Medication dose reductions after pallidal versus subthalamic stimulation in patients with Parkinson's disease

Deep brain stimulation: Challenges at the tissue-electrode interface and current solutions

Deep brain stimulation (DBS) is used to treat the motor symptoms of Parkinson's disease patients by stimulating the subthalamic nucleus. However, optimization of DBS is still needed since the performance of the neural electrodes is limited by the body's response to the implant. This review discusses the issues with DBS, such as placement of electrodes, foreign body response, and electrode degradation. The current solutions to these technical issues include modifications to electrode material, coatings, and geometry.

Kinesthetic Cells within the Subthalamic Nucleus and Deep Brain Stimulation for Parkinson Disease

OBJECTIVE

We sought to determine the location of kinesthetic cell clusters within the subthalamic nucleus (STN) on magnetic resonance imaging, adjusted for interindividual anatomic variability by employing the medial STN border as a reference point.

METHODS

We retrospectively localized microelectrode recording-defined kinesthetic cells on 3-Tesla T2-weighted and susceptibility-weighted images in patients who underwent STN deep brain stimulation for Parkinson disease and averaged the stereotactic coordinates. These locations were calculated relative to the nonindividualized midcommissural point (MCP) and, in order to account for interindividual anatomic variability, also calculated relative to the patient-specific intersection of Bejjani line with the medial STN border. Two example patients were selected in order to visualize the discrepancies between the adjusted and nonadjusted theoretic kinesthetic cell clusters on magnetic resonance imaging.

RESULTS

Relative to the MCP, average kinesthetic cell coordinates were 12.3 ± 1.2 mm lateral, 1.7 ± 1.4 mm posterior, and 2.3 ± 1.5 mm inferior. Relative to the medial STN border, mean coordinates were 3.4 ± 1.0 mm lateral, 1.0 ± 1.4 mm anterior, and 1.7 ± 1.5 mm superior on T2-sequences, and on susceptibility-weighted images mean coordinates were 3.2 ± 1.1 mm lateral, 0.8 ± 1.5 mm anterior, and 2.1 ± 1.5 mm superior. The theoretic kinesthetic cell clusters may appear outside the sensorimotor STN when using the MCP, whereas these clusters fall well within the sensorimotor STN when employing the medial STN border as a reference point.

CONCLUSIONS

By using the medial STN border as a patient-specific anatomic reference point in STN deep brain stimulation for Parkinson disease, we accounted for interindividual anatomic variability and provided accurate insight in the clustering of kinesthetic cells within the dorsolateral STN.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guideline on Subthalamic Nucleus and Globus Pallidus Internus Deep Brain Stimulation for the Treatment of Patients With Parkinson's Disease: Executive Summary

QUESTION 1

Is bilateral subthalamic nucleus deep brain stimulation (STN DBS) more, less, or as effective as bilateral globus pallidus internus deep brain stimulation (GPi DBS) in treating motor symptoms of Parkinson's disease, as measured by improvements in Unified Parkinson's Disease Rating Scale, part III (UPDRS-III) scores?

RECOMMENDATION

Given that bilateral STN DBS is at least as effective as bilateral GPi DBS in treating motor symptoms of Parkinson's disease (as measured by improvements in UPDRS-III scores), consideration can be given to the selection of either target in patients undergoing surgery to treat motor symptoms. (Level I).

QUESTION 2

Is bilateral STN DBS more, less, or as effective as bilateral GPi DBS in allowing reduction of dopaminergic medication in Parkinson's disease?

RECOMMENDATION

When the main goal of surgery is reduction of dopaminergic medications in a patient with Parkinson's disease, then bilateral STN DBS should be performed instead of GPi DBS. (Level I).

QUESTION 3

Is bilateral STN DBS more, less, or as effective as bilateral GPi DBS in treating dyskinesias associated with Parkinson's disease?

RECOMMENDATION

There is insufficient evidence to make a generalizable recommendation regarding the target selection for reduction of dyskinesias. However, when the reduction of medication is not anticipated and there is a goal to reduce the severity of "on" medication dyskinesias, the GPi should be targeted. (Level I).

QUESTION 4

Is bilateral STN DBS more, less, or as effective as bilateral GPi DBS in improving quality of life measures in Parkinson's disease?

RECOMMENDATION

When considering improvements in quality of life in a patient undergoing DBS for Parkinson's disease, there is no basis to recommend bilateral DBS in 1 target over the other. (Level I).

QUESTION 5

Is bilateral STN DBS associated with greater, lesser, or a similar impact on neurocognitive function than bilateral GPi DBS in Parkinson disease?

RECOMMENDATION

If there is significant concern about cognitive decline, particularly in regards to processing speed and working memory in a patient undergoing DBS, then the clinician should consider using GPi DBS rather than STN DBS, while taking into consideration other goals of surgery. (Level I).

QUESTION 6

Is bilateral STN DBS associated with a higher, lower, or similar risk of mood disturbance than GPi DBS in Parkinson's disease?

RECOMMENDATION

If there is significant concern about the risk of depression in a patient undergoing DBS, then the clinician should consider using pallidal rather than STN stimulation, while taking into consideration other goals of surgery. (Level I).

QUESTION 7

Is bilateral STN DBS associated with a higher, lower, or similar risk of adverse events compared to GPi DBS in Parkinson's disease?

RECOMMENDATION

There is insufficient evidence to recommend bilateral DBS in 1 target over the other in order to minimize the risk of surgical adverse events.  The full guideline can be found at: https://www.cns.org/guidelines/deep-brain-stimulation-parkinsons-disease.

Subthalamic nucleus and globus pallidus internus stimulation for the treatment of Parkinson's disease: A systematic review

Objective

Deep brain stimulation (DBS) for treatment of advanced Parkinson’s disease (PD) has two anatomical targets: the subthalamic nucleus (STN) and the globus pallidus internus (GPI). The clinical effectiveness of these two stimulation targets was compared in the present study.

Methods

A systematic review and meta-analysis was performed to evaluated the postoperative changes in the United Parkinson’s Disease Rating Scale (UPDRS) on- and off-phase, on-stimulation motor scores; activities of daily living score (ADLS); and levodopa equivalent dose (LED) after STN and GPI stimulation. Randomized and nonrandomized controlled trials of PD treated by STN and GPI stimulation were considered for inclusion.

Results

Eight published reports of eligible studies involving 599 patients met the inclusion criteria. No significant differences were observed between the STN and GPI groups in the on-medication, on-stimulation UPDRS motor score [mean difference, 2.15; 95% confidence interval (CI), −0.96–5.27] or ADLS (mean difference, 3.40; 95% CI, 0.95–7.76). Significant differences in favor of STN stimulation were noted in the off-medication, on-stimulation UPDRS motor score (mean difference, 1.67; 95% CI, 0.98–2.37) and LED (mean difference, 130.24; 95% CI, 28.82–231.65).

Conclusion

The STN may be the preferred target for DBS in consideration of medication reduction, economic efficiency, and motor function improvement in the off phase. However, treatment decisions should be made according to the individual patient’s symptoms and expectations.

Revision Surgery of Deep Brain Stimulation Leads

INTRODUCTION

Deep brain stimulation (DBS) is widely used for various movement disorders. DBS lead revisions are becoming more common as the indications and number of cases increases.

METHODS

Patients undergoing DBS lead revisions at a single institution were retrospectively analyzed based on diagnosis, reason for revision, where the lead was relocated, and surgical technique.

RESULTS

We reviewed 497 consecutive DBS lead placements and found that there was need for 25 DBS lead revisions with at least six months of follow-up. Loss of efficacy and development of adverse effects over time were the most common reasons for lead revision across all diagnosis. Lead malfunction was the least common. Ten patients requiring 19 DBS lead revisions that underwent their original surgery at another institution were also analyzed. Surgical technique dictated replacing with a new lead while maintaining brain position and tract with the old lead until final placement. Methods to seal exposed wire were developed.

CONCLUSION

Surgical technique, as well as variable options are important in lead revision and can be dictated based on reason for revision. Over time patients who have had adequate relief with DBS placement may experience loss of efficacy and development of adverse effects requiring revision of the DBS lead to maintain its effects.

Progression and survival in Parkinson's disease with subthalamic nucleus stimulation

BACKGROUND

Treatment for Parkinson's disease (PD) is symptomatic. Surgical treatment with continuous high-frequency stimulation of the subthalamic nucleus (STN-DBS) is established as a safe symptomatic treatment with long-term beneficial effects. It has been postulated that STN-DBS could halt the progression of PD through a disease modifying or neuroprotective effect.

OBJECTIVE

To investigate the postulated disease modifying or neuroprotective effect of STN-DBS by comparing the rate of deterioration of parkinsonism and mortality over time in two selected and matched groups of patients with PD with and without surgery.

METHODS

Group A was derived from all patients who received STN-DSB surgery at Oslo University Hospital, from January 2001 to December 2007. Group B was derived from a prevalence study of PD in the Stavanger area of Western Norway in 1993. The two groups were individually matched and the disease progression measured by Unified Parkinson's Disease Rating Scale-motor scores, and the mortality was compared.

RESULTS

The mean annual change based on baseline and last observation scores in individually matched groups was 0.97 (SD = 3.57) for the surgery group and 1.04 (SD = 3.33) for the controls and thus not significantly different, F(1, 104) = .21, P = 0.89. The long-term mortality was also similar in the two groups during long-term follow-up, hazard ratio = 1.76, CL 0.91-3.40, P = 0.091.

CONCLUSION

This study gives no support to a postulated disease modifying or neuroprotective effect of STN-DBS in patients with PD.

Timing of deep brain stimulation in Parkinson disease: a need for reappraisal?

We review the current application of deep brain stimulation (DBS) in Parkinson disease (PD) and consider the evidence that earlier use of DBS confers long-term symptomatic benefit for patients compared to best medical therapy. Electronic searches were performed of PubMed, Web of Knowledge, Embase, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials to identify all article types relating to the timing of DBS in PD. Current evidence suggests that DBS is typically performed in late stage PD, a mean of 14 to 15 years after diagnosis. Current guidelines recommend that PD patients who are resistant to medical therapies, have significant medication side effects and lengthening off periods, but are otherwise cognitively intact and medically fit for surgery be considered for DBS. If these criteria are rigidly interpreted, it may be that, by the time medical treatment options have been exhausted, the disease has progressed to the point that the patient may no longer be fit for neurosurgical intervention. From the evidence available, we conclude that surgical management of PD alone or in combination with medical therapy results in greater improvement of motor symptoms and quality of life than medical treatment alone. There is evidence to support the use of DBS in less advanced PD and that it may be appropriate for earlier stages of the disease than for which it is currently used. The improving short and long-term safety profile of DBS makes early application a realistic possibility.

Drug-induced dyskinesia in Parkinson's disease. Should success in clinical management be a function of improvement of motor repertoire rather than amplitude of dyskinesia?

BACKGROUND

Dyskinesia, a major complication in the treatment of Parkinson's disease (PD), can require prolonged monitoring and complex medical management.

DISCUSSION

The current paper proposes a new way to view the management of dyskinesia in an integrated fashion. We suggest that dyskinesia be considered as a factor in a signal-to-noise ratio (SNR) equation where the signal is the voluntary movement and the noise is PD symptomatology, including dyskinesia. The goal of clinicians should be to ensure a high SNR in order to maintain or enhance the motor repertoire of patients. To understand why such an approach would be beneficial, we first review mechanisms of dyskinesia, as well as their impact on the quality of life of patients and on the health-care system. Theoretical and practical bases for the SNR approach are then discussed.

SUMMARY

Clinicians should not only consider the level of motor symptomatology when assessing the efficacy of their treatment strategy, but also breadth of the motor repertoire available to patients.

Functional neurosurgery in Parkinson's disease: a long journey from destruction over modulation towards restoration

Neurosurgical treatment of Parkinson's disease (PD) has re-gained considerable attention over the last two decades due to a better understanding of the pathophysiology of the basal ganglia, the long-term complications of medical treatment, and advances in neuroimaging and neurosurgical techniques. The introduction of deep brain stimulation (DBS) has created new perspectives for the surgical management of PD patients, due to the low morbidity, reversibility and improvement of both motor function and quality of life as compared to the lesioning techniques. We present an overview of basic principles, history, indications, and results of current neurosurgical techniques available in PD.

Effects of repeated deep brain stimulation on depressive- and anxiety-like behavior in rats: comparing entopeduncular and subthalamic nuclei

BACKGROUND

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) or internal globus pallidus (GPi) has been routinely used for the treatment of some movement disorders. However, DBS may be associated with adverse psychiatric effects, such as depression, anxiety and impulsivity.

OBJECTIVE

To compare DBS applied to the entopeduncular nucleus (EPN; the rodent homolog of the GPi) and STN in terms of their effects on depressive- and anxiety-like behavior in rats.

METHODS

DBS was applied for 21 days (4 h a day) to either the STN or EPN. Rats then underwent behavioral testing on learned helplessness and elevated plus maze tasks before being sacrificed for brain analyses of zif268, BDNF and trkB mRNA as well as BDNF protein levels.

RESULTS

Repeated DBS of the STN, but not of the EPN, led to impaired performance in the learned helplessness task, suggesting that STN-DBS induces or potentiates depressive-like behavior. There was no effect of DBS on elevated plus maze or on open field behavior. Repeated STN-DBS, but not EPN-DBS, led to decreased levels of BDNF and trkB mRNA in hippocampus. Acute stimulation of the STN or EPN resulted in similar changes in zif268 levels in several brain areas, except for the raphe where decreases were seen only after STB-DBS.

CONCLUSIONS

Together these results indicate that the effects of STN- and EPN-DBS differ in behavioral and neurochemical respects. Results further suggest that the EPN may be a preferable target for clinical DBS when psychiatric side effects are considered insofar as it may be associated with a lower incidence of depressive-like behavior than the STN.

Deep brain stimulation of globus pallidus interna, subthalamic nucleus, and pedunculopontine nucleus for Parkinson's disease: which target?

Deep brain stimulation (DBS) is an accepted therapy for people with Parkinson's disease (PD) motor symptoms that are refractory to pharmacologic therapy. Standard DBS targets are globus pallidus interna (GPi) and subthalamic nucleus (STN). The pedunculopontine nucleus (PPN) is being investigated as a novel target. Which target provides the best outcomes is unknown. The utility of GPi and STN as targets has been confirmed in numerous studies, including randomized comparisons of GPi DBS and STN DBS that demonstrated no difference in motor outcomes. DBS at either site improves appendicular motor symptoms, but beneficial effects on axial manifestations of PD such as postural instability or gait dysfunction (PIGD) are less apparent. PPN has been introduced as a DBS target due to failure of GPi and STN DBS to improve PIGD. Small observational studies indicate improved PIGD with PPN DBS, but small blinded trials show only subjective reduction in falls with no other impact on PIGD or other PD manifestations. No single DBS target is superior to the others. Each target offers relative advantages. Further studies are needed to better define the roles of each target, particularly PPN. Choice of target should be individualized according to providers' preferences and patients' needs.

Heart rate variability in Parkinson's disease unaffected by deep brain stimulation

OBJECTIVES

Our aim was to investigate the impact of subthalamic nucleus deep brain stimulation (STN-DBS) on the cardiovagal control of patients with advanced Parkinson's disease.

MATERIALS AND METHODS

Twenty-four patients (mean age: 62.1 ± 9.4 years) were examined 3 days before and 6 months after DBS by a questionnaire, blood pressure monitoring and a battery of neurophysiological tests: time domain analysis of RR interval variation during normal and deep breathing (DB), Valsalva manoeuvre, and tilt test. By off-line, performed frequency domain analysis of heart rate variation, total power (TP), low frequency band (LF) band, high-frequency (HF) band, and their normalized units were estimated. The neurophysiological measurements were compared to those of 24 healthy controls.

RESULTS

The values of time domain variables were pre- and postoperatively lower in patients than in controls. A significant reduction was found in LF band after the implantation. Orthostatic hypotension was present in 45.8% of the patients preoperatively and 12.5% postoperatively. There was no correlation between DBS-related changes of motor function and corresponding neurophysiological measurements, but patients with more than 60% motor improvement had higher time domain parameters' values than the others.

CONCLUSIONS

STN-DBS offered no considerable impact on autonomic cardiovascular control.