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Neurology
Published in Kaji Sritharan, Jonathan Rohrer, Alexandra C Rankin, Sachi Sivananthan, Essential Notes for Medical and Surgical Finals, 2021
Kaji Sritharan, Jonathan Rohrer, Alexandra C Rankin, Sachi Sivananthan
Inherited Muscular dystrophies (e.g. Duchenne, Becker)Myotonias (e.g. myotonic dystrophy)Other congenital myopathies (lots!)
Miscellaneous Topics
Published in Nirmal Raj Gopinathan, Clinical Orthopedic Examination of a Child, 2021
Prateek Behera, Karthick Rangasamy, Nirmal Raj Gopinathan
Muscular dystrophies are rare genetic disorders seen in children.2 Myopathies can be of genetic origin, or they can be secondary to inflammatory, endocrinological, nutritional, and drug-induced causes. The muscular dystrophies that are encountered in clinical practice are Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), and congenital muscular dystrophy (CMD). Of these, DMD and BMD are seen in males (X-linked inheritance). DMD is the most common hereditary neuromuscular disease affecting all races and ethnic groups.2 From the perspective of clinical presentation, DMD and BMD appear in preschool children. While a child with DMD tends to become bedridden by 10–12 years, those with BMD tend to be ambulatory even into their adulthood. Parents consult a physician with complaints regarding their child’s weakness, inability to walk in a previously walking child, frequent falls, difficulty in climbing stairs, and abnormal swelling of the calf musculature.
Classification of Myopathy
Published in Maher Kurdi, Neuromuscular Pathology Made Easy, 2021
Based on all the information mentioned earlier, myopathy is better classified clinicopathologically. For example, when you have a case presenting with myopathic features, you start looking at the cytological details of muscle fibers. Presence of vacuolations means that we deal with “vacuolar myopathy” whereas presence of protein aggregates means we are dealing with “protein aggregate myopathies,” such as myofibrillar myopathies (MFM). Both protein aggregates and vacuolations could meet in one clinical diagnosis, MFM. In those cases, we understand that the pathological term vacuolar myopathy has been used to describe the clinical diagnosis of MFM.Figure 13.1 illustrates the clinicopathological classification of myopathies in muscle biopsy practice.
Ophthalmological Manifestations of Hereditary Myopathies
Published in Journal of Binocular Vision and Ocular Motility, 2022
Marta Saint-Gerons, Miguel Angel Rubio, Gemma Aznar, Ana Matheu
Congenital myopathies are a clinically and genetically heterogeneous group of muscle diseases that begin generally in childhood. They present with motor weakness, hypotonia, and motor development delay with a static or slow progression. The ophthalmological features include ptosis and ophthalmoparesis. Congenital myopathies can be classified based on their histology. The five types are centronuclear myopathy (subtypes: myotubular myopathy and autosomal centronuclear myopathy), nemaline myopathy, core myopathy, myosin storage myopathy, and congenital fiber-type disproportion.1In the last 15 years, more than 20 genes causing these diseases have been identified.2 These genes are implicated in an abnormal excitation-contraction coupling, malformation of contractile filaments, or regulation of calcium homeostasis.3,4 However, there is an important overlap, as different mutations in the same gene can cause distinct muscle pathologies, and mutations in different genes can cause very similar phenotypic defects5,6 (Table 1).
Inflammatory myopathies: shedding light on promising agents and combination therapies in clinical trials
Published in Expert Opinion on Investigational Drugs, 2021
Rachel Zeng, Stefanie Glaubitz, Jens Schmidt
Therapy development for inflammatory myopathies remains a challenge due to the rarity and heterogeneity of the disease. Although many pharmacological agents have been proposed, only few have been adequately evaluated in larger, well-controlled trials. Current development focuses on biologicals that target specific components of the immunological response, or – in IBM–, of nonimmune-mediated pathways. The use of standardized response criteria and myositis classification schemes is of great benefit to the conduction of clinical trials and the interpretation of study data. Future investigations will depend on sound scientific research on disease mechanisms and well-designed controlled clinical trials, which will hopefully translate into better clinical outcomes for myositis patients in the future.
Seronegative necrotizing autoimmune myopathy with favorable response to intravenous immunoglobulin
Published in Baylor University Medical Center Proceedings, 2021
Rebecca Liu, Andrew Z. Fenves, Samantha N. Champion, Jonathan Dau
Inflammatory myopathies consist of a heterogenous group of diseases characterized by chronic muscle inflammation and weakness. On the basis of clinical, serological, and pathological features, inflammatory myopathies are currently classified into five subgroups: dermatomyositis, polymyositis, NAM, inclusion-body myositis, and overlap myositis.1 Differentiating these subtypes can be challenging due to the overlapping manifestations and the still evolving diagnostic criteria given the lack of mechanistic understanding of these disorders. NAM typically manifests with subacute symmetrical proximal skeletal muscle weakness, often with more pronounced symptoms in the lower extremities. Patients with NAM may also exhibit neck muscle weakness and dysphagia. Potential risk factors for NAM include statin exposure,2 cancer,3,4 or connective tissue disease.4 A markedly high CK level is characteristic of NAM, with a median range between 4000 and 7000 IU/L.5 NAM by histopathology is characterized by prominent muscle necrosis and regeneration. Unlike other inflammatory myopathies, however, NAM muscle biopsies typically demonstrate minimal or no inflammatory infiltrates.6 Anti-HMGCR and anti-SRP antibodies are two serum autoantibody markers known to associate with NAM. While most patients with NAM have antibodies against HMGCR or SRP, approximately one-third of the patients are seronegative to either autoantibody.1,6