PREOPERATIVE INDICATORS OF CLINICAL OUTCOME FOLLOWING STEREOTAXIC PALLIDOTOMY

We assessed the utility of preoperative clinical assessment and functi onal brain imaging with F-18-fluorodeoxyglucose (FDG) and positron emi ssion tomography (PET) in predicting the clinical outcome of stereotax ic pallidotomy for the treatment of advanced Parkinson's disease (PD). Twenty-two PD patients undergoing posteroventral pallidotomy were ass essed preoperatively with the Core Assessment Program for Intracerebra l Transplantation (CAPIT) ratings measured on and off levodopa; quanti tative FDG/PET was also performed before surgery. Preoperative clinica l and metabolic measurements were correlated with changes in off-state CAPIT ratings determined 3 months after surgery. Clinical outcome fol lowing pallidotomy was also correlated with intraoperative measures of spontaneous pallidal single-unit activity as well as postoperative MR I measurements of lesion volume and location. We found that unilateral pallidotomy resulted in variable clinical improvement in off-state CA PIT scores for the contralateral limbs (mean change 30.9 +/- 15.5%). P ostoperative MRI revealed that pallidotomy lesions were comparable in location and volume across the patients. Clinical outcome following su rgery correlated significantly with preoperative measures of CAPIT sco re change with levodopa administration (r = 0.60, p < 0.005) and with preoperative FDG/PET measurements of lentiform glucose metabolism (r = 0.71, p < 0.0005). Operative outcome did not correlate with intraoper ative measures of spontaneous pallidal neuronal firing rate. We conclu de that preoperative measurements of lentiform glucose metabolism and levodopa responsiveness may be useful indicators of motor improvement following pallidotomy. Both preoperative quantitative measures, either singly or in combination, may be helpful in selecting optimal candida tes for surgery.