Semirhythmic, Semicircular, Writhing Contractions of the Dorsal Region While Standing

Resolution with voluntary muscle contraction and stretching, decubitus position, and tactile stimulation. Needle electromyography of the bilateral trapezii showing (1) tonic activity with superimposed alternating, semirhythmic, 0.5- to 2-Hz, 0.4- to 0.6-second bursts of grouped, normal motor unit potentials recruited in a crescendo-decrescendo pattern and (2) attenuation of muscle activity approximately 0.6 seconds after tactile stimulation.