[H-reflex of the flexor carpi radialis in healthy subjects and in nervous system pathology]

More than half of a series of healthy adults subjected to electrical stimulation of the median nerve from the wrist radial flexor showed not only the direct M-response but also H-reflex. The ratio of the maximal amplitudes of the H-reflex and M-potential (H max/M max) averaged 11.5 +/- 2.2%. In patients presenting a clinical picture of the pyramidal syndrome, the H-reflex was induced in all observations while the H max/M max was on the average 34.3 +/- 9.7%. In patients with a combination of conduction and segmental disturbances at the cervical level, the central response was absent in some studies whereas in others it had antidromal or reflex nature. All cases with polyneuropathies and median nerve impairments exhibited the absence of the late potential of the wrist radial flexor. A conclusion is drawn about the diagnostic value of the central response of the studied muscle.