PMC7260604_01
Right median motor nerve before 20 Hz stimulation; supramaximal stimulation at wrist and forearm, recording APB. Site 1 - Wrist. Site 2 - Forearm. Right median motor nerve distal latency, CMAP amplitude, and conduction velocity are normal.
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The nerve conduction studies including CMAP amplitudes, latencies, and velocities were normal (Fig. 1).
Right median motor F-waves: 10 trials of supramaximal stimulation delivered at 1/s, before a brief 20 Hz stimulation. As you see, there are no F-waves. Clinically, the patient has 2/5 flaccid weakness (Medical Research Council scale for muscle strength). Right median motor nerve stimulated at wrist, recording APB (abductor pollicis brevis).
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However, initial recordings from the median nerve at the abductor pollicis brevis demonstrated absent F-waves (Fig. 2).
Right median motor F-waves: 8 trials visualized on the graph, using supramaximal stimulation delivered at 1/s, after a brief (1 s) 20 Hz stimulation. As you see, the emergence of F-waves is pronounced. Persistence is normal (>50% of stimulations produces an F-wave). Right median motor nerve stimulated at wrist, recording APB (abductor pollicis brevis).
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After performing a 1-second burst of 20 Hertz (Hz) repetitive nerve stimulation of the median nerve, F-waves were easily obtained 1 s after RNS was completed (Fig. 3).