Reversible encephalitis-like episodes in fragile X-associated tremor/ataxia syndrome: a case report.

BACKGROUND: Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder caused by CGG repeat expansion of FMR1 gene. Both FXTAS and neuronal intranuclear inclusion disease (NIID) belong to polyglycine diseases and present similar clinical, radiological, and pathological features, making it difficult to distinguish these diseases. Reversible encephalitis-like attacks are often observed in NIID. It is unclear whether they are presented in FXTAS and can be used for differential diagnosis of NIID and FXTAS. CASE PRESENTATION: A 63-year-old Chinese male with late-onset gait disturbance, cognitive decline, and reversible attacks of fever, consciousness impairment, dizziness, vomiting, and urinary incontinence underwent neurological assessment and examinations, including laboratory tests, electroencephalogram test, imaging, skin biopsy, and genetic test. Brain MRI showed T2 hyperintensities in middle cerebellar peduncle and cerebrum, in addition to cerebellar atrophy and DWI hyperintensities along the corticomedullary junction. Lesions in the brainstem were observed. Skin biopsy showed p62-positive intranuclear inclusions. The possibilities of hypoglycemia, lactic acidosis, epileptic seizures, and cerebrovascular attacks were excluded. Genetic analysis revealed CGG repeat expansion in FMR1 gene, and the number of repeats was 111. The patient was finally diagnosed as FXTAS. He received supportive treatment as well as symptomatic treatment during hospitalization. His encephalitic symptoms were completely relieved within one week. CONCLUSIONS: This is a detailed report of a case of FXTAS with reversible encephalitis-like episodes. This report provides new information for the possible and rare features of FXTAS, highlighting that encephalitis-like episodes are common in polyglycine diseases and unable to be used for differential diagnosis.

GGC expansions in NOTCH2NLC contribute to Parkinson disease and dopaminergic neuron degeneration.

BACKGROUND AND PURPOSE: The role of GGC repeat expansions within NOTCH2NLC in Parkinson's disease (PD) and the substantia nigra (SN) dopaminergic neuron remains unclear. Here, we profile the NOTCH2NLC GGC repeat expansions in a large cohort of patients with PD. We also investigate the role of GGC repeat expansions within NOTCH2NLC in the dopaminergic neurodegeneration of SN. METHODS: A total of 2,522 patients diagnosed with PD and 1,085 health controls were analyzed for the repeat expansions of NOTCH2NLC by repeat-primed PCR and GC-rich PCR assay. Furthermore, the effects of GGC repeat expansions in NOTCH2NLC on dopaminergic neurons were investigated by using recombinant adeno-associated virus (AAV)-mediated overexpression of NOTCH2NLC with 98 GGC repeats in the SN of mice by stereotactic injection. RESULTS: Four PD pedigrees (4/333, 1.2%) and three sporadic PD patients (3/2189, 0.14%) were identified with pathogenic GGC repeat expansions (larger than 60 GGC repeats) in the NOTCH2NLC gene, while eight PD patients and one healthy control were identified with intermediate GGC repeat expansions ranging from 41 to 60 repeats. No significant difference was observed in the distribution of intermediate NOTCH2NLC GGC repeat expansions between PD cases and controls (Fisher's exact test p-value = 0.29). Skin biopsy showed P62-positive intranuclear NOTCH2NLC-polyGlycine (polyG) inclusions in the skin nerve fibers of patient. Expanded GGC repeats in NOTCH2NLC produced widespread intranuclear and perinuclear polyG inclusions, which led to a severe loss of dopaminergic neurons in the SN. Consistently, polyG inclusions were presented in the SN of EIIa-NOTCH2NLC-(GGC)98 transgenic mice and also led to dopaminergic neuron loss in the SN. CONCLUSIONS: Overall, our findings provide strong evidence that GGC repeat expansions within NOTCH2NLC contribute to the pathogenesis of PD and cause degeneration of nigral dopaminergic neurons.

Utility of labial salivary gland biopsy in the histological diagnosis of neuronal intranuclear inclusion disease.

BACKGROUND AND PURPOSE: Neuronal intranuclear inclusion disease (NIID) poses a diagnostic challenge because of its diverse clinical manifestations. Detection of intranuclear inclusions remains the primary diagnostic criterion for NIID. Skin biopsies have traditionally been used, but concerns exist regarding postoperative complications and scarring. We sought to investigate the diagnostic utility of labial salivary gland biopsy, a less invasive alternative. METHODS: This study included a total of 19 patients and 11 asymptomatic carriers who underwent labial gland biopsies, while 10 patients opted for skin biopsies. All these individuals were confirmed to have pathogenic GGC repeat expansions in the NOTCH2NLC gene. The control group comprised 20 individuals matched for age and sex, all with nonpathogenic GGC repeat expansions, and their labial gland tissue was sourced from oral surgery specimens. RESULTS: Labial gland biopsies proved to be a highly effective diagnostic method in detecting eosinophilic intranuclear inclusions in NIID patients. The inclusions showed positive staining for p62 and ubiquitin, confirming their pathological significance. The presence of uN2CpolyG protein in the labial gland tissue further supported the diagnosis. Importantly, all patients who underwent lip gland biopsy experienced fast wound healing without any noticeable scarring. In contrast, skin biopsies led to varying degrees of scarring and one instance of a localized infection. CONCLUSION: Labial salivary gland biopsy emerged as a minimally invasive, efficient diagnostic method for NIID, with rapid healing and excellent sensitivity.

Pathologic changes in neuronal intranuclear inclusion disease are linked to aberrant FUS interaction under hyperosmotic stress.

CGG repeat expansion in NOTCH2NLC is the genetic cause of neuronal intranuclear inclusion disease (NIID). Previous studies indicated that the CGG repeats can be translated into polyglycine protein (N2CpolyG) which was toxic to neurons by forming intranuclear inclusions (IIs). However, little is known about the factors governing polyG IIs formation as well as its molecular pathogenesis. Considering that neurogenetic disorders usually involve interactions between genetic and environmental stresses, we investigated the effect of stress on the formation of IIs. Our results revealed that under hyperosmotic stress, N2CpolyG translocated from the cytoplasm to the nucleus and formed IIs in SH-SY5Y cells, recapitulating the pathological hallmark of NIID patients. Furthermore, N2CpolyG interacted/ co-localized with an RNA-binding protein FUS in the IIs of cellular model and NIID patient tissues, thereby disrupting stress granule formation in cytoplasm under hyperosmotic stress. Consequently, dysregulated expression of microRNAs was found both in NIID patients and cellular model, which could be restored by FUS overexpression in cultured cells. Overall, our findings indicate a mechanism of stress-induced pathological changes as well as neuronal damage, and a potential strategy for the treatment of NIID.

Skin biopsy and neuronal intranuclear inclusion disease.

Neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disease with variable clinical phenotypes. There is a considerable delay in the definite diagnosis, which primarily depends on postmortem brain pathological examination. Although CGG repeat expansion in the 5'-untranslated region of NOTCH2NLC has been identified as a disease-associated variant, the pathological diagnosis is still required in certain NIID cases. Intranuclear inclusions found in the skin tissue of patients with NIID dramatically increased its early detection rate. Skin biopsy, as a minimally invasive method, has become widely accepted as a routine examination to confirm the pathogenicity of the repeat expansion in patients with suspected NIID. In addition, the shared developmental origin of the skin and nerve system provided a new insight into the pathological changes observed in patients with NIID. In this review, we systematically discuss the role of skin biopsy for NIID diagnosis, the procedure of skin biopsy, and the pathophysiological mechanism of intranuclear inclusion in the skin.

Diffuse argyrophilic grain disease with TDP-43 proteinopathy and neuronal intermediate filament inclusion disease: FTLD with mixed tau, TDP-43 and FUS pathologies.

Frontotemporal lobar degeneration (FTLD) is a group of disorders characterized by degeneration of the frontal and temporal lobes, leading to progressive decline in language, behavior, and motor function. FTLD can be further subdivided into three main subtypes, FTLD-tau, FTLD-TDP and FTLD-FUS based which of the three major proteins - tau, TDP-43 or FUS - forms pathological inclusions in neurons and glia. In this report, we describe an 87-year-old woman with a 7-year history of cognitive decline, hand tremor and gait problems, who was thought to have Alzheimer's disease. At autopsy, histopathological analysis revealed severe neuronal loss, gliosis and spongiosis in the medial temporal lobe, orbitofrontal cortex, cingulate gyrus, amygdala, basal forebrain, nucleus accumbens, caudate nucleus and anteromedial thalamus. Tau immunohistochemistry showed numerous argyrophilic grains, pretangles, thorn-shaped astrocytes, and ballooned neurons in the amygdala, hippocampus, parahippocampal gyrus, anteromedial thalamus, insular cortex, superior temporal gyrus and cingulate gyrus, consistent with diffuse argyrophilic grain disease (AGD). TDP-43 pathology in the form of small, dense, rounded neuronal cytoplasmic inclusion with few short dystrophic neurites was observed in the limbic regions, superior temporal gyrus, striatum and midbrain. No neuronal intranuclear inclusion was observed. Additionally, FUS-positive inclusions were observed in the dentate gyrus. Compact, eosinophilic intranuclear inclusions, so-called "cherry spots," that were visible on histologic stains were immunopositive for α-internexin. Taken together, the patient had a mixed neurodegenerative disease with features of diffuse AGD, TDP-43 proteinopathy and neuronal intermediate filament inclusion disease. She met criteria for three subtypes of FTLD: FTLD-tau, FTLD-TDP and FTLD-FUS. Her amnestic symptoms that were suggestive of Alzheimer's type dementia are best explained by diffuse AGD and medial temporal TDP-43 proteinopathy, and her motor symptoms were likely explained by neuronal loss and gliosis due to tau pathology in the substantia nigra. This case underscores the importance of considering multiple proteinopathies in the diagnosis of neurodegenerative diseases.

First case of adult onset neuronal intranuclear inclusion disease with both typical radiological signs and NOTCH2NLC repeat expansions in a Caucasian individual.

BACKGROUND AND PURPOSE: Adult onset neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disorder with a heterogeneous clinical presentation that can mimic stroke and various forms of dementia. To date, it has been described almost exclusively in Asian individuals. METHODS: This case presentation includes magnetic resonance imaging (MRI) of the neurocranium, histology by skin biopsy, and long-read genome sequencing. RESULTS: A 75-year-old Caucasian female presented with paroxysmal encephalopathy twice within a 14-month period. Brain MRI revealed high-intensity signals at the cerebral corticomedullary junction (diffusion-weighted imaging) and the paravermal area (fluid-attenuated inversion recovery), a typical distribution observed in adult onset NIID. The diagnosis was corroborated by skin biopsy, which demonstrated eosinophilic intranuclear inclusion bodies, and confirmed by long-read genome sequencing, showing an expansion of the GGC repeat in exon 1 of NOTCH2NLC. CONCLUSIONS: Our case proves adult onset NOTCH2NLC-GGC-positive NIID with typical findings on MRI and histology in a Caucasian patient and underscores the need to consider this diagnosis in non-Asian individuals.

NOTCH2NLC GGC repeat expansion causes retinal pathology with intranuclear inclusions throughout the retina and causes visual impairment.

The retinal pathology of genetically confirmed neuronal intranuclear inclusion disease (NIID) is yet unknown. We report the ocular findings in four NIID patients with NOTCH2NLC GGC repeat expansion to investigate the pathology of retinopathy. All four NIID patients were diagnosed by skin biopsy and NOTCH2NLC GGC repeat analysis. Ocular findings in patients with NIID were studied using fundus photographs, optical coherence tomographic images (OCT), and full-field electroretinograms (ERGs). The histopathology of the retina was studied on autopsy samples from two cases with immunohistochemistry. All patients had an expansion of the GGC repeat (87-134 repeats) in the NOTCH2NLC. Two patients were legally blind and had been diagnosed with retinitis pigmentosa prior to the diagnosis of NIID and assessed with whole exome sequencing to rule out comorbidity with other retinal diseases. Fundus photographs around the posterior pole showed chorioretinal atrophy in the peripapillary regions. OCT showed thinning of the retina. ERGs showed various abnormalities in cases. The histopathology of autopsy samples showed diffusely scattered intranuclear inclusions throughout the retina from the retinal pigment epithelium to the ganglion cell layer, and optic nerve glial cells. And severe gliosis was observed in retina and optic nerve. The NOTCH2NLC GGC repeat expansion causes numerous intranuclear inclusions in the retina and optic nerve cells and gliosis. Visual dysfunction could be the first sign of NIID. We should consider NIID as one of the causes of retinal dystrophy and investigate the GGC repeat expansion in NOTCH2NLC.

NOTCH2NLC mutation-positive neuronal intranuclear inclusion disease with retinal dystrophy: A case report and literature review.

INTRODUCTION: Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disorder that produces a broad spectrum of clinical conditions such as dementia, upper motor neuron involvement, extrapyramidal symptoms, and neuropathy. Some studies have reported ophthalmological conditions associated with the disease; however, the details of these conditions remain unclear. PATIENT CONCERNS: We report a 63-year-old Japanese female with cognitive decline, blurred vision, photophobia, and color blindness at 52 years of age who was diagnosed with cone dystrophy. She also had anxiety, insomnia, depression, delusions, hallucinations, a wide-based gait with short steps, and urinary incontinence. DIAGNOSES, INTERVENTIONS, AND OUTCOMES: Magnetic resonance imaging revealed diffuse cerebral white matter changes and subcortical hyperintensity on diffusion-weighted imaging. Skin biopsy showed p62-positive intranuclear inclusions in sweat glands. NOTCH2NLC gene analysis revealed abnormal GGC expansion; therefore, NIID was diagnosed. CONCLUSION: NOTCH2NLC mutation-positive NIID may be associated with retinal dystrophy. Brain magnetic resonance imaging and skin biopsy are helpful diagnostic clues, and gene analysis is crucial for accurate diagnosis and appropriate management.

A comprehensive study of clinicopathological and genetic features of neuronal intranuclear inclusion disease.

BACKGROUND: The discovery of skin intranuclear inclusions and GGC repeat expansion of NOTCH2NLC has greatly promoted the diagnosis of neuronal intranuclear inclusion disease (NIID). With highly heterogeneous clinical manifestations, NIID patients tend to be underdiagnosed at early stages. METHODS: This study comprehensively studied clinical manifestations, magnetic resonance imaging (MRI), and peripheral nerve conduction in 24 NIID and 166 other neurodegenerative disease (ND) subjects. The nomogram was plotted using the "rms" package, and the t-distributed stochastic neighbor embedding algorithm was performed. Associations between skin intranuclear inclusions and NOTCH2NLC GGC repeats were further analyzed. RESULTS: The clinical, MRI, and peripheral nerve conduction features seriously overlapped in NIID and ND patients; they were assigned variables according to their frequency and specificity in NIID patients. A nomogram that could distinguish NIID from ND was constructed according to the assigned variables and cutoff values of the above features. The occurrence of skin intranuclear inclusions and NOTCH2NLC GGC repeats ≥ 60 showed 100% consistency, and intranuclear inclusion frequency positively correlated with NOTCH2NLC GGC repeats. A hierarchical diagnostic flowchart for definite NIID was further established. CONCLUSION: We provide a novel nomogram with the potential to realize early identification and update the diagnostic flowchart for definitive diagnosis. Moreover, this is the first study to define the association between skin pathology and NOTCH2NLC genetics in NIID.

Three-dimensional structural analysis of papillary thyroid carcinoma nuclei with serial block-face scanning electron microscopy (SBF-SEM).

Nuclear morphology of carcinoma cells is critical for the pathological diagnosis of papillary thyroid carcinoma (PTC). However, three-dimensional architecture of PTC nuclei is still elusive. In this study, we analyzed the three-dimensional ultrastructure of PTC nuclei using serial block-face scanning electron microscopy which takes advantage of the high-throughput acquisition of serial electron microscopic images and three-dimensional reconstruction of subcellular structures. En bloc-stained and resin-embedded specimens were prepared from surgically removed PTCs and normal thyroid tissues. We acquired two-dimensional images from serial block-face scanning electron microscopy and reconstructed three-dimensional nuclear structures. Quantitative comparisons showed that the nuclei of carcinoma cells were larger and more complex than those of normal follicular cells. The three-dimensional reconstruction of carcinoma nuclei divided intranuclear cytoplasmic inclusions into "open intranuclear cytoplasmic inclusions" connecting to cytoplasm outside the nucleus and "closed intranuclear cytoplasmic inclusions" without that connection. Cytoplasm with abundant organelles was observed in open inclusions, but closed inclusions contained fewer organelles with or without degeneration. Granules with a dense core were only observed in closed inclusions. Our observations suggested that open inclusions originate from nuclear invaginations, and disconnection from cytoplasm leads to closed inclusions.

The clinical characteristics of neuronal intranuclear inclusion disease and its relation with inflammation.

BACKGROUND: Neuronal intranuclear inclusion disease (NIID) is a great imitator with a broad spectrum of clinical manifestations that include dementia, parkinsonism, paroxysmal symptoms, peripheral neuropathy, and autonomic dysfunction. Hence, it may also masquerade as other diseases such as Alzheimer's disease, Parkinson's disease, and Charcot-Marie-Tooth disease. Recent breakthroughs on neuroimaging, skin biopsy, and genetic testing have facilitated the diagnosis. However, early identification and effective treatment are still difficult in cases of NIID. OBJECTIVE: To further study the clinical characteristics of NIID and investigate the relationship between NIID and inflammation. METHODS: We systematically evaluated the clinical symptoms, signs, MRI and electromyographical findings, and pathological characteristics of 20 NIID patients with abnormal GGC repeats in the NOTCH2NLC gene. Some inflammatory factors in the patients were also studied. RESULTS: Paroxysmal symptoms such as paroxysmal encephalopathy, stroke-like episodes, and mitochondrial encephalomyopathy lactic acidosis and stroke (MELAS)-like episode were the most common phenotypes. Other symptoms such as cognitive dysfunction, neurogenic bladder, tremor, and vision disorders were also suggestive of NIID. Interestingly, not all patients showed apparent diffusion-weighted imaging (DWI) abnormality or intranuclear inclusions, while abnormal GGC repeats of NOTCH2NLC were seen in all patients. And fevers were noticed in some patients during encephalitic episodes, usually with increasing leukocyte counts and neutrophil ratios. Both IL-6 (p = 0.019) and TNF-α (p = 0.027) levels were significantly higher in the NIID group than in normal controls. CONCLUSION: Genetic testing of NOTCH2NLC may be the best choice in the diagnosis of NIID. Inflammation might be involved in the pathogenesis of NIID.

NOTCH2NLC GGC Repeat Expansion in Patients With Vascular Leukoencephalopathy.

BACKGROUND: Neuronal intranuclear inclusion disease (NIID), caused by GGC (guanine-guanine-cytosine) repeat expansion in NOTCH2NLC, has several clinical and radiological features akin to cerebral small vessel disease (cSVD). The present study tested the hypothesis that NOTCH2NLC GGC expansion may contribute to cSVD. METHODS: One hundred and ninety-seven unrelated patients with genetically unsolved vascular leukoencephalopathy without NOTCH3, HTRA1, and mitochondrial m.3243A>G mutations and 730 healthy individuals were screened for NOTCH2NLC GGC repeat expansion using repeat-primed polymerase chain reaction, fragment analysis, Southern blot analysis, or nanopore sequencing with Cas9 (CRISPR associated protein 9)-mediated enrichment. The clinical and neuroimaging features of the patients were compared between individuals with and without NOTCH2NLC GGC repeat expansion. RESULTS: Six of the 197 (3.0%) patients with unsolved vascular leukoencephalopathy and none of the controls carried the GGC repeat expansion (P=0.00009). Skin biopsy of 1 patient revealed eosinophilic, ubiquitin-positive, and p62-positive intranuclear inclusions in the cells of sweat gland and capillary, providing pathologic evidence for the involvement of small vessels in NIID. For the 6 patients, gait disturbance and cognitive decline were common manifestations with a median onset age of 65 (59-69) years. They all had multiple neuroimaging features suggestive of cSVD, including diffuse white matter hyperintensities, lacunes, and enlarged perivascular space in all 6 patients, cerebral microbleeds in 5, and old intracerebral hemorrhage in 4. Four patients had linear hyperintensity in the corticomedullary junction on diffusion-weighted imaging-the characteristic neuroimaging feature of NIID. There was no difference in the severity of cSVD imaging features between the patients with and without the GGC expansion but more pronounced brain atrophy in the patients with the GGC expansion. CONCLUSIONS: NOTCH2NLC GGC repeat expansion accounted for 3% of genetically unsolved Taiwanese vascular leukoencephalopathy cases after excluding participants with cerebral autosomal dominant arteriopathy with subcortical infarct and leukoencephalopathy (CADASIL), cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), and mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS). NIID should be considered in patients manifesting cSVD, especially in those with characteristic neuroimaging feature of NIID.

Clinical, radiological, and molecular analyses of neuronal intranuclear inclusion disease with polyglycine inclusions.

Neuronal intranuclear inclusion disease (NIID) is a clinically complex neurological disorder that appears sporadically or autosomally. Expansions of intronic GGC trinucleotide repeats in the NOTCH2 N-terminal-like C (NOTCH2NLC) gene cause NIID. In this study, to clarify the clinical characteristics useful for the differential diagnosis of NIID, clinical data of neurological examination, neuroimaging, and nerve conduction studies of six NIID patients diagnosed by pathological or genetic investigations were analyzed. Clinically useful characteristics for diagnosing NIID include general hyporeflexia, episodic disturbance of consciousness, sensory disturbance, miosis, and dementia. Furthermore, neuroimaging findings, such as leukoencephalopathy in T2-weighted magnetic resonance imaging and a linear high intensity of subcortical U-fibers in diffusion-weighted imaging (DWI), as well as decreased motor nerve conduction velocity, are especially important biomarkers for NIID. However, it is necessary to remember that these features may not always be present, as shown in one of the cases who did not have a DWI abnormality in this study. This study also investigated whether expanded GGC repeats were translated into polyglycine. Immunohistochemical analysis using a custom antibody raised against putative C-terminal polypeptides followed by polyglycine of uN2CpolyG revealed that polyglycines were localized in the intranuclear inclusions in skin biopsy specimens from all six patients, suggesting its involvement in the pathogenesis of NIID.

Skin biopsies for diagnosing neuronal intranuclear inclusion disease: A retrospective study of 12 cases.

Neuronal intranuclear inclusion disease (NIID) is a progressive neurodegenerative condition. Skin biopsies taken from the lower leg were reported to be a standard diagnostic procedure for NIID; however, no studies have addressed the optimal skin biopsy locations. We retrospectively analyzed 12 cases in which skin biopsies were performed for diagnosing NIID. We collected clinical information including age, sex, skin biopsy site, the presence of nuclear inclusion bodies, the results of p62 immunostaining, the final diagnosis from the department of neurology, and the presence of abnormal GGC repeats in the NOTCH2NLC gene. Four of the 12 cases had a final diagnosis of NIID. One of the four cases was biopsied from the lower leg, whereas the other three cases were biopsied from the abdomen or thigh. Biopsy specimens of the four definite NIID cases revealed the average rates of nuclear inclusion body-positive cells in adipocytes, sweat gland cells, and fibroblasts to be 13.2%, 10.3%, and 6.3%, respectively. GGC repeat abnormalities in the NOTCH2NLC gene were observed in two of the four cases. The present study indicates that sites with ample subcutaneous fat tissue could be promising for diagnostic skin biopsies for NIID.

Neuronal intranuclear inclusion disease mimicking progressive supranuclear palsy.

BACKGROUND: Given the variable nature of clinical manifestations, neuronal intranuclear inclusion disease (NIID) is regarded as a heterogeneous disease which is challenging to diagnose early. To the present, progressive supranuclear palsy (PSP)-like symptoms have never been listed in the performance of NIID. CASE PRESENTATION: A 58-year-old man presented with progressive Parkinsonism and postural instability for 3 years. Initially, he was considered as probable PSP due to vertical supranuclear gaze palsy, postural instability, and hummingbird sign. No high-intensity signal on diffusion-weighted imaging (DWI) was revealed. Eventually, the diagnosis was revised to NIID by Notch 2 N-terminal like C (NOTCH2NLC) GGC repeat expansions and skin biopsy showing intranuclear eosinophilic inclusions in the vesicles and ductal epithelial cells of sweat glands. CONCLUSION: Even if the typical high-intensity along the corticomedullary junction (CMJ) on DWI is lacking, clinicians should be alert to the possibility of NIID when PSP-like symptoms develop. This case report offers new features of NIID and expands its clinical spectrum.

The clinical and neuroimaging features of sporadic adult-onset neuronal intranuclear inclusion disease.

BACKGROUND: Neuronal intranuclear inclusion disease (NIID) is a rare slowly progressive neurodegenerative disorder that is characterized pathologically by the presence of eosinophilic intranuclear inclusions. NIID is a heterogeneous disease with diverse clinical manifestations, making diagnosis difficult. Here, we analyzed the clinical, pathological, and radiological features of Chinese NIID patients to improve our understanding of NIID. METHODS: A total of 17 patients with sporadic NIID were recruited from the Ruijin Hospital Database between 2014 and 2021. Clinical patient information and brain MRI data were collected. All of the patients underwent standard skin biopsy procedures. RESULTS: The average age of onset for symptoms was 60.18 years, and the average duration of illness was 4.06 years. All patients were diagnosed with NIID due to the presence of intranuclear inclusions confirmed by skin biopsy. Tremor was the most common initial symptom. The average ages at onset and at diagnosis were both lower in patients with tremor than in patients without tremor. NIID may be a systemic disease that affects multiple organs, for one patient had a history of chronic renal insufficiency for more than 10 years. In addition to high-intensity U-fibers signals on diffusion-weighted imaging, there were several other MRI findings, such as focal leukoencephalopathy and cortical swelling. Encephalitic episodes followed by reversible leukoencephalopathy was another important imaging feature of NIID. CONCLUSION: The clinical manifestations of NIID are highly variable. Tremor may be the most common initial symptom in certain cohorts. Encephalitic episodes followed by reversible asymmetric leukoencephalopathy may also indicate this disease.

Neuropathological features of adult-onset neuronal intranuclear inclusion disease with fluid-attenuated inversion recovery high-intensity signals in the cerebellar paravermal area from an early stage: A case report.

Neuronal intranuclear inclusion disease (NIID) is a neurological disorder characterized by eosinophilic intranuclear inclusions (INI) in systemic organs and various cell types. High-intensity signals along the corticomedullary junction on diffusion-weighted imaging and presence of cellular p62-INI in skin biopsy are known indicators for NIID. Furthermore, GGC repeat expansion in NOTCH2NLC is a characteristic genetic alteration in patients with NIID. This report presents the clinical and detailed pathological features of a male older adult with NIID. We also confirmed the presence of fluid-attenuated inversion recovery high-intensity signals in the cerebellar paravermal area, showing similar pathological changes in high-intensity signals along the corticomedullary junction on diffusion-weighted imaging.

First detailed case report of a pediatric patient with neuronal intranuclear inclusion disease diagnosed by NOTCH2NLC genetic testing.

INTRODUCTION: Neuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disease characterized clinically by eosinophilic hyaline intranuclear inclusions in neuronal and other somatic cells. Skin biopsies are reportedly useful in diagnosing NIID, and the genetic cause of NIID was identified as a GGC repeat expansion in NOTCH2NLC in recent years. The number of adult patients diagnosed via genetic testing has increased; however, there have been no detailed reports of pediatric NIID cases with GGC expansions in NOTCH2NLC. This is the first detailed report of a pediatric patient showing various neurological symptoms from the age of 10 and was ultimately diagnosed with NIID via skin biopsy and triplet repeat primed polymerase chain reaction analyses. CASE REPORT: This was an 18-year-old female who developed cyclic vomiting, distal dominant muscle weakness, and sustained miosis at 10 years. Nerve conduction studies revealed axonal degeneration, and her neuropathy had slowly progressed despite several rounds of high-dose methylprednisolone and intravenous immunoglobulin therapy. At 13 years, she had an acute encephalopathy-like episode. At 15 years, brain MRI revealed slightly high-intensity lesions on diffusion-weighted and T2-weighted imaging in the subcortical white matter of her frontal lobes that expanded over time. At 16 years, esophagography, upper gastrointestinal endoscopy, and esophageal manometry revealed esophageal achalasia, and per-oral endoscopic myotomy was performed. At 18 years, we diagnosed her with NIID based on the findings of skin specimen analyses and a GGC repeat expansion in NOTCH2NLC. CONCLUSION: NIID should be considered as a differential diagnosis in pediatric patients with various neurological symptoms.

Acute Reversible Encephalopathy with Neuronal Intranuclear Inclusion Disease Diagnosed by a Brain Biopsy: Inferring the Mechanism of Encephalopathy from Radiological and Histological Findings.

A 75-year-old man presented with headache and disturbance of consciousness. Magnetic resonance imaging revealed edema localized mainly in the cortex and linear contrast enhancement. A brain biopsy revealed numerous astrocytes with inclusion, and genetic testing demonstrated prolonged GGC repeats in NOTCH2NLC. The present case provided two novel insights into the mechanism underlying encephalopathy associated with neuronal intranuclear inclusion disease. First, the histological findings at a site with contrast enhancement on magnetic resonance imaging did not demonstrate any organic association, such as the presence of inflammation or ischemic changes. Second, the imaging and cerebrospinal fluid findings demonstrated increased cerebral blood flow and opening of the blood-brain barrier, indicating the cause of the cerebral swelling.