POSTEROVENTRAL MEDIAL PALLIDOTOMY FOR TREATMENT OF PARKINSONS-DISEASE- PREOPERATIVE MAGNETIC-RESONANCE-IMAGING FEATURES AND CLINICAL OUTCOME

Object. The goal of this study was to investigate the impact of mild o r moderate degrees of degenerative or ischemic encephalopathy on predi cting clinical outcome following unilateral posteroventral medial pall idotomy for treatment of advanced Parkinson's disease (PD). Methods. T hirty-five patients with PD were studied prospectively. The presence a nd degree of cortical atrophy, ventriculomegaly, deep white matter les ions (DWML), periventricular lucencies (PVL), and the presence of lacu nes and status cribriformis (multiple and bilateral enlarged Virchow-R obin spaces) were determined by magnetic resonance (MR) imaging before the patients underwent stereotactic pallidotomy performed according t o a standard protocol. Clinical outcome was measured using a standard battery of tests including application of the Unified Parkinson's Dise ase Rating Scale (UPDRS). The preoperative MR imaging features were co rrelated with UPDRS subscores such as motor ''off'' score, the activit ies of daily living (ADL) off score, the off subscore for bradykinesia , the percentage of ''on'' time dyskinesias, and a global outcome rati ng. The MR findings were also correlated with the occurrence of side e ffects. Global outcome was rated as markedly improved in 22 patients ( 63%) and as moderately improved in 12 patients (34%) 6 months postoper atively. At the 1-year follow-up examination, global outcome in 31 pat ients was rated as markedly improved in 14 patients (45%), as moderate ly improved in another 14 (45%), as slightly improved in two (6%), and as worse In one patient (3%). The mean UPDRS motor off score changed from 58.7 preoperatively to 33.2 at 6 months and 33.4 at 1 year (p < 0 .0001), the ADL off score from 31.8 to 18.2 at 6 months and 18.6 at 1 year (p < 0.0001), the off score from contralateral bradykinesia from 11.6 to 5.6 at 6 months and 4.1 at 1 year (p < 0.0001), and the percen tage of awake time with dyskinesias from 37.4 to 17.4% at 6 months and 21.1% at 1 year(p < 0.0001). The presence of mild or moderate degrees of cortical atrophy, PVL, and DWML had no effect on clinical outcome. Patients with status cribriformis and chose with lacunes tended to sh ow comparatively less improvement in the UPDRS ADL off score (p = 0.01 4 and p = 0.016, respectively) at 6 months. This tendency was also pre sent in patients with status cribriformis 1 year postoperatively (p = 0.046). Patients with both status cribriformis and lacunes had a highe r incidence of transient altered mental status immediately postoperati vely (p = 0.05). Conclusions. Mild-to-moderate degrees of cortical atr ophy, ventriculomegaly, and ischemic encephalopathy do not predispose patients to less favorable outcomes following unilateral pallidotomy. Patients with both status cribriformis and lacunes have a higher risk of transient side effects; however, with regard to clinical outcome, t hese patients should not be denied surgical treatment.