Chronic inflammatory demyelinating polyneuropathy after SARS-CoV2 vaccination: update of the literature and patient characterization

Since the beginning of worldwide vaccination against COVID-19 disease, some reports have revealed a possible relationship between SARS CoV2 vaccination and chronic inflammatory demyelinating polyneuropathy (CIDP). We reviewed the available evidences regarding this topic, adding three new cases to those reported so far, with the purpose to outline the characteristics of these post-vaccinal CIDP. Seventeen subjects were studied. A total of 70.6% of CIDP cases were related to viral vector vaccines, most occurring after the administration of the first dose. CIDPs that occurred after the second dose (17%) were temporally associated with mRNA vaccines. The clinical course and electrophysiology of all patients met the criteria for acute-subacute CIDP (A-CIDP). Administration of the viral vector vaccine was significantly correlated with a higher probability of having cranial nerve impairment (p = 0.004). The electrophysiological phenotype, laboratory and imaging data, and first-line therapies were substantially similar to those of the classical CIDP. The take-home message of the present paper is that the SARS CoV2 vaccine, especially the AstraZeneca vaccine, may be associated with inflammatory neuropathies with acute onset, often indistinguishable from Guillain-Barré syndrome (GBS). Hence, the importance of tracked prospectively patients with GBS occurred post-SARS-CoV2 vaccine. Distinguishing GBS from A-CIDP is crucial because treatment strategies and long-term prognosis are different.

Purtscher-like retinopathy in a patient with systemic tacrolimus vasculopathy

INTRODUCTION

Purtscher-like retinopathy is a rare occlusive retinal microangiopathy, whose pathogenesis has not been totally defined yet. Most frequent cause of Purtscher-like retinopathy is acute pancreatitis, but it may be triggered by other systemic or toxic conditions. We report herein a case of Purtscher-like retinopathy in the context of systemic tacrolimus vasculopathy.

CASE REPORT

A 56-years old male with history of kidney transplant was referred to local emergency room because of a global worsening of health conditions, with fatigue, muscular pain and diuresis contraction. During hospitalization the patient came to our attention for sudden and severe visual acuity impairment in both eyes. Extensive ophthalmological assessment, optical coherence tomography (OCT) and fluorescein angiography (FA) were performed disclosing a marked drop in best corrected visual acuity (BCVA) (20/200 in the right eye and 10/400 in the left eye) caused by a bilateral severe occlusive retinal microangiopathy complicated by diffuse retinal ischaemia and neovascular glaucoma. Muscular biopsy showed a necrotizing myopathy with autoimmune features, as indicated by conspicuous upregulation of MHC-I complex and microangiopathic changes, consistent with tacrolimus toxicity. Tacrolimus administration was interrupted, and intravenous glucocorticoids were administered. The large areas of retinal ischemia and neovascular glaucoma were treated with pan-retinal photocoagulation and intravitreal injections of bevacizumab with complete regression of iris neovascolarization. BCVA measured 20/200 in both eyes at last follow-up visit, 20 months after symptoms onset.

CONCLUSIONS

Purtscher-like retinopathy should be suspected in patients under treatment with calcineurin inhibitors especially in case of sudden and severe bilateral visual impairment.

Diagnosis and Management of Seronegative Myasthenia Gravis: Lights and Shadows

Myasthenia gravis (MG) is an antibody-mediated neuromuscular disease affecting the neuromuscular junction. In most cases, autoantibodies can be detected in the sera of MG patients, thus aiding in diagnosis and allowing for early screening. However, there is a small proportion of patients who have no detectable auto-antibodies, a condition termed "seronegative MG" (SnMG). Several factors contribute to this, including laboratory test inaccuracies, decreased antibody production, immunosuppressive therapy, immunodeficiencies, antigen depletion, and immune-senescence. The diagnosis of SnMG is more challenging and is based on clinical features and neurophysiological tests. The early identification of these patients is needed in order to ensure early treatment and prevent complications. This narrative review aims to examine the latest updates on SnMG, defining the clinical characteristics of affected patients, diagnostic methods, management, and therapeutic scenarios.

Anti-Cytosolic 5'-Nucleotidase 1A in the Diagnosis of Patients with Suspected Idiopathic Inflammatory Myopathies: An Italian Real-Life, Single-Centre Retrospective Study

BACKGROUND

Anti-cytosolic 5'-nucleotidase 1A (anti-cN1A) antibodies were proposed as a biomarker for the diagnosis of inclusion body myositis (IBM), but conflicting specificity and sensitivity evidence limits its use. Our study aimed to assess the diagnostic accuracy of anti-cN1A in a cohort of patients who underwent a myositis line immunoassay for suspected idiopathic inflammatory myopathies (IIM). We also assessed the agreement between two testing procedures: line immunoassay (LIA) and enzyme-linked immunoassay (ELISA).

MATERIALS AND METHODS

We collected retrospective clinical and serological data for 340 patients who underwent a myositis antibody assay using LIA (EUROLINE Autoimmune Inflammatory Myopathies 16 Ag et cN-1A (IgG) line immunoassay) and verification with an anti-cN1A antibody assay using ELISA (IgG) (Euroimmun Lubeck, Germany).

RESULTS

The serum samples of 20 (5.88%) patients (15 females, 5 males, mean age 58.76 ± 18.31) tested positive for anti-cN1A using LIA, but only two out of twenty were diagnosed with IBM. Seventeen out of twenty tested positive for anti-cN1A using ELISA (median IQR, 2.9 (1.9-4.18)).

CONCLUSIONS

Our study suggests excellent concordance between LIA and ELISA for detecting anti-cN1A antibodies. LIA may be a rapid and useful adjunct, and it could even replace ELISA for cN1A assay. However, the high prevalence of diseases other than IBM in our cohort of anti-cN1A-positive patients did not allow us to consider anti-cN1A antibodies as a specific biomarker for IBM.

Study of total duration of distal compound muscle action potential in demyelinating and axonal Guillain-Barre' syndrome

OBJECTIVES

Electrophysiology plays a crucial role in Guillain-Barré syndrome (GBS) diagnosis and subtype classification. The aim of our study was to assess the potential role of distal compound muscle action potential (dCMAP) for early differentiation between acute inflammatory demyelinating polyneuropathy (AIDP) and axonal GBS.

METHODS

We retrospectively reviewed the medical records of 24 subjects with AIDP and 18 subjects with axonal GBS. We built up receiver operating characteristic curves for total dCMAP duration and negative phase of dCMAP duration, in order to derive cut-off values able to differentiate between AIDP and axonal GBS.

RESULTS

The total duration of dCMAP was significantly prolonged in AIDP compared to axonal GBS. AUCs, odds ratio and positive predictive values were higher for total duration than for negative peak duration. Nerve conduction parameters in the lower limbs were more sensitive than those in the upper limbs in distinguishing AIDP from axonal GBS.

DISCUSSION

Total duration of dCMAP dispersion may capture an adjunctive component of distal demyelination, not measured by the more traditional parameters and may thus represent a useful tool for early differentiation between AIDP and axonal GBS.

Sex differences in neuromuscular disorders

The prevalence, onset, pathophysiology, and clinical course of many neuromuscular disorders (NMDs) may significantly differ between males and females. Some NMDs are more frequently observed in females, and characterized to show a higher grade of severity during or after the pregnancy. Meanwhile, others tend to have an earlier onset in males and exhibit a more variable progression. Prevalently, sex differences in NMDs have a familiar character given from genetic inheritance. However, they may also influence clinical presentation and disease severity of acquired NMD forms, and are represented by both hormonal and genetic factors. Consequently, to shed light on the distinctive role of biological factors in the different clinical phenotypes, we summarize in this review the sex related differences and their distinctive biological roles emerging from the current literature in both acquired and inherited NMDs.

Case report: A quantitative and qualitative diffusion tensor imaging (DTI) study in varicella zoster-related brachial plexopathy

Diffusion tensor imaging (DTI) is considered feasible for the nerve plexuses' imaging and quantitative evaluation but its value in the clinical practice is still virtually unexplored. We present the DTI profile of a case of acute varicella-zoster virus (VZV)-related brachial plexopathy. A 72-year-old woman presented with left upper-limb segmental paresis involving the spinal metamers C6-C7, preceded by a painful dermatomal vesicular eruption in C5-T1 dermatomes. Clinical and electrophysiological findings and magnetic resonance imaging indicated a plexus involvement. DTI analysis showed decreased fractional anisotropy (FA) and an increase of all the other diffusivity indexes, i.e., mean, axial, and radial diffusivity. The mechanisms underlying DTI parameter differences between healthy and pathologic brachial plexus sides could be related to microstructural fiber damage. Water diffusion is affected within the nerve roots by increasing the diffusion distance, leading to increased diffusion perpendicular to the largest eigenvalue and therefore to decreased FA values The role of DTI in clinical practice has not been defined yet. Additional quantitative and qualitative DTI information could improve the assessment and follow-up of brachial plexopathy.

A Novel Ultrasonographic Anthropometric-Independent Measurement of Median Nerve Swelling in Carpal Tunnel Syndrome: The "Nerve/Tendon Ratio" (NTR)

Background: There is little consensus on ultrasound (US) normative values of cross-sectional area of median nerve (MN-CSA) in carpal tunnel syndrome (CTS) because of its dependency on anthropometric parameters. We aim to propose a novel anthropometric-independent US parameter: MN-CSA/flexor radialis carpi CSA (FCR-CSA) ratio (“Nerve Tendon Ratio”, NTR), in the diagnosis of clinically and electrodiagnostic (EDS)-defined CTS. Methods: 74 wrists of 49 patients with clinically defined CTS underwent EDS (scored by the 1−5 Padua Scale of electrophysiological severity, PS) and US of carpal tunnel with measurement of MN-CSA (at the carpal tunnel inlet), FCR-CSA (over scaphoid tubercle) and its ratio (NTR, expressed as a percentage). US normality values and intra-operator agreement were assessed in 33 healthy volunteers. Results: In controls, the mean MN-CSA was 5.81 mm2, NTR 64.2%. In 74 clinical CTS, the mean MN-CSA was 12.1 mm2, NTR 117%. In severe CTS (PS > 3), the mean MN-CSA was 15.9 mm2, NTR 148%. In CTS, both MN-CSA and NTR correlated with sensitive conduction velocity (SCV) (p < 0.001), distal motor latency (DML) (p < 0.001) and PS (p < 0.001), with a slight superiority of NTR vs. MN-CSA when controlled for height, wrist circumference and weight. In CTS filtered for anthropometric extremes, only NTR maintained a correlation with SCV (p = 0.023), DML (p = 0.016) and PS (p = 0.009). Diagnostic cut-offs were obtained with a binomial regression analysis. In those patients with a clinical diagnosis of CTS, the cut-off of MN-CSA (AUROC: 0.983) was 8 mm2 (9 mm2 with highest positive predictive value, PPV), while for NTR (AUROC: 0.987), the cut-off was 83% (100% with highest PPV). In patients with EDS findings of severe CTS (PS > 3), the MN-CSA (AUROC: 0.876) cut-off was 12.3 mm2 (15.3 mm2 with highest PPV), while for NTR (AUROC: 0.858) it was 116.2% (146.0% with highest PPV). Conclusions: NTR can be simply and quickly calculated, and it can be used in anthropometric extremes.

Clinical Features and Outcome of the Guillain–Barre Syndrome: A Single-Center 11-Year Experience

Background

Clinical presentation, electrophysiological subtype, and outcome of the Guillain–Barre' Syndrome (GBS) may differ between patients from different geographical regions. This study aims to assess clinical–neurophysiological features of an adult, Italian GBS cohort over 11 years.

Methods

Retrospective (from 1 January 2011 to 31 December 2021) analysis was carried out on patients admitted to the Siena University Hospital who fulfilled the GBS diagnostic criteria. Demographic data, clinical characteristics, treatment, need of mechanical ventilation (MV), laboratory and electrophysiological tests, preceding infections/vaccination/other conditions, and comorbidities were collected for each patient.

Results

A total of 84 patients (51 men, median age of 61 years), were identified. GBS subtype was classified as acute inflammatory demyelinating polyneuropathy (AIDP) in the 66.6% of patients, acute motor/sensory axonal neuropathy (AMAN/AMSAN) in 20.2%, and the Miller Fisher syndrome in 5 (5.9%). Flu syndrome and gastrointestinal infection were the most common preceding conditions. In total, five (5.9%) subjects had concomitant cytomegalovirus (CMV) infection. Cranial nerve involvement occurred in 34.5% of subjects. Differences between the axonal and AIDP forms of GBS concerned the presence of anti-ganglioside antibodies. In total, seven (8.33%) patients required MV.

Discussion

The epidemiological and clinical characteristics of GBS in different countries are constantly evolving, especially in relation to environmental changes. This study provides updated clinical-epidemiological information in an Italian cohort.

Electrophysiological Study of the Tibial Nerve Across the Tarsal Tunnel in Distal Symmetric Diabetic Polyneuropathy

OBJECTIVE

The aim of the study was to demonstrate abnormalities of motor conduction of the tibial nerve across the tarsal tunnel in type 2 diabetes.

DESIGN

One hundred twenty-four consecutive patients (mean age = 66.6 yrs, 62.1% male) with distal symmetric diabetic polyneuropathy clinically diagnosed were prospectively enrolled. Nerve conduction studies of deep peroneal, tibial, superficial peroneal, medial plantar, and sural nerves and standard needle electromyography in the lower limbs were performed. Demographic, anthropometric, and clinical findings were collected.

RESULTS

Motor conduction velocity of the tibial nerve across tarsal tunnel was slowed in 60.5% of patients; another 4% showed conduction block across tarsal tunnel without reduction of motor conduction velocity. Overall percentage of abnormalities across tarsal tunnel (64.5%) exceeds that of the sensory conduction velocities of proximal sural and superficial peroneal nerves. Abnormal tibial motor conduction velocity across tarsal tunnel represents the most common abnormality among all motor nerve conduction study parameters and significantly correlates with hemoglobin level, diabetic neuropathic index score, and diabetic complications frequency.

CONCLUSIONS

Tibial conduction abnormalities across tarsal tunnel are the most sensitive motor parameter in distal symmetric diabetic polyneuropathy, second only to conduction abnormalities of sensory/mixed distal nerves of the feet. The use of nerve conduction studies across tarsal tunnel of the tibial nerve may be useful in the electrophysiological protocol to confirm the diagnosis of distal symmetric diabetic polyneuropathy.

Somatosensory evoked potentials and transcranial color Doppler monitoring in subarachnoid hemorrhage

OBJECTIVES

The outcome of patients with subarachnoid hemorrhage (SAH) is broadly influenced by the complications that may result from the hemorrhage. We describe a series of subjects, in which neurophysiological monitoring executed by simultaneous recording of somatosensory evoked potentials (SEPs) and transcranial color Doppler (TCD) was performed to reveal possible, early complications following acute SAH.

MATERIALS AND METHODS

We described the absolute and interhemispheric values of SEPs from the upper limb and TCD examinations of the cerebral arteries in 13 subjects with acute SAH.

RESULTS

In cases with middle cerebral artery (MCA) vasospasm, N20 SEP amplitude absolute values for the hemisphere involved in the vasospasm were much lower than the contralateral ones. The N20 amplitude ratio reduction correlated with reciprocal of MCA mean flow velocity values detected within each patient. In the subjects with early ischemic damage following SAH, the affected hemisphere showed N20 amplitude drop; in addition, the relationship between SEPs and TCD findings was missing.

CONCLUSION

Our findings emphasize the utility of simultaneous evaluation of SEPs and TCD in SAH follow-up, since the two methods reflect different pathomechanisms of possible secondary brain damage in aneurysmal SAH.

A new mutation in DNM2 gene in a large Italian family

The Charcot-Marie-Tooth (CMT) disease is the most common inherited peripheral neuropathy with great clinical and genetic heterogeneity. Mutations in DNM2 have been associated with CMT dominant intermediate B (CMTDIB). However, mutations in the same gene are known to induce also axonal CMT (CMT2M) or centronuclear myopathy. Moreover, the ability of effectively and simultaneously sequencing different CMT-related genes by next-generation sequencing approach makes it possible to detect even the presence of modifier genes that sometimes give reason of clinical variability in the context of complex phenotypes. Here, we describe an Italian family with very variable severity of phenotype among members harboring a novel DNM2 gene mutation which caused a prevalent CMT2M phenotype. The contemporary presence of a de novo variant in PRX gene in the most severely affected family member suggests a possible modulator effect of the PRX variant thus highlighting the possible impact of modifier genes in CMT.

Impact of β-range-induced oscillatory activity on human input-output relationship of the corticospinal pathway

Objective: The aim of the study was to show that short-lasting (90 s) transcranial alternating current stimulation (tACS) at 20 Hz delivered over the left primary motor cortex (M1) is able to change the shape of recruitment curve of the corticospinal pathway.Methods: The corticospinal pathway was studied during tACS by means of the relationship between the intensity of transcranial magnetic stimulation (TMS) delivered over the left M1 and corresponding motor evoked potentials (MEPs) recorded from the right first dorsal interosseus muscle (FDI), in nine healthy subjects. In order to extract characteristics of the input-output relationship that have particular physiological relevance, data were fitted to the Boltzmann sigmoidal function by the Levenberg-Marquardt nonlinear, least mean squares algorithm.Results: The β-rhythm tACS influenced the shape and parameters of the input-output relation, so that the initial segment of the conditioned curve (from threshold to 30% of maximum muscle size) diverged, while the subsequent segment converged to overlap the unconditioned control curve.Discussion: β-rhythm tACS conditions only a definite subset of corticospinal elements influencing less than 30% of the entire motoneuronal pool. The fact that β-rhythm tACS mainly affects the most excitable motoneurons could explain the observed antikinetic effect of the tACS at β-rhythm applied in the motor regions.

The effects of anthropometric and demographic factors on conduction parameters of the ulnar nerve: Multivariate analysis

The objective of the study is to investigate the effects of age, height, gender, body mass index (BMI), waist-to-hip ratio (WHR), arm and elbow measures on ulnar nerve conduction. We enrolled 261 "disease-free" subjects. We analyzed motor conduction velocity (MCV) in across elbow (AE) and forearm tracts, and sensory conduction velocity in 4th, 5th digit-wrist tracts (U4, U5) and in dorsal ulnar cutaneous nerve (DUC). We calculated the amplitudes of sensory and motor potentials (CMAPa and SNAPa), % of CMAPa drop AE, MCV drop and distal motor latency (DML). Univariate and multivariate analyses were performed. We estimated the predictive equations. The median nerve was examined for comparison. Age was negatively correlated with all conduction parameters. Forearm and AE MCV, % of CMAPa drop, DML, U4 and U5 SCV also depended upon height. Females had higher U4 and U5 SNAPa than males. BMI showed inverse relationship with U4 and U5 SNAPa. DUC parameters depended upon BMI and arm length. Similar trends were observed for the median nerve. "Normative" ulnar conduction parameters should be adjusted for demographic and anthropometric measures to improve diagnostic sensitivity.

Reference values for distal motor conduction of the tibial nerve: Effects of demographic and anthropometric measures

INTRODUCTION

In this study we collected reference values for the across-tarsal-tunnel conduction of the motor tibial nerve (mTN).

METHODS

The mTN compound muscle action potentials (CMAPs) from the abductor hallucis muscle were obtained by stimulating below/above the malleolus and the popliteal fossa. The effect of weight, height, body mass index (BMI), foot and leg length, sex, and age were evaluated using univariate and multivariate correlation analyses, and predictive equations for each mTN conduction parameter were developed.

RESULTS

On the basis of data from 185 subjects, there were differences between women and men in all anthropometric parameters and for some nerve conduction values. Through multivariate analysis, age, but not sex, was found to have a significant impact. Height affected both distal and proximal conduction velocity. BMI affected CMAP amplitude.

DISCUSSION

mTN conduction is influenced by various demographic and anthropometric factors. For all intrinsic factors, height demonstrated the greatest effect on mTN conduction across the tarsal tunnel.

Effects of elastic stockings on peripheral and central nervous system

BACKGROUND

Prospective study to investigate the effects of elastic stockings (GCS) 23-32 mmHg at ankle on Hoffmann reflex (H-reflex) from soleus muscle under rest and after a walking program.

METHODS

Fourteen subjects wore two types of GCS, at different times. Electrophysiological examinations were carried out at rest without and with GCS, immediately after walking with GCS and 20 minutes later after removing GCS.

RESULTS

Peripheral nerve conduction remained unchanged after using the GCS. Conversely, walking with GCS led to changes in a spinal cord pathway expressed as a decrease of H-threshold and an increase of H-size as a function of stimulus intensity, which lasted for at least 20 minutes.

CONCLUSIONS

GCS has no effect on the peripheral nervous system. The GCS intolerance and the discomfort sometimes reported by patients do not derive from a dysfunction of the lower limb peripheral nervous system. A positive action on spinal reflex excitability is detected after walking while wearing GCS. We suggest that nervous descending activity due to voluntary contractions, and afferent cutaneous discharge, enhanced by movement under compression, converge on inhibitory interneurons, thus impinging on presynaptic pathways. All this can lead to an enhancement of the monosynaptic responses. Higher limb oxygenation detected during walking with GCS, found by other Authors, could increase the sensitivity of the muscle spindle afferents and/or motor neuron excitability resulting in an increase in H-reflex excitability, with potential positive effects on neuromuscular activities improving proprioception and postural control of the lower limbs.

Functional and Brain Activation Changes Following Specialized Upper-Limb Exercise in Parkinson's Disease

For the management of Parkinson's disease (PD), the concept of forced exercise (FE) has drawn interest. In PD subjects, the FE executed with lower limbs has been shown to lessen symptoms and to promote brain adaptive changes. Our study is aimed to investigate the effect of an upper-limb exercise, conceptually comparable with the FE, in PD. Upper-limb exercise was achieved in a sitting position by using a specially designed device (Angel's Wings^®). Clinical data, computerized dynamic posturography, magnetic resonance imaging (MRI) (resting-state MRI and arterial spin labeling), and neuropsychological tests were used before and after 2 months' exercise training. We found a significant long-lasting improvement in Unified Parkinson Disease Rating Scale (UPDRS)-III and cognitive scales, along with improvement in balance and postural control (better alignment of the gravity center and improvement in weight symmetry and in anticipatory motor strategies). Computerized dynamic posturography pointed out an enhanced central ability to integrate the vestibular signals with afferents from other sensory systems. Neuroimaging analyses after 2 months' exercise training showed, with respect to pretraining condition, many changes. An increase of the cerebral blood flow was evident in the left primary motor cortex (M1), left supplementary motor cortical area, and left cerebellar cortex. The bilateral globus pallidus showed an increased functional connectivity to the right central operculum, right posterior cingulate gyrus, and left sensorimotor cortex. Seed-to-voxel analysis demonstrated a functional connectivity between M1 and the left superior frontal gyrus. Left crus II showed strengthened connections with the left pre-rolandic area, left post-rolandic area, and left supramarginal area. These findings likely reflect compensatory mechanisms to the neuropathological hallmark of PD. Overall, our results show that this upper-limb exercise model, conceptually comparable with the FE already tested in the lower limbs, leads to a global improvement (involving non-exercised limbs) likely consistent with the functional changes observed in the central nervous system.

Spasmophilia and entrapment nerve syndrome comorbidities in fibromyalgic patients: a possible neuromuscular pain generator

This paper is aimed at investigating whether peripheral dysfunction at the neuromuscular level may represent a pain generator in fibromyalgia. We studied the prevalence of spasmophilia (SP), carpal tunnel syndrome (CTS) and ulnar neuropathy at the elbow (UNE) in a group of 40 subjects suffering from fibromyalgia. Clinical and electrophysiological data were obtained to ascertain whether comorbid conditions were present. For subjective evaluation of symptoms severity, validated questionnaires for CTS and UNE were completed by patients. Twenty subjects were positive for SP (50%); CTS was diagnosed in 12 subjects (30%); no patient suffered from UNE; 6 subjects were affected at the same time by SP and CTS (15%); 14 subjects (35%) were affected by SP alone. The prevalence of CTS and SP was higher in fibromyalgia subjects than in the general population. The scores of the questionnaires related to CTS were significantly higher in fibromyalgia subjects positive for CTS, with respect to the other subjects. In fibromyalgia, CTS and SP may be considered clinical entities in themselves, the importance of which lies in their acting as peripheral pain generators that enhance or initiate central sensitization, thereby contributing to chronic widespread pain. The amplification of pain is indeed a correctable/misguided message that occurs inside the brain of fibromyalgia subjects and identification and local treatment of pain generators would lessen the total pain burden. The magnitude of the overlap in symptoms between fibromyalgia and CTS/SP necessitates careful investigation of these conditions.

Diagnostic Accuracy of Sensory Clinical Findings of the Hand Dorsum and of Neurography of the Dorsal Ulnar Cutaneous Nerve in Ulnar Neuropathy at the Elbow

OBJECTIVE

The main objective is to investigate the diagnostic accuracy and the relation of touch sensation and subjective sensory symptoms in the medial aspect of the hand dorsum, and neurography of the dorsal ulnar cutaneous nerve (DUCN) in ulnar neuropathy at the elbow (UNE). Secondary objective is to report the electrophysiological occurrence of anatomical variant of sensory innervation of the medial aspect of the hand dorsum from superficial radial nerve (SRN).

DESIGN

Prospective, cohort study.

SETTING

Electromyography laboratory.

PARTICIPANTS

Consecutive participants (N=282), those with UNE (n=81) and those without UNE (n=201), were enrolled.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Accuracy and agreement between sensory clinical findings of the medial hand dorsum and neurography of DUCN in UNE diagnosis.

RESULTS

DUCN neurographic and sensory findings had high specificity and relatively low sensitivity. Normal or abnormal sensory nerve action potential (SNAP) of DUCN matched with normal or abnormal touch sensation of the medial aspect of hand dorsum. Abnormal DUCN SNAP was related to the clinical severity of UNE and to the axonal damage of the ulnar nerve. Anatomical variant of the innervation of hand dorsum from SRN was demonstrated in 31 of 564 hands (6.2%) belonging to 26 of 282 participants (9.2%). If the variant was present, DUCN SNAP of the same side was more frequently absent or of low amplitude.

CONCLUSIONS

The utility of DUCN neurography and sensory findings of the medial aspect of the dorsum of the hand is limited in the diagnosis of UNE. However, if DUCN SNAP is absent or low in amplitude, it is advisable to check the presence of the anatomical variant of the innervation of the medial aspect of the hand dorsum from SRN.

Reappraisal of the F/M amplitude ratio in carpal tunnel syndrome

The F-wave/M-wave amplitude (F/M-amp) ratio has been shown to be increased in peripheral neuropathies, provided the maximum M-wave is relatively preserved. Reduced M-wave amplitudes and central facilitation of antidromically-induced reactivation of the anterior horn cells' axon hillocks (F-wave) are believed to contribute to higher F/M-amp ratios. The present study was undertaken to re-evaluate mechanisms responsible for higher F/M-amp ratios in carpal tunnel syndrome (CTS). We enrolled 232 cases affected by CTS and 108 controls. Fand M-wave amplitudes and F-wave chronodispersion were analyzed for the median and ulnar nerves. The F/M-amp ratio of the median nerve in CTS subjects with moderate-severe nerve damage was significantly higher than that of mild CTS subjects and controls. Chronodispersion of the median nerve F-wave increased with increasing CTS severity. We conclude that the relative preservation of the median nerve F-wave is due to damage to the large diameter muscle afferent fibers responsible for the monosynaptic response. Absence of the monosynaptic response makes the small motoneurons, usually inaccessible to the antidromic volley because of its collision with the orthodromic reflex volley, able to fire in the F-wave.

Neuromuscular excitability changes produced by sustained voluntary contraction and response to mexiletine in myotonia congenita

OBJECTIVE

To investigate the cause of transient weakness in myotonia congenita (MC) and the mechanism of action of mexiletine in reducing weakness.

METHODS

The changes in neuromuscular excitability produced by 1min of maximal voluntary contractions (MVC) were measured on the amplitude of compound muscle action potentials (CMAP) in two patients with either recessive or dominant MC, compared to control values obtained in 20 healthy subjects. Measurements were performed again in MC patients after mexiletine therapy.

RESULTS

Transient reduction in maximal CMAP amplitude lasting several minutes after MVC was evident in MC patients, whereas no change was observed in controls. Mexiletine efficiently reduced this transient CMAP depression in both patients.

DISCUSSION

Transient CMAP depression following sustained MVC may represent the electrophysiological correlate of the weakness clinically experienced by the patients. In MC, the low chloride conductance could induce self-sustaining action potentials after MVC, determining progressive membrane depolarization and a loss of excitability of muscle fibers, thus resulting in transient paresis. Mexiletine may prevent conduction block due to excessive membrane depolarization, thus reducing the transient CMAP depression following sustained MVC.

Severity of Carpal Tunnel Syndrome and Diagnostic Accuracy of Hand and Body Anthropometric Measures

Objective

To study the diagnostic properties of hand/wrist and body measures according to validated clinical and electrophysiological carpal tunnel syndrome (CTS) severity scales.

Methods

We performed a prospective case-control study. For each case, two controls were enrolled. Two five-stage clinical and electrophysiological scales were used to evaluate CTS severity. Anthropometric measurements were collected and obesity indicators and hand/wrist ratios were calculated. Area under the receiver operating characteristic curves (AUC), sensitivity, specificity, and likelihood ratios were calculated separately by gender.

Results

We consecutively enrolled 370 cases and 747 controls. The wrist-palm ratio, waist-hip-height ratio and waist-stature ratio showed the highest proportion of cases with abnormal values in the severe stages of CTS for clinical and electrophysiological severity scales in both genders. Accuracy tended to increase with CTS severity for females and males. In severe stage, most of the indexes presented moderate accuracy in both genders. Among subjects with severe CTS, the wrist-palm ratio presented the highest AUC for hand measures in the clinical and electrophysiological severity scales both in females (AUC 0.83 and 0.76, respectively) and males (AUC 0.91 and 0.82, respectively). Among subjects with severe CTS, the waist-stature ratio showed the highest AUC for body measures in the clinical and electrophysiological severity scales both in females (AUC 0.78 and 0.77, respectively) and males (AUC 0.84 and 0.76, respectively). The results of waist-hip-height ratio AUC were similar.

Conclusions

Wrist-palm ratio, waist-hip-height ratio and waist-stature ratio could contribute to support the diagnostic hypothesis of severe CTS that however has to be confirmed by nerve conduction study.

Listeria meningoencephalitis and anti-GQ1b antibody syndrome

We report the first case of Listeria monocytogenes meningoencephalitis associated with anti-GQ1b antibody syndrome in an immunocompetent adult. A prompt diagnosis, made thanks to the multidisciplinary contribution, allowed a combined therapeutic approach leading to final favourable outcome, despite several intercurrent complications.

Pathophysiology of knee jerk reflex abnormalities in L5 root injury

Although the knee jerk reflex is mediated by the L3 and L4 nerve roots, evidence exists that altered knee jerk expression may occur with exclusively L5 radiculopathy. The present study set out to identify the factors responsible for knee jerk reflex abnormalities in L5 monoradiculopathy. We analyzed clinical and electrophysiological data in 56 subjects affected by L5 monoradiculopathy. Seventeen patients (30.3%) showed an abnormal knee reflex. L5 patients with an abnormal knee reflex differed significantly, in severity of pretibial muscle damage, from those with a normal knee reflex. On the basis of evidence, in humans, of a specific spinal pathway linking the pretibial and quadriceps muscles, we infer that an impairment of the proprioceptive drive from the pretibial muscles to spinal premotor excitatory interneurons contacting quadriceps motor neurons is the main causative factor responsible for reducing knee jerk expression. This mechanism should be considered to avoid misinterpretation of knee jerk reflex changes in lumbar radiculopathies.

Anthropometric measurements as a screening test for carpal tunnel syndrome: receiver operating characteristic curves and accuracy

OBJECTIVE

To identify optimal cutoff values for body, hand, and wrist measurements in order to correctly identify individuals with carpal tunnel syndrome (CTS), using receiver operating characteristic (ROC) curves.

METHODS

We enrolled patients with CTS and control subjects at a 1:2 ratio, regardless of age and sex. The diagnosis of CTS was based on clinical findings and delayed distal conduction velocity of the median nerve. The anthropometric measurements included weight, height, waist circumference, hip circumferences, wrist depth/width, third digit length, and palm length/width. Obesity indicators and hand/wrist ratios were calculated. Area under the ROC curve (AUC), sensitivity, specificity, and likelihood ratios were calculated separately according to sex. To assess the role of multiple anthropometric measurements, we fit multivariable logistic regression models including age, wrist ratio, shape index, body mass index, and waist-to-hip ratio.

RESULTS

The study group comprised 1,117 subjects (250 female patients and 474 female controls; 120 male patients and 273 male controls). In women, the accuracy of all anthropometric measures was low (AUC ≤0.64). In men, the accuracy of the hand ratio, shape index, and wrist-to-palm ratio was moderate (AUC = 0.75). The estimates from the multivariable models confirmed the well-known associations between the selected variables and the risk of CTS, but the use of multiple predictors did not dramatically improve the diagnostic performance observed for single anthropometric indexes.

CONCLUSION

In clinical practice, the cutoff values for many anthropometric measurements have limited value as tools for the diagnosis of CTS.

Sensory axons excitability changes in carpal tunnel syndrome after neural mobilization

Increased mechanosensitivity of the median nerve in carpal tunnel syndrome (CTS) has been demonstrated during upper limb tension test 1 (ULTT1) when the nerve is passively elongated. However, the neurophysiological changes of the sensory axons during stressing activities are unknown. The aim of present study was to verify possible changes in the excitability of median nerve afferent axons following nerve stress in elongation, in subjects with and without CTS. Eight CTS hands and eight controls were selected. Recruitment properties of the median nerve were studied by analyzing the relationship between the intensity of electrical stimulation and the size of motor response, before and after intermittent-repetitive neural mobilization. Only in CTS hands, after the intervention, the stimulus-response curve was strikingly abnormal: both plateau and slope values were significantly lower. During anatomical stress across the median nerve in elongation, compressive forces may exert mechanical traction on the median nerve, since it is 'tethered' at the carpal tunnel, resulting inactivation of Na(+) channels at the wrist, or impairment of energy-dependent processes which affect axonal conduction block. We conclude that in entrapment neuropathies, neural mobilization during nerve elongation may generate conduction failure in peripheral nerve. Our study supports specific considerations for patient education and therapeutic approaches.

Waist circumference and waist-to-hip ratio in carpal tunnel syndrome: a case-control study

BACKGROUND

The association between carpal tunnel syndrome (CTS) and high body mass index (BMI) and some hand measures is well known. No study has been specifically focused on waist circumference (WC) and waist-to-hip-ratio (WHR). The aim of this prospective case-control study is to evaluate the association between CTS and WC, WHR and other body and hand anthropometric measures.

METHODS

We consecutively enrolled one "idiopathic" CTS case for two controls in 3 outpatient electromyography labs. The main anthropometric measures were BMI, WC, WHR, wrist ratio (WR) and hand ratio (HR). We performed univariate and multivariate analyses.

RESULTS

Female cases and controls were 250 and 474 and male cases and controls were 120 and 273, respectively. At univariate analysis there were differences in many anthropometric measures between cases and controls. At multivariate logistic regression analyses high BMI, WC and WHR and abnormal HR and WR were independent risk factors for CTS. Crossing two categories between BMI, WC and WHR, the overweight subjects, especially females, were at risk only if they had very high WC or high WHR. The risk increased if they were obese.

CONCLUSIONS

High WC/WHR doubles the risk of CTS, the risk further increased if overweight/obese subjects have also very high WC or high WHR. The obese subjects were always at risk regardless of WC and WHR values. Metabolic causes of this association with CTS were hypothesised. BMI is not the only and most powerful body predictor of "idiopathic" CTS, but also WHR and WC should be considered. These measures may not be interchangeable and it may be desirable to consider the utility of their joint use.

Rhabdomyolysis in an elderly multitreated patient: multiple drug interactions after statin withdrawal

Rhabdomyolysis precipitated by multitherapy is most frequently described during statin treatment, due to impairment of statin clearance by drugs sharing cytochrome P450 biotransformation pathway. Modulation of membrane transporters for drug efflux, operated by substrates, can also affect drugs' tissue levels. We report rhabdomyolysis in an elderly patient, in multitreatment with different potentially myotoxic medications, taking place seven months after atorvastatin discontinuation. Affected by ischaemic heart disease, arterial hypertension and dementia-related behaviour disturbances, the patient was receiving angiotensin 2-receptor inhibitors, beta-blockers, vasodilators, diuretics, salycilates, allopurinol, proton pump inhibitors, antipsychotics and antidepressants. He had taken atorvastatin for 14 years, with constantly normal creatine-kinase plasma levels. Two months after addition of the antianginal drug ranolazine, creatine-kinase mildly increased and atorvastatin was withdrawn. Nonetheless, creatine-kinase progressively rose, with severe weakness and rhabdomyolysis developing seven months later. Muscle biopsy showed a necrotizing myopathy with no inflammation or autoimmune changes. After ranolazine withdrawal, creatine-kinase and myoglobin returned to normal levels and strength was restored. Several psychotropic and cardiovascular medications prescribed to the patient share either cytochrome P450 biotransformation and permeability-glycoprotein efflux transport. In the event of cardiovascular/neuropsychiatric polypharmacy in geriatric patients, the risk of muscle severe adverse effects from pharmacokinetic drug-drug interaction should be considered beyond the direct myotoxicity of statins.

Sonographic and electrodiagnostic features of hereditary neuropathy with liability to pressure palsies

In hereditary neuropathy with liability to pressure palsies (HNPP), the increase in distal motor latencies (DMLs) is often out of proportion to the slowing of conduction velocities, but the pathophysiological mechanism is still unclear. We used a combined electrophysiological and ultrasonographic (US) approach to provide insight into this issue. Twelve HNPP subjects underwent extensive electrophysiological studies and US measurements of the cross-sectional area (CSA) of several peripheral nerves. US nerve enlargement was only observed in the carpal tunnel, Guyon's canal, the elbow and the fibular head. We did not observe US abnormalities at sites where nerve entrapment is uncommon. An increase in DMLs was observed regardless of US nerve enlargement. The increased nerve CSA only in common sites of entrapment likely reflected the well-documented nerve vulnerability to mechanical stress in HNPP. No morphometric changes were seen in the distal nerve segments where compression/entrapment is unlikely, despite the fact that the DMLs were increased. These data suggest that factors other than mechanical stress are responsible for the distal slowing of action potential propagation. We speculate that a mixture of mechanical insults and an axon-initiated process in the distal nerves underlies the distal slowing and/or conduction failure in HNPP.

Predictive factors of recovery in long thoracic mononeuropathy

The aim of the study was to identify specific factors that affect the outcome in patients with long thoracic mononeuropathy. The authors reviewed all medical records of patients with long thoracic mononeuropathy from the archive of the electromyography service over the past 16 years. Age, sex, occupation, pain at onset, symptom duration, neuropathy causes and side, and electromyography findings were collected. The outcome was evaluated by performing standard telephone interviews consisting of 9 queries about use limitations in the affected upper limb. If no limitation existed, the recovery was considered complete. If partial limitations only affected the upper limb in performing 5 or fewer of 9 specific activities, the outcome was considered good; if limitations affected more than 5 activities, the outcome was considered poor. The authors performed a multivariate logistic regression to calculate the association between good outcome or full recovery and poor outcome with demographic, clinical, and electromyography findings. Forty-one patients were included (mean±SD age, 39±14 years; 68.3% men). Causes were shoulder-arm overuse or trauma in 19 patients, iatrogenic in 5, idiopathic in 9, and inflammatory in 8. Twenty-seven patients had a good outcome and full recovery and 14 had a poor outcome. No patient underwent surgery. Age, sex, occupation, pain at onset, symptom duration, neuropathy side, and electromyography findings were not predictive of the outcome. The probability of full recovery and good outcome was 7.5 times greater in long thoracic mononeuropathy secondary to idiopathic or inflammatory causes compared with other etiologies.

Activity-dependent changes in intrinsic excitability of human spinal motoneurones produced by natural activity

The current study was designed to evaluate activity-dependent changes intrinsic to the spinal motoneurones (MNs) associated with sustained contractions. The excitability of spinal MNs (reflected by the antidromically evoked F-wave) innervating the abductor digiti minimi muscle (ADM) was measured in 12 healthy subjects following maximum voluntary contractions (MVCs) of ADM lasting 5 s, 15 s, 30 s, and 60 s. Upon cessation of the contractions, F-waves showed a depression, which increased in depth and duration with increasing duration of contraction. Following a 5-s contraction, there was a 20% decrease, which waned in 2 min, whereas a 60-s contraction produced a 40% decrease and waned in over 15 min. The changes in excitability of peripheral motor axons produced by the MVCs were measured by recording an ADM compound muscle action potential (CMAP) of ~50% of maximum to a constant ulnar nerve electrical stimulation. On cessation of the contractions, there was a prominent decrease in size of the CMAP: following a 5-s MVC, it produced a 10% decrease in the size of the test CMAP, which recovered in 2 min, whereas following a 60-s MVC, it produced a 30% decrease, which recovered in over 15 min. Statistical analysis (correntropy) showed a high-order mutual dependence between F-wave and CMAP, and both were significantly dependent on MVC duration. Because of the parallel excitability changes in peripheral axons and spinal MNs, our interpretation is that intrinsic excitability of the axon initial segment (i.e., where the action potential is generated) and peripheral axon segments changed in a similar, activity-dependent manner.

Polyneuropathy in cerebrotendinous xanthomatosis and response to treatment with chenodeoxycholic acid

Polyneuropathy has been reported in cerebrotendinous xanthomatosis (CTX), although its nature and possible association with certain genotypes and phenotypes are unclear. The effect of chronic administration of chenodeoxycholic acid (CDCA) on peripheral nerve conduction parameters is still debated. We report clinical, laboratory, and electrophysiological findings in 35 CTX patients. Twenty-six subjects (74.2 %) showed peripheral nerve abnormalities. Polyneuropathy was predominantly axonal (76.9 % of patients) and generally mild. No correlation was found between its presence and clinical or biochemical data. In polyneuropathic patients, CDCA treatment improved electrophysiological conduction parameters, irrespective of the duration of therapy. Improvement mainly concerned nerve conduction velocities, whereas most nerve amplitudes remained unchanged. This means that CDCA treatment did not influence the number of axons activated by maximum electrical stimulation but increased the conduction of the still-excitable fibers. Our findings may suggest that CDCA treatment promotes myelin synthesis in nerve fibers with residual unaffected axons. The effect of therapy may therefore depend largely on the extent of irreversible structural damage to axons.

Acute shoulder-girdle neuralgic amyotrophy (Parsonage-Turner syndrome with saphenous nerve involvement

Parsonage-Turner syndrome (PTS) is a relatively rare cause of upper extremity weakness and pain. There is currently no effective treatment for PTS although corticosteroids are recommended. Here we report the case of a man with acute PTS and exceptional involvement of both saphenous nerves, advantageously treated with intravenous immunoglobulin.

Progesterone - new therapy in mild carpal tunnel syndrome? Study design of a randomized clinical trial for local therapy

Background

Local corticosteroid injection for carpal tunnel syndrome (CTS) provides greater clinical improvement in symptoms one month after injection compared to placebo but significant symptom relief beyond one month has not been demonstrated and the relapse of symptoms is possible.

Neuroprotection and myelin repair actions of the progesterone was demonstrated in vivo and in vitro study.

We report the design of a randomized controlled trial for the local injection of cortisone versus progesterone in "mild" idiopathic CTS.

Methods

Sixty women with age between 18 and 60 years affected by "mild" idiopathic CTS, diagnosed on the basis of clinical and electrodiagnostic tests, will be enrolled in one centre. The clinical, electrophysiological and ultasonographic findings of the patients will be evaluate at baseline, 1, 6 and 12 months after injection.

The major outcome of this study is to determine whether locally-injected progesterone may be more beneficial than cortisone in CTS at clinical levels, tested with symptoms severity self-administered Boston Questionnaire and with visual analogue pain scale.

Secondary outcome measures are: duration of experimental therapy; improvement of electrodiagnostic and ultrasonographic anomalies at various follow-up; comparison of the beneficial and harmful effects of the cortisone versus progesterone.

Conclusion

We have designed a randomized controlled study to show the clinical effectiveness of local progesterone in the most frequent human focal peripheral mononeuropathy and to demonstrate the neuroprotective effects of the progesterone at the level of the peripheral nervous system in humans.

Prevalent involvement of thenar motor fibres in vineyard workers with carpal tunnel syndrome

OBJECTIVE

Carpal tunnel syndrome (CTS) has a high prevalence in agricultural workers, especially those engaged in vineyards. We postulated that vineyard CTS was electrophysiologically different from CTS of other subjects. We performed a retrospective cross-sectional electrophysiological study of two cohorts of consecutive patients with CTS, the first consisting of vineyard workers and the second, of other unselected types of workers, housewives and pensioners.

METHODS

Thirty-three vineyard workers (mean age 46.8years, 42% women) and 205 patients with other occupations (mean age 53.7years; 66% women) were enrolled. All patients underwent sensory and motor neurography of the median and ulnar nerves. Differences in demographic and electrophysiological findings between groups were calculated and multiple linear regression analysis was performed to eliminate the influence of potential confounding factors (age, sex, BMI, clinical severity of CTS) on the results of univariate difference analysis.

RESULTS

Univariate analysis showed that DML was longer and compound muscle action potential amplitude of the median nerve, recorded from the abductor pollicis brevis muscle, was smaller in vineyard workers than in the other CTS patients. These differences remained significant after adjusting the results for confounding factors.

CONCLUSIONS

The vineyard workers showed a different pattern of CTS than the other patients: thenar motor fibres were more affected, presumably due to chronic compression on the thenar branch. This suggests an association between "common" CTS and thenar mononeuropathy.

SIGNIFICANCE

Occupational physiologists should clarify the mechanisms of neuromuscular engagement in particular jobs and ergonomists design suitable working tools, because many "individual" risk factors are difficult to change, but workplace-related risk factors can be modified.