THE FIRST report of muscular changes in hypothyroidism was Kocher's1 account of muscular enlargement, weakness, and slow movements in a young cretin. Many authors, however, credit Debré and Semelaigne,2 who renewed interest in this childhood syndrome and cured one of their cases with thyroid. In the meantime, Hoffmann3 described an adult with enlarged muscles, weakness, slow movements, and delayed relaxation. He differentiated the abnormal relaxation from myotonia by its failure to improve after several contractions, as occurs in myotonia, a distinction not confirmed until after clinical application of electro-myography 39 years later.4 Hoffmann3 also reported a cure with thyroid. Later authors described numerous cases in myxedematous adults who also had painful muscle spasms and muscle percussion reactions similar to myotonia. Electromyography, however, demonstrated electrical silence in most cases during the myotonic-like manifestations, hence the descriptive terms pseudomyotonia and myotonoid reaction.5,6
The major points
NORRIS FH, FANNER BJ. Hypothyroid Myopathy: Clinical, Electromyographical, and Ultrastructural Observations. Arch Neurol. 1966;14(6):574–589. doi:10.1001/archneur.1966.00470120006002
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