Sectorial posterior rhizotomy, a new technique of surgical treatment for spasticity.

After their experience of Foerster's operation and its technical modifications in 80 cases the authors report a new concept of analysis and treatment of spasticity in lower limbs. Spasticity of the different muscle groups is classified either as "useful spasticity" or "handicapping spasticity". The first has to be preserved, the second must be reduced. In order to achieve this purpose a new technique is presented, based on operative sectorial identification of the posterior rootlets subserving the "handicapping spasticity" by electrophysiological stimulation, muscle testing, and E.M.G. studies. The conus medullaris and cauda equina are exposed by T 11-L 1 laminectomy, performed in the lateral position. The clinical and E.M.G. evaluation of responses to stimulation enables the surgeon to establish a map of rootlet groups which are marked with coloured threads. Selective resection of "handicapping posterior rootlets" is then performed after several tests of the mapping. The rootlets subserving useful spasticity are carefully preserved. Ten cases are reported, comprising five cases of cerebral palsy operated upon since 1974 and five cases of posttraumatic spastic paraplegia from the same period. Pre and postoperative findings are summarized. The technical features of this procedure are discussed and compared with other surgical procedures. The problem of the rootlet reflex arch is considered in the light of the effects of stimulation of anterior and posterior rootlets at the same level.