Cervical paraspinal spontaneous activity in asymptomatic subjects

Electrodiagnostic studies and new diagnostic modalities for evaluation of peripheral nerve disorders

Electrodiagnostic studies (EDx) are frequently performed in the diagnostic evaluation of peripheral nerve disorders. There is increasing interest in the use of newer, alternative diagnostic modalities, in particular imaging, either to complement or replace established EDx protocols. However, the evidence to support this approach has not been expansively reviewed. In this paper, diagnostic performance data from studies of EDx and other diagnostic modalities in common peripheral nerve disorders have been analyzed and described, with a focus on radiculopathy, plexopathy, compressive neuropathies, and the important neuropathy subtypes of Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), vasculitic neuropathy and diabetic neuropathy. Overall EDx retains its place as a primary diagnostic modality in the evaluated peripheral nerve disorders. Magnetic resonance imaging and ultrasound have developed important complementary diagnostic roles in compressive and traumatic neuropathies and atypical CIDP, but their value is more limited in other neuropathy subtypes. Identification of hourglass constriction in nerves of patients with neuralgic amyotrophy may have therapeutic implications. Investigation of radiculopathy is confounded by poor correlation between clinical features and imaging findings and the lack of a diagnostic gold standard. There is a need to enhance the literature on the utility of these newer diagnostic modalities.

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.

Anatomical study and proposed EMG technique for the cervical paraspinal muscles

Paraspinal electromyography has proven to be the most sensitive component of the electrodiagnostic examination for lumbar spinal disorders. However, no standardized, anatomically validated technique has been proposed for the cervical region. This study reviewed the published textbooks on cervical paraspinal anatomy to develop a standardized electromyography technique and scoring system. A library search found 32 anatomy texts published between 2000 and 2021. Of these 11 were unique and appropriate. Most texts described the basic muscle anatomy similarly, but only one cited original research. When the spinous process is defined as the origin, the multifidus and deeper rotatores appear innervated by the posterior primary rami of single cervical roots. However, texts differ in the number of pennae, between two and five, traveling to transverse process regions below. These are crowded into a small area between the spinous processes and transverse processes. Based on this understanding, a proposed cervical paraspinal mapping technique involves skin insertions from 1 to 2 cm lateral to the C5, C7, and T2 spinous processes. The needle samples transversely and deep toward midline, contacts bone, then is withdrawn and redirected to sample medial and caudally to midline to bone, creating two scores of 0-4 at three levels, theoretically resulting in scores of 0-24. This technique must be validated by clinical research to determine the range of normal, reproducibility, and the spectrum of findings in various disorders.

A Cadaveric Study of a Safe and Accurate Electromyographic Needle Approach to the Rhomboid Major

OBJECTIVE

This study aimed to investigate a safe and accurate electromyographic needle insertion site of the rhomboid major (RM) muscle using cadaver dissection.

DESIGN

Dissection of the trapezius and rhomboid major muscles around the scapula was performed in 18 scapulae from nine fresh cadavers. The point (point A) at which the lateral margin of the lower trapezius muscle crossed the medial border of the scapula and the distal insertion point (point DI) of the rhomboid major muscle to the medial scapula were determined. The midpoint (point M) between points A and DI was also determined. The distance from the inferior angle of the scapula to each point was measured.

RESULTS

The length of the medial scapula was 12.9 ± 1.2 cm from the root of the scapular spine to the inferior angle of the scapula. Points A, DI, and M were located at a mean distance of 8.4 ± 0.7, 1.8 ± 0.4, and 5.1 ± 0.5 cm proximal to the inferior angle of the scapula, respectively.

CONCLUSIONS

Needle electromyographic examination of the rhomboid major muscle can be performed safely and accurately using the lower part of the rhomboid major muscle, as investigated in this anatomical study.

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

The electrodiagnostic (EDX) examination with needle electromyography (EMG) is the most important means of testing for radiculopathy. This test has modest sensitivity but high specificity and complements imaging of the spine. In this second of a two-part review, the implications of electrodiagnostic findings for diagnosis and clinical management of persons with radiculopathy are reviewed. An EMG confirmed lumbosacral radiculopathy is associated with better clinical outcomes for persons undergoing aggressive conservative management. A positive EMG test portends a better clinical response to epidural corticosteroid injections. If a person undergoes spine surgery, a positive pre-operative EMG for radiculopathy is also associated with better outcomes.

Quantitative electromyography: Normative data in paraspinal muscles

BACKGROUND

Quantitative electromyography of paraspinal muscle is a valuable diagnostic tool, but normative data are lacking.

METHODS

Needle electromyography (EMG) was obtained in 65 healthy subjects (49% men, 51% women) aged 21 to 82 years at C7, Th10, and L5 segments bilaterally. The incidence of spontaneous activity; motor unit potential (MUP) amplitudes, durations, and the incidence of polyphasic potentials; and the recruitment pattern at maximal voluntary contraction (MVC) were evaluated.

RESULTS

The incidence of fibrillation potentials was similar to limb muscles. The mean MUP duration and amplitude, and the amplitude at MVC increased caudally, while the incidence of polyphasic potentials was similar at all levels. EMG parameters did not correlate with sex or age.

CONCLUSIONS

In contrast to limb muscles, EMG parameters did not change with age, while polyphasic potentials were more frequent in paraspinal muscle than in limb muscles. The EMG gradient suggests larger motor units at more caudal segments.

Average proportional consecutive interval difference accurately differentiates spontaneous activity from motor unit potentials

INTRODUCTION

An objective method is required to detect spontaneous activity (SA) for prevalence studies in needle electromyography (EMG). Because of frequent similarities in the morphology of SA and motor unit potentials (MUP), identification of SA depends on assessment of firing regularity, which has not yet been quantitated through a modern interface.

METHODS

Prospective recordings obtained from patients referred for electrodiagnostic evaluation were analyzed by using decomposition-based quantitative EMG (DQEMG) customized to calculate descriptive statistics.

RESULTS

Forty-four MUP recordings (39 participants) and 80 SA recordings (62 participants) were analyzed. One hundred one of 124 recordings successfully interfaced with DQEMG. The remaining recordings were analyzed in Audacity. Average proportional consecutive interval differences differentiated SA from MUPs with 97.5% sensitivity (confidence interval [CI] 91.3%-99.7%) and 100.0% specificity (CI 92%-100%). There was substantial overlap, however, for SD and mean consecutive differences.

DISCUSSION

Average proportional consecutive interval difference accurately differentiates SA from MUPs and may be useful in future prevalence studies of SA.

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.

A More Precise Electromyographic Needle Approach for Examination of the Rhomboid Major

BACKGROUND

Safe and accurate needle access to the rhomboid major (RM) during electromyography is challenging due to the overlying trapezius muscle and the risk of pneumothorax.

OBJECTIVE

To investigate the RM anatomy associated with the trapezius using ultrasonography and to determine a safe and accurate needle insertion point for needle electromyography of the RM.

DESIGN

Descriptive study.

SETTING

Department of physical medicine and rehabilitation of a tertiary clinic center.

PARTICIPANTS

Participants between 23 and 71 years of age without any diseases (N = 25; 13 men, 12 women; 50 scapulae) were included.

INTERVENTIONS

Ultrasonography of the RM and trapezius muscles around the scapula.

MAIN OUTCOME MEASURES

The point at which the lateral margin of the trapezius crosses the medial border of the scapula (point A) was determined. The probe was positioned at the level of the midpoint (point M) between point A and the inferior angle of the scapula. The horizontal distance from the point at which the RM was the thickest (point X) to point M was measured. At point X, the depth of the RM, RM thickness, and the depth of the pleura were measured.

RESULTS

The mean age and body mass index were 37.4 ± 12.0 years and 22.3 ± 2.1 kg/m², respectively. Point M was located at a mean distance of 3.9 ± 0.6 cm proximal to the inferior angle of the scapula. The mean distance between point X and point M was 1.0 ± 0.2 cm. At point X, the RM was at a mean depth of 9.7 ± 3.1 mm from the skin and had a mean thickness of 9.9 ± 1.8 mm. The pleura was observed at a mean depth of 28.4 ± 3.8 mm from the skin.

CONCLUSION

Needle electromyographic examination of the RM can be performed easily and safely through the lower part of the RM that is not covered by the trapezius.

LEVEL OF EVIDENCE

not applicable.

A Rare Case of T1-2 Thoracic Disc Herniation Mimicking Cervical Radiculopathy

Introduction

Thoracic disc herniation is not as common as other disc herniations seen at other levels of spinal column. Th1-Th2 disc herniation is an extremely rare condition. Physical and cautious radiological examination is significantly important for diagnosis.

Case Presentation

We report a 45 years old male case with complaint of neck pain radiating to right upper extremity. The physical examination revealed Th1 radiculopathy symptoms. According to his images degeneration at C6-7 level and right T1 root compression due to Th1-Th2 disc herniation at foraminal region were evaluated. The patient underwent hemilaminectomy, foraminatomy and discectomy at T1-T2 level via posterior approach.

Conclusion

T1-2 level thoracic disc herniation can accompany with cervical region problems and some syndromes can mimic Th1 radiculopathy symptoms. The aim of this case report is to keep on mind of this rare condition and to emphasize the importance of physical findings and correlations with magnetic resonance imaging.

EMG/NCS in the evaluation of spine trauma with radicular symptoms

In the management of spine trauma with radicular symptoms (STRS), EMG/nerve conduction studies (NCS) often have low combined sensitivity and specificity in confirming root injury. The anatomic level of injury may not correspond to the root level. Paraspinal studies are nonlocalizing and can be falsely positive and negative. Unlike MRI and CT imaging, EMG/NCS do not reveal the biological morphology of the lesion. There are no studies that confirm the efficacy of EMG/NCS in the management of STRS. EMG/NCS may be indicated if there is a differential diagnosis between a root and distal neuropathic/myopathic lesion. Otherwise, as shown in this series of cases typically referred for outpatient EMG/NCS testing, there is limited evidence to support the use of often uncomfortable and costly EMG/NCS in STRS.

Pitfalls in using electrophysiological studies to diagnose neuromuscular disorders

Electrodiagnostic testing is used widely for the full characterization of neuromuscular disorders and for providing unique information on the processes underlying the pathology of peripheral nerves and muscles. However, such testing should be considered as an extension of anamnesis and physical examination, not as pathognomonic of a specific disease entity. There are many pitfalls that could lead to erroneous interpretation of electrophysiological study results when the studies are not performed properly or if they are performed in the presence of anatomical aberrations. The diagnostic reliability of electrodiagnostic studies can be improved and the associated pitfalls overcome if the physician is familiar with all of those possible pitfalls. In this article we discuss the most common and important pitfalls associated with electrodiagnostic medicine.

Sonographic measurements of the thickness of the soft tissues of the interscapular region in a population of normal young adults

BACKGROUND

To use sonography (US) to measure the interscapular soft-tissue thickness and to determine any correlation with anthropometric indices.

METHODS

Fifty-five healthy young adults (21 men and 34 women) with a mean age of 22.1 ± 3.0 years (range, 18-35) were enrolled. High-resolution US was used to measure the bilateral soft-tissue thickness near the medial border of the scapula. Anthropometric indices, including body weight, height, and circumferences of chest, waist, and hip, were also measured.

RESULTS

On the right side, mean values ± standard deviation for the thickness of the trapezius, rhomboid, and posterior serratus muscles in millimeters were 4.9 ± 1.0, 6.3 ± 2.3, and 3.5 ± 1.4, respectively, for men and 3.4 ± 0.8, 3.8 ± 1.7, and 2.2 ± 1.5, respectively, for women. The thickness of each muscle was significantly greater in men than in women (p < 0.05). For both genders, no significant differences in the soft-tissue thicknesses were found between both sides. Based on the anthropometric indices, body weight was the only significant contributor to the soft-tissue thickness.

CONCLUSIONS

US is a practical tool for measuring soft-tissue thickness in the interscapular region. Body weight and soft-tissue thickness are closely associated.

Association of paraspinal and diaphragm denervation in ALS

Paraspinal EMG needle examination is commonly performed in amyotrophic lateral sclerosis (ALS) for diagnosis. Because lower motor neurons for axial muscles and diaphragm are located medially in the anterior horn, we tested if involvement of axial muscles is associated with diaphragm weakness in ALS. Forty-four ALS patients were included with ALSFRS greater than 20/40. We used needle EMG to search for signs of denervation in biceps, tibialis anterior, C6 and T5 paraspinal muscles, and intercostal and diaphragm muscles. We also evaluated phrenic nerve motor responses and forced vital capacity (FVC). We tested specificity, sensitivity, and discriminative strength (ROC analysis). Fibs-sw in C6 and T5 paraspinal muscles, as well as fibs-sw in diaphragm and intercostal muscles showed high specificity and positive predictive value for FVC<80%. Discriminative strength was good for all the above tests, as well as for phrenic nerve amplitude and ALSFRS regarding FVC<80%. Axial muscles denervation is related to diaphragm denervation and therefore to poor respiratory function in ALS. We suggest that medially located lower motor neurons are affected concurrently in ALS.

The Electrodiagnosis of Cervical and Lumbosacral Radiculopathy

This article reviews the usefulness of the electrodiagnostic examination in patients who have suspected cervical and lumbosacral radiculopathy. This study can verify the presence and severity of radiculopathy, determine which levels are involved, and provide an electrodiagnostic correlate to imaging abnormalities. A practical approach for conducting the nerve conduction portion and needle electrode examination in these patients is discussed.