Bc. Warf et Kr. Nelson, THE ELECTROMYOGRAPHIC RESPONSES TO DORSAL ROOTLET STIMULATION DURING PARTIAL DORSAL RHIZOTOMY ARE INCONSISTENT, Pediatric neurosurgery, 25(1), 1996, pp. 13-19
Concerns have arisen regarding the ability of physiologic techniques t
o select rootlets mediating spasticity in children undergoing partial
dorsal rhizotomy (PDR) for the treatment of spastic gait from cerebral
palsy. To determine whether these physiologic responses are reproduci
ble, 60 rootlets in 6 patients were graded from 0 to 4+ according to t
he system first reported by Phillips and Park, and then retested and g
raded using a randomized, blinded paradigm. Two thirds of the rootlets
had one or more grade difference between the two trials, and 25% had
a grade change of 3 or more. Only 4 of 23 rootlets with a 'normal' res
ponse (grade 0) on one test were also graded normal on the other test.
Only 2 of 14 rootlets with a bilateral response (grade 4+) had a bila
teral response on both trials. Statistical analysis demonstrated no co
rrelation and poor agreement between trials. Regardless of whether res
ponses are reflex in origin with technical or physiologic variability,
or the consequence of stimulus spread to ventral roots, we found inco
nsistent responses with commonly used methods and the criteria most ag
reed upon. These findings suggest that currently used techniques are n
ot reliable for rootlet 'selection' and result only in a random partia
l rhizotomy.