Electrodiagnostic Techniques Research Articles

Ulnar nerve motor conduction velocity correlates with body mass index in Indian young healthy subjects

Background: The prevalence of obesity is on rise globally, which poses a risk of vascular inflammation and metabolic dysregulations. Nerve conduction is affected by altered lipid metabolism, inflammation, and oxidative stress. Motor nerve conduction velocity (NCV) is a routine electrodiagnostic technique for detecting changes in nerve conduction parameters. There are contrasting results in studies done to investigate the relationship between NCV and body mass index (BMI). Few studies show increased conduction velocity with an increase in BMI, while others found either decreased or no change in conduction velocity with change in BMI. Aims and Objectives: The objective of this study was to investigate the relationship between motor NCV and BMI. Materials and Methods: In this study, we selected 27 individuals with normal weight, overweight, and obese categorized based on BMI and performed ulnar and median NCV. Correlation statistics were applied to see the relationship between BMI and motor NCV. Results: We found significant positive correlation between BMI and ulnar motor NCV (P = 0.027, r = 0.43). Ulnar and median NCV was also found correlating significant (P = 0.021, r = 0.45). Conclusion: The findings of our study suggest that the NCV correlates with BMI in lower BMI groups due to the maintenance of local optimum temperature, while in people with higher BMI inflammatory changes impair nerve conduction, a comparison in larger sample size is required to substantiate this observation is required though.

Electrodiagnosis of Lesions of Median and Ulnar Nerve Hand Sensory Branches: A Case Series.

The authors have recently tested a new electrodiagnostic technique for palmar proper digital nerves sensory nerve action potentials in normal controls. Here the authors explored whether it may offer additional information in comparison to mixed nerve wrist stimulation in a series of patients. The authors recorded palmar proper digital nerves sensory nerve action potential to selective antidromic webspace stimulation in a group of 19 patients with suspected lesions of median and ulnar nerve hand sensory branches. Coexistent carpal tunnel syndrome was present in 11 patients. The webspace stimulation technique offered additional information in 89% patients when compared with mixed nerve wrist stimulation. Webspace stimulation was informative even when carpal tunnel syndrome coexisted with damage to hand sensory branches and biased the interpretation of conventional wrist nerve conduction study. Webspace PaPDN stimulation is feasible in patients with lesion of median and ulnar nerve hand sensory branches and offer additional information in comparison with wrist-mixed nerve conduction study, also in patients with coexisting carpal tunnel syndrome.

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.

Diagnostic Value of the Second Lumbrical-Interosseous Distal Motor Latency Comparison Test in Severe Carpal Tunnel Syndrome

ObjectiveTo examine the usefulness of the second lumbrical-interosseous (2L-INT) distal motor latency (DML) comparison test in localizing median neuropathy to the wrist in patients with absent median sensory and motor response in routine nerve conduction studies.MethodsElectrodiagnostic results from 1,705 hands of patients with carpal tunnel syndrome (CTS) symptoms were reviewed retrospectively. All subjects were evaluated using routine nerve conduction studies: median sensory conduction recorded from digits 1 to 4, motor conduction from the abductor pollicis brevis muscle, and the 2L-INT DML comparison test.ResultsFour hundred and one hands from a total of 1,705 were classified as having severe CTS. Among the severe CTS group, 56 hands (14.0%) showed absent median sensory and motor response in a routine nerve conduction study, and, of those hands, 42 (75.0%) showed an abnormal 2L-INT response.ConclusionThe 2L-INT DML comparison test proved to be a valuable electrodiagnostic technique in localizing median mononeuropathy at the wrist, even in the most severe CTS patients.

A Perturbation Based Decomposition of Compound-Evoked Potentials for Characterization of Nerve Fiber Size Distributions.

The characterization of peripheral nerve fiber distributions, in terms of diameter or velocity, is of clinical significance because information associated with these distributions can be utilized in the differential diagnosis of peripheral neuropathies. Electro-diagnostic techniques can be applied to the investigation of peripheral neuropathies and can yield valuable diagnostic information while being minimally invasive. Nerve conduction velocity studies are single parameter tests that yield no detailed information regarding the characteristics of the population of nerve fibers that contribute to the compound-evoked potential. Decomposition of the compound-evoked potential, such that the velocity or diameter distribution of the contributing nerve fibers may be determined, is necessary if information regarding the population of contributing nerve fibers is to be ascertained from the electro-diagnostic study. In this work, a perturbation-based decomposition of compound-evoked potentials is proposed that facilitates determination of the fiber diameter distribution associated with the compound-evoked potential. The decomposition is based on representing the single fiber-evoked potential, associated with each diameter class, as being perturbed by contributions, of varying degree, from all the other diameter class single fiber-evoked potentials. The resultant estimator of the contributing nerve fiber diameter distribution is valid for relatively large separations in diameter classes. It is also useful in situations where the separation between diameter classes is small and the concomitant single fiber-evoked potentials are not orthogonal.

An electrodiagnostic technique for assessing palmar proper digital nerves of the hand: Normative data and clinical application.

There is no standard electrodiagnostic technique for palmar proper digital nerves (PaPDNs). In this study we investigated sensory nerve action potentials (SNAPs) to PaPDN stimulation in normal subjects and patients. SNAPs of PaPDNs were recorded in response to selective antidromic stimulation at the web space and mixed nerve stimulation at the wrist in 14 controls. The selectivity of PaPDN stimulation and the effect of recording electrode position on SNAP amplitude were studied. The technique was tested in 2 patients with PaPDN lesions. The technique yielded selective PaPDN stimulation at the web space. SNAP amplitude to PaPDN stimulation was influenced by age and was larger than SNAP amplitude to wrist stimulation. The recording electrode positions influenced SNAP amplitude. In patients, we documented PaPDN lesions, which were confirmed at surgery, whereas conventional wrist mixed nerve stimulation yielded negative findings. Selective PaPDN stimulation at the web space is feasible and may be helpful for electrodiagnosis of PaPDN lesions.

Evaluation of electrodiagnostic changes in patient with multiple sclerosis

Article type Review article Although demyelination along the axons is the main manifestation of Multiple sclerosis (MS), peripheral nervous system (PNS) could be affected potentially too. In some studies PNS involvement is estimated to be more than 50 percent in MS patients. Accordingly, objective tests to confirm the severity of PNS involvement might be crucial in patients` management. Modern technological advances lead to innovation of computerized electrodiagnostic (EDX) techniques in recent years. Nerve conduction studies (NCS) provide reliable data about neuropathies. Although the frequency of PNS involvement varies in different population of MS patients, recognizing clinical and subclinical PNS impairments in MS patients is important for the treatment.

A new electrophysiological method for the diagnosis of extraforaminal stenosis at L5-s1.

Study DesignA retrospective study.PurposeTo examine the effectiveness of using an electrodiagnostic technique as a new approach in the clinical diagnosis of extraforaminal stenosis at L5-S1.Overview of LiteratureWe introduced a new effective approach to the diagnosis of extraforaminal stenosis at the lumbosacral junction using the existing electrophysiological evaluation technique.MethodsA consecutive series of 124 patients with fifth lumbar radiculopathy were enrolled, comprising a group of 74 patients with spinal canal stenosis and a second group of 50 patients with extraforaminal stenosis at L5-S1. The technique involved inserting a pair of needle electrodes into the foraminal exit zone of the fifth lumbar spinal nerves, which were used to provide electrical stimulation. The compound muscle action potentials from each of the tibialis anterior muscles were recorded.ResultsThe distal motor latency (DML) of the potentials ranged from 11.2 to 24.6 milliseconds in patients with extraforaminal stenosis. In contrast, the DML in patients with spinal canal stenosis ranged from 10.0 to 17.2 milliseconds. After comparing the DML of each of the 2 groups and at the same time comparing the differences in DML between the affected and unaffected side of each patient, we concluded there were statistically significant differences (p<0.01) between the 2 groups. Using receiver operating characteristic curve analysis, the cutoff values were calculated to be 15.2 milliseconds and 1.1 milliseconds, respectively.ConclusionsThis approach using a means of DML measurement enables us to identify and localize lesions, which offers an advantage in diagnosing extraforaminal stenosis at L5-S1.

Electroneurography of the ulnar nerve in dogs

Electroneurography as one of the electrodiagnostic techniques is used to measure the speed of action potential which is propagated down the nerve after stimulation. It gives information about normal functioning of the peripheral nerves. The aim of this study was to evaluate the applicability of a new electroneurographic technique by performing motor nerve conduction velocity measurements in the ulnar nerve with surface stimulating electrodes in healthy dogs, to correlate the obtained data by age, limb length, rectal temperature, and sex; and to compare these results with published findings utilizing needle stimulating electrodes. The study was performed in 24 clinically healthy dogs without anaesthesia. Rectal temperatures and limb lengths were measured in all individuals. There were significant correlations among several indicators (age, rectal temperature, limb length, conduction velocity, latency and duration of compound muscle action potentials). Limb length was found to have a significant effect on the duration of the compound muscle action potential from both stimulation sites (proximal/distal; r = 0.71, r = 0.68, P &lt; 0.01), but there was no effect on the conduction velocity or amplitude of the action potentials. There was no significant difference (P &gt; 0.05) in the measured indicators between males and females, even though females had a higher mean conduction velocity than males. These results prove that conduction velocity measurements in dogs could be performed non-invasively, without a danger of infection or haematomas or complications with anaesthesia, which is more favourable and time-saving for clinical practice, and more comfortable for patients.

Chapter 19 - Epidermal innervation in diabetes

The skin is innervated by small sensory and autonomic fibers. In the epidermis, sensory fibers are present as unmyelinated C fibers that terminate as free nerve endings. The determination of epidermal nerve fiber (ENF) density using the immunohistochemical method is a powerful tool that provides insight into a population of nerve fibers that is prominently altered in small fiber neuropathy. The superficial location of epidermal nerve fibers allows repeated sampling of these nerves in a relatively noninvasive fashion, and in sites that cannot be assessed through conventional electrodiagnostic techniques. These features have allowed investigators to diagnose diabetic neuropathy earlier in the course of disease. ENF density holds promise as a biomarker for neuropathic pain and is a sensitive indicator of neuropathic progression. Finally, the ability to injure these fibers in a standardized fashion has led to novel measures of human axonal regeneration that may provide a more sensitive ruler by which to assess promising regenerative compounds in clinical trials.

Which nerve conduction parameters can predict spontaneous electromyographic activity in carpal tunnel syndrome?

ObjectiveWe investigate electrodiagnostic markers to determine which parameters are the best predictors of spontaneous electromyographic (EMG) activity in carpal tunnel syndrome (CTS). MethodsWe enrolled 229 patients with clinically proven and nerve conduction study (NCS)-proven CTS, as well as 100 normal control subjects. All subjects were evaluated using electrodiagnostic techniques, including median distal sensory latencies (DSLs), sensory nerve action potentials (SNAPs), distal motor latencies (DMLs), compound muscle action potentials (CMAPs), forearm median nerve conduction velocities (FMCVs) and wrist–palm motor conduction velocities (W–P MCVs). All CTS patients underwent EMG examination of the abductor pollicis brevis (APB) muscle, and the presence or absence of spontaneous EMG activities was recorded. Normal limits were determined by calculating the means±2 standard deviations from the control data. Associations between parameters from the NCS and EMG findings were investigated. ResultsIn patients with clinically diagnosed CTS, abnormal median CMAP amplitudes were the best predictors of spontaneous activity during EMG examination (p<0.001; OR 36.58; 95% CI 15.85–84.43). If the median CMAP amplitude was ⩽2.1mV, the rate of occurrence of spontaneous EMG activity was >95% (positive predictive rate >95%). If the median CMAP amplitude was higher than the normal limit (>4.9mV), the rate of no spontaneous EMG activity was >94% (negative predictive rate >94%). An abnormal SNAP amplitude was the second best predictor of spontaneous EMG activity (p<0.001; OR 4.13; 95% CI 2.16–7.90), and an abnormal FMCV was the third best predictor (p=0.01; OR 2.10; 95% CI 1.20–3.67). No other nerve conduction parameters had significant power to predict spontaneous activity upon EMG examination. ConclusionsThe CMAP amplitudes of the APB are the most powerful predictors of the occurrence of spontaneous EMG activity. Low CMAP amplitudes are strongly associated with spontaneous activity, whereas high CMAP amplitude are less associated with spontaneous activity, implying that needle EMG examination should be recommended for the detection of spontaneous activity in those CTS patients whose NCS reveals CMAP amplitudes between 2.1mV and the lower normal limit (4.9mV in the present study). SignificanceUsing NCS, electromyographers can predict the presence of spontaneous EMG activity in CTS patients.

SAT0413 Sympathetic Skin Response in Diabetic Patients with Soft Tissue Rheumatism of the Hand

BackgroundMusculoskeletal complications of the hand may be very debilitating for the diabetic patient. The most commonly recognized complications are trigger finger, tenosynovitis, Dupuytren’s contrcture, carpal tunnel syndrome (CTS), and limited...

Emerging Techniques in the Electrodiagnostic Laboratory

Electrodiagnostic techniques have been used for many decades to study neuromuscular diseases. In recent years, we have seen the extension of these methods to study disease progression, complemented by other technologies, for example, ultrasonography. There also is a growing interest in using surface electromyography, which is generally better accepted by patients than needle insertions. This article will discuss these trends and give examples of a few new and emerging methods that have the potential for use in an electrodiagnostic laboratory.

Electrodiagnostic Evaluation of Carpal Tunnel Syndrome and Ulnar Neuropathies

Carpal tunnel syndrome (CTS) and ulnar mononeuropathies at the elbow and wrist are the most common nerve entrapments in the upper extremities. Electrodiagnostic studies are a valid and reliable means of confirming the clinical diagnosis. This review addresses various electrodiagnostic techniques to evaluate the median and ulnar nerves at the wrist and elbow. It also discusses the limitations of electrodiagnostic studies with regard to the sensitivity and specificity of such testing.

Ultrasonography and Electrodiagnosis: Are They Complementary Techniques?

AbstractIn this review, the role of high-resolution ultrasound in the diagnosis of neuromuscular disease as a tool complementary to electrodiagnostic techniques will be discussed, including indications, advantages, limitations, and potential for future research. Ultrasound-guided needle placement can be used to increase accuracy and safety of nerve conduction studies and needle electromyography. Ultrasound imaging of nerve and muscle can provide additional diagnostic information when performed in conjunction with nerve conduction studies and needle electromyography in the setting of nerve entrapment, nerve inflammation, and muscle disease. Its unique features include the ability to image structures dynamically in real time and the technique of sonopalpation. Because neuromuscular ultrasound is a rapidly evolving diagnostic tool with significant changes in technology, which facilitates its increased use, there is a steadily growing body of literature in this area. However, there remains an ongoing need for high-quality studies that evaluate the role and cost-effectiveness of neuromuscular ultrasound, both when used alone and in combination with electrodiagnosis.

T-Reflex Studies in Human Upper Limb Muscles During Voluntary Contraction: Normative Data and Diagnostic Value for Cervical Radiculopathy

ObjectiveTo evaluate the diagnostic utility of the T reflexes elicited from the upper limb muscles during standardized volitional contraction monitored by a real-time integrating electromyographic analyzer. DesignProspective descriptive study. SettingDepartment of orthopedic surgery at a university hospital. ParticipantsHealthy subjects (n=80) evenly distributed across decades of age from 21 to 79 years, and 12 consecutive patients with a single cervical root lesion based on clinical and magnetic resonance imaging studies and diagnostic block. InterventionsNot applicable. Main Outcome MeasuresUsing a special hammer, which externally triggers the sweep on skin contact, we evoked T reflexes in the biceps (C5), brachioradialis (C6), triceps (C7), and the first dorsal interosseous muscles (C8). ResultsSimultaneous regression analyses yielded clinically useful upper limits of normative values for latencies, side-to-side differences, and amplitude ratios adjusted to age and arm span. Comparison of the T reflexes between the 2 sides localized the solitary root lesions with a high sensitivity (92%), specificity (81%), and accuracy (83%). T-reflex studies proved helpful to localize the lesion even in patients who solely complained of upper limb pain. ConclusionsThe T reflexes with a standardized facilitation of the upper limb muscles provide a clinically useful, noninvasive measure to localize the C5 to C8 radiculopathies. This study contributes in reassessing the currently underused T reflex as an electrodiagnostic technique.

128. Single fiber electromyography with a concentric needle electrode and surface stimulus in the orbicularis oculi muscle

arthroscopy 3 months prior, using three standard ankle port sites, subsequently developed precisely delineated numbness and pain of the right ankle and foot. Physical examination showed heterogeneous sensory disturbance and hypersensitivity throughout the entire dorsum of the foot, as well as extensor digitorum brevis atrophy. Electrodiagnosis demonstrated neuropathy of the right saphenous, superficial fibular sensory, and distal deep fibular nerves. High frequency ultrasound was utilized for further localization and assessment. Ultrasonography demonstrated loss of the fasicular architecture and fusiform swelling of the affected nerves precisely at the port sites, but continuity was demonstrated with each nerve. Conclusion: This case demonstrates the utility of high frequency ultrasound in the assessment of traumatic neuropathies. Using this modality provided evidence of continuity (i.e., no neurotmesis) in the nerves that had absent sensory nerve action potentials. It also provided more precise localization of the injury than electrodiagnostic techniques alone. Additionally, this is the first reported case, to the authors’ knowledge, demonstrating ultrasonographic evidence of nerve disruption following a standard ankle arthroscopic procedure.

Thoracic Outlet Syndrome—Postural Type: Ultrasound Imaging of Pectoralis Minor and Brachial Plexus Abnormalities

Thoracic outlet syndrome (TOS) is a controversial diagnosis that sometimes is referred to as disputed or nonspecific neurogenic TOS because diagnostic test results typically are negative or inconclusive [1-10]. A review of the pathomechanics and associated dysfuncional body habitus suggests that use of the term “postural TOS” is more appropriate for this ommon type of presentation [10]. Postural TOS is thus recommended in cases without bjectifiable neurologic or vascular abnormality. In contrast, the less-common type of TOS nvolves compromise of the neurovascular bundle (NVB), which includes the brachial lexus (BP), the axillary or subclavian artery, and the axillary or subclavian vein [1-8,10]. Compression in all types of TOS may occur superiorly at the interscalene space, the costoclavicular space, or beneath the pectoralis minor muscle (PMM). The PMM location is recognized as a common and important site of compression in both the postural and nonpostural types of TOS [1-3,9-13]. The findings on an electrodiagnostic examination (EDX) typically are normal in patients with postural TOS because there is no axonal damage and no significant conduction block or demyelination [1,8,10]. Results of blood-flow studies usually are normal as well, and although they may reveal mild vascular compromise during stress maneuvers [1,2], this finding may not be clinically significant because it also can be seen in asymptomatic persons [1,7-9]. In addition, it is important to consider differential diagnoses and rule out the following conditions: cervical radiculopathy, peripheral nerve entrapment (median or ulnar), peripheral polyneuropathy, cervical cord lesion, or superior sulcus (Pancoast) tumor. The EDX may reveal the first 3 categories, but cervical magnetic resonance imaging (MRI) and a chest radiograph will be needed if the other conditions are considered. Neuromuscular ultrasound (NMUS) is a new imaging modality for examining nerve structures within the thoracic outlet area [14,15]. NMUS has unique applications for the postural type of TOS; as some researchers have noted, “evaluation of proximal nerves is often problematic when using electrodiagnostic techniques and may be more easily studied with ultrasound” [16]. My experience with this type of postural TOS [1,2,9,12,17,18] suggests that the PMM is contributory, and NMUS now appears to support these prior clinical impressions. Palpation of increased tension and trigger points in the PMM, combined with shoulder protraction, suggests that the PMM has shortened. The hypothesis herein is that the effects of a tight PMM can be observed to affect the NVB and explain the symptoms. The goal of this article is to present and analyze imaging findings in patients with TOS who were examined with NMUS while in neutral and stress positions, while monitoring for symptoms.

Comparison Efficacy of Triamcinolone and Wrist Splint in Severe Carpal Tunnel Syndrome in Pregnancy

Introduction: Carpal tunnel syndrome (CTS) is entrapment of median nerve in carpal tunnel of the wrist. The main aim of this study was to compare the effectiveness of steroid injection and wrist splint in severe carpal tunnel syndrome in pregnancy. The cases were selected among pregnant women who referred to OB and GYN clinic in Yasuj city in South- west of Iran. Materials and methods: This study is a randomized clinical trial which was accomplished from December 2010 to June 2012 at S. Mofateh Clinic on 28 pregnant women. Standard electrodiagnostic techniques were performed on the women who had clinical symptoms of CTS in their hands, with positive Tinel and/or Phalen tests, for rule in/or out of CTS. The patients with severe CTS were randomly divided in 2 groups including triamcinolone injection (40 mg) and wrist splint in night for 6 weeks. Electrophysiologic parameters of median and ulnar nerves were recorded before and 2 months after the steroid injection and wrist splint. In cases of observing changes from severe to lower stages of the disease in electrodiagnostic studies, treatment was considered successful and otherwise failed. Results: Effectiveness of triamcinolone injection and wrist splint were 85. 7% and 90. 9%, respectively. There was no significant difference between treatments by steroid injection and wrist splint (p=0. 157). Also no correlation was observed between severe carpal tunnel syndrome and number of pregnancy. Conclusion: Triamcinolone injection or wrist splint are effective methods for treatment of severe CTS in pregnancy and therefore recommended instead of carpal tunnel release surgery.

Tarsal tunnel syndrome: A literature review

Tarsal tunnel syndrome (TTS) is an entrapment neuropathy of the posterior tibial nerve or its branches within its fibro-osseous tunnel beneath the flexor retinaculum on the medial side of the ankle. It is a rare but important condition which is regularly under diagnosed leading to a range of symptoms affecting the plantar aspect of the foot. Management of this entrapment neuropathy remains a challenge and we have therefore reviewed the published literature in an attempt to clarify aspects of initial presentation, investigation and definitive treatment including surgical decompression. We also assessed the continuing controversial role of electrodiagnostic techniques in its diagnosis. Recommendations from literature: Excellent results with decompression in selected patients. To prevent nerve fibrosis, decompression should be performed early. Remain aware of false negative NCS (under-diagnosing of those with symptoms but ‘normal’ NCS. Role of NCS remains controversial with inability to predict which cases respond to decompression. Poor outcome may be due to nerve fibrosis.