Somatosensory evoked potentials in cerebral palsy after partial dorsal root rhizotomy.

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.