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D. Rohde

Welander distal myopathy

Welander distal myopathy

Schlüsselwörter Welander distal myopathy; ICD 10: G71.0; late adult onset type 1 distal myopathy; distal myopathy Swedish type
Keywords Welander distal myopathy; ICD 10: G71.0; late adult onset type 1 distal myopathy; distal myopathy Swedish type
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Summary

Welander distal myopathy belongs to the group of distal myopathies. These are classified according to clinical features, inheritance pattern and histopathological criteria. Welander myopathy was first described by Lisa Welander in 1951. Inheritance occurs via autosomal dominant pathway. Welander myopathy has been linked genetically to the chromosome 2p13. This distal myopathy is almost exclusively found in Sweden and partly in Finnland. Clinically, Welander myopathy has a late adult onset with slow progression with a mean age of onset of 45 years and a normal life expectancy. First symptoms appear as weakness combined with atrophy of distal muscles of the upper extremity leading to problems in small precision movements as well as the inability to extend the fingers. As the disease progresses the distal muscles of the lower extremity can be affected. Tendon reflexes are decreased or absent. Sensory dysfunction may occur in form of elevated thresholds for thermal stimuli in the distal parts of upper and lower extremity. Proximal involvement was described by Welander in very few cases and is therefore very rare and maybe just found in homozygous carriers. Cardiac involvement has been excluded. Creatine kinase values are either normal or slightly elevated. Nerve conduction velocities are normal. In electromyography both myopathic and neurogenic changes can be found. These include small polyphasic motor-unit potentials, reduced interference pattern, giant motor-unit potentials and spontaneous activity. Histopathological analysis shows increased variation of muscle fiber diameter, centrally located nuclei, split fibers, rimmed vacuoles as well as atrophic fibers.

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