Serial electrodiagnostic testing: Utility and indications in adult neurological disorders

Although existing guidelines address electrodiagnostic (EDX) testing in identifying neuromuscular conditions, guidance regarding the uses and limitations of serial (or repeat) EDX testing is limited. By assessing neurophysiological change longitudinally across time, serial electrodiagnosis can clarify a diagnosis and potentially provide valuable prognostic information. This monograph presents four broad indications for serial electrodiagnosis in adult peripheral neurological disorders. First, where clinical change has raised suspicion for a new or ongoing lesion, EDX reassessment for spatial spread of abnormality, involvement of previously normal muscle or nerve, and/or evolving pathophysiology can clarify a diagnosis. Second, where diagnosis of a progressive neuromuscular condition is uncertain, electrophysiological data from a second time point can confirm or refute suspicion. Third, to establish prognosis after a static nerve injury, a repeat study can assess the presence and extent of reinnervation. Finally, faced with a limited initial study (as when complicated by patient or environmental factors), a repeat EDX study can supplement missing or limited data to provide needed clarity. Repeat EDX studies carry certain limitations, however, such as with prognostication in the setting of remote or chronic lesions, sensory predominant fascicular injury, or mild axonal injury. Nevertheless, serial electrodiagnosis remains a valuable and underused tool in the diagnostic and prognostic evaluation of neuromuscular conditions.

Electrodiagnostic studies and new diagnostic modalities for evaluation of peripheral nerve disorders

Electrodiagnostic studies (EDx) are frequently performed in the diagnostic evaluation of peripheral nerve disorders. There is increasing interest in the use of newer, alternative diagnostic modalities, in particular imaging, either to complement or replace established EDx protocols. However, the evidence to support this approach has not been expansively reviewed. In this paper, diagnostic performance data from studies of EDx and other diagnostic modalities in common peripheral nerve disorders have been analyzed and described, with a focus on radiculopathy, plexopathy, compressive neuropathies, and the important neuropathy subtypes of Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), vasculitic neuropathy and diabetic neuropathy. Overall EDx retains its place as a primary diagnostic modality in the evaluated peripheral nerve disorders. Magnetic resonance imaging and ultrasound have developed important complementary diagnostic roles in compressive and traumatic neuropathies and atypical CIDP, but their value is more limited in other neuropathy subtypes. Identification of hourglass constriction in nerves of patients with neuralgic amyotrophy may have therapeutic implications. Investigation of radiculopathy is confounded by poor correlation between clinical features and imaging findings and the lack of a diagnostic gold standard. There is a need to enhance the literature on the utility of these newer diagnostic modalities.

Clinical and Electrophysiological Characteristics of Very Early Guillain-Barré Syndrome

PURPOSE

This study compared the clinical and electrodiagnostic (EDX) features and long-term outcomes of patients with very early Guillain-Barré syndrome (VEGBS, duration of illness ≤4 days) and those with early/late (>4 days)-presenting GBS.

METHODS

One hundred patients with GBS were clinically evaluated and categorized into VEGBS and early/late GBS groups. Electrodiagnostic studies were performed on the bilateral median, ulnar, and fibular motor nerves and the bilateral median, ulnar, and sural sensory nerves. Admission and peak disability were assessed using the 0 to 6 Guillain-Barré Syndrome Disability Scale (GBSDS). The primary outcome was disability at 6 months, which was categorized as complete (GBSDS ≤1) or poor (GBSDS ≥2). The secondary outcomes were frequencies of abnormal electrodiagnostic findings, in-hospital progression, and mechanical ventilation (MV).

RESULTS

Patients with VEGBS had higher peak disability (median 5 vs. 4; P = 0.02), frequent in-hospital disease progression (42.9% vs. 19.0%, P < 0.01), needed MV (50% vs. 22.4%; P < 0.01), and less frequent albuminocytologic dissociation (52.4% vs. 74.1%; P = 0.02) than those with early/late GBS. Thirteen patients were lost to follow-up at 6 months (nine patients with VEGBS and four patients with early/late GBS). The proportion of patients with complete recovery at 6 months was comparable (60.6% vs. 77.8%; P = ns ). Reduced d-CMAP was the most common abnormality, noted in 64.7% and 71.6% of patients with VEGBS and early/late GBS, respectively ( P = ns). Prolonged distal motor latency (≥130%) was more common in early/late GBS than in VEGBS (36.2% vs. 25.4%; P = 0.02), whereas absent F-waves were more frequent in VEGBS (37.7% vs. 28.7%; P = 0.03).

CONCLUSIONS

Patients with VEGBS were more disabled at admission than those with early/late GBS. However, 6 month's outcomes were similar between the groups. F-wave abnormalities were frequent in VEGBS, and distal motor latency prolongation was common in early/late GBS.

Gray-Scale and Power Doppler Ultrasound Findings Predictive of Cubital Tunnel Syndrome Severity

BACKGROUND

The use of ultrasound in the diagnosis of cubital tunnel syndrome (CuTS) is an attractive alternative to electrodiagnostic (EDX) studies, but its utility is binary with poor severity correlation. We hypothesize that increasing ulnar nerve cross-sectional area (CSA) and power Doppler measurement of intraneural vascularity may predict the extent of disease.

METHODS

We identified 20 elbows from patients with a history of CuTS and 20 elbows in 10 asymptomatic controls. Electrodiagnosis was performed for symptomatic patients. Gray-scale ultrasound and power Doppler ultrasound were performed to measure CSA and intraneural vascularity in all participants. Functional measures, Boston Carpal Tunnel Questionnaire (BCTQ), and Patient-Reported Outcomes Measurement Information System surveys were also completed.

RESULTS

A strong positive correlation was found between CSA and motor nerve conduction velocity (MNCV) decrease between elbow and forearm, which increased when BCTQ >2 was used as a screening criterion. Increased CSA also demonstrated a high positive predictive value (PPV) in predicting MNCV changes, but poor ability to predict axonal loss. In contrast, power Doppler ultrasound demonstrated 100% PPV and 94% negative predictive value (NPV) in predicting severe CuTS (defined as compound motor action potential [CMAP] amplitude <6 mV and electromyography [EMG] findings).

CONCLUSIONS

Cross-sectional area is a sensitive method for identifying changes in MNCV and amplitude but does not stratify disease severity, as defined by diminished CMAP amplitude and/or evidence of denervation on EMG. The presence of increased intraneural vascularity is relatively sensitive but highly specific for axonal loss. The combination of nerve CSA, BCTQ screening, and power Doppler ultrasound may provide an alternative means for CuTS assessment.

Distal symmetrical polyneuropathy in diabetes mellitus patients: Proposition of a new scoring system based on electroneurography findings

BACKGROUND

Neuropathy affects 25% of people with diabetes mellitus. The evaluation of disease severity is still a challenge for modern medicine. Many screening instruments are based primarily on clinical criteria. There is a lack of a simple, reliable and precise scoring system that could improve the classification of neuropathy and monitor disease progression using not only clinical criteria but also electroneurography. There is a need to find sensitive neurography parameters that reflect peripheral nerve impairments in this group of patients.

OBJECTIVES

This study aimed to create a scoring system for diabetic neuropathy, based on electroneurography criteria, that reflects the natural course of the disease. A new scoring system will improve the treatment of patients with diabetes mellitus.

MATERIAL AND METHODS

A total of 113 patients with distal symmetrical polyneuropathy (DSPN) were involved in the study. Median, ulnar, sural, tibial, and peroneal nerves were examined. Parameters such as amplitude, conduction velocity, distal latency, and F wave latency were analyzed. The results of nerve conduction studies in the investigated group were compared to those of the control group, which consisted of 61 healthy volunteers.

RESULTS

The most sensitive parameter of peripheral nerve impairment severity was a reduction of the sensory action potential amplitude in the peroneal nerve by 72.8% (p < 0.05). The observation of changes in sensory action potential amplitudes in the peroneal nerve is the most important element of our scoring system.

CONCLUSIONS

A new electroneurography scoring system of DSPN severity should be based on sensory and motor action potential amplitudes that reflect axonal loss in the examined nerves and the nature of the disease.

Electrodiagnostic methods to verify Guillain-Barré syndrome subtypes in Istanbul: A prospective multicenter study

BACKGROUND AND AIMS

This study aimed to identify the clinical characteristics and electrodiagnostic subtypes of Guillain-Barré syndrome (GBS) in Istanbul.

METHODS

Patients with GBS were prospectively recruited between April 2019 and March 2022 and two electrodiagnostic examinations were performed on each patient. The criteria of Ho et al., Hadden et al., Rajabally et al., and Uncini et al. were compared for the differentiation of demyelinating and axonal subtypes, and their relations with anti-ganglioside antibodies were analyzed.

RESULTS

One hundred seventy-seven patients were included, 69 before the coronavirus disease 2019 pandemic (April 2019-February 2020) and 108 during the pandemic (March 2020-March 2022), without substantial changes in monthly frequencies. As compared with the criteria of Uncini et al., demyelinating GBS subtype diagnosis was more frequent according to the Ho et al. and Hadden et al. criteria (95/162, 58.6% vs. 110/174, 63.2% and 121/174, 69.5%, respectively), and less frequent according to Rajabally et al.'s criteria (76/174, 43.7%). Fourteen patients' diagnoses made using Rajabally et al.'s criteria were shifted to the other subtype with the second electrodiagnostic examination. Of the 106 analyzed patients, 22 had immunoglobulin G anti-ganglioside antibodies (14 with the axonal subtype). They had less frequent sensory symptoms (54.5% vs. 83.1%, p = 0.009), a more frequent history of previous gastroenteritis (54.5% vs. 22.9%, p = 0.007), and a more severe disease as compared with those without antibodies.

INTERPRETATION

Serial electrodiagnostic examinations are more helpful for accurate subtype diagnosis of GBS because of the dynamic pathophysiology of the disease. We observed no significant increase in GBS frequency during the pandemic in this metropolis.

Training factors that influence electrodiagnostic medicine knowledge

INTRODUCTION/AIMS

Self-assessment examinations (SAEs) help trainees assess their progress in education. SAEs also provide feedback to training programs as to how factors in training influence examination performance. This study's goal was to examine the relationship between the number of months of training in electrodiagnostic (EDx) medicine, the number of EDx studies during training, and scores on the American Association of Neuromuscular and Electrodiagnostic Medicine SAE.

METHODS

This was a retrospective study of the 2023 AANEM-SAE results. In addition to the examination score, participants were asked approximately how many EDx studies they performed in training and how many months of training they had completed. Analysis included correlation of the examination scores with months of training as well as number of EDx studies. In addition, a multivariate linear regression model was developed.

RESULTS

A total of 756 participants completed the proctored examination in May 2023. Examination score was moderately and positively correlated with the number of months of training (Pearson r = .5; p < .001) as well as the number of EDx studies during training (Pearson r = .55; p < .001). Scores steadily improved with additional months of training, but leveled off after 300-400 EDx studies. Regression analysis indicated that higher numbers of EDx studies were correlated with a higher examination score even after accounting for the number of months of study.

DISCUSSION

We believe that a greater number of months of training is associated with better performance on the AANEM-SAE and that greatest improvement in examination performance occurs during the first 300-400 EDx studies.

A review of electromyography techniques of the cervical paraspinal muscles

Electrodiagnosis for cervical radiculopathy often involves exploration of the cervical paraspinal muscles. Accurate and reproducible results require a technique with specific anatomic localization, direction of insertion, extent of insertion, scoring system for insertion, and criteria for determining abnormality. We sought to understand if a published technique met these criteria. A Medline search found 39 articles with original research and 10 review articles involving the cervical paraspinals. A library search found 19 textbooks since 2000, but 9 were not available. Only two studies were specific to the question. Neither had reproducible techniques and they contradicted each other. Studies in which the paraspinals were used for comparison or inclusion did not provide any specific technique. The review articles and textbooks typically met none of our criteria and the few that discussed technique at all provided no reproducible methods. Despite 80 years of electrodiagnostic testing, there is no useful, reproducible technique for exploring the cervical paraspinal muscles. Yet such a paraspinal mapping technique has proven invaluable in the lumbar region. For cervical electromyography to be of value, the next step is to understand the anatomy and propose a reproducible technique. Subsequent research will determine whether the neck muscles are helpful in the diagnosis of cervical radiculopathy. The absence of a valid reproducible cervical paraspinal technique impedes clinical and scientific understanding of cervical radiculopathy.

The role of electrodiagnosis in focal neuropathies

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

Sciatic and tibial neuropathies

The sciatic nerve is the body's largest peripheral nerve. Along with their two terminal divisions (tibial and fibular), their anatomic location makes them particularly vulnerable to trauma and iatrogenic injuries. A thorough understanding of the functional anatomy is required to adequately localize lesions in this lengthy neural pathway. Proximal disorders of the nerve can be challenging to precisely localize among a range of possibilities including lumbosacral pathology, radiculopathy, or piriformis syndrome. A correct diagnosis is based upon a thorough history and physical examination, which will then appropriately direct adjunctive investigations such as imaging and electrodiagnostic testing. Disorders of the sciatic nerve and its terminal branches are disabling for patients, and expert assessment by rehabilitation professionals is important in limiting their impact. Applying techniques established in the upper extremity, surgical reconstruction of lower extremity nerve dysfunction is rapidly improving and evolving. These new techniques, such as nerve transfers, require electrodiagnostic assessment of both the injured nerve(s) as well as healthy, potential donor nerves as part of a complete neurophysiological examination.

Ulnar neuropathy

Ulnar neuropathy at the elbow is the second most common compressive neuropathy. Less common, although similarly disabling, are ulnar neuropathies above the elbow, at the forearm, and the wrist, which can present with different combinations of intrinsic hand muscle weakness and sensory loss. Electrodiagnostic studies are moderately sensitive in diagnosing ulnar neuropathy, although their ability to localize the site of nerve injury is often limited. Nerve imaging with ultrasound can provide greater localization of ulnar injury and identification of specific anatomical pathology causing nerve entrapment. Specifically, imaging can now reliably distinguish ulnar nerve entrapment under the humero-ulnar arcade (cubital tunnel) from nerve injury at the retro-epicondylar groove. Both these pathologies have historically been diagnosed as either "ulnar neuropathy at the elbow," which is non-specific, or "cubital tunnel syndrome," which is often erroneous. Natural history studies are few and limited, although many cases of mild-moderate ulnar neuropathy at the elbow appear to remit spontaneously. Conservative management, perineural steroid injections, and surgical release have all been studied in treating ulnar neuropathy at the elbow. Despite this, questions remain about the most appropriate management for many patients, which is reflected in the absence of management guidelines.

The role of imaging in focal neuropathies

Electrodiagnostic testing (EDX) has been the diagnostic tool of choice in peripheral nerve disease for many years, but in recent years, peripheral nerve imaging has been used ever more frequently in daily clinical practice. Nerve ultrasound and magnetic resonance (MR) neurography are able to visualize nerve structures reliably. These techniques can aid in localizing nerve pathology and can reveal significant anatomical abnormalities underlying nerve pathology that may have been otherwise undetected by EDX. As such, nerve ultrasound and MR neurography can significantly improve diagnostic accuracy and can have a significant effect on treatment strategy. In this chapter, the basic principles and recent developments of these techniques will be discussed, as well as their potential application in several types of peripheral nerve disease, such as carpal tunnel syndrome (CTS), ulnar neuropathy at the elbow (UNE), radial neuropathy, brachial and lumbosacral plexopathy, neuralgic amyotrophy (NA), fibular, tibial, sciatic, femoral neuropathy, meralgia paresthetica, peripheral nerve trauma, tumors, and inflammatory neuropathies.

Axillary and musculocutaneous neuropathies

This chapter covers axillary and musculocutaneous neuropathies, with a focus on clinically relevant anatomy, electrodiagnostic approaches, etiologic considerations, and management principles. Disorders of the lateral antebrachial cutaneous nerve, a derivative of the musculocutaneous nerve, are also reviewed. We emphasize the importance of objective findings, including the physical examination and electrodiagnostic evaluation in confirming the isolated involvement of each nerve which, along with the clinical history, informs etiologic considerations. Axillary and musculocutaneous neuropathies are both rare in isolation and most frequently occur in the setting of trauma. Less commonly encountered etiologies include external compression or entrapment, neoplastic involvement, or immune-mediated disorders including neuralgic amyotrophy, postsurgical inflammatory neuropathy, multifocal motor neuropathy, vasculitic neuropathy, and multifocal chronic inflammatory demyelinating polyradiculoneuropathy.

A Three months Electrodiagnostic Follow-Up of Patients Suspected of having Ulnar Nerve Involvement at Elbow Level with Normal Conventional Electrodiagnostic Study at First Evaluation

BACKGROUND

Compression of ulnar nerve at the elbow is the second most common peripheral neuropathy of the upper extremity.

OBJECTIVE

Due to the lack of the gold diagnostic standard for ulnar nerve involvement at elbow level (UNE) and the lack of sufficient study in this field, we decided to evaluate patients with symptoms of this disease who have normal conventional electrodiagnostic study (EDX) in first evaluation.

MATERIALS AND METHODS

In this cross-sectional study, 18 persons were selected from patients who were referred to the clinic of Physical Medicine and Rehabilitation. If conventional EDX was normal, compound nerve action potential (CNAP) test (peak latency and amplitude) was carried out. Patients with normal conventional EDX but abnormal ulnar CNAP included to our study. After 3 months, if they had not been treated for ulnar neuropathy, they were reexamined by conventional EDX plus ulnar CNAP measurement.

RESULTS

In total, 18 patients (11 females, 7 males) aged 28-58 years old (mean = 40.11) were analyzed in this study. After 3 months, 14 patients (77.8%) demonstrated parameter changes consistent with UNE in conventional EDX.

CONCLUSION

Based on the results of this study, ulnar CNAP has diagnostic value in patients with symptoms of UNE who have normal routine EDX. Therefore, ulnar CNAP should be taken into account for early diagnosis of ulnar neuropathy when routine electrodiagnostic tests are normal.

Electrodiagnosis of Guillain-Barre syndrome in the International GBS Outcome Study: Differences in methods and reference values

OBJECTIVE

To describe the heterogeneity of electrodiagnostic (EDx) studies in Guillain-Barré syndrome (GBS) patients collected as part of the International GBS Outcome Study (IGOS).

METHODS

Prospectively collected clinical and EDx data were available in 957 IGOS patients from 115 centers. Only the first EDx study was included in the current analysis.

RESULTS

Median timing of the EDx study was 7 days (interquartile range 4-11) from symptom onset. Methodology varied between centers, countries and regions. Reference values from the responding 103 centers were derived locally in 49%, from publications in 37% and from a combination of these in the remaining 15%. Amplitude measurement in the EDx studies (baseline-to-peak or peak-to-peak) differed from the way this was done in the reference values, in 22% of motor and 39% of sensory conduction. There was marked variability in both motor and sensory reference values, although only a few outliers accounted for this.

CONCLUSIONS

Our study showed extensive variation in the clinical practice of EDx in GBS patients among IGOS centers across the regions.

SIGNIFICANCE

Besides EDx variation in GBS patients participating in IGOS, this diversity is likely to be present in other neuromuscular disorders and centers. This underlines the need for standardization of EDx in future multinational GBS studies.

Focal Peripheral Neuropathies Observed in Patients Diagnosed With COVID-19: A Case Series

ABSTRACT

A growing number of studies have documented a wide variety of neurological manifestations associated with the novel SARS-CoV-2 (COVID-19). Of the available literature, cranial neuropathies and central nervous system disorders, such as encephalopathy and ischemic strokes, remain the predominant discussion. Limited investigations exist examining peripheral neuropathies of those with COVID-19. This case series discusses eight patients who tested positive for COVID-19 and presented with localized weakness after a prolonged course of mechanical ventilation (>21 days). We retrospectively reviewed all patients' charts who received electrodiagnostic evaluation between March and November 2020 in the outpatient clinic or in the acute care hospital at the JFK Medical Center/JFK Johnson Rehabilitation Institute and Saint Peter's University Hospital of New Jersey. A total of eight COVID-19-positive patients were identified to have a clinical presentation of localized weakness after a prolonged course of mechanical ventilation. All patients were subsequently found to have a focal peripheral neuropathy of varying severity that was confirmed by electrodiagnostic testing. Patient demographics, clinical, and electrodiagnostic findings were documented. The findings of local weakness and focal peripheral neuropathies after diagnosis of COVID-19 raise significant questions regarding underlying pathophysiology and overall prognosis associated with COVID-19.

Neuromuscular Ultrasound: Indications in the Electrodiagnostic Laboratory

ABSTRACT

Accurate assessment of neuromuscular disorders is critical to facilitate timely treatment and achieve the best outcomes. Historically, electrodiagnostic studies have filled this role, but recently, neuromuscular ultrasound is being used in the electrodiagnostic laboratory. This review discusses the uses of neuromuscular ultrasound in the electrodiagnostic laboratory that have strong evidence, emphasizing those that could be adopted in a typical electrodiagnostic laboratory with a reasonable level of equipment and training. The evidence currently supports using neuromuscular ultrasound to diagnose carpal tunnel syndrome and ulnar neuropathies at the elbow and as a supplementary test when electrodiagnostic studies are suspected to be falsely negative or in axonal nonlocalizing lesions. Neuromuscular ultrasound can identify the causes of focal mononeuropathies, which can change treatment in specific cases. It is sensitive at identifying fasciculations and providing complementary evidence of autoimmune demyelinating polyneuropathies. It is particularly helpful in assessing nerves after trauma. Neuromuscular ultrasound is likely to prove even more useful in the electrodiagnostic laboratory as the technology continues to advance.

Prevalence and predictive factors for bilateral carpal tunnel syndrome by electrodiagnosis: A retrospective study

Introduction

Carpal tunnel syndrome (CTS) is the most common compressive neuropathy. Patients who have unilateral symptoms are frequently found to have bilateral CTS by electrodiagnostic (EDx) study. We aimed to (a) study the prevalence and identify the predictive factors for bilateral CTS diagnosed by EDx; and (b) develop a model to predict bilateral CTS.

Methods

The retrospective clinical and EDx data of patients with CTS were collected and analyzed using the Chi-squared test and multiple logistic regression analysis. A model was fitted, and the best cutoff point determined. Calibration and discrimination performance of the model were performed.

Results

A total of 327 patients with a mean age of 50.0 years were enrolled. Most were women (82.6%), and the most common presenting symptom was hand numbness (93.6%). The median duration of symptoms was 60 days. The prevalence of bilateral CTS was 80.7%. In the multivariate analysis, the predictive factors for bilateral CTS were the presence of bilateral symptoms (AOR 6.7 [95%CI 3.1–14.3]), thenar muscle weakness (AOR 3.9 [95%CI 1.3–11.6]), and age ≥ 45 years (AOR 2.5 [95%CI 1.3–4.6]). The logistic regression model was fitted, and the best cutoff point determined. The area under the receiver operating curve (AUC) was 0.76. The respective optimism-corrected C index and Somers’ D was 0.762 and 0.524.

Conclusion

The prevalence of bilateral CTS was 80.7%. Our findings suggest bilateral CTS was predicted with adequate diagnostic accuracy by bilateral symptoms, age ≥ 45 years, and thenar muscle weakness.

Utility of shear wave elastography and high-definition color for diagnosing carpal tunnel syndrome

OBJECTIVE

The diagnostic values of measuring median nerve (MN) stiffness and vascularity with shear wave elastography (SWE) and high-definition (HD) color were investigated in carpal tunnel syndrome (CTS).

METHODS

Seventy patients (123 wrists) with CTS and thirty-five healthy volunteers (70 wrists) were enrolled. Based on nerve conduction studies (NCS), the patients were subdivided into NCS-negative, mild-to-moderate, and severe CTS groups. MN and abductor pollicis brevis (APB) SWE and MN HD color were performed on a longitudinal plane.

RESULTS

The mild-to-moderate and severe CTS groups showed increased MN stiffness at the wrist and MN stiffness ratio (wrist-to forearm) compared with the control (p < 0.001). The NCS-negative CTS group showed increased MN stiffness at the wrist (p = 0.022) and MN stiffness ratio (p = 0.032) compared with the control. The severe CTS group showed increased MN stiffness at the wrist compared with the mild-to-moderate CTS group (p = 0.034). The cutoff-values in diagnosing NCS-confirmed CTS were 50.12 kPa for MN stiffness at the wrist, 1.91 for MN stiffness ratio, and grade 1 for HD color.

CONCLUSIONS

SWE and HD color are good supportive tools in diagnosing and assessing severity in CTS.

SIGNIFICANCE

SWE and HD color demonstrated that MN in CTS was associated with increased stiffness and hypervascularity.

Characterization of mononeuropathy of the lateral cutaneous nerve of the calf

INTRODUCTION/AIMS

Isolated injuries to the lateral cutaneous nerve of the calf (LCNC) branch of the common peroneal nerve can cause obscure chronic posterolateral knee and upper calf pain and sensory symptoms. Routine examination and electrodiagnostic testing do not detect them because the LCNC has no motor distribution and it is not interrogated by the typical peroneal nerve conduction study. There are only about 10 prior cases, thus scant physician awareness, so most LCNC injuries remain misdiagnosed or undiagnosed, hindering care.

METHODS

We extracted pertinent records from seven patients with unexplained posterolateral knee/calf pain, six labeled as complex regional pain syndrome, to investigate for mononeuropathies. Patients were asked to outline their skin area with abnormal responses to pin self-examination independently. Three underwent an LCNC-specific electrodiagnostic study, and two had skin-biopsy epidermal innervation measured. Cadaver dissection of the posterior knee nerves helped identify potential entrapment sites.

RESULTS

Initiating events included knee surgery (three), bracing (one), extensive kneeling (one), and other knee trauma. All pin-outlines included the published LCNC neurotome. One oftwo LCNC-specific electrodiagnostic studies revealed unilaterally absent potentials. Longitudinal, controlled skin biopsies documented profound LCNC-neurotome denervation then re-innervation contemporaneous with symptom recovery. Cadaver dissection identified the LCNC traversing through the dense fascia of the proximolateral gastrocnemius muscle insertion.

DISCUSSION

Isolated LCNC mononeuropathy can cause unexplained posterolateral knee/calf pain syndromes. This series characterizes presentations and supports patient pin-mappings as a sensitive, globally available, low-cost diagnostic aid. Improved recognition may facilitate more rapid, accurate diagnosis and, thus, optimize management and improve outcomes.

Machine learning powered tools for automated analysis of muscle sympathetic nerve activity recordings

Automated analysis and quantification of physiological signals in clinical practice and medical research can reduce manual labor, increase efficiency, and provide more objective, reproducible results. To build a novel platform for the analysis of muscle sympathetic nerve activity (MSNA), we employed state-of-the-art data processing and machine learning applications. Data processing methods for integrated MSNA recordings were developed to evaluate signals regarding the overall quality of the signal, the validity of individual signal peaks regarding the potential to be MSNA bursts and the timing of their occurrence. An overall probability score was derived from this flexible platform to evaluate each individual signal peak automatically. Overall, three deep neural networks were designed and trained to validate individual signal peaks randomly sampled from recordings representing only electrical noise and valid microneurography recordings. A novel data processing method for the whole signal was developed to differentiate between periods of valid MSNA signal recordings and periods in which the signal was not available or lost due to involuntary movement of the recording electrode. A probabilistic model for timing of the signal bursts was implemented as part of the system. Machine Learning algorithms and data processing tools were implemented to replicate the complex decision-making process of manual MSNA analysis. Validation of manual MSNA analysis including intra- and inter-rater validity and a comparison with automated MSNA tools is required. The developed toolbox for automated MSNA analysis can be extended in a flexible way to include algorithms based on other datasets.

All-printed stretchable corneal sensor on soft contact lenses for noninvasive and painless ocular electrodiagnosis

Electroretinogram examinations serve as routine clinical procedures in ophthalmology for the diagnosis and management of many ocular diseases. However, the rigid form factor of current corneal sensors produces a mismatch with the soft, curvilinear, and exceptionally sensitive human cornea, which typically requires the use of topical anesthesia and a speculum for pain management and safety. Here we report a design of an all-printed stretchable corneal sensor built on commercially-available disposable soft contact lenses that can intimately and non-invasively interface with the corneal surface of human eyes. The corneal sensor is integrated with soft contact lenses via an electrochemical anchoring mechanism in a seamless manner that ensures its mechanical and chemical reliability. Thus, the resulting device enables the high-fidelity recording of full-field electroretinogram signals in human eyes without the need of topical anesthesia or a speculum. The device, superior to clinical standards in terms of signal quality and comfortability, is expected to address unmet clinical needs in the field of ocular electrodiagnosis.

Prolonged median distal sensory nerve action potential duration in carpal tunnel syndrome

OBJECTIVE

Routine nerve conduction study (NCS) parameters are less sensitive in the early stage of carpal tunnel syndrome (CTS). Recently, some studies have shown that prolonged distal sensory nerve action potential (DSNAP) duration may be a more sensitive technique for the diagnosis of demyelinating peripheral neuropathies. We aimed to evaluate the sensitivity of median DSNAP duration in patients with CTS.

METHODS

DSNAP duration and routine NCS data of the median nerve were retrospectively collected in 173 CTS patients, 73 controls, and 78 cervical radiculopathy patients.

RESULTS

Prolonged median DSNAP durations were found in 22 patients (22/35, 63%) and 36 patients (36/54, 67%) in the minimal and mild CTS groups respectively, which was more sensitive than routine NCS parameters. The percentage of patients demonstrating abnormalities in median NCS was significantly increased from 80% to 92% with the addition of DSNAP duration.

CONCLUSION

Our results demonstrate the electrodiagnostic value of median DSNAP duration for the diagnosis of CTS, especially in early cases.

Electrogastrography for psychophysiological research: Practical considerations, analysis pipeline, and normative data in a large sample

Electrogastrography (EGG) is the noninvasive electrophysiological technique used to record gastric electrical activity by means of cutaneous electrodes placed on the abdomen. EGG has been so far mostly used in clinical studies in gastroenterology, but it represents an attractive method to study brain-viscera interactions in psychophysiology. Compared to the literature on electrocardiography for instance, where practical recommendations and normative data are abundant, the literature on EGG in humans remains scarce. The aim of this article is threefold. First, we review the existing literature on the physiological basis of the EGG, pathways of brain-stomach interactions, and experimental findings in the cognitive neuroscience and psychophysiology literature. We then describe practical issues faced when recording the EGG in young healthy participants, from data acquisition to data analysis, and propose a semi-automated analysis pipeline together with associated MATLAB code. The analysis pipeline aims at identifying a regular rhythm that can be safely attributed to the stomach, through multiple steps. Finally, we apply these recording and analysis procedures in a large sample (N = 117) of healthy young adult male and female participants in a moderate (<5 hr) to prolonged (>10 hr) fasting state to establish the normative distribution of several EGG parameters. Our results are overall congruent with the clinical gastroenterology literature, but suggest using an electrode coverage extending to lower abdominal locations than current clinical guidelines. Our results indicate a marginal difference in EGG peak frequency between male and female participants, and that the gastric rhythm becomes more irregular after prolonged fasting.

Power Efficiency Comparison of Event-Driven and Fixed-Rate Signal Conversion and Compression for Biomedical Applications

Energy-constrained biomedical recording systems need power-efficient data converters and good signal compression in order to meet the stringent power consumption requirements of many applications. In literature today, typically a SAR ADC in combination with digital compression is used. Recently, alternative event-driven sampling techniques have been proposed that incorporate compression in the ADC, such as level-crossing A/D conversion. This paper describes the power efficiency analysis of such level-crossing ADC (LCADC) and the traditional fixed-rate SAR ADC with simple compression. A model for the power consumption of the LCADC is derived, which is then compared to the power consumption of the SAR ADC with zero-order hold (ZOH) compression for multiple biosignals (ECG, EMG, EEG, and EAP). The LCADC is more power efficient than the SAR ADC up to a cross-over point in quantizer resolution (for example 8 bits for an EEG signal). This cross-over point decreases with the ratio of the maximum to average slope in the signal of the application. It also changes with the technology and design techniques used. The LCADC is thus suited for low to medium resolution applications. In addition, the event-driven operation of an LCADC results in fewer data to be transmitted in a system application. The event-driven LCADC without timer and with single-bit quantizer achieves a reduction in power consumption at system level of two orders of magnitude, an order of magnitude better than the SAR ADC with ZOH compression. At system level, the LCADC thus offers a big advantage over the SAR ADC.

Acupuncture for Carpal Tunnel Syndrome: A Randomized Controlled Trial Studying Changes in Clinical Symptoms and Electrodiagnostic Tests

BACKGROUND

Carpal tunnel syndrome (CTS) is the most frequent entrapment neuropathy in humans. Nonsurgical management is still a matter of debate, and conservative treatments include splinting, local steroid injections, ultrasound, and oral steroids. Acupuncture and electroacupuncture therapy for symptomatic CTS may improve symptoms and aid nerve repair as well as improve sensory and motor functions. However, limited evidence based on comprehensive evaluation methods is available regarding the effects of those treatments.

OBJECTIVE

The study intended to compare the short-term effects of acupuncture and conventional medical treatment on CTS patients' clinical symptoms and on the results of their electrodiagnostic tests.

DESIGN

The research team designed a randomized controlled trial.

SETTING

The study took place at the electrodiagnostic clinic of the School of Persian and Complementary Medicine at Mashhad University of Medical Sciences (Mashhad, Iran).

PARTICIPANTS

Participants were 60 patients at the clinic with the clinical diagnosis of CTS.

INTERVENTIONS

Participants were randomly assigned to 1 of 2 groups. Patients in the control group received 100 mg of Celebrex as tablets, 2 times daily. Patients in the intervention group received 12 sessions of acupuncture, each for 30 min, for 4 wk. The needle insertion points were fixed for all sessions. In addition, wrist braces were provided to wear at night for 1 mo in both groups.

OUTCOME MEASURES

At baseline, postintervention at the end of week 4, and at a 3-mo follow-up at the end of week 16, participants' clinical symptoms-pain, numbness, tingling, weakness/clumsiness, and night awakenings-and the results of their electrodiagnostic studies were evaluated and compared.

RESULTS

In total, 49 patients completed the study-24 in the control group and 25 in the intervention group. Compared with the control group, the intervention group's clinical symptoms-pain, numbness, tingling, and muscular weakness-based on the subscales of the global symptoms score questionnaire as well as the overall score on that questionnaire improved significantly (P < .05). Regarding the electrodiagnostic studies, only the distal motor latency showed a significantly greater decrease in the acupuncture group in comparison to controls (P = .001).

CONCLUSION

All clinical symptoms and the results of the electrodiagnostic tests improved significantly in the intervention group, and the improvements continued during the 3 mo postintervention. The therapeutic results of acupuncture were mostly similar to and in certain cases better than those of the conventional medical treatment. Therefore, acupuncture can be suggested as a safe and suitable therapeutic method in CTS.

Utility of preoperative electrophysiological testing of the facial nerve in patients with vestibular schwannoma

Purpose

The aim of this study was to analyze the utility of various preoperative electrophysiological tests of the facial nerve CNVII in predicting CNVII function after vestibular schwannoma surgery.

Methods

This retrospective study included 176 patients who had preoperative facial nerve electroneurography and electrically evoked blink reflex testing. We defined the following variables: axonal degeneration of CNVII (AD-CNVII), trigeminal nerve damage (D-CNV), disturbances in the short-latency pathway of the blink reflex (D-BR), and any changes in electrophysiological test results (A-EMG).

Results

AD-CNVII, D-CNV, D-BR, and A-EMG were noted in 24%, 10%, 64%, and 71% of the patients, respectively. Negative D-CNV correlated with good CNVII function in early (p = 0.005) and long-term follow-up (p = 0.003) but was not an independent prognostic factor for postoperative facial muscles function. D-CNV appeared to be closely related to tumor size. D-BR was related to tumor size and had no predictive value. AD-CNVII (amplitude reduction of 50% or more compared to the healthy side) was an independent factor associated with increased risk of facial muscles weakness (p = 0.015 and p = 0.031 for early and late outcomes, respectively).

Conclusions

Further studies are needed to establish which tests and cut-off values are the most useful for predicting post-surgical facial nerve function.

Quantitative electrodiagnostic patterns of damage and recovery after spinal cord injury: a pilot study

Study design

Prospective observational pilot study.

Objectives

To compare quantitative electromyographic (EMG), imaging and strength data at two time points in individuals with cervical spinal cord injury (SCI).

Setting

SCI center, Veterans Affairs Health Care System, Palo Alto, California, USA.

Methods

Subjects without suspected peripheral nerve injury were recruited within 3 months of injury. Needle EMG examination was performed in myotomes above, at, and below the SCI level around 11- and 12-months post injury. EMG data were decomposed using custom software into constituent motor unit trains and each distinct motor unit was analyzed for firing rate and amplitude. Strength measurements were made with dynamometry and according to the International Standard of Neurologic Classification of SCI (ISNCSCI). Cervical magnetic resonance images (MRI) were evaluated by two neuroradiologists for gray and white matter damage around the SCI. Here, we compare the EMG, strength, and imaging findings of the one of the four participants who completed both 3- and 12-month EMG evaluations.

Results

There was an increase in force generation in all muscles tested at 1 year. Localized findings of very fast firing motor units helped localize spinal cord damage and revealed gray matter damage in spinal segments where MRI was normal. Meanwhile, improvement in strength over time corresponded with different electrophysiologic patterns.

Conclusions

Electromyographic decomposition at two time points provides valuable information about localization of spinal cord damage, integrity of motor neuron pools and may provide a unique understanding of neural recovery mechanisms.

Bipolar disorder in the balance

Bipolar disorder (BD) is a severe mood disorder that lacks established electrophysiological, neuroimaging or biological markers to assist with both diagnosis and monitoring disease severity. This study's aim is to describe the potential of new neurophysiological features assistive in BD diagnosis and severity measurement utilizing the recording of electrical activity from the outer ear canal called Electrovestibulography (EVestG). From EVestG data sensory vestibulo-acoustic features were extracted from a single supine-vertical translation stimulus to distinguish 50 depressed and partly remitted/remitted bipolar disorder patients [18 symptomatic (BD-S, MADRS > 19), 32 reduced symptomatic (BD-R, MADRS ≤ 19)] and 31 age and gender matched healthy individuals (controls). Six features were extracted from the measured firing pattern interval histogram and the extracted shape of the average field potential response. Five of the six features had low but significant correlations (p < 0.05) with the MADRS assessment. Using leave-one-out-cross-validation, unbiased parametric and non-parametric classification routines resulted in 75-79%, 84-86%, 76-85% and 79-82% accuracy for separation of control from BD, BD-S and BD-R as well as BD-S from BD-R groups, respectively. The main limitation of this study was the inability to fully disentangle the impact of prescribed medication from the responses recorded. A mix of stationary and movement evoked EVestG features produced good discrimination between control and BD patients whether BD-S or BD-R. Moreover, BD-S and BD-R appear to have measurably different pathophysiological manifestations. The firing pattern features used were dissimilar to those observed in a prior major depressive disorder study.

Validity and reliability of a point-of-care nerve conduction device in diabetes patients

AIMS/INTRODUCTION

Although nerve conduction study (NCS) using a standard electromyography system (EMGS) is considered to be the gold standard in evaluating diabetic polyneuropathy, this examination requires expensive equipment and well-trained technicians. We aimed to validate a point-of-care device, NC-stat/DPNCheck™, that has been developed for widespread use of NCS in diabetic polyneuropathy.

MATERIALS AND METHODS

Diabetes patients underwent two kinds of NCS: DPNCheck™ and electromyography system. Inter-/intrarater reliability of DPNCheck™ were also determined by the intraclass correlation coefficient.

RESULTS

A total of 57 patients were evaluated. The parameters of NCS between the two methods correlated well (r = 0.7734 for the sural nerve conduction velocity, r = 0.6155 for the amplitude of sural nerve action potential). The intraclass correlation coefficients were excellent (intrarater: the velocity 0.767, the amplitude 0.811; interrater: the velocity 0.974, the amplitude 0.834).

CONCLUSIONS

The point-of-care device has excellent reproducibility and good agreement with standard electromyography system. The device might be useful to evaluate diabetic polyneuropathy.

An Electrical Model of Hydrocephalus Shunt Incorporating the CSF Dynamics

The accumulation of cerebrospinal fluid (CSF) in brain ventricles and subarachnoid space is known as hydrocephalus. Hydrocephalus is a result of disturbances in the secretion or absorption process of CSF. A hydrocephalus shunt is an effective method for the treatment of hydrocephalus. In this paper, at first, the procedures of secretion, circulation, and absorption of CSF are studied and subsequently, the mathematical relations governing the pressures in different interacting compartments of the brain are considered. A mechanical-electrical model is suggested based on the brain physiology and blood circulation. In the proposed model, hydrocephalus is modeled with an incremental resistance (Ro) and hydrocephalus shunt, which is a low resistance path to drain the accumulated CSF in the brain ventricles, is modeled with a resistance in series with a diode. At the end, the simulation results are shown. The simulation results can be used to predict the shunt efficiency in reducing CSF pressure and before a real shunt implementation surgery is carried out in a patient's body.

Deep peroneal nerve palsy after opening wedge high tibial osteotomy: A case report

RATIONALE

Peroneal nerve injury is one of the major complications that may occur after closing wedge high tibial osteotomy (CWHTO). In contrast, the reduced risk of the peroneal nerve injury has been considered as one of the advantages of opening wedge HTO (OWHTO).

PATIENT CONCERNS

A 61-year-old male who underwent OWHTO showed a dropped big toe immediately after surgery.

DIAGNOSIS

Injury of deep peroneal nerve was confirmed by electrodiagnostic study. It was probably caused by a posterolaterally protruded screw.

INTERVENTIONS

The protruded screw was replaced with a shorter one 3 weeks after OWHTO.

OUTCOMES

The motor weakness and sensory reduction were completely recovered at 9 months after surgery.

LESSONS

OWHTO has been known to be safe from peroneal nerve injury. However, considering the anatomical course of deep peroneal nerve, great care should be taken to avoid damage to the deep peroneal nerve while drilling holes and inserting distal screws toward the posterolateral aspect of the proximal tibia.

The Ussing chamber system for measuring intestinal permeability in health and disease

BACKGROUND

The relationship between intestinal epithelial integrity and the development of intestinal disease is of increasing interest. A reduction in mucosal integrity has been associated with ulcerative colitis, Crohn's disease and potentially could have links with colorectal cancer development. The Ussing chamber system can be utilised as a valuable tool for measuring gut integrity. Here we describe step-by-step methodology required to measure intestinal permeability of both mouse and human colonic tissue samples ex vivo, using the latest equipment and software. This system can be modified to accommodate other tissues.

METHODS

An Ussing chamber was constructed and adapted to support both mouse and human tissue to measure intestinal permeability, using paracellular flux and electrical measurements. Two mouse models of intestinal inflammation (dextran sodium sulphate treatment and T regulatory cell depletion using C57BL/6-FoxP3DTR mice) were used to validate the system along with human colonic biopsy samples.

RESULTS

Distinct regional differences in permeability were consistently identified within mouse and healthy human colon. In particular, mice showed increased permeability in the mid colonic region. In humans the left colon is more permeable than the right. Furthermore, inflammatory conditions induced chemically or due to autoimmunity reduced intestinal integrity, validating the use of the system.

CONCLUSIONS

The Ussing chamber has been used for many years to measure barrier function. However, a clear and informative methods paper describing the setup of modern equipment and step-by-step procedure to measure mouse and human intestinal permeability isn't available. The Ussing chamber system methodology we describe provides such detail to guide investigation of gut integrity.

A Deep Convolutional Neural Network Approach to Classify Normal and Abnormal Gastric Slow Wave Initiation From the High Resolution Electrogastrogram

OBJECTIVE

Gastric slow wave abnormalities have been associated with gastric motility disorders. Invasive studies in humans have described normal and abnormal propagation of the slow wave. This study aims to disambiguate the abnormally functioning wave from one of normalcy using multi-electrode abdominal waveforms of the electrogastrogram (EGG).

METHODS

Human stomach and abdominal models are extracted from computed tomography scans. Normal and abnormal slow waves are simulated along stomach surfaces. Current dipoles at the stomachs surface are propagated to virtual electrodes on the abdomen with a forward model. We establish a deep convolutional neural network (CNN) framework to classify normal and abnormal slow waves from the multi-electrode waveforms. We investigate the effects of non-idealized measurements on performance, including shifted electrode array positioning, smaller array sizes, high body mass index (BMI), and low signal-to-noise ratio (SNR). We compare the performance of our deep CNN to a linear discriminant classifier using wave propagation spatial features.

RESULTS

A deep CNN framework demonstrated robust classification, with accuracy above 90% for all SNR above 0 dB, horizontal shifts within 3 cm, vertical shifts within 6 cm, and abdominal tissue depth within 6 cm. The linear discriminant classifier was much more vulnerable to SNR, electrode placement, and BMI.

CONCLUSION

This is the first study to attempt and, moreover, succeed in using a deep CNN to disambiguate normal and abnormal gastric slow wave patterns from high-resolution EGG data.

SIGNIFICANCE

These findings suggest that multi-electrode cutaneous abdominal recordings have the potential to serve as widely deployable clinical screening tools for gastrointestinal foregut disorders.

Abnormal respiratory event detection in sleep: A prescreening system with smart wearables

Sleeping is an important activity to monitor since it has a crucial role in the overall health and well-being of the people and society. In order to diagnose the problems in sleep, different monitoring systems are developed in the literature. The unobtrusiveness, reduced cost, objectiveness, protection of privacy and user-friendliness are the main design considerations and the proposed system design achieves those objectives by utilizing smart wearables, smart watch and smart phone. The accelerometer and heart rate monitor sensors on smart watch and the sound level sensor on the smart phone are activated. The experiments with this system are performed with 17 subjects in a sleep clinic. The data collected from these subjects is used to generate various combinations by employing varied feature extraction, feature selection and sampling approaches. Five different machine learning algorithms are implemented and the classification results are generated using the various combinations of data, training and scoring strategies. The system performance is measured in two ways, the accuracy rate of distinguishing abnormal respiratory events is 85.95% and the classification success of subjects according to the problems in their respiration is one misclassification among 17 subjects. With all the methodology utilized in this study, the proposed system is a novel prescreening tool which recognizes the severity of problems in respiration during sleep.

Sonographic follow-up after endoscopic carpal tunnel release for severe carpal tunnel syndrome: a one-year neuroanatomical prospective observational study

BACKGROUND

Endoscopic carpal tunnel release (ECTR) has been gradually adopted for the treatment of severe carpal tunnel syndrome (CTS). However, perioperative assessment of neuroanatomical parameters of median nerve, which are important determinant of median nerve recovery, has rarely been reported. This one-year prospective study aimed to investigate the natural history of the neuroanatomical morphology of the median nerve after ECTR in severe CTS patients by high-frequency ultrasonography and assess the ability of neuroanatomical measures to quantify morphological recovery of the median nerve after ECTR.

METHODS

This study recruited 31 patients (44 wrists) with a definitive diagnosis of severe CTS and underwent ECTR operation. The edema length (EL) of median nerve from the inlet of the carpal tunnel to the proximal wrist was detected on long axis imaging plane and the anteroposterior diameter (D) and cross-sectional area (CSA) at the inlet of the carpal tunnel on short axis imaging plane were detected by high frequency ultrasound. All these metrics were detected at 3 days before surgery and at the 2nd week, 4th week, 3rd month, 6th month and 12th month after surgery separately.

RESULTS

There was no significant difference of each parameter between the 2-week postoperative (1.914 ± 0.598 cm in EL, 0.258 ± 0.039 cm in D and 0.138 ± 0.015 cm2 in CSA) and 3-days preoperative time points (P-EL =0.250; P-D = 0.125; P-CSA =0.712). From the fourth week to the third month after surgery, the parameters quickly improved. The EL (0.715 ± 0.209 cm), D (0.225 ± 0.017 cm) and CSA (0.117 ± 0.012 cm2) at the 3- month postoperative time points were more reduced than at the fourth week after surgery (P-EL < 0.001; P-D = 0.038; P-CSA =0.014). Thereafter, the neurological anatomy parameters recovered slowly. By the 12-month postoperative time points, the three parameters were neuroanatomically close to normal. Compared to the control group in D (0.213 ± 0.005 cm), there was no difference at the 12-month time point (0.214 ± 0.009 cm, P = 0.939). However, the difference in EL (0.098 ± 0.030 cm vs. 0.016 ± 0.011 cm) and CSA (0.103 ± 0.008 cm2 vs. 0.073 ± 0.005 cm2) between patients and healthy volunteers at the 12-month time point still existed (P-EL < 0.001; P-CSA < 0.001).

CONCLUSIONS

Neuroanatomical parameters were gradually improved after ECTR surgery. The best time for US follow up is at 3-month postoperative time point for patients who do not show clinical improvement, since at this time the change is the greatest for most CTS patients. This study has been registered in Chinese Clinical Trial Registry: ChiCTR-ROC-17014068 (retrospectively registered 20-12-2017).

Factors associated with limited hand motion after hand trauma

Hand injuries are common and have a significant impact on daily life. However, the factors associated with functional outcome after hand injuries are not well established. The purpose of this study was to identify factors that are independently associated with hand total active motion (TAM).A total of 50 patients with unilateral complex hand injury were included in this study. The associations between various demographic, injury-related, and clinical assessment factors and TAM were determined by univariate and multivariate linear regression analyses. Nerve injuries recognized during surgery and diagnosed with electrodiagnostic (EDX) studies were compared using Pearson chi-squared test.Among multiple injury-related and initial clinical assessment factors, nerve injury diagnosed with EDX studies, hospital stay length, elevated C-reactive protein, and skeletal injury were independently associated with TAM in the affected hand after adjusting for covariates. Nerve injuries diagnosed with EDX studies were not consistent with those recognized during surgery.Our results suggest that high-energy trauma leading to skeletal and nerve injury with inflammation is associated with limited hand motion after surgery and postoperative immobilization. A comprehensive EDX study may enable identifying occult or recovered nerve injuries, which would be helpful in understanding limitations in finger movements.

Instrumentation for electrodiagnostic studies

The instrument and accessories are an important part of the electrodiagnostic (EDX) testing. Their functional understanding is useful to recognize and reduce various artifacts and noise/interference in the signal. In this review, we will describe the technical specifications of various components of the instrument, and their effect on signals and noise. This will be illustrated using example of electromyography and nerve conduction studies. However the same principles also apply to other modalities of testing. We will also provide general strategies to reduce noise and artifacts, followed by some modality specific examples.

Superb Microvascular Imaging of the Median Nerve in Carpal Tunnel Syndrome: An Electrodiagnostic and Ultrasonographic Study

OBJECTIVE

To evaluate intraneural blood flow of the median nerve using superb microvascular imaging (SMI) and power Doppler ultrasonography (PDUS), and to examine their correlation with electroneuromyography in patients with carpal tunnel syndrome (CTS).

METHODS

A cross-sectional survey was used, and the study was conducted in the research unit of a training and research hospital. Patients diagnosed with CTS according to electroneuromyography studies were included in the study. Ultrasound measurements were taken using an Aplio-500 (Toshiba Medical System Corporation, Tokyo, Japan) device and a linear multifrequency 14-MHz probe. The cross-sectional area of the median nerve at the carpal tunnel level was measured by the direct tracing method using electronic calipers. The power Doppler ultrasonography and superb microvascular imaging scores were recorded by grading the vascularity between 0 and 3.

RESULTS

Evaluation was made of a total of 113 hands of 80 patients (18 men, 62 women) with a mean age of 34.67 ± 12.82 years. The mean duration of symptoms was 12.34 ± 6.66 months. When the patients were grouped as mild, moderate, and severe CTS, there was a statistically significant difference between the SMI and PDUS grades (P < .05). As the severity of CTS increased, an increase in SMI and PDUS scores was observed. There was a strong correlation between SMI scores and motor distal latency (r = .71/P = .026), amplitude of sensory action potential (r = -.77/P = .029), and sensory neurotransmission rate (r = .77/P = .029).

CONCLUSION

SMI seems to be more sensitive than PDUS for evaluating the vascularity of the median nerve in patients with CTS, and SMI grading is correlated with the ENMG results.

Fractionating magnesium ion from seawater for struvite recovery using electrodialysis with monovalent selective membranes

As the consumption of global phosphorus reserves accelerates, recovering phosphorus as struvite (MgNH₄PO₄·6H₂O) from wastewater is an important option for phosphorus recycling. However, magnesium source is one of the major limiting factors for struvite recovery. In this work, different from previous studies where seawater was used directly as magnesium source in struvite precipitation, an electrodialysis stack equipped with monovalent selective cation-exchange membranes was designed to fractionate Mg²⁺ from seawater for struvite recovery. Results revealed that Mg²⁺ fractionation was achieved effectively. The comparison on applying the driving force for ionic transport showed that constant voltage was more preferable than constant current due to its higher Mg²⁺ separation efficiency, current efficiency and lower energy consumption. Increasing voltage from 7 V to 13 V would improve Mg²⁺ permeation ratio from 72.9% to 80.5% into the product stream but simultaneously increased the energy consumption from 5.40 (kWh/kg MgCl₂) to 11.69 (kWh/kg MgCl₂). In addition, the investigation on the influence of Ca²⁺ co-existence and further struvite recovery experiments revealed that the variation of Ca²⁺ concentrations in seawater did not influence Mg²⁺ fractionation significantly, nevertheless it might reduce struvite recovery efficiency through forming calcium phosphate.

Charcot-Marie-Tooth Disease and Other Genetic Polyneuropathies

PURPOSE OF REVIEW

Genetic polyneuropathies are rare and clinically heterogeneous. This article provides an overview of the clinical features, neurologic and electrodiagnostic findings, and management strategies for Charcot-Marie-Tooth disease and other genetic polyneuropathies as well as an algorithm for genetic testing.

RECENT FINDINGS

In the past 10 years, many of the mutations causing genetic polyneuropathies have been identified. International collaborations have led to the development of consortiums that are undertaking careful genotype-phenotype correlations to facilitate the development of targeted therapies and validation of outcome measures for future clinical trials. Clinical trials are currently under way for some genetic polyneuropathies.

SUMMARY

Readers are provided a framework to recognize common presentations of various genetic polyneuropathies and a rationale for current diagnostic testing and management strategies in genetic polyneuropathies.

Axonal Sensorimotor Polyneuropathies

PURPOSE OF REVIEW

This article describes clinical features of axonal sensorimotor polyneuropathies based on selected etiologies.

RECENT FINDINGS

Axonal sensorimotor polyneuropathies have been well described for some time. Recent advances include the assessment of the incidence of peripheral neuropathy in the elderly, the recognition of the limited influence of electrodiagnostic testing on the clinical management of uncomplicated axonal sensorimotor polyneuropathy, the development of guidelines for treatment of painful neuropathy, the identification of risk factors predisposing patients for chemotherapy-induced neuropathy, a report on the association of metabolic syndrome and idiopathic axonal sensorimotor neuropathy, and the availability of more cost-effective genetic testing for identifying inherited polyneuropathies.

SUMMARY

Axonal sensorimotor polyneuropathies carry an extensive list of differential diagnoses. Diagnosis is based on detailed history, physical examination, recognition of associated neurologic and non-neurologic features, and appropriate testing. Disease-modifying treatments are lacking in many cases. Management focuses on modification of predisposing lifestyle and medical factors, rehabilitation, and pain relief.

The Clinical Diagnostic Utility of Electrophysiological Techniques in Assessment of Patients With Disorders of Consciousness Following Acquired Brain Injury: A Systematic Review

OBJECTIVE

To investigate the diagnostic utility of electrophysiological recordings during active cognitive tasks in detecting residual cognitive capacities in patients with disorders of consciousness (DoC) after severe acquired brain injury.

DESIGN

Systematic review of empirical research in MEDLINE, Embase, PsycINFO, and Cochrane from January 2002 to March 2016.

MAIN MEASURES

Data extracted included sample size, type of electrophysiological technique and task design, rate of cognitive responders, false negatives and positives, and excluded subjects from the study analysis. The Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) was used for quality appraisal of the retrieved literature.

RESULTS

Twenty-four studies examining electrophysiological signs of command-following in patients with DoC were identified. Sensitivity rates in healthy controls demonstrated variable accuracy across the studies, ranging from 71% to 100%. In patients with DoC, specificity and sensitivity rates varied in the included studies, ranging from 0% to 100%. Pronounced heterogeneity was found between studies regarding methodological approaches, task design, and procedures of analysis, rendering comparison between studies challenging.

CONCLUSION

We are still far from establishing precise recommendations for standardized electrophysiological diagnostic procedures in DoC, but electrophysiological methods may add supplemental diagnostic information of covert cognition in some patients with DoC.

The relationship between QDASH scale and clinical, electrophysiological findings in carpal tunnel syndrome

BACKGROUND

Carpal tunnel syndrome (CTS) occurs as a result of compression of the median nerve at the wrist. The Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) questionnaire is a selfadministered region-specific outcome instrument which measures symptom severity and functional status.

OBJECTIVES

The aim of this study was to evaluate the clinical and electrophysiological relationship with QDASH scale in CTS.

MATERIAL AND METHODS

The study included 99 females and 22 males in total out of 121 idiopathic CTS patients with the mean age of 47.9 ±9.5 years. Patients were divided clinically and electrophysiologically into 2 groups as severe and mild based on modified criteria defined by Italian CTS working group. Pain severity was evaluated by visual analog scale (VAS). Patients were evaluated functionally by QDASH scale and the relationship between clinical and electrophysiological effect intensity (degree) was examined.

RESULTS

QDASH scores were found significantly high in female patients, in patients with long disease duration (6 years and more), patients with clinically severe symptoms, and the ones with positive phalen test in both hands. Statistically significant positive relationship was found between QDASH scores, disease duration and clinical severity. However, no relationship was found between electrophysiological severity and QDASH. A mild and positive correlation was observed among disease duration, clinical severity and VAS. A small and positive correlation was detected between VAS and QDASH.

CONCLUSIONS

Although electrophysiological findings were prioritized in the follow-up and treatment strategies of CTS patients, clinical and patient-oriented assessment scales should be dealt together. Despite the electrophysiological findings, we believe that individual differences are effective in clinical and functional capacity. We conclude that since QDASH scale has a simple applicability in a short time, it can be used for assessing the symptom severity and disability of patients with CTS.

Neurophysiologic Studies in the Evaluation of Polyneuropathy

PURPOSE OF REVIEW

This article provides core information on the clinical neurophysiology techniques available for the investigation of disorders of the peripheral nervous system.

RECENT FINDINGS

The role of small fiber dysfunction in some types of polyneuropathy is being increasingly appreciated, and neurophysiologic techniques for evaluating the autonomic components of peripheral axons have enhanced our understanding of small fiber dysfunction.

SUMMARY

The principles of nerve conduction studies and needle EMG are presented in this article, along with the patterns of abnormality encountered in patients with polyneuropathy due to large and small fiber involvement.

Sensory Neuronopathies

PURPOSE OF REVIEW

The sensory neuronopathies are sensory-predominant polyneuropathies that result from damage to the dorsal root and trigeminal sensory ganglia. This review explores the various causes of acquired sensory neuronopathies, the approach to diagnosis, and treatment.

RECENT FINDINGS

Diagnostic criteria have recently been published and validated to allow differentiation of sensory neuronopathies from other polyneuropathies. On the basis of serial electrodiagnostic studies, the treatment window for the acquired sensory neuronopathies has been identified as approximately 8 months. If treatment is initiated within 2 months of symptom onset, there is a better opportunity for improvement of the patient's condition. Even though sensory neuronopathies are rare, significant progress has been made regarding characterization of their clinical, electrophysiologic, and imaging features. This does not hold true, however, for treatment. There have been no randomized controlled clinical trials to guide management of these diseases, and a standard treatment approach remains undetermined.