Electroencephalography and clinical neurophysiology
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Electroencephalogr Clin Neurophysiol · Apr 1991
Randomized double pulse stimulation for assessing stimulus frequency-dependent conduction in injured spinal and peripheral axons.
Injury compromises the ability of axons to conduct action potentials at high frequencies. To study stimulus frequency-dependent conduction in injured spinal and peripheral axons, we developed a new stimulation paradigm which applies trains of double pulses at 5 Hz and randomly varied interpulse intervals of 3, 4, 5, 8, 10, 30, 50, and 80 msec. In each double pulse, the first pulse was used to condition the response activated by the second test pulse. ⋯ Spinal cord injury did not affect the dorsal root responses. L5 root compression injury depressed dorsal root action potentials at 3-5 msec interpulse intervals (36.9 +/- 8.4%, n = 4, P less than 0.0001) but had no other effect on the responses. Our data indicate that randomized double pulse evoked potentials are sensitive detectors of acute axonal dysfunction and can be used to quantify stimulus frequency-dependent conduction deficits in injured central and peripheral axons.