Needle EMG Research Articles

Human cremaster muscle and cremasteric reflex: A comprehensive review

ObjectiveHuman research on the cremaster muscle (CM), cremasteric reflex (CMR) and genitofemoral nerve (GFN) and reports on their clinical applications using electrophysiological and histological techniques are rare. We aimed to present a detailed review of the human CM and CMR based on our earlier publications and relevant literature. MethodsElectromyography (EMG) of the CM was recorded using disposable needle electrodes. CMR was obtained with tactile and/or electrical stimulation of the inner thigh. Transcranial magnetic stimulation (TMS) and magnetic stimulation of the upper lumbar roots were applied; GFN was stimulated using a surface electrode at the anterior superior iliac spine. ResultsCM striated fibers comprised multiple motor end plates. CM needle EMG results were similar to those of the limb muscles in chronic neurogenic disorders. TMS produced clear-cut evoked motor responses from CM. GFN motor conduction time to CM was absent or delayed in patients with inguinal hernia. EMG of CM was abnormal in 40% of patients with premature ejaculation. ConclusionCM is different from other skeletal muscles both morphologically and physiologically. Intersegmental sacrolumbar reflexes are useful for evaluating ejaculatory dysfunction. SignificanceCM is an important muscle for testis thermoregulation and sexual reflexes. Neurophysiological techniques are available for physiological and clinical studies.

Are There Trigger Points in the Spastic Muscles? Electromyographical Evidence of Dry Needling Effects on Spastic Finger Flexors in Chronic Stroke.

The purpose was to examine the immediate effects of dry needling to spastic finger muscles in chronic stroke. Ten chronic stroke patients with spasticity in finger flexors participated in this experiment. Dry needling to the flexor digitorum superficialis (FDS) muscle was performed under ultrasound guidance for about 30 s (about 100 times). Clinical assessment and intramuscular needle EMG readings were made before and immediately after dry needling. Immediately after needling, the FDS muscle was felt less tight to palpation and the proximal phalangeal joint rested in a less flexed position (p = 0.036). The MAS score decreased for FDS (p = 0.017) and flexor digitorum profundus (FDP) (p = 0.029). Motor unit action potential (MUAP) spikes decreased from 41.6 ± 5.5 to 6.7 ± 2.2 spikes/s (p = 0.002), an 84% reduction after dry needling. However, the pre-needling spike frequency was not correlated to MAS or resting position of the FDS muscles. Dry needling to the spastic finger flexors leads to immediate spasticity reduction, increased active range of motion, and decreased frequency of motor unit spontaneous firing spikes. The results suggest that latent trigger points possibly exist in spastic muscles and they contribute partly to spastic hypertonia of finger flexors in chronic stroke.

Hip abductor function following lateral Hardinge approach

Background Although the direct lateral approach to the hip gives excellent exposure of the hip joint and a clear operating field, this approach creates a potential functional risk for the abductor musculature by damaging the superior gluteal nerve or inadequate reinsertion of the musculotendinous cuff into the greater trochanter. The present study investigates the incidence of clinical and electrophysiological evidence of damage to the superior gluteal nerve after this approach. Objective The aim of this study was to evaluate the role of needle EMG in the assessment of hip abductors function following lateral approach of the hip. Patients and Methods Sixty cases were subjected to Hardinge lateral approach in the department of orthopedic surgery and traumatology, Menoufia University Hospital from March 2014 to March 2016. Hemiarthroplasty, after a fracture of the neck of the femur, was performed in 30 patients and total hip replacement for advanced osteoarthritis of the hip joint in 30 patients. After operation all patients were assessed clinically and electrophysiologically. Results In base line EMG performed three weeks postoperatively to all patients, 18 patients (30%) showed EMG evidence of acute denervation of hip abductors while the remaining 42 patients (70%) showed normal EMG studies. Conclusion EMG detection of superior gluteal nerve injury was frequent in lateral approach to the hip. The injury recovered spontaneously within 3 months post-operatively. Good surgical technique and awareness of the anatomy of the nerve supply are the key factors in preserving good abductor strength.

Ultrasound guidance increases diagnostic yield of needle EMG in plegic muscle

ObjectivesTo increase the specificity of motor unit potential (MUPs) detection by using ultrasound guided electromyography (USG-EMG) in patients with muscle plegia due to traumatic nerve lesions. MethodsForty-six patients with recent nerve trauma underwent baseline standard EMG (ST-EMG) evaluation with evidence of absent MUPs. In 41 of them, ST-EMG was repeated after 2–3 months (T1) and the patients were accordingly divided in two groups: ST-EMG+ (if MUPs were detected) or ST-EMG- (MUPs not detected). Then, ST-EMG- patients underwent muscle ultrasound evaluation (M-US) and, if isles of muscular contractility were found, they also had USG-EMG. The same protocol was repeated 4–6 months after baseline (T2). ResultsAt T1, 22/41 patients were ST-EMG+. While 19/41 were ST-EMG-; 9 of these patients had M-US consistent with residual muscular activity, for that reasons underwent USG-EMG with 7 of 9 demonstrating MUPs (at T2 all of these 7 patients resulted ST-EMG). In the other 2 patients, we found no MUPs at T1 but they became ST-EMG+ or USG-EMG positive at T2. The remaining 10 ST-EMG- patients had no EMG or US evidence of muscle contraction at T1, but at T2 2 of 10 became ST-EMG+ and 2 had USG-EMG showing MUPs. In the remaining 6 patients still M-US negative at T2, complete denervation was diagnosed. Concerning the 22 patients who were ST-EMG+ at T1, all but one showed increase of MUPs at T2. ConclusionsIn this study, we demonstrated the utility of US guidance when performing EMG evaluation in locating isles of muscular contractility in patients who have no detectable MUPs on EMG after nerve trauma. SignificanceUSG-EMG significantly increases the specificity of needle EMG allowing earlier detection of MUPs.

The needle EMG findings in myotonia congenita

IntroductionMyotonia congenita (MC) is caused by pathogenic variants in the CLCN1 gene coding the chloride channel protein. MethodsTo test the hypothesis that needle EMG could be helpful in distinguishing between the recessive and dominant MC, we performed EMG examination in 36 patients (23 men) aged 4–61 years with genetically proven MC: in 30 patients with autosomal recessive MC (Becker MC) and in 6 with autosomal dominant MC (Thomsen MC). ResultsMyotonic discharges were recorded in 95.8% of examined muscles. For the whole MC group we observed a significant positive correlation between parameters of motor unit activity potentials (MUAPs) in vastus lateralis and tibialis anterior muscles and the duration of the disease. Similar correlation for biceps brachii also was found in Becker MC subgroup only. DiscussionEMG could still be helpful in diagnosis of MC and together with provocative tests might be useful in differentiation between recessive and autosomal MC.

Verification of intramuscular electromyography electrode placement for neuromuscular partitions of infraspinatus

The infraspinatus muscle is composed of three neuromuscular partitions: superior, middle and inferior. Although methods for fine-wire EMG electrode insertion into these partitions have been developed and used, it has yet to be verified. The purpose of this cadaveric EMG needle placement study was to assess the accuracy and reproducibility of a protocol used to target the three partitions of infraspinatus. On seven shoulder specimens, two investigators inserted needles into each superior, middle and inferior partition according to a previously developed protocol. Each was blinded to the other’s insertion sites. The specimens were dissected and the location of each needle was digitized and modeled in 3D. Of the 42 needles that were inserted, 32 were placed in the targeted partition. The highest accuracy rate occurred for the middle partition (100%), followed by the inferior (71.4%) and then the superior (57.1%). When the needles were not placed in the targeted partition, they were located in the neighboring partition within infraspinatus or the teres minor muscle. The current study showed the middle partition could be targeted accurately, whereas the superior and inferior partitions were more challenging. Ultrasound guidance may be necessary to ensure accurate placement into all parts of infraspinatus.

P47-T Could needle EMG still be helpful in diagnosis of myotonia congenita?

Background Myotonia congenita (MC) is the most common nondystrophic myotonia caused by loss of function mutations in the CLCN-1 chloride channel. Aims: The purpose of this study was to describe detailed EMG characteristics of patients with MC as well as to test the hypothesis that needle EMG could help to distinguish between the recessive and dominant form of MC. Material and methods We evaluated 36 patients (23 men) aged 4–61 years with genetically proven MC. In 30 patients (19 men) autosomal recessive form of MC (BMC) and in 6 – autosomal dominant MC (TMC) was recognized. We analyzed EMG results for motor unit action potential (MUAP) morphology as well as the occurrence and distribution of myotonic discharges (MD). Results were recorded in 95.8% of examined muscles, in almost 100% muscles of patients with BMC and in about 80% muscles in TMC subgroup. The were described as common (in BMC) or widespread in TMC especially in distal limb muscles (first interosseous dorsalis and tibialis anterior, TA) where differences between groups reached statistical significance. For the whole MC group we observed a statistically significant positive correlation between MUAPs parameters in vastus lateralis and TA muscles and the duration of the disease. Similar correlation for biceps brachii muscle, was found in BMC. Conclusions This study supported the hypothesis that needle EMG could still be helpful in diagnosis of MC and together with short exercise and short exercise with cooling tests might be useful in differentiation between BMC and TMC.

P32-S Application of decomposition based quantitative EMG (DQEMG) to focal neuropathies

Background EMG signals can be decomposed into their constituent motor unit potential trains and further analyzed using specific signal processing algorithms which provide novel and useful information regarding the temporal and electrophysiological behaviour and morphological attributes of motor units. In low to moderate stages of focal neuropathies (when only focal demyelination or low axonal sensory affection is registered) traditional needle EMG evaluation is usually normal. However, DQEMG provides evidence of motor unit instability in a significant portion of otherwise normal muscles. Material and methods 20 case and 9 control subjects were studied with median and ulnar ENG, quantitative EMG and DQEMG (abductor pollicis brevis, first dorsal interosseus or abductor digiti minimi). Patients with symptoms suggesting focal median or ulnar neuropathies were selected as cases, except for those showing low-median compound muscle action potential amplitudes or needle EMG abnormalities. Control subjects were included when no ENG nor needle EMG abnormalities findings were encountered. Results 75% of cases with any focal demyelinating finding showed instability features in DQEMG, which were also found in 43% of the normal ENG and control groups. Applying more restrictive DQEMG criteria, instability was found in 63% of cases with focal ENG alterations and 43% with normal ENG, while the control group showed no abnormalities. Conclusions Decomposition-based quantitative EMG is a novel and more powerful tool for detecting abnormalities in motor unit potentials, compared with the classical quantitative or semi-quantitative needle EMG analysis.

P87-F Severe congenital myopathy related to a novel mutation in the titin gene. A case report

Mutations in the titin gene (TTN) are related to a wide spectrum of disease. In recent years, congenital titinopathy has emerged as a cause of severe early onset myopathy. A case of two female sisters born at 32 weeks of gestation by cesarean section, from a non-consanguineous, healthy couple. They had normal prenatal ultrasounds except from equinovarus foot in one twin. Apgar score was low at birth (6–10 at 1 and 5 min in both). Both girls needed ventilator support because of respiratory insufficiency, severe axial hypotonia, multiple joint contractures distal and proximal and multiple long bone fractures. Chromosomopathy and osteogenesis imperfect were ruled out in the Genetic unit of our institution. Cardiological studies were normal. The neurographic study performed at two months of life showed extremely low amplitudes of the CMAPs with normal conduction velocities and relative preservation of the SNAPs, without clear myopathic features or spontaneous activity in the needle EMG. The whole exome sequencing (GenExComplete) revealed two extremely rare mutations in the titin gene, only expressed in the fetal skeletal transcript of TTN. One of the twins died at 8 months of age from pneumonia and the other baby needs mechanical ventilation for life support to date. In a case of severe congenital myopathy without cardiac involvement, it is essential to consider the global clinical context. Although very rare, mutations in the fetal skeletal transcript of TTN should be excluded.

P88-F Electromyographic findings in our cohort of patients with congenital muscular dystrophies and congenital myopathies

Introduction Congenital myopathies (CM) followed by Congenital muscular dystrophies (CMDs) are the most common muscular cause of floppy infant syndrome. It is well known that EMG pattern in both groups is similar, but it is recently described a characteristic association between peripheral neuropathy and some congenital muscular dystrophies. The objective of this presentation is to describe the EMG findings in our cohort. Material and methods We reviewed retrospectively charts and EMG studies of patients with genetically confirmed Cand CM followed in our Hospital in order to evaluate the pattern of EMG involvement. Results All patients showed proximal myopathic changes at EMG. Only one patient with DMC had spontaneous activity at rest (LAMA2). Three patients shared a mixed pattern: First patient with col VI myopathy showed a distal motor axonal neuropathy (similar to distal motoneuron disease), the second one with col VI myopathy displayed minor motor conduction abnormalities but with loss of motor unit at distal muscles and a third patient with LAMA2 Cexhibited isolated sensory motor desmyelinating findings. Conclusions In our cohort only 37% of Cpatients show association of neuropathy and myopathy at EMG. In patients with floppy infant syndrome we suggest to perform nerve conduction studies and needle EMG at proximal and distal muscles to evaluate the association between myopathy and motor neuropathy to achieve a correct electrodiagnosis. It will be interesting to perform longitudinal studies to know if neuropathy is a finding that develops during the follow up and if it depends on the type of genetic abnormality.

O-30 Micro-EMG: Imaging human motor units using a novel intramuscular electrode array

Background State of the art clinical EMG provides only indirect or inferred measurements of muscle structure. Structural information for motor units has only previously been described using laborious glycogen depletion experiments. Micro-EMG is a novel multi-electrode system that samples EMG signal from 64 electrodes along the surface of the needle in order to localise the muscle fibres of multiple human motor units along the length of a clinical EMG needle. This enables mapping of human motor units from just 5 min recordings. Methods We recorded multi-electrode EMG activity at varying force levels (10–40% of maximum voluntary contraction) in the biceps and tibialis anterior muscle of 6 healthy volunteers. Each EMG channel was decomposed into motor unit action potentials, and fibre action potentials spatially localised using a signal deconvolution method. Features normally only accessible via histology including fibre nearest neighbour distance and all-pairs distance were calculated. Several simulations of muscle electrical activity were created in order to test the accuracy of localisation. Results For the first time, we were able to produce an electrical localisation map of the human motor unit in vivo. A total of 340 fibres in 31 motor units were isolated and localised. Median nearest neighbour distance varied from 0.44 to 1.02 mm. Simulation findings indicated strong accuracy in fibre number estimation and localisation. Conclusions Micro-EMG provides unprecedented insights into motor unit structure and function. We anticipate that this method will provide useful biomarkers for disease states such as motor neurone disease.

SPiQE: An automated analytical tool for detecting and characterising fasciculations in amyotrophic lateral sclerosis

ObjectivesFasciculations are a clinical hallmark of amyotrophic lateral sclerosis (ALS). Compared to concentric needle EMG, high-density surface EMG (HDSEMG) is non-invasive and records fasciculation potentials (FPs) from greater muscle volumes over longer durations. To detect and characterise FPs from vast data sets generated by serial HDSEMG, we developed an automated analytical tool. MethodsSix ALS patients and two control patients (one with benign fasciculation syndrome and one with multifocal motor neuropathy) underwent 30-minute HDSEMG from biceps and gastrocnemius monthly. In MATLAB we developed a novel, innovative method to identify FPs amidst fluctuating noise levels. One hundred repeats of 5-fold cross validation estimated the model’s predictive ability. ResultsBy applying this method, we identified 5,318 FPs from 80 minutes of recordings with a sensitivity of 83.6% (+/− 0.2 SEM), specificity of 91.6% (+/− 0.1 SEM) and classification accuracy of 87.9% (+/− 0.1 SEM). An amplitude exclusion threshold (100 μV) removed excessively noisy data without compromising sensitivity. The resulting automated FP counts were not significantly different to the manual counts (p = 0.394). ConclusionWe have devised and internally validated an automated method to accurately identify FPs from HDSEMG, a technique we have named Surface Potential Quantification Engine (SPiQE). SignificanceLongitudinal quantification of fasciculations in ALS could provide unique insight into motor neuron health.

Evaluating neurological injury in Hirayama disease using threshold tracking technology

Objective To investigate the efficacy of neurological injury in patients with Hirayama disease using threshold tracking technique. Methods This study included 17 patients with Hirayama disease who visited the Department of Orthopaedics of Huashan Hospital from June 2017 to October 2017 (patient group, 16 males and 1 female, the average age was 18.06±0.50 years, ranging from 16 to 22 years, the average course of disease was 27.2±18.81 months, ranging from 1 to 60 months. Meanwhile, a total of 20 healthy volunteers (control group, 19 males and 1 female, the average age is 20.05±1.30 years, ranging from 17 to 23 years) were also enrolled in this study. In patient group, the median motor nerve conduction examination, needle EMG examination, and threshold tracking examination were performed on the severe side; while in control group, the median motor nerve conduction examination and threshold tracking examination were performed on either side. We evaluate the changes in peripheral motor nerve conduction of Hirayama disease by comparing CMAP (compound muscle action potential) and median motor nerve conduction velocity evaluate the changes in motor nerve excitability by comparing the rheobase, SDTC (Strength-duration time constant), threshold electrotonus, current-threshold I/V slope, superexcitability, and subexcitability. The upper limb function was assessed by disabilities of arm, shoulder and hand (DASH) score. The differences in threshold tracking parameters between groups were compared by independent t test, and the correlation between SDTC and DASH score was tested by Pearson correlation analysis. Results In the peripheral motor nerve conduction examination, the median nerve CMAP in patients with Hirayama disease was 4.12±1.43 mV in average, which is lower than healthy controls 8.23±1.61 mV (t=-3.8, P<0.01). There was no significant difference in the peripheral motor nerve conduction velocity (t=-0.86, P=0.39). In the threshold tracking examination, SDTC in patients with Hirayama disease was 0.48±0.09 ms, which was prolonged than healthy controls 0.39±0.06 ms (t=3.75, P<0.01). The absolute values of TEh (10-20) and TEh (20-40) decreased significantly (P<0.01), hence, the hyperpolarized part of the threshold-electrotonus curve showed fanning-in pattern. The slope of the current-threshold (I/V) curve had a decreasing trend. The hyperpolarized I/V slope in patients with Hirayama disease was 0.27±0.09 in average, which was lower than the healthy controls which was 0.34±0.07 (t=-2.73, P=0.01). The DASH score of patients ranged from 0.86 to 19.44, with an average of 6.99±5.79. There was a correlation between SDTC and DASH score, R2=0.36, which met the F test (P=0.01). Conclusion Threshold tracking technique can be adapted in evaluating nerve injury in Hirayama disease to determine the degree of injury and potential pathogenesis. Key words: Cervical vertebrae; Spinal cord compression; Upper extremity; Muscular atrophy; Spinal fusion; Electromyography

Bilateral thigh compartment syndromes from extended sitting with forward bending

Alcohol consumption and subsequent sleeping in unusual positions often causes compression neuropathies. In this case, we experienced a unique case of bilateral leg palsy after sleeping in a forward bending position that was photographed by his colleague. We expected that prolonged blockage of the circulation of the femoral arteries resulted in bilateral thigh compartment syndromes (TCSs), leading to sciatic nerve damage. The muscle MRI and needle EMG support this hypothesis. A couple of similar cases have been reported, but the causes of TCS was undetermined due to lack of medical history. This case illustrates that atraumatic compartment syndrome with sciatic nerve palsy can be occurred by prolonged unusual positions.

Motor Unit Number Index (MUNIX) as a biomarker of motor unit loss in post-polio syndrome versus needle EMG

MUNIX method (Motor Unit Number Index) had been not used to assess number of motor neurons in post-polio syndrome in contrary to needle electromyography. ObjectivesTo confirm if MUNIX reflects motor unit loss and clinical stage and to assess difference in MUNIX and EMG results between muscles in different stage. Methods132 Muscles (MUNIX) and 96 (EMG) in 12 patients were studied and divided into groups: with normal strength(N), stable weakness and atrophy(S), new weakness and atrophy(W). ResultsIn PPS group MUNIX global was 561.36 ± 282.6 (right 6 muscles) and 561.27 ± 281.1 (left) significantly lower than in control group (six muscles 1139.6 ± 164.5) (p < 0.05). MUNIX global correlated with MRC global. MUNIX was greater in muscles with normal strength (95–100% of normal values) than in those with stable weakness (48%-0% of normal values) and new weakness (65%-0% of normal values). Respectively to clinical stage of muscle MUP (motor unit potential) amplitude increased to 350% of normal value, from 250% to 110%, and from 300% to 700%. No correlation was found between MUP parameters and MRC values. ConclusionsMUNIX reflects motor dysfunction and could be a good biomarker for loss of motor neurons in PPS.

Ultrasonography-guided electromagnetic needle tracking in laryngeal electromyography

The clinical evaluation of vocal fold movement disorders should contain the electromyography of the laryngeal muscles (LEMG). The most challenging point in LEMG is the right positioning of the EMG needle in the small target muscles. As the results of the EMG have great influence in the decision of treatment it is important to confirm the results of this examination. Anatomical structures of the larynx should be identified with laryngeal ultrasonography and the ultrasonography (US)-guided electromagnetic needle tracking should guide the LEMG needle to the target muscle. The thyroarytenoid (TA) and cricothyroid (CT) muscles had been evaluated in 19 patients (20 examinations). The US-guided transcutaneous LEMG using electromagnetic needle tracking was performed by one ENT doctor and all examinations had been video monitored. The videos were analyzed for the accuracy rate and the visibility of the important laryngeal structures. The laryngeal structures were identified in all the cases using laryngeal ultrasonography. The examination times of the US-guided LEMG were acceptable (8min, 32s). The US-guided LEMG was feasible in 56 (36 TA, 20 CT) examinations. The TA and CT could be visualized successfully but in 17 examinations (30%) the signal was not stable. We could still reach the target muscles in more than 50% of these cases. US-guided electromagnetic needle tracking in LEMG helps to determine the exact position of the laryngeal structures. With further technical improvement of the stability of the electromagnetic needle tracking signal the US-guided electromagnetic needle tracking of the target muscles in the larynx could help to improve the accuracy of the transcutaneous LEMG.

Neuromuscular Anatomy Update: A Useful Tool for Differential Diagnosis between Cervical Spondylosis and Related Disorders

Neuromuscular anatomy is the indispensable background for the diagnosis and differential diagnosis of cervical spondylosis (CS), i.e. cervical spondylotic radiculopathy (CSR), cervical spondylotic myelopathy (CSM) and cervical spondylotic amyotrophy (CSA). The spinal cord level is 1.5 segments below the level of the adjacent vertebral body. For instance, lesion at the C5/6 intervertebral foramen causes C6 radiculopathy, whereas the cord compression at the C5/6 level presents segmental signs at C7 level. The dorsal rami of spinal nerve run down several segments from the original intervertebral foramen, which is thought to be the reason why back, especially interscapular pain is often experienced in CS. Multifidus is innervated by the single adjacent root and should be chosen for the needle EMG examination of the paraspinal muscles to document the cervical lesion. Spinal accessory nerve innervating the Trapezius runs upward within the spinal canal and is relatively spared in CS. Dermatome and myotome are the most important knowledge to be mastered. I created an original myotomal chart based on my experiences, some of which have been published. If we evaluate neurological signs with the basis of correct neuroanatomy, we can make 80% correct diagnoses. This is complemented by neuromuscular electrodiagnosis, also based on neuroanatomy.

Development of radiofrequency ablation devices with neuromonitoring system to detect recurrent laryngeal nerve in thyroid nodule

Background Radiofrequency ablation (RFA) is an emerging minimally invasive treatment modality of benign thyroid nodule and limited small papillary thyroid cancer. Among the RFA related complications, the recurrent laryngeal nerve (RLN) damage is one of the most concerned complications. To reduce the RLN injury during RFA, we developed a RFA device with intraoperative neuromonitoring system (IONM) to detect recurrent laryngeal nerve. Furthermore, to avoid a use of EMG tube requiring general anesthesia, we developed an accelerometer sensor that can be attached on the anterior neck skin. In this study, we examined the feasibility of neuromonitoring system to detect RLN during RFA in thyroid gland. Methods Three beagles (six thyroid glands) underwent the RFA under general anesthesia. Tip of the RF electrode acted as a neurostimulator probe and its location was ultrasonographically monitored. Stimulation current was set based on NIM-Response 3.0 system. During the procedure, nervemonitoring was performed simultaneously using NIM® standard EMG reinforced tube, needle electrode and accelerometer. Results When the tip of the RF electrode was placed near the tracheoesophageal groove, RLN was successfully identified with EMG tube, needle electrode and accelerometer sensor. After RFA near the tracheoesophageal groove, nerve injury was detected in EMG tube, needle electrode and accelerometer sensor. Conclusion Neuromonitoring system to detect RLN using RF electrode was feasible in the animal study. Like both EMG tube and needle electrode, the accelerometer sensor can detect laryngeal muscle twitching during RLN stimulation. Accelerometer sensor for detecting RLN is expected to make the RFA procedure safer without any invasive monitoring system.

Chapter 12 - Upper extremity neuropathies

This chapter covers the electrodiagnostic (EDX) evaluation of upper extremity nerves and the brachial plexus. Carpal tunnel syndrome is the most common peripheral nerve disorder of the upper extremity. A number of techniques are used but there is no gold standard approach for its diagnosis. Needle EMG aids in the differentiation of proximal and distal median neuropathies. Ulnar neuropathy at the elbow and ulnar neuropathy at or distal to the wrist can be distinguished by EDX techniques. Radial neuropathy at the spiral groove has a specific EDX pattern. EDX assessment of proximal upper extremity nerve lesions such as brachial plexopathy is a valuable tool for exploring the diagnosis and differential diagnosis of this complex disorder.

Chapter 18 - Normal and abnormal voluntary activity

An important component of needle EMG entails recording and interpreting the electrical signals generated from motor units during voluntary contraction. The recorded motor unit potentials (MUPs) reflect the number of motor units within a muscle and the distribution and density of muscle fibers within a motor unit within a portion of a muscle. Various MUP parameters are assessed to determine the integrity of the motor units, including recruitment, stability, phases and turns, duration, and amplitude. Each of these parameters is altered in a different way in various neuromuscular diseases. In neurogenic disorders, the earliest changes occur in the recruitment pattern of motor units followed by MUP morphologic changes (increased MUP phases and duration) as reinnervation occurs. MUP instability, indicating impaired neuromuscular transmission, also occurs in reinnervating neurogenic disorders as well as in neuromuscular junction disorders. In myopathies, a reduction in the size of the motor unit is manifested by MUPs of low amplitude and short duration. Interpreting the voluntary MUP changes along with spontaneous activity helps to determine the type, severity, and temporal course of neuromuscular diseases.