Neurogenic Electromyography Research Articles

Electromyography varies by stage in inclusion body myositis.

Inclusion body myositis (IBM) is a chronic inflammatory muscle disease that is characterized by mixed myogenic and neurogenic electromyography (EMG) findings. We investigated the association between EMG findings and the IBM stage. We included consecutive patients diagnosed with IBM based on muscle biopsy and had needle EMG performed within 1 month of biopsy. Motor unit potential waveform (MUP) in EMG and pathological findings were compared between patients in early and late phases. In total, 30 patients with biopsy-confirmed IBM and 254 muscles were included. The rate of abnormal discharge did not differ according to disease stage. There was a difference in the frequency of occurrence between myogenic suggestive MUP and neurogenic of biceps and flexor digitorum profundus in the late phase. Abnormal MUP was observed even in muscles without muscle weakness, and myogenic changes were predominant in biceps and gastrocnemius with muscle weakness. The biopsy findings on the contralateral side of the muscle where electromyography was performed revealed a tendency for muscles that exhibited myogenic origin to have more inflammatory cells and RV; however, the difference was not significant. The target muscles for EMG must be selected considering the disease stage as well. In the early stages of IBM, EMG results should be interpreted cautiously, as neurogenic suggestive pattern of MUP might also be exhibited. Contralateral electromyography findings may be helpful in selecting muscles for muscle biopsies, such as biceps and quadriceps.

Comparison of muscle ultrasound and needle electromyography findings in neuromuscular disorders.

Needle electromyography (EMG) and muscle ultrasound can be used to evaluate patients with suspected neuromuscular disorders. The relation between muscle ultrasound pathology and the corresponding needle EMG findings is unknown. In this study we compared the results of concurrent ultrasound and needle EMG examinations in patients suspected of a neuromuscular disorder. Retrospective data from 218 patients with pairwise ultrasound and EMG results of 796 muscles were analyzed. We compared overall quantitative and visual muscle ultrasound results to EMGs with neurogenic and myopathic abnormalities and assessed the congruency of both methods in the different clinical diagnosis categories. In muscles of patients with a neuromuscular disorder, abnormalities were found with EMG in 71.8%, and quantitative and visual muscle ultrasound results were abnormal in 19.3% and 35.4% respectively. In muscles with neurogenic EMG abnormalities, quantitative and visual muscle ultrasound results were abnormal in 18.9% versus 35.6%, increasing up to 43.7% versus 87.5% in muscles with the most pronounced signs of denervation. Congruency of EMG and ultrasound was better for more proximal and cranial muscles than for muscles in the hand and lower limb. Needle EMG and muscle ultrasound typically produce disparate results and identify different aspects of muscle pathology. Muscle ultrasound seems less suited for detecting mild neurogenic abnormalities. As the severity of neurogenic needle EMG abnormalities increased, muscle ultrasound abnormalities were also increasingly found. Visual analysis seems better suited than grayscale quantification for detecting neurogenic abnormalities.

Could We Predict Respiratory Failure in Amyotrophic Lateral Sclerosis?

Introduction: Respiratory complications are important in the prognosis of amyotrophic lateral sclerosis (ALS). The aim of this study was to determine the electrophysiological findings that may predict respiratory failure. Methods: According to the Awaji electrodiagnostic criteria, 30 patients with ALS who were diagnosed with definite or probable ALS without respiratory failure were included in the study. Nerve conduction studies, needle electromyography (EMG), and single-breath count tests were performed in all patients. In addition, the pulmonary function tests, swallowing EMG, and arterial blood gas analysis of the patients were recorded and evaluated. The patients were followed until respiratory failure developed. Results: As a result of 18 months of follow-up, 26 of 30 patients developed respiratory failure. When the contribution of the accessory respiratory muscles to the respiratory effort before the development of respiratory failure was evaluated clinically and electrophysiologically, it was observed that the most common muscles involved in the respiratory effort were sternocleidomastoid (SCM), trapezius, and rectus abdominis. Before the development of respiratory failure, the latest neurogenic EMG findings were seen in the SCM (50% cases), trapezius (20% cases), and thoracic paraspinal muscles (17% of cases), respectively. It was thought that this finding could be an important early electrophysiologic marker in predicting the development of respiratory failure in ALS cases. Conclusions: To sum up, the presence of neurogenic changes in certain muscles in needle EMG and demonstration of the contribution of certain accessory respiratory muscles in respiration can be used as an electrophysiological marker to predict the development of respiratory failure.

Benign fasciculations: A follow-up study with electrophysiological studies.

Fasciculations can be symptomatic, yet not progress to amyotrophic lateral sclerosis (ALS), a condition categorized as benign fasciculation syndrome (BFS). We aimed to assess electrodiagnostic changes and clinical course over time in patients with BFS. This was a retrospective review of medical records of patients who were referred because of a suspicion of ALS or who had directly asked for a consultation because of a personal concern regarding ALS. All clinical and electromyography (EMG) investigations were performed by the same neurologist, following an established protocol. In addition, laboratory testing and imaging studies were performed as determined to be clinically necessary. We included 37 subjects (mean age 46 ± 14.7y, 29 male, 7 healthcare professionals). Most patients had experienced fasciculations in both upper and lower limb muscles (62.2%); the remaining patients had fasciculations only in their lower limbs. EMG in seven subjects showed chronic neurogenic potentials in addition to fasciculation potentials; all of these were older men. Follow-up data were available in 24 patients (median 4.7y), 21 with repeat EMGs, including all those with neurogenic EMG changes at baseline (median 6.5y). Two-thirds of patients reported symptomatic improvement: 57.1% of those with abnormal EMG and 61.1% with normal EMG. The EMG changes were stable. Prognosis of BFS is favorable, regardless of minor EMG abnormalities. The latter do not necessarily imply progression to ALS.

P78-F Can we predict respiratory failure in patients with Amyotrophic Lateral Sclerosis (ALS) electrophysiologically?

In ALS, respiratory complications are important in the prognosis of the disease. The aim of this study was to determine the electrophysiological findings that may predict respiratory failure. According to the Awaji electrodiagnostic criteria, 30 patients with ALS who were diagnosed as definite or probable ALS but without respiratory failure were included in the study. The patients were examined at intervals of 2–4 months. Neurological examination, nerve conduction studies, needle electromyography (EMG), pulmonary function test, electromyography of swallowing, arterial blood gas analysis and single breath count test were performed in all patients. Patients were followed until respiratory failure developed. One year follow-up, 17 patients developed respiratory distress. Neurological examinations and other tests were performed on average 3 times. The most sensitive finding that predicted respiratory failure was found to be neurogenic EMG recordings detected in sternocleidomastoid (SCM) muscle. It was observed that respiratory distress developed just after the participation of SCM and rectus abdominis muscles in the respiratory system. The reduction in the phrenic nerve compound muscle action potential amplitude is directly correlated to dyspnea, but its sensitivity is low. There is no sensitive biomarker predicting respiratory distress in patients with ALS. Although the number of cases in our study is not sufficient, neurogenic EMG findings in some muscles (such as SCM) and the participation of SCM and Rectus abdominis muscles to the respiration may be predictive for dyspnea. Although there are many studies related to ALS, there is no reliable test for early detection of respiratory failure. Further studies are needed.

Pathogenesis of cranial neuropathies in Moebius syndrome: Electrodiagnostic orofacial studies.

We designed a retrospective study of 59 patients with congenital sporadic nonprogressive bilateral facial and abducens palsies. Examinations included needle electromyography (EMG) of facial and oral muscles, facial nerve motor latency and conduction velocity (FNCV), and blink responses (BR). Neurogenic EMG changes were found in 1 or more muscles in 55 of 59 patients, with no abnormal spontaneous activity. EMG changes were homogeneously neurogenic in 17 patients, homogeneously myopathic in 1 patient, and heterogeneous in 41 of 59 patients. Motor latency was increased according to recordings from 52 of 137 facial muscles. An increase of motor latency was not associated with neurogenic EMG (Fischer's test: right, P = 1; left, P = 0.76). FNCV was slowed in 19 of 36 patients. BR was absent bilaterally in 35 of 58 patients; when present, R1 and R2 latencies were normal. Our results support the hypothesis of an early developmental defect localized in motor cranial nerves with spared V-VII internuclear pathways. Muscle Nerve, 2018.

Congenital multiple cranial neuropathies: Relevance of orofacial electromyography in infants.

The aim of this study was to assess diagnoses and outcomes of infants with 2 or more cranial neuropathies identified using orofacial electromyography (EMG). This retrospective study involved 90 patients. Diagnoses took into account clinical, radiological, and genetic data. EMG examined the orbicularis oculi, genioglossus, and levator veli palatini muscles, and blink responses. To evaluate outcome, neurological disability, respiratory complications, and feeding difficulties were recorded. The patients had malformation syndromes (59), encephalopathies (29), or no underlying disorders (2). Neurogenic EMG signs were detected in a mean of 4 muscles, reflecting a mean of 3 affected nerves. EMG identified a higher number of neuropathies than clinical examination alone (82 vs. 31, facial; 56 vs. 2, pharyngeal; 25 vs. 3, hypoglossal). Poor outcome and death were more frequent when EMG identified ≥4 affected nerves (P = 0.02). EMG highlights multiple cranial neuropathies that can be clinically silent in infants with malformation syndromes or encephalopathies.

Diagnostic Yield of Electromyography in Children With Myopathic Disorders

BackgroundInterpretation of pediatric electromyography interpretation in myopathic disorders is technically challenging. We assessed our electromyographic experience with respect to sensitivity and specificity in pediatric myopathy. MethodsWe did a retrospective chart review of patients ≤18 years between 2009 and 2013. Two hundred twenty-four electromyographic studies were reviewed with the following referral diagnoses: myopathy, muscle weakness, neuromuscular disorders, myositis, myalgia, myoglobinuria, myasthenia, myotonia, cramps, periodic paralysis, hypotonia, and developmental delay. Only children who had an electromyography and muscle biopsy were included for analysis. Patients with neurogenic electromyography and neuromuscular junction disorders were excluded. Myopathic electromyography was defined as short duration, low amplitude, polyphasic motor unit potentials with rapid recruitment. ResultsSeventy-two patients were included (age range, 6 months-18 years). The following observations were made: group A: myopathic electromyography or pathognomonic of muscle disease and biopsy or genetically confirmed myopathy (32 cases); group B: myopathic electromyography but biopsy normal or nondiagnostic (12 cases); group C: normal electromyography but biopsy or genetically confirmed myopathy (three cases, all with metabolic myopathy); and group D: electromyography normal and biopsy normal or nondiagnostic (25 cases). The most common diagnoses were congenital myopathy (seven cases), metabolic myopathy (six cases), muscular dystrophy (six cases), genetically confirmed myopathy (five cases), myopathy, undefined (five cases), and inflammatory myopathy (four cases). ConclusionsPediatric electromyography was 91% sensitive and 67% specific in myopathic disorders. The metabolic myopathies were commonly missed by electromyography.

Is peripheral neuron degeneration involved in multiple system atrophy? A clinical and electrophysiological study

Lower motor neuron lesions are not among the characteristic features of multiple system atrophy (MSA), although electromyography (EMG) and autopsy studies revealed peripheral neuron abnormalities in some cases of MSA.The aim of the study was to evaluate subclinical involvement of the peripheral neuron in MSA using EMG and electroneurography (ENG). Material48 patients with clinically probable MSA (mean age 60.6years; 67% males) were included in the study and divided into subgroups, with predominant cerebellar (MSA-C) and parkinsonian signs (MSA-P). MethodsENG in ulnar, peroneal and sural nerves and EMG of the first interosseus dorsal and tibial anterior muscles were performed. ResultsAbnormal ENG in one nerve was recorded in 20.8% of patients, and in two nerves in another 20.8% of patients. The most frequent and significant findings were decreased compound motor action potential amplitudes in the ulnar nerve in the overall MSA group as well as in the MSA-P type as compared to controls. Abnormalities suggesting reinnervation was observed in 43 of 96 examined muscles (44.7%). In individual cases, neurogenic features were recorded in one muscle in 31.2% of patients and in two muscles in 29.1% of patients. ConclusionsSubclinical axonopathy in MSA is not frequent and is more pronounced in MSA with predominant parkinsonian signs. In MSA, neurogenic EMG abnormalities in muscles are more frequent than peripheral nerve lesions and as evidenced by increased motor unit potential amplitudes, could be considered a sign of anterior horn cell involvement and a hallmark of the “continuum” of neurodegeneration in MSA.

Distal Symmetric Polyneuropathy in Diabetes. Differences between Patients with and without Neuropathic Pain

To demonstrate whether in distal symmetric polyneuropathy (DSPN) in diabetes there are differences between patients with and without neuropathic pain and whether pain is associated with demographic, clinical and electrophysiological variables. We prospectively enrolled 154 consecutive patients (mean age 67 years, 64% men) in an electromyography (EMG) lab. The differences were calculated between DSPN patients with (no.78) and without neuropathic pain (no.76) relating to age, sex, BMI, type, duration, treatment and complications of diabetes, HbA1c, type and duration of DSPN symptoms, DSPN clinical severity score (with Diabetic Neuropathic Index-DNI), electrophysiological findings of lower limb muscles and nerves. The differences between DSPN patients with and without pain included the presence of symptoms (burning and weakness), DNI score and neurographic findings of all nerves and neurogenic EMG. But in the logistic regression models enter only the following variables: DNI score, neurogenic EMG, and among symptoms "burning". The presence of pain in DSPN is associated with DSPN clinical severity, neurogenic EMG and presence of "burning- symptom but not with demographic or neurographic findings, or diabetes related variables. Therefore, the neuropathic pain in DSPN does not associate with the degree of involvement of large diameter sensory fibres or diabetes severity.

Upper trapezius electromyography aids in the early diagnosis of bulbar involvement in amyotrophic lateral sclerosis

Electromyography (EMG), particularly measurements of the tongue or sternocleidomastoid, aids in the diagnosis of amyotrophic lateral sclerosis (ALS) and may be used to identify lower motor neuron lesions in the bulbar region. Abnormal trapezius EMG recordings were recently shown to be useful in diagnosing ALS. Here, we investigated the role of upper trapezius EMG in assessing bulbar involvement in ALS. Standard EMG measurements were recorded from the upper trapezius in ALS, cervical spondylotic myelopathy (CSM), and normal controls (NC). Forty-three CSM patients were examined pre-operatively and three months post-operatively. Greater spontaneous activity levels were observed in upper trapezius EMG measurements of ALS patients with a disease duration of ≤8 months (70%), compared with patients with a disease duration of >8 months (40%). Significant differences in motor unit action potential parameters were also noted between ALS and CSM or NC. Fewer spontaneous EMG recordings were detected in CSM post-operatively. Furthermore, no differences in neurogenic EMG measurements were observed in ALS between the trapezius and sternocleidomastoid muscles (p = 0.22). In conclusion, upper trapezius EMG recordings may provide valuable information for assessing the clinical and subclinical involvement of bulbar lower motor neurons in ALS patients, particularly at early disease stages.

Spontaneous Incomplete Recovery of Peroneal Palsy After a Sealbite

Incomplete recovery of peroneal palsy, after a sealbite during swimming has not been reported. A 58-year-old woman was bitten into the right knee by a seal during swimming, resulting in incomplete division of the right profound branch of the peroneal nerve and complete division of the superficial branch of the peroneal nerve. Initial drop-foot, absent foot eversion, and hypaesthesia of the lateral lower leg were followed by almost complete clinical recovery of motor functions within four month by spontaneous re-innervation from the proximal nerve stump, despite severely abnormal electrophysiological findings. Re-evaluation 6 years after the accident revealed only discrete weakness for foot and toe extension, slight distal hypaesthesia, but still increased distal latency, reduced compound muscle action potential, slowed nerve conduction velocity of the right peroneal nerve, and neurogenic electromyography of the right anterior tibial and long peroneal muscles. Nerve conduction studies were hampered by co-innervation of the extensor digitorum brevis muscles by the tibial nerves. This case shows that peroneal palsy from a sealbite may recover spontaneously almost completely, but may go along with residual, subclinical, electrophysiological abnormalities. The later may be enhanced by innervation variants.

Electromyography (EMG) Accuracy Compared to Muscle Biopsy in Childhood

Reports show wide variability of electromyography (EMG) in detecting pediatric neuromuscular disorders. The study's aim was to determine EMG/nerve conduction study accuracy compared to muscle biopsy and final clinical diagnosis, and sensitivity for myopathic motor unit potential detection in childhood. Of 550 EMG/nerve conduction studies performed by the same examiner from a pediatric neuromuscular service, 27 children (ages 6 days to 16 years [10 boys; M:F, 1:1.7]) with muscle biopsies and final clinical diagnoses were compared retrospectively. Final clinical diagnoses were congenital myopathies (5 of 27,18%), nonspecific myopathies (biopsy myopathic, final diagnosis uncertain; 6 of 27, 22%), congenital myasthenic syndrome (3 of 27, 11%), juvenile myasthenia gravis (1 of 27, 4%), arthrogryposis multiplex congenita (2 of 27, 7%), hereditary motor and sensory neuropathy (1 of 27, 4%), bilateral peroneal neuropathies (1 of 27, 4%), and normal (8 of 27, 30%). There were no muscular dystrophy or spinal muscular atrophy patients. EMG/nerve conduction studies had a 74% agreement with final clinical diagnoses and 100% agreement in neurogenic, neuromuscular junction, and normal categories. Muscle biopsies concurred with final diagnoses in 87%, and 100% in myopathic and normal categories. In congenital myasthenic syndrome, muscle biopsies showed mild variation in fiber size in 2 of 3 children and were normal in 1 of 3. EMG sensitivity for detecting myopathic motor unit potentials in myopathies was 4 of 11 (36%), greater over 2 years of age (3 of 4, 75%), compared to infants less than 2 years (1 of 7, 14%), not statistically significant (P = .0879). EMGs false-negative for myopathy in infants < 2 years of age were frequently neurogenic (3 of 6, 50%). In congenital myopathies EMG detected myopathic motor unit potentials in 40%, with false-negative results neurogenic (20%) or normal (40%). Because our study has no additional tests for active myopathies, for example Duchenne muscular dystrophy genetic testing, our sensitivity for myopathies is lower than if we used a more global view. In conclusion, EMG detection rate of myopathic motor unit potentials at a young age was low, improving in children over 2 years of age. In neurogenic and neuromuscular junction disorders, the EMG has a very high detection rate. In children with mild to moderate neurogenic EMG findings and normal nerve conduction, a myopathy should always be considered.

Lower urinary tract dysfunction in Machado–Joseph disease: a study of 11 clinical-urodynamic observations

Objectives: Machado–Joseph disease (MJD), or hereditary spinocerebellar ataxia type 3, is the most common dominantly inherited ataxia. However, lower urinary tract (LUT) dysfunction in MJD has not been fully delineated. We investigated LUT dysfunction in MJD by clinical-urodynamic observations. Methods: In 24 genetically diagnosed MJD, we recruited all 11 patients with LUT symptoms (six men, five women; age, 18–61 [mean 48] years; disease duration, 2–24 [mean 9] years; voiding difficulty, 7, urinary incontinence, 4). Urodynamic studies consisted of uroflowmetry, measurement of post-void residuals and electromyography (EMG)-cystometry. Neurophysiology tests consisted of motor unit potential (MUP) analysis of the sphincter and extremity muscles, tibial nerve somatosensory evoked potentials (SEP) and nerve conduction studies (NCS) of the extremities. Results: Urodynamic abnormalities were seen in all 11 patients studied. Maximum or average flow rate was decreased in five. Post-void residual was noted in three but residual urine volume >100 ml was noted in only one patient. Maximum urethral closure pressure was low in one and high in one of five patients studied. EMG-cystometry during filling showed detrusor overactivity in five, impaired bladder sensation in four, low compliance detrusor in one, uninhibited sphincter relaxation in one and incompetent urethra in one. Voiding phase abnormalities included detrusor areflexia in three and detrusor-sphincter dyssynergia in two. Bethanechol supersensitivity of the bladder was noted in one of three patients studied. Bulbocavernosus reflex was absent in two of five patients studied. MUP analysis showed neurogenic changes in six of nine sphincter muscles and in all six extremity muscles studied. Five patients had prolonged or absent cortical response in SEP and four had sensory axonal neuropathy in NCS, which were relevant to the impaired bladder sensation. Conclusion: In the present study, a half of MJD patients had LUT symptoms and they showed various urodynamic abnormalities. Detrusor overactivity, impaired bladder sensation, and neurogenic sphincter EMG were common findings, and large post-void residuals were rare. These findings are relevant to central and peripheral nervous system pathology of MJD.

Neurophysiological findings in women with recurrent urinary incontinence after Burch colposuspension

The aim of this prospective observational study was to analyze the occurrence of neurogenic damage in the pelvic floor muscles in women with recurrent stress urinary incontinence, and to analyze whether a peripheral neuropathy in general covariates with possible neurogenic damage to the pelvic floor muscles. Seventeen women with recurrent stress urinary incontinence and 16 healthy continent women underwent a concentric needle electromyography (EMG) of the pubococcygeal muscles bilaterally and the external anal sphincter muscle, and a neurography of eight peripheral nerves. Seventy-five per cent of the healthy continent women displayed a deviant neurogenic pattern of the EMG in at least one of the pubococcygeal muscles, compared to 76% of the women with recurrent incontinence. Neurogenic patterns in all three investigated muscles were found significantly more often among the women with recurrent incontinence than in the healthy continent women. The age of all the women with neurogenic EMG patterns in all three muscles investigated was significantly higher than that of the women with neurogenic EMG patterns in two or less of the investigated muscles. The neurographic measurements showed no statistically significant differences between the groups. Conclusions showed that a neurogenic EMG pattern was frequently observed in the pubococcygeal muscles. Women with recurrent stress urinary incontinence were found to exhibit deviant EMG patterns in more pelvic floor muscles than did continent women.

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.