Oxaliplatin-induced Acute Neurotoxicity Recovers Between Repeat Infusion Cycles: An Axonal Excitability Repeated Multiple Measurements Study.

Background/Aim: Oxaliplatin, a platinum-based chemotherapy used in the treatment of colorectal cancer, induces acute neurotoxicity following infusion. The aim of this study was to establish whether alterations in axonal excitability develop progressively with higher cumulative doses and whether there is a recovery in motor axons after each cycle of treatment. Patients and Methods: Twenty consecutive patients with a colorectal cancer diagnosis, referred from the Oncology Department of Aretaieion Hospital of Athens, were enrolled in this study between October 2018 and May 2019. None of the participants had diabetes, alcohol abuse, known neuropathy or were previously treated with another neo-adjuvant therapy. Threshold Tracking techniques and Qtrac software were used for assessing axonal excitability in motor axons. Excitability recordings were undertaken before and immediately after the end of oxaliplatin infusion. Results: Statistically significant changes were found (p<0.01) in axonal excitability (relative refractory period, refractoriness at 2 ms and 2.5 ms, sub-excitability and super-excitability) before and after oxaliplatin infusion. No statistically significant changes (p>0.05) were found in threshold electrotonus and strength-duration parameters before and after oxaliplatin infusion. We also did not find statistically significant differences (p>0.05) between means of excitability parameters before infusion at each cycle. Conclusion: Our study confirms oxaliplatin-induced acute neurotoxicity following infusion and suggests that motor axons recover between repeat infusion cycles.

Alcohol-related peripheral neuropathy: Clinico-neurophysiological characteristics and diagnostic utility of the neuropathy symptoms score and the neuropathy impairment score.

Alcohol overconsumption is well known to cause damage to the peripheral nervous system, affecting both small and large nerve fibers. The aim of this descriptive study was to investigate peripheral nerve damage, and to correlate clinical, epidemiological and neurophysiological findings, in patients diagnosed with Alcohol Use Disorder (AUD). Ninety alcohol-dependent subjects on inpatient basis were enrolled in this prospective study over a 3-year period. Every subject was assessed by the Neuropathy Symptoms Score (NSS) questionnaire and the Neuropathy Impairment Score (NIS) clinical examination grading scale, followed by Nerve Conduction Studies, Quantitative Sensory Testing and Sympathetic Skin Response (SSR) testing. Peripheral neuropathy was diagnosed in 54 subjects (60%), by abnormal neurophysiological tests and presence of clinical signs or symptoms. Among them, pure large fiber neuropathy (LFN) was found in 18 subjects, pure small fiber neuropathy (SFN) in 12 subjects, and both large and small fiber neuropathy was diagnosed in 24 subjects. Using linear regression, we found that higher NSS and NIS scores correlated with lower amplitudes of the sural sensory nerve action potential and of the SSR. We also found a significant longer duration of alcohol abuse in subjects with neuropathy, using Student's t-test (p = 0.024). Additionally, applying NIS abnormal cut-off score ≥4, using ROC analysis, we predicted the majority of subjects with LFN, confirming 95.23% sensitivity and 93.75% specificity. Our study confirmed that peripheral neuropathy involving large and small nerve fibers, with a symmetrical length-dependent pattern, is common between patients with AUD and related to the duration of the disorder. We suggest that NSS and NIS scales could be used for the assessment of neuropathy in clinical practice, when the essential neurophysiological testing is not available.

Elevated liver enzymes and fasting glucose levels correlate with neuropathy in patients diagnosed with alcohol use disorder independently of the blood thiamine levels.

AIMS: Chronic alcohol consumption is well known to cause peripheral neuropathy, affecting both small and large nerve fibers. The aim of this study was to correlate biochemical and neurophysiological findings and investigate possible biomarkers and risk factors for pathogenetic mechanisms of neuropathy in patients diagnosed with alcohol use disorder (AUD). METHODS: Ninety patients diagnosed with AUD were enrolled in this prospective study over a period of 3 years. Serum biochemical parameters, as well as thiamine blood levels, were determined upon admission. Every subject was assessed by clinical neurological examination, followed by Nerve Conduction Studies, Quantitative Sensory Testing, and Sympathetic Skin Response. Fifty age and gender-matched patients without a diagnosis of AUD were used as the control group. RESULTS: Peripheral neuropathy was diagnosed in 54 patients (60%). Among them, pure large fiber neuropathy was found in 18 patients, pure small fiber neuropathy in 12 patients, and both large and small fiber neuropathy was diagnosed in 24 patients. Elevated liver enzymes and fasting glucose levels upon admission were significantly correlated with neuropathy. Lower blood thiamine levels (than reference) were found in seven patients and were not correlated with neuropathy. CONCLUSIONS: Our study suggests that alcohol-related liver dysfunction and hyperglycemia may contribute as risk factors of peripheral neuropathy in patients diagnosed with AUD, while blood thiamine levels do not correlate with neuropathy. Moreover, we suggest that liver enzymes and the De Ritis ratio could be potentially used as biomarkers for the incidence and severity of alcohol-related neuropathy.

Clinical significance of small nerve fiber involvement in the early diagnosis and treatment of patients with Fabry disease.

INTRODUCTION: Peripheral nervous system is early involved in Fabry disease (FD) and preferentially the small nerve fibers, causing the characteristic neuropathic pain crises usually beginning in childhood. Early detection of this likely underdiagnosed disease is an important approach because causal therapies are available. METHODS: We conducted a case-series study to investigate the small nerve fiber involvement in FD and its contribution to the diagnosis of the disease but also to the timely effective therapy administration. We used specific structured scales of symptoms and signs to detect peripheral neuropathy, as well as suitable functional and structural tests to diagnose the small fiber neuropathy (SFN). RESULTS: Twenty-seven consecutive patients (14 men, mean age 44.62 ± 10.70 years) with suspected FD were included in this study. Most of the patients presented symptoms of small nerve fiber involvement, which were accompanied by abnormal test results, fulfilling the criteria for SFN. The detection of SFN in our patients allowed the completion of the FD diagnostic criteria and thus the initiation of therapy. In five patients the SFN diagnosis determined the administration of therapy, whereas in two others it might be considered. CONCLUSION: Our results further suggest the importance of early diagnosis of peripheral neuropathy, especially of small nerve fiber involvement, in patients with suspected FD as it contributes crucially not only to the diagnosis but also to the timely effective initiation of FD therapy.

Mutational screening of Greek patients with axonal Charcot-Marie-Tooth disease using targeted next-generation sequencing: Clinical and molecular spectrum delineation.

BACKGROUND AND AIMS: Axonal forms of Charcot-Marie-Tooth disease (CMT) are classified as CMT2, distal hereditary motor neuropathy (dHMN) or hereditary sensory neuropathy (HSN) and can be caused by mutations in over 100 genes. We presently aimed to investigate for the first time the genetic landscape of axonal CMT in the Greek population. METHODS: Sixty index patients with CMT2, dHMN or HSN were screened by a combination of Sanger sequencing (GJB1) and next-generation sequencing custom-made gene panel covering 24 commonly mutated genes in axonal CMT. RESULTS: Overall, 20 variants classified as pathogenic or likely pathogenic were identified in heterozygous state in 20 index cases, representing 33.3% of the cohort. Of these, 14 were known pathogenic/likely pathogenic and six were designated as such according to ACMG classification, after in silico evaluation, testing for familial segregation and further literature review. The most frequently involved genes were GJB1 (11.7%), MPZ (5%) and MFN2 (5%), followed by DNM2 (3.3%) and LRSAM1 (3.3%). Single cases were identified with mutations in BSCL2, HSPB1 and GDAP1. INTERPRETATION: A wide phenotypic variability in terms of severity and age of onset was noted. Given the limited number of genes tested, the diagnostic yield of the present panel compares favourably with studies in other European populations. Our study delineates the genetic and phenotypic variability of inherited axonal neuropathies in the Greek population and contributes to the pathogenicity characterization of further variants linked to axonal neuropathies.

The Rise Slope of the Compound Sensory Nerve Action Potential in Normal and Pathological Human Nerves.

In spite of the diagnostic importance of the early phase of the sensory nerve action potential (SNAP), reliable electrodiagnostic metrics for this part of the recorded waveform are lacking. The average rise slope of the SNAP appreciates the steepness of the initial negative deflection of the waveform, which might be a useful metric for the first part of the potential. Sural nerve sensory neurography was performed in patients with various axonal neuropathies, and median nerve sensory studies were carried out in patients with carpal tunnel syndrome. Age-matched healthy individuals served as controls. The rise slope was compared to conventional SNAP parameters such as conduction velocity, latency, duration, and rise time. Overall, 537 sensory studies were prospectively analyzed. The rise slope of the sural SNAP demonstrated superior classification performance in terms of sensitivity (92.5%), specificity (97%), and area under the receiver operating characteristic curve (0.986), as compared to conventional SNAP parameters. Its diagnostic power was similarly excellent in median nerve studies, whereas here a slightly better classification performance was obtained by SNAP latency and conduction velocity. The average rise slope appears to do justice to the tight interplay between amplitude and rise time of the initial negative spike deflection, outperforming many conventional measures. This composite metric proved high diagnostic potency in particular with regard to axonal sensory nerve dysfunction.

Pure small fiber neuropathy in alcohol dependency detected by skin biopsy.

BACKGROUND: Alcohol overconsumption is well known to cause damage to the peripheral nervous system. The aim of this study was the functional and structural evaluation of the small nerve fibers in alcohol-dependent subjects, with or without symptoms of peripheral neuropathy. METHODS: Twenty-six consecutive alcohol-dependent subjects treated for detoxification voluntarily in the specialized unit of the Athens University Psychiatric Clinic were enrolled in this prospective study over 18 months. Every subject was assessed by peripheral nerve evaluation using the Neuropathy Symptoms Score (NSS) and Neuropathy Impairment Score (NIS), followed by nerve conduction studies (NCS), quantitative sensory testing (QST), and skin biopsy. Twenty-nine normal subjects, age- and gender-matched, constituted the control group. RESULTS: Peripheral neuropathy was diagnosed in 16 subjects (61.5%). Among these 16 subjects, pure large fiber neuropathy (LFN) was found in two subjects (12.5%), pure small fiber neuropathy (SFN) was found in eight subjects (50%), and both large and small fiber neuropathy was diagnosed in six patients (37.5%). The intraepidermal nerve fiber density (IENFD) of the patients' skin biopsy was significantly lower than that of the control group. Additionally, QST results showed a statistically significant sensory impairment in the patients. CONCLUSIONS: Our study confirms small fiber neuropathy due to alcohol abuse with a high prevalence of pure SFN that might have remained undetected without QST and IENFD.

Impaired cerebral autoregulation in Fabry disease: A case-control study.

BACKGROUND AND PURPOSE: Cerebral small vessel disease is a common manifestation among patients with Fabry disease (FD). As a biomarker of cerebral small vessel disease, the prevalence of impaired cerebral autoregulation as assessed by transcranial Doppler (TCD) ultrasonography was evaluated in FD patients and healthy controls. METHODS: TCD was performed to assess pulsatility index (PI) and vasomotor reactivity expressed by breath-holding index (BHI) for the middle cerebral arteries of included FD patients and healthy controls. Prevalence of increased PI (>1.2) and decreased BHI (<0.69) and ultrasound indices of cerebral autoregulation were compared in FD patients and controls. The potential association of ultrasound indices of impaired cerebral autoregulation with white matter lesions and leukoencephalopathy on brain MRI in FD patients was also evaluated. RESULTS: Demographics and vascular risk factors were similar in 23 FD patients (43% women, mean age: 51 ± 13 years) and 46 healthy controls (43% women, mean age: 51 ± 13 years). The prevalence of increased PI (39%; 95% confidence interval [CI]: 20%-61%), decreased BHI (39%; 95% CI: 20%-61%), and the combination of increased PI and/or decreased BHI (61%; 95% CI: 39%-80%) was significantly (p < .001) higher in FD patients compared to healthy controls (2% [95% CI: 0.1%-12%], 2% [95% CI: 0.1%-12%], and 4% [95% CI: 0.1%-15%], respectively). However, indices of abnormal cerebral autoregulation were not associated independently with white matter hyperintensities and presented a low-to-moderate predictive ability for the discrimination of FD patients with and without white matter hyperintensities. CONCLUSIONS: Impaired cerebral autoregulation as assessed by TCD appears to be highly more prevalent among FD patients compared to healthy controls.

Fabry Disease: Current and Novel Therapeutic Strategies. A Narrative Review.

BACKGROUND: Fabry disease (FD) is an inherited lysosomal storage disorder, leading to multisystemic manifestations and causing significant morbidity and mortality. OBJECTIVE: The aim of this narrative review is to present the current and novel therapeutic strategies in FD, including symptomatic and specific treatment options. METHODS: A systematic literature search was conducted to identify relevant studies, including completed and ongoing randomized-controlled clinical trials (RCTs), prospective or retrospective cohort studies, case series and case reports that provided clinical data regarding FD treatment. RESULTS: A multidisciplinary symptomatic treatment is recommended for FD patients, personalized according to disease manifestations and their severity. During the last two decades, FD-specific treatments, including two enzyme-replacement-therapies (agalsidase alfa and agalsidase beta) and chaperone treatment with migalastat have been approved for use and allowed for symptoms' stabilization or even disease burden reduction. More therapeutic agents are currently under investigation. Substrate reduction therapies, including lucerastat and venglustat, have shown promising results in RCTs and may be used either as monotherapy or as complementary therapy to established enzymereplacement- therapies. More stable enzyme-replacement-therapy molecules that are associated with less adverse events and lower likelihood of neutralizing antibodies formation have also been developed. Ex-vivo and in-vivo gene therapy is being tested in animal models and pilot human clinical trials, with preliminary results showing a favorable safety and efficacy profile. CONCLUSION: The therapeutic landscape in FD appears to be actively expanding with more treatment options expected to become available in the near future, allowing for a more personalized approach in FD patients.

D313Y Variant in Fabry Disease: A Systematic Review and Meta-analysis.

BACKGROUND AND OBJECTIVES: There is accumulating evidence in the literature indicating a strong correlation between Fabry disease (FD) phenotypes and specific sequence variations in the Galactosidase Alpha (GLA) gene. Among them, the potential pathogenicity and clinical relevance of D313Y variation in patients with FD remain debated. METHODS: We performed a systematic review and meta-analysis of studies reporting D313Y as single occurring variant in the GLA gene and sought to evaluate (1) the prevalence of D313Y variation in different populations with or without clinical manifestations of FD, (2) the clinical FD phenotype in D313Y-positive patients, and (3) the proportion of D313Y-positive patients presenting abnormal laboratory findings (alpha-galactosidase-A deficiency or globotriaosylceramide accumulation). RESULTS: Forty cohorts comprising 211 individuals with D313Y variation among 42,723 participants with available GLA gene-sequencing data were included. Patients highly suspected for FD had a higher prevalence of D313Y variation (4.9%, 95% CI 1.6%-9.9%; I2 = 95.5%) compared with the general population (0%, 95% CI 0%-0.1%; I2 = 1.9%; p = 0.004). The prevalence of D313Y variation was 0.6% (95% CI 0.3%-1%; I2 = 74.1%), 0.4% (95% CI 0.2%-0.7%; I2 = 0%), and 0.3% (95% CI 0.2%-0.4%; I2 = 0%) in patients presenting with neurologic, cardiac, or renal manifestations, respectively. D313Y was associated with a milder, late-onset FD phenotype, as indicated by the mean patient age of 51 years (95% CI 44-59; I2 = 94%) and the evidence of alpha-galactosidase A deficiency and globotriaosylceramide accumulation in 26.7% (95% CI 15.3%-40%; I2 = 34%) and 16.2% (95% CI 8%-26.4%; I2 = 35%) of cases, respectively. D313Y-positive patients displayed predominantly neurologic FD manifestations (58.1%, 95% CI 37.7%-77.1%; I2 = 78%), with central and peripheral nervous system (CNS/PNS) involvement noted in 28.2% (95% CI 15.4%-43.2%; I2 = 51%) and 28.5% (95% CI 17.8%-40.5%; I2 = 61%) of cases, respectively. DISCUSSION: D313Y variation seems to correlate with an atypical, mild late-onset phenotype with predominantly neurologic FD manifestations. Monitoring for CNS/PNS involvement is thus paramount to identify D313Y-positive patients with latent or early-FD pathology, which may qualify for enzyme-replacement therapy or chaperone treatment.

Novel Cell-Based Assay for Alpha-3 Nicotinic Receptor Antibodies Detects Antibodies Exclusively in Autoimmune Autonomic Ganglionopathy.

BACKGROUND AND OBJECTIVES: Autoantibodies against α3-subunit-containing nicotinic acetylcholine receptors (α3-nAChRs), usually measured by radioimmunoprecipitation assay (RIPA), are detected in patients with autoimmune autonomic ganglionopathy (AAG). However, low α3-nAChR antibody levels are frequently detected in other neurologic diseases with questionable significance. Our objective was to develop a method for the selective detection of the potentially pathogenic α3-nAChR antibodies, seemingly present only in patients with AAG. METHODS: The study involved sera from 55 patients from Greece, suspected for autonomic failure, and 13 patients from Italy diagnosed with autonomic failure, positive for α3-nAChR antibodies by RIPA. In addition, sera from 52 patients with Ca2+ channel or Hu antibodies and from 2,628 controls with various neuroimmune diseases were included. A sensitive live cell-based assay (CBA) with α3-nAChR-transfected cells was developed to detect antibodies against the cell-exposed α3-nAChR domain. RESULTS: Twenty-five patients were found α3-nAChR antibody positive by RIPA. Fifteen of 25 patients were also CBA positive. Of interest, all 15 CBA-positive patients had AAG, whereas all 10 CBA-negative patients had other neurologic diseases. RIPA antibody levels of the CBA-negative sera were low, although our CBA could detect dilutions of AAG sera corresponding to equally low RIPA antibody levels. No serum bound to control-transfected cells, and none of the 2,628 controls was α3-CBA positive. DISCUSSION: This study showed that in contrast to the established RIPA for α3-nAChR antibodies, which at low levels is of moderate disease specificity, our CBA seems AAG specific, while at least equally sensitive with the RIPA. This study provides Class II evidence that α3-nAChR CBA is a specific assay for AAG. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that an α3-nAChR cell-based assay is a more specific assay for AAG than the standard RIPA.

Variant transthyretin amyloidosis (ATTRv) polyneuropathy in Greece: a broad overview with a focus on non-endemic unexplored regions of the country.

Comprehensive data on variant transthyretin amyloidosis polyneuropathy (ATTRv-PN) in Greece are lacking. We presently provide an overview of ATTRv-PN in Greece, focusing on unexplored non-endemic regions of the country. In total, we identified 57 cases of ATTRv-PN diagnosed over the past 25 years, including 30 from the island of Crete, an apparent endemic region. Patients carried 10 different TTR mutations (C10R; P24S; V30M; R34G; R34T; I68L; A81T; E89Q; E89K and V94A). Carriers of the common V30M mutation constituted 54.3 % of the cohort. A known founder effect for the V30M mutation was present on the island of Crete. Non-endemic cases identified outside the island of Crete are presently reported in more detail. The age of onset ranged from 25 to 77 years, with a mean of 51.1 years. A mean diagnostic delay of 3.2 years was observed. V30M patients had earlier onset and less cardiac involvement than patients carrying other mutations. Genotype-phenotype correlations were largely consistent with published data. We conclude that, with the exception of the Cretan cluster, ATTRv-PN is not endemic in the Greek population. This makes timely diagnosis more challenging, yet absolutely essential given the availability of therapies that can alter the long-term course of the disease.

Prevalence, clinical characteristics and outcomes of Guillain-Barré syndrome spectrum associated with COVID-19: A systematic review and meta-analysis.

BACKGROUND AND PURPOSE: Mounting evidence supports an association between Guillain-Barré syndrome spectrum (GBSs) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, GBSs in the setting of coronavirus disease 2019 (COVID-19) remains poorly characterized, whilst GBSs prevalence amongst COVID-19 patients has not been previously systematically evaluated using a meta-analytical approach. METHODS: A systematic review and meta-analysis of observational cohort and case series studies reporting on the occurrence, clinical characteristics and outcomes of patients with COVID-19-associated GBSs was performed. A random-effects model was used to calculate pooled estimates and odds ratios (ORs) with corresponding 95% confidence intervals (CIs), compared to non-COVID-19, contemporary or historical GBSs patients. RESULTS: Eighteen eligible studies (11 cohorts, seven case series) were identified including a total of 136,746 COVID-19 patients. Amongst COVID-19 patients, including hospitalized and non-hospitalized cases, the pooled GBSs prevalence was 0.15‰ (95% CI 0%-0.49‰; I2  = 96%). Compared with non-infected contemporary or historical controls, patients with SARS-CoV-2 infection had increased odds for demyelinating GBSs subtypes (OR 3.27, 95% CI 1.32%-8.09%; I2  = 0%). In SARS-CoV-2-infected patients, olfactory or concomitant cranial nerve involvement was noted in 41.4% (95% CI 3.5%-60.4%; I2  = 46%) and 42.8% (95% CI 32.8%-53%; I2  = 0%) of the patients, respectively. Clinical outcomes including in-hospital mortality were comparable between COVID-19 GBSs patients and non-infected contemporary or historical GBSs controls. CONCLUSION: GBSs prevalence was estimated at 15 cases per 100,000 SARS-CoV-2 infections. COVID-19 appears to be associated with an increased likelihood of GBSs and with demyelinating GBSs variants in particular.

Vibratory testing with the 64 Hz Rydel-Seiffer tuning fork and its relation to the sural nerve action potential.

Despite its widespread use, little is known regarding the ability of the semi-quantitative Rydel-Seiffer tuning fork to designate peripheral nerve function. We sought to determine in a large sample of normal and abnormal nerves the relationship between vibration sense and compound sensory nerve action potential (SNAP) parameters recorded in a corresponding innervation area. Vibratory thresholds were determined on a scale of 0 to 8 with a 64 Hz Rydel-Seiffer tuning fork placed on the lateral malleolus of 303 subjects. Sural nerve sensory neurography was employed to derive SNAP parameters, which were related to vibration sense by means of multiple linear regression. ROC curve analysis was performed to determine the classification efficacy of the tuning fork in distinguishing normal from abnormal sural nerve responses. SNAP amplitude was the most significant predictor in the whole subjects group and in the subgroup of subjects with normal SNAPs, whereas conduction velocity played a major role in subjects with abnormal SNAPs. Age was significantly associated with vibration perception, particularly in subjects with normal SNAPs. With an area under the curve of 0.730, vibration sense was a fair classifier for decreased SNAP amplitudes. The optimal vibratory cutoff was 4.2. Age is a major determinant of vibratory test results, highlighting the importance of aging of central and peripheral pathways in mediating vibration sense. Hence, neurophysiological testing cannot be omitted in the context of polyneuropathy work-up, since even at the optimal cutoff threshold, vibratory examination still displays 40% false negative test results.

Platelet-rich Plasma and Mesenchymal Stem Cells Local Infiltration Promote Functional Recovery and Histological Repair of Experimentally Transected Sciatic Nerves in Rats.

Introduction Platelet-rich plasma (PRP) products and mesenchymal stem cells (MSCs) seem to have a significant potential as neurogenic therapeutic modulator systems. This study aimed to investigate such biological blood derivatives that could enhance nerve regeneration when applied locally in the primary repair of peripheral nerve transection of an experimental rat model. Methods A total of 42 two-month-old male Wistar rats were divided into three "treatment" groups (control, PRP, and MSCs). All the subjects were operated under anesthesia, and the surgical site was infiltrated with either normal saline, PRP derived from the animal's peripheral blood, or MSCs derived from the animal's femoral bone marrow. All three groups were also sub-divided into two sub-groups based on the post-operative administration of Non-steroidal anti-inflammatory drugs (NSAIDs) or not in order to evaluate the effect of NSAIDs on the final outcome. Three months post-surgery, electromyography evaluation of both hind limbs (right operated and left non-operated) was performed. The animals were euthanized, and nerve repair specimens were prepared for histology. Results PRP group had a significant effect (p<0.05) on the sciatic nerve repair when compared with the control group, whereas the MSC group had a positive effect but was not statistically significant (p=0.2). The number of counted neural axons at the area distal to the nerve repair site were significantly repetitive (p<0.05) in both the PRP and MSC groups when compared with the control group. Conclusions Both PRP and MSCs appear to play an essential role in the enhancement of nerve repair in terms of functionality and histology. MSCs group demonstrated a positive effect, whereas the PRP group showed statistically significant better results.

Involvement of small nerve fibres and autonomic nervous system in AL amyloidosis: comprehensive characteristics and clinical implications.

Peripheral nerve involvement in immunoglobulin light chain (AL) amyloidosis is common, characterised by severe progressive mixed neuropathy with autonomic dysfunction but there is limited data on the implications and the characteristics of small nerve fibres dysfunction (SNFD). The aim of our prospective study was to evaluate SNFD and its clinical implications in newly diagnosed AL patients. Twenty-three consecutive patients (10 male, mean age 61.78 years) and 21 age- and gender-matched healthy controls (8 male, mean age 61.28 years) underwent clinical evaluation and standard nerve conduction studies (NCS), baroreflex sensitivity (BRS) test, quantitative sensory testing (QST) and skin biopsy at the lower leg for measuring the density of the nerve fibres innervating the epidermis (IENFD). Axonal degeneration of the large nerve fibres was revealed in 15 out of 23 patients while SNFD was indicated by QST and skin biopsy in 56% and 61% of the patients respectively. BRS index significantly correlated with the IENFD and the QST results while low IENFD was associated with significantly poorer survival. Our study provides new insights and also an initial evaluation of new tools for assessment of the involvement of autonomic and small nerve fibres in AL amyloidosis. These findings also appear to have prognostic implications.

Objective Methods for Breast Sensibility Testing.

BACKGROUND: The breast and the factors that affect the sensitivity of the nipple-areola complex have been a significant subject of study in recent years. The main purpose of this study was to provide an objective assessment of the effect of volumetric differences on nipple-areola complex sensitivity. METHODS: Data were collected examining the right breast of 34 female volunteers. The mechanosensitive Aß-fiber and mechanoinsensitive C-fiber function of the nipple-areola complex was assessed after mechanical and chemical stimulation, respectively. Flare responses were elicited chemically by the application of histamine by means of iontophoresis and recorded by laser Doppler imaging. The correlation of the maximum flare area responses with the breast volume and nipple-areola complex and the response from the von Frey fiber test was estimated using linear regression analysis. RESULTS: Nipple-areola complex area increased with breast volume and, similarly, the area of histamine-induced axon reflex flare response follows the larger nipple-areola complex. However, a larger nipple-areola complex correlated with higher local mechanical thresholds. Higher mechanical thresholds were linked to smaller axon reflex area, suggesting combined small- and thick-fiber neuropathy. CONCLUSIONS: Objective small-fiber assessment using laser Doppler imaging and subjective mechanical threshold tests were used successfully to quantify function of Aß and C fibers in the nipple-areola complex. Increased breast volume was linked to larger nipples, but also to impairment of Aß and C fibers. Sensory testing can be incorporated into preoperative and postoperative management of patients undergoing breast operations to assess changes of neuronal function of the nipple-areola complex after surgery.

Diagnostic Accuracy of Muscle Biopsy and Electromyography in 123 Patients with Neuromuscular Disorders.

BACKGROUND/AIM: Diagnostic accuracy of muscle biopsy and electromyography (EMG) in patients with myopathy varies widely among studies. The goal of this study was to examine the diagnostic accuracy of each method in the diagnosis of patients with suspected myopathy, and determine the level of agreement between the two methods. PATIENTS AND METHODS: The files of all patients with a presumed myopathy were retrospectively reviewed. All patients with detailed muscle biopsy and EMG data were included. RESULTS: A total of 123 patients were included. Accuracy of biopsy was 80.4% compared to 70.7% for EMG. Biopsy was sensitive and specific in all neuromuscular disorders. EMG was accurate in neurogenic disorders. Biopsy and EMG agreement was 70.7%. CONCLUSION: Muscle biopsy is more accurate than EMG in patients with myopathy. Muscle biopsy-EMG discordance can be attributed to different muscle sampling and to disorders with both neurogenic and myopathic features, such as acquired and mitochondrial myopathies.