[A study of F-wave and cervical evoked action potentials by cutaneous recording (author's transl)]

The measurement of nerve conduction velocity and electro-myography have been used as auxiliary means to diagnose spinal and peripheral neuropathies. But it is quite difficult to present to establish the diagnosis fo the diseases involving the so-called proximal segments, i.e., the root entry zone of the spinal cord, spinal nerve root and plexus, by either of these methods. In the present investigation, therefore, the diagnostic possibility of the F-wave and cervical evoked action potentials was explored for such diseases. The results obtained were as follows: 1) In 50 normal subjects, the average F-wave conduction velocity over the median nerve was 58.5 +/- 2.3 (S.D.) m/sec (wrist to spinal cord); 60.9 +/- 3.0 (S.D.) m/sec (elbow to spinal cord); and the range of the normal value was 54.1--62.8 m/sec and 55.5--66.5 m/sec respectively at a 5% level of significance. 2) The F-wave led out of the abductor pollicis brevis muscle by stimulating the median nerve showed abnormal patterns in cases with a localized lesion in the medullary segment of the C7, C8, Th1, and nerve root. 3) The F-wave is dependent of the efferent nerve fibers; representing their antidromic conduction, or the activation of a few motoneurons with a resulting centrifugal discharge. 4) By observing the F-wave diagnosis can be established for the abnormalities in the conduction of the proximal segment of the peripheral nerve and the anterior root of the spinal cord and the changes in the excitation level of the anterior horn cells. 5) From the cervical evoked action potentials by cutaneous recording, the diagnosis can be established for the abnormalities in the conduction of the proxial segment of the peripheral nerve, spinal posterior horn and posterior cord. 6) When the F-wave and the cervical evoked action potentials by cutaneous recording were applied to clinical cases with disturbances in the spinal cord, nerve root and plexus, peculiar changes in the parameter were characteristically observed in each disease. It was therefore confirmed that these methods are very useful in the diagnosis of functional impairment of the proximal segments of the peripheral nerve, the root entry zone and plexus of the spinal cord, and motoneurons.