Special electromyographic features in a child with paramyotonia congenita: A case report and review of literature

Figure 1 Right rectus femoris (horizontal bar 20 ms/D, vertical bar 1 mV/D; horizontal bar 100 ms/D, vertical bar 1 mV/D; and horizontal bar 10 ms/D, vertical bar 0. 1 mV/D). A: Right rectus femoris (horizontal bar 20 ms/D, vertical bar 1 mV/D). The train of positive waves in myotonic discharges, displaying fluctuations in frequency and amplitude, with a frequency range of 70-150 Hz and an amplitude range of 0.5-3 mV, is depicted; B: Right rectus femoris (horizontal bar 100 ms/D, vertical bar 1 mV/D). A section of the train of positive waves in myotonic discharges showcases an oscillating pattern in amplitude and frequency, characterized by a rapid surge followed by a gradual decline; C: Right rectus femoris (horizontal bar 10 ms/D, vertical bar 0.1 mV/D). This represents a small section of the train of positive waves within myotonic discharge depicted in Figure 1B. A complete positive wave is visible, and the arrows denote the presence of negative phase waves, each exhibiting varying frequencies and shapes.