Although the sodium channel blocker mexiletine is considered the first-line drug in myotonia, some patients experiment adverse effects, while others do not gain any benefit. Other antimyotonic drugs are thus needed to offer mexiletine alternatives. In the present study, we used a previously-validated rat model of myotonia congenita to compare six marketed sodium channel blockers to mexiletine. ...

Nearly 20 years ago Evans (1944) suggested that the cardiac abnormalities that are associated with myotonia atrophica might in some cases be an important aid to the early diagnosis of this disease. This report concerns a patient who was first thought to be a case of non-specific myocarditis, but who later proved to be one of cardiomyopathy due to myotonia atrophica after a family history of thi...

Centronuclear myopathy, which is unusual because of clinical myotonia, is described in two sisters. The diagnosis was established in adult life, but the first symptoms were noticed in infancy. The outstanding points of the clinical picture were mild amyotrophy, paresis, and clinical myotonia.

Today, we have heard about several rare diseases and I am about to add another to the pile. This seems to me entirely appropriate to this occasion. Malcolm Campbell, as has been said, was a keen student of natural history. He took a special delight in the recognition of an unusual condition. I should like to add my tribute to his memorial. Myotonia is a sustained contraction of muscle fibres ca...

Myotonic dystrophy type 2 (DM2) is an autosomal dominant disorder with proximal weakness, muscle pain, and early-onset cataracts. In comparison with myotonic dystrophy type 1 (DM1), myotonia is less symptomatic, more proximal, and harder to detect during clinical and electrodiagnostic testing. Here we document the presence of trapezius myotonia in patients with DM2 (video on the Neurology® Web ...

Congenital recessive myotonia is a rare genetic disorder caused by mutations in CLCN1, which codes for the main skeletal muscle chloride channel ClC-1. More than 120 mutations have been found in this gene. The main feature of this disorder is muscle membrane hyperexcitability. Here, we report a 59-year male patient suffering from congenital myotonia. He had transient generalized myotonia, which...

1. Mutations that impair inactivation of the sodium channel in skeletal muscle have recently been postulated to cause several heritable forms of myotonia in man. A peptide toxin from Anemonia sulcata (ATX II) selectively disrupts the inactivation mechanism of sodium channels in a way that mimics these mutations. We applied ATX II to rat skeletal muscle to test the hypothesis that myotonia is in...

The CLC-1 chloride channel, a member of the CLC-channel/transporter family, plays important roles for the physiological functions of skeletal muscles. The opening of this chloride channel is voltage dependent and is also regulated by protons and chloride ions. Mutations of the gene encoding CLC-1 result in a genetic disease, myotonia congenita, which can be inherited as an autosmal dominant (Th...