Differential Diagnosis of Thyrotoxic Myopathy

Abstract

Along with hereditary myopathies, there are many exogenic (the same a not hereditary) muscle affections due to the pathology of endocrine gland’s functioning. These forms of muscle pathology are called endocrine myopathies. In the cases of thyroid gland hyperfunction (the same a thyrotoxicosis), different regions of neuromuscular system may be involved in the pathological process. Thyrotoxic myopathy (TM) which is a subject of this investigation, occupies one of the first places between thyrotoxic (the same a thyrotoxicosis) neuromuscular affections. Meanwhile, for a long time in literature there was no clarity about the degree of muscle weakness and atrophy to diagnose TM in a patient. It’s because of the fact that the majority of patients complain of increased fatigue and general weakness due to thyrotoxicosis. In present time TM diagnostics is very rare. TM is a phenocopy (the clinical similar) of many neuromuscular diseases. However in literature, the data about peculiarities of clinical picture of TM is almost completely absent, it isn’t known about the frequency of affection of the isolated muscles or muscle groups, the topography of muscle weakness and successive involvement of isolated muscles in the pathological process during different stages of thyrotoxicosis and myopathy. The questions of differential diagnosis with similar neuromuscular disorders are described very poorly. In present article, we accent our attention at the clinical differentiation of the TM with other neuromuscular diseases, namely muscular dystrophy, myasthenia gravis, polymyositis, Addison’s disease, proximal spinal muscular atrophy, steroid myopathy and neurosis. In our opinion, the early diagnosis of TM may help the diagnosis of thyrotoxicosis in patients who have no classical clinical signs of this disease, i.e. in patients with latent thyrotoxicosis.