Identification of cervical radiculopathies: optimizing the electromyographic screen

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.].

Electrodiagnostic Assessment of Radiculopathies

This article discusses the electrodiagnostic assessment of radiculopathy. Relevant anatomy initially is reviewed followed by discussion surrounding the approach to nerve conduction studies and needle electrode examination when it comes to radiculopathy evaluation. Pitfalls of the electrodiagnosis versus clinical diagnosis of radiculopathy and the definitions of acute versus chronic, and active versus inactive, are reviewed.

Interpretation of Electrodiagnostic Studies: How to Apply It to the Practice of Orthopaedic Surgery

Electrodiagnostic studies may help orthopaedic surgeons to identify and confirm nerve pathology, determine severity of disease, localize the lesion, identify concomitant or alternative pathology, and prognosticate potential outcomes with nonoperative or operative treatment. Surgeons should recognize the indications for electrodiagnostic studies, principles of their performance, and how to assess the primary data generated by the examination and how it can inform their treatment plans.

Direct Involvement of Concomitant Foraminotomy for Radiculomyelopathy in Postoperative Upper Limb Palsy in Cervical Laminoplasty

OBJECTIVE

Although concomitant foraminotomy has been reported to increase the risk of postoperative upper limb palsy (ULP) in cervical laminoplasty, the specific effects of concomitant foraminotomy on ULP remain uncertain. This study aimed to clarify the effect of concomitant foraminotomy on ULP in cervical laminoplasty.

METHODS

We identified 19 patients who developed ULP after laminoplasty with concomitant foraminotomy for radiculomyelopathy with nerve root impingement (laminoplasty with concomitant foraminotomy group [F-group]) from 4080 patients who underwent primary cervical laminoplasty at 27 affiliated institutions between 2012 and 2018. An age- and sex-matched control group comprised patients who developed ULP after laminoplasty without concomitant foraminotomy (n = 76, 4:1 ratio with F-group). Collected data included the time of onset and distribution of ULP (side and level). The site of foraminotomy was recorded in the F-group.

RESULTS

The F-group showed a significantly higher incidence of ULP than the candidates for the control group (15.1% vs. 3.1%, P < 0.001). The site of foraminotomy was consistent with the distribution of ULP in 79% (15 of 19 patients) of the F-group. The F-group showed a significantly higher proportion of preoperative upper-limb muscle weakness (74% vs. 37%, P = 0.005) and early-onset ULP occurring by postoperative day 1 (63% vs. 33%, P = 0.02) compared with the control group.

CONCLUSIONS

Our results indicate that the foraminotomy procedure in the stenotic foramen is directly involved in ULP. Combined with a previous report suggesting that early-onset ULP is associated with thermal nerve damage, our results indicate that thermal nerve damage partly explains the increased incidence of ULP in the F-group.

Spurling's test - inconsistencies in clinical practice

Objective: The purpose of this study was to investigate the methodology, interpretation, and perceived value of Spurling's test toward diagnosis/classification and treatment. Methods: An anonymous web-based survey was made available to physical therapist members of the Academy of Orthopaedic Physical Therapy of the American Physical Therapy Association. Based on video demonstrations of technique and symptom distribution, questions included preferred method, criteria for test interpretation, and perceived value of Spurling's test and other examination findings toward clinical decision-making. Professional profile data were also collected. Results: Among the 452 participants completing the survey, no method of testing was preferred by more than 37%, with ipsilateral lateral flexion, rotation, and extension with compression being most frequently preferred followed by ipsilateral lateral flexion with compression at 32%. Proximal provocation of symptoms only without distal symptoms was interpreted as a positive test by 67%. Participants rated Spurling's test of moderate to low value toward diagnosis/classification and treatment. Discussion: Inconsistency with methodology and interpretation of Spurling's test is suggested to be pervasive in physical therapist practice. While an optimal test methodology has yet to be identified, result interpretation does have a basis for clarification toward diagnosis/classification and reduction of unwanted variance in practice.

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.

Neck Pain and Lower Back Pain

Neck pain is the fourth leading cause of disability. Acute neck pain largely resolves within 2 months. History and physical examination play a key role in ruling out some of the more serious causes for neck pain. The evidence for pharmacologic interventions for acute and chronic musculoskeletal neck pain is limited. Lower back pain is the leading cause of disability and productivity loss. Consultation with a physical medicine and rehabilitation spine specialist within 48 hours for acute pain and within 10 days for all patients with lower back pain may significantly decrease rate of surgical interventions and increase patient satisfaction.

Motor amplitudes may predict electromyography-confirmed radiculopathy in patients referred for radiating limb pain

INTRODUCTION

Radiculopathy is diagnosed by needle electromyography, with nerve conduction studies excluding alternative diagnoses.

METHODS

In patients referred for electrodiagnostic evaluation of radiating limb pain, we compared ulnar motor amplitudes between those with and without electromyographically confirmed C8 radiculopathy, as well as fibular motor amplitudes between those with and without electromyographically confirmed L5 radiculopathy.

RESULTS

Patients with electromyographically confirmed C8 or L5 radiculopathy demonstrated decreased ulnar or fibular motor amplitudes, respectively, as compared to patients without radiculopathy. Receiver operating characteristic curves demonstrated good diagnostic accuracy, with areas under the curve of 0.85 and 0.82, respectively. Optimal cut-offs for electromyographically confirmed C8 and L5 radiculopathies were 10.2 mV and 3.6 mV, respectively, with associated sensitivities/specificities of 0.86/0.74 and 0.92/0.60.

DISCUSSION

Ulnar and fibular motor amplitudes may have clinical utility in assessing the likelihood of patients demonstrating electromyographically confirmed C8 and L5 radiculopathies with active denervation. The findings may be particularly useful in patients intolerant of needle electromyography. Muscle Nerve 59:561-561, 2019.

The Value of Electrodiagnostic Studies in Predicting Treatment Outcomes for Patients with Spine Pathologies

The utility of electrodiagnostic testing for spine pathologies varies based on the underlying suspected pathology. This article reviews the data on electrodiagnostic testing for common spine pathologies, with a specific focus on the prognostic data with regard to treatment outcomes. This information is placed into context of diagnostic confidence, which is derived from the combination of disease prevalence and the sensitivity and specificity of a test.

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.

Radiculopathy of the eighth cervical nerve

STUDY DESIGN

Resident's case problem.

BACKGROUND

The C8 nerve root is the least commonly encountered of cervical radiculopathies. The purpose of this resident's case problem is to provide an unusual presentation of a C8 radiculopathy, without cervical or proximal upper quarter symptoms, diagnosed by a combination of physical examination, electromyography (EMG) and nerve conduction studies (NCSs), and imaging.

DIAGNOSIS

A 49-year-old, right-hand-dominant male was referred to the EMG/NCS laboratory for a suspected left ulnar neuropathy at the elbow. A physical examination, NCS, and EMG were performed, and a C8 radiculopathy involving both the anterior and posterior primary rami was identified. Following the EMG and NCS evaluation, the patient had enhanced magnetic resonance imaging studies that confirmed a foraminal C7-T1 herniation and associated small central disc protrusion. The patient was then referred to neurosurgery for further consultation and subsequent surgical intervention. The patient underwent a C7-T1 laminectomy, mesial facetectomy, and foraminotomy, and excision of a herniated disk using an operating microscope. The neurosurgeon noted that there was a large disk herniation containing some disk material immediately anterior to the C8 motor root, that impinged directly on the motor root. One month postoperatively, the patient had decreased pain and numbness and tingling in his arm and his hand weakness had improved.

DISCUSSION

The report illustrates the utility of a combination of physical examination, EMG and NCSs, and imaging in the diagnosis of a C8 radiculopathy in a patient presenting with forearm and hand symptoms but without cervical or upper quarter symptoms.

LEVEL OF EVIDENCE

Diagnosis, level 4.

Anatomical and electrophysiological myotomes corresponding to the flexor carpi ulnaris muscle

This study was designed to investigate the incidence of lateral root of the ulnar nerve through cadaveric dissection and to analyze its impact on myotomes corresponding to the flexor carpi ulnaris (FCU) assessed by electrodiagnostic study. Dissection of the brachial plexus (BP) was performed in 38 arms from 19 cadavers, and the connecting branches between the lateral cord and medial cord (or between lateral cord and ulnar nerve) were investigated. We also reviewed electrodiagnostic reports from January 2006 to May 2008 and selected 106 cases of single-level radiculopathy at C6, C7, and C8. The proportion of abnormal needle electromyographic findings in the FCU was analyzed in these patients. In the cadaver study, branches from the lateral cord to the ulnar nerve or to the medial cord were observed in 5 (13.1%) of 38 arms. The incidences of abnormal electromyographic findings in the FCU were 46.2% (36/78) in C7 radiculopathy, 76.5% (13/17) in C8 radiculopathy and 0% (0/11) in C6 radiculopathy. In conclusion, the lateral root of the ulnar nerve is not an uncommon anatomical variation of the BP and the FCU commonly has the C7 myotome. Needle EMG of the FCU may provide more information for the electrodiagnosis of cervical radiculopathy and brachial plexopathy.

Musculoskeletal disorders in referrals for suspected cervical radiculopathy

OBJECTIVES

To determine (1) the prevalence of selected common musculoskeletal disorders in patients referred for electrodiagnosis when cervical radiculopathy is suspected and (2) whether these findings predict electrodiagnostic study outcome.

DESIGN

Prospective study.

SETTING

Electrodiagnostic laboratories in departments of physical medicine and rehabilitation at 5 participating institutions.

PARTICIPANTS

A total of 191 subjects undergoing electrodiagnostic evaluations for upper-limb symptoms when cervical radiculopathy was suspected.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Prevalence of certain musculoskeletal disorders (myofascial pain, shoulder impingement, lateral epicondylitis, de Quervain's tenosynovitis) and outcomes of electrodiagnostic testing (normal study, cervical radiculopathy, or another electrodiagnostically confirmed diagnosis).

RESULTS

The total prevalence of musculoskeletal disorders was 42%. The prevalence in those with a normal study was 69%, compared with 29% in those with cervical radiculopathy (P<.001) and 45% in those with another diagnosis (P=.02).

CONCLUSIONS

Musculoskeletal disorders are common in patients with suspected cervical radiculopathy. Although the presence of certain musculoskeletal disorders makes having a normal electrodiagnostic evaluation significantly more likely, the high prevalence among both patients with normal studies and those with radiculopathy and other disorders limits the usefulness of this information in precisely predicting study outcome. The presence of musculoskeletal disorders should not preclude electrodiagnostic testing when otherwise indicated.

Impact of electromyographic findings on choice of treatment and outcome

The subsequent clinical course of patients examined in the EMG laboratory has not been adequately studied before. It is not known how EMG findings in practice affect patients' final diagnosis, treatment and outcome. The aim of the present study was to test the hypothesis that EMG results have an important impact on the choice of patients' treatment and on outcome. Three years after EMG examination, a short questionnaire asking about initial symptoms, the final diagnosis, treatment and current symptoms was sent to 300 consecutive EMG patients. Responses concerning 186 of them (39% men) were received either from patients and/or from their referring physicians. Information obtained during EMG examination was also added. Data was analyzed using methods of bivariate and multivariate statistics. We found that patients with a pathologic EMG had a better clinical outcome 3 years later. Pathologic EMG has an independent effect, pointing to more favorable disease courses, which was further improved by more active treatment approaches received by these patients. The study demonstrated the important impact of EMG findings on the treatment choice and clinical outcome in population consisting mainly of patients with carpal tunnel syndrome and radiculopathy. Studies in other patient populations are needed.

The logical choice of muscles for the needle-electromyography evaluation of cervical radiculopathy

OBJECTIVE

To find the theoretically smallest subsets of muscles for needle-electromyography screening of cervical radiculopathies that meet or exceed the American Association of Electrodiagnostic Medicine (AAEM) guideline: ascertaining that each root and its adjacent roots are represented by at least 2 muscles each, innervated by those roots via different peripheral nerves.

DESIGN

Twenty-two and 36 muscle sets and their myotomal innervation were derived from the literature, and rearranged into 15 and 23 unique muscle groups by root and peripheral nerve innervation. All 2 circumflex 15 and 2 circumflex 23 subsets thereof were respectively identified. The best approximations that met or exceeded the AAEM criteria were computed for each subset and the smallest subsets that qualified were retained.

SETTING

Electromyography laboratory.

PARTICIPANTS

None.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

Compliance with or exceeding the AAEM guideline in the number of muscles sampled per damaged root and the number of muscles sampled per adjacent normal roots.

RESULTS

The smallest subsets satisfying or exceeding the AAEM guideline are of 8, 9, and 10 muscles each, and are enumerated in tables 3 and 4 in this article.

CONCLUSIONS

Electromyographers may choose a set or sets from tables in this article that best suits them, with confidence that they comply with or exceed the AAEM guideline while causing minimal pain to their patients and using the shortest possible procedure. All the roots can be screened at once to best differentiate between normal and damaged roots, and, in most cases, to reach a final diagnosis. Nonetheless, when needed, each set may be the basis for a more extensive workup.

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.