Nerve rootlets to be sectioned for spasticity resolution in selective dorsal rhizotomy

BACKGROUND The goal of this study is to confirm the efficacy of the protocol for selec tive dorsal rhizotomy (SDR). In this protocol, rootlets to be sectioned are selected by palpable responses elicited by intraoperative electrical stimu lation, without detailed electromyographic classifications. METHODS Thirty-six children with spasticity due to cerebral palsy underwent SDR acc ording to our protocol. Priority was given to sectioning rootlets that show ed palpable clonic or bilateral responses, which were considered abnormal, over sectioning rootlets that merely had hyperactive responses to intraoper ative stimulation. The results of intraoperative monitoring and sectioning amount were analyzed by physical evaluation. RESULTS Significant improvements were obtained in passive range of motion and muscl e tone of the lower extremities. The total percentages of rootlets with abn ormal and hyperactive responses at L3 and S1 were bilaterally correlated wi th preoperative spasticity of the hip adductors and the plantar flexors, re spectively. When rootlets with hyperactive responses were excluded from the correlation analysis, no bilateral correlation was observed. From the corr elation analyses between the improvement in the physical evaluation and the amount of nerve sectioned, it was concluded that a greater improvement in muscle tone in all examined muscles, except the hamstrings, could be obtain ed if larger amounts of nerve roots were sectioned. CONCLUSION The number of rootlets with palpable abnormal and hyperactive responses eli cited by intraoperative stimulation reflects the preoperative spasticity of multiple muscles. This implies that only selecting rootlets with palpable responses can be reliable. Because more sectioning leads to better spastici ty resolution, our protocol should be reviewed to increase the percentage o f rootlets sectioned with hyperactive responses, especially for innervated levels of severely affected muscles. (C) 2000 by Elsevier Science Inc.