[Differential diagnosis of thyrotoxic myopathy]

To differentiate between thyrotoxic myopathy and myodystrophy (of the limb-girdle type), severe myasthenia, polymyositis, Addison's disease, proximal spinal muscular atrophy, steroid myopathy and neurosis special diagnostic indices have been developed based on specific muscular weakness (and atrophy) pattern early in the disease, the sequence of separate muscles involvement as the pathological process progresses, disproportion between muscular weakness and atrophy, excessive folds of the skin above the affected muscles and the presence of deep reflexes, purposeful analysis of the anamnesis. The diagnosis is confirmed by thyroid function study and/or myopathy regression in response to antithyroid therapy.