[Determination of average fiber density (single fiber lead), quantitative electromyography and serum CK in the detection of Duchenne carriers].

The fibre density of the extensor digitorum communis muscle was examined with a monopolar single fiber electrode in 2 definite, one probable and 15 possible Duchenne-carriers. In addition serum-CK was evaluated three times in intervals of a least one week. The fibre density was increased in one definite, one probable and 4 possible carriers (greater than 1.6). The highest value was 2.0. Excepting one case the increase of fibre density was accompanied by an increase of serum-CK (greater than 60 mg%). The highest value of CK was 1626 mg%. The conventional EMG was pathological in 2 cases. In no case with an increase of CK or with pathological EMG the fibre density was normal. The fibre density is an unspecific but rather sensible indicator of Duchenne-carriers but as we could observe in a definite carrier, negative results do not exclude carriers.