BACKGROUND Myotonia and periodic paralysis caused by sodium channel mutations show variable responses to the anti-myotonic drug mexiletine. OBJECTIVE To investigate whether variability among sodium channel mutants results from differences in drug binding affinity or in channel gating. METHODS Whole-cell sodium currents (I(Na)) were recorded in tsA201 cells expressing human wild-type (WT) an...

OBJECTIVE Oropharyngeal dysphagia is a common feature of patients with myotonic dystrophy and is not usually perceived due to their emotional deficits and lack of interest. The aim was to show the existence and frequency of subclinical electrophysiological abnormalities in oropharyngeal swallowing and to clarify the mechanisms of dysphagia in myotonic dystrophy. METHODS Eighteen patients with...

Electrical membrane properties of skeletal muscle fibers have been thoroughly studied over the last five to six decades. This has shown that muscle fibers from a wide range of species, including fish, amphibians, reptiles, birds, and mammals, are all characterized by high resting membrane permeability for Cl(-) ions. Thus, in resting human muscle, ClC-1 Cl(-) ion channels account for ∼80% of th...

Myasthenia gravis and myotonic dystrophy do not usually coexist; however, we present a rare case where both conditions coexisted. Herein, we describe a 34-year-old woman who presented with symptoms of myasthenia gravis with coexisting myotonic dystrophy. She complained of limb weakness, difficulty in chewing and swallowing, and ptosis. She also had myotonia. The patient’s brother also had simil...

TH S is an important and useful attempt to clarify one of the most unsatisfactory and difficult aspects of morphological pathology. Of great value to the pathologist, it will also inform neurologists and physicians of the place and limitations of biopsy diagnosis. As the authors point out, much difficulty is caused by the use of terms, such as necrosis, degeneration, and(i inflammation, whiclh,...

TH S is an important and useful attempt to clarify one of the most unsatisfactory and difficult aspects of morphological pathology. Of great value to the pathologist, it will also inform neurologists and physicians of the place and limitations of biopsy diagnosis. As the authors point out, much difficulty is caused by the use of terms, such as necrosis, degeneration, and(i inflammation, whiclh,...

Three patients with paramyotonia congenita and 3 control persons were biopsied for an in vitro investigation of the sarcolemmal membrane parameters and of the contractile properties of paramyotonic muscle. At 37 degrees C, paramyotonic muscle fibers had normal resting potentials, but on cooling to 27 degrees C they depolarized. Depolarization to -60 mV caused spontaneous activity, and further d...