Conventional Needle Electromyography Research Articles

Optimal needle electromyography approach to the serratus anterior muscle.

There are two conventional needle electromyography (EMG) approaches to the serratus anterior (SA), both of which can result in erroneous insertion into adjacent structures such as the latissimus dorsi (LD), teres major, or external oblique abdominis muscles and pose a risk of long thoracic nerve (LTN) injury. Therefore, we identified a novel needle insertion point for the SA in cadavers that avoids other muscles and LTN injury. This study included 17 cadavers: 12 to devise the new method and 5 to verify its accuracy. Novel landmarks were the inferior angle of the scapula (I), sternal notch (S), and xiphoid process (X). The relationships of the LD, pectoralis major (PM), SA, and LTN were determined relative to these landmarks. When inserting a needle into the proximal one third along the line connecting points I and X, there were adequate safety margins around the LD, PM, and LTN, and the new method had excellent accuracy. Compared to the conventional midaxillary method, our novel method improved the accuracy of needle EMG of the SA. Follow-up studies using clinical imaging techniques are needed to verify whether above findings are equally applicable in living subjects.

Pilot study of a novel transmembranous electromyography device for assessment of oral cavity and oropharyngeal muscles

Electromyography (EMG) can provide valuable insights into the pathophysiology of oropharyngeal muscles in various disease states, but the invasive nature of the conventional needle EMG (nEMG) has its limitations in this setting. We aimed to examine the inter-rater reliability (IRR) of a novel transmembranous EMG (tmEMG) sensor as a non-invasive technique for assessment of oral cavity and oropharyngeal muscles for neuromuscular pathology. The study was a prospective, cohort, pilot study with blinded data analysis in healthy participants (n=6), patients with moderate to severe obstructive sleep apnea (OSA) (n=5) and bulbar amyotrophic lateral sclerosis (ALS) (n=5). Each patient underwent sampling from bilateral palatoglossus (PG) and genioglossus (GG), using both tmEMG and nEMG. IRR was expressed as percentage agreement and prevalence-adjusted bias-adjusted kappa coefficient (PABAK). Substantial IRR was found for participants with ALS (81.6%, PABAK 0.63) and OSA (78.8%, PABAK 0.61), and in healthy participants (87.1%, PABAK 0.74). A better IRR was seen with tmEMG (95.7%, PABAK 0.92) than with nEMG (73.9%, PABAK 0.48) for healthy participants and also for those with OSA. Studies from GG had higher IRR than PG. Only one participant had a minor adverse event (sore throat). The current study shows that analysis of PG and GG in both healthy and disease states using tmEMG has high IRR compared with nEMG analysis. Further validation studies can be undertaken to test its utility in analysis of oral cavity and oropharyngeal muscles.

Optically pumped magnetometers reveal fasciculations non-invasively

ObjectiveThis proof-of-principle-study evaluated the extent to which spontaneous activity (SA) of the muscle can be detected via non-invasive magnetomyography (MMG) with optically pumped magnetometers (OPM). MethodsFive patients, who together exhibited all forms of SA (fibrillations, positive sharp waves, fasciculations, myotonic discharges, complex-repetitive discharges) with conventional needle electromyography (EMG), were studied by OPM-MMG and simultaneous surface EMG (sEMG) while at rest, during light muscle activation, and when a muscle stretch reflex was elicited. Three healthy subjects were measured as controls. SA was considered apparent in the OPM-MMG if a signal could be visually detected that corresponded in shape and frequency to the SA in the respective needle EMG. ResultsSA in the context of fasciculations could be detected in 2 of 5 patients by simultaneous OPM-MMG/sEMG. Other forms of SA could not be detected at rest, during light muscle activation, or after provocation of a muscle stretch reflex. ConclusionsResults show that fasciculations could be detected non-invasively via a new method (OPM). SignificanceWe show that other forms of SA are not detectable with current OPM and propose necessary technical solutions to overcome this circumstance. Our results motivate to pursue OPM-MMG as a new clinical neurophysiological diagnostic.

Cervical Intraspinal Conduction Time by Magnetic Root Stimulation versus Conventional Electromyography in the Diagnosis of Cervical Radiculopathy

Background: Cervical radiculopathy (CR) is a pathological procedure that encompasses root of the cervical nerve. Cervical disc herniation, accompanied by cervical spondylosis, is among the most common causes of radiculopathy. Clinical neurophysiology is a medical field focused mainly on assessing activity in the nervous system and muscles being an expansion of neurological assessment, using particular same anatomical localization criteria as clinical testing. Objective: To evaluate the sensitivity and specificity of conduction time of the intraspinal segment of peripheral motor neurons in the diagnosis of CR using cervical root magnetic stimulation and conventional electromyography (EMG) study. Methods: Fifty patients (15 males and 35 females) aged 46.02±9.76 years with reported CR were subjected to an electrophysiological examination and control group consisted of 50 (36 females and 14 males) healthy volunteers aged 36.24±12.09 years. Analysis of sensory and motor nerve conduction, conventional needle EMG test, and motor evoked potentials (MEPs) for all (recording abductor pollicis brevis (APB), abductor digiti minimi (ADM), biceps brachii (BB), deltoid muscles) was conducted to determine the peripheral nerves, muscles, sensory and motor pathways. The motor evoked potential (MEP) parameters studied for the median, ulnar musculocutaneous and axillary nerves include latency of the spinal root {peripheral motor conduction time} (PMCT). Results: During direct cervical root stimulation, the PMCT of the median nerve shows the highest specificity (59%) than that of the ulnar nerve (57%), while the intraspinal latency shows the same specificity for both nerves (57%). In comparison, PMCT by kimura formula recording ADM during direct stimulation of the cervical root have the highest sensitivity (56%) than that of PMCT by kimura formula recording APB. Additionally, the recording of direct cervical root stimulation amplitude after deltoid muscle showed the highest specificity and sensitivity (57.0%, 58.0% respectively). On the other hand, PMCT shows the highest specificity and sensitivity while the BB muscle is recoded (62.0%, 49.0%). Conclusion: Overall, the current motor evoked potential study shows abnormalities in less than 60% of patients with cervical radiculopathy relative to conventional EMG needle study abnormalities that reached 90%. The intraspinal latency of the median and ulnar show low sensitivity and specificity. Keywords: Cervical radiculopathy, electromyography, motor evoked potentials Citation: Abdulhameed AK, Kaddori HG. Cervical intraspinal conduction time by magnetic root stimulation versus conventional electromyography in the diagnosis of cervical radiculopathy. Iraqi JMS. 2021; 19(1): 60-71. doi: 10.22578/IJMS.19.1.9

O-04 Peripheral movement disorders

Movement disorders are clinical syndromes which present either an increase or decrease of voluntary and involuntary movements. Although the neural mechanism underlying most of these syndromes involves the central nervous system, a much smaller group has a peripheral nervous system aetiology. While surface electromyography (EMG) is more conventionally used in movement disorders in order to characterize the abnormal muscle contractions, it is not as useful in the study movement disorders of peripheral origin. Nevertheless, conventional needle EMG provides information enough to determine the origin and suffices for diagnosis in these syndromes. We have revised all the movement disorders cases between 2015 and 2018. They were referred to our laboratory for a surface EMG study. In these period, 63 patients were studied. 3 of these patients (less than 5%) were finally diagnosed of a peripheral movement disorder. All the 3 patients were referred to the EMG department with the diagnosis of a central nervous system movement disorder. Due to the clinical examination, we suspected a peripheral involvement and thus, needle EMG was performed instead. EMG findings (fasciculations, fibrillations, normal MUPs) led to the diagnosis of a continuous muscle fibre activity syndrome of peripheral origin. Peripheral movement disorders are an infrequent condition and therefore difficult to suspect. Needle EMG studies are decisive for the correct diagnosis in this syndromes. Conventional needle EMG, even if not established as part of the diagnostic protocol, may contribute in those cases in which questions about a central or peripheral origin arise, since clinical manifestations often overlap.

S90 Quantified electromyography in children

In spite of recent advantages in molecular genetics, electromyography (EMG) still has diagnostic value, especially in children. Neuromuscular disorders in children are not common compared to in adults but they are important. Many of them are disabling disorders in which there is no cure, only supportive treatment. Such neuromuscular disorders affect not only the patient, but the whole family, often because of increased care load. In addition to these chronic disorders, of which many have a genetic background, there are acute and subacute traumatic disorders and immunopathies. In children, every medical procedure may induce anxiety. It is therefore important that one or both parents are present at the investigation in order to support their child. It is advisable to apply a local anaesthetic prior to EMG. Pain relief may be needed to give before EMG (e.g. morphine). Controlled conscious sedation may sometimes be needed (e.g. midazolam, ketamine, nitrous oxide). In the majority of children, conventional needle EMG is used in order to study the motor unit properties. In a normal muscle at rest no abnormal spontaneous activity is identified. Thus, after the insertion activity has subsided, the muscle at rest is investigated for abnormal spontaneous activity which may occur in single muscle fibres or in a group of fibres. There may be abnormal spontaneous activity of different kinds in one and the same diseased muscle of neurogenic or myogenic origin. Ten different places in each muscle are examined, and the amount of abnormal spontaneous activity in these ten needle positions is measured. At slight voluntary activation motor unit potentilas (MUPs) are recruited. Preferably, about 20 MUPs are collected from each muscle in order to allow a thorough assessment. However, in children with severe disorders, and who activate only sporadically, it may not be possible to obtain more than a few MUPs. The MUPs are collected by quantitative method, sometimes mixed with a semiquantitative method, depending on the child’s co-operation. For each MUP there are different parameters to consider, e.g. amplitude, duration, shape and stability. Strong voluntary activation is used to study the interference pattern. It is difficult to perform this adequately in children, but, when feasible, it gives much information and complements the MUP analysis. Single-fbre EMG is a very useful and sensitive tool in the diagnosis of neuromuscular transmission disorders. It can be studied under voluntary activation or, particularly in children, with electrical stimulation. The oral communication will further elaborate on EMG and give practical tips.

Lower motor neuron dysfunction in ALS.

In the motor system there is a complex interplay between cortical structures and spinal cord lower motor neurons (LMN). In this system both inhibitory and excitatory neurons have relevant roles. LMN loss is a marker of motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). Conventional needle electromyography (EMG) does not allow LMN loss to be quantified. Measurement of compound muscle action potential (CMAP) amplitude or area, and the neurophysiological index, provide a surrogate estimate of the number of functional motor units. Increased motor neuronal excitability is a neurophysiological marker of ALS in the context of a suspected clinical and electrophysiological diagnosis. In the LMN system, fasciculation potentials (FPs) are the earliest changes observed in affected muscles, a feature of LMN hyperexcitability. Reinnervation is best investigated by needle EMG although other methods can be explored. Moreover needle EMG give information about the temporal profile of the reinnervation process, important ancillary data. Quantitative motor unit potential analysis is a valuable method of evaluating reinnervation. The importance of FPs has been recognized in the Awaji criteria for the electrodiagnosis of ALS, criteria that are a sensitive adjunct to the revised El Escorial criteria. Finally, functionality of LMN's, and perhaps excitability studies in motor nerves, aids understanding of the disease process, allowing measurement of potential treatment effects in clinical trials. Other investigational techniques, such as electrical impedance myography, muscle and nerve ultrasound, and spinal cord imaging methods may prove useful in future.

Outcomes of Neonatal Bulbar Weakness.

Neonatal bulbar weakness (BW) has various etiologies and a broad prognostic range. We aimed to report outcomes in a large series of children with neonatal BW and explore the association of orofacial electrodiagnostic data with outcome. We retrospectively reviewed the files of children who presented with facial, lingual, laryngeal, or pharyngeal weakness at birth and who underwent electrodiagnostic studies combining conventional needle electromyography (EMG) of orofacial muscles, blink responses, and EMG during bottle-feeding. Outcome measures included the need for prolonged respiratory assistance and enteral feeding, as well as sensorimotor and cognitive impairments. Of 175 patients, 73% had developmental disorders, 25% suffered from acquired brain damage, and 2% had no apparent underlying disorders. Motor or mental impairment was observed in 71%; death occurred in 16%. Outcomes were not significantly different when comparing developmental disorders versus acquired brain damage or neurogenic versus normal detection EMG. Abnormal blink responses were associated with higher frequencies of respiratory assistance (P = .03), gastrostomy (P = .025), and death (P = .009); moderate or severe oropharyngeal incoordinations were associated with higher frequencies of respiratory assistance (P = .006), prolonged enteral feeding (P < .0001), and gastrostomy (P = .0002). Orofacial electrodiagnostic studies provide supplementary information to help the pediatrician anticipate the management and prognosis of young infants with BW.

Endomicroscopy and electromyography of neuromuscular junctions in situ.

ObjectiveElectromyography (EMG) is used routinely to diagnose neuromuscular dysfunction in a wide range of peripheral neuropathies, myopathies, and neuromuscular degenerative diseases including motor neuron diseases such as amyotrophic lateral sclerosis (ALS). Definitive neurological diagnosis may also be indicated by the analysis of pathological neuromuscular innervation in motor-point biopsies. Our objective in this study was to preempt motor-point biopsy by combining live imaging with electrophysiological analysis of slow degeneration of neuromuscular junctions (NMJs) in vivo.MethodsWe combined conventional needle electromyography with fiber-optic confocal endomicroscopy (CEM), using an integrated hand-held, 1.5-mm-diameter probe. We utilized as a test bed, various axotomized muscles in the hind limbs of anaesthetized, double-homozygous thy1.2YFP16: WldS mice, which coexpress the Wallerian-degeneration Slow (WldS) protein and yellow fluorescent protein (YFP) in motor neurons. We also tested exogenous vital stains, including Alexa488-α-bungarotoxin; the styryl pyridinium dye 4-Di-2-Asp; and a GFP conjugate of botulinum toxin Type A heavy chain (GFP-HcBoNT/A).ResultsWe show that an integrated EMG/CEM probe is effective in longitudinal evaluation of functional and morphological changes that take place over a 7-day period during axotomy-induced, slow neuromuscular synaptic degeneration. EMG amplitude declined in parallel with overt degeneration of motor nerve terminals. EMG/CEM was safe and effective when nerve terminals and motor endplates were selectively stained with vital dyes.InterpretationOur findings constitute proof-of-concept, based on live imaging in an animal model, that combining EMG/CEM may be useful as a minimally invasive precursor or alternative to motor-point biopsy in neurological diagnosis and for monitoring local administration of potential therapeutics.

Is It Useful to Stimulate Roots in the Diagnosis of Cervical Root Compression?

Electrophysiology can be very important in diagnosing root pathologies, but the classic electrophysiologic methods lack an objective measurement tool. In this study, diagnostic validity of cervical spinal root stimulation (CRS) was evaluated in patients with suspected cervical radiculopathy. CRS, conventional needle electromyography, and magnetic resonance imaging were performed in 14 patients. The control group included 10 healthy individuals. A monopolar needle electrode was used for the CRS. Compound muscle action potentials were recorded from biceps, triceps, and abductor digiti minimi muscles. Thirty root pairs in the control group and 40 root pairs in the patient group were stimulated. Latencies and amplitudes of the compound muscle action potentials were found abnormal in 5 (35.7%) and 10 (71.4%) patients, respectively. Electromyographic findings of root compression were seen in 10 patients (71.4%). The CRS results were positive in 7 out of 10 patients with positive electromyography findings of root dysfunction. Our results suggest that CRS may be a complementary diagnostic tool. Technical difficulties and lack of reference data make its use difficult as a routine electrophysiologic test for diagnosing nerve root dysfunction.

Needle electromyography of the rectus abdominis in patients with amyotrophic lateral sclerosis

We examined the role of needle electromyography (EMG) of the rectus abdominis (RA) in assessing thoracic involvement in amyotrophic lateral sclerosis (ALS). Needle EMG of the RA was performed in 67 patients with sporadic ALS and 110 healthy controls. The presence of abnormal spontaneous activity, configuration of motor unit action potentials (MUAPs), and recruitment pattern of motor unit potentials were examined. In ALS patients, MUAPs in the RA were of prolonged duration, large amplitude, and showed increased prevalence of polyphasic waveforms compared to controls. Significant differences in MUAP parameters, presence of abnormal spontaneous potentials, and interference patterns were noted between ALS patients and controls. Additionally, we found that active denervation was more frequent in the RA of ALS patients with dyspnea than those without dyspnea. Thus, conventional needle EMG of the RA is a valuable electrophysiological method to assess clinical and subclinical involvement of thoracic lower motor neurons in patients with suspected ALS.

Electrodiagnostic approach to the patient with suspected neuromuscular junction disorder

The electrodiagnostic (EDX) examination in patients with suspected Neuromuscular Junction (NMJ) disorder constitutes the most advanced and complex type of EDX studies. Understanding the anatomy and physiology of neuromuscular transmission is prerequisite for the comprehension and planning of EDX studies in patients with suspected NMJ disorders. In addition to routine nerve conduction studies and conventional needle electromyography (EMG), the EDX studies, which are most useful in the diagnosis of NMJ disorders, include repetitive nerve stimulation and single fiber EMG.

The role of electromyography (EMG) in the diagnosis of ALS.

Electromyography (EMG) plays a key role in the diagnostic evaluation of ALS. This paper deals with the contribution of conventional needle EMG and electroneurography to the neurophysiological assessment of ALS. In addition, special EMG techniques such as single fibre EMG and macro EMG are discussed as they mirror the decline of the number of motor units during the disease process and the remodelling capacity of the surviving motor units.

Satellite potentials as a measure of neuromuscular disorders

The study was carried out to investigate the characteristics of satellite potentials and their validity in clinical electromyography. Conventional needle electromyography was applied to the right biceps brachii and tibialis anterior muscles of 41 controls, 22 neuropathies, and 17 myopathies. Satellites were defined as small extrapotentials, preceding/following the main motor unit action potential (MUAP) component and separated from it by an isoelectrical interval of >1 ms. The normal mean satellite rate was 1.6% biceps brachii) and 1.2% (tibialis anterior). In the biceps brachii (tibialis anterior) muscle it was 5 (5) times higher for neuropathies (P = 0.005, P = 0.006) and 5 (6) times higher for myopathies (P = 0.006, P = 0.003). MUAP parameters were not significantly different, whether satellites were considered or ignored. Evaluation of the satellite rate increased detection rates of neuromuscular disorders by up to 13%. The satellite rate proved a valuable and easily available, supplemental electromyographic parameter for the discrimination and detection of neuromuscular disorders. © 1997 John Wiley & Sons, Inc. Muscle Nerve 20, 585–592, 1997.

Satellite potentials as a measure of neuromuscular disorders.

The study was carried out to investigate the characteristics of satellite potentials and their validity in clinical electromyography. Conventional needle electromyography was applied to the right biceps brachii and tibialis anterior muscles of 41 controls, 22 neuropathies, and 17 myopathies. Satellites were defined as small extrapotentials, preceding/following the main motor unit action potential (MUAP) component and separated from it by an isoelectrical interval of > 1 ms. The normal mean satellite rate was 1.6% (biceps brachii) and 1.2% (tibialis anterior). In the biceps brachii (tibialis anterior) muscle it was 5 (5) times higher for neuropathies (P = 0.005, P = 0.006) and 5 (6) times higher for myopathies (P = 0.006, P = 0.003). MUAP parameters were not significantly different, whether satellites were considered or ignored. Evaluation of the satellite rate increased detection rates of neuromuscular disorders by up to 13%. The satellite rate proved a valuable and easily available, supplemental electromyographic parameter for the discrimination and detection of neuromuscular disorders.

Evoked fasciculations in patients with amyotrophic lateral sclerosis

In the motor system there is a complex interplay between cortical structures and spinal cord lower motor neurons (LMN). In this system both inhibitory and excitatory neurons have relevant roles. LMN loss is a marker of motor neuron disease/amyotrophic lateral sclerosis (MND/ALS). Conventional needle electromyography (EMG) does not allow LMN loss to be quantified. Measurement of compound muscle action potential (CMAP) amplitude or area, and the neurophysiological index, provide a surrogate estimate of the number of functional motor units. Increased motor neuronal excitability is a neurophysiological marker of ALS in the context of a suspected clinical and electrophysiological diagnosis. In the LMN system, fasciculation potentials (FPs) are the earliest changes observed in affected muscles, a feature of LMN hyperexcitability. Reinnervation is best investigated by needle EMG although other methods can be explored. Moreover needle EMG give information about the temporal profile of the reinnervation process, important ancillary data. Quantitative motor unit potential analysis is a valuable method of evaluating reinnervation. The importance of FPs has been recognized in the Awaji criteria for the electrodiagnosis of ALS, criteria that are a sensitive adjunct to the revised El Escorial criteria. Finally, functionality of LMN’s, and perhaps excitability studies in motor nerves, aids understanding of the disease process, allowing measurement of potential treatment effects in clinical trials. Other investigational techniques, such as electrical impedance myography, muscle and nerve ultrasound, and spinal cord imaging methods may prove useful in future.

Motor evoked potentials following cervical electrical stimulation in brachial plexus lesions

The diagnostic relevance of recording motor evoked potentials (MEPs) after electrical stimulation of the cervical region, as compared with conventional needle electromyography (EMG), was evaluated in 26 patients with brachial plexus (BP) damage of different aetiology, severity and topography. MEP abnormalities (absence or latency increase) were observed in at least one muscle of all the patients, with a global incidence of 61.5% of the muscles examined. Neurogenic EMG signs were present in all but one patient with an incidence of 62.2% of the muscles examined. Combining the two methods, the global incidence of abnormalities rose to 69.9%. MEP abnormalities were consistent with the clinical topography and severity of BP lesions and were fairly parallel with EMG findings. Recording MEPs after percutaneous electrical stimulation of the cervical region may be regarded as a rapid, non-invasive method for quantitative electrophysiological assessment of BP damage.

Aspects electromyographiques des myosites a inclusions. Etude en macroelectromyographie

Histological and electrophysiological features in cases of inclusion body myositis are often difficult to interpret, suggesting either a "myogenic" or a "neurogenic" disorder. One case of inclusion body myositis is described. Conventional needle electromyography recording was interpreted as "neurogenic": abundant fibrillation potentials and positive sharp waves, reduced interference pattern, polyphasic-high amplitude-long duration motor unit potentials. Macro-EMG was performed in quadriceps muscle. Fibre density was normal and median value of the amplitude of macro motor unit potentials was increased, suggesting a larger size of motor units. Morphologic and electrophysiologic features indicate compensatory and regeneration mechanisms resulting in an increase of motor unit during the course of inclusion body myositis. This can explain atypical electromyographic and morphologic data in this disease.