Comprehensive, Multidisciplinary Deep Brain Stimulation Screening for Parkinson Patients: No Room for "Short Cuts"

Individualized Structural Perturbations on Normative Brain Connectome Restrict Deep Brain Stimulation Outcomes in Parkinson's Disease

BACKGROUND

Patients with Parkinson's disease (PD) respond to deep brain stimulation (DBS) variably. However, how brain substrates restrict DBS outcomes remains unclear.

OBJECTIVE

In this article, we aim to identify prognostic brain signatures for explaining the response variability.

METHODS

We retrospectively investigated a cohort of patients with PD (n = 141) between 2017 and 2022, and defined DBS outcomes as the improvement ratio of clinical motor scores. We used a deviation index to quantify individual perturbations on a reference structural covariance network acquired with preoperative T1-weighted magnetic resonance imaging. The neurobiological perturbations of patients were represented as z scored indices based on the chronological perturbations measured on a group of normal aging adults.

RESULTS

After applying stringent statistical tests (z > 2.5) and correcting for false discoveries (P < 0.01), we found that accelerated deviations mainly affected the prefrontal cortex, motor strip, limbic system, and cerebellum in PD. Particularly, a negative network within the accelerated deviations, expressed as "more preoperative deviations, less postoperative improvements," could predict DBS outcomes (mean absolute error = 0.09, R2 = 0.15). Moreover, a fusion of personal brain predictors and medical responses significantly improved traditional evaluations of DBS outcomes. Notably, the most important brain predictor, a pathway connecting the cognitive unit (prefrontal cortex) and motor control unit (cerebellum and motor strip), partially mediates DBS outcomes with the age at surgery.

CONCLUSIONS

Our findings suggest that individual structural perturbations on the cognitive motor control circuit are critical for modulating DBS outcomes. Interventions toward the circuit have the potential for additional clinical improvements. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Reverse Visually Guided Reaching in Patients with Parkinson’s Disease

In addition to motor symptoms such as difficulty in movement initiation and bradykinesia, patients with Parkinson’s disease (PD) display nonmotor executive cognitive dysfunction with deficits in inhibitory control. Preoperative psychological assessments are used to screen for impulsivity that may be worsened by deep brain stimulation (DBS) of the subthalamic nucleus (STN). However, it is unclear whether anti-Parkinson’s therapy, such as dopamine replacement therapy (DRT) or DBS, which has beneficial effects on motor function, adversely affects inhibitory control or its domains. The detrimental effects of STN-DBS are more apparent when tasks test the inhibition of habitual prepotent responses or involve complex cognitive loads. Our goal was to use a reverse visually guided reaching (RVGR) task, a hand-based version of the antisaccade task, to simultaneously measure motor performance and response inhibition in subjects with PD. We recruited 55 healthy control subjects, 26 PD subjects receiving treatment with DRTs, and 7 PD subjects receiving treatment with STN-DBS and DRTs. In the RVGR task, a cursor moved opposite to the subject’s hand movement. This was compared to visually guided reaching (VGR) where the cursor moved in the same direction as the subject’s hand movement. Reaction time, mean speed, and direction errors (in RVGR) were assessed. Reaction times were longer, and mean speeds were slower during RVGR compared to VGR in all three groups but worse in untreated subjects with PD. Treatment with DRTs, DBS, or DBS + DRT improved the reaction time and speed on the RVGR task to a greater extent than VGR. Additionally, DBS or DBS + DRT demonstrated an increase in direction errors, which was correlated with decreased reaction time. These results show that the RVGR task quantifies the benefit of STN-DBS on bradykinesia and the concomitant reduction of proactive inhibitory control. The RVGR task has the potential to be used to rapidly screen for preoperative deficits in inhibitory control and to titrate STN-DBS, to maximize the therapeutic benefits on movement, and minimize impaired inhibitory control.

Utility of routine surface electrophysiology to screen for functional tremor prior to surgical treatment of essential tremor

Background

Patients with functional tremor may be clinically misdiagnosed as “medication-refractory” essential tremor (ET) and referred for surgical treatment. Electrophysiology can screen for functional tremor and avoid inappropriate surgery.

Objective

To report the utility of surface electrophysiology (SEMG) to screen for functional tremor in patients referred for ET surgery.

Methods

Retrospective review of consecutive ET patients referred to the Mayo Clinic DBS clinic over 1.5 years. Included subjects had a clinical diagnosis of medication-refractory ET and completed presurgical workup including routine SEMG tremor study.

Results

Of 87 subjects, 9 (10%) were clinically suspected of functional tremor by the DBS neurologist. Electrophysiology confirmed functional tremor features in 7/9 and ET in the other 2/9; and newly identified 5 additional cases of functional tremor. There were 12 total confirmed cases of functional tremor: isolated in 1, and mixed functional tremor and ET in 11. Of 11 mixed patients, 6 with mild functional overlay were approved for surgery. The remaining 5 patients with moderate-severe functional overlay and the single patient with isolated functional tremor were referred to the functional tremor motor retraining program. Of these, 1 patient with mixed tremor had residual disabling organic ET after program completion and was later approved for surgery. Thus, 5/87 patients (6%) avoided unnecessary surgery.

Conclusions

Functional tremor may frequently overlay “medication-refractory” ET amongst patients referred for surgery, affecting 1 of 7 patients in our quaternary referral DBS center. Electrophysiology studies are useful to routinely screen patients and prevent unnecessary surgery.

Subcortical Iron Accumulation Pattern May Predict Neuropsychological Outcomes After Subthalamic Nucleus Deep Brain Stimulation: A Pilot Study

BACKGROUND:

Neuropsychological outcomes after deep brain stimulation (DBS) are variable and may arise from the heterogeneous neuropathological processes in Parkinson’s disease (PD).

OBJECTIVE:

To explore if brain iron accumulation patterns and its region-specific alterations relate to neuropsychological outcomes post-DBS.

METHODS:

Thirty-two PD subjects were identified from our database with susceptibility MRI prior to bilateral subthalamic nucleus (STN) DBS between 2011–2016. Demographic (age, sex, education), clinical information (disease duration, neuropsychological scores), and R2* (susceptibility MRI measure reflecting iron) in 11 subcortical regions of interest were obtained. Neuropsychological outcomes were defined as changes in psychomotor speed, executive function, attention, memory, and depression by subtracting pre- and post-DBS scores. A penalized logistic analysis was used to identify the best pre-DBS clinical and R2* predictors for each neuropsychological domain. Pearson’s partial correlations explored R2* associations with neuropsychological outcomes.

RESULTS:

Combined clinical and MRI metrics were associated better with neuropsychological outcomes (R²≥0.373, p-value≤0.008) than either alone. Adding R2* metrics increased prediction of executive function (R²=0.455, p=0.008) and attention (R²=0.182, p=0.018) outcomes over clinical metrics alone. Specifically, R2* in the substantia nigra, caudate, STN, and hippocampus improved prediction of executive function, and in the putamen for attention. Interestingly, higher caudate R2* correlated with better executive function (p=0.043), whereas higher putamen R2* associated with worsening attention (p=0.018).

CONCLUSIONS:

Brain iron accumulation patterns, captured by susceptibility MRI, may add value to clinical evaluation in predicting neuropsychological outcomes post-DBS in PD. Further studies are warranted to validate these findings and understand the region-specific relationships between iron and DBS outcomes.

Neuropsychological outcomes after thalamic deep brain stimulation for essential tremor

INTRODUCTION

Non-motor DBS outcomes have received little attention in ET relative to PD. This study examines neuropsychological outcomes in ET following thalamic VIM DBS.

METHODS

Fifty patients completed neuropsychological evaluations preoperatively and approximately seven months postoperatively. Cognition and mood changes were analyzed at the group level and individual level. Additional associations with treatment, disease, and demographic characteristics were assessed.

RESULTS

Significant cognitive decline was not observed at the group level. At the individual level, 46% of patients demonstrated at least subtle overall cognitive decline (≥1SD on at least one test within at least two domains). Mild decline (≥1SD) was seen in 10%-29.17% of patients on individual tests across all cognitive domains, with highest rates in verbal memory. Substantial cognitive decline (≥2SD) occurred in less than 9% of the sample across all tests. Factors related to cognitive decline included higher DBS parameter settings, older age of ET onset, intracranial complications, and inability to reduce ET medications postoperatively. Depression and anxiety did not change when accounting for questionnaire items that could be falsely elevated by tremor.

CONCLUSION

Substantial cognitive decline after VIM DBS is rare in patients with ET. However, subtle decrements can occur across cognitive domains and particularly in verbal memory. DBS parameter settings may relate to cognitive decline. Further research is needed to better understand possible associations with electrode lateralization and other variables that could also relate to disease progression and test-retest effects. Symptoms of depression and anxiety remain stable.

Correlates of deep brain stimulation consensus conference decision to treat primary dystonia

BACKGROUND

Deep brain stimulation (DBS) is an effective treatment for motor disturbance in people with primary dystonia (PWD). Numerous factors are considered by an interdisciplinary consensus conference before deciding candidacy for DBS surgery (e.g., demographic, medical, cognitive, and behavioral factors). However, little is known about which of these factors are associated with PWD DBS surgery consensus conference decisions.

OBJECTIVE

Our goal was to examine whether pre-operative demographic, medical, and cognitive/behavioral variables are associated DBS consensus conference decisions in patients with dystonia.

METHODS

Thirty-two PWD completed comprehensive presurgery workup included neurological and neuropsychological exams, and neuroimaging in consideration for DBS surgery. An interdisciplinary conference committee either recommended or did not recommend DBS surgery based upon these data. Demographic and medical data (e.g., dystonia disease characteristics, medical comorbidities, medications) were also collected. We also examined impact from cardiovascular disease factors, using a Revised Cardiac Risk Index. PWD were grouped based on DBS conference decision (eligible: n = 21, ineligible: n = 11) and compared across demographic, medical, and cognitive/behavioral variables.

RESULTS

Across clinical variables, PWD who were deemed ineligible for DBS surgery had a higher Revised Cardiac Risk Index. PWD who were classified as ineligible displayed lower global cognitive functioning, working memory, phonemic fluency, memory retrieval, and cognitive flexibility.

CONCLUSIONS

Consensus decision making regarding DBS surgery eligibility involves a multifactorial process. We found that deficits in executive functioning were associated with the DBS consensus committee decision. We also observed elevated cardiac risk among these individuals, likely reflecting the relation between vascular health and cognition. Implications, and clinical and scientific applications of these findings are discussed.

Global Variability in Deep Brain Stimulation Practices for Parkinson's Disease

Introduction

Deep brain stimulation (DBS) has become a standard treatment option for select patients with Parkinson’s disease (PD). The selection process and surgical procedures employed have, to date, not been standardized.

Methods

A comprehensive 58-question web-based survey was developed with a focus on DBS referral practices and peri-operative management. The survey was distributed to the Parkinson’s Foundation Centers of Excellence, members of the International Parkinson’s Disease and Movement Disorders Society, and the Parkinson Study Group (Functional Neurosurgery Working Group) between December 2015 and May 2016.

Results

There were 207 individual respondents (20% response rate) drawn from 59 countries and 6 continents, of whom 64% received formal training in DBS. Thirteen percent of centers reported that DBS could proceed despite a confidence level of < 50% for PD diagnosis. A case-based approach to DBS candidacy was applied in 51.3% of centers without a cut-off for levodopa-responsiveness. Surprisingly, 33% of centers regularly used imaging for diagnostic confirmation of idiopathic PD. Thirty-one percent of centers reported that neuropsychological evaluation did not affect DBS target selection. Approximately half of the respondents reported determination of DBS candidacy based on a multidisciplinary committee evaluation and 1/3^rd reported that a committee was used for target selection. Eight percent of respondents felt that psychosocial factors should not impact DBS candidacy nor site selection. Involvement of allied health professionals in the preoperative process was sparse. There was high variability in preoperative education about DBS outcome expectations. Approximately half of the respondents did not utilize a “default brain target,” though STN was used more commonly than GPi. Specific DBS procedure techniques applied, as well as follow-up timelines, were highly variable.

Conclusion

Results revealed high variability on the best approaches for DBS candidate selection, brain target selection, procedure type, and postoperative practices. Cognitive and mood assessments were underutilized. There was low reliance on multidisciplinary teams or psychosocial factors to impact the decision-making process. There were small but significant differences in practice across global regions, especially regarding multidisciplinary teams. The wide variability of responses across multiple facets of DBS care highlights the need for prospective studies to inform evidence-based guidelines.

Factors Associated With Postoperative Confusion and Prolonged Hospital Stay Following Deep Brain Stimulation Surgery for Parkinson Disease

BACKGROUND

Several patient and disease characteristics are thought to influence DBS outcomes; however, most previous studies have focused on long-term outcomes with only a few addressing immediate postoperative course.

OBJECTIVE

To evaluate predictors of immediate outcomes (postoperative confusion and length of postoperative hospitalization) following deep brain stimulation surgery (DBS) in Parkinson disease (PD) patients.

METHODS

We conducted a retrospective study of PD patients who underwent DBS at our institution from 2006 to 2011. We computed the proportion of patients with postoperative confusion and those with postoperative hospitalization longer than 2 d. To look for associations, Fisher's exact tests were used for categorical predictors and logistic regression for continuous predictors.

RESULTS

We identified 130 patients [71% male, mean age: 63 ± 9.1, mean PD duration: 10.7 ± 5.1]. There were 7 cases of postoperative confusion and 19 of prolonged postoperative hospitalization. Of the 48 patients with tremors, none had postoperative confusion, whereas 10.1% of patients without tremors had confusion (P = .0425). Also, 10.2% of patients with preoperative falls/balance-dysfunction had postoperative confusion, whereas only 1.6% of patients without falls/balance-dysfunction had postoperative confusion (P = .0575). For every one-unit increase in score on the preoperative on-UPDRS III/MDS-UPDRS III score, the odds of having postoperative confusion increased by 10% (P = .0420). The following factors were noninfluential: age, disease duration, dyskinesia, gait freezing, preoperative levodopa-equivalent dose, number of intraoperative microelectrode passes, and laterality/side of surgery.

CONCLUSION

Absence of tremors and higher preoperative UPDRS III predicted postoperative confusion after DBS in PD patients. Clinicians' awareness of these predictors can guide their decision making regarding patient selection and surgical planning.

The UF Deep Brain Stimulation Cognitive Rating Scale (DBS-CRS): Clinical Decision Making, Validity, and Outcomes

To more efficiently communicate the results of neuropsychological assessment to interdisciplinary teams, the University of Florida Neuropsychology Service developed a Deep Brain Stimulation-Cognitive Rating Scale (DBS-CRS). This tool condensed results of a 3-h exam into a five-point scale ranging from 1 (least) to 5 (most) cognitive concern for DBS surgery. In this study, we evaluated the role of the DBS-CRS in clinical decisions by the interdisciplinary team to proceed to surgery, its relationship to objective neuropsychological scores, and its predictive utility for clinical outcome. We retrospectively examined 189 patients with Parkinson's disease who were evaluated for DBS candidacy (mean age 64.8 [SD 9.2], disease duration 8.9 years [SD 5.0], UPDRS-Part III off medication 38.5 [SD 10.5], Dementia Rating Scale-II 135.4 [SD 6.0]). Approximately 19% of patients did not proceed to surgery, with neuropsychological red flags being the most commonly documented reason (57%). Patients who underwent DBS surgery had significantly better DBS-CRS scores than those who did not (p < 0.001). The two strongest and unique neuropsychological contributors to DBS-CRS ratings were delayed memory and executive function, followed by language and visuoperception, based on hierarchical linear regression that accounted for 77.2% of the variance. In terms of outcome, DBS-CRS scores were associated with higher quality of life, less severe motor symptoms, and better daily functioning 6 months following DBS surgery. Together, these findings support the construct and predictive validity of the DBS-CRS as a concise tool for effectively communicating pre-DBS cognitive concerns to an interdisciplinary team, thereby aiding decision making in potential DBS candidates.

Contact Location and Neuropsychological Outcomes in Subthalamic Deep Brain Stimulation

BACKGROUND

A host of influences contribute to cognitive and behavioral changes following deep brain stimulation. The location of the active cathode is likely an important variable but it has received little attention.

OBJECTIVE

To determine whether active contact location relative to the subthalamic nucleus and other neighboring structures is related to nonmotor outcomes.

METHODS

We identified a retrospective, cross-sectional sample of 46 patients who underwent subthalamic nucleus deep brain stimulation for treatment of idiopathic Parkinson's disease. T-tests or nonparametric equivalents were used to detect baseline differences between unilateral left, unilateral right, and bilateral surgical groups. Correlation and partial correlational analyses identified relationships between contact location variables and alterations in cognitive, mood, quality of life, motor, and disease variables.

RESULTS

Medial contact locations within the left subthalamic nucleus were correlated with improvements in self-reported mood (r12 = -0.78, P = .001; 95% confidence interval [CI] = -0.43 to -0.93) but worsening semantic fluency (r26 = -0.38, P = .048; 95% CI = -0.01 to -0.66). Phonemic fluency worsened with more posterior left placement (r34 = 0.35, P = .036; 95% CI = 0.03 to 0.61). Memory outcome was related to right hemisphere stimulation voltage (r29 = -0.40, P = .022; 95% CI = -0.05 to -0.66), which is likely a proxy for variable electrode location.

CONCLUSION

Location of the active contact is related to nonmotor outcomes, even in electrodes that are adequately placed. This is relevant to clinical care as there appears to be a trade-off between mood and fluency abilities that should be considered during surgical planning according to preoperative patient characteristics.

Patients' shifting goals for deep brain stimulation and informed consent

OBJECTIVE

To determine using a repeated-measures, prospective design whether deep brain stimulation (DBS) results in changes in the importance of symptom and behavioral goals individually identified by patients with Parkinson disease (PD) before DBS surgery.

METHODS

Fifty-two participants recruited from a consecutive series completed a semistructured interview soliciting their rank-ordered symptom and behavioral goals and corresponding visual analog scales measuring perceived symptom severity and limits to goal attainment. Rank orders were reassessed at 2 times after DBS. Changes in rank order over time were examined with χ² analyses. The relationships between change in symptom severity/limits to behavioral goal attainment and change in rank order were examined with mixed-effects linear regression models.

RESULTS

Most participants changed the rank order of their symptom (81%) and behavioral (77%) goals 3 months after DBS surgery. Change in rank order of symptom goals was significantly related to change in severity ratings such that improvements in self-reported symptom severity were associated with reductions in rank. In contrast, no such relationship was evident for the behavioral goals.

CONCLUSION

These data illustrate how patients' primary goals for DBS shift early in stimulation and highlight the important differences between symptom and behavioral goals. Changes in the rank order of symptom goals were related to changes in symptom severity, whereas subtler shifts in behavioral goals were unrelated to improvements after DBS. This observation suggests that DBS does not affect goals that may be more reflective of core personal values. The findings provide empiric data that can help improve the informed consent process.

Some Clinically Useful Information that Neuropsychology Provides Patients, Carepartners, Neurologists, and Neurosurgeons About Deep Brain Stimulation for Parkinson's Disease

Deep brain stimulation (DBS) is an effective (but non-curative) treatment for some of the motor symptoms and treatment complications associated with dopaminergic agents in Parkinson's disease (PD). DBS can be done relatively safely and is associated with quality of life gains. In most DBS centers, neuropsychological evaluations are performed routinely before surgery, and sometimes after surgery. The purpose of such evaluation is not to decide solely on its results whether or not to offer DBS to a given candidate, but to provide the patient and treatment team with the best available information to make reasonable risk-benefit assessments. This review provides information relevant to the questions often asked by patients and their carepartners, neurologists, and neurosurgeons about neuropsychological outcomes of DBS, including neuropsychological adverse event rates, magnitude of cognitive changes, outcomes after unilateral versus bilateral surgery directed at various targets, impact of mild cognitive impairment (MCI) on outcome, factors implicated in neurobehavioral outcomes, and safety of newer interventions or techniques such as asleep surgery and current steering.

The Role of a Neuropsychologist on a Movement Disorders Deep Brain Stimulation Team

The term movement disorders is misleading in the implication that the symptoms are limited to motor problems. Most movement disorders include a variety of neurobehavioral and neurocognitive symptoms that require neuropsychological expertise. The goal of this paper is to provide a rationale and practical roadmap for neuropsychologists' involvement in a Movement Disorders team with a specific focus on pre-operative deep brain stimulation (DBS) evaluations. Pragmatic recommendations regarding requisite skills, clinical practice, recommendations, communication, and benefits are outlined.

Role of clinical neuropsychology in deep brain stimulation: Review of the literature and considerations for clinicians

Deep Brain Stimulation (DBS) is an effective surgical therapy for several neurological movement disorders. The clinical neuropsychologist has a well-established role in the neuropsychological evaluation and selection of surgical candidates. In this article, we argue that the clinical neuropsychologist's role is much broader, when considered in relation to applied psychologists' core competencies. We consider the role of the clinical neuropsychologist in DBS in relation to: assessment, formulation, evaluation and research, intervention or implementation, and communication. For each competence the relevant evidence-base was reviewed. Clinical neuropsychology has a vital role in presurgical assessment of cognitive functioning and psychological, and emotional and behavioral difficulties. Formulation is central to the selection of surgical candidates and crucial to intervention planning. Clinical neuropsychology has a well-established role in postsurgical assessment of cognitive functioning and psychological, emotional, and behavioral outcomes, which is fundamental to evaluation on an individual and service level. The unique contribution clinical neuropsychology makes to pre- and postsurgical interventions is also highlighted. Finally, we discuss how clinical neuropsychology can promote clear and effective communication with patients and between professionals.

Cognitive Impact of Deep Brain Stimulation on Parkinson's Disease Patients

Subthalamic nucleus (STN) or globus pallidus interna (GPi) deep brain stimulation (DBS) is considered a robust therapeutic tool in the treatment of Parkinson's disease (PD) patients, although it has been reported to potentially cause cognitive decline in some cases. We here provide an in-depth and critical review of the current literature regarding cognition after DBS in PD, summarizing the available data on the impact of STN and GPi DBS as monotherapies and also comparative data across these two therapies on 7 cognitive domains. We provide evidence that, in appropriately screened PD patients, worsening of one or more cognitive functions is rare and subtle after DBS, without negative impact on quality of life, and that there is very little data supporting that STN DBS has a worse cognitive outcome than GPi DBS.

Are non-demented patients with Parkinson's disease able to decide about their own treatment?

INTRODUCTION

Patients with Parkinson's disease (PD) are often confronted with difficult medical decisions, which might be hampered by cognitive impairment or chronic stress. Little is known, however, about the capacity to make medical decisions and the influence of cognition and stress on this ability. This study determined whether non-demented Parkinson's disease patients are able to make medical decisions and whether this capacity is influenced by cognition and stress.

METHODS

Forty-six Parkinson's disease patients and 94 healthy controls were assessed with the MacArthur Competence Assessment Tool for Treatment during which participants were presented with deep brain stimulation as a treatment option for a fictional Parkinson's disease patient. Furthermore, all participants were examined with a stress questionnaire and a neuropsychological test battery.

RESULTS

Parkinson's disease patients performed better on the total scale and 'Understanding' subscale of the MacArthur Competence Assessment Tool for Treatment than healthy controls. Lower performance on the Concept Shifting Test in the Parkinson's disease group and lower performance on Letter Digit Substitution Test in the healthy control group predicted lower medical decision-making capacity. No association was found between stress and medical decision-making.

CONCLUSION

Non-demented Parkinson's disease patients show no impairments in medical decision-making compared to healthy controls. In fact, Parkinson's disease patients have a better understanding of their disease and the benefits and risks of treatment options than healthy controls. Psychomotor speed and attention were negatively associated with medical decision-making in both groups. This implies that when these cognitive functions decline, the capacity to make medical decisions also declines.

Insights gleaned by measuring patients' stated goals for DBS: More than tremor

OBJECTIVE

To report prospective repeated measures data detailing the perceived benefit of deep brain stimulation (DBS) on the most commonly cited symptom and activity goals identified by patients with Parkinson disease.

METHODS

Fifty-two participants were recruited from a consecutive series. Participants completed a semi-structured interview soliciting their symptom and behavioral goals and corresponding visual analog scales measuring perceived symptom severity and limits to goal attainment. Severity ratings were completed prior to and at 2 times following DBS. Changes in severity over time were assessed using a mixed effects linear model. The pattern of relationships between the severity ratings and standard clinical research (SCR) measures routinely administered were examined using Pearson correlations.

RESULTS

The most common symptom goals were improvements in tremor, gait, and nonmotor symptoms, whereas the most frequent behavioral goals related to interpersonal relationships, work, and avocational pursuits. Most severity ratings were significantly correlated with each other but not with the SCR measures. Significant improvements were evident on all SCR measures after DBS. Participants' severity ratings for their symptom and behavioral goals improved significantly over time although not all severity ratings changed in the same manner.

CONCLUSIONS

These data illustrate that improvements in participants' individually defined goals were evident over time and that some of these improvements occurred in areas in which the benefits associated with DBS are not as well-documented. The participants' severity ratings were not redundant with SCR measures, suggesting that novel and potentially important information can be gleaned by systematically assessing patients' goals.

Global cognitive scores do not predict outcome after subthalamic nucleus deep brain stimulation

BACKGROUND

Presence of dementia is a contraindication for DBS treatment of Parkinson's disease. Recent evidence suggests that borderline cognitive function, as measured with a common screening measure, the Mattis Dementia Rating Scale, has a negative impact on quality of life (QoL) after DBS of the STN.

METHODS

We attempted to replicate and extend this finding in a larger group of patients with a wider range of preoperative global cognitive performance.

RESULTS

Our data indicate that performance on the screening measure is not associated with QoL or medical outcomes, even with scores well below the cutoff for identifying dementia.

CONCLUSIONS

This cognitive screening measure lacks sufficient sensitivity to warrant its use in predicting which patients will show QoL benefit from DBS.