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Background@#and Purpose Advances in serological tests are transforming the classification of idiopathic inflammatory myopathy (IIM). The new criteria suggested by the 119th European Neuromuscular Center international workshop divide IIM cases into four main diseases according to clinical and pathological findings, adding immune-mediated necrotizing myositis and nonspecific myositis to the classic categories of polymyositis and dermatomyositis. @*Methods@#Seventy one cases of IIM with sufficient available clinical and pathological data were reviewed to be reclassified according to the new criteria. @*Results@#Most of the cases previously classified as polymyositis (77.8%, 35/45) were reclassified as immune-mediated necrotizing myopathy. The results of myositis-specific antibodies matched well with the new clinicopathological classification. @*Conclusions@#This new clinicopathological classification for IIM in combination with serological test results could be applied to our previous case series. Adoption of the new criteria will lead to a better understanding of the disease and hence new therapeutic insights.
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Inclusion body myositis is a rare condition of idiopathic inflammatory myopathy. Prior criteria for the diagnosis of inclusion body myositis essentially required pathological features of rimmed vacuoles, tubulofilamentous inclusions, and amyloid deposits. However, recently developed new diagnostic criteria emphasize clinical characteristics including weakness of finger flexors and knee extensors. In addition, a serological evaluation of anti-cN1A antibody is helpful for the diagnosis. We report a case of inclusion body myositis with clinical, pathological, and serological consideration.
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Muscle and nerve biopsy may be vital diagnostic tools in various neuromuscular disorders. Since these procedures are invasive, it matters to decide when to perform a biopsy, which muscle or nerve to be selected, and how to interpret the pathologies. This review addresses the indications, methods of biopsies, and also significant pathological findings frequently encountered in muscle and nerve pathology.
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Muscle pathology can give much information to reach the diagnosis of neuromuscular disorders. Major pathological changes occurred in skeletal muscles include muscle fiber atrophy/hypertrophy, necrosis/regeneration, inflammation, myofibrillar disorganization, abnormal inclusions, and disruptions in cellular organelles. Physicians should be able to understand what each of these findings indicates. However, these are not always specific to a certain disease, and instead most of them are commonly found in many of muscle diseases. Thus, muscle pathological findings should be carefully interpreted under the given clinical settings.
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A 49-year-old man developed recurrent myalgia and hyperCKemia during acute attacks of neuromyelitis optica. Muscle biopsy was performed, and the pathological findings were analyzed. Predominant myofibrillar pathology was observed, which constitutes a unique finding that has not been reported before. This case result shows that neuromyelitis optica-associated hyperCKemia can produce variable pathologic phenotypes. Further studies are needed to elucidate the relationship between myofibril destruction and aquaporin 4 autoimmunity.
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Background@#Pompe disease is a rare autosomal recessive disorder caused by the deficiency of a lysosomal enzyme, acid alpha-glucosidase (GAA). Early diagnosis and initiation of treatment with enzyme replacement therapy have remarkable effects on the prognosis of Pompe disease. We performed the expanded screening for late onset Pompe disease (LOPD) at eight centers in Korea. @*Methods@#From September 1, 2015, GAA activity were measured from both dried blood spot (DBS) and mixed leukocyte for 188 available patients. For 12 patients with low GAA activity, we performed Sanger sequencing of GAA gene. @*Results@#Among 188 patients, 115 were males. The mean of age of symptom onset and diagnosis were 34.3 years and 41.6 years. Among 12 patients with decreased GAA activity, two patients were confirmed to have LOPD with genetic test (c.1316T>A [p.M439K] + c.2015G>A [p.R672Q], c.1857C>G [p.S619R] + c.546G>C [leaky splicing]). Other two patients had homozygous G576S and E689K mutation, known as pseudodeficiency allele. @*Conclusions@#This study is expanded study of LOPD screening for targeted Korean population. We found two patients with LOPD, and the detection rate of LOPD is 1.06%. With application of modified GAA cutoff value (0.4), which was previously reported, there were no false positive results of GAA activity test using DBS. Therefore, it could be an appropriate screening test for LOPD in especially East-Asian population, in which pseudodeficiency allele is frequent.
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Background@#Pompe disease is a rare autosomal recessive disorder caused by the deficiency of a lysosomal enzyme, acid alpha-glucosidase (GAA). Early diagnosis and initiation of treatment with enzyme replacement therapy have remarkable effects on the prognosis of Pompe disease. We performed the expanded screening for late onset Pompe disease (LOPD) at eight centers in Korea. @*Methods@#From September 1, 2015, GAA activity were measured from both dried blood spot (DBS) and mixed leukocyte for 188 available patients. For 12 patients with low GAA activity, we performed Sanger sequencing of GAA gene. @*Results@#Among 188 patients, 115 were males. The mean of age of symptom onset and diagnosis were 34.3 years and 41.6 years. Among 12 patients with decreased GAA activity, two patients were confirmed to have LOPD with genetic test (c.1316T>A [p.M439K] + c.2015G>A [p.R672Q], c.1857C>G [p.S619R] + c.546G>C [leaky splicing]). Other two patients had homozygous G576S and E689K mutation, known as pseudodeficiency allele. @*Conclusions@#This study is expanded study of LOPD screening for targeted Korean population. We found two patients with LOPD, and the detection rate of LOPD is 1.06%. With application of modified GAA cutoff value (0.4), which was previously reported, there were no false positive results of GAA activity test using DBS. Therefore, it could be an appropriate screening test for LOPD in especially East-Asian population, in which pseudodeficiency allele is frequent.
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Hereditary myopathy with early respiratory failure (HMERF) is characterized by early respiratory insufficiency which is inappropriate to the degree of limb muscle weakness. Recently, mutation in TTN gene was found in HMERF patients with the aid of gene sequencing. We describe the first case presenting with distal leg weakness and early respiratory failure confirmed by TTN gene mutation in Korea.
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BACKGROUND AND PURPOSE: GNE myopathy is a rare progressive myopathy caused by biallelic mutations in the GNE gene, and frequently accompanied by rimmed vacuoles in muscle pathology. The initial symptom of foot drop or hip-girdle weakness eventually spreads to all limbs over a period of decades. Recent advances in pathophysiologic research have facilitated therapeutic trials aimed at resolving the core biochemical defect. However, there remains unsettled heterogeneity in its natural course, which confounds the analysis of therapeutic outcomes. We performed the first large-scale study of Korean patients with GNE myopathy. METHODS: We gathered the genetic and clinical profiles of 44 Korean patients with genetically confirmed GNE myopathy. The clinical progression was estimated retrospectively based on a patient-reported questionnaire on the status of the functional joint sets and daily activities. RESULTS: The wrist and neck were the last joints to lose antigravity functionality irrespective of whether the weakness started from the ankle or hip. Two-thirds of the patients could walk either independently or with an aid. The order of losing daily activities could be sorted from standing to eating. Patients with limb-girdle phenotype showed an earlier age at onset than those with foot-drop onset. Patients with biallelic kinase domain mutations tended to progress more rapidly than those with epimerase and kinase domain mutations. CONCLUSIONS: The reported data can guide the clinical management of GNE myopathy, as well as provide perspective to help the development of clinical trials.