Effects of deep brain stimulation target on the activation and suppression of action impulses.

OBJECTIVE: Deep brain stimulation (DBS) is an effective treatment to improve motor symptoms in Parkinson's disease (PD). The Globus Pallidus (GPi) and the Subthalamic Nucleus (STN) are the most targeted brain regions for stimulation and produce similar improvements in PD motor symptoms. However, our understanding of stimulation effects across targets on inhibitory action control processes is limited. We compared the effects of STN (n = 20) and GPi (n = 13) DBS on inhibitory control in PD patients. METHODS: We recruited PD patients undergoing DBS at the Vanderbilt Movement Disorders Clinic and measured their performance on an inhibitory action control task (Simon task) before surgery (optimally treated medication state) and after surgery in their optimally treated state (medication plus their DBS device turned on). RESULTS: DBS to both STN and GPi targets induced an increase in fast impulsive errors while simultaneously producing more proficient reactive suppression of interference from action impulses. CONCLUSIONS: Stimulation in GPi produced similar effects as STN DBS, indicating that stimulation to either target increases the initial susceptibility to act on strong action impulses while concomitantly improving the ability to suppress ongoing interference from activated impulses. SIGNIFICANCE: Action impulse control processes are similarly impacted by stimulating dissociable nodes in frontal-basal ganglia circuitry.

Developing Predictor Models of Postoperative Verbal Fluency After Deep Brain Stimulation Using Preoperative Neuropsychological Assessment.

BACKGROUND: Deep brain stimulation (DBS) for Parkinson disease provides significant improvement of motor symptoms but can also produce neurocognitive side effects. A decline in verbal fluency (VF) is among the most frequently reported side effects. Preoperative factors that could predict VF decline have yet to be identified. OBJECTIVE: To develop predictive models of DBS postoperative VF decline using a machine learning approach. METHODS: We used a prospective database of patients who underwent neuropsychological and VF assessment before both subthalamic nucleus (n = 47, bilateral = 44) and globus pallidus interna (n = 43, bilateral = 39) DBS. We used a neurobehavioral rating profile as features for modeling postoperative VF. We constructed separate models for action, semantic, and letter VF. We used a leave-one-out scheme to test the accuracy of the predictive models using median absolute error and correlation with actual postoperative scores. RESULTS: The predictive models were able to predict the 3 types of VF with high accuracy ranging from a median absolute error of 0.92 to 1.36. Across all three models, higher preoperative fluency, digit span, education, and Mini-Mental State Examination were predictive of higher postoperative fluency scores. By contrast, higher frontal system deficits, age, Questionnaire for Impulsive-Compulsive Disorders in Parkinson's disease scored by the patient, disease duration, and Behavioral Inhibition/Behavioral Activation Scale scores were predictive of lower postoperative fluency scores. CONCLUSION: Postoperative VF can be accurately predicted using preoperative neurobehavioral rating scores above and beyond preoperative VF score and relies on performance over different aspects of executive function.

Essential tremor impairs the ability to suppress involuntary action impulses.

Essential tremor (ET) is a movement disorder characterized primarily by action tremor which affects the regulation of movements. Disruptions in cerebello-thalamocortical networks could interfere with cognitive control over actions in ET, for example, the ability to suppress a strong automatic impulse over a more appropriate action (conflict control). The current study investigated whether ET impacts conflict control proficiency. Forty-one ET patients and 29 age-matched healthy controls (HCs) performed a conflict control task (Simon task). Participants were instructed to give a left or right response to a spatially lateralized arrow (direction of the arrow). When the action signaled by the spatial location and direction of the arrow were non-corresponding (induced conflict), the inappropriate action impulse required suppression. Overall, ET patients responded slower and less accurately compared to HCs. ET patients were especially less accurate on non-corresponding conflict (Nc) versus corresponding (Cs) trials. A focused analysis on fast impulsive response rates (based on the accuracy rate at the fastest reaction times on Nc trials) showed that ET patients made more fast errors compared to HCs. Results suggest impaired conflict control in ET compared to HCs. The increased impulsive errors seen in the ET population may be a symptom of deficiencies in the cerebello-thalamocortical networks, or, be caused by indirect effects on the cortico-striatal pathways. Future studies into the functional networks impacted by ET (cortico-striatal and cerebello-thalamocortical pathways) could advance our understanding of inhibitory control in general and the cognitive deficits in ET.

Noninvasive Thalamotomy for Refractory Tremor by Frameless Radiosurgery.

PURPOSE: We sought to determine whether a more widely accessible, noninvasive, frameless approach to radiosurgical thalamotomy would improve objective measures of refractory essential or parkinsonian tremor without added toxicity compared with reports of frame-based radiosurgery. METHODS AND MATERIALS: We conducted a single-arm pilot observational prospective trial of adult patients with essential or parkinsonian tremor from 2013 to 2019 and report results at 1-year follow-up. Patients were treated with frameless unilateral radiosurgical ablation of the thalamic ventral intermediate nucleus to a maximum dose of 160 Gy. Treatment response was measured by the Fahn-Tolosa-Marin (FTM) tremor rating scale and the Quality of Life in Essential Tremor or Parkinson's Disease Questionnaire obtained before treatment and at 3, 6, 9, and 12 months. RESULTS: Thirty-three patients, including 23 with essential tremor and 10 with Parkinson's disease, were enrolled. Overall treatment response rate per FTM was 83% (15 of 18) at 6 months. There was a marked improvement in tremor, with an average total FTM reduction of 21% at 3 months (from 46 to 30 points; P = .003) and 41% at 6 months (from 46 to 24 points; P = .001). At 6 months, functional decline had regressed by 54% (from 15 to 7 points; P = .001). Quality of life improved by 57% (P = .001) at 6 months in patients with essential tremor, and patients with Parkinson's disease had unchanged quality of life. At 1-year follow-up, grade 2 neurologic adverse events were observed in 6% (2 of 33) of patients without any grade ≥ 3 events. CONCLUSION: Noninvasive, frameless radiosurgical thalamotomy may be a feasible treatment for patients with refractory tremor and demonstrates short-term safety at 1-year follow-up. This pilot study provides promising preliminary descriptions of efficacy, and definitive estimates of long-term safety and benefit require further study with longer follow-up.

Long-Term Care Resident Awareness and Interest in Spasticity Treatments.

Spasticity is common in long-term care settings (affecting up to one in three residents), yet it remains under-treated despite safe and effective, Food and Drug Administration (FDA)-approved therapies. One barrier to treatment may be lack of awareness of available therapies for long-term care residents living with spasticity. A standardized spasticity treatment awareness and interest interview was conducted with 18 nursing home residents and 11 veterans' home residents in this cross-sectional study. Veterans' home residents were also asked about potential barriers to receiving spasticity treatment. Many residents across both long-term care facilities were unaware of most of the treatment options for spasticity. Participants were most aware of physical/occupational therapy (83%, 95% CI: 65-93%) and least aware of intrathecal baclofen (21%, 95% CI: 9-39%). After learning about treatments, only 7% of participants (95% CI: 0-23%) were not interested in receiving any form of spasticity treatment. Among residents previously unaware of spasticity treatments, at least one quarter became interested in receiving treatment and at least one-fifth indicated possibly being interested in the treatment after learning about it. Potential barriers to receiving treatment included traveling to see a doctor and limited knowledge of insurance coverage of spasticity treatments. These results suggest that patient-centered approaches, including education and discerning patient preferences, may improve spasticity treatment in long-term care settings.

Deep brain stimulation effects on verbal fluency dissociated by target and active contact location.

OBJECTIVE: Deep brain stimulation (DBS) improves motor symptoms in Parkinson's disease (PD), but it can also disrupt verbal fluency with significant costs to quality of life. The current study investigated how variability of bilateral active electrode coordinates along the superior/inferior, anterior/posterior, and lateral/medial axes in the subthalamic nucleus (STN) or the globus pallidus interna (GPi) contribute to changes in verbal fluency. We predicted that electrode location in the left hemisphere would be linked to changes in fluency, especially in the STN. METHODS: Forty PD participants treated with bilateral DBS targeting STN (n = 23) or GPi (n = 17) completed verbal fluency testing in their optimally treated state before and after DBS therapy. Normalized atlas coordinates from left and right active electrode positions along superior/inferior, anterior/posterior, and lateral/medial axes were used to predict changes in fluency postoperatively, separately for patients with STN and GPi targets. RESULTS: Consistent with prior studies, fluency significantly declined pre- to postsurgery (in both DBS targets). In STN-DBS patients, electrode position along the inferior to superior axis in the left STN was a significant predictor of fluency changes; relatively more superior left active electrode was associated with the largest fluency declines in STN. Electrode coordinates in right STN or GPi (left or right) did not predict fluency changes. INTERPRETATION: We discuss these findings in light of putative mechanisms and potential clinical impact.

A comparative evaluation of telehealth and direct assessment when screening for spasticity in residents of two long-term care facilities.

OBJECTIVE: To evaluate the performance of telehealth as a screening tool for spasticity compared to direct patient assessment in the long-term care setting. DESIGN: Cross-sectional, observational study. SETTING: Two long-term care facilities: a 140-bed veterans' home and a 44-bed state home for individuals with intellectual and developmental disabilities. SUBJECTS: Sixty-one adult residents of two long-term care facilities (aged 70.1 ± 16.2 years) were included in this analysis. Spasticity was identified in 43% of subjects (Modified Ashworth Scale rating mode = 2). Contributing diagnoses included traumatic brain injury, spinal cord injury, birth trauma, stroke, cerebral palsy, and multiple sclerosis. MAIN MEASURES: Movement disorders neurologists conducted in-person examinations to determine whether spasticity was present (reference standard) and also evaluated subjects with spasticity using the Modified Ashworth Scale. Telehealth screening examinations, facilitated by a bedside nurse, were conducted remotely by two teleneurologists using a three-question screening tool. Telehealth screening determinations of spasticity were compared to the reference standard determination to calculate sensitivity, specificity, and the area under the curve (AUC) in receiver operating characteristics. Teleneurologist agreement was evaluated using Cohen's kappa. RESULTS: Teleneurologist 1 had a specificity of 89% and sensitivity of 65% to identify the likely presence of spasticity (n = 61; AUC = 0.770). Teleneurologist 2 showed 100% specificity and 82% sensitivity (n = 16; AUC = 0.909). There was almost perfect agreement between the two examiners at 94% (kappa = 0.875, 95% CI: 0.640-1.000). CONCLUSION: Telehealth may provide a useful, efficient method of identifying residents of long-term care facilities that likely need referral for spasticity evaluation.

Subthalamic Nucleus Subregion Stimulation Modulates Inhibitory Control.

Patients with Parkinson's disease (PD) often experience reductions in the proficiency to inhibit actions. The motor symptoms of PD can be effectively treated with deep brain stimulation (DBS) of the subthalamic nucleus (STN), a key structure in the frontal-striatal network that may be directly involved in regulating inhibitory control. However, the precise role of the STN in stopping control is unclear. The STN consists of functional subterritories linked to dissociable cortical networks, although the boundaries of the subregions are still under debate. We investigated whether stimulating the dorsal and ventral subregions of the STN would show dissociable effects on ability to stop. We studied 12 PD patients with STN DBS. Patients with two adjacent contacts positioned within the bounds of the dorsal and ventral STN completed two testing sessions (OFF medication) with low amplitude stimulation (0.4 mA) at either the dorsal or ventral contacts bilaterally, while performing the stop task. Ventral, but not dorsal, DBS improved stopping latencies. Go reactions were similar between dorsal and ventral DBS STN. Stimulation in the ventral, but not dorsal, subregion of the STN improved stopping speed, confirming the involvement of the STN in stopping control and supporting the STN functional subregions.

Deep brain stimulation in early-stage Parkinson disease: Five-year outcomes.

OBJECTIVE: To report 5-year outcomes from the subthalamic nucleus (STN) deep brain stimulation (DBS) in early-stage Parkinson disease (PD) pilot clinical trial. METHODS: The pilot was a prospective, single-blind clinical trial that randomized patients with early-stage PD (Hoehn & Yahr II off medications) to receive bilateral STN DBS plus optimal drug therapy (ODT) vs ODT alone (IDEG050016, NCT0282152, IRB040797). Participants who completed the 2-year trial participated in this observational follow-up study, which included annual outpatient visits through 5 years. This analysis includes 28 patients who were taking PD medications for 6 months to 4 years at enrollment. Outcomes were analyzed using both proportional odds logistic regression and linear mixed effects models. RESULTS: Early STN DBS + ODT participants required lower levodopa equivalent daily doses (p = 0.04, ß = -240 mg, 95% confidence interval [CI] -471 to -8) and had 0.06 times the odds of requiring polypharmacy at 5 years compared to early ODT participants (p = 0.01, odds ratio [OR] 0.06, 95% CI 0.00 to 0.65). The odds of having worse rest tremor for early STN DBS + ODT participants were 0.21 times those of early ODT participants (p < 0.001, OR 0.21, 95% CI 0.09 to 0.45). The safety profile was similar between groups. CONCLUSIONS: These results suggest that early DBS reduces the need for and complexity of PD medications while providing long-term motor benefit over standard medical therapy. Further investigation is warranted, and the Food and Drug Administration has approved the conduct of a prospective, multicenter, pivotal clinical trial of DBS in early-stage PD (IDEG050016). CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that DBS implanted in early-stage PD decreases the risk of disease progression and polypharmacy compared to optimal medical therapy alone.

Subthalamic nucleus deep brain stimulation with a multiple independent constant current-controlled device in Parkinson's disease (INTREPID): a multicentre, double-blind, randomised, sham-controlled study.

BACKGROUND: Deep brain stimulation (DBS) of the subthalamic nucleus is an established therapeutic option for managing motor symptoms of Parkinson's disease. We conducted a double-blind, sham-controlled, randomised controlled trial to assess subthalamic nucleus DBS, with a novel multiple independent contact current-controlled (MICC) device, in patients with Parkinson's disease. METHODS: This trial took place at 23 implanting centres in the USA. Key inclusion criteria were age between 22 and 75 years, a diagnosis of idiopathic Parkinson's disease with over 5 years of motor symptoms, and stable use of anti-parkinsonian medications for 28 days before consent. Patients who passed screening criteria were implanted with the DBS device bilaterally in the subthalamic nucleus. Patients were randomly assigned in a 3:1 ratio to receive either active therapeutic stimulation settings (active group) or subtherapeutic stimulation settings (control group) for the 3-month blinded period. Randomisation took place with a computer-generated data capture system using a pre-generated randomisation table, stratified by site with random permuted blocks. During the 3-month blinded period, both patients and the assessors were masked to the treatment group while the unmasked programmer was responsible for programming and optimisation of device settings. The primary outcome was the difference in mean change from baseline visit to 3 months post-randomisation between the active and control groups in the mean number of waking hours per day with good symptom control and no troublesome dyskinesias, with no increase in anti-parkinsonian medications. Upon completion of the blinded phase, all patients received active treatment in the open-label period for up to 5 years. Primary and secondary outcomes were analysed by intention to treat. All patients who provided informed consent were included in the safety analysis. The open-label phase is ongoing with no new enrolment, and current findings are based on the prespecified interim analysis of the first 160 randomly assigned patients. The study is registered with ClinicalTrials.gov, NCT01839396. FINDINGS: Between May 17, 2013, and Nov 30, 2017, 313 patients were enrolled across 23 sites. Of these 313 patients, 196 (63%) received the DBS implant and 191 (61%) were randomly assigned. Of the 160 patients included in the interim analysis, 121 (76%) were randomly assigned to the active group and 39 (24%) to the control group. The difference in mean change from the baseline visit (post-implant) to 3 months post-randomisation in increased ON time without troublesome dyskinesias between the active and control groups was 3·03 h (SD 4·52, 95% CI 1·3-4·7; p<0·0001). 26 serious adverse events in 20 (13%) patients occurred during the 3-month blinded period. Of these, 18 events were reported in the active group and 8 in the control group. One death was reported among the 196 patients before randomisation, which was unrelated to the procedure, device, or stimulation. INTERPRETATION: This double-blind, sham-controlled, randomised controlled trial provides class I evidence of the safety and clinical efficacy of subthalamic nucleus DBS with a novel MICC device for the treatment of motor symptoms of Parkinson's disease. Future trials are needed to investigate potential benefits of producing a more defined current field using MICC technology, and its effect on clinical outcomes. FUNDING: Boston Scientific.

Prevalence of Spasticity in Nursing Home Residents.

OBJECTIVES: To determine the prevalence, rate of underdiagnosis and undertreatment, and association with activities of daily living dependency of spasticity in a nursing home setting. DESIGN: Cross-sectional study. SETTING AND PARTICIPANTS: This study is an analysis of a deidentified data set generated by a prior quality improvement project at a 240-bed nursing home for residents receiving long-term care or skilled nursing care services. METHODS: Each resident was examined by a movement disorders specialist neurologist to determine whether spasticity was present and, if so, the total number of spastic postures present in upper and lower limbs was recorded. Medical records, including the Minimum Data Set, were reviewed for neurologic diagnoses associated with spasticity, activities of daily living (ADL) dependency, and prior documentation of diagnosis and past or current treatments. Ordinary least squares linear regression models were used to evaluate the association between spasticity and ADL dependency. RESULTS: Two hundred nine residents (154 women, 81.9 ± 10.9 years) were included in this analysis. Spasticity was present in 22% (45/209) of residents examined by the neurologist. Only 11% of residents (5/45) had a prior diagnosis of spasticity and were receiving treatment. Presence of spasticity was associated with greater ADL dependency (χ2 = 51.72, P < .001), which was driven by lower limb spasticity (χ2 = 14.56, P = .006). CONCLUSIONS AND IMPLICATIONS: These results suggest that spasticity (1) is common in nursing homes (1 of 5 residents), (2) is often not diagnosed or adequately treated, and (3) is associated with worse ADL dependency. Further research is needed to enhance the rates of diagnosis and treatment of spasticity in long-term care facilities.

Action Control Deficits in Patients With Essential Tremor.

OBJECTIVES: Essential tremor (ET) is a movement disorder characterized by action tremor which impacts motor execution. Given the disrupted cerebellar-thalamo-cortical networks in ET, we hypothesized that ET could interfere with the control mechanisms involved in regulating motor performance. The ability to inhibit or stop actions is critical for navigating many daily life situations such as driving or social interactions. The current study investigated the speed of action initiation and two forms of action control, response stopping and proactive slowing in ET. METHODS: Thirty-three ET patients and 25 healthy controls (HCs) completed a choice reaction task and a stop-signal task, and measures of going speed, proactive slowing and stop latencies were assessed. RESULTS: Going speed was significantly slower in ET patients (649 ms) compared to HCs (526 ms; F(1,56) = 42.37; p <.001; η 2 = .43), whereas proactive slowing did not differ between groups. ET patients exhibited slower stop signal reaction times (320 ms) compared to HCs (258 ms, F(1,56) = 15.3; p <.00; η 2 = .22) and more severe motor symptoms of ET were associated with longer stopping latencies in a subset of patients (Spearman rho = .48; p <.05). CONCLUSIONS: In line with previous studies, ET patients showed slower action initiation. Additionally, inhibitory control was impaired whereas proactive slowing remained intact relative to HCs. More severe motor symptoms of ET were associated with slower stopping speed, and may reflect more progressive changes to the cerebellar-thalamo-cortical network. Future imaging studies should specify which structural and functional changes in ET can explain changes in inhibitory action control. (JINS, 2019, 25, 156-164).

Confined Thalamic Deep Brain Stimulation in Refractory Essential Tremor.

BACKGROUND: Thalamic ventral intermediate nucleus (VIM) deep brain stimulation (DBS) is an effective therapy for medication-refractory essential tremor (ET). However, 13-40% of patients with an initially robust tremor efficacy lose this benefit over time despite reprogramming attempts. At our institution, a cohort of ET patients with VIM DBS underwent implantation of a second anterior (ventralis oralis anterior; VOA) DBS lead to permit "confined stimulation." We sought to assess whether confined stimulation conferred additional tremor capture compared to VIM or VOA stimulation alone. METHODS: Seven patients participated in a protocol-based programming session during which a video-recorded Fahn-Tolosa-Marin Part A (FTM-A) tremor rating scale was used in the following 4 DBS states: off stimulation, VIM stimulation alone, VOA stimulation alone, and dual lead (confined) stimulation. RESULTS: The average (SD) baseline FTM-A off score was 17.6 (4.0). VIM stimulation alone lowered the average FTM-A total score to 6.9 (4.0). Confined stimulation further attenuated the tremor, reducing the total score to 5.7 (2.8). CONCLUSIONS: Confined thalamic DBS can provide additional symptomatic benefits in patients with unsatisfactory tremor control from VIM or VOA stimulation alone.

Effects of deep brain stimulation on rest tremor progression in early stage Parkinson disease.

OBJECTIVE: To evaluate whether the progression of individual motor features was influenced by early deep brain stimulation (DBS), a post hoc analysis of Unified Parkinson's Disease Rating Scale-III (UPDRS-III) score (after a 7-day washout) was conducted from the 2-year DBS in early Parkinson disease (PD) pilot trial dataset. METHODS: The prospective pilot trial enrolled patients with PD aged 50-75 years, treated with PD medications for 6 months-4 years, and no history of dyskinesia or other motor fluctuations, who were randomized to receive optimal drug therapy (ODT) or DBS plus ODT (DBS + ODT). At baseline and 6, 12, 18, and 24 months, all patients stopped all PD therapy for 1 week (medication and stimulation, if applicable). UPDRS-III "off" item scores were compared between the ODT and DBS + ODT groups (n = 28); items with significant between-group differences were analyzed further. RESULTS: UPDRS-III "off" rest tremor score change from baseline to 24 months was worse in patients receiving ODT vs DBS + ODT (p = 0.002). Rest tremor slopes from baseline to 24 months favored DBS + ODT both "off" and "on" therapy (p < 0.001, p = 0.003, respectively). More ODT patients developed new rest tremor in previously unaffected limbs than those receiving DBS + ODT (p = 0.001). CONCLUSIONS: These results suggest the possibility that DBS in early PD may slow rest tremor progression. Future investigation in a larger cohort is needed, and these findings will be tested in the Food and Drug Administration-approved, phase III, pivotal, multicenter clinical trial evaluating DBS in early PD. CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that for patients with early PD, DBS may slow the progression of rest tremor.

Subthalamic Nucleus Deep Brain Stimulation May Reduce Medication Costs in Early Stage Parkinson's Disease.

BACKGROUND: Subthalamic nucleus deep brain stimulation (STN-DBS) is well-known to reduce medication burden in advanced stage Parkinson's disease (PD). Preliminary data from a prospective, single blind, controlled pilot trial demonstrated that early stage PD subjects treated with STN-DBS also required less medication than those treated with optimal drug therapy (ODT). OBJECTIVE: The purpose of this study was to analyze medication cost and utilization from the pilot trial of DBS in early stage PD and to project 10 year medication costs. METHODS: Medication data collected at each visit were used to calculate medication costs. Medications were converted to levodopa equivalent daily dose, categorized by medication class, and compared. Medication costs were projected to advanced stage PD, the time when a typical patient may be offered DBS. RESULTS: Medication costs increased 72% in the ODT group and decreased 16% in the DBS+ODT group from baseline to 24 months. This cost difference translates into a cumulative savings for the DBS+ODT group of $7,150 over the study period. Projected medication cost savings over 10 years reach $64,590. Additionally, DBS+ODT subjects were 80% less likely to require polypharmacy compared with ODT subjects at 24 months (p <  0.05; OR = 0.2; 95% CI: 0.04-0.97). CONCLUSIONS: STN-DBS in early PD reduced medication cost over the two-year study period. DBS may offer substantial long-term reduction in medication cost by maintaining a simplified, low dose medication regimen. Further study is needed to confirm these findings, and the FDA has approved a pivotal, multicenter clinical trial evaluating STN-DBS in early PD.

Generalized motor inhibitory deficit in Parkinson's disease patients who freeze.

Freezing of gait is a disabling symptom of Parkinson's disease (PD) that involves failure to initiate and continue motor activity appropriately. PD disrupts fronto-basal ganglia circuitries that also implement the inhibition of responses, leading to the hypothesis that freezing of gait may involve fundamental changes in both initiation and inhibition of motor actions. We asked whether PD patients who show freezing of gait show selective deficits in their ability to inhibit upper and lower extremity reactions. We compared older healthy controls, older PD controls without freezing of gait, and older PD participants with freezing of gait, in stop-signal tasks that measured the initiation (go trials) and inhibition (stop trials) of both hand and foot responses. When only go trials were presented, all three groups showed similar initiation speeds across lower and upper extremity responses. When stop-signal trials were introduced, both PD groups slowed their reactions nearly twice as much as healthy controls. While this adjustment helped PD controls stop their actions as quickly as healthy controls, PD patients with freezing showed significantly delayed inhibitory control of both upper and lower extremities. When anticipating the need to stop their actions urgently, PD patients show greater adjustments (i.e., slowing) to reaction speed than healthy controls. Despite these proactive adjustments, PD patients who freeze show marked impairments in inhibiting both upper and lower extremity responses, suggesting that freezing may involve a fundamental disruption to the brain's inhibitory control system.

Deep brain stimulation may reduce the relative risk of clinically important worsening in early stage Parkinson's disease.

BACKGROUND: The Vanderbilt pilot trial of deep brain stimulation (DBS) in early Parkinson's disease (PD) enrolled patients on medications six months to four years without motor fluctuations or dyskinesias. We conducted a patient-centered analysis based on clinically important worsening of motor symptoms and complications of medical therapy for all subjects and a subset of subjects with a more focused medication duration. Continuous outcomes were also analyzed for this focused cohort. METHODS: A post hoc analysis was conducted on all subjects from the pilot and a subset of subjects taking PD medications 1-4 years at enrollment. Clinically important worsening is defined as both a ≥ 3 point increase in UPDRS Part III and a ≥ 1 point increase in Part IV. RESULTS: DBS plus optimal drug therapy (DBS + ODT) subjects experienced a 50-80% reduction in the relative risk of worsening after two years. The DBS + ODT group was improved compared to optimal drug therapy (ODT) at each time point on Total UPDRS and Part III (p = 0.04, p = 0.02, respectively, at 24 months). Total UPDRS, Part IV, and PDQ-39 scores significantly worsened in the ODT group after two years (p < 0.003), with no significant change in the DBS + ODT group. CONCLUSIONS: DBS + ODT in early PD may reduce the risk of clinically important worsening. These findings further confirm the need to determine if DBS + ODT is superior to medical therapy for managing symptoms, reducing the complications of medications, and improving quality of life. The FDA has approved the conduct of a large-scale, pivotal clinical trial of DBS in early stage PD.

Neuropsychological effects of deep brain stimulation in subjects with early stage Parkinson's disease in a randomized clinical trial.

BACKGROUND: Deep brain stimulation (DBS) is an effective treatment for patients with advanced Parkinson's disease (PD) and motor symptom complications. Recently, attention has been focused on whether offering DBS earlier in the course of PD is beneficial. OBJECTIVE: The purpose of this study was to determine the effects of DBS on neuropsychological functioning in subjects with early stage PD. METHODS: Thirty subjects with early PD (Hoehn & Yahr Stage II off medication) were randomized to optimal drug therapy (ODT) (n = 15) or bilateral subthalamic nucleus (STN) DBS+ODT (n = 15) after completing an expanded informed consent process specially designed for the study and administered by a medical ethicist and the study team. Comprehensive neuropsychological testing was completed in the treatment-withdrawn state at baseline and at 12 month and 24 month follow-ups. RESULTS: Two serious adverse events occurred in the DBS+ODT group. One subject experienced a stroke and another developed infected hardware that contributed to specific declines in cognitive functioning. However, compared to the ODT group, the remaining subjects in the DBS+ODT group exhibited modest reductions on a few measures of attention, executive function, and word fluency at 12 months. These differences were largely diminished at 24 months, especially when those with the adverse events were excluded. CONCLUSIONS: The results of this trial provide novel data regarding the effects of DBS on cognitive function in early PD. We believe that the findings and insights from this trial can help guide the safety analysis and risk-benefit evaluations in future discussions of DBS in early stage PD.

Use of efficacy probability maps for the post-operative programming of deep brain stimulation in essential tremor.

INTRODUCTION: Post-operative programming of deep brain stimulation for movement disorders can be both time consuming and difficult, which can delay the optimal symptom control for the patient. Probabilistic maps of stimulation response could improve programming efficiency and optimization. METHODS: The clinically selected contacts of patients who had undergone ventral intermediate nucleus deep brain stimulation for the treatment of essential tremor at our institution were compared against contacts selected based on a probability map of symptom reduction built by populating data from a number of patients using non-rigid image registration. A subgroup of patients whose clinical contacts did not match the map-based selections prospectively underwent a tremor rating scale evaluation to compare the symptom relief achieved by the two options. Both the patient and video reviewer were blinded to the selection. RESULTS: 54% of the map-based and clinical contacts were an exact match retrospectively and were within one contact 83% of the time. In 5 of the 8 mismatched leads that were evaluated prospectively in a double blind fashion, the map-based contact showed equivalent or better tremor improvement than the clinically active contact. CONCLUSIONS: This study suggests that probability maps of stimulation responses can assist in selecting the clinically optimal contact and increase the efficiency of programming.

Subthalamic nucleus deep brain stimulation in early stage Parkinson's disease.

BACKGROUND: Deep brain stimulation (DBS) is an effective and approved therapy for advanced Parkinson's disease (PD), and a recent study suggests efficacy in mid-stage disease. This manuscript reports the results of a pilot trial investigating preliminary safety and tolerability of DBS in early PD. METHODS: Thirty subjects with idiopathic PD (Hoehn & Yahr Stage II off medication), age 50-75, on medication ≥6 months but ≤4 years, and without motor fluctuations or dyskinesias were randomized to optimal drug therapy (ODT) (n = 15) or DBS + ODT (n = 15). Co-primary endpoints were the time to reach a 4-point worsening from baseline in the UPDRS-III off therapy and the change in levodopa equivalent daily dose from baseline to 24 months. RESULTS: As hypothesized, the mean UPDRS total and part III scores were not significantly different on or off therapy at 24 months. Medication requirements in the DBS + ODT group were lower at all time points with a maximal difference at 18 months. With a few exceptions, differences in neuropsychological functioning were not significant. Two subjects in the DBS + ODT group suffered serious adverse events; remaining adverse events were mild or transient. CONCLUSIONS: This study demonstrates that subjects with early stage PD will enroll in and complete trials testing invasive therapies and provides preliminary evidence that DBS is well tolerated in early PD. The results of this trial provide the data necessary to design a large, phase III, double-blind, multicenter trial investigating the safety and efficacy of DBS in early PD.