Myotonia congenita is a hereditary chloride channel disorder characterized by delayed relaxation of skeletal muscle (myotonia). It is caused by mutations in the skeletal muscle chloride channel gene CLCN1 on chromosome 7. The phenotypic spectrum of myotonia congenita ranges from mild myotonia disclosed only by clinical examination to severe and disabling myotonia with transient weakness and myo...

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The presence of myotonia and paramyotonia on clinical examination and of myotonic discharges during electrodiagnostic (EDX) studies are important for the diagnosis of certain neuromuscular conditions. The increased muscle activity of myotonia produces muscle stiffness that improves with repeated activity. Paramyotonia produces a similar symptom, but the stiffness paradoxically increases with ac...

the myotonic disorders are a heterogeneous group of genetically determined diseases that are unified by the presence of myotonia, which is defined as failure of muscle relaxation after activation. the presentation of these disorders can range from asymptomatic electrical myotonia, as seen in some forms of myotonia congenita (mc), to severe disability with muscle weakness, cardiac conduction def...

Fourteen patients with paramyotonia congenita were examined clinically. Patients of 3 families had no myotonia in a warm environment while in a cold environment they developed paradoxical myotonia (myotonia aggravated by repeated muscle contraction). Patients of a 4th family had myotonia associated with after-activity in a warm environment which was not paradoxical. This myotonia was aggravated...

A patient with subclinical hypothyroidism who presented with true myotonia is described. There was no evidence that either he or members of his family had dystrophia myotonica or myotonia congenita. Treatment with thyroxine resolved his symptoms completely.

Twenty-five Turkish patients with recessive myotonia congenita (RMC), 16 of whom had genetic confirmation, were studied. Nineteen had transient weakness. In the upper extremities, onset age of transient weakness was usually in the early teens. All untreated RMC patients had a compound muscle action potential decrement of > or =25%, usually above 50%, with repetitive nerve stimulation at 10/s fo...

BACKGROUND AND PURPOSE Fatigue and pain have been previously shown to be important determinants for decreasing quality of life (QoL) in one report in patients with non-dystrophic myotonia. The aims of our study were to assess QoL in skeletal muscle channelopathies (SMC) using INQoL (individualized QoL) and SF-36 questionnaires. METHODS We administered INQoL and SF-36 to 66 Italian patients wi...

A sporadic Japanese case of myotonia congenita with painful muscle cramps is reported. Electromyographic examinations disclosed myotonic discharge with dive bomber sounds at insertion, and high-amplitude, high-frequency motor unit potentials during the muscle cramps. Biopsied muscle specimens and EMGfindings showednon-specific mild myopathic changes. There was no abnormal expansion of CTGrepeat...

Myotonia is a failure of voluntary muscle to relax immediately innervation ceases. The clinical and electrical manifestations reflect a primary abnormality of the muscle cell membrane. Myotonia is commonly observed in three syndromes. (1) Myotonia congenita (Thomsen, 1876), is an inherited condition, transmitted by a dominant gene. The myotonia affects all muscles which are often hypertrophied....