Somatosensory evoked potentials in cerebral palsy after partial dorsal root rhizotomy
M. Kundi, L. Cahan and A. Starr
Department of Neurology, University of California, Irvine 92717.
Somatosensory evoked potentials (SEPs) were studied in 20 children with
cerebral palsy and severe lower extremity spasticity before and after
selective partial dorsal root rhizotomy of the lumbosacral cord. The
potentials from stimulating nerves in the lower extremity were abnormal in
two thirds of the children before the operation, whereas the potentials
were generally normal from upper extremity nerves. Dorsal root rhizotomies
caused an attenuation of nerve root entry volleys recorded over the lumbar
cord but did not change SEPs recorded over the cortex. The exception to
this was that the incidence of abnormal sural nerve SEPs decreased
postoperatively. Lumbar cord functions measured by H-reflexes or by tendon
jerks were depressed following the operation. These results indicate a
significant degree of abnormality of somatosensory transmission from the
lower extremity in a group of cerebral palsied children with severe
spasticity. Moreover, selective sectioning of approximately 50% of the
dorsal root fibers in the lumbosacral cord had little influence on cortical
evoked potentials.