Needle Electromyographic Examination Research Articles

Concentric needle jitter analysis of the genioglossus muscle in patients with motor neuron disease

ABSTRACT Objectives Difficulty relaxing the genioglossus muscle makes the evaluation of spontaneous activity problematic in patients with motor neuron disease (MND). We performed jitter analysis using conventional disposable concentric needle electrodes (CNEs) of the voluntarily activated genioglossus muscle in patients with and without MND to detect the denervation-reinnervation process. Methods CNE jitter analysis was performed at the genioglossus muscle in 21 MND(+) patients and 22 MND(–) subjects. The jitter analysis was considered abnormal if the jitter values exceeded these limits for the mean consecutive difference (MCD) or the individual MCD in more than 10% of readings. Results Seventeen MND(+) patients (81%) had at least three abnormal individual jitter values whereas denervation findings were obtained in eleven of them during the needle electromyographic examination at genioglossus muscle. None of the MND(–) subjects showed CNE jitter abnormality. Conclusion CNE jitter analysis of genioglossus muscle may provide an useful information that may be suggestive of a diagnosis of MND/ALS.

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.

Comparison of the effects of dry needling technique and combination of different manual therapy techniques on electrophysiological and psychological status in patients with myofascial pain syndrome - randomized, controlled, single blind, a pilot study

Aims: Our aim was to compare the electrophysiological and psychometric properties of the effects of the dry needling technique, graston technique, and muscle energy technique in treating myofascial pain syndrome. Methods: The study included 21 patients diagnosed with myofascial pain syndrome (MPS) and an active trigger point in the upper trapezius muscle. The patients were randomly divided into three groups of 7 each. The first group received only exercise and dry needling technique (DNT), the second group received graston technique (GT), muscle energy technique (MET) and exercise, and the third group received only exercise. Evaluations were conducted before and after treatment. The trigger point detected with an algometer in the upper trapezius muscle was evaluated with needle electromyography (EMG). The study used the Beck Depression Inventory (BDI) to determine its effects on psychological state. Results: The change in EMG variable over time was significant in each treatment group (p<0.05). The improvement in EMG change was more pronounced in the DNT group compared to the other groups. There was also a significant decrease in BDI scores before and after treatment (p<0.05). Pairwise comparison analysis revealed an improvement in the BDI scores of all groups, except the control (exercise) group, after treatment, when compared to pre-treatment. Conclusion: During the trigger point needle EMG examination of all subjects in the study, we detected spontaneous muscle activity (SMA) in addition to entry activity. After treatment, we observed improvement in SMA. These results suggest that the applied techniques are effective in treating trigger points.The effectiveness of the applied techniques can be evaluated in terms of creating alternatives.

Optimal timing of needle electromyography to diagnose lesion severity in traumatic radial nerve injury.

In patients with traumatic radial nerve injury (RNI), the chance of spontaneous recovery must be balanced against the benefits of early surgical reconstruction. We aimed to explore the time-specific value of needle electromyography (NEMG) to diagnose nerve lesion severity. In this retrospective diagnostic accuracy study at Leiden Nerve Center, patients at least 12 years of age with RNI caused by fractures or fracture treatment were included. The sensitivity and specificity of the patients' first NEMG examination were assessed, stratified by the timing after the nerve injury. The absence of motor unit potentials (MUPs) in muscles distal to the nerve lesion was considered a positive test result. Lesion severity was dichotomized to moderate injury (spontaneous Medical Research Council grade ≥3 recovery) or severe injury (poor spontaneous recovery or surgical confirmation of a mainly neurotmetic lesion). Ninety-five patients were included in our study. The sensitivity of NEMG to detect severe RNI was 75.0% (3 of 4) in the fourth, 66.7% (2 of 3) in the fifth, and 66.7% (2 of 3) in the sixth month after the nerve injury. The specificity in the first to the sixth month was 0.0% (0 of 1), 50.0% (2 of 4), 77.3% (17 of 22), 95.5% (21 of 22), 95.8% (23 of 24), and 100.0% (12 of 12), respectively. The specificity of NEMG is higher than 95% and therefore clinically relevant from the fourth month after the nerve injury onward. Absence of MUPs at this time can be considered an indication to plan nerve exploration. Moreover, the presence of MUPs on NEMG does not completely exclude the necessity for surgical reconstruction.

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

This study aimed to investigate a safe and accurate electromyographic needle insertion site of the rhomboid major (RM) muscle using cadaver dissection. Dissection of the trapezius and rhomboid major muscles around the scapula was performed in 18 scapulae from nine fresh cadavers. The point (point A) at which the lateral margin of the lower trapezius muscle crossed the medial border of the scapula and the distal insertion point (point DI) of the rhomboid major muscle to the medial scapula were determined. The midpoint (point M) between points A and DI was also determined. The distance from the inferior angle of the scapula to each point was measured. The length of the medial scapula was 12.9 ± 1.2 cm from the root of the scapular spine to the inferior angle of the scapula. Points A, DI, and M were located at a mean distance of 8.4 ± 0.7, 1.8 ± 0.4, and 5.1 ± 0.5 cm proximal to the inferior angle of the scapula, respectively. Needle electromyographic examination of the rhomboid major muscle can be performed safely and accurately using the lower part of the rhomboid major muscle, as investigated in this anatomical study.

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 > 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 < 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.

Risk factors and diagnostic methods of intensive care unit-acquired weakness

To explore the risk factors of intensive care unit-acquired weakness (ICU-AW) and the characteristics of Medical Research Council (MRC) score and electromyogram. A case control study was conducted. Patients with mechanical ventilation ≥ 7 days and MRC score admitted to department of respiratory and critical care medicine of China-Japan Friendship Hospital from September 2018 to January 2020 were enrolled, and they were divided into ICU-AW group (MRC score < 48) and non-ICU-AW group (MRC score ≥ 48) according to MRC score. The general situation, past medical history, related risk factors, MRC score, respiratory support mode, laboratory examination results, electromyogram examination results, ICU-AW related treatment, outcome and length of ICU stay were collected, and the differences between the two groups were compared. The risk factors of ICU-AW were analyzed by binary multivariate Logistic regression, and the characteristics of MRC score and electromyogram were analyzed. A total of 60 patients were enrolled in the analysis, including 17 patients in ICU-AW group and 43 patients in non-ICU-AW group. Univariate analysis showed that there were significant differences in acute physiology and chronic health evaluation II (APACHE II) score, sequential organ failure assessment (SOFA) score, brain natriuretic peptide (BNP), blood urea nitrogen (BUN) on the first day of ICU admission and the ratio of invasive mechanical ventilation between ICU-AW group and non-ICU-AW group [APACHE II score: 21 (18, 25) vs. 18 (15, 22), SOFA score: 7 (5, 12) vs. 5 (3, 8), BNP (ng/L): 364.3 (210.1, 551.2) vs. 160.1 (66.8, 357.8), BUN (mmol/L): 9.9 (6.2, 17.0) vs. 6.0 (4.8, 9.8), invasive mechanical ventilation ratio: 88.2% vs. 46.5%, all P < 0.05]. Binary multivariate Logistic regression analysis showed no independent risk factor for ICU-AW. The average MRC score of 17 ICU-AW patients was 33±11. The limb weakness was symmetrical, and the proximal limb weakness was the main manifestation. Electromyography examination showed that the results of nerve conduction examination in ICU-AW patients mainly revealed that the amplitude of compound muscle action potential (CMAP) and sensory nerve action potentials (SNAP) were decreased, and the conduction velocity was slowed down; needle electromyography showed increased area of motor unit potential (MUP), prolonged time limit and a large number of spontaneous potentials. Prognosis evaluation showed that compared with non-ICU-AW group, patients in ICU-AW group underwent more tracheotomy (70.6% vs. 11.6%), longer length of ICU stay (days: 57±52 vs. 16±8), and more rehabilitation treatment (58.8% vs. 14.0%), and the differences were statistically significant (all P < 0.01). The occurrence of ICU-AW may be related to high APACHE II score and SOFA score, high levels of BNP and BUN on the first day of ICU admission and the proportion of invasive mechanical ventilation, but the above factors are not independent risk factors for ICU-AW. The MRC score of ICU-AW patients was characterized by symmetrical limb weakness, mainly proximal limb weakness; in electromyography examination, the nerve conduction examination results mainly showed that CMAP and SNAP amplitude were decreased, and conduction velocity was slowed down; needle electromyography examination showed increased MUP area, prolonged duration and a large number of spontaneous potentials.

Which Approach Is Most Optimal for Needle Electromyographic Examination of the Biceps Femoris Short Head: Medial or Lateral?

ObjectiveTo investigate the anatomical characteristics of the biceps femoris short head (BS) and determine the optimal needle placement for BS examination.MethodsTwenty-one lower limbs were dissected. The distances from the medial and lateral margins of the biceps femoris long head (BL) tendon to the common fibular nerve (CFN) (M_CFN_VD and L_CFN_VD, respectively) and the distance from the lateral margin of the BL tendon to the lateral margin of the BS (L_BS_HD) were measured 5 cm proximal to the tip of the fibular head (P1), four fingerbreadths proximal to the tip of the fibular head (P2), and at the upper apex of the popliteal fossa (P3).ResultsThe BS was located lateral to the BL tendon. The CFN was located along the medial margin of the BL tendon. The median values were 2.0 (P1), 3.0 (P2), and 0 mm (P3) for M_CFN_VD; and 17.4 (P1), 20.2 (P2), and 21.8 mm (P3) for L_CFN_VD; and 8.1 (P1), 8.8 (P2), and 13.0 mm (P3) for L_BS_VD.ConclusionThe lateral approach to the BL tendon was safer than the medial approach for examining the BS. Amore proximal insertion site around the upper apex of the popliteal fossa was more accurate than the distal insertion site. In this study, we propose a safer and more accurate approach for electromyography of the BS.

Needle Electromyography, F-Wave, and H-Reflex: A Critical Reappraisal of Their Utility in the Diagnosis of Various Sensory Symptoms in the Extremities and Spine in the Setting of Normal Neurological Examination

Objective: Health care providers refer their patients to electromyography (EMG) laboratories for the evaluation of various sensory symptoms in the extremities and spine. The procedure is usually performed in conjunction with transcutaneous electrical stimulation of peripheral nerves and elicitation of the F-wave and H-reflex. The present study aimed to determine the real value of these procedures in the diagnosis of sensory symptoms in the setting of a normal neurologic examination. Method: The EMG reports and clinical histories of 100 patients, including 10 patients evaluated by other electromyographers, were reviewed. The study was focused on those with normal neurological examinations and those without histories of ongoing medical disorders and major surgeries to the extremities and spine. Results: All EMGs, F-wave, and H-reflex reports reviewed were normal, including those obtained from the second procedure performed in some patients and of those who subsequently underwent spinal surgery. Neurologic examination in all patients was normal. Conclusion: Needle EMG, F-wave and H-Reflex examinations are predictably normal in patients with non-dermatomal, non-neuropathic sensory symptoms with normal neurologic examination and without history of preexisting medical and surgical disorders. A good neurologic examination should determine the need to perform these procedures. Our findings have important diagnostic, therapeutic, prognostic, economic and legal implications.

Sonographic Evaluation of the Optimal Needle Insertion Site in the Biceps Femoris Short Head.

The aim of the study was to identify the optimal needle placement for electromyographic examination of the biceps femoris short head muscle in relation to the biceps femoris long head tendon through sonographic evaluation. This cross-sectional observational study involved 36 lower limbs of 18 healthy volunteers. The distances and angles indicating the relationships between the common fibular nerve and the medial or lateral border of the biceps femoris long head tendon were measured at 5 and 7 cm proximal to the tip of the fibular head (P1 and P2, respectively) using ultrasonography. The median values of the distance between the biceps femoris long head tendon and the common fibular nerve were significantly longer in the lateral approach than in the medial approach at the P1 and P2 levels. The median values of the angles between the vertical line to the biceps femoris long head tendon and the common fibular nerve were significantly larger in the lateral approach than in the medial approach at both levels. The common fibular nerve is located just below the medial border of the biceps femoris long head tendon at a near-vertical degree from the skin. It is strongly recommended that the needle should be inserted on the lateral side of the biceps femoris long head tendon during needle electromyographic examination of the biceps femoris short head muscle.

Iatrogenic injury and regeneration of the facial nerve after parotid gland tumour surgery: a pilot study with clinical and neurophysiological assessment

Introduction. Benign tumour surgery of the parotid gland may cause iatrogenic injury of the facial nerve, with results of postoperative treatment depending on the type of injury. The study aimed to clarify the mechanism of facial nerve injury after benign tumour surgery of parotid gland. Materials and Methods. The effectiveness was verified preoperatively and 1, 3, 6 and 17 months postoperatively. House-Brackmann scales, electroneurography, blink reflex study and needle electromyography were performed. Pharmacological treatment (Galantamine, Cocarboxylase, Dexamethasone, Triamcinolone) and supervised physiotherapeutic procedures (Facial-Oral-Tract-Therapy, Proprioceptive neuromuscular facilitation) were applied for six months. Results. Tumour removal led to the total paralysis of the left facial nerve, IV, III and III House-Brackmann grades were ascertained at the subsequent 3rd–5th periods of observation. In postoperative studies, electroneurography results showed full functional recovery of the frontal branch and incomplete regeneration in the marginal mandibular branch. Blink reflex examination showed proper parameters of evoked potentials only during preoperative and the last observation period. Residual voluntary activity of the frontal muscle and weak voluntary activity of orbicularis oris muscle were recorded in the needle electromyography examination. Contracture of mimic muscles at rest and improvement of their voluntary activity on the left side was observed six months after surgery compared to the early period of observation. Conclusion. Consecutive studies showed the predominant axonal type of injury in the marginal mandibular branch and neuropraxia effect of the facial nerve, allowing the creation of a rehabilitation programme optimal for the functional recovery of the nerve.

Orthostatic Jaw Tremor, a Diagnostic Challenge for Neurologists

Jaw tremor is usually associated with tremor or other abnormal involuntary movements affecting additional body parts, but isolated jaw tremor is a rare clinical presentation. A 40-year-old man presented with history of paroxysmal jaw tremor for 3 years with no other neurological symptoms, psychiatric conditions, or a family history of neurological disorders. The tremor occurred only in the resting jaw position, with 10 episodes per day on an average, and lasted from 10 minutes to hours. It disappeared with any voluntary activation of the masseter muscle and did not change (in amplitude or frequency) with distraction maneuvers. The remainder of neurologic examination was unremarkable. The patient underwent extensive testing, including contrast-enhanced brain magnetic resonance imaging, blood tests and neuropsychiatric evaluation by two different neuropsychiatrists which failed to reveal the underlying cause. The needle electromyography examination revealed involuntary, intermittent, and synchronized muscular contractions in both masseter muscles, at a frequency of 13 to 14 Hz. No changes were discovered in the other muscles. He was treated with propranolol, primidone, valproic acid, diazepam, and amitriptyline, but the response was not significant. Injection of 25 units of botulinum toxin type A in the masseter muscle on both sides of the fac was effective five days after the injection. No adverse effects or masseter weakness were observed.

Lidocaine injections and neck corset wearing improve dropped head syndrome in Parkinson's disease and related disorders

BackgroundPatients with Parkinson's disease and related disorders (PDRD) may exhibit dropped head syndrome (DHS), which does not yet have an effective treatment. ObjectivesTo evaluate the effect of combining lidocaine injection into the bilateral scalene muscles and neck corset wearing on dropped head syndrome. MethodsWe performed needle electromyography assessments of the scalene, sternocleidomastoid (SCM), levator scapulae, splenius capitis, and trapezius muscles. Patients received 2.5–5 ml injections of 1% lidocaine into both sides of the scalene muscles for 4/5 consecutive days and were instructed to wear a neck corset. We measured the neck flexion angle, which formed between the horizontal line and the straight line passing through the ear canal and orbital fossa, before (baseline) and after (Day 8 and Day 90) the intervention. ResultsSeven males and eight females (mean age, 68.9 years; range 56 to 85 years) who had PDRD with dropped head syndrome were enrolled in this study. Needle electromyography examination revealed abnormal discharge of the scalene muscles in all patients when the neck position was corrected; however, some patients did not show abnormal discharge of the SCM muscle. At Day 8, we observed an improvement of the neck flexion angle in 13 of the 15 patients, from an average of 27.7° ± 13.9° to 11.7 ± 14.6°. At Day 90, the average neck flexion angle was 15.3° ± 17.2°. ConclusionsCombining lidocaine injection into the scalene muscles and neck corset wearing is an effective treatment regimen for DHS in patients with PDRD.

Musculocutaneous neuropathy.

Isolated musculocutaneous neuropathy is uncommon. In this study we aimed to determine its causes and clinical presentation and interpret the electrodiagnostic findings associated with this condition. Our investigation was a retrospective review of patients diagnosed with musculocutaneous neuropathy at the Mayo Clinic (Rochester, Minnesota) electromyography (EMG) laboratory between 1997 and 2015. Thirty-two patients with musculocutaneous neuropathy and 5 patients with lateral antebrachial cutaneous neuropathy were identified. The most common cause was acute trauma or surgery (65%). Fourteen percent of the cases were idiopathic and 14% were inflammatory. Pain and sensory disturbance were more common presentations than weakness. Weakness from nerve injury was not noted in 2 patients, suggesting that other muscles may provide adequate elbow flexion/supination. The bilateral absence of lateral antebrachial cutaneous nerve sensory responses suggests an inflammatory cause. Musculocutaneous neuropathy usually results from trauma or iatrogenic injury. Nerve conduction studies alone are insufficient to confirm neuropathy, and needle EMG examination should be a routine part of the diagnostic evaluation. Muscle Nerve 58: 726-729, 2018.

The focus of the cervical radiculopathy by dermatomal pain in comparison with results of electrodiagnosis and imaging

Objectives The dermatomal pain related to a cervical radiculopathy is often misunderstanded by physicians because in most cases there is a discordance between it, imaging and electromyography (EMG). The aim of this study is to compare trajectory of dermatomal pain, imaging and EMG findings. Methods It's a retrospective study over a year that regrouped patients referred to the department of functional explorations of Sfax for electrodiagnostic test. These patients had clinical signs of cervical radiculopathy and underwent a cervical imaging (MRI or CT) that confirmed it. They underwent a nerve conduction study with a needle EMG examination that examined one muscle from the affected root and others upper and lower depending on its result and clinical finding. The Fisher's exact test was used for comparison of different clinical, imaging and EMG signs. Results Sixteen patients (sex-ratio 1/3) were collected with a mean age of 54.8 ± 11.15 year. These patients had not yet motor signs. In 6 patients the pain was not dermatomal. When the pain was dermatomal, there was a concordance between clinic and respectively imaging and EMG in 3 cases and 8 cases. Dermatomal pain was not correlated with imaging (P = 0.8) nor with EMG (P = 0.9). There was a correlation between imaging and EMG (P = 0.05). Conclusion Because the radiculopathy is due to a motor ventral nerve root compression, the most important symptom is the myotomal weakness [1] , [2] . However, dermatomal pain was the most sensitive symptom but less specific in Hassan's study [2] . In fact this symptom can be due to a combination of mechanical and inflammatory mechanisms. Imaging and EMG are often in concordance with the affected nerve root but EMG gives more evidence of the functional lesions and a more specificity [3] .

INCIDENCE AND PROGNOSIS OF RADIAL NERVE LESION ASSOCIATED WITH HUMERAL SHAFT FRACTURE

Background &#x0D; Humerus is the long bone of the arm, radial nerve which is branch from the posterior cord of the brachial plexus commonly injured by fracture shaft of humerus because of close relation to the bone during it’s course in the arm, and the average incidence of radial nerve palsy with fracture of humerus in the literature is 12%.&#x0D; Objective&#x0D; To study incidence, types and nature of radial nerve injury associated with humeral shaft fracture.&#x0D; Subjects and Methods&#x0D; This is prospective study conducted at the Sulaimani Teaching Hospital and Causality Hospital during the period of June 2009 – June 2010. The study included sixty-eight patients with fracture shaft of hummers (21 females, 47 males), with an age ranging from 6 to 75 years (mean ±SE = 40± 0.67 years). Among the 68 patients 14 of them presented with neurological deficit of radial nerve dysfunction with an age ranging from 6 to 44 years (mean ±SE = 25 ± 0.67 years) (6 female and 8 male). The entire subjects met certain inclusion and exclusion criteria. Nerve Conduction Study and needle electromyography examinations were performed for those patients with radial nerve Dysfunction. The following biochemical parameter were measured complete blood count, serum calcium, serum alkaline phosphatase also X ray examination were performed in more than one view (anterior-posterior and lateral view).&#x0D; Results&#x0D; Among 68 patients with fractured humeral shaft 14 of them presented with feature of radial nerve palsy, nerve conduction study and electromyographic result showed that 10 patients (72%) have only focal demyelinating lesion (neuropraxia), (21%) 3 patients with severe radial nerve injury (neurotmesis) and 1 patient (7%) with partial radial nerve injury (axonotmesis) with the over all prevalence of about 20.6%. Among those patients with radial nerve palsy 3 of them was presented with compound fracture and associated severe radial nerve injury (neurotmesis), the remaining 11 patients presented with closed fracture..&#x0D; Conclusions&#x0D; The incidence of radial nerve palsy with fractureed shaft humerus was 20.6%, transection of radial nerve is associated with open fractures of the humerus, nerve palsies that are part of closed fracture nearly always recovered.

Safety Window for the Volar Needle Approach for Examination of the Pronator Quadratus Using Ultrasonography

ObjectivesTo investigate pronator quadratus (PQ) anatomy and determine the proper volar needle insertion point based on landmarks, the tip of the ulnar styloid (an imaginary vertical line passing the tip of the ulnar styloid process [U line]), and the ulnar margin of the palmaris longus tendon (uPL) using ultrasonography. DesignDescriptive study. SettingDepartment of physical medicine and rehabilitation. ParticipantsParticipants between 20 and 60 years without any diseases. (N=25; 13 men, 12 women; 50 forearms). InterventionsUltrasonography. Main Outcome MeasuresThe proximal and distal volar surface points of origin, the proximal and distal insertion sites, and the midpoint of the PQ (PQ_M) were determined. The distance of each of the PQ surface indices from the U line was measured, and the probe was positioned at the level of PQ_M parallel to the U line. The relative distances from the vertical surface points of the median nerve and ulnar artery to the uPL were measured. ResultsThe mean age and body mass index were 32.7±10.4 years and 21.98±2.83kg/m2. The PQ_M was located at a mean distance of 2.63±0.35cm proximal from the U line (men 2.79±0.37cm and women 2.45±0.21cm; P<.05). The mean safety window for the volar approach was 0.72±1.8cm toward the radial side and 1.51±0.30cm toward the ulnar side from the uPL. The PQ was at a mean depth of 1.30±0.19cm from the skin and had a mean thickness of 1.19±0.24cm at the level of PQ_M. The distance between the U line and the proximal edge of the PQ, as well as the PQ thickness, was greater in men than in women. ConclusionsThe volar approach for needle electromyographic examination of the PQ can be performed precisely and safely.

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.

Needle electromyography in carpal tunnel syndrome: is it valuable or predictable?

Needle electromyography (EMG) examination is not crucial in establishing the diagnosis of carpal tunnel syndrome (CTS). However, the presence of axonal loss in needle EMG helps clinicians determine a treatment strategy such as surgery. The aim of this study was to investigate whether needle EMG in CTS patients is essentially needed or could be predicted using other nerve conduction study (NCS) parameters. This study included 100 patients with clinical and NCS-proven CTS, as well as 50 age-matched and sex-matched controls. All individuals were evaluated using electrodiagnostic techniques, including median distal latency, compound muscle action potential (CMAP), forearm motor nerve conduction velocity, median peak latency, sensory nerve action potentials, and sensory nerve conduction velocity. All CTS patients underwent EMG examination of the abductor pollicis brevis muscle, and the presence or absence of spontaneous EMG activity was recorded. Comparison of the NCS parameters between CTS patients with and without spontaneous EMG activity revealed that the main determinant parameters for spontaneous activity were CMAPs, sensory nerve action potentials, and forearm motor nerve conduction velocities. However, logistic regression analysis showed that CMAP was the most powerful predictor of the presence of spontaneous activity (P = 0.000, odds ratio = 12.154). It can be concluded that median nerve CMAP amplitudes are the most powerful predictors of the occurrence of spontaneous EMG activity. However, EMG examination is still valuable in some CTS patients and NCS cannot completely replace needle EMG examination in these patients.

Estimation of a single motor unit's threshold and activation range, a study on patients with muscular disorders.

Background:In clinical neurophysiology, threshold tracking studies are used to evaluate the functionality of a muscle through studying the functionality of its motor units (MUs) that govern the muscle. The functionality of an MU can be quantified by estimation of its excitability properties via MU's stimulus-response curve. In this study, we aim to develop a model-based approach to estimate MU's threshold mean and its activation range as indications of MU's excitability. This is a different approach from routine strategies in neurophysiology, which are mostly subjective.Methods:To assess the excitability of a single MU, needle electromyography examination was used to obtain the axonal activity of that MU. To improve estimation, the examination was repeated several times on individuals. Replication of experiment introduces serial correlation between observations. We account for this correlation by using a mixed-effects model. We investigate the appropriateness of classical logistic mixed-effects model and its Bayesian formulation for estimation purpose.Results:Both classical and Bayesian models can obtain a reliable estimation of MU's threshold. However, we found Bayesian approach to provide a better estimate of MU's activation range. Moreover, if data contain outliers both classical and Bayesian methods are vulnerable to some extent.Conclusions:Compared to the classical approach, Bayesian method is more flexible in dealing with overdispersion and provides more robust estimation of MU's parameters.