RNA Foci in Two bi-Allelic RFC1 Expansion Carriers.

Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) is a late-onset, autosomal recessive neurodegenerative disorder caused by biallelic AAGGG/ACAGG repeat expansion (AAGGG-exp/ACAGG-exp) in RFC1. The recent identification of patients with CANVAS exhibiting compound heterozygosity for AAGGG-exp and truncating variants supports the loss-of-function of RFC1 in CANVAS patients. We investigated the pathological changes in 2 autopsied patients with CANVAS harboring biallelic ACAGG-exp and AAGGG-exp. RNA fluorescence in situ hybridization of the 2 patients revealed CCTGT- and CCCTT-containing RNA foci, respectively, in neuronal nuclei of tissues with neuronal loss. Our findings suggest that RNA toxicity may be involved in the pathogenesis of CANVAS. ANN NEUROL 2024;95:607-613.

Granuloma, vasculitis, and demyelination in sarcoid neuropathy.

BACKGROUND: Despite the suggestion that direct compression by granuloma and ischemia resulting from vasculitis can cause nerve fiber damage, the mechanisms underlying sarcoid neuropathy have not yet been fully clarified. METHODS: We examined the clinicopathological features of sarcoid neuropathy by focusing on electrophysiological and histopathological findings of sural nerve biopsy specimens. We included 18 patients with sarcoid neuropathy who had non-caseating epithelioid cell granuloma in their sural nerve biopsy specimens. RESULTS: Although electrophysiological findings suggestive of axonal neuropathy were observed, particularly in the lower limbs, all but three patients showed ≥1 abnormalities in nerve conduction velocity or distal motor latency. Additionally, a conduction block was observed in 11 of the 16 patients for whom waveforms were assessed; five of them fulfilled motor nerve conduction criteria strongly supportive of demyelination as defined in the European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) guideline for chronic inflammatory demyelinating polyneuropathy (CIDP). In most patients, sural nerve biopsy specimens revealed a mild to moderate degree of myelinated fiber loss. Fibrinoid necrosis was observed in one patient, and electron microscopy analysis revealed demyelinated axons close to granulomas in six patients. CONCLUSIONS: Patients with sarcoid neuropathy may meet the EAN/PNS electrophysiological criteria for CIDP due to the frequent presence of conduction blocks. Based on our results, in addition to the ischemic damage resulting from granulomatous inflammation, demyelination may play an important role in the mechanism underlying sarcoid neuropathy.

Reduced likelihood of the Poggendorff illusion in cerebellar strokes: a clinical and neuroimaging study.

This study aimed to test our hypothesis that the cerebellum plays an important role in the generation of the optical-geometric illusion known as the Poggendorff illusion, the mechanism of which has been explained by accumulated experience with natural scene geometry. A total of 79 participants, comprising 28 patients with isolated cerebellar stroke, 27 patients with isolated cerebral stroke and 24 healthy controls, performed Poggendorff illusion tasks and 2 different control tasks. We also investigated core brain regions underpinning changes in the experience of the illusion effect using multivariate lesion-symptom mapping. Our results indicate that patients with isolated cerebellar stroke were significantly less likely to experience the Poggendorff illusion effect than patients with isolated cerebral stroke or healthy controls (74.6, 90.5 and 89.8%, respectively; F(2,76) = 6.675, P = 0.002). However, there were no inter-group differences in the control tasks. Lesion-symptom mapping analysis revealed that the brain lesions associated with the reduced frequency of the Poggendorff illusion effect were mainly centred on the right posteromedial cerebellar region, including the right lobules VI, VII, VIII, IX and Crus II. Our findings demonstrated, for the first time, that patients with cerebellar damage were significantly less likely to experience the Poggendorff illusion effect and that right posteromedial cerebellar lesions played an important role in this effect. These results provide new insight into alterations of a geometric illusion effect in patients with cerebellar disorders and pave the way for future clinical use of the illusion task to detect cerebellar abnormalities.

Buccofacial apraxia in primary progressive aphasia.

Buccofacial apraxia (BFA) is associated with nonfluent/agrammatic variant primary progressive aphasia (nfvPPA) as well as with the severity of apraxia of speech (AOS), a core symptom of nfvPPA. However, an association with agrammatism has not been established. The aim of this study was to examine the association between BFA and agrammatism in nfvPPA and to determine differences in atrophic regions in primary progressive aphasia (PPA) with and without BFA. Seventy-four patients with PPA were recruited, including 34, 15, 10, and 15 patients with nfvPPA, semantic variant PPA, logopenic variant PPA, and unclassified PPA, respectively. All patients underwent language examination and BFA evaluations. Voxel-based morphometry (VBM) was performed to determine whether atrophy of a specific lesion correlated with the presence of BFA. BFA was observed in 20 and 3 patients with nfvPPA and unclassified PPA, respectively. In a comparison of patients with nfvPPA with and without BFA, the BFA group showed significantly worse spontaneous speech and writing in the Western Aphasia Battery. The agrammatism ratio or the ratio of agrammatic errors to the total number of particles was higher in the BFA group; however, the severity of prosodic and phonetic components of AOS did not differ between the two groups. VBM showed that the severity of BFA correlated with atrophy of the opercular and triangular areas of the inferior frontal gyrus to a part of the left middle frontal gyrus. BFA has a different anatomical basis from AOS in patients with nfvPPA and that BFA is characterized by more anterior degeneration compared to that of AOS.

Ocular flutter as the presenting manifestation of autoimmune glial fibrillary acidic protein astrocytopathy.

A 39-year-old man exhibited ocular flutter and cerebellar ataxia following a subacute disturbance of consciousness and partial seizure. He was diagnosed with autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy by tissue- and cell-based antibody assays. Brain single-photon emission computed tomography detected a significant increase in blood flow in the fastigial nucleus, a critical region for eye saccade control. Immunotherapies diminished the ocular flutter and reduced hyperperfusion in the fastigial nucleus. This case suggests that autoimmune GFAP astrocytopathy can cause ocular flutter and provides strong imaging evidence supporting the hypothesis that ocular flutter is caused by hyperactivity or disinhibition of the fastigial nucleus.

Relationship between motor learning and gambling propensity in Parkinson's disease.

INTRODUCTION: The basal ganglia and related dopaminergic cortical areas are important neural systems underlying motor learning and are also implicated in impulse control disorders (ICDs). Motor learning impairments and ICDs are frequently observed in Parkinson's disease (PD). Nevertheless, the relationship between motor learning ability and ICDs has not been elucidated. METHODS: We examined the relationship between motor learning ability and gambling propensity, a possible symptom for prodromal ICDs, in PD patients. Fifty-nine PD patients without clinical ICDs and 43 normal controls (NC) were administered a visuomotor rotation perturbation task and the Iowa Gambling Task (IGT) to evaluate motor learning ability and gambling propensity, respectively. Participants also performed additional cognitive assessments and underwent brain perfusion SPECT imaging. RESULTS: Better motor learning ability was significantly correlated with lower IGT scores, i.e., higher gambling propensity, in PD patients but not in NC. The higher scores on assessments reflecting prefrontal lobe function and well-preserved blood perfusion in prefrontal areas were correlated with lower IGT scores along with better motor learning ability. CONCLUSIONS: Our findings suggest that better motor learning ability and higher gambling propensity are based on better prefrontal functions, which are in accordance with the theory that the prefrontal cortex is one of the common essential regions for both motor learning and ICDs.

Ultrasonographic evaluation reveals thinning of cervical nerve roots and peripheral nerves in spinal and bulbar muscular atrophy.

BACKGROUND: Ultrasonography (US) is a noninvasive and patient-friendly tool for the evaluation of peripheral nerves. In motor neuron diseases, amyotrophic lateral sclerosis (ALS) has been reported to show the atrophy of peripheral nerves on US. However, the US findings are still unclear in spinal and bulbar muscular atrophy (SBMA), an adult-onset lower motor neuron disease caused by an abnormal CAG repeat expansion in the androgen receptor gene. METHODS: We prospectively recruited and evaluated 11 patients with genetically confirmed SBMA and 9 patients with ALS diagnosed according to the revised El Escorial ALS criteria or the Awaji electrodiagnostic criteria. The C5-C7 cervical nerve roots and the median and ulnar nerves were evaluated ultrasonographically. RESULTS: The cross-sectional areas (CSAs) of the C6 and C7 nerve roots, the median nerve in the upper arm and forearm, and the ulnar nerve in the upper arm were smaller in patients with SBMA than those in patients with ALS (p < 0.05), whereas the CSAs of the C5 nerve root and the ulnar nerve in the forearm were not smaller. CONCLUSIONS: US showed that the peripheral nerves in patients with SBMA were thinner than those in patients with ALS despite similar degrees of weakness and motor neuron loss. Possible causes include additional sensory nerve involvement and longer disease duration in patients with SBMA than those in patients with ALS.

Sensory Ataxic Guillain-Barré Syndrome with Dysgeusia after mRNA COVID-19 Vaccination.

Guillain-Barré syndrome (GBS) has occasionally occurred in people who have received coronavirus disease 2019 (COVID-19) vaccines. Dysgeusia is rare symptom of GBS. We herein report a rare case of sensory ataxic GBS with dysgeusia just after the second dose of the Pfizer-BioNTech COVID-19 vaccine. Although autoantibodies against glycolipids were not detected, immunotherapy with intravenous immunoglobulin and methylprednisolone pulse therapy effectively ameliorated the symptoms. Our report suggests that the COVID-19 vaccine may induce various clinical subtypes of GBS, including a rare variant with sensory ataxia and dysgeusia.

Seen by a Glance, But Not by a Stare-A Case Study of a Patient With Simultanagnosia.

OBJECTIVE: Simultanagnosia is a rare neuropsychological symptom characterized by difficulty recognizing global structures while preserving perception of local detail. The condition is classified into ventral and dorsal types. Clinical presentation of ventral simultanagnosia includes a reduced ability to recognize multiple visual stimuli rapidly, that is, part-by-part recognition. Here, we report a case of ventral simultanagnosia with a unique presentation; when short-duration visual stimuli were presented, the patient could perform global recognition by improving his part-by-part approach. To investigate the relationship between local and global perception bias and the duration of the present stimulus, we conducted a visual perception test using hierarchically organized Navon figures. METHODS/RESULTS: The patient was a 62-year-old right-handed man who suffered from cerebral infarction in the right occipitotemporal lobe. He had no language dysfunction but exhibited left unilateral neglect, prosopagnosia, and ventral-type simultanagnosia. We conducted a visual perception test using the Navon figures and control figures as a visual stimulus. We randomly presented the figures for intervals of 0.2 or 20 s and let the patient report all the letters (global and/or local element) that he recognized. Global elements of the Navon letter were recognized a rate of 0% and 78.3% at intervals of 20 and 0.2 s, respectively, indicating that shorter presentation made the part-by-part approach less likely to manifest. CONCLUSIONS: We assumed that the simultanagnosia in this case was caused by failure to maintain the initially perceived global information for a long period of time during visual presentation, due to right occipitotemporal damage.

Brain changes underlying progression of speech motor programming impairment.

Aquired apraxia of speech is a disorder that impairs speech production, despite intact peripheral neuromotor function. Its pathomechanism remains to be established. Neurodegenerative lesion models provide an unequalled opportunity to explore the neural correlates of apraxia of speech, which is present in a subset of patients diagnosed with non-semantic variants of primary progressive aphasia. The normalized pairwise variability index, an acoustic measure of speech motor programming, has shown high sensitivity and specificity for apraxia of speech in cross-sectional studies. Here, we aimed to examine the strength of the pairwise variability index and overall word duration (i.e. articulation rate) as markers of progressive motor programming deficits in primary progressive aphasia with apraxia of speech. Seventy-nine individuals diagnosed with primary progressive aphasia (39 with non-fluent variant and 40 with logopenic variant) and 40 matched healthy controls participated. Patients were followed-up annually (range 1-6 years, median number of visits = 2). All participants completed a speech assessment task and a high-resolution MRI. Our analyses investigated trajectories of speech production (e.g. pairwise variablity index and word duration) and associations with cortical atrophy in the patients. At first presentation, word duration differentiated the nonfluent and logopenic cases statistically, but the range of scores overlapped substantially across groups. Longitudinally, we observed progressive deterioration in pairwise variability index and word duration specific to the non-fluent group only. The pairwise variability index showed particularly strong associations with progressive atrophy in speech motor programming brain regions. Of novelty, our results uncovered a key role of the right frontal gyrus in underpinning speech motor programming changes in non-fluent cases, highlighting the importance of right-brain regions in responding to progressive neurological changes in the speech motor network. Taken together, our findings validate the use of a new metric, the pairwise variability index, as a robust marker of apraxia of speech in contrast to more generic measures of speaking rate. Sensitive/specific neuroimaging biomarkers of the emergence and progression of speech impairments will be useful to inform theories of the pathomechanisms underpinning impaired speech motor control. Our findings justify developing more sensitive measures of rhythmic temporal control of speech that may enable confident detection of emerging speech disturbances and more sensitive tracking of intervention-related changes for pharmacological, neuromodulatory and behavioural interventions. A more reliable detection of speech disturbances has relevance for patient care, with predominance of progressive apraxia of speech a high-risk factor for later diagnosis of progressive supranuclear palsy or corticobasal degeneration.

Qualitative Deficits in Verbal Fluency in Parkinson's Disease with Mild Cognitive Impairment: A Clinical and Neuroimaging Study.

BACKGROUND: Mild cognitive impairment (MCI) in Parkinson's disease (PD) is considered a risk factor for PD with dementia (PDD). Verbal fluency tasks are widely used to assess executive function in PDD. However, in cases of PD with MCI (PD-MCI), the relative diagnostic accuracy of different qualitative verbal fluency measures and their related neural mechanisms remain unknown. OBJECTIVE: This study aimed to investigate the relative diagnostic accuracy of qualitative (clustering and switching) verbal fluency strategies and their correlates with functional imaging in PD-MCI. METHODS: Forty-five patients with PD (26 with MCI and 19 without MCI) and 25 healthy controls underwent comprehensive neurocognitive testing and resting-state functional magnetic resonance imaging. MCI in patients with PD was diagnosed according to established clinical criteria. The diagnostic accuracy of verbal fluency measures was determined via receiver operating characteristic analysis. Changes in brain functional connectivity between groups and across clinical measures were assessed using seed-to-voxel analyses. RESULTS: Patients with PD-MCI generated fewer words and switched less frequently in semantic and phonemic fluency tasks compared to other groups. Switching in semantic fluency showed high diagnostic accuracy for PD-MCI and was associated with reduced functional connectivity in the salience network. CONCLUSION: Our results indicate that reduced switching in semantic fluency tasks is a sensitive and specific marker for PD-MCI. Qualitative verbal fluency deficits and salience network dysfunction represent early clinical changes observed in PD-MCI.

Therapeutic efficacy of heparin and direct factor Xa inhibitors in cancer-associated cryptogenic ischemic stroke with venous thromboembolism.

BACKGROUND: Anticoagulation therapy, especially using heparin or recently developed oral direct factor Xa inhibitors (DiXals), is recommended as first-line treatment for cancer-related venous thromboembolism (VTE). However, the preventive efficacy of these anticoagulants for cancer-associated ischemic stroke is still unknown. We retrospectively investigated the efficacy of subcutaneous unfractionated heparin (UFH) and DiXals for preventing the recurrence of cancer-associated cryptogenic ischemic stroke with VTE. METHODS: We retrospectively studied consecutive patients with cancer-associated cryptogenic ischemic stroke and comorbid VTE who received subcutaneous UFH or oral DiXaIs at 9 hospitals. RESULT: Fifty-three patients (24 treated with UFH and 29 treated with DiXaIs) were enrolled. Of these, 47 demonstrated systemic metastasis (cancer stage IV). During 30-day follow-up after initiation of anticoagulation therapy, recurrent ischemic stroke was observed in only 1 patient (4%) in the UFH group and in 9 patients (31%) in the DiXal group. The incidence of major bleeding complications was similar between the 2 groups (4% and 10%, respectively). The cumulative risk of ischemic stroke recurrence within 30 days was lower with UFH than with DiXals (competing risk analysis, p = 0.008). In the DiXal group, patients who experienced recurrence showed significantly higher D-dimer levels than those without recurrence. CONCLUSION: In patients with cancer-associated cryptogenic ischemic stroke and comorbid VTE, UFH demonstrated a lower rate of recurrent ischemic stroke than DiXaIs, and there were no differences in bleeding risk between the 2 treatments. D-dimer levels at stroke onset increased the risk of recurrence in the DiXal group but not in the UFH group.

Neural mechanisms of foreign accent syndrome: Lesion and network analysis.

BACKGROUND: Foreign accent syndrome (FAS) is a rare acquired speech disorder wherein an individual's spoken accent is perceived as "foreign." Most reported cases involve left frontal brain lesions, but it is known that various other lesions can also cause FAS. To determine whether heterogeneous FAS-causing lesions are localized to a common functional speech network rather than to a single anatomical site, we employed a recently validated image analysis technique known as "lesion network mapping." METHODS: We identified 25 published cases of acquired neurogenic FAS without aphasia, and mapped each lesion volume onto a reference brain. We next identified the network of brain regions functionally connected to each FAS lesion using a connectome dataset from normative participants. Network maps were then overlapped to identify common network sites across the lesions. RESULTS: Classical lesion overlap analysis showed heterogeneity in lesion anatomical location, consistent with prior reports. However, at least 80% of lesions showed network overlap in the bilateral lower and middle portions of the precentral gyrus and in the medial frontal cortex. The left lower portion of the precentral gyrus is suggested to be the location of lesions causing apraxia of speech (AOS), and the middle portion is considered to be a larynx-specific motor area associated with the production of vowels and stop/nasal consonants and with the determination of pitch accent. CONCLUSIONS: The lesions that cause FAS are anatomically heterogeneous, but they share a common functional network located in the bilateral posterior region of the frontal lobe. This network specifically includes not only the lower portion of the central gyrus, but also its middle region, which is referred to as the larynx motor cortex and is known to be associated with phonation. Our findings suggest that disrupted networks in FAS might be anatomically different from those in AOS.

Bedside video-oculographic evaluation of eye movements in acute supratentorial stroke patients: A potential biomarker for hemispatial neglect.

BACKGROUND AND PURPOSE: The presence of hemispatial neglect adversely affects functional outcomes in stroke patients; consequently, it warrants early targeted rehabilitative intervention. Nevertheless, hemispatial neglect in the acute phase of stroke has often been underdiagnosed. In this study, we aimed to detect hemispatial neglect at the bedside in acute stroke patients by measuring eye movements using video-oculography (VOG). METHODS: Forty-seven patients with acute unilateral supratentorial stroke were enrolled. We quantitatively measured horizontal saccade (latency, velocity, and amplitude) and smooth pursuit (gain) at the bedside using VOG and compared these variables with scores on the Behavioral Inattention Test (BIT), a screening battery to assess hemispatial neglect. RESULTS: Contralesional saccade latency, velocity, and amplitude, and ipsilesional smooth pursuit gain were suppressed compared with those in the opposite directions (p = 0.08, 0.02, 0.04, and 0.02, respectively). These directional ocular hypokinesia values correlated with the total BIT score (correlation coefficients -0.53, 0.48, 0.51, and 0.39, respectively). The association was significant even after adjusting for age and stroke severity. CONCLUSIONS: Eye movement measurements performed using VOG significantly correlated with the tendency for hemispatial neglect in acute supratentorial stroke patients. Bedside VOG measurement may be a simple biomarker for detecting hemispatial neglect even in patients in the supine position during the acute phase of stroke.

[Foreign Accent Syndrome].

Foreign accent syndrome (FAS) is a rare speech disorder characterized by the emergence of a foreign accent. To date, more than a hundred cases of FAS have been reported, and the impression of accent change is regarded to be the result of a combination of segmental deficits (i.e., phonetic distortions and phonemic paraphasias) and supra-segmental changes (i.e., stress, pitch, or rhythm variation). The most common etiology of FAS is stroke, followed by other causes. Various lesion locations have been identified to cause FAS. Owing to various heterogeneous etiologies and lesion locations, it remains controversial whether there is enough consistency or universality to treat FAS as a "syndrome".

Case Report: Anti-MOG Antibody Seroconversion Accompanied by Dimethyl Fumarate Treatment.

Here we report three cases of anti-myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) mimicking multiple sclerosis in which seropositivity for anti-MOG antibodies occurred during disease-modifying drug dimethyl fumarate (DMF) treatment. These patients developed relapses with anti-MOG antibody seroconversion after switching from fingolimod or steroid pulse therapy to DMF, which was associated with peripheral lymphocyte recovery. MOGAD is considered a humoral immune disease, and DMF reportedly enhances Th2-skewed humoral immune activity. Therefore, we suggest that DMF, but not fingolimod, may exacerbate humoral immune imbalance and enhance autoantibody production, leading to aggravation of MOGAD.

Tonsillectomy Improved Therapeutic Response in Anti-SRP Myopathy With Chronic Tonsillitis.

Chronic tonsillitis has been attracted attention as a source of abnormal immune responses and a possible trigger of autoimmune diseases such as IgA nephritis, IgA vasculitis, palmoplantar pustulosis, psoriasis, rheumatoid arthritis, Behçet's disease, and myositis. Here we present the first report of anti-signal recognition particle antibody-associated necrotizing myopathy (anti-SRP myopathy) with IgA nephropathy and chronic tonsillitis in which the therapeutic response to intravenous immunoglobulin (IVIG) treatment was dramatically improved after tonsillectomy and accompanied by a rapid increase in ΔIgG, defined as the change in serum IgG levels 2 weeks after the start of IVIG treatment relative to pre-treatment levels. Moreover, serum anti-SRP antibody titers became undetectable after tonsillectomy even though the resected tonsils did not produce anti-SRP antibodies. Tonsillectomy should be considered when chronic tonsillitis is observed in patients with autoimmune diseases showing poor response to treatment, including anti-SRP myopathy.

Hepatitis B Virus-related Vasculitic Neuropathy in an Inactive Virus Carrier Treated with Intravenous Immunoglobulin.

We herein report a 33-year-old woman who was an asymptomatic hepatitis B virus (HBV) carrier and presented with distal muscle weakness in the legs and asymmetrical paresthesia in the distal extremities. A nerve biopsy specimen revealed fibrinoid necrosis associated with inflammatory infiltration in the perineural space, and deposition of hepatitis B core antigen and C4d complement was detected in the vascular endothelial cells as well as around the vessels. She was diagnosed with HBV-related vasculitic neuropathy and treated with intravenous immunoglobulin (IVIG). Her symptoms completely subsided after eight weeks. Vasculitic neuropathy rarely develops in the chronic inactive stages of HBV infection. This is the first report of an HBV-inactive carrier with vasculitic neuropathy successfully treated with IVIG.

Non-traumatic Acute Epidural Hematoma in Multiple Sclerosis Treated With Fingolimod.

Fingolimod acts as a functional antagonist of the sphingosine-1-phosphate receptor and is widely used for relapsing-remitting multiple sclerosis (MS). Here we report the first case of non-traumatic acute epidural hematoma in a relapsing-remitting MS patient treated with fingolimod. Fingolimod might increase the risk of hemorrhage by enhancing vasospasm and causing vascular disruption. Switching fingolimod to other disease-modifying drugs, including dimethyl fumarate, should be considered when non-traumatic hemorrhage is observed in MS patients.

Novel VRK1 Mutations in a Patient with Childhood-onset Motor Neuron Disease.

A 24-year-old Japanese man exhibited slowly progressive gait disturbance from childhood to young adulthood. Physical and physiological examinations showed the involvement of both upper and lower motor neurons, fulfilling the diagnostic criteria for amyotrophic lateral sclerosis (ALS). Mild cognitive impairment and subclinical sensory involvement were also observed. A genetic analysis revealed novel compound heterozygous mutations, c.767C>T (p.Thr256Ile) and c.800A>G (p.Asp267Gly), in the vaccinia-related kinase 1 gene (VRK1). This is the first report of a Japanese patient with a motor neuron disease phenotype caused by VRK1 mutations. This diagnosis should be considered in atypical cases of juvenile-onset and slowly progressive types of motor neuron disease.