Anterior horn damage in brachial multisegmental amyotrophy with superficial siderosis and dural tear: an autopsy case report.

BACKGROUND: Patients with superficial siderosis (SS) rarely show brachial multisegmental amyotrophy with ventral intraspinal fluid collection accompanied with dural tear. CASE PRESENTATION: We describe spinal cord pathology of a 58-year-old man who developed brachial multisegmental amyotrophy with ventral intraspinal fluid collection from the cervical to lumbar spinal levels accompanied with SS, dural tear, and snake-eyes appearance on magnetic resonance imaging (MRI). Radiological and pathological analyses detected diffuse and prominent superficial deposition of hemosiderin in the central nervous system. Snake-eyes appearance on MRI expanded from the C3 to C7 spinal levels without apparent cervical canal stenosis. Pathologically, severe neuronal loss at both anterior horns and intermediate zone was expanded from the upper cervical (C3) to middle thoracic (Th5) spinal gray matter, and these findings were similar to compressive myelopathy. CONCLUSION: Extensive damage of the anterior horns in our patient may be due to dynamic compression induced by ventral intraspinal fluid collection.

Repeat conformation heterogeneity in cerebellar ataxia, neuropathy, vestibular areflexia syndrome.

Cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) is a late-onset, slow-progressing multisystem neurodegenerative disorder. Biallelic AAGGG repeat expansion in RFC1 has been identified as causative of this disease, and repeat conformation heterogeneity (ACAGG repeat) was also recently implied. To molecularly characterize this disease in Japanese patients with adult-onset ataxia, we accumulated and screened 212 candidate families by an integrated approach consisting of flanking PCR, repeat-primed PCR, Southern blotting and long-read sequencing using Sequel II, GridION or PromethION. We identified 16 patients from 11 families, of whom seven had ACAGG expansions [(ACAGG)exp/(ACAGG)exp] (ACAGG homozygotes), two had ACAGG and AAGGG expansions [(ACAGG)exp/(AAGGG)exp] (ACAGG/AAGGG compound heterozygotes) and seven had AAGGG expansions [(AAGGG)exp/(AAGGG)exp] (AAGGG homozygotes). The overall detection rate was 5.2% (11/212 families including one family having two expansion genotypes). Long-read sequencers revealed the entire sequence of both AAGGG and ACAGG repeat expansions at the nucleotide level of resolution. Clinical assessment and neuropathology results suggested that patients with ACAGG expansions have similar clinical features to previously reported patients with homozygous AAGGG expansions, although motor neuron involvement was more notable in patients with ACAGG expansions (even if one allele was involved). Furthermore, a later age of onset and slower clinical progression were implied in patients with ACAGG/AAGGG compound heterozygous expansions compared with either ACAGG or AAGGG homozygotes in our very limited cohort. Our study clearly shows the occurrence of repeat conformation heterogeneity, with possible different impacts on the affected nervous systems. The difference in disease onset and progression between compound heterozygotes and homozygotes might also be suspected but with very limited certainty due to the small sample number of cases in our study. Studies of additional patients are needed to confirm this.

Pseudohypoxic brain swelling and secondary hydrocephalus with pseudomeningocele after lumbar surgery: a case report.

BACKGROUND: Postoperative intracranial complications are rare in spine surgery not including cranial procedures. We describe an uncommon case of pseudohypoxic brain swelling (PHBS) and secondary hydrocephalus after transforaminal lumbar interbody fusion (TLIF) presenting as impaired consciousness and repeated seizures. CASE PRESENTATION: A 65-year-old man underwent L4-5 TLIF for lumbar spondylolisthesis and began experiencing generalized seizures immediately postoperatively. Computed tomography (CT) revealed diffuse cerebral edema-like hypoxic ischemic encephalopathy. He was transported to our hospital, at which time epidural drainage was halted and anti-edema therapy was commenced. His impaired consciousness improved. However, he suffered secondary hydrocephalus due to continuous bleeding from a dural defect and spinal epidural fluid collection 3 months later. Following the completion of dural repair and insertion of a ventriculoperitoneal shunt, his neurologic symptoms and neuroimaging findings improved significantly. CONCLUSIONS: PHBS can be considered in patients with unexpected neurological deterioration following lumbar spine surgery even with the absence of documented durotomy. This might be due to postoperative intracranial hypotension-associated venous congestion, and to be distinguished from the more common postoperative cerebral ischemic events-caused by arterial or venous occlusions-or anesthetics complications.

Taste disorder in facial onset sensory and motor neuronopathy: a case report.

BACKGROUND: Taste disorder is a common symptom in the general population. Several studies have shown that patients with neurological disorders, such as amyotrophic lateral sclerosis and Parkinson's disease, develop taste disturbance. Facial onset sensory and motor neuronopathy (FOSMN) is a rare disease characterized by sensory disturbance and weakness spreading from the face to the limbs caudally. We describe a patient with FOSMN who showed taste disorder as the sole initial symptom. CASE PRESENTATION: A 49-year-old man who smoked cigarettes developed taste disturbance. Despite using zinc supplements, an herbal medication, and an ointment, his taste disorder worsened. 4 years later, a tingling feeling emerged at the tip of his tongue and gradually spread to his entire lips. At 55 years of age, he showed difficulty in swallowing, followed by facial paresthesia, muscle atrophy, and weakness in the face and upper limbs without apparent upper motor neuron sign. Cessation of smoking did not improve his taste disturbance, and he was unable to discriminate different tastes on the entire tongue. In an electrogustometric study, electrical stimulation did not induce any type of taste sensation. Blink reflex showed delayed or diminished R2 responses. Needle electromyography revealed severe chronic neurogenic changes in the tongue and masseter muscles. Mild chronic neurogenic changes were also observed in the limbs. In the thoracic paraspinal muscles, active neurogenic changes were detected. Findings of hematological and cerebrospinal fluid analyses, and magnetic resonance images of the brain and spinal cord were unremarkable. One cycle of intravenous immunoglobulin therapy did not improve his symptoms. We diagnosed him as having FOSMN with the sole initial symptom of taste disorder. Nine years after the onset of taste disorder, he developed impaired sensation of touch in the right upper limb and required tube feeding and ventilator support. CONCLUSION: Taste disorder can be the initial manifestation of FOSMN and might involve the solitary nucleus.

Acetylcholine receptor binding antibody-associated myasthenia gravis and rhabdomyolysis induced by nivolumab in a patient with melanoma.

We reported an 81-year-old woman with metastatic melanoma, in whom myasthenia gravis and rhabdomyolysis developed after nivolumab monotherapy. The first symptom of myasthenia gravis was dyspnea. Ultrasonography detected hypokinesis of the bilateral diaphragm suggesting myasthenia gravis, although there was no abnormal finding of the lungs in computed tomography images. Acetylcholine receptor binding antibodies were low-titer positive in the preserved serum before administration of nivolumab, strongly suggesting that the myasthenia gravis was a nivolumab-related immune adverse event. Despite the remarkable clinical benefits of immune checkpoint inhibitors for patients with advanced melanoma, it is important to recognize unexpected immune-related adverse events.

Autoimmune Glial Fibrillary Acidic Protein Astrocytopathy Following SARS-CoV-2 Infection.

We herein report the first case of autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy after coronavirus disease 2019 (COVID-19). A 23-year-old man experienced fatigue, a fever, and headache 14 days after the resolution of COVID-19. He was severely disoriented and admitted to our hospital. On admission, the patient exhibited disorientation, headache, neck stiffness, myoclonus of both upper limbs, dysuria, and pyramidal signs. A blood examination revealed hyponatremia, and a cerebrospinal fluid (CSF) analysis showed lymphocytic pleocytosis. The CSF test results were positive for anti-GFAPα antibodies. The patient was treated with methylprednisolone pulse therapy, followed by oral prednisolone, which quickly ameliorated his neurological abnormalities.

Spinal intradural pseudocyst formation in central nervous system superficial siderosis.

The figure shows tissue samples taken from three previous cases, revealing the cause of hemosiderin deposition in the central nervous system because of superficial siderosis.

Neurofilament light chain as a biomarker for hereditary ATTR amyloidosis - correlation between neurofilament light chain and nerve conduction study.

BACKGROUND: Neurofilament light chain (NfL) is a biomarker of neuronal injury in hereditary ATTR (ATTRv) amyloidosis. However, the correlation between NfL and nerve conduction study (NCS), the standard test for ATTRv neuropathy, has not been investigated. OBJECTIVE: Elucidate the correlation between NfL and NCS parameters. METHODS: 227 serum NfL measurements were performed in 45 ATTRv patients, 5 asymptomatic carriers, and 12 controls. Among them, 177 simultaneous analyses of NCS and NfL were conducted in 45 ATTRv patients. RESULTS: NfL levels of symptomatic patients were significantly higher than those of asymptomatic carriers and controls. Serum NfL levels were correlated with NCS parameters, especially compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) amplitudes, indicators of axonal damage. CMAP and/or SNAP amplitudes were undetectable in 9 patients (no-amplitude group) due to advanced neuropathy. NfL levels in the no-amplitude group were significantly higher than those in patients with detectable CMAP/SNAP. NfL levels significantly decreased with patisiran, although no significant changes were observed in CMAP and SNAP. CONCLUSIONS: NfL levels are found to be correlated with CMAP/SNAP amplitudes. Compared with NCS, NfL can be a more sensitive biomarker for detecting treatment response and active nerve damage even in patients with advanced neuropathy.

Auditory Neuropathy Spectrum Disorder Progressing with Motor and Sensory Neuropathy Caused by an ATP1A1 Variant.

We encountered a 27-year-old Japanese woman with sensorineural deafness progressing to motor and sensory neuropathy. At 16 years old, she had developed weakness in her lower extremities and hearing impairment, which gradually deteriorated. At 22 years old, combined audiological, electrophysiological, and radiological examination results were consistent with auditory neuropathy spectrum disorder (ANSD). Genetic analyses identified a previously reported missense variant in the ATP1A1 gene (NM_000701.8:c.1799C>G, p.Pro600Arg). Although sensorineural deafness has been reported as a clinical manifestation of ATP1A1-related disorders, our case suggested that ANSD may underlie the pathogenesis of deafness in ATP1A1-related disorders. This case report broadens the genotype-phenotype spectrum of ATP1A1-related disorders.

Functional evaluation of novel variants of B4GALNT1 in a patient with hereditary spastic paraplegia and the general population.

Hereditary spastic paraplegia (HSP) is a heterogeneous group of neurological disorders that are characterized by progressive spasticity and weakness in the lower limbs. SPG26 is a complicated form of HSP, which includes not only weakness in the lower limbs, but also cognitive impairment, developmental delay, cerebellar ataxia, dysarthria, and peripheral neuropathy, and is caused by biallelic mutations in the B4GALNT1 (beta-1,4-N-acetylgalactosaminyltransferase 1) gene. The B4GALNT1 gene encodes ganglioside GM2/GD2 synthase (GM2S), which catalyzes the transfer of N-acetylgalactosamine to lactosylceramide, GM3, and GD3 to generate GA2, GM2, and GD2, respectively. The present study attempted to characterize a novel B4GALNT1 variant (NM_001478.5:c.937G>A p.Asp313Asn) detected in a patient with progressive multi-system neurodegeneration as well as deleterious variants found in the general population in Japan. Peripheral blood T cells from our patient lacked the ability for activation-induced ganglioside expression assessed by cell surface cholera toxin binding. Structural predictions suggested that the amino acid substitution, p.Asp313Asn, impaired binding to the donor substrate UDP-GalNAc. An in vitro enzyme assay demonstrated that the variant protein did not exhibit GM2S activity, leading to the diagnosis of HSP26. This is the first case diagnosed with SPG26 in Japan. We then extracted 10 novel missense variants of B4GALNT1 from the whole-genome reference panel jMorp (8.3KJPN) of the Tohoku medical megabank organization, which were predicted to be deleterious by Polyphen-2 and SIFT programs. We performed a functional evaluation of these variants and demonstrated that many showed perturbed subcellular localization. Five of these variants exhibited no or significantly decreased GM2S activity with less than 10% activity of the wild-type protein, indicating that they are carrier variants for HSP26. These results provide the basis for molecular analyses of B4GALNT1 variants present in the Japanese population and will help improve the molecular diagnosis of patients suspected of having HSP.

Long-term Observation of a Japanese Patient with a Multiple-system Neurodegenerative Disorder with a Uniallelic de novo Missense Variant in KIF1A.

We encountered a 37-year-old Japanese man with KIF1A-associated neurological disorder (KAND) who exhibited motor developmental delay, intellectual disability, and slowly progressive cerebellar ataxia, hypotonia, and optic neuropathy. Pyramidal tract signs were evident late in this case. At 30 years old, the patient developed a neurogenic bladder. A molecular diagnosis revealed a uniallelic missense de novo variant (p.L278P) of KIF1A. Serial neuroradiological studies revealed atrophy of the cerebellum at an early age, and cerebral hemisphere atrophy progressed slowly over a 22-year observation period. Our study suggests that the primary etiology of KAND may be acquired, long-standing neurodegeneration rather than congenital hypoplasia.

Prepulse inhibition of auditory change-related cortical responses.

BACKGROUND: Prepulse inhibition (PPI) of the startle response is an important tool to investigate the biology of schizophrenia. PPI is usually observed by use of a startle reflex such as blinking following an intense sound. A similar phenomenon has not been reported for cortical responses. RESULTS: In 12 healthy subjects, change-related cortical activity in response to an abrupt increase of sound pressure by 5 dB above the background of 65 dB SPL (test stimulus) was measured using magnetoencephalography. The test stimulus evoked a clear cortical response peaking at around 130 ms (Change-N1m). In Experiment 1, effects of the intensity of a prepulse (0.5 ~ 5 dB) on the test response were examined using a paired stimulation paradigm. In Experiment 2, effects of the interval between the prepulse and test stimulus were examined using interstimulus intervals (ISIs) of 50 ~ 350 ms. When the test stimulus was preceded by the prepulse, the Change-N1m was more strongly inhibited by a stronger prepulse (Experiment 1) and a shorter ISI prepulse (Experiment 2). In addition, the amplitude of the test Change-N1m correlated positively with both the amplitude of the prepulse-evoked response and the degree of inhibition, suggesting that subjects who are more sensitive to the auditory change are more strongly inhibited by the prepulse. CONCLUSIONS: Since Change-N1m is easy to measure and control, it would be a valuable tool to investigate mechanisms of sensory gating or the biology of certain mental diseases such as schizophrenia.

Reversible Leukoencephalopathy in a Man with Childhood-onset Hyperornithinemia-Hyperammonemia-Homocitrullinuria Syndrome.

A 49-year-old Japanese man had shown developmental delay, learning difficulties, epilepsy, and slowly progressive gait disturbance in elementary school. At 46 years old, he experienced repeated drowsiness with or without generalized convulsions, and hyperammonemia was detected. Brain magnetic resonance imaging detected multiple cerebral white matter lesions. An electroencephalogram showed diffuse slow basic activities with 2- to 3-Hz δ waves. Genetic tests confirmed a diagnosis of hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome. Leukoencephalopathy was resolved following the administration of L-arginine and lactulose with a decrease in plasma ammonia levels and glutamine-glutamate peak on magnetic resonance spectroscopy. Leukoencephalopathy in HHH syndrome may be reversible with the resolution of hyperammonemia-induced glutamine toxicity.

Delayed Detection of Hydrocephalus following Mildly Traumatic Subarachnoid Hemorrhage in Corticobasal Degeneration: A Case Report.

A 65-year-old woman presented with slowly progressive aphasia with gait disturbance associated with parkinsonism. She experienced a fall that resulted in a brain trauma. Brain imaging revealed a small amount of subarachnoid hemorrhage (SAH) with intraventricular bleeding. Despite conservative therapy, gait disturbance and hyporesponsiveness gradually deteriorated following that brain trauma. One month later, she was transferred to our hospital, and magnetic resonance imaging revealed prominent communicating hydrocephalus. A ventriculoperitoneal shunt and brain biopsy were performed. Neurosurgical intervention did not improve the patient's neurological condition. Clinical-pathological analysis confirmed the diagnosis of corticobasal degeneration (CBD) as an underlying disease relating to parkinsonism and aphasia. In patients with parkinsonism with high risks of falling, attention should be paid to neurological deterioration due to traumatic SAH-related hydrocephalus. Particularly, in patients with aphasia such as in those with CBD, delayed detection of posttraumatic complications might cause poor responsiveness to surgical intervention.

Rapid and comprehensive diagnostic method for repeat expansion diseases using nanopore sequencing.

We developed a diagnostic method for repeat expansion diseases using a long-read sequencer to improve currently available, low throughput diagnostic methods. We employed the real-time target enrichment system of the nanopore GridION sequencer using the adaptive sampling option, in which software-based target assignment is available without prior sample enrichment, and built an analysis pipeline that prioritized the disease-causing loci. Twenty-two patients with various neurological and neuromuscular diseases, including 12 with genetically diagnosed repeat expansion diseases and 10 manifesting cerebellar ataxia, but without genetic diagnosis, were analyzed. We first sequenced the 12 molecularly diagnosed patients and accurately confirmed expanded repeats in all with uniform depth of coverage across the loci. Next, we applied our method and a conventional method to 10 molecularly undiagnosed patients. Our method corrected inaccurate diagnoses of two patients by the conventional method. Our method is superior to conventional diagnostic methods in terms of speed, accuracy, and comprehensiveness.

Alteration of BAFF and APRIL in the cerebrospinal fluid based on the therapeutic response in primary central nervous system B-cell lymphoma.

We evaluated the cerebrospinal fluid (CSF) levels of the B-cell activating factor of the tumor necrosis factor family (BAFF) and A proliferation-inducing ligand (APRIL) in two cases of primary central nervous system B-cell lymphoma (PCNSBL) before and after treatment. One patient achieved clinical remission, and demonstrated decrease in the CSF levels of both BAFF and APRIL after treatment. Meanwhile, the other patient with insufficient therapeutic response showed increase in the BAFF levels despite decrease in APRIL levels. This report suggests that the combination of BAFF and APRIL levels could be useful in estimating the therapeutic efficacy in treating PCNSBL as reliable CSF markers.

An Elderly Case of Paraneoplastic Anti-NMDA Receptor Encephalitis Associated with Small-cell Lung Cancer Expressing NR1 Subunits.

A 61-year-old Japanese man presented with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis. NR1 antibodies were detected in his cerebrospinal fluid. Chest computed tomography revealed lung tumor. The patient was diagnosed with paraneoplastic anti-NMDAR encephalitis associated with lung cancer and treated with two cycles of intravenous high-dose methylprednisolone and one cycle of intravenous immunoglobulin. However, he died one year later without improvement. An autopsy confirmed small-cell lung cancer (SCLC). Immunohistochemistry revealed the expression of NR1 subunits in the tumor cells, suggesting that SCLC may trigger NR1 autoimmunity though the expression of NR1 subunits as onconeural antigens, expanding the phenotypic spectrum of paraneoplastic neurological syndrome associated with SCLC.

Electrophysiological demyelinating features in hereditary ATTR amyloidosis.

OBJECTIVE: To elucidate the electrophysiological demyelinating features in patients with hereditary ATTR amyloidosis that may lead to a misdiagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP). METHODS: In 102 patients with hereditary ATTR amyloidosis (85 Val30Met and 17 non-Val30Met; 37 and 65 from endemic and non-endemic areas, respectively), results of motor nerve conduction studies (MNCSs) with a 2-Hz low-cut filter in the unilateral ulnar and tibial nerves were retrospectively investigated to assess whether each MNCS parameter demonstrated demyelinating features that fulfil the European Federation of Neurological Societies/Peripheral Nerve Society electrodiagnostic (EFNS/PNS EDX) criteria for CIDP. RESULTS: Thirteen patients with low compound muscle action potential (CMAP) amplitude in the tibial nerve (0.7 ± 0.7 mV) and prolonged distal CMAP duration in the ulnar nerve satisfied the definite EFNS/PNS EDX criteria for CIDP. Abnormal temporal dispersion and prolongation of distal latency in the tibial nerve were observed in 5 of 13 patients. However, only one of the 13 patients presented with the reduction of motor conduction velocity in each nerve. No patient exhibited conduction block in any nerve. CONCLUSION: Patients with hereditary ATTR amyloidosis occasionally show electrophysiological demyelinating features without conduction block following severe axonal degeneration.

Length-dependent truncal Aδ-fiber dysfunction in hereditary transthyretin amyloidosis: An intra-epidermal electrical stimulation study.

OBJECTIVE: To elucidate Aδ-fiber dysfunction at the trunk in patients with hereditary transthyretin (ATTRm) amyloidosis using intra-epidermal electrical stimulation (IES). METHODS: In 16 patients with ATTRm amyloidosis and 18 healthy subjects, sensory thresholds using IES and cooling detection thresholds using the Computer-Aided Sensory Evaluation (CASE IV) system, were assessed to investigate Aδ-fiber functions at the Th10 level of the anterior, lateral, and posterior trunk. Furthermore, evoked potentials (EPs) following electrical stimulation using IES at the anterior and posterior trunk were evaluated. RESULTS: In patients with ATTRm amyloidosis, both IES and CASE IV sensory thresholds tended to be higher at the anterior trunk than at the lateral and posterior trunks. The amplitudes of EPs following electrical stimulation at the anterior trunk were lower than those at the posterior trunk. Aδ-fiber dysfunction at the anterior trunk was conspicuous in patients with more intense polyneuropathy at the limbs. In healthy subjects, there were no differences in both sensory thresholds and EP amplitudes among any examination sites. Sensory thresholds with IES and CASE IV were correlated. CONCLUSIONS: Evaluation using IES demonstrated length-dependent Aδ-fiber dysfunction at the trunk in patients with ATTRm amyloidosis. SIGNIFICANCE: IES may be a useful clinical tool for investigating Aδ-fiber dysfunction at various parts of the body in patients with neuropathy.