Peripheral neurotoxicity testing by pairs of stimuli

At the present time the best electrophysiological test of peripheral nerve function for purposes of evaluating neurotoxicity in humans is the analysis of the response to pairs of stimuli. This test is a more sensitive measure of axonal conduction deficit than is the single-action potential of standard clinical technique. While not as sensitive a measure as a train of stimuli at any given frequency of stimulation, the paired stimulus technique has the following advantages. The interpretation of responses to trains of impulses can be made inaccurate by alternate blocking. Under such conditions the pairs response will already have shown impaired conduction, The method is sufficiently sensitive that the second response of the pair is decreased in normals. Thus the test will show any neurotoxic impairment which is additive to such normal physiological decrement. The method has already been reported in the literature as being sensitive to a number of different peripheral and central neuropathies in humans, including segmental demyelination and axonal degeneration. The equipment required is often already in the standard clinical facility, or can be added at reasonable cost. Stimulation with pairs is more acceptable to the subject since it is not as painful as presentation of stimulus trains.