Peripheral neuropathy in patients with gout, beyond focal nerve compression: a cross-sectional study.

Neuropathies secondary to tophus compression in gout patients are well known; however, limited data exist on other types of peripheral neuropathies (PN). Our aim was to describe PN frequency, characteristics, distribution, patterns, and associated factors in gout patients through clinical evaluation, a PN questionnaire, and nerve conduction studies (NCS). This cross-sectional descriptive study included consecutive gout patients (ACR/EULAR 2015 criteria) from our clinic. All underwent evaluation by Rheumatology and Rehabilitation departments, with IRB approval. Based on NCS, patients were categorized as PN + (presence) or PN- (absence). PN + patients were further classified as local peripheral neuropathy (LPN) or generalized somatic peripheral neuropathy (GPN). We enrolled 162 patients, 98% male (72% tophaceous gout). Mean age (SD): 49.4 (12) years; mean BMI: 27.9 (6.0) kg/m2. Comorbidities included dyslipidemia (53%), hypertension (28%), and obesity (23.5%). Abnormal NCS: 65% (n = 106); 52% LPN, 48% GPN. PN + patients were older, had lower education, and severe tophaceous gout. GPN patients were older, had lower education, and higher DN4 scores compared to LPN or PN- groups (p = 0.05); other risk factors were not significant. Over half of gout patients experienced neuropathy, with 48% having multiplex mononeuropathy or polyneuropathy. This was associated with joint damage and functional impairment. Mechanisms and risk factors remain unclear. Early recognition and management are crucial for optimizing clinical outcomes and quality of life in these patients. Key Points Peripheral neuropathies in gout patients had been scarcely reported and studied. This paper report that: • PN in gout is more frequent and more diverse than previously reported. • Mononeuropathies are frequent, median but also ulnar, peroneal and tibial nerves could be injured. • Unexpected, generalized neuropathies (polyneuropathy and multiplex mononeuropathy) are frequent and associated to severe gout. • The direct role of hyperuricemia /or gout in peripheral nerves require further studies.

Electrodiagnostic subtyping in Guillain-Barré syndrome patients in the International Guillain-Barré Outcome Study.

BACKGROUND AND PURPOSE: Various electrodiagnostic criteria have been developed in Guillain-Barré syndrome (GBS). Their performance in a broad representation of GBS patients has not been evaluated. Motor conduction data from the International GBS Outcome Study (IGOS) cohort were used to compare two widely used criterion sets and relate these to diagnostic amyotrophic lateral sclerosis criteria. METHODS: From the first 1500 patients in IGOS, nerve conduction studies from 1137 (75.8%) were available for the current study. These patients were classified according to nerve conduction studies criteria proposed by Hadden and Rajabally. RESULTS: Of the 1137 studies, 68.3% (N = 777) were classified identically according to criteria by Hadden and Rajabally: 111 (9.8%) axonal, 366 (32.2%) demyelinating, 195 (17.2%) equivocal, 35 (3.1%) inexcitable and 70 (6.2%) normal. Thus, 360 studies (31.7%) were classified differently. The areas of differences were as follows: 155 studies (13.6%) classified as demyelinating by Hadden and axonal by Rajabally; 122 studies (10.7%) classified as demyelinating by Hadden and equivocal by Rajabally; and 75 studies (6.6%) classified as equivocal by Hadden and axonal by Rajabally. Due to more strictly defined cutoffs fewer patients fulfilled demyelinating criteria by Rajabally than by Hadden, making more patients eligible for axonal or equivocal classification by Rajabally. In 234 (68.6%) axonal studies by Rajabally the revised El Escorial (amyotrophic lateral sclerosis) criteria were fulfilled; in axonal cases by Hadden this was 1.8%. CONCLUSIONS AND DISCUSSION: This study shows that electrodiagnosis in GBS is dependent on the criterion set utilized, both of which are based on expert opinion. Reappraisal of electrodiagnostic subtyping in GBS is warranted.

Utilizing nerve conduction studies to identify very early Guillain-Barré syndrome and distinguish it from mimics in emergency settings.

INTRODUCTION/AIMS: Accurately diagnosing Guillain-Barré syndrome (GBS) in its early stages and distinguishing it from mimics poses challenges. This study aimed to evaluate the utility of an existing electrodiagnostic criterion in very early GBS (VEGBS) for discerning mimics. Additionally, we explored specific electrophysiological abnormalities in VEGBS to design a new diagnostic criterion for more accurate VEGBS diagnosis. METHODS: We retrospectively identified all patients with flaccid quadriparesis initially suspected of GBS who underwent nerve conduction studies (NCS) ≤4 days from symptom onset. We then retrieved their NCS data and applied an existing electrodiagnostic criterion for sensitivity and specificity analyses based on the final discharge diagnosis. Furthermore, we designed a new criterion based on the observed electrophysiological abnormalities that have maximum specificity and at least 50% sensitivity. RESULTS: Among 70 patients suspected of VEGBS, 44 (63%) received a final diagnosis of GBS, while in 26 (37%), the GBS diagnosis was later refuted. Umapathi's definite criterion exhibited a sensitivity of 61.36% and a specificity of 92.31%. The probable and possible groups showed very high sensitivity (90.91% and 100%, respectively); however, specificity was low (57.69% and 30.77%, respectively) in the very early stage. Our proposed criterion demonstrated a sensitivity of 88.64% (CI: 75.44%-96.21%) and a specificity of 96.15% (CI: 80.36%-99.90%). DISCUSSION: The criterion based on presumed electrophysiological correlates of specific early GBS pathophysiology proved more effective than the existing electrodiagnostic criterion in differentiating VEGBS from mimics.

Diminished levels of insulin-like growth factor-1 may be a risk factor for peripheral neuropathy in type 2 diabetes patients.

AIMS/INTRODUCTION: To investigate risk factors for diabetic peripheral neuropathy (DPN) and to explore the connection between insulin-like growth factor-1 (IGF-1) and DPN in individuals with type 2 diabetes. MATERIALS AND METHODS: A total of 790 patients with type 2 diabetes participated in a cross-sectional study, divided into two groups: those with DPN (DPN) and those without DPN (non-DPN). Blood samples were taken to measure IGF-1 levels and other biochemical markers. Participants underwent nerve conduction studies and quantitative sensory testing. RESULTS: Patients with DPN exhibited significantly lower levels of IGF-1 compared with non-DPN patients (P < 0.001). IGF-1 was positively correlated with the average amplitude of both motor (P < 0.05) and sensory nerves (P < 0.05), but negatively correlated with the vibration perception threshold (P < 0.05). No significant difference was observed between IGF-1 and nerve conduction velocity (P > 0.05), or the temperature detection threshold (P > 0.05). Multivariate regression analysis identified diabetes duration, HbA1c, and the low levels of IGF-1 as independent risk factors (P < 0.001). Receiver operating characteristic analysis determined that at 8 years duration of diabetes, 8.5% (69.4 mmol/mol) HbA1c and 120 ng/mL IGF-1, the optimal cut-off points, indicated DPN (P < 0.001). CONCLUSIONS: A reduction of IGF-1 in patients with DPN suggests a potential protective role against axon injury in large fiber nerves of type 2 diabetes patients.

Neurologic Complications of Leprosy: A Case Series.

Leprosy, caused by the Mycobacterium leprae complex, manifests as a chronic infection. Its hallmark presentation involves the neurocutaneous syndrome, characterized by peripheral nerve involvement and dermatologic lesions. Neurological complications significantly contribute to disability in leprosy patients. Peripheral neuropathy may manifest acutely or chronically, in either axonal or demyelinating forms, and can present as mononeuropathy, mononeuropathy multiplex, or polyneuropathy. The diverse clinical presentations emphasize the importance of considering leprosy in the differential diagnosis of peripheral neuropathy, enabling appropriate investigative approaches. Skin and nerve biopsies, slit skin smears, and nerve conduction studies serve as crucial diagnostic tools for identifying peripheral nerve involvement in leprosy. In this paper, we present three cases of leprosy with peripheral nerve involvement, discussing their clinical spectrum, diagnostic approach, and management.

Serial repetitive nerve stimulation studies in organophosphorus poisoning indicate two distinct pathophysiological processes occur at the neuromuscular junction in the intermediate syndrome.

INTRODUCTION: Intermediate syndrome is an important cause of respiratory failure following acute organophosphorus pesticide poisoning. The objective of this study was to examine the pathophysiology of this syndrome by analysis of sequential repetitive nerve stimulation studies in patients with acute organophosphorus pesticide poisoning. METHODS: Thirty-four consenting symptomatic patients with acute organophosphorus pesticide poisoning with intermediate syndrome (n = 10) or a milder forme fruste intermediate syndrome (n = 24) were assessed prospectively with daily physical examination and repetitive nerve stimulation done on the right and left median and ulnar nerves. The compound muscle action potential at 1, 3, 10, 15, 20 and 30 Hertz was measured with a train of ten stimuli. The amplitudes of the resulting stimuli were normalized to the first stimulus (100 per cent) and plotted against time. The decrease in the area under the curve of all the second stimulus compound muscle action potentials in the first 0.3 seconds was measured as a means of quantifying the refractory block. The decrease in the area under the curve under the 10, 15, 20 and 30 Hertz compound muscle action potentials relative to this pooled second stimulus compound muscle action potentials-area under the curve indicated the extent of additional rate-dependent block (decreasing compound muscle action potential-area under the curve over the first 0.3 seconds after the first stimulus with increasing Hertz). RESULTS: These new measurements strongly correlated with the severity of weakness. Refractory block was seen in most patients but was more severe in those with intermediate syndrome than those with forme fruste (partial) intermediate syndrome (median 55 per cent versus 16 per cent, P = 0.0001). Similar large differences were found for rate-dependent block (30 per cent versus 7 per cent, P = 0.001), which was uncommon in forme fruste intermediate syndrome but found in nine out of 10 patients with intermediate syndrome. Rate dependent block was generally only observed after 24 hours. The simplest strong predictor was total block at 30 Hertz repetitive nerve stimulation (89 per cent [interquartile range 73 to 94 per cent] versus 21 per cent [4 to 55 per cent]; P < 0.0001), which was very similar to total block calculated by summing other calculations. DISCUSSION: These findings likely represent depolarization and desensitization block from prolonged excessive cholinergic stimulation but it is not clear if these are from pre- or post-synaptic pathology. An animal model of intermediate syndrome with repetitive nerve stimulation studies might enable a better pathophysiological understanding of the two types of block. LIMITATIONS: The limited number of repetitive nerve stimulation studies performed were sufficient to demonstrate proof-of-concept, but further studies with more patients are needed to better define the correlates, clinical relevance and possible diagnostic/prognostic roles for the use of this technique. CONCLUSION: There are two easily distinguishable pathophysiological abnormalities in the neuromuscular block in intermediate syndrome. While they often coincide, both may be observed in isolation. The total and rate-dependent block at 30 Hertz are strongly associated with more severe weakness.

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.

Emotion Processing in Peripheral Neuropathic Pain: An Observational Study.

BACKGROUND: In clinical practice, the implementation of tailored treatment is crucial for assessing the patient's emotional processing profile. Here, we investigate all three levels of analysis characterizing emotion processing, i.e., recognition, representation, and regulation, in patients with peripheral neuropathic pain (PNP). METHODS: Sixty-two patients and forty-eight healthy controls underwent quantitative sensory testing, i.e., psychophysical tests to assess somatosensory functions such as perception of cold (CDT), heat-induced pain (HPT), and vibration (VDT), as well as three standardized tasks to assess emotional processing: (1) the Ekman 60-Faces Test (EK-60F) to assess recognition of basic facial emotions, (2) the Reading the Mind in the Eyes Test (RME) to assess the ability to represent the feelings of another person by observing their eyes, and (3) the 20-item Toronto Alexithymia Scale (TAS-20) to assess emotional dysregulation, i.e., alexithymia. RESULTS: General Linear Model analysis revealed a significant relationship between left index finger VDT z-scores in PNP patients with alexithymia. The RME correlated with VDT z-scores of the left little finger and overall score for the EK-60F. CONCLUSIONS: In patients with PNP, emotion processing is impaired, which emphasizes the importance of assessing these abilities appropriately in these patients. In this way, clinicians can tailor treatment to the needs of individual patients.

Predictors of Recovery in Facial Nerve Palsy: Insights From an Observational Study in Odisha, India.

Background Facial nerve paralysis, leading to the loss of facial expression, poses significant discomfort to patients. While most individuals exhibit a favorable response to treatment, a subset experiences enduring facial deformities without clearly defined etiology. This study aimed to identify prognostic factors influencing outcomes and quality of life in facial nerve palsy patients, contributing to enhanced clinical management. Methods A prospective observational study was conducted in the Otorhinolaryngology Department of Maharaja Krishna Chandra Gajapati Medical College and Hospital, a tertiary care hospital. We included patients presenting with any clinical variety of facial nerve palsy, irrespective of age and gender. Only moribund and noncompliant cases were excluded. Patients underwent clinical assessment using the House-Brackmann (HB) grading at presentation and were subsequently monitored at three weeks, three months, and six months post-onset to assess recovery. Results Out of 66 patients, 18 (27.27%) fully recovered at three weeks, 50 (75.76%) recovered at three months, and 54 (81.82%) at six-month follow-up. Incomplete recovery was observed in 13 (19.69%) patients. Factors associated with favorable outcomes included younger age of onset (p = 0.003), lower baseline HB grade (IV or less) (p = 0.001), Electroneurography Degeneration Index (ENoG DI) of <70% (p < 0.0001), early initiation of treatment (within five days of onset) (p = 0.0003), and absence of comorbid conditions (p = 0.03). Gender and affected side (left or right) did not influence the outcome. Conclusion In summary, age, associated comorbid conditions, baseline HB grade, and extent of facial nerve degeneration are crucial predictors of outcomes in facial nerve palsy. This knowledge can guide clinicians in optimizing treatment strategies for improved patient care.

Soleus Muscle H-reflex: Reference Data of Adult Population From a Tertiary Care Center in India.

Introduction The Hoffmann reflex (H reflex) is one of the most studied reflexes in human neurophysiological literature. Detection of the H reflex is useful in the diagnosis of early polyneuropathy, S1 radiculopathy, early GBS, tibial neuropathy and sciatica, and sacral plexopathy. The H reflex is also used as a tool to measure the excitability of the nervous components of the arc, regardless of the sensitivity of the sensory organs. The monosynaptic nature of reflex circuits makes H-reflex an attractive tool for clinical neurophysiology and research. Objective The objective is to create reference data of soleus H-reflex latency in an adult population from a tertiary care center in India. Materials and methods Seven hundred eighty-four healthy volunteers underwent a physical examination and brief electrophysiological examination before elicitation of the soleus H reflex of both lower extremities using standard techniques. Reference values ​​are expressed as mean ± standard deviation as well as the third and 97th percentiles for latency as the dependent variable. Results The study population included 346 (44.1%) women and 438 (55.9%) men. The men were aged 40.46 ± 14.76 years, and the women were aged 41.63 ± 13.49 years. The average weight of the men was 73.32 ± 10.28 kilograms, and the women were 62.91 ± 7.46 kilograms. The average height of the men was 172.06 ± 4.22 cm, and the women were 159.12 ± 2.42 cm. The third and 97th percentiles for H-reflex latency on the right side were 22.86 ms to 34.22 ms and on the left side were 22.86 ms to 35.39 ms. The average right tibial H latency and left tibial H latency were 28.18 ± 2.59 ms and 28.14 ± 2.70 ms, respectively. Conclusion A sizable subject population was used to provide reference data for this study. Because of the huge sample size and nearly appropriate coverage of different age groups, reference ranges have been established for various age, height, and BMI groups.

Harnessing historical data to derive reference limits - A comparison of e-norms to traditionally derived reference limits.

Objective: Nerve conduction studies (NCS) require valid reference limits for meaningful interpretation. We aimed to further develop the extrapolated norms (e-norms) method for obtaining NCS reference limits from historical laboratory datasets for children and adults, and to validate it against traditionally derived reference limits. Methods: We compared reference limits obtained by applying a further developed e-norms with reference limits from healthy controls for the age strata's 9-18, 20-44 and 45-60 years old. The control data consisted of 65 healthy children and 578 healthy adults, matched with 1294 and 5628 patients respectively. Five commonly investigated nerves were chosen: The tibial and peroneal motor nerves (amplitudes, conduction velocities, F-waves), and the sural, superficial peroneal and medial plantar sensory nerves (amplitudes, conduction velocities). The datasets were matched by hospital to ensure identical equipment and protocols. The e-norms method was adapted, and reference limit calculation using both ±2 SD (original method) and ±2.5 SD (to compensate for predicted underestimation of population SD by the e-norms method) was compared to control data using ±2 SD. Percentage agreement between e-norms and the traditional method was calculated. Results: On average, the e-norms method (mean ±2 SD) produced slightly stricter reference limits compared to the traditional method. Increasing the e-norms range to mean ±2.5 SD improved the results in children while slightly overcorrecting in the adult group. The average agreement between the two methods was 95 % (±2 SD) and 96 % (±2.5 SD). Conclusions: The e-norms method yielded slightly stricter reference limits overall than ones obtained through traditional methods; However, much of the difference can be attributed to a few outlying plots where the raters found it difficult to apply e-norms correctly. The two methods disagreed on classification of 4-5% of cases. Our e-norms software is suited to analyze large amounts of raw NCS data; it should further reduce bias and facilitate more accurate ratings. Significance: With small adaptations, the e-norms method adequately replicates traditionally derived reference limits, and is a viable method to produce reference limits from historical datasets.

Relationships between the global symptom score and electrophysiological findings after surgical release for carpal tunnel syndrome: Indications and outcomes.

PURPOSE: Regarding surgical indications for carpal tunnel syndrome (CTS), the hypothesis that the recovery processes of subjective symptoms differ among pain, sensory, and motor symptoms and correlate with recovery in objective nerve conduction studies was examined in the present study. METHODS: The global symptom score (GSS) is a method used to assess clinical outcomes and covers subjective symptoms, including pain (pain and nocturnal awakening), sensory (numbness and paresthesia), and motor (weakness/clumsiness) symptoms. The relationships between long-term changes in GSS and recovery in nerve conduction studies were investigated. RESULTS: Forty patients (40 hands) were included (mean age 65 years; 80% female; 68% with moderate CTS: sensory nerve conduction velocity < 45 m/s and motor nerve distal latency > 4.5 ms). Pain and nocturnal awakening rapidly subsided within 1 month after surgery and did not recur in the long term (median 5.6 years). Paresthesia significantly decreased 3 months after surgery and in the long term thereafter. Weakness/clumsiness significantly decreased at 1 year. Sensory nerve distal latency, conduction velocity, and amplitude significantly improved 3 months and 1 year after surgery, and correlated with nocturnal awakening in the short term (3 months) in moderate CTS cases. The patient satisfaction rate was 91%. CONCLUSION: Rapid recovery was observed in pain and nocturnal awakening, of which nocturnal awakening correlated with the recovery of sensory nerve conduction velocity. Patients with pain symptoms due to moderate CTS may benefit from surgical release.

Establishing the diagnosis of radial tunnel syndrome: a systematic review of published clinical series.

PURPOSE: Radial tunnel syndrome (RTS) is a controversial diagnosis due to non-specific exam findings and frequent absence of positive electromyography (EMG) and nerve conduction study (NCS) findings. The purpose of this study was to identify the methods used to diagnose RTS in the literature. METHODS: We queried PubMed, Embase, Web of Science, and Cochrane databases per PRISMA guidelines. Extracted data included article and patient characteristics, diagnostic assessments utilized and their respective findings, and treatments. Objective data were summarized descriptively. The relationship between reported diagnostic findings (i.e., physical exam and diagnostic tests) and treatments was assessed via a descriptive synthesis. RESULTS: Our review included 13 studies and 391 upper extremities. All studies utilized physical exam in diagnosing RTS; most commonly, patients had tenderness over the radial tunnel (381/391, 97%). Preoperative EMG/NCS was reported by 11/13 studies, with abnormal findings in 8.9% (29/327) of upper extremities. Steroid and/or lidocaine injection for presumed lateral epicondylitis was reported by 9/13 studies (46/295 upper extremities, 16%), with RTS being diagnosed after patients received little to no relief. It was also common to inject the radial tunnel to make the diagnosis (218/295, 74%). The most common reported intraoperative finding was narrowing of the PIN (38/137, 28%). The intraoperative compressive site most commonly reported was the arcade of Frohse (142/306, 46%). CONCLUSIONS: There is substantial heterogeneity in modalities used to diagnose RTS and the reported definition of RTS. This, in conjunction with many patients having concomitant lateral epicondylitis, makes it difficult to compare treatment outcomes for RTS. LEVEL OF EVIDENCE: Level III. Systematic review of retrospective and prospective cohort studies.

Utility of single fibre electromyography (SFEMG)and motor unit number estimation technique (MUNE) in the diagnosis and differentiation of polyneuropathies of different aetiology.

OBJECTIVE: To determine whether single fibre electromyography and motor unit number index can distinguish between axonal and myelin lesions in polyneuropathies. METHODS: This case-control study was conducted at the Department of Medical Physiology, School of Medicine, University of Duhok, Iraq, and the Neurophysiology Department, Hawler Teaching Hospital, Erbil, Iraq, from January 2021 to March 2022. Group A had patients diagnosed with polyneuropathy regardless of the aetiology, while group B had age-matched healthy controls. Both groups were subjected to single fibre electromyography and motor unit number index as well as conventional nerve conduction study and concentric needle electromyography. Data was analysed using SPSS 26. RESULTS: Of the 140 subjects, 60(43%) were patients in group A; 40(67%) males and 20(33%) females with mean age 55.3±7.2 years. There were 80(57%) controls in group B; 43(54%) females and 37(46%) males with mean age 53.81±7.15. Group A had significantly higher single fibre electromyography jitter, and mean consecutive difference (MCD) values than group B (p<0.05). Group A patients with axonal polyneuropathy had a higher mean jitter (MCD) value (36.476.7ms) than those with demyelinating polyneuropathy (23.262.31 ms) (P <0.05). Patients in group A had a motor unit number index value with a significantly lower mean value (p<0.05) when compared to the controls. Axonal polyneuropathy patients had a lower MUNIX value (99.612.8) than demyelinating polyneuropathy patients (149.845.7) (P< 0.05). CONCLUSIONS: Single fibre electromyography and motor unit number index could help differentiate between the pathophysiology of axonal and demyelinating polyneuropathy.

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.

The Diagnostic Utility of Ultrasound and Electrodiagnostic Studies in The Young and Old.

Purpose: Carpal tunnel syndrome is the most common compressive neuropathy. The diagnostic parameters currently used for the general adult population may not be valid in elderly or younger cohorts. The purpose of this study is to determine the diagnostic accuracy of nerve conduction studies (NCS) and ultrasound (US) in different age groups utilizing the 6-item Carpal tunnel syndrome (CTS) symptoms scale (CTS-6) as the reference standard. Methods: A retrospective database of patients who underwent US and NCS as part of the diagnostic work-up for suspected peripheral nerve compression was reviewed. Subjects were separated into three groups based on the median age of carpal tunnel syndrome patients (55 years of age) and two standard deviations (standard deviation 13.5 years) above and below the median. The young group was 28 years of age or less, the middle group was 29-71 years of age, and the old group was 72 years of age or greater. CTS-6 and Boston Carpal Tunnel Syndrome Questionnaire scores were recorded. Using CTS-6 as a reference standard, the sensitivity and specificity were calculated for NCS and US. Results: A total of 295 hands were included in the analysis with 23 hands in the young group and 24 hands in the old group. NCS showed 31% sensitivity and 100% specificity in the young group compared to 54% sensitivity and 90% specificity for US. NCS showed 94% sensitivity and 25% specificity in the old group compared to 81% sensitivity and 38% specificity for US. Overall accuracy for US and NCS was 66% for both tests when looking at all age groups. The accuracy in the young group was 70% for US and 61% for NCS, whereas the accuracy in the old group was 67% for US and 71% for NCS. Conclusions: US has comparable sensitivity and specificity to NCS in patients two or more standard deviations above or below the mean age for presentation of CTS. US may be more accurate in younger patients, although NCS limits the number of false positive tests. There remains a substantial amount of inaccuracy for both tests when using a validated clinical diagnostic tool (CTS-6) as the reference standard. Type of study/level of Evidence: Diagnostic IV.

Nerve Conduction Studies of the Larynx: Porcine Model and Human Application.

OBJECTIVE: There is a paucity of information in the literature about how electromyography (EMG) with nerve conduction studies (NCS) can be utilized in the field of neurolaryngology. The goal of this study was two-part: (1) to identify the NCS test parameters that best reflect underlying neurolaryngeal pathophysiology in a porcine model, and (2) to determine if comparable NCS parameters can be used to assess clinical laryngeal denervation injuries in patients. METHODS: Yukatan minipigs underwent general anesthesia with EMG and recurrent laryngeal NCS assessment. Recurrent laryngeal nerve (RLN) transection injury and uninjured RLN cases were included to determine NCS neuropathologic and normative findings, respectively. Our porcine analytic model was then applied to a clinical scenario of seven patients with RLN injury. RESULTS: The porcine model was able to differentiate and characterize normative and neuropathologic NCS changes. Clinical outcomes suggest that RLN NCS can be performed clinically and is overall well tolerated by in patients. Findings may serve as a useful tool to differentiate normal nerve function, neuropraxia, axonotmesis, and irreversible RLN injuries. CONCLUSION: This novel study is the first to demonstrate the feasibility and applicability of EMG with NCS in the evaluation of vocal fold function in a porcine model in addition to the clinical setting. Further studies are needed to better understand the clinical utility and predictive value in recovery of vocal fold paralysis.

Traumatic and iatrogenic sciatic nerve injury in 38 dogs and 10 cats: Clinical and electrodiagnostic findings.

BACKGROUND: Reports describing sciatic nerve injuries (SNI) and their outcome are scarce in veterinary medicine. HYPOTHESIS: Describe the causes of traumatic and iatrogenic SNI and evaluate which clinical and electrodiagnostic findings predict outcome. ANIMALS: Thirty-eight dogs and 10 cats with confirmed SNI referred for neurologic and electrodiagnostic evaluation. METHODS: Clinical and electrodiagnostic examination results, including electromyography (EMG), motor nerve conduction studies, muscle-evoked potential (MEP), F-waves, sensory nerve conduction studies, and cord dorsum potential (CDP), were retrospectively evaluated. Quality of life (QoL) was assessed based on owner interviews. RESULTS: Surgery (42%) and trauma (33%) were the most common causes of SNI; in dogs, 24% were caused by bites from wild boars. Ability to flex and extend the tarsus was significantly associated with positive outcome in dogs. Mean time from onset of clinical signs until electrodiagnostic evaluation was 67 ± 65 (range, 7-300) days and 65 ± 108 (range, 7-365) days for dogs and cats, respectively. A cut-off amplitude of 1.45 mV for compound motor action potentials (CMAP) was predictive of positive outcome in dogs (P = .01), with sensitivity of 58% and specificity of 100%. CONCLUSIONS AND CLINICAL IMPORTANCE: Clinical motor function predicts recovery better than sensory function. Electrodiagnostic findings also may play a role in predicting the outcome of SNI. Application of the proposed CMAP cut-off amplitude may assist clinicians in shortening the time to reassessment or for earlier suggestion of salvage procedures. Owners perceived a good quality of life (QoL), even in cases of hindlimb amputation.

Walter Eichler and his role in the development of electroneurography.

Walter Eichler (1904-1942) performed the first in situ nerve conduction studies in humans. Eichler's work has been largely overlooked and there have been no biographical accounts written of him. His 1937 paper, Über die Ableitung der Aktionspotentiale vom menschlichen Nerven in situ (On the recording of the action potentials from human nerves in situ) was translated and reviewed. Archival material was obtained on his career that was housed predominantly at the University of Freiburg im Breisgau. He had memberships in Nazi organizations but did not appear to be politically active. During his brief career, he constructed novel equipment and established seminal principles for performing nerve conductions on humans. The authors repeated his experiment in the ulnar nerve, which duplicated Eichler's findings. His recordings were quite remarkable given advances in technology. In summary, the Eichler paper is the first study in the development of in situ clinical electroneurography in humans. Many of his procedural observations are still fundamental in the current practice of electroneurography. As best can be determined, his study in humans did not appear ethically compromised. Although Eichler's personal background remains open to question, his paper is a seminal study in the history and development of clinical electroneurography.Abbreviations: AP: Action potential; C: Capacitor; CNP: Compound nerve potential; DC: Direct current; E1: Preferred term for active electrode; E2: Preferred term for reference electrode; NSDÄB: Nationalsozialistische Deutsche NSD-Ärtzebund (National Socialist German Doctors' League; NSDAP: Nationalsozialistische Deutsche Arbeiterpartei (National Socialist German Workers' Party/ Nazi Party); SS: Schutzstaffel (Protective Echelon or Squad of the Nazi party).

The weepy cry - short neural signal bursts in intraoperative neuromonitoring.

PURPOSE: This study aimed to establish an in-vitro alternative to existing in-vivo systems to analyze nerve dysfunction using continuous neuromonitoring (C-IONM). METHODS: Three hundred sixty-three recurrent laryngeal nerves (RLN) (N(pigs) = 304, N(cattle) = 59) from food industry cadavers were exposed by microsurgical dissection following euthanasia. After rinsing with Ringer's lactate, they were tempered at 22 °C. Signal evaluation using C-IONM was performed for 10 min at 2 min intervals, and traction forces of up to 2N were applied for a median time of 60 s. Based on their post-traumatic electrophysiological response, RLNs were classified into four groups: Group A: Amplitude ≥ 100%, Group B: loss of function (LOS) 0-25%, Group C: ≥ 25-50%, and Group D: > 50%. RESULTS: A viable in-vitro neuromonitoring system was established. The median post-traumatic amplitudes were 112%, 88%, 59%, and 9% in groups A, B, C, and D, respectively. A time-dependent further dynamic LOS was observed during the 10 min after cessation of strain. Surprisingly, following initial post-traumatic hyperconductivity, complete LOS occurred in up to 20% of the nerves in group A. The critical threshold for triggering LOS was 2N in all four groups, resulting in immediate paralysis of up to 51.4% of the nerves studied. CONCLUSION: Consistent with in-vivo studies, RLN exhibit significant intrinsic electrophysiological variability in response to tensile forces. Moreover, nerve damage progresses even after the complete cessation of strain. Up to 20% of nerves with transiently increased post-traumatic amplitudes above 100% developed complete LOS, which we termed the "weepy cry." This time-delayed response must be considered during the interpretation of C-IONM signals.