Metabolic correlates of subthalamic nucleus activity in Parkinson's disease.

Overactivity of subthalamic nucleus (STN) neurons is a consistent feature of Parkinson's disease (PD) and is a target of therapy for this disorder. However, the relationship of STN firing rate to regional brain function is not known. We scanned 17 PD patients with (18)F-fluorodeoxyglucose (FDG) PET to measure resting glucose metabolism before the implantation of STN deep brain stimulation electrodes.

Success rate of motor evoked potentials for intraoperative neurophysiologic monitoring: effects of age, lesion location, and preoperative neurologic deficits.

Transcranial electrical stimulation with myogenic motor evoked potential (MEP) recording was used for intraoperative neurophysiologic monitoring in 341 consecutive "high-risk" neurosurgical or orthopedic procedures. Overall, the success rate for establishing reliable MEP response was 94.8% for upper extremities and 66.

Deep brain stimulation improves orthostatic regulation of patients with Parkinson disease.

Objective: To evaluate whether subthalamic nucleus (STN) stimulation has an effect on the orthostatic regulation of patients with Parkinson disease (PD), we studied cardiovascular regulation during on and off phases of STN stimulation.

Methods: We examined 14 patients with PD (mean age 58.1 +/- 5.

Location of the active contact within the subthalamic nucleus (STN) in the treatment of idiopathic Parkinson's disease.

Background: Chronic electrical stimulation of the subthalamic nucleus (STN) has been shown to be safe and effective in the treatment of medically refractory idiopathic Parkinson's disease. The clinically most relevant location of stimulation within the physiologically defined STN has not been confirmed. We reviewed the locations of active electrical contacts in 33 patients who underwent simultaneous bilateral STN deep brain stimulator (DBS) implantation.

Neuropsychological functioning following bilateral subthalamic nucleus stimulation in Parkinson's disease.

The cognitive effects of subthalamic nucleus (STN) stimulation in Parkinson's disease (PD) have been examined. However, there are no reported studies that evaluate, by incorporating a disease control group, whether neuropsychological performance in surgical patients changes beyond the variability of the assessment measures. To examine this issue, 17 PD patients were tested before and after bilateral STN stimulator implantation, both on and off stimulation.

Complications of deep brain stimulation surgery.

Although technological advances have reduced device-related complications, DBS surgery still carries a significant risk of transient and permanent complications. We report our experience in 86 patients and 149 DBS implants. Patients with Parkinson's disease, essential tremor and dystonia were treated.

Subthalamic nucleus stimulation in patients with a prior pallidotomy.

Object: A substantial number of patients with Parkinson disease (PD) who have undergone unilateral stereotactic pallidotomy ultimately develop symptom progression, becoming potential candidates for further surgical treatment. Bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) has been shown to be effective in the treatment of a subset of patients with refractory PD. Microelectrode recording is performed to help localize the STN and guide final placement of the electrode.

Neurophysiological modulation of the subthalamic nucleus by pallidal stimulation in Parkinson's disease.

Objectives: Current models of basal ganglia dysfunction in Parkinson's disease suggest a pivotal role of subthalamic nucleus (STN) hyperactivity. There is a direct excitatory output to the globus pallidus internus (GPi), which in turn hyperinhibits the motor thalamus and leads to a lack of cortical facilitation. The model, however, does not address the reciprocal influence of GPi on STN activity.

Neurophysiological refinement of subthalamic nucleus targeting.

Objective: Advances in image-guided stereotactic surgery, microelectrode recording techniques, and stimulation technology have been the driving forces behind a resurgence in the use of functional neurosurgery for the treatment of movement disorders. Despite the dramatic effects of deep brain stimulation (DBS) techniques in ameliorating the symptoms of Parkinson's disease, many critical questions related to the targeting, effects, and mechanisms of action of DBS remain unanswered. In this report, we describe the methods used to localize the subthalamic nucleus (STN) and we present the characteristics of encountered cells.

Comparison of anatomic and neurophysiological methods for subthalamic nucleus targeting.

Objective: The subthalamic nucleus (STN) has recently become the surgical target of choice for the treatment of medically refractory idiopathic Parkinson's disease. A number of anatomic and physiological targeting methods have been used to localize the STN. We retrospectively reviewed the various anatomic targeting methods and compared them with the final physiological target in 15 patients who underwent simultaneous bilateral STN implantation of deep brain stimulators.

Microelectrode recording during posteroventral pallidotomy: impact on target selection and complications.

Objective: To assess the practical usefulness of single-cell microelectrode recording (MER) when performing posteroventral pallidotomy.

Methods: A retrospective comparison of the initial, magnetic resonance imaging-derived coordinates of the pallidotomy target to the final, MER-refined lesion coordinates in 132 consecutive pallidotomies was conducted. The time required to perform the procedure and the surgical complications are reported.

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.

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 Parkinson's 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.

Left-right differences in motor thresholds after stimulation of the globus pallidus before pallidotomy.

Left-right upper limb motor threshold differences were found after electrical stimulation of the globus pallidus administered as a neuroprotective measure to avoid lesioning of the internal capsule during stereotactic pallidotomy for treatment of Parkinson's disease. Left sided stimulation resulted in lower thresholds in right handed patients compared with left handed patients. These differences were significant in women, but no significant differences were found in men.

Metabolic correlates of pallidal neuronal activity in Parkinson's disease.

We have used [18F]fluorodeoxyglucose and PET to identify specific metabolic covariance patterns associated with Parkinson's disease and related disorders previously. Nonetheless, the physiological correlates of these abnormal patterns are unknown. In this study we used PET to measure resting state glucose metabolism in 42 awake unmedicated Parkinson's disease patients prior to unilateral stereotaxic pallidotomy for relief of symptoms.

Stereotactic pallidotomy for Parkinson's disease: a long-term follow-up of unilateral pallidotomy.

Eleven patients suffering from Parkinson's 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.

Efficacy of bilateral pallidotomy.

Unilateral pallidotomy is a safe and effective treatment for medically refractory bradykinetic Parkinson's disease, especially in those patients with levodopa-induced dyskinesia and severe on-off fluctuations. The efficacy of bilateral pallidotomy is less certain. The authors completed 11 of 12 attempted bilateral pallidotomies among 150 patients undergoing pallidotomy at New York University.

Pallidal targeting with the COMPASS system.

The authors describe their initial experience with the new pallidotomy targeting software for the COMPASS system. As COMPASS permits window and contrast settings to be changed at any time, multiple imaging modalities can be employed for targeting. This feature allowed the incorporation of fast-spin echo/inversion recovery (FSE/IR) magnetic resonance images (MRI) into the planning protocol.

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.

Electrical stimulation of the globus pallidus preceding stereotactic posteroventral pallidotomy.

Physiological methods such as microelectrode recording of neuronal activity and electrical stimulation of target structures can improve the safety and efficacy of certain stereotactic surgeries. The globus pallidus (GP) was electrically stimulated in 136 patients with Parkinson's disease prior to unilateral posteroventral pallidotomy to identify functional areas and prevent deficits. We found that electrical stimulation of the GP elicited two principal responses: contractions of the contralateral hand and flashing lights.

[Activity and function of neurons in the globus pallidus in Parkinson's disease].

We investigated the activity and functional distribution of globus pallidus neurons in Parkinson's disease patients and recorded single cell activity of globus pallidus medialis and changes related to the movements of different joints in 31 patients during stereotactic ventral pallidotomy procedure. We showed that discharge rates of 19% of medial globus pallidus neurons were modulated by passive contralateral movements; 77.2% of these pallidal units showed changes related solely to single joint movement and 22.

Stereotactic ventral pallidotomy for Parkinson's disease.

Eighteen patients with medically intractable Parkinson's disease that was characterized by bradykinesia, rigidity, and marked "on-off" fluctuations underwent stereotactic ventral pallidotomy under local anesthesia. Targeting was aided by anatomic coordinates derived from the MRI, intraoperative cell recordings, and electrical stimulation prior to lesioning. A nonsurgically treated group of seven similarly affected individuals was also followed.

Anatomic and physiological considerations in pallidotomy for Parkinson's disease.

Our ongoing study of ventral pallidotomy for the control of Parkinson's 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.