K. Grabitz et al., SOMATOSENSORY-EVOKED POTENTIAL, A PROGNOSTIC TOOL FOR THE RECOVERY OFMOTOR FUNCTION FOLLOWING MALPERFUSION OF THE SPINAL-CORD - STUDIES INDOGS, Journal of clinical monitoring, 9(3), 1993, pp. 191-195
The potential usefulness of somatosensory evoked potential monitoring
during aortic cross-clamping is slowly being realized. In addition, th
e protection of endangered spinal nervous tissue during aortic cross-c
lamping has not been sufficiently evaluated. To test the pharmacologic
protective efficacy of various agents, we recorded spinal evoked soma
tosensory potentials (bipolar epidural catheter) in dogs under control
led conditions (N2O/O2-enflurane anesthesia) following clamping of the
aorta for 1 hour. There were 5 groups of animals: those treated with
different medications, such as prostaglandin E1 (PGE1), prostacyclin (
PGI2), superoxide dismutase (SOD), and PGE1 plus SOD for pharmacologic
protection during ischemia, and the controls. The time to recovery of
evoked potentials during the reperfusion period was 36 minutes in the
controls, 15.9 minutes in the SOD group (p < 0.01), 12.5 minutes in t
he PGE1 group (p < 0.001), 10.8 minutes in the PGI2 group (p < 0.001),
and 3.8 minutes in the combination group (p < 0.001). In addition, tr
eatment resulted in a better neurologic outcome on the seventh postope
rative day when compared with the control group. While in the control
group only 1 animal could walk (9%), 7 of 12 in the PGE1 group (58%),
4 of 12 in the SOD group (33.8%), 8 of 12 in the PGI2 group (66.7%), a
nd all animals in the combination group (100%) could walk. We computed
an exponential correlation that related the mean time of potential re
covery during reperfusion with Tarlov scoring (grade 0 = paraplegia; g
rade 1 = paraplegia with little movements; grade 2 = paraparesis; grad
e 3 = paraparesis with some problems; grade 4 = normal motor function)
in the various groups. On the seventh postoperative day r = 0.97 and
the regression equation was y = 50.6 x 10(-0.28x). The correlation ref
lects a close relationship between late postoperative outcome of motor
function and early intraoperative regeneration of somatosensory poten
tials after declamping. We conclude that (1) spinal evoked potential c
an be used as a prognostic tool to indicate recovery of motor function
of the lower extremities after aortic clamping, and (2) during aortic
cross-clamping the endangered spinal cord can be protected by means o
f pharmacologic treatment.