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Introduction/aims: Corneal confocal microscopy (CCM) detects small nerve fiber loss and correlates with skin biopsy findings in diabetic neuropathy. In chronic idiopathic axonal polyneuropathy (CIAP) this correlation is unknown. Therefore, we compared CCM and skin biopsy in patients with CIAP to healthy controls, patients with painful diabetic neuropathy (PDN) and diabetics without overt neuropathy (DM)., Methods: Participants with CIAP and suspected small fiber neuropathy (n = 15), PDN (n = 16), DM (n = 15), and healthy controls (n = 16) underwent skin biopsy and CCM testing. Inter-center intraclass correlation coefficients (ICC) were calculated for CCM parameters., Results: Compared with healthy controls, patients with CIAP and PDN had significantly fewer nerve fibers in the skin (IENFD: 5.7 ± 2.3, 3.0 ± 1.8, 3.9 ± 1.5 fibers/mm, all p < .05). Corneal nerve parameters in CIAP (fiber density 23.8 ± 4.9 no./mm 2 , branch density 16.0 ± 8.8 no./mm 2 , fiber length 13.1 ± 2.6 mm/mm 2 ) were not different from healthy controls (24.0 ± 6.8 no./mm 2 , 22.1 ± 9.7 no./mm 2 , 13.5 ± 3.5 mm/mm 2 , all p > .05). In patients with PDN, corneal nerve fiber density (17.8 ± 5.7 no./mm 2 ) and fiber length (10.5 ± 2.7 mm/mm 2 ) were reduced compared with healthy controls (p < .05). CCM results did not correlate with IENFD in CIAP patients. Inter-center ICC was 0.77 for fiber density and 0.87 for fiber length., Discussion: In contrast to patients with PDN, corneal nerve parameters were not decreased in patients with CIAP and small nerve fiber damage. Therefore, CCM is not a good biomarker for small nerve fiber loss in CIAP patients., (© 2024 The Author(s). Muscle & Nerve published by Wiley Periodicals LLC.)

Extracellular vesicles (EVs), exhibiting their functional activity after internalization by recipient cells, are involved in the pathogenesis of drug-induced polyneuropathy (DIPN), a common complication of antitumor therapy. In this work, the internalization of EVs obtained from colorectal cancer patients undergoing polychemotherapy and its relationship with neurotoxicity were assessed using a model system of mononuclear leukocytes. Circulating EVs were isolated from 8 colorectal cancer patients who received antitumor therapy according to the FOLFOX or XELOX regimens before the start of chemotherapy (point 1) and after 3-4 courses (point 2). Mononuclear leukocytes of a healthy donor served as a cellular model system for EV internalization in vitro. EV internalization was assessed using fluorescence microscopy. It was shown that internalization of EVs obtained from colorectal cancer patients with high neurotoxicity was higher than in the group with low neurotoxicity. The ability of CD11b-positive (CD11b⁺) and CD11b-negative (CD11b⁻) mononuclear leukocytes of a healthy donor to internalize EVs obtained from patients before and after chemotherapy did not reveal significant differences. A direct relationship was found between the relative number of CD11b⁻ cells with internalized EVs and the integral index of neurotoxicity according to the NRS scale at the peak of its manifestation (point 2) (r=0.675, p.

Objective: To evaluate serum neurofilament light chain (sNfL) as biomarker of disease onset, progression and treatment effect in hereditary transthyretin (ATTRv) amyloidosis patients and TTR variant ( TTR v) carriers., Methods: sNfL levels were assessed longitudinally in persistently asymptomatic TTR v carriers ( N  = 12), persistently asymptomatic ATTRv amyloidosis patients (defined as asymptomatic patients but with amyloid detectable in subcutaneous abdominal fat tissue) ( N  = 8), in TTR v carriers who developed polyneuropathy ( N  = 7) and in ATTRv amyloidosis patients with polyneuropathy on treatment (TTR-stabiliser ( N  = 20) or TTR-silencer ( N  = 18)). Polyneuropathy was confirmed by nerve conduction studies or quantitative sensory testing. sNfL was analysed using a single-molecule array assay., Results: sNfL increased over 2 years in persistently asymptomatic ATTRv amyloidosis patients, but did not change in persistently asymptomatic TTR v carriers. In all TTR v carriers who developed polyneuropathy, sNfL increased from 8.4 to 49.8 pg/mL before the onset of symptoms and before polyneuropathy could be confirmed neurophysiologically. In symptomatic ATTRv amyloidosis patients on a TTR-stabiliser, sNfL remained stable over 2 years. In patients on a TTR-silencer, sNfL decreased after 1 year of treatment., Conclusion: sNfL is a biomarker of early neuronal damage in ATTRv amyloidosis already before the onset of polyneuropathy. Current data support the use of sNfL in screening asymptomatic TTR v carriers and in monitoring of disease progression and treatment effect.

Background: PHARC syndrome (MIM:612674) is a rare neurodegenerative disorder characterized by demyelinating polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and cataracts (PHARC). The syndrome is caused by mutations in the ABHD12 gene, which encodes αβ-hydrolase domain-containing protein 12 related to endocannabinoid metabolism. PHARC syndrome is one of the rare diseases; so far, only 51 patients have been reported in the literature., Methods: We evaluated the 25-year-old male patient referred to us due to vision loss, cataracts, and hearing loss. Ophthalmological examinations and genetic analyses were performed using targeted next-generation sequencing., Results: In the genetic analysis, the patient was diagnosed with PHARC syndrome by detecting homozygous (NM&#95;001042472.3): c.871del (p.Tyr291IlefsTer28) novel pathogenic variation in the ABHD12 gene. Following the molecular diagnosis, he was referred to the neurology department for reverse phenotyping and sensorimotor demyelinating polyneuropathy was detected in the neurological evaluation., Conclusions: In this study, we report a novel variation in ABHD12 gene in the first Turkish-origin PHARC patient. We present this study to contribute genotype-phenotype correlation of PHARC syndrome and emphasize the importance of molecular genetic diagnosis in order to determine the appropriate clinical approach. This report is essential for expanding the phenotypic spectrum in different populations and understanding the genotype-phenotype correlation of PHARC syndrome via novel pathogenic variation in the ABHD12 gene.

Background and Objectives: Hereditary spastic paraplegias (HSPs) are heterogenous genetic disorders. While peripheral nerve involvement is frequent in spastic paraplegia 7 (SPG7), the evidence of peripheral nerve involvement in SPG4 is more controversial. We aimed to characterize lower extremity peripheral nerve involvement in SPG4 and SPG7 by quantitative magnetic resonance neurography (MRN)., Methods: Twenty-six HSP patients carrying either the SPG4 or SPG7 mutation and 26 age-/sex-matched healthy controls prospectively underwent high-resolution MRN with large coverage of the sciatic and tibial nerve. Dual-echo turbo-spin-echo sequences with spectral fat-saturation were utilized for T2-relaxometry and morphometric quantification, while two gradient-echo sequences with and without an off-resonance saturation rapid frequency pulse were applied for magnetization transfer contrast (MTC) imaging. HSP patients additionally underwent detailed neurologic and electroneurographic assessments., Results: All microstructural (proton spin density [ρ], T2-relaxation time, magnetization transfer ratio) and morphometric (cross-sectional area) quantitative MRN markers were decreased in SPG4 and SPG7 indicating chronic axonopathy. ρ was superior in differentiating subgroups and identifying subclinical nerve damage in SPG4 and SPG7 without neurophysiologic signs of polyneuropathy. MRN markers correlated well with clinical scores and electroneurographic results., Conclusions: MRN characterizes peripheral nerve involvement in SPG4 and SPG7 as a neuropathy with predominant axonal loss. Evidence of peripheral nerve involvement in SPG4 and SPG7, even without electroneurographically manifest polyneuropathy, and the good correlation of MRN markers with clinical measures of disease progression, challenge the traditional view of the existence of HSPs with isolated pyramidal signs and suggest MRN markers as potential progression biomarkers in HSP., (© 2023 The Authors. European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.)

Objective: The objective was to analyze the clinical characteristics and pathological characteristics of sural biopsy in nitrous oxide (N2O) -induced peripheral neuropathy., Methods: We recruited 18 patients with N2O abuse-induced neurological disorders and reported their demographic data, clinical manifestations, laboratory examinations, and nerve conduction studies. Seven patients underwent sural nerve biopsy pathologic examination., Results: All 18 patients had polyneuropathy, the nerve conduction results showed significant reductions in motor and sensory amplitudes, slowing of conduction velocities, and prolongation of latencies in most tested nerves compared to the controls. Toluidine blue staining of semi-thin sections of sural nerve biopsy showed decreased myelinated nerve fiber density, increased thin myelinated nerve fiber density, and axonal regeneration. Electron microscopy showed axonal degeneration and nerve regeneration., Conclusion: The main manifestations of peripheral nerve damage caused by the abuse of N2O are lower limb weakness and distal sensory disorder. The nerve conduction study results demonstrated that mixed axonal and demyelinating neuropathy was the most common type of neuropathy. Sural biopsy showed the main pathological change was chronic axonal degeneration., Competing Interests: The authors declare that they have no competing interests.

Familial amyloid polyneuropathy (FAP) caused by a genetic mutation in transthyretin (TTR) is an autosomal dominant hereditary disease. The retrospective, observational case series study presents the ocular clinicopathological findings of five cases carrying the TTR mutation c.401A>G (p.Tyr134Cys). Multimodal retinal imaging and electrophysiological examination, Congo red staining and immunohistochemical analysis of specimens, and genetic analyses were performed. Cases 1 and 2 were symptomatic with vitreous and retinal amyloid deposition and poor visual recovery. Case 3 had a symptomatic vitreous haze in the left eye with good postoperative visual recovery. The right eye of case 3 and the eyes of cases 4 and 5 were asymptomatic. Thicker retinal nerve fiber layer, retinal venous tortuosity with prolonged arteriovenous passage time on fluorescein angiography and retinal dysfunction detected by multifocal electroretinogram occurred even in asymptomatic eyes. Moreover, the internal limiting membrane from patients with FAP was stained positive for Congo red and transforming growth factor-β1. The results highlight the amyloid deposition of mutant TTR in the optic disc and retina, even in the asymptomatic stage. The deposited amyloid leads to increased resistance to venous return and retinal functional abnormalities. Therefore, careful follow-up of structural and functional changes in the retina is needed, even in asymptomatic patients with FAP.

Objective: Thalamus is essential in processing of sensory information. This study explored the associations between thalamic volume and intra-thalamic metabolites and associations to clinical and experimental characteristics of sensory function in adults with diabetic polyneuropathy., Methods: 48 adults with type 1 diabetes and confirmed distal symmetric peripheral neuropathy (DPSN) and 28 healthy controls participated in a cross-sectional study and underwent a brain magnetic resonance imaging scan. Estimates for thalamic volume were extracted using voxel-based morphometry and intra-thalamic N-acetylaspartate/creatine (NAA/cre) levels were assessed by magnetic resonance spectroscopy. Associations between thalamic volume and clinical measures, quantitative sensory testing and neuropathic phenotype were explored., Results: In diabetes, reduced gray matter volume was identified including bilateral thalamus (all p≤0.001) in comparison to healthy participants. Thalamic volume estimates were positively associated to intra-thalamic NAA/cre (r=0.4; p=0.006), however not to diabetes duration (p=0.5), severity of DSPN (p=0.7), or presence of pain (p=0.3). Individuals with the lowest thalamic volume had greatest loss of protective sensation (light touch using von Frey-like filaments, p=0.037) and highest pain tolerance to electric stimulation (tetanic stimulation, p=0.008) compared to individuals with the highest thalamic volume., Conclusions: In this cohort with type 1 diabetes and severe DSPN, thalamic atrophy was present and associated with reduced NAA/cre, indicating thalamic structural loss and dysfunction. Thalamic atrophy was associated to reduced sensory function involving large fiber neuropathy and sensation to tetanic stimulation that may reflect synaptic transmission. This may ultimately contribute to the current understanding of the pathophysiology behind the perception changes evident in DSPN., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Background: Tongue atrophy with wrinkling as a clinical sign of inherited polyneuropathies has not been reported in dogs., Objectives: Clinically describe tongue atrophy as well as morphology of the tongue and hypoglossal nerve in Alaskan malamute polyneuropathy (AMPN)., Animals: Six client-owned Alaskan malamute dogs diagnosed with AMPN, all homozygous for the causative mutation in the N-myc downstream-regulated gene 1 (NDRG1) and 1 neurologically normal control Alaskan malamute., Methods: Prospective case study. Clinical and neurological examinations were performed on affected dogs. Necropsy samples from the tongue muscle and hypoglossal nerve were examined by light and electron microscopy., Results: All affected dogs had abnormal wrinkles and grooves on the dorsal surface of the tongue, a clinical sign not described previously in dogs with AMPN. Electromyography of the tongue performed in 2 dogs showed spontaneous activity. Five affected dogs underwent necropsy studies. Histopathology of the tongue showed groups of angular atrophic myofibers and changes in the hypoglossal nerve included thinly myelinated fibers, small onion bulbs, folded myelin, and axonal degeneration., Conclusion and Clinical Importance: Histopathologic changes in the tongue and hypoglossal nerve were consistent with previously reported changes in skeletal muscle and other nerves from dogs with AMPN. Therefore, we conclude that macroscopic tongue atrophy is part of the disease phenotype of AMPN and should be considered a potential clinical sign in dogs with polyneuropathies., (© 2022 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Introduction: Pure Neural Leprosy (PNL) is a rare clinical form of leprosy in which patients do not present with the classical skin lesions but have a high burden of the disability associated with the disease. Clinical characteristics and follow up of patients in PNL are still poorly described in the literature., Objective: This paper aims to describe the clinical, electrophysiological and histopathological characteristics of PNL patients, as well as their evolution after multidrug therapy (MDT)., Methods: Fifty-two PNL patients were selected. Clinical, nerve conduction studies (NCS), histopathological and anti-PGL-1serology were evaluated. Patients were also assessed monthly during the MDT. At the end of the MDT, all of the patients had a new neurological examination and 44 were submitted to another NCS., Results: Paresthesia was the complaint most frequently reported by patients, and in the neurological examination the most common pattern observed was impairment in sensory and motor examination and a mononeuropathy multiplex. Painful nerve enlargement, a classical symptom of leprosy neuropathy, was observed in a minority of patients and in the motor NCS axonal injuries, alone or in combination with demyelinating features, were the most commonly observed. 88% of the patients did not present any leprosy reaction during MDT. There was no statistically significant difference between the neurological examinations, nor the NCS pattern, performed before and after the MDT., Discussion: The classical hallmarks of leprosy neuropathy are not always present in PNL making the diagnosis even more challenging. Nerve biopsy is an important tool for PNL diagnosis as it may guide therapeutic decisions. This paper highlights unique characteristics of PNL in the spectrum of leprosy in an attempt to facilitate the diagnosis and management of these patients., Competing Interests: The authors have declared that no competing interests exist.

Pathogenic variants in SETX cause two distinct neurological diseases, a loss-of-function recessive disorder, ataxia with oculomotor apraxia type 2 (AOA2), and a dominant gain-of-function motor neuron disorder, amyotrophic lateral sclerosis type 4 (ALS4). We identified two unrelated patients with the same de novo c.23C > T (p.Thr8Met) variant in SETX presenting with an early-onset, severe polyneuropathy. As rare private gene variation is often difficult to link to genetic neurological disease by DNA sequence alone, we used transcriptional network analysis to functionally validate these patients with severe de novo SETX-related neurodegenerative disorder. Weighted gene co-expression network analysis (WGCNA) was used to identify disease-associated modules from two different ALS4 mouse models and compared to confirmed ALS4 patient data to derive an ALS4-specific transcriptional signature. WGCNA of whole blood RNA-sequencing data from a patient with the p.Thr8Met SETX variant was compared to ALS4 and control patients to determine if this signature could be used to identify affected patients. WGCNA identified overlapping disease-associated modules in ALS4 mouse model data and ALS4 patient data. Mouse ALS4 disease-associated modules were not associated with AOA2 disease modules, confirming distinct disease-specific signatures. The expression profile of a patient carrying the c.23C > T (p.Thr8Met) variant was significantly associated with the human and mouse ALS4 signature, confirming the relationship between this SETX variant and disease. The similar clinical presentations of the two unrelated patients with the same de novo p.Thr8Met variant and the functional data provide strong evidence that the p.Thr8Met variant is pathogenic. The distinct phenotype expands the clinical spectrum of SETX-related disorders., (© 2021. The Author(s).)

This study investigated the phenotypic spectrum of PHARC (polyneuropathy, hearing loss, ataxia, retinitis pigmentosa and early-onset cataract) syndrome caused by biallelic variants in the ABHD12 gene. A total of 15 patients from 12 different families were included, with a mean age of 36.7 years (standard deviation [SD] ± 11.0; range from 17.5 to 53.9) at the most recent examination. The presence and onset of neurological, audiological and ophthalmic symptoms were variable, with no evident order of symptom appearance. The mean best-corrected visual acuity was 1.1 logMAR (SD ± 0.9; range from 0.1 to 2.8; equivalent to 20/250 Snellen) and showed a trend of progressive decline. Different types of cataract were observed in 13 out of 15 patients (87%), which also included congenital forms of cataract. Fundus examination revealed macular involvement in all patients, ranging from alterations of the retinal pigment epithelium to macular atrophy. Intraretinal spicular hyperpigmentation was observed in 7 out of 15 patients (47%). From an ophthalmic perspective, clinical manifestations in patients with PHARC demonstrate variability with regard to their onset and severity. Given the variable nature of PHARC, an early multidisciplinary assessment is recommended to assess disease severity.

Immune checkpoint inhibitors (ICIs) have been increasingly used in the treatment of various types of tumors with favorable results. But these treatments also led to a variety of immune-related adverse events (irAEs). Neurological irAEs such as Guillain-Barré Syndrome are rare and may have serious consequences once they occur. A systematic literature search was performed in PubMed and Embase for all case reports of GBS associated with ICIs published in English reporting on human beings from 1990 up to date. A total of 30 case reports (total patients = 33) were used for final analysis. The included cases were from 11 countries, covering 10 tumor types, with melanoma accounting for the largest number. The mean age was 62.2 ± 11.1 years old, and males were dominant (male: 26 and female: 7). The median time of initial symptoms was 8.2 weeks after the 1 st dose of ICIs. The most common manifestations of GBS associated with ICIs were weakness, hyporeflexia or areflexia, and paresthesia in order. The GBS subtypes suggested by electrophysiological results were acute inflammatory demyelinating polyneuropathy (AIDP), acute motor axonal neuropathy (AMAN), and Miller Fisher syndrome (MFS). The protein level of CSF in patients with GBS related to ICIs was 180.68 ± 152.51 mg/dl. Immediate termination of ICIs followed by intravenous immunoglobulin was the preferred treatment option. 72.7% of patients recovered or had residual mild dysfunction after treatment. Elderly male patients with melanoma were most likely to develop ICI-related GBS. The specific neurological symptoms, CSF analysis, and electrophysiological examination were important means of diagnosis., Competing Interests: The authors have no conflicts of interest to declare., (Copyright © 2021 Yan Li et al.)

Acute hepatic porphyrias are inherited metabolic disorders that may present with polyneuropathy, which if not diagnosed early can lead to quadriparesis, respiratory weakness, and death. Porphyric neuropathy is an acute to subacute motor predominant axonal neuropathy with a predilection for the upper extremities and usually preceded by a predominantly parasympathetic autonomic neuropathy. The rapid progression and associated dysautonomia mimic Guillain-Barré syndrome but are distinguished by the absence of cerebrospinal fluid albuminocytologic dissociation, progression beyond 4 wk, and associated abdominal pain. Spot urine test to assess the porphyrin precursors delta-aminolevulinic acid and porphobilinogen can provide a timely diagnosis during an acute attack. Timely treatment with intravenous heme, carbohydrate loading, and avoidance of porphyrinogenic medications can prevent further neurological morbidity and mortality., (© 2021 Wiley Periodicals LLC.)

Multifocal motor neuropathy (MMN) is a rare disease with a prevalence of less than 1 per 100,000 people. Intravenous immunoglobulin (IVIG) therapy, performed for a long-term period, has been demonstrated able to improve the clinical picture of MMN patients, ameliorating motor symptoms and/or preventing disease progression. Treatment with subcutaneous immunoglobulin (SCIg) has been shown to be as effective as IVIG. However, previously published data showed that follow-up of MMN patients in treatment with SCIg lasted no more than 56 months. We report herein the results of a long-term SCIg treatment follow up (up to 96 months) in a group of 8 MMN patients (6 M; 2F), previously stabilized with IVIG therapy. Clinical follow-up included the administration of Medical Research Council (MRC) sum-score, the Overall Neuropathy Limitation Scale (ONLS) and the Life Quality Index questionnaire (LQI) at baseline and then every 6 months. Once converted to SCIg, patients' responsiveness was quite good. Strength and motor functions remained stable or even improved during this long-term follow-up with benefits on walking capability, resistance to physical efforts and ability in hand fine movements.

Background: We aimed to describe the electrophysiological progression rate of chronic idiopathic axonal polyneuropathy (CIAP) and look into the potential role of human leukocyte antigen (HLA) genetic susceptibility in its development., Methods: We recruited 57 patients with CIAP (mean age at diagnosis 67, mean follow-up 7 years). The assessments included clinical and electrophysiological data and HLA-DQ genotyping., Results: The DQA1*05 allele was found more frequently in patients than in healthy controls (odds ratio, 1.96, P = .011). In patients with length-dependent CIAP, a linear effect of time on the electrophysiological findings was found in the superficial radial (3.2% mean annual decrement, P < .001), sural (4.7% mean annual decrement, P = .002) and tibial nerve (6.1% mean annual decrement, P = .007) amplitudes, independently from age or gender., Conclusions: Patients with length-dependent CIAP, show a linear progression over time. Interesting associations of HLA-DQA1*05 allele with length-dependent CIAP and non-DQ2/DQ8 with idiopathic sensory ganglionopathy were found. These merit further investigation in larger cohorts and may suggest a role of the immune system in the pathogenesis of CIAP., (© 2021 Wiley Periodicals LLC.)

Objective: To study serum neurofilament light chain (sNfL) in amyloid light chain (AL) amyloidosis patients with and without polyneuropathy (PNP) and to corroborate previous observations that sNfL is increased in hereditary transthyretin-related (ATTRv) amyloidosis patients with PNP., Methods: sNfL levels were assessed retrospectively in patients with AL amyloidosis with and without PNP (AL/PNP+ and AL/PNP-, respectively), patients with ATTRv amyloidosis and PNP (ATTRv/PNP+), asymptomatic transthyretin ( TTR) gene mutation carriers ( TTR v carriers) and healthy controls. Healthy controls (HC) were age- and sex-matched to both AL/PNP- (HC/AL) and TTR v carriers (HC/ TTR v). The single-molecule array (Simoa) assay was used to assess sNfL levels., Results: sNfL levels were increased both in 10 AL/PNP+ patients ( p  < .001) and in 10 AL/PNP- patients ( p  < .005) compared to 10 HC/AL individuals. sNfL levels were higher in AL/PNP+ patients than in AL/PNP- patients ( p  < .005). sNfL levels were also increased in 15 ATTRv/PNP+ patients, compared to both 15 HC/ TTR v ( p  < .0001) and 15 TTR v carriers ( p  < .0001). ATTRv/PNP+ patients with progressive PNP (PND-score > I) had the highest sNfL levels compared to patients with early PNP (PND-score I) ( p  = .05). sNfL levels did not differ between TTR v carriers and HC/ TTR v individuals. In the group comprising all healthy controls and in the group of TTR v carriers, sNfL levels correlated with age., Conclusion: sNfL levels are increased in patients with PNP in both AL and ATTRv amyloidosis and are related to severity of PNP in ATTRv amyloidosis. sNfL is a promising biomarker to detect PNP, not only in ATTRv but also in AL amyloidosis.

Background: Mutations in the GNE gene have been so far described as predominantly associated with distal lower-limb myopathies. Recent reports describe mutations in this gene in patients with peripheral neuropathy and motor neuron disease., Methods: We describe three patients displaying motor neuropathy in association with GNE mutations. Clinical, electrophysiological, imaging, pathological, and genetic data are presented in a retrospective manner., Results: The three patients had different phenotypes, ranging from mildly progressive lower limb weakness to a rapidly progressive 4-limb weakness. Genetic testing revealed GNE gene mutations in all patients; of those mutations, p.(His186Arg) has not been previously reported. All patients showed evidence of axonal motor nerve involvement on electrodiagnostic examination and/or muscle biopsy., Conclusions: Nerve involvement associated with GNE gene mutations may be an underdiagnosed pathology and may influence clinical presentation and disease progression., (© 2020 Wiley Periodicals LLC.)

Background: Despite its initial association with sensory neuropathies, anti-fibroblast growth factor receptor 3 (FGFR3) antibodies have been since reported with a broad range of neuropathies and clinical features. The aim of the study is to report the clinical and electro diagnostic findings in a cohort of patients with sensory or sensorimotor polyneuropathy and anti-FGFR3 antibodies., Methods: We performed a retrospective chart review to assess the clinical characteristics of patients with sensory or sensorimotor neuropathy related to FGFR3 antibodies. Descriptive statistics were reported using frequencies and percentages for categorical variables and median and interquartile range (IQR) for continuous variables., Results: This study included 14 patients (9 women) with a median age of 51.9 years (IQR 48-57). The most common presenting symptoms were painful paresthesia (100%), gait instability (42.9%), constitutional symptoms (42.9%), and autonomic symptoms (28.6%). Onset of symptoms was chronic (≥12 weeks) in eight patients (57.1%). Examination showed a distal loss of sensation to pin prick (100%), as well as impaired vibration sensation (78.6%) and proprioception (35.7%), in the distal extremities. We also observed mild weakness in the distal lower-extremities (42.9%). Three patients (21.4%) had trigeminal neuralgia, three patients (21.4%) had co-existing autoimmune disease, and one patient (7.1%) had a history of renal cell carcinoma. The mean titer of FGFR3 antibody was 14,285.71 (IQR 5000-16,750). All 14 patients produced normal results in the neuropathy workup. Nerve conduction study and electromyography showed sensory axonal neuropathy in four patients (28.6%), sensorimotor axonal neuropathy in seven patients (50%), and a normal result in three patients (21.4%). For those with a normal NCS/EMG, a skin biopsy showed a non-length-dependent small fiber neuropathy., Conclusions: Neuropathy related to FGFR3 antibodies can potentially involve small and large fibers, sensory and motor fibers, and even the trigeminal nerve, which contributes to a highly variable clinical presentation.

Background: We aimed to compare neuropathic progression rate between hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) and other peripheral neuropathies, including diabetic peripheral neuropathy (DPN) and Charcot-Marie-Tooth disease (CMT)., Methods: Literature searches identified studies reporting neuropathic progression, measured by Neuropathy Impairment Score (NIS) or NIS-Lower Limbs (NIS-LL). Our study also included unpublished data from a clinical registry of patients who were diagnosed with different peripheral neuropathies and seen at the Oregon Health & Science University (OHSU) during 2016-2020. Meta-analysis and meta-regression models examined and compared annual progression rates, calculated from extracted data, between studies of ATTRv-PN and other peripheral neuropathies., Results: Data were synthesized from 15 studies in which NIS and/or NIS-LL total scores were assessed at least twice, with ≥12 weeks between assessments, among untreated patients with ATTRv-PN or other peripheral neuropathies. Meta-analysis models yielded that the annual progression rate in NIS total scores was significantly different from zero for studies in ATTRv-PN and CMT (11.77 and 1.41; both P < 0.001), but not DPN (- 1.96; P = 0.147). Meta-regression models showed significantly faster annual progression in studies in ATTRv-PN, which statistically exceeded that in other peripheral neuropathies by 12.45 points/year for NIS, and 6.96 for NIS-LL (both P < 0.001)., Conclusions: Peripheral nervous function deteriorates more rapidly in patients with ATTRv-PN than for other peripheral neuropathies. These findings may improve understanding of the natural history of neuropathy in ATTRv-PN, facilitate early diagnosis, and guide the development of assessment tools and therapies specifically targeting neuropathic progression in this debilitating disease.

Development of peripheral nervous system (PNS) myelin involves a coordinated series of events between growing axons and the Schwann cell (SC) progenitors that will eventually ensheath them. Myelin sheaths have evolved out of necessity to maintain rapid impulse propagation while accounting for body space constraints. However, myelinating SCs perform additional critical functions that are required to preserve axonal integrity including mitigating energy consumption by establishing the nodal architecture, regulating axon caliber by organizing axonal cytoskeleton networks, providing trophic and potentially metabolic support, possibly supplying genetic translation materials and protecting axons from toxic insults. The intermediate steps between the loss of these functions and the initiation of axon degeneration are unknown but the importance of these processes provides insightful clues. Prevalent demyelinating diseases of the PNS include the inherited neuropathies Charcot-Marie-Tooth Disease, Type 1 (CMT1) and Hereditary Neuropathy with Liability to Pressure Palsies (HNPP) and the inflammatory diseases Acute Inflammatory Demyelinating Polyneuropathy (AIDP) and Chronic Inflammatory Demyelinating Polyneuropathy (CIDP). Secondary axon degeneration is a common feature of demyelinating neuropathies and this process is often correlated with clinical deficits and long-lasting disability in patients. There is abundant electrophysiological and histological evidence for secondary axon degeneration in patients and rodent models of PNS demyelinating diseases. Fully understanding the involvement of secondary axon degeneration in these diseases is essential for expanding our knowledge of disease pathogenesis and prognosis, which will be essential for developing novel therapeutic strategies., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Introduction: ATTRv amyloidosis is worldwide spread with endemic foci in Portugal and Sweden, Japan, Brazil, Maiorca, and Cyprus. A national Registry was developed to characterise the epidemiology and genotype-phenotype correlation of ATTRv amyloidosis in Italy and to allow a better planning of diagnostic and therapeutic services., Methods: Fifteen Italian referral centres for amyloidosis spread all over the country have contributed to the Registry., Results: Four-hundred-forty-seven subjects were enrolled, 187 asymptomatic carriers and 260 affected patients. Thirty-one different mutations were recorded. The seven most represented genetic variants were significantly different in terms of age at onset, clinical features and geographical distribution. National prevalence is 4.33/million with higher values in Southern Italy. Overall symptoms of polyneuropathy were present at disease onset in about half of the patients, symptoms of cardiomyopathy in a quarter of patients, the rest referring carpal tunnel syndrome, dysautonomia or lumbar spinal stenosis. 52.6% of patients were in FAP stage 1, 20.4% in stage 2 and 13.5% in stage 3, while 13.5% patients had no neuropathy, presenting only cardiological symptoms., Conclusions: We presented an epidemiological study based on collaboration among referral centres for ATTRv amyloidosis spread in all the Italian territory, using web-based Registry. It provided a detailed map of the regional distribution of the disease. The increased awareness of the disease among general practitioners and medical specialists has contributed to reduce the diagnostic delay and the rate of misdiagnosis. The Registry will allow to collect also future information about clinical and instrumental follow-up.

Objective: To present standardized diagnostic criteria for idiopathic distal sensory polyneuropathy (iDSP) and its subtypes: idiopathic mixed fiber sensory neuropathy (iMFN), idiopathic small fiber sensory neuropathy (iSFN), and idiopathic large fiber sensory neuropathy (iLFN) for use in research., Methods: The Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities and Networks (ACTTION) public-private partnership with the Food and Drug Administration convened a meeting to develop consensus diagnostic criteria for iMFN, iSFN, and iLFN. After background presentations, a collaborative, iterative approach was used to develop expert consensus for new criteria., Results: An iDSP diagnosis requires at least 1 small fiber (SF) or large fiber (LF) symptom, at least 1 SF or LF sign, abnormalities in sensory nerve conduction studies (NCS) or distal intraepidermal nerve fiber density (IENFD), and exclusion of known etiologies. An iMFN diagnosis requires that at least 1 of the above clinical features is SF and 1 clinical feature is LF with abnormalities in sensory NCS or IENFD. Diagnostic criteria for iSFN require at least 1 SF symptom and at least 1 SF sign with abnormal IENFD, normal sensory NCS, and the absence of LF symptoms and signs. Diagnostic criteria for iLFN require at least 1 LF symptom and at least 1 LF sign with normal IENFD, abnormal sensory NCS, and absence of SF symptoms and signs., Conclusion: Adoption of these standardized diagnostic criteria will advance research and clinical trials and spur development of novel therapies for iDSPs., (© 2020 American Academy of Neurology.)

The aim of this study was to evaluate the presence and characterization of chemotherapy-induced neuropathy (CIPN) and neuropathic pain 5 years after adjuvant chemotherapy with docetaxel or oxaliplatin. Patients from an ongoing prospective study, who had received adjuvant chemotherapy with docetaxel or oxaliplatin in 2011 to 2012 were invited to participate. The patients underwent a thorough examination with interview, neurological examination, questionnaires, assessment tools, nerve conduction studies (NCS), quantitative sensory testing, MScan motor unit number estimation (MUNE), and corneal confocal microscopy (CCM). Patients were divided into no, possible, probable, and confirmed CIPN. Out of the 132 eligible patients, 63 agreed to participate: 28 had received docetaxel and 35 had received oxaliplatin. Forty-one percent had confirmed CIPN, 34% possible or probable CIPN, and 22% did not have CIPN. The CIPN was characterized mainly by sensory nerve fiber loss, with a more pronounced large fiber than small fiber loss but also some motor fiber loss identified on NCS and MUNE. In general, patients had mild neuropathy with relatively low scores on assessment tools and no association with mood and quality of life. CCM was not useful as a diagnostic tool. Of the patients with probable or confirmed CIPN, 30% experienced pain, which was most often mild, but still interfered moderately with daily life in 20% to 25% and was associated with lower quality of life. In conclusion CIPN was confirmed in 41% 5 years after chemotherapy. The neuropathy was generally mild, but in patients with neuropathic pain it was associated with lower quality of life., (© 2020 The Authors. Journal of the Peripheral Nervous System published by Wiley Periodicals LLC on behalf of Peripheral Nerve Society.)

The nuclear membranes function as a barrier to separate the cell nucleus from the cytoplasm, but this barrier can be compromised by nuclear membrane ruptures, leading to intermixing of nuclear and cytoplasmic contents. Spontaneous nuclear membrane ruptures ( i.e ., ruptures occurring in the absence of mechanical stress) have been observed in cultured cells, but they are more frequent in the setting of defects or deficiencies in nuclear lamins and when cells are subjected to mechanical stress. Nuclear membrane ruptures in cultured cells have been linked to DNA damage, but the relevance of ruptures to developmental or physiologic processes in vivo has received little attention. Recently, we addressed that issue by examining neuronal migration in the cerebral cortex, a developmental process that subjects the cell nucleus to mechanical stress. In the setting of lamin B1 deficiency, we observed frequent nuclear membrane ruptures in migrating neurons in the developing cerebral cortex and showed that those ruptures are likely the cause of observed DNA damage, neuronal cell death, and profound neuropathology. In this review, we discuss the physiologic relevance of nuclear membrane ruptures, with a focus on migrating neurons in cell culture and in the cerebral cortex of genetically modified mice.

A 59-year-old man with past histories of bronchial asthma and chronic sinusitis underwent transanal resection of anorectal malignant melanoma with general anesthesia. On the third day after surgery, he presented with subacute weakness with right dominant hypoesthesia in the bilateral lower limbs. Tendon reflexes were diminished without pathological reflexes. Blood examination showed increased eosinophils (2,058/μl) and elevated serum immunoglobulin E (675.0 IU/ml). Cerebrospinal fluid examination showed elevated protein (200 mg/dl) without pleocytosis (<5/μl). A nerve conduction study suggested multiple mononeuropathy with motor and axonal dominance in the right tibial, peroneal, and sural nerves. Because of eosinophilia and his past medical history (i.e., bronchial asthma and chronic sinusitis), we initially suspected eosinophilic polyangiitis granulomatosis (EGPA) as the cause of postoperative polyneuropathy. However, his neurological symptoms did not improve despite the decreased eosinophil count after tumor resection, which was inconsistent with EGPA. We biopsied the left sural nerve to exclude EGPA and make a diagnosis. Pathological findings revealed no demyelination, axonal degeneration, or eosinophil infiltration with granuloma formation; however, lymphocyte-dominated inflammation was observed around the epineurial small vessels. Thus, the patient was diagnosed with early onset post-surgical inflammatory neuropathy (PIN) based on his clinical course and the pathological findings. On post-surgery day 48, oral administration of prednisolone (40 mg/day) was started. His neurological symptoms improved quickly and remarkably. Our case suggests that, when multiple mononeuropathy develops early after surgery, PIN should be considered as a differential diagnosis to initiate appropriate treatment based on the pathological condition of neuropathy.

Laryngeal paralysis associated with a generalized polyneuropathy (LPPN) most commonly exists in geriatric dogs from a variety of large and giant breeds. The purpose of this study was to discover the underlying genetic and molecular mechanisms in a younger-onset form of this neurodegenerative disease seen in two closely related giant dog breeds, the Leonberger and Saint Bernard. Neuropathology of an affected dog from each breed showed variable nerve fiber loss and scattered inappropriately thin myelinated fibers. Using across-breed genome-wide association, haplotype analysis, and whole-genome sequencing, we identified a missense variant in the CNTNAP1 gene (c.2810G>A; p.Gly937Glu) in which homozygotes in both studied breeds are affected. CNTNAP1 encodes a contactin-associated protein important for organization of myelinated axons. The herein described likely pathogenic CNTNAP1 variant occurs in unrelated breeds at variable frequencies. Individual homozygous mutant LPPN-affected Labrador retrievers that were on average four years younger than dogs affected by geriatric onset laryngeal paralysis polyneuropathy could be explained by this variant. Pathologic changes in a Labrador retriever nerve biopsy from a homozygous mutant dog were similar to those of the Leonberger and Saint Bernard. The impact of this variant on health in English bulldogs and Irish terriers, two breeds with higher CNTNAP1 variant allele frequencies, remains unclear. Pathogenic variants in CNTNAP1 have previously been reported in human patients with lethal congenital contracture syndrome and hypomyelinating neuropathy, including vocal cord palsy and severe respiratory distress. This is the first report of contactin-associated LPPN in dogs characterized by a deleterious variant that most likely predates modern breed establishment., Competing Interests: Both the University of Minnesota and the University of Bern are offering genotyping tests for polyneuropathy- and leukoencephalomyelopathy-associated variants in their respective laboratories, and proceeds from these tests go toward ongoing canine genetic research. S.G.F is guest editor of this special issue of Genes, but has not in any way been involved in or interacted with the journal’s review process or editorial decision-making. The authors declare that they have no other competing interests.

Objectives: Biallelic mutations in the SLC25A19 gene impair the function of the thiamine mitochondrial carrier, leading to two distinct clinical phenotypes. Homozygosity for the c.530G > C mutation is invariably associated to Amish lethal microcephaly. The second phenotype, reported only in 8 patients homozygous for different non-Amish mutations (c.373G > A, c.580T > C, c.910G > A, c.869T > A, c.576G > C), is characterized by bilateral striatal necrosis and peripheral polyneuropathy. We report a new patient with the non-Amish SLC25A19 phenotype showing compound heterozygosity for the new variant c.673G > A and the known mutation c.373G > A., Case Presentation: The natural history of non-Amish SLC25A19 deficiency is characterized by acute episodes of fever-induced encephalopathy accompanied by isolated lactic acidosis and Leigh-like features at magnetic resonance imaging (MRI). Acute episodes are prevented by high-dose thiamine treatment (600 mg/day). As shown in the new case, both mild clinical signs and basal ganglia involvement can precede the acute encephalopathic onset of the disease, potentially allowing treatment anticipation and prevention of acute brain damage. Peripheral axonal neuropathy, observed in 7 out of 9 patients, is not improved by thiamine therapy. In two early treated patients, however, peripheral neuropathy did not occur even on long-term follow-up, suggesting a potential preventive role of treatment anticipation also at the peripheral level., Conclusions: Non-Amish SLC25A19 deficiency is an extra-rare cause of Leigh syndrome responsive to thiamine treatment. Ex adiuvantibus thiamine treatment is mandatory in any patient with Leigh-like features., (© 2020 Walter de Gruyter GmbH, Berlin/Boston.)

Purpose of Review: Chronic idiopathic axonal polyneuropathy (CIAP), a common neurological condition, is considered to be a benign neurological condition with a small risk of disability. However, many studies have shown a reduced quality of life and a nonnegligible affection of daily activities in patients with CIAP. Here we summarize recent data about CIAP., Recent Findings: We discuss some of the latest articles regarding risk factors, comorbidities, and possible pathogenic factors regarding CIAP. Patients with chronic polyneuropathy have impaired walking capacity, disturbed balance, and an increased risk of falls. Idiopathic polyneuropathy has a negative impact on activities of daily living. Patients with CIAP may develop plantar ulcers and neuropathic arthropathy. Small fiber involvement may occur, and two recent studies indicate that neuropathic pain is present in about two thirds of the CIAP group. Furthermore, patients with CIAP with neuropathic pain have increased fatigue and poorer emotional well being., Summary: Despite the relatively mild motor impairment seen in most patients with CIAP, the condition causes limitations in life with decreased mobility, pain, and affection of basal daily activities. Because the pathogenesis of CIAP in unclear, there is no disease modifying treatment. Further studies regarding pathogenesis, and randomized controlled clinical trials regarding possible treatment options are needed.

Objective: Previous studies in Parkinson's disease (PD) patients have demonstrated a high prevalence of polyneuropathy (PNP) and pronounced alpha-Synuclein pathology in dermal nerve fibers already at early disease stages. The aim of this study was to analyze associations between the prevalence and severity of PNP with nonmotor and motor symptoms in PD patients., Methods: Fifty PD patients were characterized comprehensively for the presence of clinical symptoms (nonmotor and motor), electrophysiologic alterations and - for the first time - using high-resolution ultrasound of peripheral nerves., Results: Sixty-two percent of PD patients showed electrophysiological pathology of PNP. The prevalence of patient-reported PNP symptoms was 86% and was particularly present in patients with longer disease duration, compromised scores of nonmotor and motor symptoms as well as with a negative evaluation of quality of life. Seventy-five percent of patients showed morphologic alterations similar to axonal PNP in high-resolution ultrasound compared to healthy controls., Interpretation: The study demonstrates the high burden of peripheral nervous system disease in Parkinson's disease. It advocates further studies to delineate the underlying pathophysiological mechanisms in order to optimize treatment approaches for PD, including the associated PNP., (© 2020 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)

Aims/introduction: Despite its major clinical impact, distal symmetric polyneuropathy remains frequently undiagnosed and undertreated in clinical practice. We previously reported in the PROTECT Study that 70% of type 2 diabetes patients with distal symmetric polyneuropathy were unaware of having the latter condition., Materials and Methods: In the present follow up after 2.5 ± 0.7 years, 122 and 85 participants with and without type 2 diabetes, respectively, completed questionnaires to obtain information about the further course of disease and its management., Results: At follow up, 49 and 48% of the respondents with type 2 diabetes and without diabetes, respectively, reported that the intensity of paresthesia or numbness in the feet increased, whereas for burning and pain in the feet the corresponding percentages were 56 and 61%. However, 33 and 40% of the respondents with type 2 diabetes and without diabetes, respectively, reporting neuropathic symptoms at follow up did not receive any pharmacotherapy. Pharmacotherapy of neuropathic symptoms at follow up among participants with type 2 diabetes and without diabetes included mainly World Health Organization Step 1 analgesics (17% each; excluding acetylsalicylic acid), pregabalin/gabapentin (20 and 12%), vitamin B complex (13 and 22%), benfotiamine (13 and 2%), opioids (7 and 12%), antidepressants (4 and 5%) and α-lipoic acid (4 and 2%)., Conclusions: These findings point to insufficient care, inadequate treatment adherence or limited efficacy of treatments in patients with polyneuropathy, suggesting that effective measures should be implemented to correct these healthcare deficits., (© 2020 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.)

Introduction: Hereditary transthyretin-mediated (hATTR) amyloidosis is a rare, fatal, multisystem disease leading to deteriorating quality of life (QOL). The impact of patisiran on QOL in patients with hATTR amyloidosis with polyneuropathy from the phase 3 APOLLO study (NCT01960348) is evaluated. Methods: Patients received either patisiran 0.3 mg/kg ( n  = 148) or placebo ( n  = 77) intravenously once every three weeks for 18 months. Multiple measures were used to assess varying aspects of QOL. Results: At 18 months, compared with placebo, patisiran improved Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) score; (least squares [LS] mean difference: -21.1; p  = 1.10 × 10 -10 ; improved across all domains), EuroQoL 5-dimensions 5-levels (LS mean difference: 0.2; p  = 1.4 × 10 -12 ), EuroQoL-visual analog scale (LS mean difference: 9.5; p =.0004), Rasch-built Overall Disability Scale (LS mean difference: 9.0; p  = 4.07 × 10 -16 ) and Composite Autonomic Symptom Score-31(COMPASS-31; LS mean difference: -7.5; p =.0008). Placebo-treated patients experienced rapid QOL deterioration; treatment effects for patisiran were observed as early as 9 months. At 18 months, patisiran improved Norfolk QOL-DN total score and three individual domains as well as COMPASS-31 total scores relative to baseline. Consistent benefits were also observed in the cardiac subpopulation. Conclusion: The benefits of patisiran across all QOL measures and the rapid deterioration observed with placebo, highlight the urgency in early treatment for patients with hATTR amyloidosis with polyneuropathy.

Polyneuropathy is defined as the simultaneous dysfunction of several peripheral nerves. In dogs, a number of breeds are predisposed to a variety of immune-mediated and/or degenerative inherited forms of polyneuropathy, with laryngeal paralysis and/or megaesophagus as important clinical features of many of these conditions. This case series describes degenerative and inflammatory polyneuropathies in 7 young Siberian huskies that were categorized based on clinicopathological characteristics as follows: (1) slowly progressive laryngeal paralysis and megaesophagus caused by primary axonal degeneration with large fiber loss (n = 2); (2) slowly progressive polyneuropathy without megaesophagus or laryngeal paralysis caused by primary axonal degeneration with large fiber loss (n = 2); (3) acute inflammatory demyelinating neuropathy causing sensory, motor and autonomic nerve deficits (n = 2); and (4) ganglioradiculitis (sensory neuronopathy; n = 1). Based on the predominantly young age at onset, slow progression, relatedness of affected dogs, and clinical and pathological similarities with inherited neuropathies reported in other dog breeds, a hereditary basis for the degenerative polyneuropathies in Siberian huskies is suspected. However, 5 different mutations in 3 genes known to cause polyneuropathy in other dog breeds ( NDRG1 , ARHGEF10 , or RAB3GAP1 ) were not detected in the affected Siberian huskies suggesting that more genetic variants remain to be identified. This study highlights the varied underlying lesions of polyneuropathies in young Siberian huskies.

Our aim was to evaluate in a cohort of 125 Italian patients with type 2 diabetes (T2D), who underwent neurological evaluation, the possible differences in the number of mitochondrial DNA copies (mtDNA) comparing positive and negative patients for cardiovascular autonomic neuropathy (CAN) or diabetic peripheral neuropathy (DPN) and comparing them with healthy controls. We also investigated a possible correlation of the number of mtDNA copies with the polymorphism rs3746444 of the MIR499A . T2D patients show a decrease in the number of mtDNA copies compared to healthy controls ( p  = 2 × 10 -10 ). Dividing the T2D subjects by neurological evaluation, we found a significant mtDNA decrease in patients with DPN compared with those without ( p  = 0.02), while no differences were observed between subjects with and without CAN. Furthermore, the homozygous variant genotype for the polymorphism rs3746444 of MIR499A correlates with a decrease in the number of mtDNA copies, particularly in T2D patients ( p  = 0.009). Our data show a decrease in the number of mtDNA copies in subjects with T2D and suggest that this decrease is more evident in patients who develop DPN. Furthermore, the association of the variant allele of MIR499A with the number of mtDNA copies allows us to hypothesize a possible effect of this polymorphism in oxidative stress.

HIV-associated sensory neuropathy is a common neurologic comorbidity of HIV infection and prevails in the post-antiretroviral therapy (ART) era. HIV infection drives pathologic changes in the dorsal root ganglia (DRG) through inflammation, altered metabolism, and neuronal dysfunction. Herein, we characterized specific neuronal populations in an SIV-infected macaque model with or without ART. DRG neuronal populations were identified by neurofilament H-chain 200, I-B 4 isolectin (IB4), or tropomyosin receptor kinase A expression and assessed for cell body diameter, population size, apoptotic markers, and regeneration signaling. IB4 + and tropomyosin receptor kinase A-positive neurons showed a reduced cell body size (atrophy) and decreased population size (cell death) in the DRG of SIV-infected animals compared with uninfected animals. IB4 + nonpeptidergic neurons were less affected in the presence of ART. DRG neurons showed accumulation of cleaved caspase 3 (apoptosis) and nuclear-localized activating transcription factor 3 (regeneration) in SIV infection, which was significantly lower in uninfected animals and SIV-infected animals receiving ART. Nonpeptidergic neurons predominantly colocalized with cleaved caspase 3 staining. Nonpeptidergic and peptidergic neurons colocalized with nuclear-accumulated activating transcription factor 3, showing active regeneration in sensory neurons. These data suggest that nonpeptidergic and peptidergic neurons are susceptible to pathologic changes from SIV infection, and intervention with ART did not fully ameliorate damage to the DRG, specifically to peptidergic neurons., (Copyright © 2020 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Lysophosphatidylserine (lyso-PS), a lysophospholipid derived from phosphatidylserine (PS), has emerged as a potent signaling lipid in mammalian physiology. In vivo , the metabolic serine hydrolases ABHD16A and ABHD12 are major lipases that biosynthesize and degrade lyso-PS, respectively. Of biomedical relevance, deleterious mutations to ABHD12 cause accumulation of lyso-PS in the brain, and this deregulated lyso-PS metabolism leads to the human genetic neurological disorder PHARC (polyneuropathy, hearing loss, ataxia, retinitis pigmentosa, and cataract). While the roles of ABHD16A and ABHD12 in lyso-PS metabolism in the mammalian brain are well established, the anatomical and (sub)cellular localizations of both lipases and the functional cross-talk between them with respect to regulating lyso-PS lipids remain under investigated. Here, using subcellular organelle fractionation, biochemical assays, and immunofluorescence-based high-resolution microscopy, we show that the PS lipase ABHD16A is an endoplasmic reticulum-localized enzyme, an organelle intricately regulating cellular PS levels. In addition, leveraging immunohistochemical analysis using genetic ABHD16A and ABHD12 knockout mice as important controls, we map the anatomical distribution of both of these lipases in tandem in the murine brain and show for the first time the distinct localization of these lipases to different regions and cells of the cerebellum. We complement the aforementioned immunohistochemical studies by quantitatively measuring lyso-PS concentrations in various brain regions using mass spectrometry and find that the cerebellar lyso-PS levels are most affected by deletion of ABHD16A (decreased) or ABHD12 (increased). Taken together, our studies provide new insights into lyso-PS signaling in the cerebellum, the most atrophic brain region in human PHARC subjects.

Background: GFAP (glial fibrillary acidic protein)-IgG is predominantly associated with meningoencephalomyelitis, and neuropathy presentations are rare., Methods: We reviewed clinical, electrodiagnostic and histopathological presentations of GFAP-IgG associated peripheral neuropathy., Results: We identified six cases, five of whom had peripheral neuropathy as the initial presentation. Acute/subacute polyradicluoneuropathy or proximal nerve involvement was a common presentation. Three had demyelinating neuropathies on electrophysiological studies. Nerve biopsies (n = 2) demonstrated T-cell predominant perivascular inflammatory collections, and all patients with clinical follow up responded favorably to immunotherapy., Conclusion: GFAP neuropathy represents a potentially treatable immune-mediated neuropathy and can occur with or without co-existing meningoencephalomyelitis., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Objective: To quantify peripheral nerve lesions in symptomatic and asymptomatic hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PNP) by analyzing the magnetization transfer ratio (MTR) of the sciatic nerve, and to test its potential as a novel biomarker for macromolecular changes., Methods: Twenty-five patients with symptomatic ATTRv-PNP, 30 asymptomatic carriers of the mutant transthyretin gene (mutTTR), and 20 age-/sex-matched healthy controls prospectively underwent magnetization transfer contrast imaging at 3 Tesla. Two axial three-dimensional gradient echo sequences with and without an off-resonance saturation rapid frequency pulse were conducted at the right distal thigh. Sciatic nerve regions of interest were manually drawn on 10 consecutive axial slices in the images without off-resonance saturation, and then transferred to the corresponding slices that were generated by the sequence with the off-resonance saturation pulse. Subsequently, the MTR and cross-sectional area (CSA) of the sciatic nerve were evaluated. Detailed neurologic and electrophysiologic examinations were conducted in all ATTRv-PNP patients and mutTTR-carriers., Results: Sciatic nerve MTR and CSA reliably differentiated between ATTRv-PNP, mutTTR-carriers, and controls. MTR was lower in ATTRv-PNP (26.4 ± 0.7; P < 0.0001) and in mutTTR-carriers (32.6 ± 0.8; P = 0.0005) versus controls (39.4 ± 2.1), and was also lower in ATTRv-PNP versus mutTTR-carriers (P = 0.0009). MTR correlated negatively with the NIS-LL and positively with CMAPs and SNAPs. CSA was higher in ATTRv-PNP (34.3 ± 1.7 mm 3 ) versus mutTTR-carriers (26.0 ± 1.1 mm 3 ; P = 0.0005) and versus controls (20.4 ± 1.2 mm 3 ; P < 0.0001). CSA was also higher in mutTTR-carriers versus controls., Interpretation: MTR is a novel imaging marker that can quantify macromolecular changes in ATTRv-PNP and differentiate between symptomatic ATTRv-PNP and asymptomatic mutTTR-carriers and correlates with electrophysiology., (© 2020 The Authors. Annals of Clinical and Translational Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)

NGLY1 encodes the enzyme N-glycanase that is involved in the degradation of glycoproteins as part of the endoplasmatic reticulum-associated degradation pathway. Variants in this gene have been described to cause a multisystem disease characterized by neuromotor impairment, neuropathy, intellectual disability, and dysmorphic features. Here, we describe four patients with pathogenic variants in NGLY1. As the clinical features and laboratory results of the patients suggested a multisystem mitochondrial disease, a muscle biopsy had been performed. Biochemical analysis in muscle showed a strongly reduced ATP production rate in all patients, while individual OXPHOS enzyme activities varied from normal to reduced. No causative variants in any mitochondrial disease genes were found using mtDNA analysis and whole exome sequencing. In all four patients, variants in NGLY1 were identified, including two unreported variants (c.849T>G (p.(Cys283Trp)) and c.1067A>G (p.(Glu356Gly)). Western blot analysis of N-glycanase in muscle and fibroblasts showed a complete absence of N-glycanase. One patient showed a decreased basal and maximal oxygen consumption rates in fibroblasts. Mitochondrial morphofunction fibroblast analysis showed patient specific differences when compared to control cell lines. In conclusion, variants in NGLY1 affect mitochondrial energy metabolism which in turn might contribute to the clinical disease course., (© 2020 The Authors. Clinical Genetics published by John Wiley & Sons Ltd.)

Whatever the cause of myelin damage of the peripheral nervous system, the initial attack on myelin by a dysimmune process may begin either at the internodal area or in the paranodal and nodal regions. The term "nodo-paranodopathy" was first applied to some "axonal Guillain-Barré syndrome" subtypes, then extended to cases classified as chronic inflammatory demyelinating polyradiculoneuropathy bearing IgG4 antibodies against paranodal axoglial proteins. In these cases, paranodal dissection develops in the absence of macrophage-induced demyelination. In contrast, the mechanisms of demyelination of other dysimmune neuropathies induced by macrophages are unexplained, as no antibodies have been identified in such cases. Electron microscopy of longitudinal sections of nerve biopsies is useful to visualize and authenticate the characteristic lesions of paranodes/nodes. However, it should be borne in mind that identical ultrastructural aspects are seen in other types of polyneuropathies: Genetic, experimental, and in a few polyneuropathies for which there is no obvious etiology. Ultrastructural nerve studies confirm the initial involvement of nodes/paranodes in various types of acquired and genetic neuropathies. For some of them, the antibodies or the proteins involved by mutations are clearly identified such as Caspr-1, Contactin-1, NFasc155, and NFasc186; other unidentified proteins are likely to be involved as well., (© 2019 American Association of Neuropathologists, Inc. All rights reserved.)

Background: Conduction blocks (CB) are the diagnostic hallmark of multifocal motor neuropathy (MMN). Conventional nerve conduction studies cannot detect CB above Erb's point. Our purpose was to compare the performance of the motor evoked potential with triple stimulation technique (MEP-TST) and MRI in the detection of abnormalities of the brachial plexus., Methods: Examinations were performed on 26 patients with MMN (11 definite, 6 probable, 9 possible), of whom 7 had no CB., Results: MEP-TST detected proximal CB in 19/26 patients. Plexus MRI showed T2 hyperintensity in 18/26 patients, with nerve enlargement in 14/18. A combination of both techniques increased the detection rate of brachial plexus abnormalities to 96% of patients (25/26)., Conclusions: MEP-TST and MRI have high sensitivities for detecting brachial plexus abnormalities. A combination of the two techniques increases the detection rate of supportive criteria for the diagnosis of MMN., (© 2019 Wiley Periodicals, Inc.)

Dominant mutations in ATP1A1, encoding the alpha-1 isoform of the Na + /K + -ATPase, have been recently reported to cause an axonal to intermediate type of Charcot-Marie-Tooth disease (ie, CMT2DD) and a syndrome with hypomagnesemia, intractable seizures and severe intellectual disability. Here, we describe the first case of hereditary spastic paraplegia (HSP) caused by a novel de novo (p.L337P) variant in ATP1A1. We provide evidence for the causative role of this variant with functional and homology modeling studies. This finding expands the phenotypic spectrum of the ATP1A1-related disorders, adds a piece to the larger genetic puzzle of HSP, and increases knowledge on the molecular mechanisms underlying inherited axonopathies (ie, CMT and HSP)., (© 2019 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Consistent associations between the severity of neuropathic pain and cutaneous innervation have not been described. We collected demographic and clinical data, McGill Pain Questionnaires (MPQ) and skin biopsies processed for PGP9.5 and CGRP immunohistochemistry from patients with bortezomib-induced peripheral neuropathy (BiPN; n = 22), painful diabetic neuropathy (PDN; n = 16), chronic idiopathic axonal polyneuropathy (CIAP; n = 16) and 17 age-matched healthy volunteers. Duration of neuropathic symptoms was significantly shorter in patients with BiPN in comparison with PDN and CIAP patients. BiPN was characterized by a significant increase in epidermal axonal swellings and upper dermis nerve fiber densities (UDNFD) and a decrease in subepidermal nerve fiber densities (SENFD) of PGP9.5-positive fibers and of PGP9.5 containing structures that did not show CGRP labeling, presumably non-peptidergic fibers. In PDN and CIAP patients, intraepidermal nerve fiber densities (IENFD) and SENFD of PGP9.5-positive and of non-peptidergic fibers were decreased in comparison with healthy volunteers. Significant unadjusted associations between IENFD and SENFD of CGRP-positive, i.e. peptidergic, fibers and the MPQ sensory-discriminative, as well as between UDNFD of PGP9.5-positive fibers and the MPQ evaluative/affective component of neuropathic pain, were found in BiPN and CIAP patients. No significant associations were found in PDN patients. Cutaneous innervation changes in BiPN confirm characteristic features of early, whereas those in CIAP and PDN are in line with late forms of neuropathic pathology. Our results allude to a distinct role for non-peptidergic nociceptors in BiPN and CIAP patients. The lack of significant associations in PDN may be caused by mixed ischemic and purely neuropathic pain pathology., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Background: Chronic autoimmune demyelinating polyneuropathies (CADP) result in impaired sensorimotor function. However, anecdotal clinical observations suggest the development of cognitive deficits during the course of disease., Methods: We tested 16 patients with CADP (11 patients with chronic inflammatory demyelinating polyneuropathy, 4 patients with multifocal motor neuropathy and 1 patient with multifocal acquired demyelinating sensory and motor neuropathy) and 40 healthy controls (HC) with a neuropsychological test battery. Blood-brain-barrier dysfunction (BBBd) in patients was assessed retrospectively by analysing the cerebral spinal fluid (CSF) status at the time the diagnosis of CAPD was established., Results: CADP patients failed on average in 1.7 out of 9 neuropsychological tests (SD ± 1.25, min. 0, max. 5). 50% of the CADP patients failed in at least two neuropsychological tests and 44.3% of the patients failed in at least two different cognitive domains. CADP patients exhibiting BBBd at the time of first diagnosis failed in more neuropsychological tests than patients with intact integrity of the BBB (p < 0.05). When compared directly with the HC group, CADP patients performed worse than HC in tests measuring information processing ability and speed as well as phonemic verbal fluency after adjusting for confounding covariates., Conclusions: Our results suggest that mild to moderate cognitive deficits might be present in patients with CAPD. One possible tentative explanation, albeit strong evidence is still lacking for this pathophysiological mechanism, refers to the effect of autoimmune antibodies entering the CNS via the dysfunctional blood-brain barrier typically seen in some of the CADP patients., Competing Interests: Yavor Yalachkov has been supported by travel grants from Novartis and Sanofi Genzyme, has received an honorarium for active participation in an advisory board by Sanofi Genzyme as well as a speaking honorarium by Roche. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Introduction: Nerve biopsy has been widely used to investigate patients with peripheral neuropathy, and in many centers, it is still a useful diagnostic tool in this setting. In this study, we reviewed the histopathological spectrum of the nerve biopsies performed in our center in a 30-year period and we analyzed their relevance in the clinical setting., Materials and Methods: Retrospective analysis of the retrieved data was done for cases of nerve biopsies performed in our institute between 1988 and 2018. Surgical technique and histopathological analysis were done accordingly to standard protocol., Results: Complete clinical and pathological data were available only for 717 cases. The procedure was generally safe, with only 0.3% superimposed infection. Main pathological results were "unspecific" axonal polyneuropathy (49.8%), vasculitis neuropathy (9.3%), acquired demyelinating neuropathy (8.9%), and Charcot-Marie-Tooth (8.2%). Considering clinical-neurophysiological suspicion of vasculitis, nerve biopsy confirmed the diagnosis in 60.9% of cases., Discussion: In conclusion, for inherited neuropathies, we do not recommend this invasive procedure, but we strongly suggest a genetic test. Conversely, in vasculitic neuropathies or in dysimmune neuropathies not clearly confirmed by neurophysiological examination, nerve biopsy continues to represent a useful and irreplaceable tool.