SERIAL RECORDING OF SOMATOSENSORY AND MYOELECTRIC MOTOR EVOKED-POTENTIALS - ROLE IN ASSESSING FUNCTIONAL RECOVERY AFTER GRADED SPINAL-CORD INJURY IN THE RAT
R. Nashmi et al., SERIAL RECORDING OF SOMATOSENSORY AND MYOELECTRIC MOTOR EVOKED-POTENTIALS - ROLE IN ASSESSING FUNCTIONAL RECOVERY AFTER GRADED SPINAL-CORD INJURY IN THE RAT, Journal of neurotrauma, 14(3), 1997, pp. 151-159
Accurate functional outcome measures are essential in assessing therap
eutic interventions after experimental spinal cord injury (SCI). We ex
amined the hypothesis that serial recording of somatosensory (SSEP) an
d myoelectric motor evoked potentials (mMEPs) would provide complement
ary information to standard methods of behavioral analysis in a rat mo
del of SCI and would allow objective discrimination of functional reco
very in sensory and motor tracts. Clip compression injury of varying s
everity (sham, 23 g, 34 g, 56 g) and transections were performed at T1
in adult rats. SSEPs were recorded from the right sensorimotor cortex
(SMC) after stimulation of the contralateral hind paw; mMEPs were rec
orded from the paraspinal, quadriceps, and the tibialis anterior muscl
es after anodal stimulation of the SMC. The inclined plane and Tarlov
techniques were used to assess clinical neurological function. All out
come measures were assessed weekly prior to and up to 6 weeks followin
g injury. Changes in clinical neurological function as assessed by the
inclined plane and Tarlov methods varied with increasing injury sever
ity (R = -0.72 and R = -0.73, respectively). SSEP latency was strongly
correlated with injury severity (R = 0.92) and with clinical behavior
al scores (R = -0.93 for inclined plane). The tibialis anterior mMEP c
orrelated significantly, though weakly, with changes in inclined plane
(R = 0.49) and Tarlov scores (R = 0.41). Although the mMEPs were sens
itive to the presence of SCI, these recordings did not discriminate be
tween severities of injury. We conclude that serial recording of SSEPs
but not myoelectric MEPs correlates closely with the extent and tempo
ral course of clinical neurological recovery after graded SCI in the r
at.