Deep brain stimulation and the role of the neuropsychologist

Cognitive subtypes in individuals with essential tremor seeking deep brain stimulation

Objective: Essential tremor (ET) is a common neurological disorder that has been associated with 60% increased risk of developing dementia. The goals of the present study were to: (a) learn whether individuals with advanced ET symptoms seeking deep brain stimulation (DBS) surgery would fall into distinct cognitive subgroups, and (b) learn how empirically derived subgroups map onto criteria for mild cognitive impairment (MCI). Method: Patients with ET (N = 201; mean age = 68.9 ± 8.9 years) undergoing pre-surgical evaluation for DBS completed a multi-domain neurocognitive assessment consisting of memory, executive function, visuospatial skill, language, and processing speed. Two cluster analytic approaches (K-means, hierarchical) were independently conducted to classify cognitive patterns using domain composites. Demographics, clinical characteristics, and proportion of cases meeting neuropsychologically defined criteria for MCI were examined among clusters. Results: A three-cluster solution reflected a Low Executive group (N = 64), Low Memory Multi-Domain group (N = 41), and Cognitively Normal group (N = 96). The Cognitively Normal group was older and more educated, with a higher Dementia Rating Scale-2 score. In total, 27.4% of participants met criteria for MCI. Of the MCI cases, most were in the Low Executive (41.8%) or Low Memory Multi-Domain groups (49.1%). In the latter, 65.9% of its members were classified as MCI versus 35.9% in the Low Executive group. Conclusions: Our study identified three cognitive subtypes of ET patients presenting for DBS. Future work should examine the subgroups for progression to dementia, particularly the Low Memory Multi-Domain subgroup which may be at highest risk.

International Regulatory Standards for the Qualitative Measurement of Deep Brain Stimulation in Clinical Research

Deep brain stimulation (DBS) has progressed to become a promising treatment modality for neurologic and psychiatric disorders like epilepsy and major depressive disorder due to its growing personalization. Despite evidence pointing to the benefits of DBS if tested on these personalized qualitative metrics, rather than randomized-control trial quantitative standards, the evaluation of these novel devices appears to be based on the latter. This study surveyed the presence of this trend in the national regulatory guidelines of the prominent DBS researching countries. It was found that two governing bodies, in the European Union and Australia, acknowledged the option for qualitative measures. These findings support further development of national regulatory guidelines, so the neuroscientific community developing these neurotechnologies can better understand the impact their treatments have on patients.

Methodological Considerations for Setting Up Deep Brain Stimulation Studies for New Indications

Deep brain stimulation (DBS) is a neurosurgical treatment with a growing range of indications. The number of clinical studies is expanding because of DBS for new indications and efforts to improve DBS for existing indications. To date, various methods have been used to perform DBS studies. Designing a clinical intervention study with active implantable medical devices has specific challenges while expanding patient treatment. This paper provides an overview of the key aspects that are essential for setting up a DBS study.

"Benign" tremor? A serial case report of 2.5 year progression from mild cognitive impairment to amnestic dementia following deep brain stimulator placement for essential tremor

Essential tremor (ET) is a prevalent neurological disorder with associated neuropsychological sequalae. Although cognitive deficits associated with ET are traditionally conceptualized as attention, processing speed, and executive impairments attributed to underlying frontal-subcortical dysfunction, emerging literature highlights the elevated frequency of progressive amnestic memory impairments in patients with ET. This case study centers around a 75-year-old woman with a 15-year history of ET who underwent deep brain stimulation (DBS) as well as three neuropsychological evaluations, one pre-surgically and two post-surgically at one and two-years post successful DBS surgery. Neuropsychological evaluation results revealed circumscribed mild and variable memory deficits pre-surgically and one-year post-surgically, However, two-years post-DBS, reliable change indices revealed significant declines in verbal/visual memory, consistent with an amnestic presentation, in addition to executive functions, aspects of higher-level language abilities, and overall IQ. This case study adds to a growing literature identifying a subset of ET patients with a neurodegenerative cognitive trajectory characterized by progressive, amnestic memory impairment. The case also highlights the importance of serial monitoring of cognition beyond the pre-surgical DBS workup to monitor for clinically significant decline(s).

A Review of Cognitive Outcomes Across Movement Disorder Patients Undergoing Deep Brain Stimulation

Introduction: Although the benefit in motor symptoms for well-selected patients with deep brain stimulation (DBS) has been established, cognitive declines associated with DBS can produce suboptimal clinical responses. Small decrements in cognition can lead to profound effects on quality of life. The growth of indications, the expansion of surgical targets, the increasing complexity of devices, and recent changes in stimulation paradigms have all collectively drawn attention to the need for re-evaluation of DBS related cognitive outcomes.

Methods: To address the impact of cognitive changes following DBS, we performed a literature review using PubMed. We searched for articles focused on DBS and cognition. We extracted information about the disease, target, number of patients, assessment of time points, cognitive battery, and clinical outcomes. Diseases included were dystonia, Tourette syndrome (TS), essential tremor (ET), and Parkinson's disease (PD).

Results: DBS was associated with mild cognitive issues even when rigorous patient selection was employed. Dystonia studies reported stable or improved cognitive scores, however one study using reliable change indices indicated decrements in sustained attention. Additionally, DBS outcomes were convoluted with changes in medication dose, alleviation of motor symptoms, and learning effects. In the largest, prospective TS study, an improvement in attentional skills was noted, whereas smaller studies reported variable declines across several cognitive domains. Although, most studies reported stable cognitive outcomes. ET studies largely demonstrated deficits in verbal fluency, which had variable responses depending on stimulation setting. Recently, studies have focused beyond the ventral intermediate nucleus, including the post-subthalamic area and zona incerta. For PD, the cognitive results were heterogeneous, although deficits in verbal fluency were consistent and related to the micro-lesion effect.

Conclusion: Post-DBS cognitive issues can impact both motor and quality of life outcomes. The underlying pathophysiology of cognitive changes post-DBS and the identification of pathways underpinning declines will require further investigation. Future studies should employ careful methodological designs. Patient specific analyses will be helpful to differentiate the effects of medications, DBS and the underlying disease state, including disease progression. Disease progression is often an underappreciated factor that is important to post-DBS cognitive issues.

Standardised Neuropsychological Assessment for the Selection of Patients Undergoing DBS for Parkinson's Disease

DBS is an increasingly offered advanced treatment for Parkinson's disease (PD). Neuropsychological assessment is considered to be an important part of the screening for selection of candidates for this treatment. However, no standardised screening procedure currently exists. In this study, we examined the use of our standardised neuropsychological assessment for the evaluation of surgical candidates and to identify risk factors for subsequent decline in cognition and mood. A total of 40 patients were assessed before and after DBS. Evaluation of mood and case notes review was also undertaken. Before DBS, patients with PD demonstrated frequent impairments in intellectual functioning, memory, attention, and executive function, as well as high rates of mood disorder. Post-DBS, there was a general decline in verbal fluency only, and in one patient, we documented an immediate and irreversible global cognitive decline, which was associated with older age and more encompassing cognitive deficits at baseline. Case note review revealed that a high proportion of patients developed mood disorder, which was associated with higher levels of depression at baseline and greater reduction in levodopa medication. We conclude that our neuropsychological assessment is suitable for the screening of candidates and can identify baseline risk factors, which requires careful consideration before and after surgery.

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.

Implantable Smart Technologies (IST): Defining the 'Sting' in Data and Device

In a world surrounded by smart objects from sensors to automated medical devices, the ubiquity of ‘smart’ seems matched only by its lack of clarity. In this article, we use our discussions with expert stakeholders working in areas of implantable medical devices such as cochlear implants, implantable cardiac defibrillators, deep brain stimulators and in vivo biosensors to interrogate the difference facets of smart in ‘implantable smart technologies’, considering also whether regulation needs to respond to the autonomy that such artefacts carry within them. We discover that when smart technology is deconstructed it is a slippery and multi-layered concept. A device’s ability to sense and transmit data and automate medicine can be associated with the ‘sting’ of autonomy being disassociated from human control as well as affecting individual, group, and social environments.

Deep Brain Stimulation Emergencies: How the New Technologies Could Modify the Current Scenario

After 25 years of deep brain stimulation (DBS) for the treatment of Parkinson's disease, it has become increasingly recognized that a range of postoperative urgent situations and emergencies may occur. In this review we describe the possible scenarios of DBS-related emergencies: perioperative (intraoperative and early postoperative) and postoperative settings and issues from suboptimal control of motor and nonmotor symptoms in the early programming phase and during long-term follow-up. We also outline potential advantages in the management of these emergencies offered by the newest devices, emerging technologies, and new possibilities in programming.

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.

The Times They Are a Changin': Neuropsychology and Integrated Care Teams

OBJECTIVE

To gather illustrative data from clinical neuropsychologists who are working in integrated care settings in order to provide an initial blueprint for moving forward in this new era of health care.

METHOD

A survey was designed to illustrate the ways in which neuropsychologists are participating in integrated care teams and distributed on major neuropsychology listservs. The survey evaluated the settings, roles, services provided, practice issues, remuneration, and impact of neuropsychologists' participation in integrated care teams with respect to patient care and health outcomes. Frequencies were used to summarize the findings as well as qualitative coding of narrative responses.

RESULTS

There were 412 respondents to the survey and 261 of those indicated that they worked in at least one integrated care setting. Neuropsychologists work in a variety of integrated care settings and provide diverse services which contribute to improved patient care and outcomes.

CONCLUSIONS

Three primary themes emerge from the findings with regard to the engagement and teams: advocacy, collaboration, and communication. We argue for the need for more easily accessible outcome studies illustrating the clinical benefits and cost-savings associated with inclusion of neuropsychologists in integrated care teams. In addition, educational and training initiatives are needed to better equip current and future clinical neuropsychologists to function effectively in integrated care settings.

Memory Similarities Between Essential Tremor and Parkinson's Disease: A Final Common Pathway?

OBJECTIVE

A growing body of literature supports the view that essential tremor (ET) involves alteration of cerebellar-thalamo-cortical networks which can result in working memory and executive deficits. In this study, we tested the hypothesis that individuals with ET would exhibit worse performance on memory tasks requiring more intrinsic organization and structuring (i.e., word lists) relative to those with fewer 'executive' demands (i.e., stories), similar to that previously observed in individuals with Parkinson's disease (PD).

METHOD

Participants included a convenience sample of 68 ET patients and 68 idiopathic PD patients, retrospectively matched based on age, education, and sex. All patients underwent routine neuropsychological evaluation assessing recent memory, auditory attention/working memory, language, and executive function. Memory measures included the Hopkins Verbal Learning Test-R and WMS-III Logical Memory.

RESULTS

Both ET and PD patients performed significantly worse on word list than story memory recall tasks. The magnitude of the difference between these two memory tasks was similar for ET and PD patients. In both patient groups, performance on measures of executive function and auditory attention/working memory was not distinctly correlated with word list vs. story recall.

CONCLUSIONS

These findings suggest that frontal-executive dysfunction in both ET and PD may negatively influence performance on memory tests that are not inherently organized. Although the pathophysiology of these two 'movement disorders' are quite distinct, both have downstream effects on thalamo-frontal circuitry which may provide a common pathway for a similar memory phenotype. Findings are discussed in terms of neuroimaging evidence, conceptual models, and best practice.

Cognitive effects of deep brain stimulation in patients with obsessive-compulsive disorder

BACKGROUND

Deep brain stimulation (DBS) is a promising treatment for treatment-refractory obsessive-compulsive disorder (OCD). However, the effects of DBS on cognitive functioning remain unclear. Therefore, we aimed to assess cognitive safety of DBS for treatment-refractory OCD and the association between clinical changes and cognitive functioning.

METHODS

Patients with treatment-refractory OCD treated with DBS targeted at the nucleus accumbens (NAcc) were compared with a control group of 14 patients with treatment-refractory OCD treated with care as usual. We assessed cognitive functioning at baseline, 3 weeks postoperatively and following 8 months of DBS. We compared change in clinical symptoms with cognitive changes.

RESULTS

There were 16 patients in the DBS group and 14 patients in the control group. Three weeks postoperatively, the DBS group showed a significantly reduced performance on measures of visual organization and verbal fluency and a trend toward reduced performance on measures of visual memory and abstract reasoning. Cognitive functioning was found to be stable on all other measures. After 8 months of DBS, reduced performances persisted, except for a significant improvement in verbal fluency. Cognitive functioning in all other domains remained unaffected. We found no correlation between improvement of clinical symptoms and cognitive changes.

LIMITATIONS

A limitation of this study was its relatively small sample size.

CONCLUSION

Deep brain stimulation targeted at the NAcc may be considered a safe method in terms of cognition because cognitive functioning was unaffected on most neuropsychological measures. Nevertheless, we observed some minor reduced performance on specific measures of executive functioning that were possibly associated with surgical intervention. Our results suggest that severity of OCD symptoms is independent of cognitive functioning.

The Core Assessment Program for Surgical Interventional Therapies in Parkinson's Disease (CAPSIT-PD): Tolerability of Preoperative Neuropsychological Testing for Deep Brain Stimulation in Parkinson's Disease

Objective

We examined tolerability of preoperative neuropsychological testing (the Core Assessment Program for Surgical Interventional Therapies in Parkinson's Disease [CAPSIT-PD] protocol) for DBS. We also examined factors that may influence tolerability, including fatigue, global cognitive function, depression, and patient-based characteristics.

Methods

In this retrospective study, we reviewed preoperative neuropsychological testing results from 35 patients who were scheduled to undergo DBS. We examined the overall tolerability of the full battery and the tolerability of each test. We placed attention on a test's placement in the fixed order of the battery to measure whether there was a clustering of poorly tolerated tests toward the end of the battery as an indication of fatigue. Spearman's rank correlation was used to determine the relationship between tolerability and (1) global cognitive function, (2) depression, and (3) patient-based characteristics.

Results

Fourteen subjects (40%) were able to tolerate the full battery and completed all 10 tests. The domains that were least tolerated pertained to executive function and procedural memory. There was a consistent time-based tolerability pattern that was observed. There was a significant correlation between tolerability and global cognitive function (ρ = 0.344; P = 0.043), but not depression (P = 0.197). There was a significant correlation between tolerability and age (ρ = -0.491; P = 0.003) and disease duration (ρ = -0.442; P = 0.008), but not UPDRS-III scores (P = 0.284).

Conclusion

Our results have shown limited tolerability of the full neuropsychological battery as outlined by the CAPSIT-PD protocol. We suggest the consideration of updating the neuropsychological assessment used in the CAPSIT-PD protocol.

The medial forebrain bundle as a deep brain stimulation target for treatment resistant depression: A review of published data

INTRODUCTION

Despite a wide variety of therapeutic interventions for major depressive disorder (MDD), treatment resistant depression (TRD) remains to be prevalent and troublesome in clinical practice. In recent years, deep brain stimulation (DBS) has emerged as an alternative for individuals suffering from TRD not responding to combining antidepressants, multiple adjunctive strategies and electroconvulsive therapy (ECT). Although the best site for TRD-DBS is still unclear, pilot data suggests that the medial forebrain bundle (MFB) might be a key target to accomplish therapeutic efficacy in TRD patients.

OBJECTIVE

To explore the anatomic, electrophysiologic, neurocognitive and treatment data supporting the MFB as a target for TRD-DBS.

RESULTS

The MFB connects multiple targets involved in motivated behavior, mood regulation and antidepressant response. Specific phenomenology associated with TRD can be linked specifically to the superolateral branch (sl) of the MFB (slMFB). TRD patients who received DBS-slMFB reported high response/remission rates with an improvement in functioning and no significant adverse outcomes in their physical health or neurocognitive performance.

DISCUSSION

The slMFB is an essential component of a network of structural and functional pathways connecting different areas possibly involved in the pathogenesis of mood disorders. Therefore, the slMFB should be considered as an exciting therapeutic target for DBS therapy to achieve a sustained relief in TRD patients.

CONCLUSION

There is an urgent need for clinical trials exploring DBS-slMFB in TRD. Further efforts should pursue measuring baseline pro-inflammatory cytokines, oxidative stress, and cognition as possible biomarkers of DBS-slMFB response in order to aid clinicians in better patient selection.

A case of an arachnoid cyst masquerading as corticobasal degeneration

We present an individual, "JD", a 69-year-old Caucasian, married female with symptoms that included progressive right arm stiffness, tremor, and clumsiness; increasing gait and balance disturbance; increased fatigue and emotionality. Neuropsychological evaluation revealed compromised semantics and language-associated functions; impaired visual constructional ability; markedly reduced cognitive and visuomotor processing speed; low average to average working memory; variable praxis performance; variable abstract reasoning, problem solving, and set shifting; and lower overall intellectual functioning compared to premorbid estimates. Overall, her neuropsychological profile indicated marked compromise of the frontal and left parietal regions. The data coupled with her symptom pattern and demographics partially fit corticobasal degeneration diagnostic criteria. Neuroimaging, however, performed 2 years prior to the assessment and again during the current workup revealed an enlarging arachnoid cyst compressing the left parietal and posterior frontal lobe and a small portion of the right medial frontal-parietal region. We discuss the neuroanatomical substrates involved in her cognitive presentation and how two very distinct pathological processes (corticobasal degeneration, arachnoid cyst) can result in two similar symptom presentations. We summarize how multidisciplinary assessment assists with differential diagnosis and treatment planning.

Long-term effects of nucleus accumbens deep brain stimulation in treatment-resistant depression: evidence for sustained efficacy

Deep brain stimulation (DBS) to the nucleus accumbens (NAcc-DBS) was associated with antidepressant, anxiolytic, and procognitive effects in a small sample of patients suffering from treatment-resistant depression (TRD), followed over 1 year. Results of long-term follow-up of up to 4 years of NAcc-DBS are described in a group of 11 patients. Clinical effects, quality of life (QoL), cognition, and safety are reported. Eleven patients were stimulated with DBS bilateral to the NAcc. Main outcome measures were clinical effect (Hamilton Depression Rating Scale, Montgomery-Asperg Rating Scale of Depression, and Hamilton Anxiety Scale) QoL (SF-36), cognition and safety at baseline, 12 months (n=11), 24 months (n=10), and last follow-up (maximum 4 years, n=5). Analyses were performed in an intent-to-treat method with last observation carried forward, thus 11 patients contributed to each point in time. In all, 5 of 11 patients (45%) were classified as responders after 12 months and remained sustained responders without worsening of symptoms until last follow-up after 4 years. Both ratings of depression and anxiety were significantly reduced in the sample as a whole from first month of NAcc-DBS on. All patients improved in QoL measures. One non-responder committed suicide. No severe adverse events related to parameter change were reported. First-time, preliminary long-term data on NAcc-DBS have demonstrated a stable antidepressant and anxiolytic effect and an amelioration of QoL in this small sample of patients suffering from TRD. None of the responders of first year relapsed during the observational period (up to 4 years).

Deep brain stimulation and cognitive decline in Parkinson's disease: a clinical review

Parkinson’s disease is a common and often debilitating disorder, with a growing prevalence accompanying global population aging. Current drug therapy is not satisfactory enough for many patients, especially after a few years of symptom progression. This is mainly due to the motor complications that frequently emerge as disease progresses. Deep brain stimulation (DBS) is a useful therapeutic option in carefully selected patients that significantly improves motor symptoms, functional status, and quality of life. However, cognitive impairment may limit patient selection for DBS, as patients need to have sufficient mental capabilities in order to understand the procedure, as well as its benefits and limitations, and cooperate with the medical team throughout the process of selection, surgery, and postsurgical follow-up. On the other hand it has been observed that certain aspects of cognitive performance may decline after DBS, namely when the therapeutic target is the widely used subthalamic nucleus. These are important pieces of information for patients, their families, and health care professionals. This manuscript reviews these aspects and their clinical implications.

Do stable patients with a premorbid depression history have a worse outcome after deep brain stimulation for Parkinson disease?

BACKGROUND

Deep brain stimulation (DBS) has been associated with mood sequelae in a subset of patients operated on in either the subthalamic nucleus or the globus pallidus internus for the treatment of Parkinson disease.

OBJECTIVE

To compare mood and motor outcomes in those with and without a presurgical history of depression.

METHODS

Unilateral subthalamic nucleus or unilateral globus pallidus internus DBS patients followed up for a minimum of 6 months were included. All patients underwent a comprehensive outpatient psychiatric evaluation by a board-certified psychiatrist. Psychiatric diagnoses were based on Diagnostic and Statistical Manual, fourth edition, text revision, nomenclature (American Psychiatric Association, 2000). Motor and mood outcomes were compared.

RESULTS

A total of 110 patients were included. There were no significant differences in baseline variables between the 2 groups. Those with a preoperative history of depression had significantly higher Beck Depression Inventory scores than the nondepression group after DBS (8.97 ± 7.55 vs 5.92 ± 5.71; P = .04). Patients with a depression history had less improvement (11.6%) in pre/post-DBS change when Unified Parkinson Disease Rating Scale motor scores were compared (P = .03) after adjustment for stimulation site and baseline demographic and clinical variables. Patients with a higher levodopa equivalent dose had a worse clinical motor outcome.

CONCLUSION

Patients with a preoperative depression history had higher Beck Depression Inventory scores after DBS and significantly less (albeit small) improvement in pre/post-DBS change in Unified Parkinson Disease Rating Scale motor scores than patients without a history of depression.

DBS candidates that fall short on a levodopa challenge test: alternative and important indications

INTRODUCTION

Candidacy for deep brain stimulation (DBS) in Parkinson disease (PD) is typically assessed by the preoperative motor response to levodopa along with an interdisciplinary evaluation. However, recent cases treated at our institution have achieved good outcomes with DBS despite a sub-30% improvement in motor scores. The aim of this study was to examine the outcomes of DBS in a subset of patients who failed to reach the 30% motor improvement threshold.

METHODS

A review of all DBS patients treated at the University of Florida Movement Disorders Center between 2002 and 2009 was performed utilizing a DBS database. All patients with sub-30% improvement in Unified Parkinson Disease Rating Scale Part III after dopaminergic medication administration were included.

RESULTS

Nine patients were identified; DBS was performed for severe dyskinesia (n=5), "on/off motor" fluctuations (n=1) and medication-refractory tremor (n=3). The target symptoms were improved in all patients. Postoperatively, scores on the Unified Parkinson Disease Rating Scale Part II and III and subscores on Parkinson disease questionnaire-39 improved (P<0.05).

CONCLUSIONS

Although motor response to levodopa remains the primary selection criteria for DBS candidacy in Parkinson disease, patients who do not meet the 30% threshold and have disabling symptoms may still benefit from DBS. Select patients with severe dyskinesia, "on/off" motor fluctuations, and/or medication-refractory tremor may experience significant benefits from DBS and should be considered on a case by case basis through an interdisciplinary team evaluation.

Neuropsychological safety of nucleus accumbens deep brain stimulation for major depression: effects of 12-month stimulation

OBJECTIVES

Deep brain stimulation (DBS) to the nucleus accumbens (NAcc-DBS) has antidepressant effects in patients suffering from treatment-resistant depression (TRD). However, limited information exists regarding the impact of NAcc-DBS on cognitive functioning. The aim of this study was to examine whether NAcc-DBS in patients with TRD has any cognitive effects.

METHODS

A comprehensive neuropsychological battery was administered to 10 patients with TRD before onset of bilateral NAcc-DBS and after 1 year of DBS stimulation. Neuropsychological testing covered the domains of attention, learning and memory, executive functions, visual perception, and language. Performance was analyzed at baseline and after 1 year of continuous DBS.

RESULTS

No evidence was found for cognitive decline following NAcc-DBS comparing test results after 1 year of NAcc-DBS with baseline. However, significantly improved cognitive performance on tests of attention, learning and memory, executive functions and visual perception was found. In addition, there was a general trend towards cognitive enhancement from below average to average performance. These procognitive effects were independent of the antidepressant effects of NAcc-DBS or changes in NAcc-DBS parameters.

CONCLUSIONS

These results not only support cognitive safety of NAcc-DBS but also stress its beneficial role in augmenting cognitive performance in patients with TRD.

The case for testing memory with both stories and word lists prior to dbs surgery for Parkinson's Disease

Patients seeking deep brain stimulation (DBS) surgery for Parkinson's disease (PD) typically undergo neuropsychological assessment to determine candidacy for surgery, with poor memory performance interpreted as a contraindication. Patients with PD may exhibit worse memory for word lists than for stories due to the lack of inherent organization in a list of unrelated words. Unfortunately, word list and story tasks are typically developed from different normative datasets, and the existence of a memory performance discrepancy in PD has been challenged. We compared recall of stories and word lists in 35 non-demented PD candidates for DBS. We administered commonly used neuropsychological measures of word list and story memory (Hopkins Verbal Learning Test, Logical Memory), along with a second word list task that was co-normed with the story task. Age-corrected scores were higher for the story task than for both word list tasks. Compared to story recall, word list recall correlated more consistently with motor severity and composite measures of processing speed, working memory, and executive functioning. These results support the classic view of fronto-subcortical contributions to memory in PD and suggest that executive deficits may influence word list recall more than story recall. We recommend a multi-componential memory battery in the neuropsychological assessment of DBS candidates to characterize both mesial temporal and frontal-executive memory processes. One should not rely solely on a word list task because patients exhibiting poor memory for word lists may perform better with stories and therefore deserve an interdisciplinary discussion for DBS surgery.

Pre- and post- GPi DBS neuropsychological profiles in a case of X-linked dystonia-Parkinsonism

We present the pre to post bilateral globus pallidus interna (GPi) deep brain stimulation neuropsychological profiles of a 69-year-old patient with a 12-year history of X-linked dystonia-Parkinsonism (XDP). Pre-operative cognitive function was impaired in almost all domains and this impaired performance was not dependent on his medications. Following DBS, changes in neuropsychological functioning were examined using Reliable Change Indices and standardized z-score comparisons. Results showed reductions in processing speed in the context of stable performance in language and visuospatial domains. Post-operative improvements occurred on a cognitive screening measure, verbal memory, and a test of problem-solving skills. This is the first report on an individual with XDP who was cognitively impaired, but had good outcome following GPi bilateral stimulation to treat debilitating motor symptoms. The possible mechanisms for his stable cognitive performance include the target of his DBS, reduced medication dosage, and improvement in dystonia that may in turn have reduced patient's pain.

Optogenetic neuronal control in schizophrenia

Schizophrenia is a serious mental disorder characterized by a heterogeneous spectrum of clinical manifestations. Schizophrenia is basically incurable. The discovery of antipsychotic medications in the late 1940s has helped control some of the symptoms but has not reversed the course of the disorder and has had limited effect on the debilitating symptoms of the illness. In recent years brain stimulation technologies have emerged in the bio-scientific scenery. Deep brain stimulation now plays an important role in the treatment of many neurological disorders, and seems promising in treating depression. Optogenetics is a new technology that offers control over neuronal activity by turning on and off distinct neuronal populations. It has a great advantage over previous brain stimulation technologies in that it is accurate and specific to the neurons intended for activation and control. There is no evidence that brain stimulation has been investigated in schizophrenia patients. This possibility was discussed in a single commentary that proposed the hippocampus and nucleus accumbence as targets for DBS in schizophrenia, however it was emphasized that the neurophysiology and neuroanatomy of schizophrenia have not been elucidated to the extent that brain stimulation can be planned. In light of new optogenetic technology time is ripe to seriously consider optional targets of intervention in the brain of schizophrenia patients. Any such target should involve neuronal circuits (1) known to be relevant for schizophrenia, (2) involved in cognitive and brain functions that are disturbed in schizophrenia, and (3) relevant to alleged neuronal network mechanisms that are presumably damaged or malfunctioning in schizophrenia. This paper reviews the relevant literature and proposes that optogenetic interventions in schizophrenia should begin in the prefrontal cortex and the Globus-Pallidus Subthalamic nuclei systems. In the protocol for the prefrontal cortex, wide-arbore and chandelier inhibitory interneurons should be targets for optogenetic intervention and in the Globus-Pallidus Subthalamic nuclei the fast spiking neurons should be targets for optogenetic intervention. These subsystems are critical modulators of neural complexity which is directly relevant to connectivity organization in the brain. Schizophrenia is described as a disturbance of connectivity organization in the brain treatable by the relevant optogenetic interventions promoted in this paper.

Lessons learned from a large single center cohort of patients referred for DBS management

BACKGROUND

Deep brain stimulation surgery (DBS) for movement disorders has become commonplace and patients are beginning to present to specialized centers for second opinions. We aimed to uncover reasons for referral by analyzing a large single center cohort of DBS patients referred for management.

METHODS

Data were collected prospectively on a cohort of one hundred and eight patients who presented to the UF Movement Disorders Center for management following implantation at outside DBS centers. Data collected included referral reasons, pre-operative evaluation, DBS programming thresholds, DBS placement, need for optimization of therapy, and ultimate patient outcomes.

RESULTS

Ninety percent of patients reported at least one area of symptomatic dissatisfaction with the results of their DBS. Common issues included pre-operative misdiagnosis (28%), presence or exacerbation of symptoms not addressable by current DBS technology (48%), lead misplacement (43%), and need for medication (27%) or DBS programming (37%) optimization. Compared with leads placed using microelectrode recording (MER), leads placed without MER were strongly associated with misplacement (p = 0.03). Overall, 42% of subjects had no improvement, 37% slight improvement and 21% large improvement after medical and/or surgical management.

CONCLUSIONS

This study reveals common reasons why DBS patients may seek follow-up care at another institution. Although 90% of patients reported one or more problematic areas, many of these could not be addressed by current DBS technology. Similar to prior studies, we found that lead misplacement was prominent, as was the need for optimization of medicines and/or stimulation.

Dystonia: a surgeon's perspective

Surgery for dystonia has a history stretching back for centuries including myotomy and other procedures on the musculoskeletal system. In the last century lesional procedures, mainly involving the pallidum became popular. More recently, with the advent of deep brain stimulation, bilateral medial pallidal stimulation has become commonplace. This review describes the issues with patient selection, technical aspects of implantation and effects as well as complications of the technique. Some of the rarer types of dystonia that have also been treated with DBS are also described.

Identification and management of deep brain stimulation intra- and postoperative urgencies and emergencies

Deep brain stimulation (DBS) has been increasingly utilized for the therapeutic treatment of movement disorders, and with the advent of this therapy more postoperative urgencies and emergencies have emerged. In this paper, we will review, identify, and suggest management strategies for both intra- and postoperative urgencies and emergencies. We have separated the scenarios into 1--surgery/procedure related, 2--hardware related, 3--stimulation-induced difficulties, and 4--others. We have included ten illustrative (and actual) case vignettes to augment the discussion of each issue.

Greater improvement in quality of life following unilateral deep brain stimulation surgery in the globus pallidus as compared to the subthalamic nucleus

While deep brain stimulation (DBS) surgery is a well-accepted treatment for Parkinson disease (PD) that improves overall quality of life (QoL), its effects across different domains of QoL are unclear. The study reported here directly compared the effects of unilateral DBS in subthalamic nucleus (STN) or globus pallidus (GPi) on QoL in 42 non-demented patients with medication-refractory PD. Patients were enrolled in the COMPARE trial, a randomized clinical trial of cognitive and mood effects of STN versus GPi DBS conducted at the University of Florida Movement Disorders Center. Patients underwent motor, mood, verbal fluency and QoL (Parkinson disease questionnaire: PDQ-39) measures before and 6 months following surgery. Groups experienced motor and mood improvements that did not differ by target. Patients with STN DBS evidenced a slight decrement on letter fluency. On average, all patients endorsed better overall QoL after surgery. However, despite similar motor and mood improvements, GPi patients improved more than STN patients (38 vs. 14%, respectively; P = 0.03). Patients reported better QoL on subscales of mobility, activities of daily living (ADLs), emotional well-being, stigma, cognition and discomfort, but not on those of social support and communication. Improvements on the mobility, ADLs, stigma and social support subscales were greater amongst GPi patients. In regression analyses, only depression changes independently predicted changes in overall QoL as well as emotional well-being and social support changes. Within the STN group only, declining category fluency scores correlated with poorer QoL on the communication subscale. Unilateral DBS in both STN and GPi improved QoL overall and in disparate domains 6 months after surgery. Patients receiving GPi DBS reported greater improvements that cannot be explained by differential mood or motor effects; however, verbal fluency changes may have partially contributed to lesser QoL improvements amongst STN patients.

Reoperation for suboptimal outcomes after deep brain stimulation surgery

OBJECTIVE

To examine a case series of reoperations for deep brain stimulation (DBS) leads in which clinical scenarios revealed suboptimal outcome from a previous operation. Suboptimally placed DBS leads are one potential reason for unsatisfactory results after surgery for Parkinson's disease (PD), essential tremor (ET), or dystonia. In a previous study of patients who experienced suboptimal results, 19 of 41 patients had misplaced leads. Similarly, another report commented that lead placement beyond a 2- to 3-mm window resulted in inadequate clinical benefit, and, in 1 patient, revision improved outcome. The goal of the current study was to perform an unblinded retrospective chart review of DBS patients with unsatisfactory outcomes who presented for reoperation.

METHODS

Patients who had DBS lead replacements after reoperation were assessed with the use of a retrospective review of an institutional review board-approved movement disorders database. Cases of reoperation for suboptimal clinical benefit were included, and cases of replacement of DBS leads caused by infection or hardware malfunction were excluded. Data points studied included age, disease duration, diagnosis, motor outcomes (the Unified Parkinson Disease Rating Scale III in PD, the Tremor Rating Scale in ET, and the Unified Dystonia Rating Scale in dystonia), quality of life (Parkinson's Disease Questionnaire-39 in PD), and the Clinician Global Impression scale. The data from before and after reoperation were examined to determine the estimated impact of repeat surgery.

RESULTS

There were 11 patients with PD, 7 with ET, and 4 with dystonia. The average age of the PD group was 52 years, the disease duration was 10 years, and the average vector distance of the location of the active DBS contact was adjusted 5.5 mm. Six patients (54%) with PD had preoperative off medication on DBS Unified Parkinson Disease Rating Scale scores that could be compared with postoperative off medication on DBS scores. The average improvement across this group of patients was 24.4%. The Parkinson's Disease Questionnaire-39 improved in the areas of mobility (28.18), activities of daily living (14.77), emotion (14.72), stigma (17.61), and discomfort (17.42). The average age of the ET group was 66 years, the disease duration was 29 years, and the average adjusted distance was 6.1 mm. Five ET patients (83.3%) in the cohort had a prereplacement on DBS Tremor Rating Scale and a postreplacement on DBS Tremor Rating Scale with the average improvement of 60.4%. The average age of the dystonia group was 39 years, the average disease duration was 7 years, and the average adjusted lead distance was 6.7 mm. Three patients (75%) with dystonia had prereplacement on DBS Unified Dystonia Rating Scale and postreplacement on DBS Unified Dystonia Rating Scale scores. Across these 3 dystonia patients, the improvement was 12.8%. Clinician Global Impression scale scores (1, very much improved; 2, much improved; 3, minimally improved; 4, no change; 5, minimally worse; 6, much worse; 7, very much worse) after replacement revealed the following results in patients with PD: 1, 7 patients; 2, 3 patients; 3, 1 patient); with ET (1, 4 patients; 2, 3 patients); and with dystonia (1, 1 patient; 2, 2 patients; 3, 1 patient). The latency from original lead placement to reoperation (repositioning/revision) overall was 28.9 months (range, 2-104 mo); however, in leads referred from outside institutions (n = 11 patients), this latency was 48 months (range, 12-104 mo) compared with leads implanted by surgeons from the University of Florida (n = 11 patients), which was 9.7 months (range, 2-19 mo). The most common clinical history was failure to achieve a perceived outcome; however, history of an asymmetric benefit was present in 4 (18.2%) of 22 patients, and lead migration was present in 3 (13.6%) of 22 patients.

CONCLUSION

There are many potential causes of suboptimal benefit after DBS. Timely identification of suboptimal lead placements followed by reoperation and repositioning/replacement in a subset of patients may improve outcomes.

Surgery for movement disorders

Movement disorders, such as Parkinson's disease, tremor, and dystonia, are among the most common neurological conditions and affect millions of patients. Although medications are the mainstay of therapy for movement disorders, neurosurgery has played an important role in their management for the past 50 years. Surgery is now a viable and safe option for patients with medically intractable Parkinson's disease, essential tremor, and dystonia. In this article, we provide a review of the history, neurocircuitry, indication, technical aspects, outcomes, complications, and emerging neurosurgical approaches for the treatment of movement disorders.

Neuropsychological impact of Cg25 deep brain stimulation for treatment-resistant depression: preliminary results over 12 months

The purpose of this study was to evaluate preservation of cognitive function after deep brain stimulation (DBS) of the subgenual cingulate (Cg25) for treatment-resistant depression (TRD). We have previously reported on the treatment methods, safety, and 6-month clinical outcome (Mayberg et al., Neuron. 2005;45:651-660). Comprehensive neuropsychological assessments tapping 4 domains of frontal lobe function, and general cognitive abilities, were completed before implantation and at 3, 6, and 12 months postonset of continuous DBS in 6 TRD patients. No adverse neuropsychological effects were noted following surgery, onset and maintenance of DBS with the exception of transient motor slowing noted at 3 and 6 months that improved to normative levels by 12 months. Several areas of cognition that were below average or impaired at baseline improved over follow-up, and these changes were not correlated with improvements in mood. Though the sample size is small, these results support cognitive safety of Cg25 DBS for TRD.