Needle Electromyography Findings Research Articles

Atypical Facio-Scapulo-Humeral Dystrophy with facial sparing: a case report

Facio-Scapulo-Humeral Dystrophy (FSHD) is an autosomal dominant and third most common inherited muscular dystrophy. Typical phenotype of FSHD initially affects the muscles of the face and upper arm. Atypical FSHD refers to genetically confirmed FSHD with phenotypic variations. Scapulo-Humeral Dystrophy (SHD) is the most common atypical form of FSDH characterized by no facial muscle weakness on clinical examination, while other signs remain consistent with FSHD. We report a 31-year-old male who presented with foot drop and had an unexpected presentation as SHD. Provisional diagnosis of SHD was based on careful medical history, physical examination findings, modest rise in muscle enzymes, and needle electromyography findings of myopathy. Muscle biopsy suggested dystrophic changes which supported the diagnosis of FSHD with facial sparing. Rehabilitation plan included patient and family counseling/education, lifestyle modifications, energy conservation strategies, right ankle foot orthosis, and therapeutic exercises with regular follow-up for monitoring of the disease.

Chapter 3 - The role of electrodiagnosis in focal neuropathies

Electrodiagnostic (EDX) testing plays an important role in confirming a mononeuropathy, localizing the site of nerve injury, defining the pathophysiology, and assessing the severity and prognosis. The combination of nerve conduction studies (NCS) and needle electromyography findings provides the necessary information to fully assess a nerve. The pattern of NCS abnormalities reflects the underlying pathophysiology, with focal slowing or conduction block in neuropraxic injuries and reduced amplitudes in axonotmetic injuries. Needle electromyography findings, including spontaneous activity and voluntary motor unit potential changes, complement the NCS findings and further characterize chronicity and degree of axon loss and reinnervation. EDX is used as an objective marker to follow the progression of a mononeuropathy over time.

Optimization of Muscle Selection for Needle Electromyography in Isolated C6 Root Lesion: A Prospective Chart Review Study.

The aim of the study is to evaluate muscles with more prominent needle electromyographic findings to optimize needle electromyography screening of isolated C6 radiculopathy in patients with C6 root lesions. This prospective clinical study was performed on 39 patients with isolated and unilateral cervical radiculopathy selected from all referrals of 1733 patients to the electrodiagnosis unit of the physical medicine and rehabilitation department of a tertiary medical center (from April 2021 to December 2021). The presence of fibrillation potentials, positive sharp waves, and/or neurogenic motor action potentials that occurred in isolation or combination with selected muscles was considered an abnormal finding. Of 1733 referrals, 39 patients (18 males [46.1%] and 21 females [53.8%]), with a mean age of 49.7 ± 9.6 yrs, were found eligible. According to needle electromyography findings, the most involved muscles in C6 root lesion were pronator teres (100%), followed by extensor carpi radialis longus (94.8%), flexor carpi radialis (89.7%), brachioradialis (82%), infraspinatus (82%), supraspinatus (79.4%), deltoid (74.3%), biceps brachii (64.1%), extensor digitorum communis (33.3%), and triceps brachii (15.3%) muscles. The pronator teres is the most involved muscle of patients diagnosed with C6 radiculopathy. It might be considered the key muscle for screening and accurate diagnosis of C6 root involvement.

Changes in electrophysiological findings of spinal muscular atrophy type I after the administration of nusinersen and onasemnogene abeparvovec: two case reports

BackgroundRecently, there have been significant advances in the treatment of spinal muscular atrophy (SMA). Although clinical improvement in patients with SMA after the treatment has been reported, changes in electrophysiological findings, especially needle electromyography (EMG), have rarely been reported. Herein, we report the posttreatment changes in EMG and nerve conduction study findings over time in two patients with SMA type I.Case presentationPatient 1: A 2.5-year-old girl was diagnosed with SMA type I at 1 month of age. She received nusinersen four times and onasemnogene abeparvovec (OA) was administered at 6 months of age. The compound muscle action potential (CMAP) amplitudes of the median and tibial nerves increased over time. The needle EMG after the treatment showed high-amplitude motor unit potentials (MUPs) suggestive of reinnervation during voluntary contraction, which were not seen before the treatment. However, fibrillation potentials at rest were still seen after the treatment. Patient 2: A 2-year-old girl was diagnosed with SMA type I at 6 months of age. She had received nusinersen two times and OA was administered at 7 months of age. The CMAP amplitudes and the MUPs presented similar changes as presented in Case 1.ConclusionThis is the first report on the changes in needle EMG findings after treatment in patients with SMA type I. These findings suggested that peripheral nerve reinnervation occurred after the treatment, although active denervation was still present. The accumulation of these findings will be important for evaluating the effectiveness of treatment for SMA in the future.

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.

Concordance between needle electromyography and manual muscle test findings for muscles with motor grades 0 and 1.

When it is difficult to determine whether a muscle is grade 0 or 1, manual muscle test (MMT) accuracy can be further improved by using needle electromyography (EMG) as a supplementary and confirmatory examination tool. To evaluate concordance between needle EMG and MMT findings for key muscles with motor grades 0 and 1 on the International Standards of Neurological Classification of Spinal Cord Injury (ISNCSCI) examination, and to potentially improve the prognosis for grade 0 muscles with proven muscle activity based on needle EMG findings. A retrospective analysis. Inpatient tertiary rehabilitation facility. Not applicable. One hundred seven patients with spinal cord injury (SCI) admitted for rehabilitation (n = 1218 key muscles, grades 0 or 1). Inter-rater reliability between MMTs and needle EMG was analyzed using Cohen's kappa coefficient (κ). A Mantel Haenszel linear-by-linear association chi-square testwas used to determine whether the presence of motor unit action potentials (MUAPs) in muscles graded 0 on the initial MMT at admission was associated with MMT grades at discharge and readmission. Moderate-to-substantial agreement between needle EMG and MMT findings was observed (κ = 0.671, p < .01). Concerning key upper and lower extremity muscles, moderate and substantial agreement was identified, respectively. The lowest agreement was noted for C6 muscles. During follow up, 68.8% of muscles with proven MUAPs showed improved motor grades. At initial assessment, distinguishing between motor grades 0 and 1 is imperative because motor grade 1 muscles are more likely to have a better prognosis for improvement. Moderate-to-substantial agreement was observed between MMT and needle EMG findings. The MMT is a reliable method of muscle grading, yet needle EMG may be of value in certain clinical situations to evaluate for the presence of MUAPs when evaluating motor function.

Needle electromyography abnormalities in the upper trapezius muscle in neuromuscular disorders.

: Needle electromyography (EMG) abnormalities in the trapezius muscle (TM) can be seen in neuromuscular disorders. The aim was to determine the characteristics of needle EMG abnormalities observed in the TM in neuromuscular disorders. The data of patients who applied to the Clinical Neurophysiology Laboratory of University of Health Sciences Adana City Training and Research Hospital between December 2018 and October 2021 were reviewed. Polio survivors, amyotrophic lateral sclerosis (ALS) patients, patients with sensorimotor polyneuropathy, patients with spinal cord lesions involving C2/C3/C4 segments, patients with spinal accessory nerve (SAN) lesions, neuralgic amyotrophy (NA) patients, and patients with myopathy were included. Needle EMG findings of the upper TM of the patients were analyzed. Positive sharp waves, fibrillation potentials, fasciculation potentials, myotonic discharges, and motor unit action potential (MUAP) changes were considered needle EMG abnormalities. Eighty-one polio survivors, 23 ALS patients, 39 patients with sensorimotor polyneuropathy, 10 patients with cervical spinal lesions, eight NA patients, seven patients with SAN lesions, and three patients with myopathy were included in the study. Fifteen (65.2%) ALS patients, 18 (22.2%) polio survivors, three (30%) patients with cervical spinal lesions, two (5.1%) patients with sensorimotor neuropathy, one (12.5%) NA patient, seven (100%) patients with SAN lesions, and two (66.7%) patients with myopathies had at least one needle EMG abnormality in the TM. Fasciculation potentials in the TM were seen in 10 (43.5%) ALS patients. In four patients with SAN lesions and one polio survivor, MUAP could not be obtained from the TM. There may be more frequent needle EMG abnormalities, particularly in ALS patients and patients with SAN lesions. Since the number of patients with myopathy included in this study was low, it is difficult to comment on the needle EMG features of the TM for these patients. In addition, this study indicated that fasciculation potentials in the TM are typical in ALS patients and that MUAP may not be obtained from the TM in patients with SAN lesions.

Electrodiagnostic Features of Sciatic Neuropathy: Six-year Referral Center Experience

ABSTRACT Introduction: Sciatic neuropathy is one of the most important neuropathies of the lower extremity. Although electromyography (EMG) is useful for detecting and localizing neurologic damage, assessing the severity of neuropathy, determining prognoses, and detecting confounding or accompanying neurologic pathologies, electrodiagnostic analyses of sciatic neuropathy are rare in the literature. Methods: The EMG database between 2017 and 2022 was reviewed. Neurophysiologic data of 58 patients who were electrophysiologically diagnosed as having sciatic neuropathy were included in the study. The adult patient group was divided into three groups, injection trauma, noninjection trauma, and other etiologies for subgroup analyze. Pediatric patients were not divided into subgroups because of their limited number. Results: Sciatic neuropathy was found in nine patients in the pediatric group, and 48 patients in the adult group. Sciatic neuropathy was left sided in six (66.7%) pediatric patients and 25 (52%) adult patients. It was bilateral in one adult patient. There was no significant difference between the groups in terms of nerve conduction studies. No statistically significant difference was found in the needle EMG of the gastrocnemius medialis, tibialis anterior (TA), and biceps femoris short-head muscles (P = 0.78, P = 0.32, and P = 0.14, respectively). In both injection and noninjection trauma patients, the most common needle EMG findings in the gastrocnemius medialis muscle were detected as grade 2. Grades 3 and 4 findings were observed predominantly in peroneal division innervated TA and biceps femoris short-head muscles. Conclusion: The most common etiology of sciatic neuropathy in adults was injection-related trauma. The peroneal division is more prone to injury in sciatic neuropathy in the context of sciatic variations. Consequently, we considered that the degree of damage in noninjection traumas might be higher in both distal and proximal segments compared with injection traumas.

Positive sharp waves and fibrillation potentials in polio survivors with sequelae: Are they due to late deterioration or radiculopathy?

Background &amp; Objective: Needle electromyography (EMG) abnormalities can be observed in clinically affected or unaffected muscles in polio survivors. The primary aim of this study is to evaluate the positive sharp waves (PSWs) and fibrillation potentials (FPs) that can be observed in polio survivors. In addition, the presence of post-polio syndrome and radiculopathy was investigated in patients with PSWs/FPs. Methods: Clinical features and needle EMG findings of polio survivors with sequelae who applied to our neurophysiology laboratory between August 2018 and January 2021 were analyzed retrospectively. Cervical and lumbosacral magnetic resonance imaging (MRI) of polio survivors with PSWs/FPs were included in the analyses. In addition, polio survivors were divided into groups with and without post-polio syndrome. Results: Fifty-one polio survivors (33 male, 18 female) were included in the study. The mean age of the patients was 49.5±7.5 years. There were 13 (25.5%) polio survivors with post-polio syndrome. Needle EMG findings of 590 muscles were analyzed. PSWs/ FPs were found in 11 medial gastrocnemius, four iliopsoas, four tibialis anterior, two vastus lateralis muscles, and one deltoid muscle. PSWs or FPs were present in 12 (23.5%) of patients. PSWs/FPs were present in three (23.1%) and nine (23.7%) polio survivors with and without post-polio syndrome, respectively (p&gt;0.05). Of the 12 patients with PSWs/FPs, 11 had cervical and lumbosacral MRIs. In eight (72.7%) of these 11 patients with PSWs/FPs, the nerve segment of the muscle with PSWs/FPs and the segment of radiculopathy detected by MRI were compatible with each other. Conclusions: This study indicated that PSWs/FPs may be present in polio survivors. PSWs/FPs may be due to radiculopathy and/or late deterioration. It was concluded that PSWs/FPs are not a parameter that can be used to differentiate polio survivors with and without post-polio syndrome.

Concordance between the international standards for neurological classification of spinal cord injury motor examination and needle electromyography findings in muscles with a motor power grade of zero or trace

Context/Objective To evaluate the accuracy of the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) motor examination in individuals with spinal cord injury (SCI) with motor grade 0 or 1 and analyze its degree of concordance with needle electromyography (EMG) findings for each key muscle. Design Retrospective study. Setting University hospital in Goyang, Korea. Participants Individuals with SCI admitted to the Department of Rehabilitation from January 2013 to June 2019. Interventions In the enrolled persons, needle EMG was performed on muscles with motor grade 0 or 1 on ISNCSCI examination, and muscle contraction was confirmed through the detection of motor unit action potential. Outcome measures The agreement between motor examination and needle EMG findings was analyzed. Results In 175 key muscles, needle EMG findings in 115 and 60 muscles evaluated as grades 0 and 1 on ISNCSCI examination showed 80% and 50% agreements, respectively. We found a fair agreement between motor examination and needle EMG findings (κ = 0.309, P < 0.0001). Moreover, statistically significant agreement was seen only in T1, L2, and S1 key muscles (κ = 1, P < 0.0001; κ = 0.359, P = 0.019; and κ = 0.521, P = 0.004, respectively). Conclusions It is important to accurately distinguish between grade 0 and 1 motor power to maximize the positive outcomes from rehabilitation treatment and predict the possibility of recovery in individuals with SCI. Therefore, to improve the accuracy of motor examination and the American Spinal Injury Association Impairment Scale, needle EMG confirmation could be considered for muscles with motor grade 0 or 1 in individuals with SCI.

Relevant muscle selection for needle electromyography examination in polio survivors

Objectives: Needle electromyography (EMG) has an important role in the diagnosis of poliomyelitis. Since needle EMG is a painful and time consuming procedure, selecting the most effective muscles for needle EMG is important. We aimed to determine the clinically or subclinically affected regions in polio survivors by examining the minimum number of muscles with EMG. Methods: Polio survivors with weakness in at least one limb were included in this retrospective cohort study. The extremities were divided into two groups: 1) Group 1: The extremities with Medical Research Council score of ≤ 1 in at least one muscle, 2) Group 2: Clinically unaffected or mildly to moderately affected extremities that do not meet the criteria of Group 1. The needle EMG findings of the muscles were analyzed. Results: Twenty-nine polio survivors were included in the study. Needle EMG findings of 352 muscles were reviewed. Needle EMG findings in 57 lower extremities and thirty-two upper extremities were analyzed. There was no upper extremity meeting the criteria of Group 1. Thirty-eight lower extremities were included in Group 1. The amplitudes and durations of motor unit action potentials (MUAPs) were not different between the muscles of the Group 1 lower extremities (p &amp;gt; 0.05). Among the muscles of Group 2 upper and lower extremities, the amplitude and duration of MUAPs were higher in the deltoid and the vastus lateralis muscles compared to the other muscles, respectively (p = 0.002 and p = 0.003 for upper extremity muscles; p = 0.005 and p &amp;lt; 0.001 for lower extremity muscles). Conclusions: Using the needle EMG findings, an algorithm was made to determine the affected regions. Thus, the affected regions can be identified by applying needle EMG to a minimum number of muscles.

The needle electromyography findings in the neurophysiological classification of ulnar neuropathy at the elbow

Background/aimAlthough ulnar neuropathy at the elbow (UNE) is the second most common entrapment mononeuropathy, there are few reports on its neurophysiological classification. In this study, we tried to find out the role of needle electromyography (EMG) in the neurophysiological classification of UNE.Materials and methodsUNE patients who met the clinical and neurophysiological diagnostic criteria and healthy individuals were included in this study. Reference values of nerve conduction studies were obtained from healthy individuals. Needle EMG was performed to all UNE patients. According to the neurophysiological classification proposed by Padua, UNE patients were classified as mild, moderate, and severe.ResultsThirty-one controls and thirty-five UNE patients were included in the study. There was mild UNE in 23 patients, moderate UNE in 8, and severe UNE in 4. Abnormal needle EMG findings were present in all patients with moderate and severe UNE and in 12 patients with mild UNE. ConclusionAbnormal needle EMG findings are seen in most of the UNE patients. Therefore, it is not practical to use needle EMG findings in the neurophysiological classification. Needle EMG abnormalities may also be present in patients with mild UNE due to axonal degeneration or motor conduction block.

Needle electromyography, muscle MRI, and muscle pathology: Correlations in idiopathic inflammatory myopathies

AbstractBackgroundOn needle electromyography (EMG), abnormal spontaneous activity is considered a feature of active myositis. However, the correlation between needle EMG and muscle pathology is not always clear. Moreover, the changes in EMG findings after corticosteroid therapy are not fully understood.AimTo investigate the correlations among muscle pathology, needle EMG and muscle MRI findings in patients with idiopathic inflammatory myopathies (IIMs).MethodsThe clinical features, laboratory results, needle EMG, muscle MRI findings and pathological features of 50 consecutive patients with IIMs who underwent muscle biopsies were reviewed. We also describe the changes in these findings between before and after corticosteroid treatments.ResultsThe most common IIM was dermatomyositis (40%). On needle EMG, fibrillation/positive sharp waves (Fib/PSWs) were observed in 72% of the patients. MRI abnormalities were observed in 86% of the patients. In the pathology study, 88% of patients had inflammatory markers. The incidence of Fib/PSWs did not differ between pretreatment patients (79%) and steroid‐treated patients (62%). In the pathology study, perimysium/perivascular cell infiltration also did not differ between before and after treatment. However, endomysium cell infiltration was significantly less frequent in steroid‐treated patients (0%) than in pretreatment patients (29%) (P &lt; .05).ConclusionsOur study confirmed that Fib/PSWs on needle EMG and muscle MRI were sensitive guides for diagnosing IIMs, and Fib/PSWs might be correlated with muscle fiber injuries or segmental necrosis rather than inflammatory cell infiltration in the affected muscles. Before treatment and within at least 1 month after starting corticosteroid treatment, Fib/PSWs could be detected by needle EMG.

Pattern of muscle involvement according to needle electromyography findings in clinically unaffected extremities of polio survivors with lower extremity weaknesses

Amac: Paralitik poliomiyelit oykusu olan hastalarda gec donem noromuskuler kotulesme gorulebilir. Bu sorunlardan birisi, klinik olarak etkilenmemis kaslarda yeni bir gucsuzlugun gelisimidir. Bu klinik olarak etkilenmemis ekstremite kaslarindaki igne elektromyografi (EMG) bulgularini saptamayi ve poliomiyelitin fizik tedavi stratejilerine katkida bulunmayi amacladik. Yontemler: Poliomiyelit sekeli olan hastalar bu retrospektif kohort calismasina calismaya dahil edildi. Hastalarin igne EMG bulgulari gozden gecirildi. Gucsuzlugu olmayan ekstremite veya kasta norojenik igne EMG bulgulari varsa, bu kas veya ekstremite subklinik olarak etkilenmis olarak kabul edildi. Bulgular: Onsekiz hasta calismaya dahil edildi. Yuzdoksan kasin igne EMG bulgulari analiz edildi. Alt ekstremitelerde, klinik olarak etkilenmeyen 25 kasin 18'inde (%72) norojenik igne EMG bulgulari vardi, 40 ust ekstremite kasinin 14’unde (%35) subklinik tutulum mevcuttu. Alt ekstremite kaslarindaki bu subklinik tutulum, ust ekstremite kaslarina gore anlamli olarak daha fazla orandaydi (P=0,004). Klinik olarak etkilenmemis ust ve alt ekstremite kaslari icinde, en belirgin norojenik igne EMG bulgulari sirasiyla deltoid ve vastus lateralis kaslarinda idi (sirasiyla; P=0,022 ve P=0,028). Sonuc: Alt ekstremite gucsuzlugu olan polio hastalarinda subklinik tutulum alt ekstremitede ust ekstremiteden daha belirgindi. Alt ve ust ekstremitelerde en belirgin subklinik kas tutulumu sirasiyla vastus lateralis ve deltoid kaslarindaydi. Bu bulgulari dikkate alan fizik tedavi stratejilerinin polio hastalari icin faydali olacagini dusunuyoruz.

Needle electromyography and histopathologic correlation in myopathies.

Needle electromyography (EMG) findings help confirm myopathy and may indicate specific pathologic changes on muscle biopsy. We conducted a retrospective chart review of 218 consecutive patients referred for muscle biopsy. Presence of specific needle EMG findings was correlated with pathologic findings of inflammation, necrosis, splitting, and vacuolar changes. Sensitivity, specificity, and positive and negative predictive values of specific EMG findings for pathologic changes were calculated. Short-duration motor unit potentials (MUP) were sensitive (83%-94%) but not specific (34%-49%) for pathologic changes. Fibrillation potentials were 65%-74% sensitive and 58%-81% specific for inflammation, necrosis, splitting, or vacuolar changes. The absence of fibrillation potentials had high negative predictive value (82%-93%) for inflammation, splitting, or vacuolar changes. Fibrillation potentials and short-duration MUPs predict pathologic changes of muscle fiber necrosis, splitting, and/or vacuolar changes (as seen with inflammatory myopathies and muscular dystrophies). Absence of fibrillation potentials suggests other myopathologic changes (e.g., congenital myopathy). Muscle Nerve 59:315-320, 2019.

Electromyographic study to predict functional outcome of transforaminal epidural steroid injection in lumbosacral radiculopathy

ContextEpidural steriod injections (ESIs) are commonly used for managment of lumbosacral radiculopathy (LSR). Predicting outcomes after ESIs could be another valuable application of needle electromyography (EMG) in these patients.AimThe aim was to determine if EMG study can predict the functional outcome of transforaminal ESIs in patients with LSR.Materials and methodsThe study included 20 patients with clinical diagnosis of LSR. Peripheral nerve conduction study, late responses, somatomsensory evoked potentials, and needle EMG were performed in both lower limbs followed by transforaminal ESI under fluoroscopic guidance. The functional outcome was evaluated using visual analog scale for pain and Oswestry disability index (ODI) that were performed before and after injections.ResultsThere were statistically significant decrease in pain severity (visual analog scale; P=0.022) and in ODI (improvement in functional score; P=0.029) after injection in patients with symptom duration less than 3 months compared with patients with longer duration of symptoms. In patients with negative EMG findings, there was a significantly greater reduction in pain severity (P<0.01) and ODI score (P<0.01) after injection compared with patients with positive findings. Regression analysis showed that negative needle EMG findings were significant predictors of pain reduction (P=0.001) and functional improvement (P=0.002) in patients with LSR after ESI.ConclusionThis study supports the notion that EMG studies can be used for prediction of functional outcome in patients with LSR performing transforaminal ESI.

Somatotopic Fascicular Lesions of the Brachial Plexus Demonstrated by High-Resolution Magnetic Resonance Neurography.

The aim of this study was to evaluate whether high-resolution brachial plexus (BP) magnetic resonance neurography (MRN) is capable of (1) distinguishing patients with compressive neuropathy or noncompressive plexopathy from age- and sex-matched controls, (2) discriminating between patients with compressive neuropathy and noncompressive plexopathy, and (3) detecting spatial lesion patterns suggesting somatotopic organization of the BP. Thirty-six patients (50.9 ± 12.7 years) with clinical symptoms, nerve conduction studies, and needle electromyography findings suggestive of brachial plexopathy and 36 control subjects matched for age and sex (50.8 ± 12.6 years) underwent high-resolution MRN of the BP. Lesion determination and localization was performed by 2 blinded neuroradiologists at the anatomical levels of the plexus trunks and cords. By applying defined criteria of structural plexus lesions on high-resolution MRN, all patients were correctly rated as affected, whereas 34 of 36 controls were correctly rated as unaffected by independent and blinded reading from 2 neuroradiologists with overall good to excellent interrater reliability. In all cases, plexopathies with a compressive etiology (n = 12) were correctly distinguished from noncompressive plexopathies with inflammatory origin (n = 24). Pathoanatomical contiguity of lesion from trunk into cord level allowed recognition of distinct somatotopical patterns of fascicular involvement, which correlated closely with the spatial distribution of clinical symptoms and electrophysiological data. Brachial plexus MRN is highly accurate for differentiating patients with symptomatic plexopathy from healthy controls and for distinguishing patients with compressive neuropathy and noncompressive plexopathy. Furthermore, BP MRN revealed evidence for somatotopic organization of the BP. Therefore, as an addition to functional information of electrodiagnostic studies, anatomical information gained by BP MRN may help to improve the efficiency and accuracy of patient care.

The relationship between preoperative needle electromyography findings and muscle power restoration after surgery in severe carpal tunnel syndrome patients.

Needle electromyography provides essential information about the functional aspects of the muscle. But little attention has been given in the literature to needle electromyography examinations in carpal tunnel syndrome. We examined the relationship between preoperative needle electromyography findings and functional recovery of the abductor pollicis brevis (APB) muscle in severe carpal tunnel syndrome patients. The subjects of this study were 49 patients, 58 hands, who fit the following 5 criteria: (1) idiopathic carpal tunnel syndrome; (2) pre-op MMT grade of the APB muscle was M0 or M1; (3) APB-CMAP (compound muscle action potential) was not evoked in a median nerve conduction study; (4) needle electromyography of the APB muscle had been done; (5) underwent carpal tunnel release only. The patients were divided into two groups according to the results of pre-op needle electromyography: voluntary motor unit potential of the APB muscle was evoked [MUP(+) group]or not [MUP(-) group]. We evaluated APB muscle strength at one year after surgery, and patient satisfaction and functional evaluations (CTSI-FS) at more than one year after. The APB muscle recovery rate to M3 or higher was 100% in the MUP(+) group, and 57% in the MUP(-) group. Patient satisfaction was also high and functional recovery was sufficient in the MUP(+) group. No patients requested a second opponensplasty. Our findings suggest that post-op restoration of thumb function relates to whether or not the MUP ofthe APB muscle is evoked. Single-stage opponensplasty may be unnecessary if the MUP of the APB muscle is; evoked. Needle electromyography is therefore useful in consideration for opponensplasty. Level Ⅲ, case-control study.

Pseudomyopathic Changes in Needle Electromyography in Lambert-Eaton Myasthenic Syndrome

Lambert-Eaton myasthenic syndrome (LEMS) is a rare presynaptic disorder of the neuromuscular junction in association with cancer and subsequently in cases in which no neoplasm has been detected (O'Neill et al., 1988). The diagnosis of LEMS is based on the combination of fluctuating muscle weakness, diminished or absent reflexes, and a more than 60% increment of compound muscle action potential (CMAP) amplitude after brief exercise or 50 Hz stimulation for 1 s in a repetitive nerve stimulation (RNS) test (Oh et al., 2005). On the other hand, needle electromyography (EMG) findings related to LEMS have not been well described. Here, we report a case of LEMS, which showed apparent myopathic changes in needle EMG findings. Furthermore, we retrospectively examined the needle EMG findings in 8 patients with LEMS. In six of the 8 patients, the EMG findings showed myopathy-like findings. Although the findings of needle EMG indicated myopathic changes at a glance, the motor unit potential (MUP) returned to normal after a sustained strong muscle contraction. We propose the name “pseudomyopathic changes” for this phenomenon.

171. A case of myofibrillary myopathy associated with rigid spine syndrome

Introduction: This is a case of an 11-month-old Cambodian boy, third child born to nonconsanguionous parents, who was previously well. He developed an acute onset of respiratory distress with lethargy following an upper respiratory illness, requiring intubation and ventilatory support. At presentation, he was noted to have marked spine and abdominal muscle rigidity with mild peripheral hypotonia of his limbs. He was initially treated empirically for meningoencephalitis and subsequently tetanus with no improvement of his symptoms. Objectives: To describe the clinical presentation of myofibrillar myopathy. Results: Brain magnetic resonance imaging was normal. His serum creatine kinase was mildly raised at 1000. Echocardiography showed mild septal hypertrophy of the heart. Needle electromyography (EMG) showed myopathic features and his muscle biopsy showed the presence of eosinophilic hyaline bodies on hematoxylin and eosin staining with suggestion of inter-myofibrillary disruption on modified Gomori-Trichrome and Verhoff-Van Gieson stains. He remained dependent on ventilator support and underwent a tracheostomy during his admission. Conclusion: This is a case of myofibrillar myopathy associated with rigid spine syndrome, respiratory insufficiency, and mild cardiomyopathy. Diagnosis was made with muscle biopsy and needle EMG findings.