COVID-19 and Integrated Multidisciplinary Care Model in Parkinson's Disease: Literature Review & Future Perspectives

Clinical diversity and multi-systemic manifestations of Parkinson's disease (PD) necessitate the involvement of several healthcare professionals from different disciplines for optimal care. Clinical guidelines recommend that all persons with PD should have access to a broad range of medical and allied health professionals to implement an efficient and effective multidisciplinary care model. This is well supported by growing evidence showing the benefits of multidisciplinary interventions on improving quality of life and disease progression in PD. However, a "multidisciplinary" approach requires gathering healthcare professionals from different disciplines into an integrative platform for collaborative teamwork. With the Coronavirus Disease 2019 (COVID-19) pandemic, implementation of such a multidisciplinary care model has become increasingly challenging due to social distancing mandates, isolation and quarantine, clinics cancellation, among others. To address this problem, multidisciplinary teams are developing innovate virtual platforms to maintain care of people with PD. In the present review, we cover aspects on how SARS-CoV-2 has affected people with PD, their caregivers, and care team members. We also review current evidence on the importance of maintaining patient-centered care in the era of social distancing, and how can we utilize telehealth and innovative virtual platforms for multidisciplinary care in PD.

Closed-Loop Deep Brain Stimulation to Treat Medication-Refractory Freezing of Gait in Parkinson's Disease

Background: Treating medication-refractory freezing of gait (FoG) in Parkinson’s disease (PD) remains challenging despite several trials reporting improvements in motor symptoms using subthalamic nucleus or globus pallidus internus (GPi) deep brain stimulation (DBS). Pedunculopontine nucleus (PPN) region DBS has been used for medication-refractory FoG, with mixed findings. FoG, as a paroxysmal phenomenon, provides an ideal framework for the possibility of closed-loop DBS (CL-DBS).

Methods: In this clinical trial (NCT02318927), five subjects with medication-refractory FoG underwent bilateral GPi DBS implantation to address levodopa-responsive PD symptoms with open-loop stimulation. Additionally, PPN DBS leads were implanted for CL-DBS to treat FoG. The primary outcome of the study was a 40% improvement in medication-refractory FoG in 60% of subjects at 6 months when “on” PPN CL-DBS. Secondary outcomes included device feasibility to gauge the recruitment potential of this four-lead DBS approach for a potentially larger clinical trial. Safety was judged based on adverse events and explantation rate.

Findings: The feasibility of this approach was demonstrated as we recruited five subjects with both “on” and “off” medication freezing. The safety for this population of patients receiving four DBS leads was suboptimal and associated with a high explantation rate of 40%. The primary clinical outcome in three of the five subjects was achieved at 6 months. However, the group analysis of the primary clinical outcome did not reveal any benefit.

Interpretation: This study of a human PPN CL-DBS trial in medication-refractory FoG showed feasibility in recruitment, suboptimal safety, and a heterogeneous clinical effect in FoG outcomes.

Neurophysiological Correlates of Gait in the Human Basal Ganglia and the PPN Region in Parkinson's Disease

This study aimed to characterize the neurophysiological correlates of gait in the human pedunculopontine nucleus (PPN) region and the globus pallidus internus (GPi) in Parkinson's disease (PD) cohort. Though much is known about the PPN region through animal studies, there are limited physiological recordings from ambulatory humans. The PPN has recently garnered interest as a potential deep brain stimulation (DBS) target for improving gait and freezing of gait (FoG) in PD. We used bidirectional neurostimulators to record from the human PPN region and GPi in a small cohort of severely affected PD subjects with FoG despite optimized dopaminergic medications. Five subjects, with confirmed on-dopaminergic medication FoG, were implanted with bilateral GPi and bilateral PPN region DBS electrodes. Electrophysiological recordings were obtained during various gait tasks for 5 months postoperatively in both the off- and on-medication conditions (obtained during the no stimulation condition). The results revealed suppression of low beta power in the GPi and a 1-8 Hz modulation in the PPN region which correlated with human gait. The PPN feature correlated with walking speed. GPi beta desynchronization and PPN low-frequency synchronization were observed as subjects progressed from rest to ambulatory tasks. Our findings add to our understanding of the neurophysiology underpinning gait and will likely contribute to the development of novel therapies for abnormal gait in PD. Clinical Trial Registration: Clinicaltrials.gov identifier; NCT02318927.

Square Biphasic Pulse Deep Brain Stimulation for Parkinson's Disease: The BiP-PD Study

Background

Conventional Parkinson’s disease (PD) deep brain stimulation (DBS) utilizes a pulse with an active phase and a passive charge-balancing phase. A pulse-shaping strategy that eliminates the passive phase may be a promising approach to addressing movement disorders.

Objectives

The current study assessed the safety and tolerability of square biphasic pulse shaping (sqBIP) DBS for use in PD.

Methods

This small pilot safety and tolerability study compared sqBiP versus conventional DBS. Nine were enrolled. The safety and tolerability were assessed over a 3-h period on sqBiP. Friedman’s test compared blinded assessments at baseline, washout, and 30 min, 1 h, 2 h, and 3 h post sqBIP.

Results

Biphasic pulses were safe and well tolerated by all participants. SqBiP performed as well as conventional DBS without significant differences in motor scores nor accelerometer or gait measures.

Conclusion

Biphasic pulses were well-tolerated and provided similar benefit to conventional DBS. Further studies should address effectiveness of sqBIP in select PD patients.

Changes in Midline Tremor and Gait Following Deep Brain Stimulation for Essential Tremor

Background

Essential tremor (ET) is a common movement disorder characterized by kinetic and postural tremor in the upper extremities and frequently in the midline. Persons with ET often also exhibit gait ataxia. Previous studies have observed associations between midline tremor severity and gait ataxia in persons with ET, suggesting a common pathophysiology distinct from that of upper extremity tremor. However, a causal link between midline tremor and gait impairment has not been established.

Methods

We investigated tremor and gait in 24 persons with ET before and after implantation of unilateral deep brain stimulation into the ventralis intermedius nucleus of the thalamus.

Results

Stimulation significantly improved tremor in the targeted upper extremity and midline. However, gait was unaffected at the cohort level. Furthermore, improvement in midline tremor was not significantly associated with gait improvement.

Discussion

These findings revealed that midline tremor and gait impairment may be dissociable in persons with ET.

Efficacy and Safety of Deep Brain Stimulation in Tourette Syndrome: The International Tourette Syndrome Deep Brain Stimulation Public Database and Registry

Importance

Collective evidence has strongly suggested that deep brain stimulation (DBS) is a promising therapy for Tourette syndrome.

Objective

To assess the efficacy and safety of DBS in a multinational cohort of patients with Tourette syndrome.

Design, Setting, and Participants

The prospective International Deep Brain Stimulation Database and Registry included 185 patients with medically refractory Tourette syndrome who underwent DBS implantation from January 1, 2012, to December 31, 2016, at 31 institutions in 10 countries worldwide.

Exposures

Patients with medically refractory symptoms received DBS implantation in the centromedian thalamic region (93 of 163 [57.1%]), the anterior globus pallidus internus (41 of 163 [25.2%]), the posterior globus pallidus internus (25 of 163 [15.3%]), and the anterior limb of the internal capsule (4 of 163 [2.5%]).

Main Outcomes and Measures

Scores on the Yale Global Tic Severity Scale and adverse events.

Results

The International Deep Brain Stimulation Database and Registry enrolled 185 patients (of 171 with available data, 37 females and 134 males; mean [SD] age at surgery, 29.1 [10.8] years [range, 13-58 years]). Symptoms of obsessive-compulsive disorder were present in 97 of 151 patients (64.2%) and 32 of 148 (21.6%) had a history of self-injurious behavior. The mean (SD) total Yale Global Tic Severity Scale score improved from 75.01 (18.36) at baseline to 41.19 (20.00) at 1 year after DBS implantation (P < .001). The mean (SD) motor tic subscore improved from 21.00 (3.72) at baseline to 12.91 (5.78) after 1 year (P < .001), and the mean (SD) phonic tic subscore improved from 16.82 (6.56) at baseline to 9.63 (6.99) at 1 year (P < .001). The overall adverse event rate was 35.4% (56 of 158 patients), with intracranial hemorrhage occurring in 2 patients (1.3%), infection in 4 patients with 5 events (3.2%), and lead explantation in 1 patient (0.6%). The most common stimulation-induced adverse effects were dysarthria (10 [6.3%]) and paresthesia (13 [8.2%]).

Conclusions and Relevance

Deep brain stimulation was associated with symptomatic improvement in patients with Tourette syndrome but also with important adverse events. A publicly available website on outcomes of DBS in patients with Tourette syndrome has been provided.

Causes and outcomes of hospitalization in Lewy body dementia: A retrospective cohort study

INTRODUCTION

Understanding hospitalization in Lewy body dementia (LBD) is a known knowledge gap. We aimed to identify common causes, medication profiles, complications, and outcomes of hospitalization in LBD.

METHODS

A retrospective cohort study investigated details of academic medical center hospitalizations over a two-year period for patients with LBD. Data collected included demographics, home medications, pre-hospital living status, reason for admission, admission service, inpatient medications, complications, and discharge status. Non-parametric statistics assessed associations between variables and length of stay. Odds of a change in living situation based on admission variables was calculated.

RESULTS

The study included 178 hospitalizations (117 individuals). Neuropsychiatric symptoms were the most common admission reason (40%), followed by falls (24%) and infection (23%). Patients were usually admitted to medicine services; neurology or psychiatric consultations occurred less than 40% of the time. Antipsychotics were administered during 38% of hospitalizations. Use of antipsychotics other than quetiapine or clozapine was associated with longer length of stay and increased odds of discharge to a higher level of care. One-third of hospitalizations resulted in transition to a higher level of care; 15% ended in hospice care or death.

CONCLUSION

The most common reasons for hospitalization in LBD are potentially modifiable. Opportunities for improved care include increased involvement of neurological and psychiatric services, delirium prevention strategies, and reduced antipsychotic use. Clinicians should counsel patients and families that hospitalizations in LBD can be associated with end of life. Research is needed to identify strategies to prevent hospitalization and optimal standards for inpatient care.

FUNDING

Lewy body dementia research at the University of Florida is supported by the University of Florida Dorothy Mangurian Headquarters for Lewy Body Dementia and the Raymond E. Kassar Research Fund for Lewy Body Dementia.

A randomized study of botulinum toxin versus botulinum toxin plus physical therapy for treatment of cervical dystonia

BACKGROUND

Physical therapy (PT) for cervical dystonia is not well studied, and the underlying physiological effects are not known.

METHODS

We enrolled 26 subjects comprising of 16 cervical dystonia and 10 healthy controls for normative physiological data. We randomized cervical dystonia patients who reported suboptimal benefits on botulinum toxin (BoNT) injections to BoNT alone (BoNT arm) or BoNT plus PT (PT-BoNT arm). PT-BoNT arm received manual PT on the injection day followed by six weeks of home-exercise program. Home-exercise program comprised of stretching, range-of-motion and isometric exercises. The primary outcome was change from baseline in Toronto Western spasmodic torticollis rating scale (TWSTRS) that was recorded six weeks after exercise program. TWSTRS was video evaluated by blinded raters. We probed sensorimotor plasticity with transcranial magnetic stimulation (TMS) using a paired associative stimulation (PAS) paradigm.

RESULTS

TWSTRS score improved (severity 31%, p = 0.002; pain 28%, p = 0.01) and PAS plasticity decreased (p = 0.01) in PT-BoNT arm compared to BoNT arm. PAS values for PT-BoNT arm were found to approach values of healthy control values. Change in PAS measure correlated significantly with TWSTRS change (severity, r = 0.56, p = 0.04; pain, r = 0.61, p = 0.03. TWSTRS disability score only approached significance (p = 0.14) when comparing the two treatment arms.

CONCLUSION

PT is a potential adjunct in patients with cervical dystonia who report suboptimal benefits with BoNT therapy. PT related benefits in cervical dystonia are likely mediated through modulation of sensorimotor plasticity.

Longitudinal Follow-up of Impedance Drift in Deep Brain Stimulation Cases

Background

Impedance is an integral property of neuromodulation devices that determines the current delivered to brain tissue. Long-term variability in therapeutic impedance following deep brain stimulation (DBS) has not been extensively investigated across different brain targets. The aim was to evaluate DBS impedance drift and variability over an extended postoperative period across common DBS targets.

Methods

Retrospective data from 1,764 electrode leads were included and drawn from 866 DBS patients enrolled in the University of Florida Institutional Review Board-approved INFORM database and analyzed up to 84 months post implantation. An exploratory analysis was conducted to identify trends in impedances using a Mann–Kendall test of trend.

Results

There were 866 patients and 1,764 leads available for analysis. The majority of subjects had Parkinson’s disease (60.7%). The mean age at implantation was 58.7 years old and the mean follow-up time was 36.8 months. There were significant fluctuations in the mean impedance of all electrodes analyzed that largely stabilized by 6 months except for the subthalamic nucleus (STN) target, in which fluctuations persisted throughout the duration of follow-up with a continued downward trend (p < 0.001).

Discussion

The drift in impedance observed primarily within the first 6 months is in keeping with prior studies and is likely due to surgical micro-lesioning effects and brain parenchyma remodeling at the electrode–tissue interface, typically at values approximating 1,000 Ω. The differences in impedance trends over time in the various DBS targets may be due to underlying differences in structure and tissue composition.

Impulse control disorders in Parkinson's: Sleep disorders and nondopaminergic associations

OBJECTIVES

Impulse control disorders (ICDs) are common among patients with Parkinson's disease (PD). Risk factors identified for developing ICDs include young age, family history, and impulsive personality traits. However, the association of these potentially disabling disorders with nondopaminergic drugs and sleep disorders has been understudied. Our objective was to examine the association between ICDs and nondopaminergic medications and sleep disorders.

METHODS

We conducted an observational study of 53 patients with PD from the National Institute of Neurology and Neurosurgery. ICDs were diagnosed using the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease Rating Scale (QUIP-RS). Patients underwent polysomnography screening to diagnose the presence of sleep disorders. We documented the presence of dopaminergic and nondopaminergic medications, including monoamine oxidase type B inhibitors (MAOBIs), antidepressants, sleep inductors, and antipsychotics.

RESULTS

ICDs were reported in 18.9% of the patients (n = 10), and sleep disorders were diagnosed in 81.1% of patients (n = 43). 32.1% of the patients were on antidepressants, 17% on MAOBIs, 15.1% on sleep inductors, and 1.9% on antipsychotics. We observed that QUIP-RS A-D subscore depended on the presence of antidepressants (p = .03) and sleep inductors (p = .02). Sleep disorders were not associated with the total QUIP-RS score (p = .93) or QUIP-RS A-D subscore (p = .81).

CONCLUSION

Antidepressants and sleep inductors were significant predictors for individual QUIP-RS items and subscores. Our results suggest that nondopaminergic drugs commonly used for PD may be associated with impulse control disorders. We did not identify a relationship between ICDs and polysomnography-confirmed sleep disorders in patients with PD. Larger and longitudinal studies are needed to confirm our results.

Potential indications for deep brain stimulation in neurological disorders: an evolving field

Deep brain stimulation (DBS) is an established therapy for appropriately selected patients with movement disorders and neuropsychiatric conditions. Although the exact mechanisms and biology of DBS are not fully understood, it is a safe and well-tolerated therapy for many refractory cases of neuropsychiatric disease. Increasingly, DBS has been explored in other conditions with encouraging results. In this paper, available data is reviewed and new DBS targets, challenges and future directions in neurological disorders are explored. A detailed search of the medical literature discussing the potential use of DBS for neurological disorders excluding accepted indications was conducted. All reports were analyzed individually for content and redundant articles were excluded by examining individual abstracts. The level of evidence for each indication was summarized. Multiple studies report promising preliminary data regarding the safety and efficacy of DBS for a variety of neurological indications including chronic pain, tinnitus, epilepsy, Tourette syndrome, Huntington's disease, tardive dyskinesia and Alzheimer's disease. The initial results of DBS studies for diverse neurological disorders are encouraging but larger, controlled, prospective, homogeneous clinical trials are necessary to establish long-term safety and effectiveness. The field of neuromodulation continues to evolve and advances in DBS technology, stereotactic techniques, neuroimaging and DBS programming capabilities are shaping the present and future of DBS research and use in practice.

Inpatient morbidity after spinal deformity surgery in patients with movement disorders

Background

To investigate the inpatient perioperative morbidity rate of patients with movement disorders (MD) after spinal deformity surgery.

Methods

The Nationwide Inpatient Sample database from 2002 to 2011 was queried to identify adult patients with MD who underwent spinal deformity surgery. Complication rates were compared between patients with MD and controls. A multiple logistic regression analysis was conducted to assess the effect of MD on outcome.

Results

A total of 365 patients with MD (3.3%) were identified among 11,043 patients undergoing surgery for spinal deformity. Patients with MD were on average 8 years older than the control group (67 vs. 59 years of age, P<0.001). The complication rate was 55.1% for patients with MD and 43.7% for patients without MD (P<0.001). The most common complication was acute post-hemorrhagic anemia, which occurred in 31.9% of all patients (41.6% in MD patients and 31.5% in the control group, P<0.001). Other complications that were more common in patients with MD included delirium (P<0.001), acute kidney injury (P=0.032), and pulmonary embolism (P=0.014). After controlling for patient age, sex, osteoporosis, complex procedures, fusion to the lumbosacral spine, use of bone morphogenetic protein, and use of blood transfusion, patients with MD were 1.3 times more likely to develop a complication compared to patients without MD [odds ratio (OR), 1.27; 95% confidence interval (CI), 1.02-1.59; P=0.032] on multiple logistic regression analysis. No significant difference in hospital stay was observed.

Conclusions

Patients with MD who undergo spinal deformity surgery may be at risk of higher rate of complications compared to patients without these disorders.

Ventral Intermediate Nucleus Versus Zona Incerta Region Deep Brain Stimulation in Essential Tremor

Background

The ventral intermediate nucleus (VIM) is the target of choice for Essential Tremor (ET) deep brain stimulation (DBS). Renewed interest in caudal zona incerta (cZI) stimulation for tremor control has recently emerged and some groups believe this approach may address long-term reduction of benefit seen with VIM-DBS.

Objectives

To compare clinical outcomes and DBS programming in the long-term between VIM and cZI neurostimulation in ET-DBS patients.

Materials and Methods

A retrospective review of 53 DBS leads from 47 patients was performed. Patients were classified into VIM or cZI groups according to the location of the activated DBS contact. Demographics, DBS settings, and Tremor Rating Scale scores were compared between groups at baseline and yearly follow-up to 4 years after DBS. Student t-tests and analysis of variance (ANOVA) were used to compare variables between groups.

Results

Relative to baseline, an improvement in ON-DBS tremor scores was observed in both groups from 6 months to 4 years post-DBS (p < 0.05). Although improvement was still significant at 4 years, scores from month 6 to 2 years were comparable between groups but at 3 and 4 years post-DBS the outcome was better in the VIM group (p < 0.01). Stimulation settings were similar across groups, although we found a lower voltage in the VIM group at 3 years post-DBS.

Conclusions

More ventral DBS contacts in the cZI region do improve tremor, however, VIM-DBS provided better long-term outcomes. Randomized controlled trials comparing cZI vs VIM targets should confirm these results.

Report of a patient undergoing chronic responsive deep brain stimulation for Tourette syndrome: proof of concept

Deep brain stimulation (DBS) has emerged as a promising intervention for the treatment of select movement and neuropsychiatric disorders. Current DBS therapies deliver electrical stimulation continuously and are not designed to adapt to a patient's symptoms. Continuous DBS can lead to rapid battery depletion, which necessitates frequent surgery for battery replacement. Next-generation neurostimulation devices can monitor neural signals from implanted DBS leads, where stimulation can be delivered responsively, moving the field of neuromodulation away from continuous paradigms. To this end, the authors designed and chronically implemented a responsive stimulation paradigm in a patient with medically refractory Tourette syndrome. The patient underwent implantation of a responsive neurostimulator, which is capable of responsive DBS, with bilateral leads in the centromedian-parafascicular (Cm-Pf) region of the thalamus. A spectral feature in the 5- to 15-Hz band was identified as the control signal. Clinical data collected prior to and after 12 months of responsive therapy revealed improvements from baseline scores in both Modified Rush Tic Rating Scale and Yale Global Tic Severity Scale scores (64% and 48% improvement, respectively). The effectiveness of responsive stimulation (p = 0.16) was statistically identical to that of scheduled duty cycle stimulation (p = 0.33; 2-sided Wilcoxon unpaired rank-sum t-test). Overall, responsive stimulation resulted in a 63.3% improvement in the neurostimulator's projected mean battery life. Herein, to their knowledge, the authors present the first proof of concept for responsive stimulation in a patient with Tourette syndrome.

Measures of impulsivity in Parkinson's disease decrease after DBS in the setting of stable dopamine therapy

INTRODUCTION

Recent evidence suggests deep brain stimulation can alter impulse control. Our objective was to prospectively evaluate the effects of subthalamic nucleus (STN) and globus pallidus internus (GPi) deep brain stimulation on impulse control disorders (ICDs) in the setting of a conservative dopamine reduction strategy.

METHODS

Patients (n = 37) undergoing de novo, unilateral STN or GPi DBS lead implantation were evaluated pre-operatively and 6-12 months post-operatively for the presence of ICDs using the Questionnaire for Impulsivity in Parkinson's disease (QUIP) and by clinical interview.

RESULTS

Of the patients enrolled, 23 underwent electrode implantation in the globus pallidus internus and 14 were implanted in the subthalamic nucleus. Mean time to long term follow-up was 9.7 ± 2.4 months. Post-operative LEDD was not significantly lower than pre-operative LEDD (pre-op: 1238.53 ± 128.47 vs. post-op: 1178.18 ± 126.43, p = 0.2972, paired t-test). Mean QUIP scores were significantly lower at follow up compared to pre-operative baseline (1.51 ± 0.45 vs. 2.51 ± 0.58, p = 0.0447, paired t-test). Patients with ICDs pre-operatively (n = 14, 37.8%) had significant improvement in QUIP scores at follow-up (6.00 ± 0.94 vs. 2.64 ± 0.98, p = 0.0014, paired t-test). Improvement was not uniform across the cohort: 1 patient with ICD at baseline developed worsening symptoms, and 4 patients with no ICD pre-operatively developed clinically significant ICDs post-operatively.

CONCLUSION

When LEDD is relatively unchanged following STN or GPi DBS for PD, ICD symptoms tend toward improvement, although worsening and emergence of new ICDs can occur. In the setting of stable LEDD, these findings suggest that the intrinsic effects of DBS may play a significant role in altering impulsive behavior.

Motor subtype changes in early Parkinson's disease

INTRODUCTION

Distinct motor subtypes of Parkinson's disease (PD) have been described through both clinical observation and through data-driven approaches. However, the extent to which motor subtypes change during disease progression remains unknown. Our objective was to determine motor subtypes of PD using an unsupervised clustering methodology and evaluate subtype changes with disease duration.

METHODS

The Parkinson's Progression Markers Initiative database of 423 newly diagnosed PD patients was utilized to retrospectively identify unique motor subtypes through a data-driven, hierarchical correlational clustering approach. For each patient, we assigned a subtype to each motor assessment at each follow-up visit (time points) and by using published criteria. We examined changes in PD subtype with disease duration using both qualitative and quantitative methods.

RESULTS

Five distinct motor subtypes were identified based on the motor assessment items and these included: Tremor Dominant (TD), Axial Dominant, Appendicular Dominant, Rigidity Dominant, and Postural and Instability Gait Disorder Dominant. About half of the patients had consistent subtypes at all time points. Most patients met criteria for TD subtype soon after diagnosis. For patients with inconsistent subtypes, there was an overall trend to shift away from a TD phenotype with disease duration, as shown by chi-squared test, p < 0.001, and linear regression analysis, p < 0.05.

CONCLUSION

These results strongly suggest that classification of motor subtypes in PD can shift with increasing disease duration. Shifting subtypes is a factor that should be accounted for in clinical practice or in clinical trials.

Hospitalization and rehospitalization in Parkinson disease patients: Data from the National Parkinson Foundation Centers of Excellence

Background

Patients with Parkinson disease (PD) are at high risk of hospital encounters with increasing morbidity and mortality. This study aimed to determine the rate of hospital encounters in a cohort followed over 5 years and to identify associated factors.

Methods

We queried the data from the International Multicenter National Parkinson Foundation Quality Improvement study. Multivariate logistic regression with backward selection was performed to identify factors associated with hospital encounter prior to baseline visit. Kaplan-Meier estimates were obtained and Cox regression performed on time to hospital encounter after the baseline visit.

Results

Of the 7,507 PD patients (mean age 66.5±9.9 years and disease duration 8.9±6.4 years at baseline visit), 1919 (25.6%) had a history of a hospital encounter prior to their baseline visit. Significant factors associated with a history of a hospital encounter prior to baseline included race (white race: OR 0.49), utilization of physical therapy (OR 1.47), history of deep brain stimulation (OR 1.87), number of comorbidities (OR 1.30), caregiver strain (OR 1.17 per standard deviation), and the standardized Timed Up and Go Test (OR 1.21). Patients with a history of hospitalization prior to the baseline were more likely to have a re-hospitalization (HR1.67, P<0.0001) compared to those without a prior hospitalization. In addition, the time to hospital encounter from baseline was significantly associated with age and number of medications. In patients with a history of hospitalization prior to the baseline visit, time to a second hospital encounter was significantly associated with caregiver strain and number of comorbidities.

Conclusion

Hospitalization and re-hospitalization were common in this cohort of people with PD. Our results suggest addressing caregiver burden, simplifying medications, and emphasizing primary and multidisciplinary care for comorbidities are potential avenues to explore for reducing hospitalization rates.

Focused stimulation of dorsal subthalamic nucleus improves reactive inhibitory control of action impulses

Frontal-basal ganglia circuitry dysfunction caused by Parkinson's disease impairs important executive cognitive processes, such as the ability to inhibit impulsive action tendencies. Subthalamic Nucleus Deep Brain Stimulation in Parkinson's disease improves the reactive inhibition of impulsive actions that interfere with goal-directed behavior. An unresolved question is whether this effect depends on stimulation of a particular Subthalamic Nucleus subregion. The current study aimed to 1) replicate previous findings and additionally investigate the effect of chronic versus acute Subthalamic Nucleus stimulation on inhibitory control in Parkinson's disease patients off dopaminergic medication 2) test whether stimulating Subthalamic Nucleus subregions differentially modulate proactive response control and the proficiency of reactive inhibitory control. In the first experiment, twelve Parkinson's disease patients completed three sessions of the Simon task, Off Deep brain stimulation and medication, on acute Deep Brain Stimulation and on chronic Deep Brain Stimulation. Experiment 2 consisted of 11 Parkinson's disease patients with Subthalamic Nucleus Deep Brain Stimulation (off medication) who completed two testing sessions involving of a Simon task either with stimulation of the dorsal or the ventral contact in the Subthalamic Nucleus. Our findings show that Deep Brain Stimulation improves reactive inhibitory control, regardless of medication and regardless of whether it concerns chronic or acute Subthalamic Nucleus stimulation. More importantly, selective stimulation of dorsal and ventral subregions of the Subthalamic Nucleus indicates that especially the dorsal Subthalamic Nucleus circuitries are crucial for modulating the reactive inhibitory control of motor actions.

Current Practice and the Future of Deep Brain Stimulation Therapy in Parkinson's Disease

Deep brain stimulation (DBS) is an effective therapy for Parkinson's disease patients experiencing motor fluctuations, medication-resistant tremor, and/or dyskinesia. Currently, the subthalamic nucleus and the globus pallidus internus are the two most widely used targets, with individual advantages and disadvantages influencing patient selection. Potential DBS patients are selected using the few existing guidelines and the available DBS literature, and many centers employ an interdisciplinary team review of the individual's risk-benefit profile. Programmed settings vary based on institution- or physician-specific protocols designed to maximize benefits and limit adverse effects. Expectations should be realistic and clearly defined during the evaluation process, and each bothersome symptom should be addressed in the context of building the risk-benefit profile. Current DBS research is focused on improved symptom control, the development of newer technologies, and the improved efficiency of stimulation delivery. Techniques deliver stimulation in a more personalized way, and methods of adaptive DBS such as closed-loop approaches are already on the horizon.

A pilot trial of square biphasic pulse deep brain stimulation for dystonia: The BIP dystonia study

BACKGROUND

Dystonia often has inconsistent benefits and requires more energy-demanding DBS settings. Studies suggest that squared biphasic pulses could provide significant clinical benefit; however, dystonia patients have not been explored.

OBJECTIVES

To assess safety and tolerability of square biphasic DBS in dystonia patients.

METHODS

This study included primary generalized or cervical dystonia patients with bilateral GPi DBS. Square biphasic pulses were implemented and patients were assessed at baseline, immediately postwashout, post-30-minute washout, 1 hour post- and 2 hours postinitiation of investigational settings.

RESULTS

Ten participants completed the study. There were no patient-reported or clinician-observed side effects. There was improvement across time on the Toronto Western Spasmodic Torticollis Rating Scale (χ2  = 10.7; P = 0.031). Similar improvement was detected in objective gait measurements.

CONCLUSIONS

Square biphasic stimulation appears safe and feasible in dystonia patients with GPi DBS. Further studies are needed to evaluate possible effectiveness particularly in cervical and gait features. © 2016 International Parkinson and Movement Disorder Society.

Occurrence of Dysphagia Following Botulinum Toxin Injection in Parkinsonism-related Cervical Dystonia: A Retrospective Study

Background

The aim was to compare the occurrence of post-injection dysphagia in parkinsonism-related cervical dystonia (PRCD) versus cervical dystonia (CD) of other etiologies (non-PRCD). A secondary objective was to explore potential clinical differences between PRCD and non-PRCD and their respective responses to botulinum toxin (BoNT).

Methods

A cross-sectional chart review was carried out of patients treated for CD with Onabotulinumtoxin A at the University of Florida. We collected demographic information, dose of BoNT injected, patient-reported presence of dysphagia as a side effect, patient-perceived duration of benefit and efficacy according to the Clinical Global Impression Scale (CGIS).

Results

Of the 144 patients included, 24 patients were diagnosed with PRCD and 120 were diagnosed as non-PRCD. Data analysis showed no significant differences in number of weeks of benefit from BoNT (PRCD 9.1±3.7 versus non-PRCD 9.4±3.7 weeks, p = 0.830), BoNT dosage (PRCD 235.0±95.6 versus non-PRCD 263.7±101.3 units, p = 0.181), median CGIS score (median = 2 or “much improved” for both groups, p = 0.88), or the presence of dysphagia after BoNT (PRCD 17% versus non-PRCD 19 %, p = 0.753, n = 132). In a subgroup analysis of the non-PRCD group, patients who experienced dysphagia were older than those who did not (63.9±8.9 years versus 58.1±14.4 years, p = 0.02).

Discussion

Despite an increased baseline risk of dysphagia in patients with PRCD, BoNT appears to be equally safe and equally beneficial in PRCD and non-PRCD patients.

Parkinson's disease psychosis: therapy tips and the importance of communication between neurologists and psychiatrists

Parkinson's disease (PD) is a chronic and complex neurodegenerative disorder resulting in a mixture of motor and nonmotor symptoms. Psychosis develops in around 60% of PD patients during and can be one of the most challenging nonmotor symptoms. PD psychosis is considered the single greatest precipitant for nursing home placement. PD psychosis is an independent predictor of increased mortality, and there is no 'ideal' or universal treatment strategy. The treatment approach to PD psychosis should be tailored and individualized for each patient. In this review, we will discuss PD psychosis and provide practical treatment considerations for neurologists, psychiatrists and other healthcare professionals. We stress the importance of real-time communication between members of the healthcare team.

Thalamocortical network activity enables chronic tic detection in humans with Tourette syndrome

Tourette syndrome (TS) is a neuropsychiatric disorder characterized by multiple motor and vocal tics. Deep brain stimulation (DBS) is an emerging therapy for severe cases of TS. We studied two patients with TS implanted with bilateral Medtronic Activa PC + S DBS devices, capable of chronic recordings, with depth leads in the thalamic centromedian-parafascicular complex (CM-PF) and subdural strips over the precentral gyrus. Low-frequency (1-10 Hz) CM-PF activity was observed during tics, as well as modulations in beta rhythms over the motor cortex. Tics were divided into three categories: long complex, complex, and simple. Long complex tics, tics involving multiple body regions and lasting longer than 5 s, were concurrent with a highly detectable thalamocortical signature (average recall [sensitivity] 88.6%, average precision 96.3%). Complex tics were detected with an average recall of 63.9% and precision of 36.6% and simple tics an average recall of 39.3% and precision of 37.9%. The detections were determined using data from both patients.

Depressive Symptoms are Frequent in Atypical Parkinsonian Disorders

OBJECTIVE

To compare the incidence and prevalence of depressive symptoms in atypical parkinsonian (APD) syndromes versus Parkinson disease (PD).

METHODS

In a large retrospective patient cohort we analyzed the incidence and prevalence of depressive symptoms using the Beck Depression Inventory (BDI) and evaluated subjects longitudinally on subsequent visits. For individuals who followed in subsequent visits we calculated incidence rates in person-years as a measure of incidence.

RESULTS

We identified 361 patients with APD including Progressive Supranuclear Palsy (PSP), Corticobasal Degeneration (CBD), Multiple System Atrophy (MSA) and Dementia with Lewy Bodies (DLB), and 2352 PD controls. The mean BDI values were significantly higher in APD (F=14.19, p < 0.001). A significantly higher proportion of APD subjects screened positive for depressive symptoms both at initial and subsequent patient visits (p < 0.001), which appeared to be more severe in the APD subgroups. UPDRS part III and disease duration weakly correlated with depressive symptoms.

CONCLUSIONS

Our results suggest that the incidence and prevalence of depressive symptoms are higher in APD and appear also to be more severe than in PD. Depressive symptoms in APD are common and affect patients regardless of disease duration or motor severity.

Benign tremulous Parkinsonism: a unique entity or another facet of Parkinson's disease?

Benign tremulous parkinsonism (BTP) is characterized by a prominent tremor that occurs both at rest and with action in conjunction with other mild features of parkinsonism. The progression of symptoms is typically slow and there is often a positive family history. Although BTP is included within the phenotypic spectrum of Parkinsonism its exact relationship with idiopathic Parkinson’s disease remains unclear. Treatment of BTP is challenging especially considering the poor response to levodopa, therefore surgical therapies such as deep brain stimulation surgery are sought for treatment of these tremors. In this review, we will summarize the clinical features, diagnosis, neuropathology and treatment for BTP.

Interdisciplinary Parkinson's Disease Deep Brain Stimulation Screening and the Relationship to Unintended Hospitalizations and Quality of Life

Objective

To investigate the impact of pre-operative deep brain stimulation (DBS) interdisciplinary assessments on post-operative hospitalizations and quality of life (QoL).

Background

DBS has been utilized successfully in Parkinson’s disease (PD) for the treatment of tremor, rigidity, bradykinesia, off time, and motor fluctuations. Although DBS is becoming a more common management approach there are no standardized criteria for selection of DBS candidates, and sparse data exist to guide the use of interdisciplinary evaluations for DBS screening. We reviewed the outcomes of the use of an interdisciplinary model which utilized seven specialties to pre-operatively evaluate potential DBS candidates.

Methods

The University of Florida (UF) INFORM database was queried for PD patients who had DBS implantations performed at UF between January 2011 and February 2013. Records were reviewed to identify unintended hospitalizations, falls, and infections. Minor and major concerns or reservations from each specialty were previously documented and quantified. Clinical outcomes were assessed through the use of the Parkinson disease quality of life questionnaire (PDQ-39), and the Unified Parkinson’s Disease Rating Score (UPDRS) Part III.

Results

A total of 164 cases were evaluated for possible DBS candidacy. There were 133 subjects who were approved for DBS surgery (81%) following interdisciplinary screening. There were 28 cases (21%) who experienced an unintended hospitalization within the first 12 months following the DBS operation. The patients identified during interdisciplinary evaluation with major or minor concerns from any specialty service had more unintended hospitalizations (93%) when compared to those without concerns (7%). When the preoperative “concern” shifted from “major” to “minor” to “no concerns,” the rate of hospitalization decreased from 89% to 33% to 3%. A strong relationship was uncovered between worsened PDQ-39 at 12 months and increased hospitalization.

Conclusions

Unintended hospitalizations and worsened QOL scores correlated with the number and severity of concerns raised by interdisciplinary DBS evaluations. The data suggest that detailed screenings by interdisciplinary teams may be useful for more than just patient selection. These evaluations may help to stratify risk for post-operative hospitalization and QoL outcomes.

Post-mortem Findings in Huntington's Deep Brain Stimulation: A Moving Target Due to Atrophy

Background

Deep brain stimulation (DBS) has been shown to be effective for Parkinson’s disease, essential tremor, and primary dystonia. However, mixed results have been reported in Huntington’s disease (HD).

Case Report

A single case of HD DBS was identified from the University of Florida DBS Brain Tissue Network. The clinical presentation, evolution, surgical planning, DBS parameters, clinical outcomes, and brain pathological changes are summarized.

Discussion

This case of HD DBS revealed that chorea may improve and be sustained. Minimal histopathological changes were noted around the DBS leads. Severe atrophy due to HD likely changed the DBS lead position relative to the internal capsule.

Proceedings of the Third Annual Deep Brain Stimulation Think Tank: A Review of Emerging Issues and Technologies

The proceedings of the 3rd Annual Deep Brain Stimulation Think Tank summarize the most contemporary clinical, electrophysiological, imaging, and computational work on DBS for the treatment of neurological and neuropsychiatric disease. Significant innovations of the past year are emphasized. The Think Tank's contributors represent a unique multidisciplinary ensemble of expert neurologists, neurosurgeons, neuropsychologists, psychiatrists, scientists, engineers, and members of industry. Presentations and discussions covered a broad range of topics, including policy and advocacy considerations for the future of DBS, connectomic approaches to DBS targeting, developments in electrophysiology and related strides toward responsive DBS systems, and recent developments in sensor and device technologies.

Randomized, Blinded Pilot Testing of Nonconventional Stimulation Patterns and Shapes in Parkinson's Disease and Essential Tremor: Evidence for Further Evaluating Narrow and Biphasic Pulses

OBJECTIVES

Evidence suggests that nonconventional programming may improve deep brain stimulation (DBS) therapy for movement disorders. The primary objective was to assess feasibility of testing the tolerability of several nonconventional settings in Parkinson's disease (PD) and essential tremor (ET) subjects in a single office visit. Secondary objectives were to explore for potential efficacy signals and to assess the energy demand on the implantable pulse-generators (IPGs).

MATERIALS AND METHODS

A custom firmware (FW) application was developed and acutely uploaded to the IPGs of eight PD and three ET subjects, allowing delivery of several nonconventional DBS settings, including narrow pulse widths, square biphasic pulses, and irregular pulse patterns. Standard clinical rating scales and several objective measures were used to compare motor outcomes with sham, clinically-optimal and nonconventional settings. Blinded and randomized testing was conducted in a traditional office setting.

RESULTS

Overall, the nonconventional settings were well tolerated. Under these conditions it was also possible to detect clinically-relevant differences in DBS responses using clinical rating scales but not objective measures. Compared to the clinically-optimal settings, some nonconventional settings appeared to offer similar benefit (e.g., narrow pulse widths) and others lesser benefit. Moreover, the results suggest that square biphasic pulses may deliver greater benefit. No unexpected IPG efficiency disadvantages were associated with delivering nonconventional settings.

CONCLUSIONS

It is feasible to acutely screen nonconventional DBS settings using controlled study designs in traditional office settings. Simple IPG FW upgrades may provide more DBS programming options for optimizing therapy. Potential advantages of narrow and biphasic pulses deserve follow up.

Deep Brain Stimulation in a Case of Mitochondrial Disease

Background

DBS has proven to be an effective therapy for Parkinson's disease, essential tremor, and primary dystonia. Mixed results have been reported in case series for other hyperkinetic disorders, and sparse data are available regarding secondary movement disorders. We report on the clinical effects of bilateral globus pallidus internus (GPi) DBS, a progressive mitochondrial cytopathy.

Methods

A single patient with myoclonus and dystonia syndrome secondary to a mitochondrial cytopathy with history of perinatal hypoxia was identified from our University of Florida DBS database. Demographics, clinical, surgical, and DBS data were documented.

Results

At 6 months post-DBS, we observed a 32% (361 to 527) improvement on quality of life (36-item Medical Outcome Study Short-Form Health Survey; SF-36). Objective clinical scales revealed a 33% (143 to 96) improvement in the Unified Myoclonus Rating Scale (UMRS) total score. The UMRS action myoclonus subsection revealed a 29% (69 to 46) improvement. No significant changes were observed in the Burke-Fahn-Mardsen Dystonia Rating Scale (BFMDRS). After 1-year follow-up, a worsening of 59% (527 to 215) was observed in the SF-36 scale, of 19% (28.5 to 35) in the BFMDRS, and of 23% (96 to 124) in the UMRS. However, the frequency and intensity of action myoclonus scores remained lower when compared to baseline scores.

Conclusions

Although we observed a loss of benefit in the long term for most quality-of-life and clinical outcomes, the DBS effects on action myoclonus seemed to remain stable. Longer follow-up studies are necessary to confirm our short-term and unblinded findings.

Rate of aspiration pneumonia in hospitalized Parkinson's disease patients: a cross-sectional study

BACKGROUND

Aspiration pneumonia is an important cause of morbidity and mortality in Parkinson's disease (PD). Clinical characteristics of PD patients in addition to specific alterations in swallowing mechanisms contribute to higher swallowing times and impairment in the effective clearance of the airway. These issues may render patients more prone to dysphagia and aspiration events. We aimed to determine the frequency of aspiration events in a hospitalized PD cohort, and to report the number of in-hospital swallow evaluations.

METHODS

A retrospective single center chart review of 212 PD patients who had 339 hospital encounters was performed from January 2011 to March 2013. Demographics, clinical characteristics, and reasons for encounters were documented. The number of in-hospital aspiration events and the number of swallowing evaluations and also the implementation of aspiration precautions were recorded.

RESULTS

The cohort had a mean age of 74.1 (SD = 10.1) years with mean disease duration of 6 (SD = 6.3) years. Fifty-two hospital encounters (15.3%) were related to a pulmonary cause. In-hospital aspiration pneumonia events were reported in 8 (2.4%) of the total encounters. Swallow evaluations were performed in 25% of all cases, and aspiration precautions were initiated in 32% of the encounters. The data revealed that 1/8 patient had swallowing evaluations performed prior to an aspiration event.

CONCLUSIONS

In-hospital aspiration pneumonia events were reported in 2.4% of the hospitalized PD cohort. Preventive measures and precautions were not routinely performed, however rates of aspiration were relatively low. The results highlight the need for more research into screening and monitoring of swallowing problems in PD patients during hospital encounters.

Update on deep brain stimulation in Parkinson's disease

Deep brain stimulation (DBS) is considered a safe and well tolerated surgical procedure to alleviate Parkinson’s disease (PD) and other movement disorders symptoms along with some psychiatric conditions. Over the last few decades DBS has been shown to provide remarkable therapeutic effect on carefully selected patients. Although its precise mechanism of action is still unknown, DBS improves motor functions and therefore quality of life. To date, two main targets have emerged in PD patients: the globus pallidus pars interna and the subthalamic nucleus. Two other targets, the ventralis intermedius and zona incerta have also been selectively used, especially in tremor-dominant PD patients. The main indications for PD DBS have traditionally been motor fluctuations, debilitating medication induced dyskinesias, unpredictable “off time” state, and medication refractory tremor. Medication refractory tremor and intolerable dyskinesia are potential palliative indications. Besides aforementioned targets, the brainstem pedunculopontine nucleus (PPN) is under investigation for the treatment of ON-state freezing of gait and postural instability. In this article, we will review the most recent literature on DBS therapy for PD, including cutting-edge advances and data supporting the role of DBS in advanced neural-network modulation.

Missing dosages and neuroleptic usage may prolong length of stay in hospitalized Parkinson's disease patients

Background

Parkinson’s disease patients are more likely to be hospitalized, have higher rates of hospital complications, and have an increased risk of deterioration during hospitalization. Length of stay is an important underlying factor for these increased risks. We aimed to investigate potential medication errors that may occur during hospitalization and its impact on length of hospital stay.

Methods

A cross-sectional chart review of 339 consecutive hospital encounters from 212 PD subjects was performed. Medication errors were defined as wrong timing or omission of administration for dopaminergic drugs and administration of contraindicated dopamine blockers. An analysis of covariance was applied to examine whether these medication errors were related to increased length of hospital stays.

Results

A significant effect for dopaminergic administration (p<0.01) on length of hospital stay was observed. Subjects who had delayed administration or missed at least one dose stayed longer (M=8.2 days, SD=8.9 vs. M=3.6 days SD=3.4). Contraindicated dopamine blocking agents were administered in 23% (71/339) of cases, and this was also significantly related to an increased length of stay (M=8.2 days, SD=8.9 vs. M=3.6 days SD=3.4), p<0.05. Participants who received a contraindicated dopamine blocker stayed in the hospital longer (M=7.5 days, SD=9.1) compared to those who did not (M=5.9 days, SD=6.8). Neurologists were consulted in 24.5% of encounters. Specialty consultation had no effect on the medication related errors.

Conclusions

Missing dopaminergic dosages and administration of dopamine blockers occur frequently in hospitalized Parkinson’s disease patients and this may impact length of stay. These potentially modifiable factors may reduce the risk of a longer stay related to hospitalization.

Chasing tics in the human brain: development of open, scheduled and closed loop responsive approaches to deep brain stimulation for tourette syndrome

Tourette syndrome is a childhood-onset disorder characterized by a combination of motor and vocal tics, often associated with psychiatric comorbidities including attention deficit and hyperactivity disorder and obsessive-compulsive disorder. Despite an onset early in life, half of patients may present symptoms in adulthood, with variable degrees of severity. In select cases, the syndrome may lead to significant physical and social impairment, and a worrisome risk for self injury. Evolving research has provided evidence supporting the idea that the pathophysiology of Tourette syndrome is directly related to a disrupted circuit involving the cortex and subcortical structures, including the basal ganglia, nucleus accumbens, and the amygdala. There has also been a notion that a dysfunctional group of neurons in the putamen contributes to an abnormal facilitation of competing motor responses in basal ganglia structures ultimately underpinning the generation of tics. Surgical therapies for Tourette syndrome have been reserved for a small group of patients not responding to behavioral and pharmacological therapies, and these therapies have been directed at modulating the underlying pathophysiology. Lesion therapy as well as deep brain stimulation has been observed to suppress tics in at least some of these cases. In this article, we will review the clinical aspects of Tourette syndrome, as well as the evolution of surgical approaches and we will discuss the evidence and clinical responses to deep brain stimulation in various brain targets. We will also discuss ongoing research and future directions as well as approaches for open, scheduled and closed loop feedback-driven electrical stimulation for the treatment of Tourette syndrome.

Comparable Botulinum Toxin Outcomes between Primary and Secondary Blepharospasm: A Retrospective Analysis

Background

Blepharospasm is a focal cranial dystonia, which could be idiopathic in origin or secondary to an underlying disorder that commonly impairs quality of life. Botulinum toxin (BoNT) injections have become the treatment of choice; however, a less favorable response to BoNT is expected in secondary blepharospasm. No studies have been conducted comparing outcomes between blepharospasm cohorts. We therefore aim to compare BoNT outcomes in primary and secondary blepharospasm subjects.

Methods

A retrospective review of 64 blepharospasm subjects receiving BoNT therapy was conducted. Demographics, BoNT treatment schedules, duration of BoNT therapy, and side effects were recorded. Outcome measures were duration of benefit, peak-dose benefit recorded with the Clinical Global Impressions Scale (CGIS), and related side effects.

Results

No difference was found between the two cohorts regarding duration of benefit from treatment (primary 9.47 weeks vs. secondary 9.63 weeks, p = 0.88). Perceived peak-dose benefit was more commonly reported as “very much improved” in secondary patients, but this was not significant (p = 0.13). Higher BoNT dosages were required in both groups over time, with a mean increase of 20.5% in primary and 26.5% in secondary blepharospasm. Ptosis (8%) and diplopia (6%) were the most common reported side effects. Mean follow-up in years was similar between groups, 3.6 years for primary vs. 2.4 years for secondary blepharospasm (p = 0.17).

Discussion

BoNT injections were effective with comparable benefits seen in both primary and secondary blepharospasm populations. Clinicians should be aware of the similar benefit from BoNT reported in secondary blepharospasm patients. The average duration of benefit in this cohort was comparable with previous reports.

Atrophy and other potential factors affecting long term deep brain stimulation response: a case series

OBJECTIVE

To describe three DBS cases which presented with new side effects or loss of benefit from stimulation after long-term follow-up and to discuss the potential contributing factors.

METHODS

A University of Florida (UF) database (INFORM) search was performed, identifying three patients, two Parkinson's disease (PD) and one Essential Tremor (ET), with an unexpected change in long-term programming thresholds as compared to initial evaluation. Clinical follow-up, programming, imaging studies, and lead measurements were reviewed. The UF Institutional Review Board (IRB) approved this study.

RESULTS

A substantial increase in the 3rd ventricular width (120%), Evans index (6%), ventricular index (5%), and cella media index (17%) was uncovered. A change in thresholds across lead contacts with a decrease in current densities as well as a relative lateral change of lead location was also observed. Hardware-related complications, lead migration, and impedance variability were not identified.

CONCLUSIONS

Potential factors contributing to long-term side effects should be examined during a DBS troubleshooting assessment. Clinicians should be aware that in DBS therapy there is delivery of electricity to a changing brain, and atrophy may possibly affect DBS programming settings as part of long-term follow-up.

Rationale and clinical pearls for primary care doctors referring patients for deep brain stimulation

BACKGROUND

Deep brain stimulation (DBS) is a surgical treatment involving the implantation of a brain lead connected to a chest-based neurostimulator similar to a cardiac pacemaker. The device can be programmed to deliver electrical impulses to neuromodulate abnormal brain circuitry in disorders such as Parkinson's disease (PD), essential tremor (ET), and dystonia. As the number of patients receiving DBS surgery increases, it will be important for primary care doctors to identify reasonable DBS candidates for referral to an experienced center.

OBJECTIVE

To provide primary care physicians with a rationale and also to provide clinically useful pearls for referral of potential DBS candidates.

METHODS

A complete PubMed review of the literature.

RESULTS

This review will be focused on PD and ET and will address the following issues: what are the common motor and nonmotor symptoms? What is the evidence supporting the use of DBS in PD and ET? What is the importance of a multi- or interdisciplinary DBS team for patient selection? What can be done to improve success in identifying and referring potential DBS candidates?

CONCLUSION

DBS is a highly effective therapy for select candidates with PD and ET. The most important factor influencing DBS outcome is proper patient selection. It will be critical as DBS continues to be more commonly employed for primary care doctors to select candidates from their practices as appropriate referrals to specialized centers.