical radiculopathy are cervical disc herniation and cervical spondylosis. It is important to find the exact symptomatic segment and distinguish between conditions that may mimic certain cervical radicular compression syndromes through meticulous physical examinations and precise reading of radiographs. Non-surgical treatments are recommended as an initial management. Surgery is applicable to patients with intractable or persistent pain despite sufficient conservative management or with severe or progressive neurological deficits. Cervical radiculopathy is treated surgically by anterior and/or posterior approaches. The appropriate choice of surgical treatment should be individualized, considering the patient’s main pathophysiology, specific clinical symptoms and radiographic findings thoroughly.

Evaluation of persons with suspected lumbosacral and cervical radiculopathy: Electrodiagnostic assessment and implications for treatment and outcomes (Part I)

Persons with back, neck, and limb symptoms constitute a major referral population to specialists in electrodiagnostic (EDX) medicine. The evaluation of these patients involves consideration of both the common and less common disorders. The EDX examination with needle electromyography (EMG) is the most important means of testing for radiculopathy. This test has modest sensitivity but high specificity and well complements imaging of the spine. Needle EMG in combination with nerve conduction testing is valuable in excluding entrapment neuropathies and polyneuropathy-conditions that frequently mimic radicular symptoms. In this first of a two-part review, the optimal EDX evaluation of persons with suspected radiculopathy is presented. In part two, the implications of EDX findings for diagnosis and clinical management of persons with radiculopathy are reviewed.

Motor Evoked Potentials after Supraspinal Stimulation in Pre- and Postoperative Evaluations of Patients with Cervical Radiculopathy

Objective

Pre- and postoperative comparative evaluation of neurophysiological tests and clinical trials. Analysis of the diagnostic value of motor evoked potentials (MEP) induced by a magnetic field after supraspinal stimulation. Evaluation of the sensitivity and specificity of electromyography (EMG) and MEP is achieved.

Methods

EMG, ENG, M-wave, F-wave, and MEP tests were performed on 35 patients with confirmed cervical radiculopathy in pre- and postoperative evaluations. The clinical trial consisted of evaluation of muscle strength, a sensory perception test and evaluation of tendon reflexes and pain severity.

Results

The sensitivity of the resting EMG and MEP tests is 24%-67% and 6%-27%, while their specificity is 43%-80% and 86%-100%, respectively. The postoperative evaluation revealed a statistically significant reduction in pain severity (p=0001), an increase in muscle strength in DP (p=0.0431), BB (p=0,0431), and TB (p=0.0272), and improvement of touch sensation in terms of dermatomal innervation in C5 (p=0.0001) and C6 (p=0.0044).

Conclusions

Tests comparing MRI sensitivity to neurophysiological tests show that neuroimaging is more sensitive in diagnostics of patients with cervical radiculopathy; however, clinical neurophysiology tests are more specific in reference to clinical trials.

Critically re-evaluating a common technique: Accuracy, reliability, and confirmation bias of EMG

OBJECTIVES

(1) To assess the diagnostic accuracy of EMG in radiculopathy. (2) To evaluate the intrarater reliability and interrater reliability of EMG in radiculopathy. (3) To assess the presence of confirmation bias in EMG.

METHODS

Three experienced academic electromyographers interpreted 3 compact discs with 20 EMG videos (10 normal, 10 radiculopathy) in a blinded, standardized fashion without information regarding the nature of the study. The EMGs were interpreted 3 times (discs A, B, C) 1 month apart. Clinical information was provided only with disc C. Intrarater reliability was calculated by comparing interpretations in discs A and B, interrater reliability by comparing interpretation between reviewers. Confirmation bias was estimated by the difference in correct interpretations when clinical information was provided.

RESULTS

Sensitivity was similar to previous reports (77%, confidence interval [CI] 63%-90%); specificity was 71%, CI 56%-85%. Intrarater reliability was good (κ 0.61, 95% CI 0.41-0.81); interrater reliability was lower (κ 0.53, CI 0.35-0.71). There was no substantial confirmation bias when clinical information was provided (absolute difference in correct responses 2.2%, CI -13.3% to 17.7%); the study lacked precision to exclude moderate confirmation bias.

CONCLUSIONS

This study supports that (1) serial EMG studies should be performed by the same electromyographer since intrarater reliability is better than interrater reliability; (2) knowledge of clinical information does not bias EMG interpretation substantially; (3) EMG has moderate diagnostic accuracy for radiculopathy with modest specificity and electromyographers should exercise caution interpreting mild abnormalities.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that EMG has moderate diagnostic accuracy and specificity for radiculopathy.

A comparison of magnetic resonance imaging with electrodiagnostic findings in the evaluation of clinical radiculopathy: a cross-sectional study

PURPOSE

The aim of this study was to evaluate the agreement of magnetic resonance imaging and electrodiagnostic studies by comparing their findings in patients with clinically suspected radiculopathy. The agreements between these two procedures and clinical findings were also examined.

METHODS

In a 2-year cross-sectional study, a total of 114 patients with clinically suspected cervical or lumbosacral radiculopathy were included.

RESULTS

The total agreements between clinical with MRI and EDX findings were 72 and 52%, respectively while their agreements were similar in group definite (89 vs. 82%). The agreement between EDX and MRI was 59.6 in total and 49% with respect to clinical findings.

CONCLUSION

This study further supports that these two methods are complementary in general. It is reasonable to add EDX when there is discrepancy between MRI and clinical findings or when MRI neurologic findings are not visible.

Electrical impedance myography in the diagnosis of radiculopathy

INTRODUCTION

We sought to determine whether electrical impedance myography (EIM) could serve as a diagnostic procedure for evaluation of radiculopathy.

METHODS

Twenty-seven patients with clinically and radiologically diagnosed cervical or lumbosacral radiculopathy who met a "gold standard" definition underwent EIM and standard needle electromyography (EMG) of multiple upper or lower extremity muscles.

RESULTS

EIM reactance values revealed consistent reductions in the radiculopathy-affected myotomal muscles as compared with those on the unaffected side; the degree of asymmetry was associated strongly with the degree of EMG abnormality (P < 0.001). EIM had a sensitivity of 64.5% and a specificity of 77.0%; in comparison, EMG had a sensitivity of 79.7% but a specificity of 69.7%.

CONCLUSIONS

These findings support the potential for EIM to serve as a new non-invasive tool to assist in diagnosis of radiculopathy; however, further refinement of the technique is needed for this specific application.

Evaluating the patient with suspected radiculopathy

Persons with back, neck, and limb symptoms are commonly seen by health care providers. They constitute a major referral population to specialists in electrodiagnostic medicine. The evaluation of these patients involves consideration of both the common and less common disorders. The electrodiagnostic examination with needle electromyography is the most important means of testing for radiculopathy. This test has modest sensitivity but high specificity. It complements imaging of the spine. Electromyography in combination with nerve conduction testing is valuable in excluding entrapment neuropathies and polyneuropathy, conditions that frequently mimic radicular symptoms. A streamlined examination with 6 muscles, 1 of which is the paraspinal, has a high diagnostic yield, yet minimizes patient discomfort and examiner time. This article presents an overview of the electrodiagnostic evaluation for patients with suspected radiculopathy.

Whiplash injury: is there a role for electromyographic studies?

INTRODUCTION

This retrospective study was undertaken to assess the value of carrying out baseline and follow-up electromyography (EMG) for patients with whiplash-associated disorders (WAD, grades I and II) after they had undergone rear-end car collisions, and to determine if there is any agreement with clinical and imaging (CT and MRI) findings.

MATERIALS AND METHODS

We carried out a retrospective review of 330 patients seeking compensation after rear-end car collisions. The treating physician referred all patients for EMG studies in the post-injury follow-up period and for additional CT scans and MRIs. All patients underwent physical and X-ray examination by the senior author (SD), and 75 patients with persistent radicular complaints were referred again for EMG studies. The results of the association between patient complaints, clinical examination, and EMG, CT and MRI studies are reported.

RESULTS

We sought but failed to find any correlations between 354 EMG results with those of 278 CT scans and 75 MRIs. Both subjective complaints and early vs late EMG abnormalities showed statistical agreement and persistency of findings only at disc level C7/D1.

CONCLUSIONS

Our data indicate that follow-up EMG studies for patients with WAD do not contribute any useful information for patient management.

Electrodiagnosis of neck pain

The past 3 decades have witnessed tremendous advances in the field of electrodiagnostic medicine. The high-performance electronics and microprocessors available in contemporary electrodiagnostic instruments have improved the ability to detect, record, measure, and interpret the action potentials arising from the nerves and muscle fibers. With their increased ease of use and effectiveness in both diagnosis and prognosis, electrodiagnostic tests have become valuable tools in evaluation of patients with neck pain. As with any laboratory measure, the utility of electrodiagnostic testing can be increased when it is used in appropriate clinical contexts and when its limitations are understood.

Electrodiagnostic approach to patients with suspected radiculopathy

This article reviews the electrodiagnostic testing for persons suspected of having radiculopathies and the expected sensitivities that different testing modalities provide. One cannot minimize the importance of the clinical evaluation and differential diagnosis formulation by the electrodiagnostician to guide testing. The needle EMG examination is the most useful electrodiagnostic test but is limited in sensitivity. Electromyographic screening examinations using six muscles are possible that optimize identification yet minimize patient discomfort. Electrodiagnostic findings must be interpreted relative to the patient's clinical presentation, and the consultant should tailor the electrodiagnostic study to the clinical situation.

Diagnostic selective nerve root blocks: indications and usefulness

Diagnostic SNRIs are a useful tool in the diagnosis of radicular pain in atypical presentations. Diagnostic SNRI is indicated in the following circumstances: (1) for atypical extremity pain; (2) when imaging studies and clinical presentation do not correlate; (3) when electromyography and MRI are not corroborative or are equivocal; (4) for anomalous innervations, such [figure: see text] as conjoint nerve roots or furcal nerves [71]; (5) for failed back surgery syndrome with atypical extremity pain; and (6) for transitional vertebrae. Patients should have demonstrated a failure to improve with less invasive treatment. In these patients, a diagnostic SNRI may localize the pain to a specific spinal nerve. It must be emphasized that the diagnostic SNRI only determines if pain is emanating from a specific nerve root or spinal nerve. A diagnostic SNRI does not determine what has caused the nerve root or spinal nerve pain, nor does it provide prognostic information. The etiology of the nerve root pain, mechanism of injury, underlying anatomy, duration of symptoms, comorbidities, patient desire, physician skill, and a host of other factors determine the appropriate treatment and prognosis.

Diagnosis and nonoperative management of cervical radiculopathy

STUDY DESIGN

Qualitative, comprehensive literature review.

OBJECTIVE

To discuss and summarize the current peer-reviewed literature related to the management of patients with cervical radiculopathy.

BACKGROUND

Cervical radiculopathy is a lesion of the cervical spinal nerve root with a reported prevalence of 3.3 cases per 1000 people; peak annual incidence is 2.1 cases per 1000 and occurs in the fourth and fifth decades of life. Nerve root injury has the potential to produce significant functional limitations and disability.

METHODS AND MEASURES

A search of the MEDLINE, CINAHL, and Web of Science databases for the periods 1966, 1982, and 1996, respectively, to December 1999 was conducted using selected keywords and MeSH headings. The bibliography of all retrieved articles were searched and pertinent articles were obtained. The Cochrane Database of Systematic Reviews was also searched. Literature related to the diagnosis, prognosis, and treatment of cervical radiculopathy were thoroughly reviewed and summarized using a critical appraisal approach.

RESULTS

Although cervical radiculopathy remains largely a clinical diagnosis, the true diagnostic accuracy of the clinical examination for cervical radiculopathy is unknown. Imaging and electrophysiologic tests are capable of detecting clinically significant problems in many patients and each modality has inherent strengths and weaknesses; technical as well as practical factors affect the choice of procedure. The natural course of cervical radiculopathy appears to be generally favorable but no prognostic or risk factors have been firmly established and the efficacy of various nonoperative treatments for the condition is unknown.

CONCLUSION

A clear definition of terms and further research are required to establish definitive diagnostic criteria and effective treatment for the management of patients with cervical radiculopathy.

Electromyography and magnetic resonance imaging in the evaluation of radiculopathy

Electromyography (EMG) and magnetic resonance imaging (MRI) are commonly used in the diagnosis of cervical and lumbosacral radiculopathy, but the agreement between the two studies is unknown. We retrospectively studied 47 patients with a clinical history compatible with either cervical or lumbosacral radiculopathy who were evaluated with both an EMG and a spine MRI within 2 months of each other. Among these patients, 55% had an EMG abnormality and 57% had an MRI abnormality that correlated with the clinically estimated level of radiculopathy. The two studies agreed in a majority (60%) of patients, with both normal in 11 and both abnormal in 17; however, only one study was abnormal in a significant minority (40%), suggesting that the two studies remain complementary diagnostic modalities. The agreement was higher in patients with abnormal findings on neurologic examination, underscoring the difficulty of confirming the diagnosis in mild radiculopathy.

The diagnosis and treatment of cervical radiculopathy

To provide a comprehensive review of the presentation, evaluation, differential diagnosis, treatment and return-to-play criteria which can be useful to the clinician caring for athletes with cervical radiculopathy. A review of the literature on cervical radiculopathy and sports injuries of the cervical spine was performed. This information was used in conjunction with the author's clinical experience to present a literature based approach to the diagnosis and treatment of cervical radiculopathy in athletic individuals. There was limited scientific literature on the evaluation and treatment of cervical radiculopathy in athletes. Many studies reported on the evaluation and treatment of the "burner" or "stinger" in the younger athlete which may represent a cervical radiculopathy in many of these cases. A nonoperative treatment plan using a logical step-wise approach is successful in the vast majority of these patients. Using the history and a detailed physical examination, along with imaging and other diagnostic studies when necessary, a proper diagnosis of cervical radiculopathy can be made. Once a discrete diagnosis is made, then a systematic approach to the treatment and rehabilitation can be implemented to optimize a safe return to competition.

EMG before and after cervical anterior discectomy

INTRODUCTION

In patients with cervical root syndromes, the relation between clinical findings and EMG results, the value of the registration of the H-reflex latency of the flexor carpi radial muscle (HFCR) and the rate of recovery of EMG abnormalities following surgery are unclear.

METHODS

In 68 patients with cervical radicular syndromes caused by intervertebral disc lesions, EMG was made shortly before anterior cervical discectomy and four months later. EMG consisted of needle myography and bilateral determination of the HFCR.

RESULTS

Results of HFCR were unrelated to findings on needle myography. Preoperative EMG abnormalities were related to more severe clinical and myelographic findings. A preoperative abnormal HFCR correlated with good clinical outcome. No relation was found between the clinical outcome and EMG-findings during follow-up.

CONCLUSION

Determination of HFCR is a useful EMG-test, but further comparison to tendon reflexes is necessary. EMG identifies patients with more severe root lesions, but cannot be used for evaluation of persistent complaints within the first half year following surgery.

Cervical radiculopathy

The history, pathoanatomy and pathophysiology, clinical picture, differential diagnosis, diagnostic evaluation, and treatment of cervical radiculopathy are reviewed. The review is based on a 10-year Medline literature search, review of bibliographies in textbooks, and bibliographies in articles obtained through the search. Cervical radiculopathy, although recognized early in the 20th century, was first associated with disc pathology in the mid-1930s. It is most commonly caused by disc herniation or cervical spondylosis. History and physical examination using pain location, manual muscle testing, and specialized testing (Spurling's maneuver) will usually suffice to diagnose the radiculopathy and determine the root level involved. Diagnostic imaging such as magnetic resonance imaging, computed tomography, or myelography should be used as presurgical evaluative tools or when tumor or other etiology besides disc herniation or spondylosis is suspected. Electromyography is of benefit in distinguishing various entities that clinically present similar to cervical radiculopathy and can also help to "date" the lesion. Treatment of this disorder has not been systematically studied in a controlled fashion. However, using a variety of different treatments, the radiculopathy usually improves without the need for surgery. Indications for surgery are unremitting pain despite a full trial of non-surgical management, progressive weakness, or new or progressive cervical myelopathy. Prospective studies evaluating the various treatment options would be of great benefit in guiding practitioners toward optimum cost-effective evaluation and care of the patient with cervical radiculopathy.

Dermatomal somatosensory evoked potentials: cervical, thoracic, and lumbosacral levels

Somatosensory evoked potentials were recorded at the scalp to stimulation of the skin at C4, C5, C6, C7, C8, T2, T4, T6, T8, T10, T12, L2, L3, L4, L5, and S1 dermatomes and of the tibial nerve. Stimulation and recording techniques are described. Data were obtained from 41 normal subjects, 25 of which had all 16 dermatomes studied. Wave form descriptions include both typical and atypical presentations. Descriptive statistics for latency, amplitude, left to right comparisons, and level to level comparisons are given. Scalp response latencies for distal extremity dermatomes were well correlated with height but not with vertebral column length, whereas latencies for thoracic dermatomes were not well correlated with either height or vertebral column length. Since scalp response amplitude data were not normally distributed, they were logarithmically transformed and minimum and maximum limits for 1 S.D., 2 S.D., and 3 S.D. derived. Left/right amplitude ratios were similarly treated. Level to level comparisons were achieved with a Z score concordance analysis, which showed that the response values at one level can be used to predict the response values at another level.

Somatosensory evoked potentials from cervical and lumbosacral dermatomes

A method for recording the somatosensory evoked potentials after stimulation of the cervical and lumbosacral dermatomes is described. Normative values and their ranges are given for each dermatome including left-right differences. A significant correlation was found between latencies and conduction distance. Dermatomal SEPs may play a role in diagnosing cervical and lumbosacral radiculopathies.

Clinical and electrodiagnostic findings, nerve biopsy and blood group markers in a family with hereditary neuropathy with liability to pressure palsies

Clinical, electrophysiologic and biopsy findings as well as studies of blood group markers in a family with hereditary neuropathy with liability to pressure palsies (HNPP) are reported. There was an autosomal dominant trait without genetic linkage between the HNPP gene and blood group markers controlled by chromosome 1. Reduced motor and sensory nerve conduction velocity was found in clinically affected and unaffected nerves. Characteristic morphological changes in sural nerve biopsy including tomaculous swelling were present.