Radial nerve F-waves: normative values with surface recording from the extensor indicis muscle.
OBJECTIVE
In the present study we set out to obtain normative values for radial nerve F-waves, with surface recording from the extensor indicis muscle.


METHODS
Forty-nine patients with unrelated complaints were tested. Surface recording electrodes were placed on the extensor indicis muscle. This was found by asking the patient to extend the second digit against resistance. The active surface recording electrode was placed over the most distal portion of the muscle, near the radial border of the ulnar bone near the wrist. Stimulation was performed near the lateral epicondyle between the radial and ulnar bones.


RESULTS
The mean F-wave minimum latency was found to be 20.55 ms, with an upper limit of 24.35 ms. The absolute interside minimum latency difference was found to have a mean of 0.55 ms, with a maximum of 1.7 ms. The mean amplitude of the F-waves was 145.61 microV and the mean mF/M ratio was 0.022. F-waves were unobtainable in 2/62 (3.2%) of limbs. Normative values for the radial nerve motor response were also obtained. Three cases are described to illustrate the usefulness of the above technique.


CONCLUSIONS
It is technically feasible to record radial nerve F-waves from the extensor indicis muscle.
Papathanasiou
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ES
Department of Clinical Neurophysiology, The Cyprus Institute of Neurology and Genetics, 6 International Airport Avenue, P.O. Box 23462, 1683, Nicosia, Cyprus. neurophy@mdrtc.cing.ac.cy
Zamba
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Papacostas
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D000328:Adult; D002349:Carpal Tunnel Syndrome / Q000503:physiopathology; D004558:Electric Stimulation; D004566:Electrodes; D005071:Evoked Potentials / Q000502:physiology; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology* / Q000503:physiopathology; D009431:Neural Conduction / Q000502:physiology; D011826:Radial Nerve / Q000502:physiology* / Q000503:physiopathology; D013126:Spinal Nerve Roots / Q000502:physiology / Q000503:physiopathology; D017769:Ulnar Nerve Compression Syndromes / Q000503:physiopathology