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Hind limb somatosensory evoked potentials in the monkey: The effects of distal axonopathy
Author(s) -
Arezzo J. C.,
Schaumburg H. H.,
Vaughan H. G.,
Spencer P. S.,
Barna J.
Publication year - 1982
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.410120105
Subject(s) - anatomy , spinal cord , brainstem , fasciculus , somatosensory system , somatosensory evoked potential , medial longitudinal fasciculus , peripheral , lumbar , medicine , neuroscience , stimulation , cauda equina , central nervous system , midbrain , anesthesia , biology , white matter , magnetic resonance imaging , fractional anisotropy , radiology
Computer‐averaged short‐latency somatosensory evoked potentials (SLSEP) to unilateral stimulation of the peroneal nerve were recorded from surface electrodes overlying the peripheral nerve, cauda equina, spinal cord, brainstem, and contralateral sensorimotor region. Seven monkeys were studied under normal conditions and at various stages of distal axonopathy induced by systematic acrylamide intoxication. With the use of a noncephalic reference, a series of five small‐amplitude positive components were identified that precede the initial cortical activity. On the basis of timing and topography of the components, the source of the first one, SLSEP1, was localized to the lumbar dorsal root fibers and that of the second, SLSEP2, to the ascending spinal tracts, principally the gracile fasciculus. Bipolar recordings of the SLSEP2 overlying the rostral extreme of the cervical spinal cord provided a sensitive measure of the onset of distal axonopathy. Changes in the timing of this component antedated both abnormalities of spinal or peripheral nerve conduction and behavioral signs of intoxication. The initial alteration was specific to stimulation of the hind limb and was associated with early morphological change limited to the terminal and preterminal portions of the long axons in the gracile fasciculus.