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Introduction: Autoimmune nodopathy (AN) is a new entity in the field of peripheral neuropathies and is defined by the presence of auto-antibodies against structures of the node of Ranvier combined with specific clinicopathophysiological features and therapy response in affected patients. The target-specific antibodies do not only serve as diagnostic biomarkers but also for treatment evaluation during follow-up. Case report: We report a 66-year-old female patient with various autoimmune diseases, including a history of membranous glomerulonephritis which presented with acute-onset, sensorimotor tetraparesis, cranial nerve involvement, and mild respiratory insufficiency. Under the suspicion of Guillain--Barreé syndrome, she received intravenous immunoglobulins (IVIg) and achieved remission. At 8 months later, she relapsed with now a poor response to IVIg and developed additional features such as severe sensory ataxia, tremor, and neuropathic pain. Anti-contactin-1 IgG2 antibodies were detected, and the diagnosis was reverted to AN. Plasma exchange and rituximab treatment led to a serological remission and corresponding significant clinical improvement, and the therapy was paused. At 2 years after symptom onset, her condition worsened again with sensorimotor symptoms and severe neuropathic pain despite seronegativity for contactin-1. However, serum binding assays to teased nerve fiber staining showed recurring antibody reactivity against paranodal structures. Caspr-1 was identified as a new target antigen via cell-based assay, and high-titer antibodies of the IgG4 subclass were confirmed via ELISA. Hence, a new cycle of plasma exchange and regular rituximab treatment was initiated, with subsequent clinical improvement and serological remission. The serum neurofilament light chain (sNFL) levels were assessed retrospectively and rose and fell together with the antibody titer. Discussion: This case demonstrates that autoimmunity to (para)nodal structures can reoccur especially in patients prone to autoimmune disorders and can switch its target antigen and subclass in the course of disease. The presence of autoantibodies against different targets at the node of Ranvier has direct implications for therapeutic management. We suggest a close follow-up of patients with AN after successful therapy. In case of deterioration despite seronegativity, nonspecific tests such as teased fiber assays and repeated screening for different target antigens should be considered. [ABSTRACT FROM AUTHOR]

A 6-year-old female spayed Podenco-crossbreed dog was presented with an unusual type of focal impaired awareness seizures, including sensory ataxia and postictal rest. Magnetic resonance imaging examination revealed pre- and postcontrast agent T1-weighted bilateral symmetric hyperintensities in the lentiform nuclei and globus pallidus. Repeated cerebrospinal fluid sampling showed lymphocytic pleocytosis. Cerebrospinal fluid immunoglobulin G autoantibodies to myelin basic protein (MBP) were detected by immunofluorescence examination with strong binding to myelinated fiber tracts. The absence of binding to MBP-depleted mouse brains confirmed MBP as an antigenic target. Although the patient had minor seizure episodes every 2 months, and the owners avoided seizure triggers, they refused medical treatment before presenting to the veterinarian. To the best of our knowledge, this is the first description of MBP autoantibody-positive encephalitis in a dog. [ABSTRACT FROM AUTHOR]

Introduction: Ubiquitin C-terminal hydrolase L1 (UCHL1) has been associated with a severe, complex autosomal recessive spastic paraplegia (HSP79) [1] [2] [3] [4]. More recently, UCHL1 loss of function (LoF) variants have been associated to an autosomal dominant disease characterized by late-onset spastic ataxia, neuropathy, and frequent optic atrophy [5]. Methods: Routine clinical care whole-genome (WGS) and exome (ES) sequencing. Results: We present three families with autosomal dominant UCHL1-related disorder. The clinical phenotype mainly associated optic atrophy, mixed cerebellar and sensory ataxia, and possible hearing loss. We delineated two major phenotypes, even within the same family: (1) juvenile severe optic atrophy followed by a later-onset ataxia, or (2) late-onset ataxia with asymptomatic or mild optic atrophy. The families harboured three novel heterozygous variants in UCHL1: two loss of function (p.Lys115AsnfsTer40; c.171_174 + 7del11), and one missense (p.Asp176Asn) involving the catalytic site of the protein and potentially altering the adjacent splice site. Discussion: We confirm the existence of dominantly inherited UCHL1 pathogenic variants. We describe a considerable intrafamilial phenotypic variability, with two main phenotypes. Optic atrophy was consistently present, but with varying degrees of severity. Neither delayed motor or intellectual development, nor dysmorphic features were part of the dominant phenotype in comparison with the autosomal recessive form. The molecular mechanism appears to be haploinsufficiency. UCHL1 monoallelic variants should therefore be considered in any case of early-onset optic atrophy or in late-onset complex ataxic syndrome with asymptomatic optic atrophy. [ABSTRACT FROM AUTHOR]

Background Objectives Methods Results Conclusions Neuroaxonal dystrophy (NAD) is a group of inherited neurodegenerative disorders characterized primarily by the presence of spheroids (swollen axons) throughout the central nervous system. In humans, NAD is heterogeneous, both clinically and genetically. NAD has also been described to naturally occur in large animal models, such as dogs. A newly recognized disorder in Miniature American Shepherd dogs (MAS), consisting of a slowly progressive neurodegenerative syndrome, was diagnosed as NAD via histopathology.To describe the clinical and pathological phenotype together with the identification of the underlying genetic cause.Clinical and postmortem evaluations, together with a genome‐wide association study and autozygosity mapping approach, followed by whole‐genome sequencing.Affected dogs were typically young adults and displayed an abnormal gait characterized by pelvic limb weakness and ataxia. The underlying genetic cause was identified as a 1‐bp (base pair) deletion in RNF170 encoding ring finger protein 170, which perfectly segregates in an autosomal recessive pattern. This deletion is predicted to create a frameshift (XM_038559916.1:c.367delG) and early truncation of the RNF170 protein (XP_038415844.1:(p.Ala123Glnfs*11)). The age of this canine RNF170 variant was estimated at ~30 years, before the reproductive isolation of the MAS breed.RNF170 variants were previously identified in human patients with autosomal recessive spastic paraplegia‐85 (SPG85); this clinical phenotype shows similarities to the dogs described herein. We therefore propose that this novel MAS NAD could serve as an excellent large animal model for equivalent human diseases, particularly since affected dogs demonstrate a relatively long lifespan, which represents an opportunity for therapeutic trials. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

Background & purpose: In this retrospective study, we aimed at defining the clinical, paraclinical and outcome features of acute neurological syndromes associated with anti-GQ1b antibodies. Results: We identified 166 patients with neurological symptoms appearing in less than 1 month and anti-GQ1b antibodies in serum between 2012 and 2022. Half were female (51%), mean age was 50 years (4–90), and the most frequent clinical features were areflexia (80% of patients), distal upper and lower limbs sensory symptoms (78%), ophthalmoplegia (68%), sensory ataxia (67%), limb muscle weakness (45%) and bulbar weakness (45%). Fifty-three patients (32%) presented with complete (21%) and incomplete (11%) Miller Fisher syndrome (MFS), thirty-six (22%) with Guillain–Barre syndrome (GBS), one (0.6%) with Bickerstaff encephalitis (BE), and seventy-three (44%) with mixed MFS, GBS & BE clinical features. Nerve conduction studies were normal in 46% of cases, showed demyelination in 28%, and axonal loss in 23%. Anti-GT1a antibodies were found in 56% of cases, increased cerebrospinal fluid protein content in 24%, and Campylobacter jejuni infection in 7%. Most patients (83%) were treated with intravenous immunoglobulins, and neurological recovery was complete in 69% of cases at 1 year follow-up. One patient died, and 15% of patients relapsed. Age > 70 years, initial Intensive Care Unit (ICU) admission, and absent anti-GQ1b IgG antibodies were predictors of incomplete recovery at 12 months. No predictors of relapse were identified. Conclusion: This study from Western Europe shows acute anti-GQ1b antibody syndrome presents with a large clinical phenotype, a good outcome in 2/3 of cases, and frequent relapses. [ABSTRACT FROM AUTHOR]

Purpose: To present a rare case of neurosyphilis, the tertiary form of syphilitic infection, following adequate but belated treatment and manifesting with a variety of clinical signs and further progression to tabetic neurosyphilis. Known as the "great imitator", neurosyphilis is often misdiagnosed and underestimated. Materials/methods: A 48-year-old male patient was admitted to the Neurology clinic of UMHAT "Dr Georgi Stranski" Pleven, Bulgaria, with progressive neurological deficit including numbness in the lower limbs, imbalance and wide-based gait. The T2W- MRI showed abnormally high longitudinal signals at Th12-L1 level, consistent with transverse myelitis. CSF analysis revealed leucocytic pleocytosis, elevated proteins and normal glucose. The nerve conduction studies confirmed sensory motor polyneuropathy. Results: After treatment with intravenous aqueous crystalline (IV) penicillin, 2 million intravenously every 4 hours for 20 days, the sensory symptoms reduced. The coordination disturbances persisted, but the gate showed moderate improvement. Conclusions: The diagnosis of syphilitic myelitis, known as tabes dorsalis, is always complex, not only because of its rarity but because of its unique clinical presentation with multiple clinical symptoms, mimicking other more common neurological disorders. Though confirmation of the diagnosis needs a lot of laboratory and neuroimaging studies, the option of effective specific treatment is worth all the efforts.

Background and purpose: The aim of this study was to determine the prevalence of anti‐myelin‐associated glycoprotein (MAG) neuropathy and the current status of such patients in Japan. Methods: We conducted a nationwide survey in 2021 using established epidemiological methods. Questionnaires were sent to all neurology and pediatric neurology departments throughout Japan to identify patients with anti‐MAG neuropathy. An initial questionnaire was used to determine the number of patients, with a second one used to collect detailed clinical information. Results: The estimated number of patients with anti‐MAG neuropathy was 353, with a prevalence of 0.28 per 100,000 and an incidence of 0.05 per 100,000. The detailed clinical profiles of 133 patients were available. The median (range) age of onset was 67 (30–87) years, with a prominent peak in the age range 66–70 years, and the male‐to‐female ratio was 3.6. Most patients had distal sensory‐predominant polyneuropathy, and neuropathic pain (50%), or sensory ataxia (42%), while 18% had Waldenström's macroglobulinemia or multiple myeloma. Intravenous immunoglobulin was the most frequently used treatment (65%), but the response rate was <50%, whereas rituximab was given in 32% of patients, and 64% of these showed improvement. At the last visit, 27% of patients could not walk independently. Conclusions: This study on anti‐MAG neuropathy provides updated insights into the epidemiology of this disease, clinical profiles, and treatment approaches in Japan. Rituximab therapy, used for only one‐third of the patients, demonstrated efficacy. During the final visit, a quarter of the patients were unable to walk independently. Further studies are warranted to determine the optimal management of this rare and intractable disorder. [ABSTRACT FROM AUTHOR]

The mutations of the feline leukemia virus subgroup C receptor‐related protein 1 (FLVCR1) cause ataxia with retinitis pigmentosa. Recent studies indicated a large variation in the phenotype of FLVCR1‐associated diseases. In this report, we describe an adult male who manifested first with tremors in his third decade, followed by retinitis pigmentosa, sensory ataxia, and sensory neuropathy in his fourth decade. While retinitis pigmentosa and sensory ataxia are well‐recognized features of FLVCR1‐associated disease, tremor is rarely described. Whole‐exome sequencing revealed novel compound heterozygous pathogenic FLVCR1 variants: c.498 G > A; p.(Trp166*) and c.369 T > G; p.(Phe123Leu). In addition, we have highlighted the ultrastructural abnormalities of the sural biopsy in this patient. [ABSTRACT FROM AUTHOR]

Gait and balance difficulties pose significant clinical challenges in Parkinson's disease (PD). The impairment of physiological mechanisms responsible for maintaining natural orthostatism plays a central role in the pathophysiology of postural instability observed in PD. In addition to the well-known rigidity and abnormalities in muscles and joints, various brain regions involved in the regulation of posture, balance, and gait, such as the basal ganglia, cerebellum, and brainstem regions like the pontine peduncle nucleus, are affected in individuals with PD. The recognition of the cerebellum's role in PD has been increasingly acknowledged. Cortical areas and their connections are associated with freezing of gait, a type of frontal lobe ataxia commonly observed in PD. Furthermore, impairments in the peripheral nervous system, including those caused by levodopatherapy, can contribute to gait impairment and imbalance in PD patients. Consequently, individuals with PD may exhibit frontal ataxia, sensory ataxia, and even cerebellar ataxia as underlying causes of gait disturbances and imbalance, starting from the early stages of the disease. The complex interplay between dysfunctional brain regions, impaired cortical connections, and peripheral nervous system abnormalities contributes to the multifaceted nature of gait and balance difficulties in PD. Understanding the intricate mechanisms is crucial for the development of effective therapeutic approaches targeting these specific deficits in PD. [ABSTRACT FROM AUTHOR]

Aim: X‐linked variants in Filamin A (FLNA) are associated with the Ehlers‐Danlos‐syndrome‐variant form of periventricular heterotopia, and autosomal dominant variants in ubiquitin C‐terminal hydrolase L1 (UCHL1) are associated with a late‐onset spastic ataxia, peripheral neuropathy and optic atrophy. Here we present a rare case involving both a novel heterozygous whole‐gene deletion of UCHL1 and a heterozygous frameshift variant in the FLNA gene resulting in a complex phenotype. Methods: A 67‐year‐old female with a confirmed pathogenic variant in the FLNA gene, resulting in an enlarged aorta and joint pains, presented with a 4‐year history of severe sensory ataxia, upper motor neuron signs, eye movement abnormalities and severe sensory loss. Results: Neurophysiology including Somatosensory‐evoked potentials confirmed the sensory loss as predominantly preganglionic with denervation. Genetic testing revealed a digenic cause of her complex presentation, confirming a pathogenic frameshift variant in the FLNA gene and a heterozygous loss of function deletion in the UCHL1 gene. Conclusions: To the best of our knowledge, this is the first case with concomitant pathogenic variants in the FLNA and UCHL1 genes which explain the complex phenotype. The severe preganglionic sensory loss is also a rare finding and expands the phenotype of UCHL1 variants. [ABSTRACT FROM AUTHOR]

Cerebellar ataxias are a wide heterogeneous group of movement disorders. Within this broad umbrella of diseases, there are both genetics and sporadic forms. The clinical presentation of these conditions can exhibit a diverse range of symptoms across different age groups, spanning from pure cerebellar manifestations to sensory ataxia and multisystemic diseases. Over the last few decades, advancements in our understanding of genetics and molecular pathophysiology related to both dominant and recessive ataxias have propelled the field forward, paving the way for innovative therapeutic strategies aimed at preventing and arresting the progression of these diseases. Nevertheless, the rarity of certain forms of ataxia continues to pose challenges, leading to limited insights into the etiology of the disease and the identification of target pathways. Additionally, the lack of suitable models hampers efforts to comprehensively understand the molecular foundations of disease's pathophysiology and test novel therapeutic interventions. In the following review, we describe the epidemiology, symptomatology, and pathological progression of hereditary ataxia, including both the prevalent and less common forms of these diseases. Furthermore, we illustrate the diverse molecular pathways and therapeutic approaches currently undergoing investigation in both pre-clinical studies and clinical trials. Finally, we address the existing and anticipated challenges within this field, encompassing both basic research and clinical endeavors. [ABSTRACT FROM AUTHOR]

Introduction: Guillain-Barré syndrome (GBS) is a rare disease that affects almost 0.8-1.9 cases per 100,000 people worldwide every year. This is the most prevalent cause of subacute flaccid paralyzing illness today. It is a subacute inflammatory demyelinating polyradiculoneuropathy; the typical scenario involves ascending symmetrical flaccid paralysis, but in some circumstances, sensory, autonomic, and cranial neuropathy may also be involved. Several vaccines have been found to have complications since the previous century. Numerous case reports of GBS in the literature have been reported following COVID-19 vaccines in recent times. Objective: This study aimed to conduct a comprehensive examination of GBS cases that have been reported after COVID-19 vaccines; to analyze the descriptive statistical analysis of data gathered regarding clinical, laboratory, electrophysiological, and radiological characteristics; to discuss, based on the available evidence, whether the disease has a preference for a particular vaccine type; and to speculate on the potential pathogenesis. Methodology: This review has been carried out by recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Result: Reviewing 60 case reports illustrated that most of them are from the USA (18.1%) and the majority of affected individuals were males (60%). The results favored the association between vector-based SARS-CoV-2 vaccine, particularly AstraZeneca vaccine, and the GBS. The mean of symptoms onset is 11.4 days. The results of diagnostic tests such as LP are consistent mostly with albumin-cytological dissociation (81.81%), where brain and spine MRI was unremarkable in 59.52%. Regarding electrodiagnostic tests, AIDP is the most common variant (61.81%). The management was not consistent among the case reports. However, IVIG is the most frequent way of treating these patients (68.33%). The functional outcome was documented in 47 patients; 65% improved with medical management. Conclusion: This study aimed to conduct a systematic review of reported cases of GBS following COVID-19 vaccines and descriptive statistical analysis of collected data on clinical, laboratory, electrophysiological, and radiological features, to discuss, based on available results, whether the disease has a predilection to a specific vaccine type and to speculate the potential pathogenesis. [ABSTRACT FROM AUTHOR]

Background: Previous studies suggest a relationship between central nervous system inflammatory demyelinating diseases and anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis. Also, the overlap between anti-NMDAR encephalitis and multiple sclerosis (MS) has been reported. However, the pathogenesis and clinical characteristics are still obscure. Case presentation: A 33-year-old woman presented with diplopia and sensory ataxia at the onset. The cerebrospinal fluid (CSF) anti-NMDAR antibodies were positive (1:3.2), and nuclear magnetic resonance imaging (MRI) showed bilateral centrum ovale and lateral ventricle demyelinating lesions. Therefore, she was diagnosed with anti-NMDAR encephalitis. After administering intravenous immunoglobulin and oral prednisone, her lesions disappeared, and symptoms were relieved. The condition was maintained with a low dose of prednisone, but her lesions reappeared on MRI. Consequently, immunomodulatory therapy of mycophenolate mofetil was initiated. However, she developed dysarthria and right limb ataxia after 10 months with a positive CSF anti-NMDAR antibody (1:1) and positive oligoclonal band. The MRI showed symmetrical multiple demyelinating lesions. Considering the MS diagnosis, her neurological dysfunction again improved significantly after intravenous methylprednisolone. Unfortunately, her symptoms aggravated for the second time when teriflunomide was started. Finally, her condition was controlled again with oral prednisone. Conclusions: Consistent with previous cases of overlapping anti-NMDAR encephalitis and MS, patients often show atypical symptoms on MRIs and immunological tests. The overlap cannot be arbitrarily treated because of the recurrence of previous diseases. Long-term follow-up, dynamic antibody monitoring, and MRI examination are crucial for these patients. The special dependency of the patient on glucocorticoids in this study has been rarely reported, which may guide the treatment of insensitivity to disease-modifying therapy in recurrent overlapping anti-NMDAR encephalitis and MS. [ABSTRACT FROM AUTHOR]

IntroductionGuillain–Barré syndrome (GBS) is a rare disease that affects almost 0.8–1.9 cases per 100,000 people worldwide every year. This is the most prevalent cause of subacute flaccid paralyzing illness today. It is a subacute inflammatory demyelinating polyradiculoneuropathy; the typical scenario involves ascending symmetrical flaccid paralysis, but in some circumstances, sensory, autonomic, and cranial neuropathy may also be involved. Several vaccines have been found to have complications since the previous century. Numerous case reports of GBS in the literature have been reported following COVID-19 vaccines in recent times.ObjectiveThis study aimed to conduct a comprehensive examination of GBS cases that have been reported after COVID-19 vaccines; to analyze the descriptive statistical analysis of data gathered regarding clinical, laboratory, electrophysiological, and radiological characteristics; to discuss, based on the available evidence, whether the disease has a preference for a particular vaccine type; and to speculate on the potential pathogenesis.MethodologyThis review has been carried out by recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.ResultReviewing 60 case reports illustrated that most of them are from the USA (18.1%) and the majority of affected individuals were males (60%). The results favored the association between vector-based SARS-CoV-2 vaccine, particularly AstraZeneca vaccine, and the GBS. The mean of symptoms onset is 11.4 days. The results of diagnostic tests such as LP are consistent mostly with albumin-cytological dissociation (81.81%), where brain and spine MRI was unremarkable in 59.52%. Regarding electrodiagnostic tests, AIDP is the most common variant (61.81%). The management was not consistent among the case reports. However, IVIG is the most frequent way of treating these patients (68.33%). The functional outcome was documented in 47 patients; 65% improved with medical management.ConclusionThis study aimed to conduct a systematic review of reported cases of GBS following COVID-19 vaccines and descriptive statistical analysis of collected data on clinical, laboratory, electrophysiological, and radiological features, to discuss, based on available results, whether the disease has a predilection to a specific vaccine type and to speculate the potential pathogenesis.

Background: Gonadal dysgenesis with minifascicular neuropathy (GDMN) is a rare autosomal recessive condition associated with biallelic DHH pathogenic variants. In 46, XY individuals, this disorder is characterized by an association of minifascicular neuropathy (MFN) and gonadal dysgenesis, while in 46, XX subjects only the neuropathic phenotype is present. Very few patients with GDMN have been reported so far. We describe four patients with MFN due to a novel DHH likely pathogenic homozygous variant and the results of nerve ultrasound assessment. Methods: This retrospective observational study included 4 individuals from 2 unrelated Brazilian families evaluated for severe peripheral neuropathy. Genetic diagnosis was performed with a peripheral neuropathy next-generation sequencing (NGS) panel based on whole exome sequencing focused analysis that included a control SRY probe to confirm genetic sex. Clinical characterization, nerve conduction velocity studies, and high-resolution ultrasound nerve evaluation were performed in all subjects. Results: Molecular analysis disclosed in all subjects the homozygous DHH variant p.(Leu335Pro). Patients had a striking phenotype, with marked trophic changes of extremities, sensory ataxia, and distal anesthesia due to a sensory-motor demyelinating polyneuropathy. One 46, XY phenotypically female individual had gonadal dysgenesis. High-resolution nerve ultrasound showed typical minifascicular formation and increased nerve area in at least one of the nerves assessed in all patients. Conclusion: Gonadal dysgenesis with minifascicular neuropathy is a severe autosomal recessive neuropathy characterized by trophic alterations in limbs, sensory ataxia, and distal anesthesia. Nerve ultrasound studies are very suggestive of this condition and may help to avoid invasive nerve biopsies. [ABSTRACT FROM AUTHOR]

Gait analysis could be used in animal models as an indicator of sensory ataxia due to chemotherapy-induced peripheral neurotoxicity (CIPN). Over the years, gait analysis in in vivo studies has evolved from simple observations carried out by a trained operator to computerised systems with machine learning that allow the quantification of any variable of interest and the establishment of algorithms for behavioural classification. However, there is not a consensus on gait analysis use in CIPN animal models; therefore, we carried out a systematic review. Of 987 potentially relevant studies, 14 were included, in which different methods were analysed (observation, footprint and CatWalk™). We presented the state-of-the-art of possible approaches to analyse sensory ataxia in rodent models, addressing advantages and disadvantages of different methods available. Semi-automated methods may be of interest when preventive or therapeutic strategies are evaluated, also considering their methodological simplicity and automaticity; up to now, only CatWalk™ analysis has been tested. Future studies should expect that CIPN-affected animals tend to reduce hind paw support due to pain, allodynia or loss of sensation, and an increase in swing phase could or should be observed. Few available studies documented these impairments at the last time point, and only appeared later on respect to other earlier signs of CIPN (such as altered neurophysiological findings). For that reason, gait impairment could be interpreted as late repercussions of loss of sensory.

Background: Various neurological disorders have been reported after vaccination against coronavirus disease 2019, one of which is Guillain–Barré Syndrome (GBS). Case Presentation: We report a case of a 73‐year‐old woman who developed GBS and extra‐GBS manifestations 19 days after the second dose of BNT162b2 mRNA vaccine. She presented lower limb predominant muscle weakness and loss of tendon reflexes. Nerve conduction study showed acute motor and sensory axonal neuropathy. In addition, she developed notable deep sensory ataxia, and showed positive pathological reflex, gaze‐evoked nystagmus and altered consciousness, which suggested brainstem involvement. Conclusions: This is the first coronavirus disease 2019 vaccine‐related GBS complicated with such central nervous system manifestations. [ABSTRACT FROM AUTHOR]

Background: Periaxins (encoded by PRX) play an important role in the stabilization of peripheral nerve myelin. Mutations in PRX can lead to Charcot-Marie-Tooth disease type 4F (CMT4F). Methods: In this study, we screened for PRX mutations using next-generation sequencing and whole-exome sequencing in a large Chinese CMT cohort consisting of 465 unrelated index patients and 650 healthy controls. Sanger sequencing was used for the validation of all identified variants. We also reviewed all previously reported PRX-related CMT cases and summarized the clinical manifestations and genetic features of PRX-related CMTs. Results: The hit rate for biallelic PRX variants in our cohort of Chinese CMT patients was 0.43% (2/465). One patient carried a previously unreported splice-site mutation (c.25_27 + 9del) compound heterozygous with a known nonsense variant. Compiling data on CMT4F cases and PRX variants from the medical literature confirmed that early-onset (95.2%), distal amyotrophy or weakness (94.0%), feet deformity (75.0%), sensory impairment or sensory ataxia (65.5%), delayed motor milestones (60.7%), and spinal deformity (59.5%) are typical features for CMT4F. Less frequent features were auditory impairments, respiratory symptoms, late onset, dysarthria or hoarseness, ophthalmic problems, and central nervous systeminvolvement. The two cases with biallelicmissensemutations have later onset age than those with nonsense or frameshiftmutations. We did not note clear correlations between the type and site of mutations and clinical severity or distinct constellations of symptoms. Conclusion: Consistent with observations in other countries and ethnic groups, PRX-related CMT is rare in China. The clinical spectrum is wider than previously anticipated. [ABSTRACT FROM AUTHOR]

Introduction. Stroke in the posterior circulation accounts for 20-30% of ischemic strokes (Frid et al., 2019). The medial medullary stroke accounts for less than 1%. It is caused by a lesion in the vertebral artery or its branches, or the anterior spinal artery (Ropper, Samuels, Klein J, & Prasad, 2019). Prognosis depends on the age of the patient and the severity of the motor deficit on admission (Kim & Han, 2019). A bilateral medial medullary infarct is thus very rare. Methodology. We therefore present a case series of three patients in a tertiary hospital in the Philippines and describe their clinicodemographic profile, clinical presentation, imaging and ancillary diagnostic characteristics and outcome. Age range was from 35 to 64 years old. All three presented with dizziness and varying combinations of cranial nerve deficits, motor, sensory ataxia and cerebellar signs. Imaging modalities used are Magnetic Resonance Imaging (MRI) with time of flight (TOF) and computed tomography angiography (CTA). One had a left vertebral artery (VA) occlusion extending into the proximal basilar artery (BA). Another had a nonvisualized right VA and bilateral posterior inferior cerebellar artery (PICA). The last case had an unremarkable vessel study. Treatment strategies include dual antiplatelet therapy (DAPT) with Aspirin and Cilostazol (2 of 3), and Enoxaparin plus Aspirin. One received intravenous thrombolysis with Alteplase prior to the DAPT. None were intubated and all were home discharged. Conclusion. We have shown that a bilateral medial medullary stroke can present with minimal disability and a good outcome. [ABSTRACT FROM AUTHOR]

Objective: Nodal/paranodal autoantibodies identified a group of peripheral neuropathies independent from chronic inflammatory demyelinating polyneuropathy (CIDP). However, nodopathy with antibody against neurofascin 186 (NF186) was rarely reported. We presented a cohort of patients with anti‐NF186 antibody and described the clinical profile of them. Methods: In this retrospective study, 195 patients diagnosed with CIDP and immune mediated idiopathic neuropathies were enrolled. Cell‐based assay was used to screen anti‐NF186 and anti‐NF155 antibodies in serum samples. Teased‐fiber immunofluorescence were used as a confirmatory assay. Clinical data of seropositive patients were collected and analyzed. Results: Among the patients with anti‐NF186 antibody, seven patients (58.3%) presented acute or subacute disorder onset. Four patients (33.3%) were found to have asymmetric weakness or numbness. Distal weakness and/or numbness was the core feature. Sensory ataxia, tremor and central nervous system demyelination were rarely observed. Nerve conduction studies revealed predominant demyelinating with/without axonal loss. Brachial plexus MRI was normal in the majority of patients (6/7, 85.7%). Five patients (5/9, 55.6%) showed response to intravenous immunoglobulin. Eight patients (8/10, 80.0%) improved after corticosteroids. All patients (3/3,100%) responded to rituximab. Interpretation: In the study, we depicted the clinical profile of nodopathy with anti‐NF186 antibody. The diversity of clinical features, electrophysiology results and pathological findings was specific in nodopathy with anti‐NF186 antibody. Screening of autoantibody against NF186 in acute‐onset neuropathy is recommended. [ABSTRACT FROM AUTHOR]

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Oxidative stress is associated with cardiovascular and neurodegenerative diseases. Here we report studies of neurovascular oxidative stress in chemogenetic transgenic mouse lines expressing yeast D-amino acid oxidase (DAAO) in neurons and vascular endothelium. When these transgenic mice are fed D-amino acids, DAAO generates hydrogen peroxide in target tissues. DAAO-TGCdh5 transgenic mice express DAAO under control of the putatively endothelial-specific Cdh5 promoter. When we provide these mice with D-alanine, they rapidly develop sensory ataxia caused by oxidative stress and mitochondrial dysfunction in neurons within dorsal root ganglia and nodose ganglia innervating the heart. DAAO-TGCdh5 mice also develop cardiac hypertrophy after chronic chemogenetic oxidative stress. This combination of ataxia, mitochondrial dysfunction, and cardiac hypertrophy is similar to findings in patients with Friedreich's ataxia. Our observations indicate that neurovascular oxidative stress is sufficient to cause sensory ataxia and cardiac hypertrophy. Studies of DAAO-TGCdh5 mice could provide mechanistic insights into Friedreich's ataxia. Oxidative stress is associated with cardiovascular and neurodegenerative diseases. Here the authors show studies of transgenic chemogenetic mouse lines that develop sensory ataxia and cardiac hypertrophy caused by neurovascular oxidative stress. [ABSTRACT FROM AUTHOR]

Objective: To investigate the frequency of serum autoantibodies targeting contactin‐associated protein 1 (Caspr1) and its complexes with other paranode antigens, contactin‐1 (CNTN1) and neurofascin 155 (NF155), in Japanese patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Methods: Sera from 26 CIDP patients, 35 patients with Guillain–Barré syndrome, and 31 healthy individuals participated. Paranodal immunoglobulin G antibodies were quantified using enzyme‐linked immunosorbent assays with commercially available recombinant proteins as antigens. Results: Anti‐Caspr1 antibodies were present in one participant (case 1, 3.8%) of CIDP, and negative in all Guillain–Barré syndrome patients and healthy participant. Case 1 was a man who developed subacute distal limb‐predominant muscle weakness and sensory ataxia with postural hand tremor at 69 years‐of‐age, and therapeutic benefit of intravenous immunoglobulin and oral steroids was inadequate. The detected anti‐Caspr1 antibodies predominantly belonged to the immunoglobulin G4 subclass, and the addition of CNTN1 to Caspr1 as an antigen increased antibody reactivity, although the increase was just 20–30% at most. The presence of autoantibodies against paranode protein complexes, including Caspr1/CNTN1, Caspr1/NF155 and Caspr1/CNTN1/NF155, was confirmed in several CIDP patients, although they also had anti‐Caspr1 or anti‐NF155 antibodies; thus, in our cohort, there were no patients with autoantibodies that specifically recognized paranode protein complexes. Conclusions: This is the first confirmed Japanese case of anti‐Caspr1 antibody‐positive CIDP with a clinical signature similar to that of patients of Western origin. Our preliminary study did not identify the presence of specific antibodies against the paranode protein complexes, and the primary target antigen is likely Caspr1. [ABSTRACT FROM AUTHOR]

Spinocerebellar ataxia type 3 (SCA3) is a form of autosomal dominant cerebellar ataxia with a wide range of clinical manifestations, including ataxia and pyramidal and extrapyramidal signs. A few SCA3 patients have been noticed to be predisposed to the development of inclusion body myositis. It is still unknown whether muscle can be primarily involved in the pathogenesis of SCA3. This study reported an SCA3 family in which the index patient initially presented with parkinsonism, sensory ataxia, and distal myopathy but the absence of cerebellar and pyramidal symptoms. The clinical and electrophysiological studies implied a possible combination of distal myopathy and sensory–motor neuropathy or neuronopathy. MRI muscle showed selective fat infiltration and absence of denervated edema‐like changes, indicating the distal muscle weakness had a myopathic origin. Muscle pathology showed the myopathic involvement, besides neurogenic involvement, characterized by chronic myopathic changes with multiple autophagic vacuoles. Genetic screening revealed expanded CAG of 61 repeats in the ATXN3 gene, which showed co‐segregation in the family. Besides the neurogenic origin, the myopathic origin may be partly attributed to the limb weakness of SCA3 patients, which expands the spectrum of the clinical manifestation of SCA3. [ABSTRACT FROM AUTHOR]

Introduction: Ataxia is one the common adverse drug effect caused by Antiepileptic Drugs (AEDs). It can result from either single therapeutic dose of a particular drug, prolonged use of same drug or acute poisoning. Aim: To determine the disease burden and clinical profile of patients who are on AEDs and develop ataxia. Materials and Methods: This was a longitudinal observational study, carried out at Mahatma Gandhi Medical College and Research Institute, Puducherry, from January 2016 to March 2022. The clinical characteristics of patients who presented with ataxia on AEDs and with no previous history of ataxia were documented. Based on the time of onset of ataxia patients were divided into 3 groups: Group A- Ataxia developed within 24 hours of onset of drug intake; Group B- Ataxia developed within 24 to 72 hours from prescription of drug; Group C- Ataxia developed after 72 hours from the time of drug administration. Patients were further classified into those having sensory ataxia and cerebellar ataxia. Based on the time of clinical resolution patients were classified into 3 sub-groups: Group 1- Clinical resolution within 72 hours; Group 2- Clinical resolution in 72 to 144 hours; and Group 3- Clinical resolution after 144 hours. Data was collected systematically and results were statistically analysed using Microsoft Excel spreadsheet software program. Results: Out of the total number of epileptic patients (1600) on AEDs, 34 patients developed ataxia. Of these 34 patients, 15 (44.11%) were on Phenytoin, 12 (35.29%) were on Carbamazepine, 3 (8.82%) were on Gabapentin, 2 (5.88%) were on Zonisamide, and 2 (5.88%) were on Lamotrigine. Dose of these drugs were modified within 1 day, after 1 and 3 weeks and after 1 month in 9 (26.47%), 7 (20.58%), 12 (35.29%), and 4 (11.76%) patients, respectively. Two patients had presented with acute poisoning. Half the 50% (n=17) patients had symptoms of sensory ataxia and remaining half had symptoms of cerebellar ataxia. Conclusion: Ataxia secondary to AEDs is seen with both the older and newer drugs. Awareness of the possibility of AEDs induced ataxia can help in early diagnosis and its management. [ABSTRACT FROM AUTHOR]

Background: Subacute combined degeneration of the spinal cord (SCD) is mainly caused by deficiency of Vitamin B12 and characterized by deep hypoesthesia, sensory ataxia and spasmodic paralysis of lower limbs. SCD often accompanies with megaloblastic anemia. Psychiatric symptoms could be the initial manifestations of SCD by lack of Vitamin B12, but are rarely considered secondary to physical discomfort and psychological factors in SCD. Additionally, treatment experience for psychiatric symptoms in SCD remains little reported. Case report: We presented a case of a 37-year-old female who complained of being persecuted and controlled for one week and thus was admitted to the psychiatry department. Before that, she had went through persistent paresthesia and numbness of her lower extremities for two-month. Low Vitamin B12 level and hemoglobin concentration, neurologic symptoms and bone marrow smear results supported the clinical diagnosis of SCD and megaloblastic anemia. With supplementation of Vitamin B12 and blood transfusion and short-term prescription of antipsychotics and antidepressants, physical symptoms were improved and psychological symptoms disappeared within 2 weeks. Conclusions: Psychiatric symptoms of SCD could be generated from lack of Vitamin B12, anemia and neurologic symptoms, where short-term use of antipsychotics and antidepressants may be effective. [ABSTRACT FROM AUTHOR]

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19), which not only produces respiratory symptoms but is known to involve almost every system, and its neuroinvasive properties have been well demonstrated throughout the pandemic. Also, to combat the pandemic, there was rapid development and induction of various vaccination drives, following which many adverse events following immunization (AEFIs) have been reported, which include neurological complications as well. Method: We present a series of three cases, post vaccination, with and without a history of COVID illness that showed remarkably similar findings on magnetic resonance imaging (MRI). Result: A 38-year-old male presented with complaints of weakness of the bilateral lower limbs with sensory loss and bladder disturbance a day after receiving his first dose of ChadOx1 nCoV-19 (COVISHIELD) vaccine. A 50-year-old male with hypothyroidism characterized by autoimmune thyroiditis and impaired glucose tolerance experienced difficulty in walking 11.5 weeks after being administered with COVID vaccine (COVAXIN). A 38-year-old male presented with subacute onset progressive symmetric quadriparesis 2 months after their first dose of a COVID vaccine. The patient also had sensory ataxia, and his vibration sensation was impaired below C7. All three patients had typical pattern of involvement of the brain and spine on MRI with signal changes in bilateral corticospinal tracts, trigeminal tracts in the brain, and both lateral and posterior columns in the spine. Conclusion: This pattern of brain and spine involvement on MRI is a novel finding and is likely a result of post-vaccination/post-COVID immune-mediated demyelination. [ABSTRACT FROM AUTHOR]

Pathogenic variants in the POLG gene, encoding the mitochondrial DNA (mtDNA) gamma-polymerase, can cause early-onset mtDNA depletion syndromes, such as Alpers syndrome, or later-onset disorders characterized by the presence of multiple mtDNA deletions (MMD), which may encompass autosomal dominant or recessive progressive external ophthalmoplegia (PEO), neuropathy, ataxia, epilepsy, or parkinsonism, among others. We report on the clinical, pathological, and genetic characteristics of 27 patients with POLG-related disorders. Fourteen patients (52%) were female. 67% were adult-onset cases, with a mean age at symptom onset of 34 years (range: 0-67). The most common findings were ophthalmoplegia (80%), ptosis (77%), muscle weakness (54%), lower limb proprioceptive abnormalities (50%), and sensory ataxia (42%). Other relevant ones were tremor (26%), hearing loss (15%), and seizures (7%). SANDO was observed in 26%, pure PEO in 15%, PEO-plus in 11%, and a MNGIE-like phenotype in 4%. The mean CK level was 394 U/L (83-1500). Electrophysiological testing (21/27) revealed sensory axonal polyneuropathy in 33%, sensorimotor axonal neuropathy in 24%, and myopathic changes in 29%. Brain MRI (16 patients) showed normal results in 38%, cerebellar atrophy in 38%, brain atrophy in 31%, and leukoencephalopathy in 13%. Relevant cardiologic involvement was seen in 7%. Muscle biopsy (19 patients) showed histological mitochondrial abnormalities in 82% (i.e., ragged-red fibers and COX-negative fibers). Respiratory chain complexes activities were normal in 88%, and MMD were detected in 93% of them. Nineteen POLG pathogenic variants were identified, with the most frequent alleles being the c.[752C>T;1760C>T] and the c.1399G>A, (33% and 19% of patients, respectively). Inheritance pattern was dominant in 30% and recessive in 65% of cases. A high index of suspicion is needed for diagnosis due to clinical heterogeneity. The presence of MMD should prompt testing for POLG causative variants. [ABSTRACT FROM AUTHOR]

The Romberg test, undoubtedly a classical and well-established method in physical neurological assessment of patients with sensory ataxia, has long been suspected to be prone to several limitations. Here, we quantified upright stance before and after visual deprivation in a selected cohort of patients with pure sensory neuropathy. Static balance was assessed in sensory neuropathy patients during quiet stance on a force platform under different visual and proprioceptive feedback conditions. Sural nerve neurography was employed to evaluate the severity of peripheral neuropathy. Conventional and advanced postural sway metrics were investigated to draw a quantitative analogy to the clinical Romberg test. Posturographic analyses showed that patients displayed Romberg and vestibular Romberg quotient values around 2, indicating an approximately twofold increase in body sway in the absence of vision. However, the diagnostic discrimination ability between patients and controls was only modest. Even less impactful were the diagnostic contributions of frequency domain and non-linear sway analyses. This was primarily attributed to the heightened body sway exhibited by patients with sensory neuropathy under 'eyes open' conditions, diminishing the contrast with the 'eyes closed' condition as assessed in the classical Romberg test. We conclude that the Romberg test, even in its quantitative form with the aid of an apparatus, had an unsatisfactory classification value in terms of distinguishing patients from healthy controls. Instead, it should be interpreted within the comprehensive context of the broader neurological examination and the electrodiagnosis of peripheral nerve function. [ABSTRACT FROM AUTHOR]

Objective: To report a case of autoimmune nodopathy (AN) with concurrent serum and CSF immunoglobulin (Ig)G4 anti-neurofascin 155 (NF155) and anti-GD1b antibodies. Objective: To report a case of autoimmune nodopathy (AN) with concurrent serum and CSF immunoglobulin (Ig)G4 anti-neurofascin 155 (NF155) and anti-GD1b antibodies. Results: NCS revealed a diffuse demyelinating neuropathy in the peripheral nerve with motor and sensory involvement. MRI of the cervical and lumbar plexus showed diffuse enlargement. IgG4 anti-NF155 antibodies in both serum and CSF and IgG anti-GD1b antibodies in serum were positive. After treatment with IVIg, rituximab, and plasma exchange, the titer of the patient's anti-NF155 antibodies decreased, but symptoms did not significantly improve. Discussion: This patient presented a typical clinical feature of AN with serum and CSF anti-NF155 antibodies and serum anti-GD1b antibodies coexistent but poor response to IVIg, rituximab and plasma exchange. Early detection of antibodies may be helpful in both diagnosis and therapy of the disease. And prospective studies are necessary to demonstrate the potential role of anti-NF155 antibodies in CSF and help further understand this complex and heterogeneous disease. [ABSTRACT FROM AUTHOR]

Background: Autoimmune Syndrome Induced by Adjuvants (ASIA) is a concept introduced by Shoenfeld to group various disease entities believed to be triggered by an infection, silicone exposure or other external stimuli. A causal link between the use of silicone and the development of autoimmune diseases and lymphoma has been suggested in the past. Sjögren's Syndrome (SS) is one of the autoimmune diseases that has been postulated as an example of ASIA syndrome. Although typically characterized by sicca, SS can manifest as a ganglionopathy as the primary presenting symptom. To our knowledge, this is the first case report in which a ganglionopathy unveiled an underlying SS in the context of a possible ASIA syndrome.Case Presentation: We describe a case of a 44-year-old woman who developed rapidly progressive sensory loss in the 4 limbs with a walking impairment due to the severe sensory ataxia. After extensive work-up, she was diagnosed with a ganglionopathy as the first symptom of SS, and the concurrent diagnosis of a bilateral breast implant leakage with severe inflammation due to silicone bleeding. After surgical removal of the prostheses and initiation of immunosuppressive therapy, stabilization of symptoms was achieved.Conclusion: This case report brings to attention the possibility of a sensory ganglionopathy as first and isolated symptom of SS. The occurrence of SS in the setting of ASIA stir up the discussion about the safety of silicone breast implants. [ABSTRACT FROM AUTHOR]

ObjectiveTo report a case of autoimmune nodopathy (AN) with concurrent serum and CSF immunoglobulin (Ig)G4 anti-neurofascin 155 (NF155) and anti-GD1b antibodies.MethodsA 20-year-old male presented distal weakness of the 4 limbs, hypoesthesia, absent tendon reflexes and sensory ataxia. Nerve conduction studies (NCS), MRI, and autoantibody tests were performed.ResultsNCS revealed a diffuse demyelinating neuropathy in the peripheral nerve with motor and sensory involvement. MRI of the cervical and lumbar plexus showed diffuse enlargement. IgG4 anti-NF155 antibodies in both serum and CSF and IgG anti-GD1b antibodies in serum were positive. After treatment with IVIg, rituximab, and plasma exchange, the titer of the patient’s anti-NF155 antibodies decreased, but symptoms did not significantly improve.DiscussionThis patient presented a typical clinical feature of AN with serum and CSF anti-NF155 antibodies and serum anti-GD1b antibodies coexistent but poor response to IVIg, rituximab and plasma exchange. Early detection of antibodies may be helpful in both diagnosis and therapy of the disease. And prospective studies are necessary to demonstrate the potential role of anti-NF155 antibodies in CSF and help further understand this complex and heterogeneous disease.

Autoimmune nodopathy (AN) is a group of peripheral neuropathies caused by antibodies targeting the nodes of Ranvier or paranodes. It typically presents with sensory ataxia, distal limb weakness, and tremor, and often has a subacute onset, with limited response to immunoglobulin or corticosteroids. We report a case of anti-contactin-1 neuropathy initially manifesting as isolated superior oblique palsy, aiming to broaden the clinical spectrum of the disease. A 68-year-old male with well-controlled diabetes, hypertension, and hyperlipidemia developed acute binocular vertical diplopia, progressing over two months to include distal paresthesia, sensory ataxia, ageusia, and dysarthria. Concurrent nephrotic syndrome was identified. Nerve conduction studies supported demyelination. Despite treatment with intravenous methylprednisolone followed by long-term immunosuppression, some disability persisted. Serum archived during his admission tested positive for anti-contactin-1 IgG, with IgG4 as the predominant subclass, in the flow cytometry assay for AN. This case extends the clinical spectrum of AN. Some cases of isolated cranial nerve palsies, especially in the relevant context like nephrotic syndrome, may be attributed to AN. Prompt initiation of more effective therapies, such as rituximab, could significantly improve outcomes. • The clinical spectrum of autoimmune nodopathy (AN) is not fully known. • We describe a case of anti-contactin-1 IgG AN presenting with superior oblique palsy. • Physicians should be aware of the diverse presentations of anti-contactin-1 IgG AN. • Prompt initiation of more effective therapies may optimize therapeutic outcomes. [ABSTRACT FROM AUTHOR]

Background: Although hereditary ataxias are a group of clinically and genetically heterogeneous disorders, specific clinical clues can sometimes incriminate certain genes. This can trigger genetic testing in sporadic patients or prompt dissecting certain genes more thoroughly when initial genetic testing is negative. Also for the assembly of gene panels and interpretation of the results, genotype−phenotype correlations remain important to establish. Methods: We clinically evaluated a Belgian family with autosomal dominant inherited sensory ataxia and variable pyramidal involvement and performed targeted clinical exome sequencing. Secondly, we retrospectively screened sequencing data of an in‐house cohort of 404 patients with neuromuscular disorders for variants in the identified gene RNF170. Results: All affected family members showed sensory ataxia on examination. Pyramidal involvement, and sometimes slow‐pursuit abnormalities and/or a sensory neuropathy, were more variable findings. We identified the heterozygous variant p.Arg199Cys in RNF170 in all three affected siblings of our family. We did not find additional pathogenic variants in RNF170 in our in‐house neuromuscular cohort. Conclusions: We confirm the heterozygous variant p.Arg199Cys in RNF170 in a Belgian family with autosomal dominant sensory ataxia and variable pyramidal involvement. This constitutes a rare but clinically recognizable phenotype that warrants testing of RNF170. Unlike the distinctive bi‐allelic loss of function variants in RNF170 associated with hereditary spastic paraplegia (HSP), the p.Arg199Cys variant is the only one reported in sensory ataxia. It is important for neurologists to be aware of this characteristic phenotype and to include this gene in gene panels for ataxia and HSP. [ABSTRACT FROM AUTHOR]

The cerebellar ataxia, neuropathy and vestibular areflexia syndrome (CANVAS) is a late-onset and recessively inherited ataxia. For many years, CANVAS has been diagnosed based on the clinical phenotype. Only recently, a large biallelic pentanucleotide repeat expansion in the replication factor C subunit 1 (RFC1) gene has been identified as the underlying genetic cause for the large majority of CANVAS cases. Subsequently, other phenotypes such as ataxia with chronic cough, incomplete CANVAS and MSA-C-like phenotypes have been associated with biallelic RFC1 repeat expansions. Because of this heterogeneity it has been suggested to change the name of the disease to "RFC1 disease". Chronic cough is characteristic and can precede neurological symptoms by years or decades. In the neurological examination signs of cerebellar, sensory, and vestibular ataxia are frequently observed. Nerve conduction studies usually show absent or markedly reduced sensory nerve action potentials. On brain MRI cerebellar degeneration and spinal cord alterations are common. In later disease stages more widespread neurodegeneration with additional involvement of the brainstem and basal ganglia is possible. As yet, the exact incidence of RFC1-associated neurological diseases remains uncertain although first studies suggest that RFC1-related ataxia is common. Moreover, the pathophysiological mechanisms caused by the large biallelic pentanucleotide repeat expansions in RFC1 remain elusive. Future molecular and genetic research as well as natural history studies are highly desirable to pave the way towards personalized treatment approaches. [ABSTRACT FROM AUTHOR]

This article from Neurology India discusses a case of subacute combined degeneration of the spinal cord induced by nitrous oxide in a 24-year-old woman. The patient presented with bilateral lower extremity weakness and a physical examination revealed reduced strength. The woman had a history of nitrous oxide use and her vitamin B12 levels were found to be deficient. Treatment with intravenous cyanocobalamin and oral vitamin B12 resulted in significant improvement of symptoms. The article highlights the importance of vitamin B12 in preventing spinal cord degeneration and mentions that nitrous oxide can contribute to vitamin B12 deficiency. [Extracted from the article]