First evidence of tick-borne encephalitis (TBE) outside of Hokkaido Island in Japan.

Tick-borne encephalitis (TBE) is an infection of the central nervous system caused by the tick-borne encephalitis virus (TBEV). TBE is endemic in parts of Europe and Asia. TBEV is transmitted to humans primarily by Ixodes ticks. There have been 5 TBE cases identified in Japan, all on the northern island of Hokkaido. Rodents with TBEV antibodies and Ixodes ticks have been identified throughout Japan, indicating that TBEV infection might be undiagnosed in Japan. Residual serum and cerebrospinal fluid (CSF) collected in 2010-2021 from 520 patients ≥1 year-of-age previously hospitalized with encephalitis or meningitis of unknown etiology at 15 hospitals (including 13 hospitals outside of Hokkaido) were screened by ELISA for TBEV IgG and IgM antibodies; TBEV infection was confirmed by the gold standard neutralization test. Residual serum was available from 331 (63.6%) patients and CSF from 430 (82.6%) patients; both serum and CSF were available from 189 (36.3%). Two patients were TBE cases: a female aged 61 years hospitalized for 104 days in Oita (2000 km south of Hokkaido) and a male aged 24 years hospitalized for 11 days in Tokyo (1200 km south of Hokkaido). Retrospective testing also identified a previous TBEV infection in a female aged 45 years hospitalized for 12 days in Okayama (1700 km south of Hokkaido). TBEV infection should be considered as a potential cause of encephalitis or meningitis in Japan. TBE cases are likely undiagnosed in Japan, including outside of Hokkaido, due to limited clinical awareness and lack of availability of TBE diagnostic tests.

Granulomatosis with Polyangiitis Presenting with Thrombovasculitic and Necrotizing Pachy- and Leptomeningitis Accompanied by a Brain Tumor-like Lesion.

We report a case of granulomatosis with polyangiitis (GPA) presenting with hypertrophic pachymeningitis with a huge brain tumor-like lesion. A 57-year-old man acutely developed consciousness disturbance. Magnetic resonance imaging revealed a right frontal lobe mass with thickened, contrast-enhanced dura. Computed tomography revealed sinusitis and multiple lung nodules. The presence of proteinase 3-anti-neutrophil cytoplasmic antibody indicated GPA. Histopathology of the excised brain tissues revealed thrombovasculitis with heavy neutrophilic infiltration in the pachy- and leptomeninges covering an ischemic cerebral cortex. The patient improved with corticosteroids and rituximab. Our case warrants considering GPA as a cause of hypertrophic pachymeningitis with brain-tumor like lesions.

Hyperthyroidism-induced Cerebral Venous Thrombosis Presenting as Chronic Isolated Intracranial Hypertension.

A 38-year-old woman with untreated Graves' disease was admitted to our hospital because of headache and diplopia for 3 months. A neuro-ophthalmic examination showed bilateral papilledema and abducens nerve paralysis. The cerebrospinal fluid pressure was extremely high. Brain magnetic resonance imaging showed cerebral venous thrombosis in the superior sagittal and right transverse and sigmoid sinuses. Laboratory investigations revealed elevated factor VIII and von Willebrand factor levels. The patient recovered after propylthiouracil and anticoagulation therapy. We herein report a rare case of cerebral venous thrombosis with hyperthyroidism presenting as chronic isolated intracranial hypertension. Hyperthyroidism can induce a hypercoagulable state and lead to venous thromboembolism.

Multiple brain infarctions and endomyocarditis in ANCA-negative eosinophilic granulomatosis with polyangiitis.

Eosinophilic granulomatosis with polyangiitis (EGPA) is a small vessel necrotizing vasculitis characterized by asthma and eosinophilia. Ischemic stroke is a rare complication of the disease. We herein report a case involving a 77-year-old woman with sinusitis who developed embolic stroke and splenic infarctions. Laboratory tests revealed hypereosinophilia and elevated troponin-T and N-terminal pro-brain natriuretic peptide. Antineutrophil cytoplasmic antibodies (ANCA) studies were negative. Skin biopsy showed infiltration of eosinophils into the arterial walls. These clinicopathological findings led to the diagnosis of EGPA. We also found the evidence of endomyocarditis as revealed by multimodality cardiac imaging. The patient underwent continuous immunosuppressive and anticoagulation therapy, and the infarctions did not recur. This report highlights the importance of histologically proven vasculitis with eosinophil infiltration and careful examination for cardiac involvement, especially in ANCA-negative patients.

Neuropathology of spinocerebellar ataxia type 8: Common features and unique tauopathy.

Spinocerebellar ataxia type 8 (SCA8) is a neurodegenerative condition that presents with several neurological symptoms, such as cerebellar ataxia, parkinsonism, and cognitive impairment. It is caused by a CTA/CTG repeat expansion on chromosome 13q21 (ataxin 8 opposite strand [ATXN8OS]). However, the pathological significance of this expansion remains unclear. Moreover, abnormal CTA/CTG repeat expansions in ATXN8OS have also been reported in other neurodegenerative diseases, including progressive supranuclear palsy. In this study, we analyzed all available autopsy cases in Japan to investigate common pathological features and profiles of tau pathology in each case. Severe neuronal loss in the substantia nigra and prominent loss of Purkinje cells, atrophy of the molecular layer, and proliferation of Bergmann glia in the cerebellum were common features. Regarding tauopathy, one case presented with progressive supranuclear palsy-like 4-repeat tauopathy in addition to mild Alzheimer-type 3- and 4-repeat tauopathy. Another case showed 3- and 4-repeat tauopathy accentuated in the brainstem. The other two cases lacked tauopathy after extensive immunohistochemical studies. The present study confirmed common pathological features of SCA8 as degeneration of the substantia nigra in addition to the cerebellum. Our study also confirmed unique tauopathy in two of four cases, indicating the necessity to further collect autopsy cases.

Neuropathology of classic myotonic dystrophy type 1 is characterized by both early initiation of primary age-related tauopathy of the hippocampus and unique 3-repeat tauopathy of the brainstem.

Myotonic dystrophy type 1 (DM1) is an inherited autosomal-dominant condition that induces altered splicing of transcripts, including MAPT, leading to a distinctive abnormal deposition of tau protein in the CNS. We characterized the tau isoforms of abnormal depositions in the brains of 4 patients with classic DM1 by immunohistochemistry using isoform-specific antibodies. All patients, including those of presenile age, showed numerous neurofibrillary tangles (NFTs) of both 3-repeat and 4-repeat tau in the limbic area and mild involvement in the cerebral cortex. Amyloid-ß deposition was only seen in 1 senile case while cortical tauopathy in all other cases was consistent with primary age-related tauopathy (PART). In the putamen and globus pallidus, only a few tau deposits were observed. Tau deposits in the brainstem frequently showed a DM1-specific pattern with 3-repeat tau dominant NFTs. Additionally, tau-positive astrocytes morphologically similar to tufted astrocytes and astrocytic plaques were occasionally observed in the brainstem; however, they were predominantly composed of 3-repeat tau. Thus, the classic DM1 showed both early onset of PART-like pathology in the limbic areas as a progeroid syndrome of DM1 and an abnormal splicing event in the brainstem leading to 3-repeat tau dominant accumulation with both neuronal and astrocytic involvement.

Paradoxical Cerebellar Embolism Associated with Platypnea-orthodeoxia Syndrome.

Platypnea-orthodeoxia syndrome is a rare clinical entity characterized by dyspnea and arterial blood deoxygenation in a sitting position. An 89-year-old woman was diagnosed with subacute cerebellar infarction. Her blood oxygen saturation decreased to 88% in a sitting position, resulting in dyspnea. Cardiological thoracic computed tomography revealed an unruptured aortic aneurysm, an enlarged ascending aorta, right atrial compression, and counterclockwise rotation of the heart. An anatomical distortion of the atrial septum induced by these abnormalities directed the atrial venous inflow such that the right-left shunt flow was exacerbated in a sitting position.

[An autopsied case of severe varicella zoster virus-associated encephalomyelitis under immunosuppressant therapy].

The patient was a 40-year-old woman who was previously diagnosed with systemic lupus erythematosus and myasthenia gravis and had received prednisolone and tacrolimus for more than 7 years. In February 2017, she noticed pain in her lower back and weakness of the lower limbs, and was referred to our hospital on day 5. She had shingles in the right lower thoracic dermatomes and Brown-Séquard syndrome with right-sided dominant weakness in her lower limbs and left-sided superficial sensory disturbance below the L1 level. Varicella zoster virus (VZV)-associated myelopathy was suspected because of her symptoms and clinical findings. Despite the immediate administration of intravenous acyclovir after hospitalization, she lost consciousness and experienced a seizure related to cerebral hemorrhage in the left temporal lobe on the night of day 5. MRI showed enhanced lesions along the spinal cord and leptomeninges of the brainstem and temporal lobe. VZV-IgG and VZV-DNA were positive in the cerebrospinal fluid. Based on these clinical features and laboratory findings, she was diagnosed as VZV-associated vasculopathy and myelopathy. She subsequently had multiple cerebral infractions and hemorrhage, and developed sudden cardiopulmonary arrest on day 6, culminating in death on day 17. Autopsy showed that inflammatory mononuclear cells had infiltrated the vascular walls of the spinal cord. Immunohistochemistry revealed that some neurons and macrophages in the white matter of the spinal cord were positive for VZV. In addition, atrophic neurons, satellite cells surrounding these neurons, and infiltrating macrophages were immune-positive for VZV at the L2 dorsal root ganglia. These findings were consistent with VZV-associated vasculopathy and myelitis. Under immunosuppressive conditions, VZV can cause shingles and neuronal complications such as vasculopathy and myelitis, which are sometimes fatal despite the immediate administration of intravenous acyclovir. New treatment drugs or drugs to prevent VZV activation are desired.

Dynactin is involved in Lewy body pathology.

Dynactin forms a protein complex with dynein that retrogradely transports cargo along microtubules. Dysfunction of this dynein-dynactin complex causes several neurodegenerative diseases such as Perry syndrome, motor neuron diseases and progressive supranuclear palsy. Recently, we reported colocalization of phosphorylated α-synuclein (p-SNCA) and the largest subunit of dynactin (DCTN1) in Lewy body (LB)-like structures in Perry syndrome. Previous reports have not focused on the relationship between dynactin and synucleinopathies. Thus, we examined autopsied human brains from patients with Parkinson's disease, dementia with LBs, and multiple system atrophy using immunohistochemistry for p-SNCA, DCTN1, dynactin 2 (DCTN2, dynamitin) and dynein cytoplasmic 1 intermediate chain 1 (DYNC1I1). We also examined microtubule affinity-regulating kinases (MARKs), which phosphorylate microtubule-associated proteins and trigger microtubule disruption. Both brainstem-type and cortical LBs were immunopositive for DCTN1, DCTN2, DYNC1I1 and p-MARK and their staining often overlapped with p-SNCA. Lewy neurites were also immunopositive for DCTN1, DCTN2 and DYNC1I1. However, p-SNCA-positive inclusions of multiple system atrophy, which included both glial and neuronal cytoplasmic inclusions, were immunonegative for DCTN1, DCTN2, DYNC1I1 and p-MARK. Thus, immunohistochemistry for dynein-dynactin complex molecules, especially DCTN1, can clearly distinguish LBs from neuronal cytoplasmic inclusions. Our results suggest that dynactin is closely associated with LB pathology.

Mitochondrial dysfunction and altered ribostasis in hippocampal neurons with cytoplasmic inclusions of multiple system atrophy.

Multiple system atrophy (MSA) is a sporadic adult-onset neurodegenerative disease. It has recently been shown that patients with MSA accompanied by cognitive decline display numerous neuronal cytoplasmic inclusions (NCIs) in the limbic neurons. We examined potential mechanisms underlying the formation of these NCIs by determining of mitochondrial function and statuses of RNA processing by analyzing 12 pathologically confirmed cases of MSA. Among them, four had cognitive impairment Semiquantitative evaluation using immunohistochemistry analyses revealed a significantly greater NCI burden in the hippocampal cornu ammonis 1 (CA1) subfield, subiculum, and amygdala in the cases with cognitive impairments compared with those without cognitive impairment. Immunofluorescent staining revealed that limbic neurons with NCIs often accelerated production of reactive oxygen species (ROS) and degraded mitochondrial quality control. Immunofluorescent staining also revealed that neurons with these NCIs translocated heterogeneous nuclear ribonucleoprotein A1 (HNRNPA1) from the nucleus and aggregated abnormally at the perinuclear rim. Since the NCIs in the hippocampal neurons of MSA with cognitive impairments were more numerous, the neuronal mitochondrial dysfunction and altered ribostasis observed in NCI formation may be involved in the hippocampal degeneration of MSA.

Expression of CRYM in different rat organs during development and its decreased expression in degenerating pyramidal tracts in amyotrophic lateral sclerosis.

The protein µ-crystallin (CRYM) is a novel component of the marsupial lens that has two functions: it is a key regulator of thyroid hormone transportation and a reductase of sulfur-containing cyclic ketimines. In this study, we examined changes of the expression pattern of CRYM in different rat organs during development using immunohistochemistry and immunoblotting. As CRYM is reportedly expressed in the corticospinal tract, we also investigated CRYM expression in human cases of amyotrophic lateral sclerosis (ALS) using immunohistochemistry. In the rat brain, CRYM was expressed in the cerebral cortex, basal ganglia, hippocampus and corticospinal tract in the early postnatal period. As postnatal development progressed, CRYM expression was restricted to large pyramidal neurons in layers V and VI of the cerebral cortex and pyramidal cells in the deep layer of CA1 in the hippocampus. Even within the same regions, CRYM-positive and negative neurons were distributed in a mosaic pattern. In the kidney, CRYM was expressed in epithelial cells of the proximal tubule and mesenchymal cells of the medulla in the early postnatal period; however, CRYM expression in the medulla was lost as mesenchymal cell numbers decreased with the rapid growth of the medulla. In human ALS brains, we observed marked loss of CRYM in the corticospinal tract, especially distally. Our results suggest that CRYM may play roles in development of cortical and hippocampal pyramidal cells in the early postnatal period, and in the later period, performs cell-specific functions in selected neuronal populations. In the kidney, CRYM may play roles in maturation of renal function. The expression patterns of CRYM may reflect significance of its interactions with T3 or ketimines in these cells and organs. The results also indicate that CRYM may be used as a marker of axonal degeneration in the corticospinal tract.

[A case of primary central nervous system vasculitis diagnosed by second brain biopsy and treated successfully].

We report a case of primary central nervous system vasculitis (PCNSV) diagnosed by second brain biopsy. A 53-year-old man initially presented with left lateral gaze diplopia. Brain MRI revealed multiple enhanced lesions in the bilateral frontal lobe, bilateral basal ganglia, left cerebellum and brainstem. An initial brain biopsy of the right frontal lobe suggested immune-related encephalitis with angiocentric accumulation of chronic inflammatory cells, while malignant lymphoma could not be completely ruled out. The patient deteriorated despite being treated with repeated methylprednisolone pulse therapy, cyclophosphamide, and plasmapheresis. A second brain biopsy of the right temporal lobe was then performed. The biopsied specimens showed vascular wall disruption and fibrinoid necrosis with perivascular inflammatory infiltrates, mainly composed of CD8-positive T cells, and PCNSV was diagnosed. He was treated with high dose corticosteroids, in combination with methotrexate (8 mg/week), which reduced the brain lesions. As brain biopsy is an essential investigation for the histological diagnosis of PCNSV; subsequent biopsies may be required when a histopathological diagnosis has not been obtained by the first biopsy, and further aggressive therapy is being considered.

A Case of Central Pontine Myelinolysis Caused by Hypophosphatemia Secondary to Refeeding Syndrome.

Central pontine myelinolysis (CPM), which was originally considered to be the result of rapid correction of chronic hyponatremia, is not necessarily accompanied by hyponatremia or drastic changes in serum sodium level. Here, we report a case of an anorexic 55-year-old male with a history of pharyngo-laryngo-esophagogastrectomy, initially hospitalized with status epilepticus. Although his consciousness gradually recovered as we were controlling his convulsion, it deteriorated again with new onset of anisocoria, and magnetic resonance imaging (MRI) at this point revealed CPM. Rapid change of serum sodium or osmolarity, which is often associated with CPM, had not been apparent throughout his hospitalization. Instead, a review of the serum biochemistry test results showed that serum phosphate had drastically declined the day before the MRI first detected CPM. In this case, we suspect that hypophosphatemia induced by refeeding syndrome greatly contributed to the occurrence of CPM.

[A case of Isaacs' syndrome causing various central nervous symptoms successfully treated with high-dose intravenous methylprednisolone therapy].

A 44-year-old man with a bilateral hand tremor suffered from a decline in concentration and abnormal vision for several months. He also complained of easily falling down because of muscle stiffness and cramps in his lower limbs. On admission, he demonstrated lower limb stiffness, muscle cramps, diplopia, hyperhidrosis, left upper limb ataxia and dysesthesia in all limbs. Laboratory examination showed a marked elevation in his serum creatine kinase level (26,890 U/l), and needle electromyography demonstrated myokymic discharges in the muscles of his lower extremities. Isaacs' syndrome was diagnosed based on a positive voltage-gated potassium channel antibody titer of 1,007 pM. Administration of an anticonvulsant (phenytoin, 200 mg/day) did not resolve his symptoms; however, high-dose intravenous methylprednisolone therapy (1 g/day for 3 days) resulted in marked clinical improvement. This case suggests that high-dose intravenous methylprednisolone therapy for Isaacs' syndrome might be as effective as other immunosuppressive therapies such as plasma exchange or intravenous immunoglobulin.

Transient interhemispheric disconnection in a case of insulinoma-induced hypoglycemic encephalopathy.

We report a case of a 22-year-old male who was transferred to our hospital in a comatose state following successive seizures. Low blood glucose had been detected upon his arrival at the previous hospital. He became responsive 12 days after the onset of coma. Upon regaining consciousness he exhibited severe dysarthria and several interhemispheric disconnection signs such as intermanual conflict, left-hand dysgraphia, left hemispatial neglect confined to the right hand, impaired interhemispheric transfer, and unilateral constructional apraxia of the right hand. Brain MRI disclosed T2-weighted and diffusion-weighted hyperintense lesions with reduced apparent diffusion coefficients in the bilateral centrum semiovale, splenium of the corpus callosum, right posterior limb of the internal capsule, and bilateral middle cerebellar peduncles. As the MRI findings vanished, his interhemispheric disconnection signs gradually resolved. Abdominal imaging studies revealed a pancreatic tumor, which was later endocrinologically diagnosed as an insulinoma. This is an extremely rare report of interhemispheric disconnection signs due to hypoglycemic encephalopathy. The lesions in the bilateral centrum semiovale likely contributed to the interhemispheric disconnection signs.

Sequential changes in the non-coding control region sequences of JC polyomaviruses from the cerebrospinal fluid of patients with progressive multifocal leukoencephalopathy.

Progressive multifocal leukoencephalopathy (PML) is caused by JC polyomavirus (JCV) infection in the brain. JCV isolates from PML patients have variable mutations in the non-coding control region (NCCR) of the genome. This study was conducted to examine sequential changes in NCCR patterns of JCV isolates obtained from the cerebrospinal fluid (CSF) of PML patients. CSF specimens were collected from PML patients at different time points, the NCCR sequences were determined, and their compositions were assessed by computer-based analysis. In patients showing a marked increase in JCV load, the most frequent NCCR sequences in the follow-up specimens were different from those in the initial samples. In contrast, the dominant NCCRs in the CSF remained unaltered during the follow-up of individuals in whom the viral load decreased after therapeutic intervention. These data demonstrate that the majority of JCV variants emerge with the progression of PML and that these changes are suppressed when the viral load is decreased.