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Introduction/aims Immune-mediated necrotizing myopathy (IMNM) is an immune-mediated myopathy typically presenting with progressive subacute weakness and characteristic, but nonspecific, myopathological findings. Atypical cases however can mimic other inherited or acquired myopathies, depriving patients of treatment. We describe a cohort of such patients. Methods We retrospectively identified IMNM patients who either previously carried a diagnosis of an inherited myopathy established on clinicopathological grounds or whose muscle biopsies displayed atypical features suggestive of a different myopathy. Results Among 131 IMNM patients, seven previously unreported patients (5%) met one of the above criteria. Three patients were diagnosed with limb-girdle muscular dystrophy on the basis of a chronic progressive course of weakness and family history of myopathy or cardiomyopathy. The other four patients displayed atypical histological features (two prominent mitochondrial abnormalities, one myofibrillar pathology, and one granulomatous inflammation). Immunostaining of biopsies from 12 additional IMNM patients did not identify myofibrillar pathology. The patient with granulomatous inflammation was known to have pulmonary sarcoidosis. Genetic testing for inherited myopathies was unrevealing. Antibodies against 3-hydroxy-3-methylglutaryl-CoA reductase or signal recognition particle were identified in 5 and 1 patients, respectively. Four patients presented with slowly progressive weakness over 3-13 y, while weakness was subacute over ≤6 mo in three patients. All patients responded to immunomodulatory therapy. Discussion Atypical clinical and histological features can occur in IMNM patients, causing delays in diagnosis and treatment. Clinicians should, therefore, consider IMNM in the differential diagnosis of unexplained proximal myopathies in spite of atypical clinical and myopathological findings.

Objective To evaluate survival and associated comorbidities in inclusion body myositis (IBM) in a population-based, case-control study. Methods We utilized the expanded Rochester Epidemiology Project medical records-linkage system, including 27 counties in Minnesota and Wisconsin, to identify patients with IBM, other inflammatory myopathies (IIM), and age/sex-matched population-controls. We compared the frequency of various comorbidities and survival among groups. Results We identified 50 IBM patients, 65 IIM controls and 294 population controls. Dysphagia was most common in IBM (64%) patients. The frequency of neurodegenerative disorders (dementia/parkinsonism) and solid cancers was not different between groups. Rheumatoid arthritis was the most common rheumatic disease in all groups. A total of 36% of IBM patients had a peripheral neuropathy, 6% had Sjögren’s syndrome and 10% had a haematologic malignancy. T-cell large granular lymphocytic leukaemia was only observed in the IBM group. None of the IBM patients had hepatitis B or C, or HIV. IBM patients were 2.7 times more likely to have peripheral neuropathy, 6.2 times more likely to have Sjögren’s syndrome and 3.9 times more likely to have a haematologic malignancy than population controls. IBM was associated with increased mortality, with a 10-year survival of 36% from index, compared with 67% in IIM and 59% in population controls. Respiratory failure or pneumonia (44%) was the most common cause of death. Conclusions IBM is associated with lower survival, and higher frequency of peripheral neuropathy, Sjögren’s syndrome and haematologic malignancies than the general population. Close monitoring of IBM-related complications is warranted.

Introduction/aims Intracellular congophilic inclusions within muscle fibers, although nonspecific, are one of the pathological hallmarks of sporadic inclusion body myositis (sIBM). Extracellular amyloid deposits in muscle, on the other hand, are the canonical findings of amyloid myopathies, which occur with or without systemic amyloidosis. Methods We reviewed the muscle biopsy database (1998-2020) to identify sIBM patients with extracellular amyloid deposits. Clinical and laboratory data were reviewed. Results We identified five sIBM patients (three clinicopathologically defined and two clinically defined) with extracellular amyloid deposits in muscle. Mean age at diagnosis was 74.8 y (range, 68-84 y). All patients had a typical sIBM pattern of weakness without associated sensory or autonomic symptoms. None had electrophysiological evidence of peripheral neuropathy. Only one patient had a monoclonal gammopathy (immunoglobulin M-lambda, IgM-λ) with normal bone marrow biopsy. This patient with monoclonal gammopathy and three other patients underwent abdominal fat pad aspirate and were negative for amyloid. Cardiac evaluation was unrevealing in the four patients tested. Three patients without monoclonal gammopathy had normal transthyretin gene sequencing and inconclusive mass spectrometry-based analysis. The patient with monoclonal gammopathy died of pneumosepsis 5 y after diagnosis and autopsy revealed multi-organ transthyretin amyloidosis. Discussion Detection of extracellular amyloid deposition in muscle should trigger an aggressive search for systemic amyloidosis independently from other associated myopathological abnormalities. Amyloid subtyping is crucial for early therapy and mortality prevention. An isolated monoclonal gammopathy should not halt a search for non-hematological causes of systemic amyloidosis.

Ranolazine is an anti-ischemic drug often used along with statins in patients with ischemic heart disease. Ranolazine-induced proximal myopathy or rhabdomyolysis have been rarely reported, but toxic effects of statins could not be completely ruled out in those cases. We report a 68-year-old man with ranolazine-induced myopathy who presented with respiratory insufficiency and head drop. Creatine kinase level was normal. The Patient continued to worsen despite statin cessation but markedly improved after stopping ranolazine. Muscle biopsy showed excessive lipid accumulation predominantly in type 1 myofibers. The precise mechanism of toxicity is not clear. Treating physicians should be aware of this rare but potentially debilitating adverse effect of ranolazine. Prognosis is good upon discontinuation of the offending drug.

ObjectivesTo determine the prevalence and natural history of sporadic inclusion body myositis (sIBM) and to test the hypothesis that patients with sIBM have higher cancer or mortality rates than the general population.MethodsWe sought patients with sIBM defined by the 2011 European Neuromuscular Centre (ENMC) diagnostic criteria among Olmsted County, Minnesota, residents in 40-year time period.ResultsWe identified 20 patients (10 clinicopathologically defined, 9 clinically defined, and 1 probable) according to the ENMC criteria and 1 patient with all features of clinicopathologically defined sIBM except for symptom onset at p = 0.24). Two-thirds of patients developed dysphagia, and half required a feeding tube. Nine patients required a wheelchair. The median time from symptom onset to wheelchair dependence was 10.5 (range 1–29) years. Overall life expectancy was shorter in the sIBM group compared to the general population (84.1 [95% CI 78–88.4] vs 87.5 [95% CI 85.2–89.5] years, p = 0.03). Thirteen patients died; 9 deaths were sIBM related (7 respiratory and 2 unspecified sIBM complications). Female sex (p = 0.03) and dysphagia (p = 0.05) were independent predictors of death.ConclusionOlmsted County has the highest prevalence of sIBM reported to date. Patients with sIBM have similar risk of cancer, but slightly shorter life expectancy compared to matched patients without sIBM.Classification of EvidenceThis study provides Class II evidence that patients with sIBM have similar risks of cancers and slightly shorter life expectancy compared to controls.

ObjectiveTo improve myasthenia gravis (MG) autoantibody testing.MethodsMG serologic tests with confirmatory or refuting clinical–electrodiagnostic (EDX) testing and cancer evaluations were reviewed over 4 years (2012–2015). All patients had acetylcholine receptor–binding (AChR-Bi), modulating (AChR-Mo), and striational (STR) autoantibody testing, and negatives reflexed to muscle-specific kinase (MuSK). Thymoma and cancer occurrences were correlated with STR and reflexed glutamic acid decarboxylase 65 (GAD65), ganglionic acetylcholine receptor (α3), collapsin response mediating protein-5, and voltage-gated potassium channel complex autoantibodies.ResultsOf 433 samples tested, 133 (31%) met clinical–EDX criteria for MG. Best sensitivity (90%) occurred at AChR-Bi >0.02 nmol/L, leaving 14 negative (6 ocular MG, 7 generalized MG, 1 MuSK MG) with specificity 90% (31 false-positives). Using AChR-Mo antibodies (>20% loss), specificity was better (92%, 24 false-positives), but sensitivity dropped (85%). Specificity improved (95%) by testing AChR-Mo when AChR-Bi are positive, resulting in 45% reduction of false-positives (31–17), maintaining AChR-Bi 90% sensitivity. Cutoff values recommended by area under the curve analysis did not outperform this approach. AChR-Bi and AChR-Mo values were significantly higher in true-positives. CT evaluations in 121 MG samples revealed 16 thymomas. Historical or subsequent cancers occurred in 22. STR and reflexed autoantibodies were not more common in MG with thymoma or other cancers. Full-body CT (n = 34) was performed in those with STR and reflex autoantibody positivity, but without additional cancers found.ConclusionAccuracy of MG serologic testing is improved by reflexing AChR-Bi–positive cases to AChR-Mo. STR and other reflexed cancer evaluation autoantibodies did not provide value beyond standard CT chest imaging at the time of MG diagnosis. Diagnostic certainty is informed by AChR-Bi and AChR-Mo with higher values increasing specificity.

Background Limited data exist regarding myopathies with early or prominent dysphagia. Methods A retrospective study was performed (January 2003 to August 2019) to identify myopathy patients in whom dysphagia was the initial symptom or was disproportionately severe compared with limb weakness. Results Thirty-two patients were identified. The median age at diagnosis was 65 y (range, 36-80 y). Inclusion body myositis (IBM) (n = 15), immune-mediated necrotizing myopathy (IMNM) (n = 5), and oculopharyngeal muscular dystrophy (n = 4), were the most common diagnoses. In 4 patients (3 IMNM and 1 nonspecific myositis) dysphagia evolved rapidly. At evaluation, 21 patients required diet alterations, 5 required feeding tubes, and 8 had aspiration pneumonia. Follow-up data were available for 20 patients (median, 24 mo). Eight patients received immunosuppressive therapies with improvement in 7, including 3 of 4 with rapidly progressive dysphagia. Conclusions IBM and IMNM accounted for approximately two-thirds of patients with early or prominent dysphagia at our institution. Rapidly progressive dysphagia may predict immunotherapy responsiveness.

Mutations in heat shock protein B8 were initially identified in inherited neuropathies and were more recently found to cause a predominantly distal myopathy with myofibrillar pathology and rimmed vacuoles. Rare patients also had proximal weakness. Only very few pathogenic variants have been identified in HSPB8. Disruption of the chaperone activity of heat shock protein B8 impairs chaperone-assisted selective autophagy and results in protein aggregation. We report a 23-year-old patient who presented with a 4-year history of predominantly proximal lower limb weakness due to a novel variant in HSPB8. The creatine kinase level was mildly elevated. Electrodiagnostic studies demonstrated a proximal-predominant myopathy without evidence of neuropathy, and muscle histopathology revealed rimmed vacuoles and myofibrillar protein aggregates. Whole exome sequencing identified a de novo frameshift variant in the C-terminal region of HSPB8 (c.577_580dupGTCA, p.Thr194Serfs*23). This case demonstrates that HSPB8-related disorders can present with early onset limb-girdle myopathy without associated neuropathy.

Muscle diseases consist of various disorders that primarily affect skeletal muscle, but they can also affect cardiac or smooth muscle. The disorders may be inherited or acquired. The pathophysiology, clinical manifestations, diagnostic pathways, and treatment options will vary for each disorder. This chapter reviews common acquired muscle disorders. Inflammatory myopathies are characterized by muscle weakness and inflammatory reaction in muscle, and often, but not always, are accompanied by elevated creatine kinase values. They can occur with infections, systemic inflammatory diseases, or they may be idiopathic. On the basis of clinical, histologic, and immunopathologic criteria, idiopathic inflammatory myopathies can be distinguished as dermatomyositis, polymyositis, or inclusion body myositis. When dermatomyositis or polymyositis occurs in association with a connective tissue disease, the disorder is called overlap syndrome.

A 47-year-old man with hypercholesterolemia sought care for a 4-month history of progressive, proximal upper limb weakness and myalgia, followed by dysphagia, difficulty climbing stairs, and facial rash. Discontinuation of atorvastatin was of no benefit. Neurologic examination showed moderate weakness of the neck flexor muscles, shoulder girdle muscles, and finger extensors, and mild weakness of hip flexor and ankle dorsiflexor muscles. He had a heliotrope rash and Gottron sign. Serum testing showed an increased creatine kinase level. Needle electromyography showed myopathic changes with fibrillation potentials in proximal and axial muscles. Biopsy of the deltoid demonstrated a perifascicular pathologic process, including muscle fiber atrophy, and perivascular inflammatory exudate in the perimysium. Immunocytochemical studies showed patchy loss of intramuscular capillaries, some of which had complement (C5b9) deposition, and sarcoplasmic expression of myxovirus resistance protein A, mainly in the perifascicular regions. Immunologic testing was positive for autoantibodies to nuclear matrix protein 2 and negative for 3-hydroxy-3-methylglutaryl–coenzyme A reductase antibodies. Video swallow studies showed oropharyngeal dysphagia. Pulmonary function tests indicated mildly decreased maximal respiratory pressures but normal diffusing lung capacity for carbon monoxide. The findings were consistent with a diagnosis of dermatomyositis. The patient was started on oral prednisone and azathioprine, after checking for adequate thiopurine methyltransferase activity. Liver function tests and complete blood cell count with differential were assessed to monitor for potential azathioprine toxicity. Intravenous immunoglobulin was given. Follow-up examination revealed mild weakness of the shoulder girdle muscles after immunotherapy, and normal strength and creatine kinase value while on azathioprine monotherapy. Dermatomyositis is an idiopathic inflammatory myopathy. Idiopathic inflammatory myopathy is a group of autoimmune muscle diseases that includes dermatomyositis, polymyositis, inclusion body myositis, immune-mediated necrotizing myopathy, and overlap myositis, including antisynthetase syndrome.

Granulomatous myopathies are etiologically heterogeneous myopathies, pathologically characterized by the presence of intramuscular granulomas. Treatment outcomes are variable. We aimed to identify prognostic factors of treatment outcomes in myopathies featuring non-caseating granulomas. Sixteen patients were identified (9 sarcoid myopathy, 6 inclusion body myositis, and 1 granulomatous myopathy of indeterminate cause) over a 21-year period. The median age at diagnosis was 67 years in sarcoid myopathy group, and 64 years in inclusion body myositis group. Three inclusion body myositis patients were initially diagnosed with sarcoid myopathy based on the presence of systemic features of sarcoidosis and findings on muscle biopsies, but subsequent biopsies performed because of treatment refractoriness, showed all canonical pathologic features of inclusion body myositis. We identified sarcoplasmic congophilic inclusions in 6 sarcoid myopathy patients without associated rimmed vacuoles or typical weakness pattern of inclusion body myositis. Four inclusion body myositis and 4 of 5 sarcoid myopathy patients with congophilic inclusions were refractory to immunotherapy. Our study portrays the overlapping clinical and pathological features of sarcoid myopathy and inclusion body myositis. The presence of sarcoplasmic congophilic inclusions in sarcoid myopathy may predict an unfavorable outcome of immunosuppressive therapy, but a larger prospective study is required to further validate this observation.

Background: Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common muscular dystrophies and predominantly affects facial and shoulder girdle muscles. Previous case reports and cohort studies identified minor cardiac abnormalities in FSHD patients, but their nature and frequency remain incompletely characterized.Methods: We reviewed cardiac, neurological and genetic findings of 104 patients with genetically confirmed FSHD.Results: The most common conduction abnormality was complete (7%) or incomplete (5%) right bundle branch block (RBBB). Bifascicular block, left anterior fascicular block, complete atrioventricular block, and 2:1 atrioventricular block each occurred in 1% of patients. Atrial fibrillation or flutter were seen in 5% of patients. Eight percent of patients had heart failure with reduced ejection fraction and 25% had valvular disease. The latter included aortic stenosis in 6% (severe in 4% and moderate in 2%) and moderate aortic regurgitation in 8%. Mitral valve prolapse (MVP) was present in 9% of patients without significant mitral regurgitation. There were no significant associations between structural or conduction abnormalities and age, degree of muscle weakness, or size of the 4q deletion.Conclusions: Both structural and conduction abnormalities can occur in FSHD. The most common abnormalities are benign (RBBB and MVP), but more significant cardiac involvement was also observed. The presence of cardiac abnormalities cannot be predicted from the severity of the neurological phenotype, nor from the genotype.

Amyloidosis refers to an etiologically heterogeneous group of protein misfolding diseases, pathologically characterized by extracellular amyloid fibrils producing congophillic amorphous deposits in organs and tissues, which may lead to severe organ dysfunction and mortality. Clinical presentations vary and are often nonspecific, depending on what organs or tissues are affected. In systemic amyloidosis, the peripheral nervous system is commonly affected, whereas the skeletal muscles are only rarely involved. Immunoglobulin light chain (AL) amyloidosis and hereditary transthyretin (ATTRv) amyloidosis are the most frequent types of systemic amyloidosis involving the neuromuscular system. Localized amyloidosis can occur in skeletal muscle, so-called isolated amyloid myopathy. Amyloid neuropathy typically involves small myelinated and unmyelinated sensory and autonomic nerve fibers early in the course of the disease, followed by large myelinated fiber sensory and motor deficits. The relentlessly progressive nature with motor, painful sensory and severe autonomic dysfunction, profound weight loss, and systemic features are distinct characteristics of amyloid neuropathy. Amyloid myopathy presentation differs between systemic amyloidosis and isolated amyloid myopathy. Long-standing symptoms, distal predominant myopathy, markedly elevated creatine kinase level, and lack of peripheral neuropathy or systemic features are highly suggestive of isolated amyloid myopathy. In ATTR and AL amyloidosis, early treatment correlates with favorable outcomes. Therefore, awareness of these disorders and active screening for amyloidosis in patients with neuropathy or myopathy are crucial in detecting these patients in the everyday practice of neuromuscular medicine. Herein, we review the clinical manifestations of neuromuscular amyloidosis and provide a diagnostic approach to this disorder.

Background Anti-cytosolic 5'-nucleotidase 1A (cN1A) antibodies are commonly detected in patients with sporadic inclusion body myositis (sIBM). However, their pathogenic role has not been established. Moreover, efforts toward identifying sIBM distinct clinicopathologic characteristics associated with these antibodies have yielded conflicting results. Methods We first searched for patients, seen in our clinics, tested for anti-cN1A antibodies between December 2015 and December 2019. We identified 92 patients who were diagnosed with sIBM, according to the 2011 ENMC or Griggs et al criteria. Thereafter, we reviewed and compared the clinical and investigational findings of these patients in relation to their antibody status. Results Anti-cN1A antibodies were present in 47/92 (51%) patients with sIBM. Comparison of seropositive and seronegative cohorts yielded no significant difference in clinical features, including facial weakness, oropharyngeal and respiratory involvement, or disease severity. The antibody titer did not correlate with the clinical phenotype, CK value, or presence of myotonic discharges on EMG. Anti-cN1A antibody positive patients appeared to have more frequent auto-aggressive inflammation on muscle biopsy but not as an isolated myopathological feature. Conclusions Our study showed that anti-cN1A antibody positive and negative sIBM patients have similar clinical features and disease severity. Anti-cN1A antibodies in our sIBM cohort did not correlate with any studied clinical or laboratory parameter and, therefore, were of limited value in the patient's assessment.

ObjectiveTo describe neural autoantibody profiles and outcomes in patients with neurologic autoimmunity associated with immune checkpoint inhibitor (ICI) cancer immunotherapy.MethodsIn this retrospective descriptive study, 63 patients with ICI-related neurologic autoimmunity were included: 39 seen at the Mayo Clinic Neurology Department (clinical cohort) and 24 whose serum/CSF was referred to the Mayo Clinic Neuroimmunology Laboratory for autoantibody testing. Serum/CSF samples were tested for neural-specific autoantibodies. Predictors of unfavorable outcome (residual adverse event severity grade ≥3) were explored (logistic regression).ResultsMedian age at neurologic symptom onset was 65 years (range 31–86); 40% were female. Neurologic manifestations were CNS-restricted (n = 26), neuromuscular (n = 30), combined (n = 5), or isolated retinopathy (n = 2). Neural-specific autoantibodies were common in patients with CNS involvement (7/13 [54%] in the unbiased clinical cohort) and included known or unidentified neural-restricted specificities. Only 11/31 patients with CNS manifestations had neuroendocrine malignancies typically associated with paraneoplastic autoimmunity. Small-cell lung cancer (SCLC)–predictive antibodies were seen in 3 patients with non-neuroendocrine tumors (neuronal intermediate filament immunoglobulin G [IgG] and antineuronal nuclear antibody 1 with melanoma; amphiphysin IgG with non-SCLC). A median of 10 months from onset (range, 0.5–46), 14/39 in the clinical cohort (36%) had unfavorable outcomes; their characteristics were age ≥70 years, female, CNS involvement, lung cancer, higher initial severity grade, and lack of systemic autoimmunity. By multivariate analysis, only age remained independently associated with poor outcome (p = 0.01). Four of 5 patients with preexistent neurologic autoimmunity experienced irreversible worsening after ICI.ConclusionsNeural-specific autoantibodies are not uncommon in patients with ICI-related CNS neurologic autoimmunity. Outcomes mostly depend on the pre-ICI treatment characteristics and clinical phenotype.

Muscle disorders are characterized by differential involvement of various muscle groups. Among these, weakness predominantly affecting finger flexors is an uncommon pattern, most frequently found in sporadic inclusion-body myositis. This finding is particularly significant when the full range of histopathological findings of inclusion-body myositis is not found on muscle biopsy. Prominent finger flexor weakness, however, is also observed in other myopathies. It occurs commonly in myotonic dystrophy types 1 and 2. In addition, individual reports and small case series have documented finger flexor weakness in sarcoid and amyloid myopathy, and in inherited myopathies caused by ACTA1, CRYAB, DMD, DYSF, FLNC, GAA, GNE, HNRNPDL, LAMA2, MYH7, and VCP mutations. Therefore, the finding of finger flexor weakness requires consideration of clinical, myopathological, genetic, electrodiagnostic, and sometimes muscle imaging findings to establish a diagnosis.

Delayed diagnosis of immune-mediated necrotizing myopathy leads to increased morbidity. Patients with the chronic course without 3-hydroxy-3-methylglutaryl-coenzyme-A reductase-IgG or signal recognition particle-IgG are often challenging to diagnose. Immunotherapy response can also be difficult to assess. We created a statistical model to assist immune-mediated necrotizing myopathy diagnosis. Electrical myotonia versus fibrillations were reviewed as biomarkers for immunotherapy treatment response. Identified were 119 immune-mediated necrotizing myopathy cases and 938 other myopathy patients. Inclusion criteria included all having electrophysiological evaluations, muscle biopsies showing inflammatory/necrotizing myopathies, comprehensively recorded neurological examinations, and creatine kinase values. Electrical myotonia was recorded in 56% (67/119) of retrospective and 67% (20/30) of our validation immune-mediated necrotizing myopathy cohorts, and significantly (P 86%) at the first visit. Inherited myopathies were commonly first suspected in them. Follow-up evaluation in patients with electrical myotonia on immunotherapy was available in 19 (median 21 months, range 2–124) which reduced from 36% (58/162) of muscles to 7% (8/121; P, Delayed diagnosis of immune-mediated necrotizing myopathy leads to increased morbidity. Chronic course or antibody negative status complicates diagnosis. Immunotherapy treatment response can also be difficult to assess. Triplett et al. generated a statistical model to assist immune-mediated necrotizing myopathy diagnosis demonstrating the value of electrical myotonia discovery in that model and in immunotherapy monitoring., Graphical Abstract

Distal myopathies are a group of rare muscle diseases characterized by distal weakness at onset. Although acquired myopathies can occasionally present with distal weakness, the majority of distal myopathies have a genetic etiology. Their age of onset varies from early-childhood to late-adulthood while the predominant muscle weakness can affect calf, ankle dorsiflexor, or distal upper limb muscles. A spectrum of muscle pathological changes, varying from nonspecific myopathic changes to rimmed vacuoles to myofibrillar pathology to nuclei centralization, have been noted. Likewise, the underlying molecular defect is heterogeneous. In addition, there is emerging evidence that distal myopathies can result from defective proteins encoded by genes causative of neurogenic disorders, be manifestation of multisystem proteinopathies or the result of the altered interplay between different genes. In this review, we provide an overview on the clinical, electrophysiological, pathological, and molecular aspects of distal myopathies, focusing on the most recent developments in the field. Muscle Nerve 59:283-294, 2019.

Introduction Recessive mutations in the anoctamin-5-encoding gene (ANO5) cause muscular dystrophy of various phenotypes. Intramuscular interstitial amyloid deposits were detected in a few patients with anoctaminopathy-5, some with cardiac involvement. The frequency of amyloid deposition in anoctaminopathy-5 and its impact on phenotype are unknown. Methods We retrospectively identified patients with genetically proven anoctaminopathy-5 who had undergone muscle biopsy and reviewed their clinical and laboratory data. Results Eight of 15 patients with anoctaminopathy-5 had intramuscular interstitial amyloid deposits. The median age at onset of weakness was 40 and 45 years in the amyloidosis and nonamyloidosis groups, respectively. Mutations occurred throughout the entire gene in the amyloidosis group. Atrial arrhythmia was noted in 4 patients with amyloidosis and in 4 patients without amyloidosis. The latter group also had premature ventricular contractions. One nonamyloidosis patient had septal hypokinesia. Discussion Intramuscular amyloidosis occurred in 53% of patients with anoctaminopathy-5 who underwent muscle biopsy and had no impact on the phenotype. Muscle Nerve 59:133-137, 2019.

ObjectiveTo investigate the diagnostic challenges of congenital myasthenic syndromes (CMS) in adult neuromuscular practice.MethodsWe searched the Mayo Clinic database for patients with CMS diagnosed in adulthood in the neuromuscular clinic between 2000 and 2016. Clinical, laboratory, and electrodiagnostic data were reviewed.ResultsWe identified 34 patients with CMS, 30 of whom had a molecular diagnosis (14 DOK7, 6 RAPSN, 2 LRP4, 2 COLQ, 2 slow-channel syndrome, 1 primary acetylcholine receptor deficiency, 1 AGRN, 1 GFPT1, and 1 SCN4A). Ophthalmoparesis was often mild and present in 13 patients. Predominant limb-girdle weakness occurred in 19 patients. Two patients had only ptosis. Age at onset ranged from birth to 39 years (median 5 years). The median time from onset to diagnosis was 26 years (range 4–56 years). Thirteen patients had affected family members. Fatigable weakness was present when examined. Creatine kinase was elevated in 4 of 23 patients (range 1.2–4.2 times the upper limit of normal). Repetitive nerve stimulation revealed a decrement in 30 patients. Thirty-two patients were previously misdiagnosed with seronegative myasthenia gravis (n = 16), muscle diseases (n = 15), weakness of undetermined cause (n = 8), and others (n = 4). Fifteen patients received immunotherapy or thymectomy without benefits. Fourteen of the 25 patients receiving pyridostigmine did not improve or worsen.ConclusionMisdiagnosis occurred in 94% of the adult patients with CMS and causes a median diagnostic delay of nearly 3 decades from symptom onset. Seronegative myasthenia gravis and muscle diseases were the 2 most common misdiagnoses, which led to treatment delay and unnecessary exposure to immunotherapy, thymectomy, or muscle biopsy.

Programmed death-1 (PD-1) inhibitors are increasingly used in cancer immunotherapy. Various immune-related adverse events are reported, including infrequent individual case reports of myositis or rhabdomyolysis. The frequency and diagnostic spectrum of immune-related adverse events affecting skeletal muscle in PD-1 inhibitor-treated patients are unknown. We searched the Mayo Clinic Pharmacy database (2014-2016) to identify patients who developed myopathies during or after PD-1 inhibitor therapy. Among 654 cancer patients received PD-1 inhibitors (pembrolizumab=389; nivolumab=264; both=1), we identified 5 patients (pembrolizumab=5) with biopsy-proven myopathies (2 necrotizing myopathy, 1 early dermatomyositis, and 2 nonspecific myopathy). Four patients developed concomitant autoimmune disorders. Weakness occurred after a median of 2 treatments (range, 1-4). All patients had proximal or axial weakness. Four patients had either bulbar or extraocular weakness, but only 1 patient had acetylcholine receptor antibodies. Creatine kinase levels were elevated in 3 patients (necrotizing myopathy=2; nonspecific myopathy=1). Brain magnetic resonance imaging revealed abnormal T2 signal and enhancement of extraocular muscles in 1 patient with ophthalmoparesis. Pembrolizumab was discontinued in all patients. All patients received immunosuppressive therapy, with fatal outcome in 2 necrotizing myopathy patients and favorable outcome in others. We conclude that myopathy is a rare, but unique complication of PD-1 inhibitors with frequent involvement of extraocular or bulbar muscles, mimicking myasthenia gravis. Muscle biopsy is an important test for PD-1 inhibitor-treated patients who develop oculobulbar weakness and hyperCKemia, to distinguish patients with necrotizing myopathy from myasthenia gravis. Necrotizing myopathy patients may require more aggressive immunotherapy due to their grave prognosis.

Myofibrillar myopathy is a pathologically diagnosed myopathy encompassing a clinically and genetically heterogeneous group of myopathies that share common histopathologic features of dissolution of myofibrils, accumulation of myofibrillar degradation products, and ectopic expression of multiple proteins.1 Patients with myofibrillar myopathy present with progressive proximal or distal predominant weakness at a variable age at onset, ranging from childhood to late adulthood. Cardiomyopathy and peripheral neuropathy are frequent extramuscular manifestations. To date, mutations in more than 10 genes underlie myopathies with myofibrillar pathology, most of which encodes Z disc–associated proteins or proteins involving in chaperon-assisted selective autophagy.1

Background and purpose Amyloid myopathy frequently occurs in the setting of systemic amyloidosis and less commonly in isolation (isolated amyloid myopathy). Anoctaminopathy-5 and dysferlinopathy were recently recognized as causes of isolated amyloid myopathy. The present study aimed to characterize the isolated amyloid myopathy and to compare it with amyloid myopathy associated with systemic amyloidosis. Methods We searched the Muscle Laboratory database to identify patients with pathologically confirmed amyloid myopathy seen in neurology clinics between January 1998 and September 2016. Patients with monoclonal gammopathy, peripheral neuropathy, organomegaly or symptoms or pathologic evidence of amyloid deposition outside skeletal muscle were classified as having systemic amyloidosis-associated myopathy. Results Fifty-two patients were identified, including 14 with isolated amyloid myopathy (eight anoctaminopathy-5, two dysferlinopathy and four genetically unknown) and 38 with systemic amyloidosis (32 immunoglobulin light-chain amyloidosis, four familial amyloid polyneuropathy and two senile systemic amyloidosis). Compared with patients with systemic amyloidosis, patients with isolated amyloid myopathy had a younger age of onset (median, 41.5 vs. 65 years), no dysphagia (0% vs. 26%) or weight loss (0% vs. 26%), but more frequent calf atrophy (57% vs. 0%), small collections of inflammatory cells on muscle biopsy (43% vs. 0%) and asymptomatic hyperCKemia at onset (21% vs. 0%). All patients with isolated amyloid myopathy had creatine kinase (CK) values >2.5 times the upper limit of normal. Conclusions Isolated amyloid myopathy accounts for 27% of patients with amyloid myopathy, mostly due to anoctaminopathy-5. There are various clinical and laboratory parameters that can help to differentiate isolated amyloid myopathy from systemic amyloidosis.

A 31-year-old man presented with a 6-year history of slowly progressive calf atrophy and weakness. EMG showed distal myopathy with fibrillation potentials. Creatine kinase (CK) was 2,848 U/L (normal T and novel c.145-1G>A variants in the dysferlin gene ( DYSF ). Intramuscular interstitial amyloid deposits can occur in systemic amyloidosis (AL or ATTR)1 or less commonly in muscular dystrophies ( DYSF and ANO5 ).2 Longstanding symptoms, young age at onset, calf atrophy, markedly elevated CK, and lack of systemic involvement are suggestive of muscular dystrophies.2

We describe a 70 year-old independently ambulatory man with a 10-year history of progressive axial and limb-girdle weakness, hyperCKemia, and a 5-year history of dyspnea requiring nocturnal ventilatory support due to a known c.1309C>T (p.Arg437Cys) variant and a novel in-frame deletion of exons 17–19 in the calpain-3 encoding gene (CAPN3). Pulmonary function tests revealed neuromuscular respiratory weakness. Biceps femoris biopsy showed chronic myopathic changes, numerous lobulated fibers, and reduced calpain-3 immunoreactivity. Muscle immunoblot showed markedly reduced calpain-3 expression. Respiratory insufficiency is uncommon in autosomal recessive calpainopathy, and generally develops in the advanced stages of the disease when individuals become wheelchair-dependent. Our patient broadens the phenotypic spectrum of recessive calpainopathy to include early respiratory insufficiency and also further expands its molecular spectrum.

Objective To characterize the cardiorespiratory abnormalities in patients with necrotizing autoimmune myopathy (NAM). Patients and Methods Cardiopulmonary features of patients with NAM evaluated in our neuromuscular clinic (January 1, 2004, to September 20, 2018) were reviewed retrospectively with respect to autoantibody status and history of cardiac disease. Clinical characteristics and laboratory findings were compared among patient subgroups. Results We identified 109 patients with NAM: 36 anti–3-hydroxy-3-methylglutaryl coenzyme A reductase autoantibody (anti-HMGCR Ab)–positive, 18 anti–signal recognition particle antibody (anti-SRP Ab)–positive (3 dual anti-HMGCR/anti–SRP Ab–positive), and 58 seronegative. Median age at diagnosis was 60 years (range, 18-86 years). Forty-three patients had dyspnea at presentation and 32 patients had preexisting risk for cardiac disease (10 coronary artery disease and 28 hypertension). The electrocardiogram was abnormal in 55 of 86 patients (33 without cardiac risk factors), including prolonged corrected QT interval (QTc) (n=31), conduction blocks (n=19), and atrial or ventricular ectopic beats (n=10). Echocardiography was abnormal in 34 of 72 patients, including 19 of 45 without preexisting cardiac disease risks. Echocardiographic abnormalities included left ventricular diastolic dysfunction (n=31) and systolic dysfunction (n=8). The left ventricular diastolic dysfunction improved in 4 of 11 patients after treatment. Pulmonary function testing showed changes suggestive of neuromuscular respiratory muscle weakness in 51 of 66 patients and reduced carbon monoxide diffusing capacity in 11 of 35 patients. However, only 6 patients had radiographic evidence of interstitial lung disease (2 anti-HMGCR Ab–positive and 4 seronegative). Overnight oximetry revealed desaturations in 24 of 38 patients. Six patients required mechanical ventilation and 7 required noninvasive ventilatory support. Conclusion Most patients with NAM exhibited cardiac and respiratory muscle dysfunction. Immunotherapy can improve echocardiographic abnormalities. Interstitial lung disease was rarely identified. Formal evaluation of cardiac and respiratory status should be integral in assessment of patients with NAM.

Introduction Although peripheral neuropathy and cardiomyopathy are well-recognized manifestations of transthyretin (ATTR) amyloidosis, myopathy has been rarely reported. Methods In this study we reviewed our muscle biopsy database (January 1998 to June 2018) to identify patients with ATTR amyloid myopathy confirmed by molecular or proteomic analysis. Clinical and laboratory findings were reviewed. Results We identified eight ATTR amyloid myopathy patients (5 hereditary ATTR [ATTRv] and 3 wild-type ATTR [ATTRwt]). Myopathy was the initial manifestation in all ATTRwt patients and followed peripheral neuropathy (4 patients) or cardiomyopathy (1 patient) in ATTRv patients. One ATTRv patient developed myopathy after liver transplant. Peripheral neuropathy and cardiac amyloidosis occurred in seven and six patients, respectively. Muscle biopsy showed interstitial amyloid deposition in all patients, rare necrotic/regenerating fibers in six, and vacuoles in four. Discussion Myopathy can be the initial manifestation of ATTRwt amyloidosis and can precede the peripheral neuropathy or occur after liver transplant in ATTRv amyloidosis.

Although myopathies and neuromuscular junction disorders are typically distinct, their coexistence has been reported in several inherited and acquired conditions. Affected individuals have variable clinical phenotypes but typically display both a decrement on repetitive nerve stimulation and myopathic findings on muscle biopsy. Inherited causes include myopathies related to mutations in BIN1, DES, DNM2, GMPPB, MTM1, or PLEC and congenital myasthenic syndromes due to mutations in ALG2, ALG14, COL13A1, DOK7, DPAGT1, or GFPT1. Additionally, a decrement due to muscle fiber inexcitability is observed in certain myotonic disorders. The identification of a defect of neuromuscular transmission in an inherited myopathy may assist in establishing a molecular diagnosis and in selecting patients who would benefit from pharmacological correction of this defect. Acquired cases meanwhile stem from the co-occurrence of myasthenia gravis or Lambert-Eaton myasthenic syndrome with an immune-mediated myopathy, which may be due to paraneoplastic disorders or exposure to immune checkpoint inhibitors.

Mutations in GMPPB cause a wide spectrum of neuromuscular syndromes, including muscular dystrophies and congenital myasthenic syndrome. The mechanisms by which GMPPB mutations impair neuromuscular transmission however remain incompletely understood. We expand here upon a previous report of one such patient presenting with a myopathy-congenital myasthenic syndrome overlap phenotype. Fatigable proximal muscle weakness developed gradually between 13 and 25 years of age, with subsequent stabilization. Low-frequency repetitive nerve stimulation showed a decrement, while a muscle biopsy demonstrated the presence of a centronuclear myopathy. Genetic testing identified a homozygous c.458C > T (p.Thr153Ile) variant in GMPPB. In-vitro microelectrode recordings and ultrastructural studies showed impairment of both pre- and postsynaptic neuromuscular transmission, thus demonstrating the presence of not only postsynaptic, but also presynaptic pathology in GMPPB-related disorders.

Actinopathy is a group of clinically and pathologically heterogeneous myopathies due to mutations in the skeletal muscle sarcomeric α-actin 1-encoding gene (ACTA1). Disease-onset spans from prenatal life to adulthood and weakness can preferentially affect proximal or distal muscles. Myopathological findings include a spectrum of structural abnormalities with nemaline rods being the most common. We report a daughter and father with prominent finger flexors and/or quadriceps involvement. Muscle biopsies revealed rimmed vacuoles in both patients, associated with type 1 fiber atrophy in the daughter, and nemaline rods in the father. Next generation sequencing identified a novel dominant ACTA1 variant, c.149G > A (p.Gly50Asp) in both individuals and no abnormal variants in vacuolar myopathy-associated genes. Our findings expand the clinico-pathological spectrum of actinopathy.

Introduction Decremental responses in repetitive nerve stimulation have been reported in a few hereditary myopathies. We examined the frequency of decrement in a cohort of myopathy patients. Methods We reviewed all patients referred for myopathy who underwent repetitive nerve stimulation between January 2007 and May 2017. We included patients with decrement (>10%) and either a pathological or molecular diagnosis of myopathy. Results Among 157 patients with myopathies, 4 patients had decrement (2 hydroxychloroquine-associated vacuolar myopathy, 1 centronuclear myopathy, and 1 distal myopathy). One hydroxychloroquine-associated vacuolar myopathy patient also had inflammatory myopathy. Pyridostigmine improved weakness in the centronuclear myopathy patient, but not in the distal myopathy patient. No patient with an acquired myopathy received pyridostigmine. Conclusions Despite the rare occurrence of decrement in myopathy, its presence may urge consideration of pharmacological intervention. Muscle Nerve 59:475-478, 2019.

Introduction: Distal acquired demyelinating symmetric (DADS) neuropathy is a distal variant of chronic inflammatory demyelinating polyradiculoneuropathy. It is characterized by chronic distal symmetric sensory or sensorimotor deficits. Sensory ataxia is a common clinical presentation. Nerve conduction studies typically show markedly prolonged distal motor latencies. Methods: We report 2 patients with chronic progressive generalized pain and fatigue, with normal neurological examinations except for allodynia. Results: Nerve conduction studies were typical of DADS neuropathy. Monoclonal protein studies were negative. Cerebrospinal fluid protein levels were elevated. Sural nerve biopsies revealed segmental demyelination and remyelination. One biopsy had marked endoneurial and epineurial lymphocytic infiltration. Immunomodulatory therapy alleviated the pain and fatigue and markedly improved distal motor latencies in both patients. Conclusions: DADS neuropathy can present with pain and a normal neurological examination apart from allodynia. Nerve conduction studies are necessary for diagnosis. These patients respond to immunotherapy better than typical DADS neuropathy patients with sensory ataxia. Muscle Nerve 54: 973–977, 2016

We read with great interest the recent article by Dr. Dieudonne et al.1 The authors reported the high prevalence of sporadic inclusion body myositis (SIBM) in patients with granulomatous myositis, and a significant proportion of these SIBM patients also had systemic features suggestive of sarcoidosis. Their observation is similar to what we previously reported.2 In addition, we found that the majority of treatment-refractory granulomatous myositis patients had sarcoplasmic congophilic deposits, including those who did not fulfill the ENMC diagnostic criteria of SIBM. Although this was not statistically significant, the presence of congophilic aggregates—regardless of the diagnosis of SIBM—could be an indicator of treatment refractoriness. Dr. Dieudonne et al. analyzed the protein accumulation using TDP43 or p62 immunoreactivity, but we are not certain whether congo red stain was performed. We would appreciate if they can share their experience with congo red stain in their cohort because this is more widely available stain in routine clinical practice when compared with TDP43 and p62 immunostains. Last but not least, given the similar results of 2 relatively large cohorts of granulomatous myositis,1,2 an epidemiologic study looking into the incidence of SIBM in sarcoidosis could be of clinical interest.

In recent years, immune checkpoint inhibitors have been increasingly used in patients with metastatic cancers with favorable oncological outcomes; however, there have also been increasing number of cancer survivors who have developed immune-related adverse events. Little is known about PD-1 inhibitor-associated neuromuscular complications. Neuromuscular disorders are the most common neurological complication reported in PD-1 inhibitor-treated patients. Myasthenia gravis, immune-mediated myopathies, and Guillain-Barre syndrome are among commonly reported immune-related neuromuscular complications. HyperCKemia occurs frequently in patients with PD-1 inhibitor-associated myasthenia gravis, indicating coexisting myopathies or myocarditis. Oculobulbar weakness is a unique and common presentation of PD-1 inhibitor-associated immune-mediated myopathies with or without concomitant myasthenia gravis. High-dose steroid monotherapy may be associated with clinical deterioration in some patients with PD-1 inhibitor-associated myasthenia gravis, immune-mediated myopathies, or Guillain-Barre syndrome. PD-1 inhibitor-associated neuromuscular complications have some characteristic features compared to their idiopathic counterparts. Although steroid monotherapy is commonly used in non-neuromuscular autoimmune disorders triggered by anti-PD-1 therapy, this may lead to unfavorable outcomes in some patients with PD-1 inhibitor-associated neuromuscular complications.

The formation of tubular aggregates (TA) within muscle fibers has been associated with toxic, metabolic, and hereditary myopathies, congenital myasthenic syndromes (CMS),1 and recently with pembrolizumab-associated myopathy.2 On electron microscopy, TA have the appearance of parallel tubules in crystalline arrangements, and are continuous extensions of the sarcotubular membrane system.1 TA have not been reported in necrotizing autoimmune myopathy associated with 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) antibodies. A 60-year-old man experienced muscle pain and cramping within 18 months of initiating statin treatment, followed by bilateral proximal lower limb and hand grip weakness that progressed over 8 months. Creatine kinase (CK) was 18,674 U/L (normal 200 units (normal < 20). The quadriceps muscle biopsy is shown in the figure. Repetitive nerve stimulation showed no decrement. Next-generation sequencing of 166 myopathy/CMS genes, including those associated with TA, demonstrated no pathogenic variants. IV immunoglobulin therapy led to clinical improvement and normalization of CK.

In the article “BOLD cerebrovascular reactivity as a novel marker for crossed cerebellar diaschisis,” Sebok et al. reported similar sensitivity of blood oxygen level–dependent cerebrovascular reactivity (BOLD-CVR) in detecting crossed cerebellar diaschisis (CCD) as compared to (15O)-H2O-PET in 25 participants with symptomatic unilateral cerebrovascular steno-occlusive disease and reported that those with CCD had poorer baseline neurologic performance and 3-month neurologic outcome. In response, Reidler et al. question whether CCD was the cause of consequence of poor outcomes, noting that it may be an epiphenomenon of large-volume supratentorial strokes and citing conflicting evidence in the literature about independent association of CCD with post-stroke outcomes. They suggest accounting for lesion volume and distribution in the analyses. In their reply, Niftrik et al. agree that their finding of worse outcome in those with CCD should be cautiously interpreted and investigated in follow-up studies, but argue that supratentorial stroke volume is an inexact measurement, although stroke location would be helpful to examine. They clarify their finding of impaired supratentorial BOLD-CVR in the group with CCD and opine that hemodynamic changes may cause CCD rather than just functional disruption.

Progressive muscular atrophy (PMA) is a rare, sporadic, adult-onset motor neuron disease, clinically characterized by isolated lower motor neuron features; however, clinically evident upper motor neuron signs may emerge in some patients. Subclinical upper motor neuron involvement is identified pathologically, radiologically, and neurophysiologically in a substantial number of patients with PMA. Patients with subclinical upper motor neuron involvement do not fulfill the revised El Escorial criteria to participate in amyotrophic lateral sclerosis clinical trials. Intravenous immunoglobulin therapy is only marginally beneficial in a small subgroup of patients with lower motor neuron syndrome without conduction block.

A 52-year-old woman presented with a 12-year history of progressive limb weakness. She first had trouble climbing stairs and later difficulty getting up from a chair. She also experienced hip and shoulder pain. Over the previous 2 years, combing her hair became difficult. She denied any eyelid drooping, double vision, chewing or swallowing difficulty, slurred speech, shortness of breath, numbness, tingling, autonomic symptoms, or cognitive problems. She did not have any rashes or joint pain. She had no other medical problems and was not taking any medications. She was born full-term and had normal developmental milestones. She was able to keep up with her peers and was a good runner during her childhood. The patient was of German descent and her father and paternal uncle developed leg weakness in their early 40s and were diagnosed with limb-girdle muscular dystrophy (LGMD). They died in a plane crash in their late 40s. The patient's older brother and her uncle's son developed leg weakness in their early 40s and were also diagnosed with LGMD. Both died in their mid-to-late 50s due to respiratory failure. Her brother also had peripheral neuropathy. The diagnosis of LGMD in all family members is based on clinical presentations and muscle biopsies. Genetic studies were not performed. There was no family history of dementia, bone disorder, or motor neuron disease. Her neurologic examination revealed symmetrical weakness of shoulder and hip girdle muscles (Medical Research Council [MRC] grade 4), as well as anterior leg compartment muscles (MRC grade 4+). She also had scapular winging bilaterally. There was no myotonia, muscle rippling, fasciculation, muscle atrophy, or hypertrophy. Deep tendon reflexes were normal except for absent ankle reflexes on both sides. Cognition, cranial nerves, sensory examination, and coordination were normal. She had high-arched feet and hammertoes. There was neither joint contracture nor spinal rigidity.

Introduction: Valosin-containing protein (VCP) is a ubiquitously expressed, multifunctional AAA-ATPase protein. Its dominant mutations cause hereditary inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia (IBMPFD) or amyotrophic lateral sclerosis. The pattern of muscle weakness in IBMPFD patients is variable and includes limb-girdle, scapuloperoneal, distal, or axial distributions. Case Report: We report a 63-year-old man with progressive scapuloperoneal weakness, head drop, and hyperCKemia since age 40 years. Electromyography showed myopathic changes and rare myotonic discharges. Muscle biopsy revealed numerous lobulated fibers, few fibers with glycogen accumulation, and rare fibers with polyglucosan bodies. Rimmed vacuoles and congophilic inclusions, often seen in IBMPFD, were absent. VCP sequencing identified a novel heterozygous c. 1160G>A mutation resulting in p.Asn387Ser substitution. Conclusions: Our patient broadens the pathological spectrum of VCP-myopathy and emphasizes the importance of VCP analysis in patients with scapuloperoneal muscular dystrophy despite the absence of Paget disease, dementia, rimmed vacuoles, or intracellular amyloid deposition. Muscle Nerve 50:295–299, 2014

Mutations in skeletal muscle α-actin 1-encoding gene (ACTA1) cause autosomal dominant or recessive myopathies with marked clinical and pathological heterogeneity. Patients typically develop generalized or limb-girdle pattern of weakness, but recently a family with scapuloperoneal myopathy was reported. We describe a father and 2 children with childhood-to-juvenile onset distal myopathy, carrying a novel dominant ACTA1 variant, c.757G>C (p.Gly253Arg). Father had delayed motor development and developed significant proximal weakness later in life; he was initially misdiagnosed as having spinal muscular atrophy based on electromyographic findings. His children had predominant anterior distal leg and finger extensor involvement. Nemaline rods were abundant on the daughter's biopsy, absent on the father's initial biopsy, and extremely rare on the father's subsequent biopsy a decade later. The father's second biopsy also showed myofibrillar pathology and rare fibers with actin filament aggregates. The present family expands the spectrum of actinopathy to include a distal myopathy.

We report a 58-year-old woman with slowly progressive facio-scapulo-peroneal muscle weakness due to congenital nemaline myopathy (NM) caused by a novel ACTA1 mutation (c.118A>G, p.Met271Val). In adult patients, congenital NM should be distinguished from sporadic late-onset nemaline myopathy (SLONM), which is a treatable acquired muscle disease often associated with monoclonal gammopathy or HIV infection. Both congenital NM and SLONM are characterized by the presence of nemaline rods in muscle. The patient's clinical history of difficulty running since childhood and weakness in other family members favored a congenital NM. The type 1 fiber atrophy and clusters of rods in normal size muscle fibers supported the diagnosis of congenital NM and prompted genetic molecular testing, which led to discovery of the novel ACTA1 variant causative of the myopathy.

Introduction: Psoriasis is a T-cell–mediated skin disorder with uncommon extracutaneous manifestations. Rare patients with psoriasis and myopathy have been reported. Methods: We conducted a retrospective review of medical records of psoriasis patients seen at the Mayo Clinic during the period from January 1, 1996 to May 31, 2011. Patients who had pathologically confirmed myopathy or lymphocytic infiltrates in muscle were included. Results: Among 11,370 psoriasis patients, 13 had pathologically confirmed myopathies. Seventy percent were inflammatory myopathies, and 2 had focal inflammation in the muscle. Psoriasis preceded myopathy onset in two-thirds of the patients (median 14.7 years). Half of the patients had psoriatic arthritis; 60% had other autoimmune disorders. Patients who received anti–tumor necrosis factor-alpha (anti–TNF-α) therapy had a higher risk for developing myopathy or inflammation in muscle (odds ratio = 4.45). Conclusions: Myopathy or inflammation in muscle affects an average of 1.32 of every 1000 psoriasis patients. Concomitant autoimmune disorders, psoriatic arthritis, and exposure to anti–TNF-α therapy may be associated with increased risk of developing myopathy in psoriasis patients. Muscle Nerve 48:716–721, 2013

Objective To characterize the natural history of immunoglobulin light chain amyloidosis–associated myopathy and to provide guidelines for recognition. Patients and Methods Fifty-one patients with systemic immunoglobulin light chain amyloidosis and biopsy-confirmed muscle amyloid deposition diagnosed between January 1, 1995, and December 31, 2015, were included in this study. Results Common presenting symptoms were muscle weakness in 49 patients (96%), dysphagia in 23 (45%), myalgia in 17 (33%), macroglossia in 17 (33%), jaw claudication in 13 (25%), and hoarseness in 9 (18%). The median time from the onset of symptoms to diagnosis was almost 2 years. Less than two-thirds of the patients with an outside muscle biopsy (16 of 27) had an established pathologic confirmation of amyloidosis due to failure to routinely incorporate Congo red staining. Moreover, 12 patients were incorrectly treated before diagnosis of amyloid myopathy. More than half of the patients had normal creatine kinase levels at diagnosis. Cardiac troponin T levels were elevated above the reference range in 5 of 12 patients who lacked evidence of cardiac involvement. Median overall survival was 32 months. Factors associated with inferior survival were involvement of more than 2 organs (median survival, 13 months), cardiac involvement (median survival, 15 months), and absence of stem cell transplant (median survival, 18 months). With the exclusion of patients treated with stem cell transplant, no improvement in survival was seen over the 1995-2004 and 2005-2015 decades. Conclusion Immunoglobulin light chain amyloidosis–associated myopathy is rare. Delay in diagnosis is common, and there is a high rate of pathologic and clinical misdiagnosis. Awareness of elevation of cardiac troponin T levels in the absence of cardiac disease may be a clue to diagnosis.

Camptocormia is a debilitating gait disorder characterized by the hyperflexion of the thoracolumbar spine during the upright position. Its etiologies are heterogenous, including parkinsonism and various neuromuscular disorders. Here, we report a camptocormia patient due to a late-onset axial myopathy with numerous lobulated fibers. The patient's father reportedly had similar symptoms. Myriad lobulated fibers are common among patients with an autosomal recessive muscular dystrophy due to calpain-3 gene (CAPN3) mutations or calpainopathy. CAPN3 sequencing revealed a single c.759-761delGAA mutation. Calpainopathy carriers are generally asymptomatic. The presence of lobulated fibers in this patient suggests that camptocormia could be a manifestation of calpainopathy carrier, although the possibility of a coexisting undiagnosed myopathy cannot be excluded. The current patient should spur the evaluation of camptocormia among calpainopathy carriers.

Introduction Rippling muscle disease (RMD) is a rare disorder of muscle hyperexcitability clinically characterized by painful muscle stiffness, rippling phenomenon, percussion-induced muscle mounding, and rapid contraction. RMD is typically considered to be electrically silent, but electrical activity during the muscle rippling has been occasionally described. RMD could be genetically determined or immune-mediated (iRMD). The association between cancer and iRMD is extremely rare. Case report We present here a patient with electrically active iRMD preceding the diagnosis of breast cancer. The patient had acetylcholine receptor binding antibodies but no clinical or electrophysiological signs of myasthenia. Muscle biopsy revealed inflammatory changes and a mosaic distribution of sarcolemmal caveolin-3 deficiency. Sequencing of caveolin-3 gene detected no mutation. Immunotherapy led to the resolution of the RMD and disappearance of the serum acetylcholine receptor antibodies. Conclusions The abnormal electrical activity in this patient suggests that an acquired neuromuscular hyperexcitability syndrome represents a continuum of disorders. The close temporal relationship between the onset of iRMD and the diagnosis of breast cancer raises the possibility that iRMD might be paraneoplastic.