P-NE018. The importance of paying attention to the waveform pattern of the f wave in a patient with cerebrovascular diseases who showed markedly increased muscle tone of the thenar muscles

Abstract

Introduction . We investigated F wave in a patient with cerebrovascular diseases in which there was no voluntary movement of the hand, especially the thumb, due to markedly increased tone of the thenar muscles. We experienced a case in which characteristic change in the appearance pattern of F wave and the effect of rehabilitation. Methods . Case was a patient with right hemiplegia due to left cerebral hemorrhage (putamen) who showed markedly increased muscle tone of thumb flexors (MAS 4) and no voluntary movements. F-waves were recorded from the affected thenar muscles with median nerve stimulation (0.5 Hz, 30 times) in supine position. Exercise therapy, which included stretching of the affected thenar muscles were also carried out, and subsequent changes in the F-wave waveform were examined. The exercise therapy was performed twice a week for 20 minutes each session. Results . An F-wave with an average latency of 28.6 ms appeared after the appearance of the M-wave. However, various forms of F-wave-like waveforms were observed during the short latency (19.9 ms). No discharge of the short latency waveform was observed without electrical stimulation. After 3 months of exercise therapy, the short latency waveform disappeared, muscle tone was slightly improved (MAS 3), and voluntary movements of the paralyzed thumb was also appeared a little. Conclusion . The short latency waveform was not identical, and therefore cannot be considered to be axonal reflexes. As this waveform was not observed without electrical stimulation, the possibility that the excitability of the anterior horn cells of the spinal cord may have been increased. In addition, since exercise therapy improve muscle tone and did not show the appearance of the short latency, it is necessary to pay attention to the waveform pattern of F waves to evaluate spasticity in which markedly increased muscle tone in patients with cerebrovascular diseases.