Cognition and mood in Parkinson's disease in subthalamic nucleus versus globus pallidus interna deep brain stimulation: the COMPARE trial

The trajectory of apathy after deep brain stimulation: from pre-surgery to 6 months post-surgery in Parkinson's disease

Deep brain stimulation (DBS) has been associated with increased apathy in patients with PD, yet studies lack longitudinal data and have not assessed differences between sites of implantation (i.e. STN versus GPi). We assessed apathy prior to surgery and 6 months post-surgery using a longitudinal design-latent growth curve modeling. We hypothesized that apathy would increase post-surgery, and be related to subthalamic nucleus (versus globus pallidus interna) implantation. Forty-eight PD patients underwent unilateral surgery to either GPi or STN and completed the Apathy Scale prior to surgery and 2, 4, and 6 months post-surgery. Forty-eight matched PD controls completed the Apathy Scale at a 6-month interval. Results indicated apathy increased linearly from pre- to 6-months post-DBS by .66 points bi-monthly, while apathy in the control group did not change. There was no relationship between apathy and DBS site. Higher baseline depression was associated with higher baseline apathy, but not with change in apathy. Middle-aged adults (<65) had a steeper trajectory of apathy than older adults (≥ 65). Apathy trajectory was not related to motor severity, laterality of DBS, levodopa medication reduction, or motor changes after surgery.

Deep brain stimulation emerging indications

There are a number of emerging surgical indications for deep brain stimulation. We have shown that modulation of activity within motor, mood, and cognitive circuits has beneficial effects in patients with Parkinson's disease, treatment-resistant depression, and perhaps Alzheimer's type dementia. We review the rationale, safety, and efficacy for each of these indications, focusing on disease mechanisms and relevant data that are necessary to document therapeutic value in each case. The review closes with some thoughts on possible future directions for deep brain stimulation. It is likely that applications for deep brain stimulation will continue to expand as accumulating data establish its safety and efficacy profile in these and other conditions.

Binge eating in Parkinson's disease: prevalence, correlates and the contribution of deep brain stimulation

Of 96 Parkinson's disease patients surveyed at the University of Florida Movement Disorders Center, one (1%) met diagnostic criteria for binge-eating disorder. Eight (8.3%) exhibited subthreshold binge eating. Psychometric criteria classified problem gambling in 17.8%, hoarding in 8.3%, compulsive buying in 11.5%, hypersexuality in 1.0%, and mania in 1.0% of patients. More overeaters met psychometric criteria for at least one additional impulse-control disorder (67% versus 29%). No more overeaters than non-overeaters were taking a dopamine agonist (44% versus 41%). More overeaters had a history of subthalamic deep brain stimulation (DBS; 44% versus 14%). History of DBS was the only independent predictor of overeating.

Deep brain stimulation for Parkinson disease: an expert consensus and review of key issues

OBJECTIVE

To provide recommendations to patients, physicians, and other health care providers on several issues involving deep brain stimulation (DBS) for Parkinson disease (PD).

DATA SOURCES AND STUDY SELECTION

An international consortium of experts organized, reviewed the literature, and attended the workshop. Topics were introduced at the workshop, followed by group discussion.

DATA EXTRACTION AND SYNTHESIS

A draft of a consensus statement was presented and further edited after plenary debate. The final statements were agreed on by all members.

CONCLUSIONS

(1) Patients with PD without significant active cognitive or psychiatric problems who have medically intractable motor fluctuations, intractable tremor, or intolerance of medication adverse effects are good candidates for DBS. (2) Deep brain stimulation surgery is best performed by an experienced neurosurgeon with expertise in stereotactic neurosurgery who is working as part of a interprofessional team. (3) Surgical complication rates are extremely variable, with infection being the most commonly reported complication of DBS. (4) Deep brain stimulation programming is best accomplished by a highly trained clinician and can take 3 to 6 months to obtain optimal results. (5) Deep brain stimulation improves levodopa-responsive symptoms, dyskinesia, and tremor; benefits seem to be long-lasting in many motor domains. (6) Subthalamic nuclei DBS may be complicated by increased depression, apathy, impulsivity, worsened verbal fluency, and executive dysfunction in a subset of patients. (7) Both globus pallidus pars interna and subthalamic nuclei DBS have been shown to be effective in addressing the motor symptoms of PD. (8) Ablative therapy is still an effective alternative and should be considered in a select group of appropriate patients.

Do patient's get angrier following STN, GPi, and thalamic deep brain stimulation

OBJECTIVE

The objective of the study was to examine whether deep brain stimulation (DBS) of the subthalamic nucleus (STN), the globus pallidus internus (GPi), and/or the ventralis intermedius thalamic nucleus (Vim) was associated with making patients angrier pre to post-surgical intervention.

BACKGROUND

Secondary outcome analysis of the NIH COMPARE Parkinson's Disease DBS trial revealed that participants were angrier and had more mood and cognitive side effects following DBS. Additionally blinded on/off analysis did not change anger scores. The sample size was small but suggested that STN DBS may have been worse than GPi in provoking anger. We endeavored to examine this question utilizing a larger dataset (the UF INFORM database), and also we included a third surgical target (Vim), which has been utilized for a different disease, essential tremor.

METHODS

Consecutive patients from the University of Florida Movement Disorders Center who were implanted with unilateral DBS for Parkinson's disease (STN or GPi) or essential tremor (Vim) were included. Patients originally implanted at outside institutions were excluded. Pre-operative and 4- to 6-month post-operative Visual Analog Mood Scale (VAMS) scores for all three groups were compared; additionally, pre-operative and 1- to 3-month scores were compared for STN and GPi patients. A linear regression model was utilized to analyze the relationship between the VAMS anger score and the independent variables of age, years with symptoms, Mini-Mental Status Examination (MMSE) score, handedness, ethnicity, gender, side of surgery, target of surgery, baseline Dementia Rating Scale (DRS) total score, baseline Beck Depression Index (BDI) score, micro- and macroelectrode passes, and years of education. Levodopa equivalent dosages and dopamine agonist use were analyzed for a potential impact on anger scores.

RESULTS

A total of 322 unilateral DBS procedures were analyzed, with STN (n=195), Vim (n=71), and GPi (n=56) making up the cohort. An ANOVA was used to detect significant differences among the three targets in the changes pre- to post-operatively. Similar to the COMPARE dataset, at 4 months, the only subscore of VAMS to reveal a significant difference between the three targets was the angry subscore, with GPi revealing a mean (standard) change of 2.38 (9.53); STN, 4.82 (14.52); and Vim, -1.17 (11.51) (p=0.012). At 1-3 months post-operation, both STN and GPi groups were significantly angrier (p=0.004), but there was no significant difference between the two groups. However, GPi patients were significantly more confused as compared to STN patients (p=0.016). The linear regression model which sought independent explanatory variables revealed a relationship between the VAMS anger score and the surgical target and the disease duration. The mean changes for STN and GPi DBS pre- to post-operation were 11.67 (p=0.001) and 8.21 (p=0.022) units more than those with Vim, respectively. For every year added of disease duration, the VAMS anger score increased by 0.24 (p=0.022). For the GPi and STN groups, number of microelectrode passes was significantly associated with angry score changes (p=0.014), with the anger score increasing 2.29 units per microelectrode pass. Independent variables not associated with the VAMS anger score included the surgery side, handedness, gender, ethnicity, education, age at surgery, MMSE, DRS, and BDI scores. Although the STN group significantly decreased in LED when compared to GPi, there was no relationship to anger scores. Similarly, dopamine agonist use was not different between STN and GPi groups and did not correlate with the VAMS anger score changes.

CONCLUSIONS

STN and GPi DBS for Parkinson's disease were associated with significantly higher anger scores pre- to post-DBS as compared to Vim for essential tremor. Anger score changes in STN and GPi patients seem to be associated with microelectrode passes, suggesting that it may be a lesional effect. PD patients with longer disease duration may be particularly susceptible, and this should be kept in mind when discussing the potential of DBS surgery for an individual patient. Essential tremor patients who on average have much longer disease durations did not get angrier. The changes in anger scores were not related to LED change or dopamine agonist use. Whether the induction of anger is disease-specific or target-specific is not currently known; however, our data would suggest that PD patients implanted in STN or GPi are at a potential risk. Finally, on closer inspection of the COMPARE DBS data, VAMS anger scores did not change on or off DBS, suggesting that anger changes may be more of a lesional effect rather than a stimulation induced one (Okun et al., 2009).

Speech motor program maintenance, but not switching, is enhanced by left-hemispheric deep brain stimulation in Parkinson's disease

Speech reaction time (SRT) was measured in a response priming protocol in 12 participants with Parkinson's disease (PD) and hypokinetic dysarthria "on" and "off" left-hemispheric deep brain stimulation (DBS). Speech preparation was measured during speech motor programming in two randomly ordered speech conditions: speech maintenance and switching. Double blind testing was completed in participants with DBS of globus pallidus pars interna (GPi) (n = 5) or subthalamic nucleus (STN) (n = 7). SRT was significantly faster in the maintenance vs switch task, regardless of DBS state. SRT was faster in the speech maintenance task "on" stimulation, while there was no difference in speech switching "on" and "off" DBS. These data suggest that left-hemispheric DBS may have differential effects on aspects of speech preparation in PD. It is hypothesized that speech maintenance improvements may result from DBS-induced cortical enhancements, while the lack of difference in switching may be related to inhibition deficits mediated by the right-hemisphere. Alternatively, DBS may have little influence on the higher level motor processes (i.e., motor planning) which it is believed the switch task engaged to a greater extent than the maintenance task.

A closer look at unilateral versus bilateral deep brain stimulation: results of the National Institutes of Health COMPARE cohort

OBJECT

In this paper, the authors' aim was to examine reasons underpinning decisions to undergo, or alternatively forgo, a second-sided deep brain stimulation (DBS) implantation in patients with Parkinson disease (PD).

METHODS

Fifty-two patients with Parkinson disease (PD) were randomized to receive DBS to the subthalamic nucleus or globus pallidus internus (GPi) as part of the COMPARE trial. Forty-four patients had complete data sets. All patients were offered a choice at 6 months after unilateral implantation whether to receive a contralateral DBS implant. All patients had advanced PD. The mean patient age was 59.8 years (range 43-76 years), and the mean duration of disease was 12.2 years (range 5-21 years). The mean baseline Unified Parkinson's Disease Rating Scale (UPDRS)-III motor score was 42.7. The main outcome measures used in this study were the UPDRS-III Motor Scale and the UPDRS-IV Dyskinesia Scale.

RESULTS

Twenty-one (48%) of the 44 patients in the cohort did not undergo bilateral implantation and have been successfully treated for an average of 3.5 years; of these, 14 (67%) had a GPi target. The most common reason for adding a second side was inadequacy to address motor symptoms. Patient satisfaction with motor outcomes after unilateral DBS implantation was the most common reason for not undergoing bilateral implantation. Those who chose a second DBS procedure had significantly higher baseline UPDRS-III motor and ipsilateral UPDRS-III scores, and a significantly lower asymmetrical index. The logistic regression analysis revealed that the odds of proceeding to bilateral DBS was 5.2 times higher for STN than for GPi DBS. For every 1% increase in asymmetry, the odds of bilateral DBS decreased [corrected] by 0.96.

CONCLUSIONS

Unilateral DBS is an effective treatment for a subset of patients with PD. Baseline asymmetry is an important factor in the effectiveness and decision-making process between unilateral and bilateral DBS. Patients with GPi DBS in this cohort were more likely to choose to remain with unilateral implantation.

Disrupting abnormal electrical activity with deep brain stimulation: is epilepsy the next frontier?

Given the tremendous success of deep brain stimulation (DBS) for the treatment of movement and neuropsychiatric disorders, clinicians have begun to open up to the possible use of electrical stimulation for the treatment of patients with uncontrolled seizures. This process has resulted in the discovery of a wide array of DBS targets, including the cerebellum, hypothalamus, hippocampus, basal ganglia, and various thalamic nuclei. Despite the ambiguity of the mechanism of action and the unknowns surrounding potentially ideal stimulation settings, several recent trials have empirically demonstrated reasonable efficacy in selected cases of medication-refractory seizures. These exciting results have fueled a number of studies aimed at firmly establishing DBS as an effective treatment for selected cases of intractable epilepsy, and many companies are aiming at Food and Drug Administration approval. We endeavor to review the studies in the context of the various DBS targets and their relevant circuitry for epilepsy. Based on the unfolding research, DBS has the potential to play an important role in treating refractory epilepsy. The challenge, as in movement disorders, is to assemble interdisciplinary teams to screen, implant, and follow patients, and to clarify patient selection. The future will undoubtedly be filled with optimization of targets and stimulation parameters and the development of best practices. With tailored therapeutic approaches, epilepsy patients have the potential to improve with DBS.

Cognitive and neuropsychiatric effects of subthalamotomy for Parkinson's disease

Since the advent of deep brain stimulation (DBS) for the treatment of Parkinson's disease (PD), subsequent cognitive and neuropsychiatric effects of this procedure have become well-chronicled. Yet, thermolitic lesion of the subthalamic nucleus (STN) is still a valid option when DBS cannot be applied, and little has been published regarding its impact on cognition and mood. We examined the cognitive and neuropsychiatric functions of 10 consecutive patients with advanced PD undergoing simultaneous bilateral subthalamotomies. With 24 months of follow-up, the patients, three of whom were on anticholinergics prior to surgery, showed no deterioration in cognitive assessments including verbal fluency. Hypoactive behaviors (depression and apathy) showed lasting improvement, while hyperactive behaviors (euphoria and disinhibition) transiently increased after surgery. Improvement in hypoactive behaviors correlated with improvement in hypokinetic movements, and enhanced hyperactive behaviors followed the course of post-operative hyperkinetic movements. Such correlations may support the role of the STN in modulating limbic connections between the basal ganglia and frontal cortex. The results of this proof-of-concept pilot study suggest the need for larger, long-term, randomized controlled studies to assess motor, neuropsychiatric, behavioral and radiologic correlations after subthalamotomies.

From the cell to the clinic: a comparative review of the partial D₂/D₃receptor agonist and α2-adrenoceptor antagonist, piribedil, in the treatment of Parkinson's disease

Though L-3,4-dihydroxyphenylalanine (L-DOPA) is universally employed for alleviation of motor dysfunction in Parkinson's disease (PD), it is poorly-effective against co-morbid symptoms like cognitive impairment and depression. Further, it elicits dyskinesia, its pharmacokinetics are highly variable, and efficacy wanes upon long-term administration. Accordingly, "dopaminergic agonists" are increasingly employed both as adjuncts to L-DOPA and as monotherapy. While all recognize dopamine D(2) receptors, they display contrasting patterns of interaction with other classes of monoaminergic receptor. For example, pramipexole and ropinirole are high efficacy agonists at D(2) and D(3) receptors, while pergolide recognizes D(1), D(2) and D(3) receptors and a broad suite of serotonergic receptors. Interestingly, several antiparkinson drugs display modest efficacy at D(2) receptors. Of these, piribedil displays the unique cellular signature of: 1), signal-specific partial agonist actions at dopamine D(2)and D(3) receptors; 2), antagonist properties at α(2)-adrenoceptors and 3), minimal interaction with serotonergic receptors. Dopamine-deprived striatal D(2) receptors are supersensitive in PD, so partial agonism is sufficient for relief of motor dysfunction while limiting undesirable effects due to "over-dosage" of "normosensitive" D(2) receptors elsewhere. Further, α(2)-adrenoceptor antagonism reinforces adrenergic, dopaminergic and cholinergic transmission to favourably influence motor function, cognition, mood and the integrity of dopaminergic neurones. In reviewing the above issues, the present paper focuses on the distinctive cellular, preclinical and therapeutic profile of piribedil, comparisons to pramipexole, ropinirole and pergolide, and the core triad of symptoms that characterises PD-motor dysfunction, depressed mood and cognitive impairment. The article concludes by highlighting perspectives for clarifying the mechanisms of action of piribedil and other antiparkinson agents, and for optimizing their clinical exploitation.

Pallidal versus subthalamic deep-brain stimulation for Parkinson's disease

BACKGROUND

Deep-brain stimulation is the surgical procedure of choice for patients with advanced Parkinson's disease. The globus pallidus interna and the subthalamic nucleus are accepted targets for this procedure. We compared 24-month outcomes for patients who had undergone bilateral stimulation of the globus pallidus interna (pallidal stimulation) or subthalamic nucleus (subthalamic stimulation).

METHODS

At seven Veterans Affairs and six university hospitals, we randomly assigned 299 patients with idiopathic Parkinson's disease to undergo either pallidal stimulation (152 patients) or subthalamic stimulation (147 patients). The primary outcome was the change in motor function, as blindly assessed on the Unified Parkinson's Disease Rating Scale, part III (UPDRS-III), while patients were receiving stimulation but not receiving antiparkinsonian medication. Secondary outcomes included self-reported function, quality of life, neurocognitive function, and adverse events.

RESULTS

Mean changes in the primary outcome did not differ significantly between the two study groups (P=0.50). There was also no significant difference in self-reported function. Patients undergoing subthalamic stimulation required a lower dose of dopaminergic agents than did those undergoing pallidal stimulation (P=0.02). One component of processing speed (visuomotor) declined more after subthalamic stimulation than after pallidal stimulation (P=0.03). The level of depression worsened after subthalamic stimulation and improved after pallidal stimulation (P=0.02). Serious adverse events occurred in 51% of patients undergoing pallidal stimulation and in 56% of those undergoing subthalamic stimulation, with no significant between-group differences at 24 months.

CONCLUSIONS

Patients with Parkinson's disease had similar improvement in motor function after either pallidal or subthalamic stimulation. Nonmotor factors may reasonably be included in the selection of surgical target for deep-brain stimulation. (ClinicalTrials.gov numbers, NCT00056563 and NCT01076452.)

Speech and Cognitive-Linguistic Function in Parkinson's Disease

Purpose: Parkinson's disease is among the most common of the motor-based progressive neurologic disorders. This article provides a review of the motor, cognitive, sensory-perceptual, and linguistic deficits that may occur as a result of the loss of dopaminergic neurons, which causes Parkinson's disease.

Method: A review of the literature regarding the nature of Parkinson's disease points out the primary triad of symptoms, which are tremor, rigidity, and bradykinesia. Descriptions of these cardinal symptoms are discussed, as are the non-motor symptoms frequently seen in this disorder, including cognitive changes, sensory-perceptual deficits, and occasionally, linguistic deficits. Dysarthria and dysphagia are frequently seen as a result of the motor deficits associated with Parkinson's disease.

Conclusions: Much has been learned about the pathogenesis of Parkinson's disease, which has led to improved pharmacologic, surgical, and behavioral management. Speech-language pathologists (SLPs) need to be aware of these advances in order to better assess and treat patients and educate families.

Deep brain stimulation of pedunculopontine tegmental nucleus (PPTg) promotes cognitive and metabolic changes: a target-specific effect or response to a low-frequency pattern of stimulation?

Deep brain stimulation (DBS) is a reliable treatment for advanced Parkinson's disease (PD) patients, but a possible risk of worsening cognitive functions, although modest, may postpone or halt DBS clinical indication. In a small cohort of PD patients we have pioneered the simultaneous implantation of both the subthalamic nucleus (STN) and the pedunculopontine tegmental nucleus (PPTg). Here we describe the cognitive test performance and the corresponding cortical metabolic activity, as assessed through 18-fluorodeoxyglucose (FDG)-positron emission tomography (PET), of these six PD patients tested in PPTg-ON vs- PPTg-OFF condition. PPTg-ON condition (at low frequency, 25 Hz) induced better performance in tests exploring both executive and attentive domains, which were coupled with an increased glucose utilization in prefrontal and frontal bilateral cortical areas, including both lateral (i.e., BA9) and more antero-medial cortices (BA 25-32). Moreover, during PPTg-ON, a surprising increase of FDG consumption was also observed in the left ventral striatum. These data are consistent with the hypothesis of a positive effect of 25 Hz PPTg-DBS on PD patients' cognitive profile, probably due to a facilitatory effect exerted by PPTg on both associative and limbic pathways.

Patient-specific analysis of the relationship between the volume of tissue activated during DBS and verbal fluency

Deep brain stimulation (DBS) for the treatment of advanced Parkinson's disease involves implantation of a lead with four small contacts usually within the subthalamic nucleus (STN) or globus pallidus internus (GPi). While generally safe from a cognitive standpoint, STN DBS has been commonly associated with a decrease in the speeded production of words, a skill referred to as verbal fluency. Virtually all studies comparing presurgical to postsurgical verbal fluency performance have detected a decrease with DBS. The decline may be attributable in part to the surgical procedures, yet the relative contributions of stimulation effects are not known. In the present study, we used patient-specific DBS computer models to investigate the effects of stimulation on verbal fluency performance. Specifically, we investigated relationships of the volume and locus of activated STN tissue to verbal fluency outcome. Stimulation of different electrode contacts within the STN did not affect total verbal fluency scores. However, models of activation revealed subtle relationships between the locus and volume of activated tissue and verbal fluency performance. At ventral contacts, more tissue activation inside the STN was associated with decreased letter fluency performance. At optimal contacts, more tissue activation within the STN was associated with improved letter fluency performance. These findings suggest subtle effects of stimulation on verbal fluency performance, consistent with the functional nonmotor subregions/somatotopy of the STN.

Therapy for dyskinesias in Parkinson’s disease patients

Dyskinesia hampers the quality of life for most Parkinson’s disease patients following several years of therapy. However, the severity of L-Dopa-induced dyskinesia (LID) varies between patients, being quite tolerable in late-onset patients. Understanding the pathogenesis of LID has contributed to the development of a set of therapeutic strategies, including the choice, in early stages, of the least pulsatile regimen of dopamine-receptor activation. In cases where LIDs are already disabling, there is only a limited number of options: the optimization of ongoing DOPA-centered treatment, the utilization of glutamate antagonists and the exploration of the benefits of antipsychotic agents. More radical solutions are provided by deep brain stimulation in the subthalamic nucleus (or internal pallidus). This approach has proved efficacious in reducing LID, largely because it allows a reduction in dopaminergic daily doses. Stereotactic neurosurgery has fuelled several lines of investigation regarding the crosstalk between the basal ganglia and motor cortex. Here, we will present interesting evidence highlighting the potential for repetitive transcranial stimulation in reducing the occurrence of LID. The future may disclose important new avenues for the treatment of LIDs, given the current development of promising agents that might target different facets of dyskinesia, such as the impairment of striatal plasticity and non-Dopaminergic contributors such as adenosine, nitric oxide and the nucleotide cascade.

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.

Deep brain stimulation in Parkinson's disease

During the last 15 years deep brain stimulation (DBS) has been established as a highly-effective therapy for advanced Parkinson's disease (PD). Patient selection, stereotactic implantation, postoperative stimulator programming and patient care requires a multi-disciplinary team including movement disorders specialists in neurology and functional neurosurgery. To treat medically refractory levodopa-induced motor complications or resistant tremor the preferred target for high-frequency DBS is the subthalamic nucleus (STN). STN-DBS results in significant reduction of dyskinesias and dopaminergic medication, improvement of all cardinal motor symptoms with sustained long-term benefits, and significant improvement of quality of life when compared with best medical treatment. These benefits have to be weighed against potential surgery-related adverse events, device-related complications, and stimulus-induced side effects. The mean disease duration before initiating DBS in PD is currently about 13 years. It is presently investigated whether the optimal timing for implantation may be at an earlier disease-stage to prevent psychosocial decline and to maintain quality of life for a longer period of time.