Enrico Fazzini

Stereotactic pallidotomy for Parkinson's disease A long‐term follow‐up of unilateral pallidotomy

Eleven patients suffering from Parkinsons disease were followed for up to 4 years after unilateral pallidotomy. We observed persistent contralateral improvement and unexpected ipsilateral improvement of motor symptoms. In addition, there was a protracted relief of contralateral dyskinesias and maintenance of relatively stable levodopa dosage.

Preoperative indicators of clinical outcome following stereotaxic pallidotomy

We assessed the utility of preoperative clinical assessment and functional brain imaging with 18F-fluorodeoxyglucose (FDG) and positron emission tomography (PET) in predicting the clinical outcome of stereotaxic pallidotomy for the treatment of advanced Parkinsons disease (PD). Twenty-two PD patients undergoing posteroventral pallidotomy were assessed preoperatively with the Core Assessment Program for Intracerebral Transplantation (CAPIT) ratings measured on and off levodopa; quantitative FDG/PET was also performed before surgery. Preoperative clinical and metabolic measurements were correlated with changes in off-state CAPIT ratings determined 3 months after surgery. Clinical outcome following pallidotomy was also correlated with intraoperative measures of spontaneous pallidal single-unit activity as well as postoperative MRI measurements of lesion volume and location. We found that unilateral pallidotomy resulted in variable clinical improvement in off-state CAPIT scores for the contralateral limbs (mean change 30.9 ± 15.5). Postoperative MRI revealed that pallidotomy lesions were comparable in location and volume across the patients. Clinical outcome following surgery correlated significantly with preoperative measures of CAPIT score 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 intraoperative measures of spontaneous pallidal neuronal firing rate. We conclude 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 candidates for surgery.

Anatomic and Physiological Considerations in Pallidotomy for Parkinson's Disease

Our ongoing study of ventral pallidotomy for the control of Parkinsons disease in selected patients has provided the opportunity to explore the topographical and somatotopic organization of the human globus pallidus. Utilizing microelectrode techniques we have obtained recordings which were correlated with data from MPTP-parkinsonian primates. In addition, we performed pre- and post-operative FDG/PET scans in these patients. Our studies reveal similarities between the MPTP-parkinsonian primate model and human Parkinsons disease in terms of physiologic recordings and responses. However, we have encountered significant differences between dominant and non-dominant hemisphere representations, particularly for the hand, in the human. In addition, our PET studies confirmed, as in previous parkinsonian primate models, glucose hypermetabolism in the lenticular area of Parkinsons disease patients. This hypermetabolism is dramatically altered by creation of a lesion in the globus pallidus medialis. This is demonstrated by follow-up PET scans which reveal not only a decrease in metabolism of the operated lenticular region, but also in the frontal cortical projections. These combined observations of the cellular activity in the globus pallidus and the observed changes in PET metabolism support the selection of the pallidum for lesioning and control of Parkinsons disease, and offer insight into the underlying physiology of this disorder. The above physiological and PET data will be clinically correlated with our ongoing series of 35+ patients.

Cognitive functioning after pallidotomy for refractory Parkinson’s disease

BACKGROUND Earlier approaches to pallidotomy for refractory Parkinson’s disease had significant complication rates. More recent approaches show fewer complications, but the effect of pallidotomy on cognition is unclear. The current study was conducted to examine the neuropsychological effects of unilateral pallidotomy. METHODS Neuropsychological testing was performed on patients with medically refractory, predominantly unilateral Parkinson’s disease at baseline and after unilateral ventral pallidotomy (n=28) or after an equivalent period without surgery in control patients (n=10). RESULTS Pallidotomy patients showed no significant changes from baseline to retesting relative to the control group for any measure. Across all of the tests administered, only five of the surgery patients showed a significant decline, and of these five none declined on more than one test. Depression did not relate to preoperative or postoperative cognition. The pallidotomy group showed a significant improvement in motor functioning and activities of daily living whereas the control group did not. These measures were not associated with the neuropsychological test scores at baseline or retest. CONCLUSIONS Stereotactic unilateral ventral pallidotomy does not seem to produce dramatic cognitive declines in most patients.

Cerebrospinal fluid antibodies to coronavirus in patients with Parkinson's disease

The etiology of Parkinsons disease remains unknown, and a search for environmental agents continues. In 1985, Fishman (10) induced infection of the basal ganglia by a coronavirus in mice. Although coronavirus is recognized primarily as a respiratory pathogen in humans, its affinity for the basal ganglia led us to investigate its possible role in human Parkinsons disease. The cerebrospinal fluid of normal controls (CTL) (n = 18), and patients with Parkinsons disease (PD(n = 20)) and other neurological disease (OND) (n = 29) was analyzed in a blinded manner by enzyme‐linked immunosorbent assay [measurements in optical density (OD) units] for antibody response to four coronavirus antigens: mouse hepatitis virus JHM (J) and A59 (A), and human coronavirus 229E (E) and OC43 (O). When compared with CTL, PD patients had an elevated (p < 0.05) mean OD response to J (0.0856 vs. 0.0207) and A (0.1722 vs. 0.0636). Response (p > 0.05) to O (0.0839 vs. 0.0071) was greater than that to E (0.1261 vs. 0.0743). When compared to OND, PD patients had an elevated mean OD response to J (0.0856 vs. 0.0267, p < 0.05). Responses (p > 0.05) to A (0.1722 vs. 0.0929) and O (0.0839 vs. 0.0446) were greater than that to E (0.1261 vs. 0.0946). These results suggest that there may be an association between coronavirus and PD.

Selection Criteria for Unilateral Posteroventral Pallidotomy

In an attempt to refine the indications for posteroventral pallidotomy (PVP) the authors instituted strict selection criteria which are based on the experience gained from the first 60 pallidotomy patients treated at their institution. In addition to clinical evaluation, all pallidotomy candidates undergo neuropsychological testing and 18F-fluoro-deoxyglucose utilization positron emission tomography (FDG/PET). The data from which these criteria were developed are presented as are early clinical results. The authors demonstrate that these criteria enhance the efficacy of the procedure by assuring therapeutic response and reducing the incidence of post-operative dementia. Their indications and contraindications for pallidotomy are discussed.