Stimulation of the subthalamic nucleus in Parkinson's disease: a 5 year follow up

Five-year follow-up of 23 asymmetrical Parkinson's disease patients treated with unilateral subthalamic nucleus stimulation

In this study, 23 asymmetrical Parkinson's disease patients were treated with unilateral deep brain stimulation of the subthalamic nucleus and followed up for 5 years. At 5 years after stimulation treatment, Unified Parkinson's Disease Rating Scale II, III and axial symptom scores in the off-drug condition were significantly increased compared those at baseline. However, total Unified Parkinson's Disease Rating Scale II, III and axial symptom scores were significantly lower with stimulation-on compared with the synchronous stimulation-off state in off-drug condition, and the motor symptoms of contralateral side limbs were effectively controlled. Only low Hoehn-Yahr stage was correlated with good long-term postoperative improvement in motor symptoms. The mean levodopa-equivalent daily dose after stimulation treatment was significantly lower than that before treatment, but dyskinesias became worse. Our experimental findings indicate that unilateral deep brain stimulation of the subthalamic nucleus is an effective treatment for improving motor symptoms in well selected asymmetrical Parkinson's disease patients presenting no severe axial symptoms and dyskinesias.

Axial disability and deep brain stimulation in patients with Parkinson disease

Axial motor signs-including gait impairment, postural instability and postural abnormalities-are common and debilitating symptoms in patients with advanced Parkinson disease. Dopamine replacement therapy and physiotherapy provide, at best, partial relief from axial motor symptoms. In carefully selected candidates, deep brain stimulation (DBS) of the subthalamic nucleus or globus pallidus internus is an established treatment for 'appendicular' motor signs (limb tremor, bradykinesia and rigidity). However, the effects of DBS on axial signs are much less clear, presumably because motor control of axial and appendicular functions is mediated by different anatomical-functional pathways. Here, we discuss the successes and failures of DBS in managing axial motor signs. We systematically address a series of common clinical questions associated with the preoperative phase, during which patients presenting with prominent axial signs are considered for DBS implantation surgery, and the postoperative phase, in particular, the management of axial motor signs that newly develop as postoperative complications, either acutely or with a delay. We also address the possible merits of new targets-including the pedunculopontine nucleus area, zona incerta and substantia nigra pars reticulata-to specifically alleviate axial symptoms. Supported by a rapidly growing body of evidence, this practically oriented Review aims to support decision-making in the management of axial symptoms.

Axial disability and deep brain stimulation in patients with Parkinson disease

Axial motor signs-including gait impairment, postural instability and postural abnormalities-are common and debilitating symptoms in patients with advanced Parkinson disease. Dopamine replacement therapy and physiotherapy provide, at best, partial relief from axial motor symptoms. In carefully selected candidates, deep brain stimulation (DBS) of the subthalamic nucleus or globus pallidus internus is an established treatment for 'appendicular' motor signs (limb tremor, bradykinesia and rigidity). However, the effects of DBS on axial signs are much less clear, presumably because motor control of axial and appendicular functions is mediated by different anatomical-functional pathways. Here, we discuss the successes and failures of DBS in managing axial motor signs. We systematically address a series of common clinical questions associated with the preoperative phase, during which patients presenting with prominent axial signs are considered for DBS implantation surgery, and the postoperative phase, in particular, the management of axial motor signs that newly develop as postoperative complications, either acutely or with a delay. We also address the possible merits of new targets-including the pedunculopontine nucleus area, zona incerta and substantia nigra pars reticulata-to specifically alleviate axial symptoms. Supported by a rapidly growing body of evidence, this practically oriented Review aims to support decision-making in the management of axial symptoms.

Current perspectives on deep brain stimulation for severe neurological and psychiatric disorders

Deep brain stimulation (DBS) has become a well-accepted therapy to treat movement disorders, including Parkinson's disease, essential tremor, and dystonia. Long-term follow-up studies have demonstrated sustained improvement in motor symptoms and quality of life. DBS offers the opportunity to selectively modulate the targeted brain regions and related networks. Moreover, stimulation can be adjusted according to individual patients' demands, and stimulation is reversible. This has led to the introduction of DBS as a treatment for further neurological and psychiatric disorders and many clinical studies investigating the efficacy of stimulating various brain regions in order to alleviate severe neurological or psychiatric disorders including epilepsy, major depression, and obsessive-compulsive disorder. In this review, we provide an overview of accepted and experimental indications for DBS therapy and the corresponding anatomical targets.

Disentangling the Role of Cortico-Basal Ganglia Loops in Top-Down and Bottom-Up Visual Attention: An Investigation of Attention Deficits in Parkinson Disease

It is solidly established that top-down (goal-driven) and bottom-up (stimulus-driven) attention mechanisms depend on distributed cortical networks, including prefrontal and frontoparietal regions. On the other hand, it is less clear whether the BG also contribute to one or the other of these mechanisms, or to both. The current study was principally undertaken to clarify this issue. Parkinson disease (PD), a neurodegenerative disorder primarily affecting the BG, has proven to be an effective model for investigating the contribution of the BG to different brain functions; therefore, we set out to investigate deficits of top-down and bottom-up attention in a selected cohort of PD patients. With this objective in mind, we compared the performance on three computerized tasks of two groups of 12 parkinsonian patients (assessed without any treatment), one otherwise pharmacologically treated and the other also surgically treated, with that of a group of controls. The main behavioral tool for our study was an attentional capture task, which enabled us to tap the competition between top-down and bottom-up mechanisms of visual attention. This task was suitably combined with a choice RT and a simple RT task to isolate any specific deficit of attention from deficits in motor response selection and initiation. In the two groups of patients, we found an equivalent increase of attentional capture but also comparable delays in target selection in the absence of any salient distractor (reflecting impaired top-down mechanisms) and movement initiation compared with controls. In contrast, motor response selection processes appeared to be prolonged only in the operated patients. Our results confirm that the BG are involved in both motor and cognitive domains. Specifically, damage to the BG, as it occurs in PD, leads to a distinct deficit of top-down control of visual attention, and this can account, albeit indirectly, for the enhancement of attentional capture, reflecting weakened ability of top-down mechanisms to antagonize bottom-up control.

Lead-DBS: a toolbox for deep brain stimulation electrode localizations and visualizations

To determine placement of electrodes after deep brain stimulation (DBS) surgery, a novel toolbox that facilitates both reconstruction of the lead electrode trajectory and the contact placement is introduced. Using the toolbox, electrode placement can be reconstructed and visualized based on the electrode-induced artifacts on post-operative magnetic resonance (MR) or computed tomography (CT) images. Correct electrode placement is essential for efficacious treatment with DBS. Post-operative knowledge about the placement of DBS electrode contacts and trajectories is a promising tool for clinical evaluation of DBS effects and adverse effects. It may help clinicians in identifying the best stimulation contacts based on anatomical target areas and may even shorten test stimulation protocols in the future. Fifty patients that underwent DBS surgery were analyzed in this study. After normalizing the post-operative MR/CT volumes into standard Montreal Neurological Institute (MNI)-stereotactic space, electrode leads (n=104) were detected by a novel algorithm that iteratively thresholds each axial slice and isolates the centroids of the electrode artifacts within the MR/CT-images (MR only n=32, CT only n=10, MR and CT n=8). Two patients received four, the others received two quadripolar DBS leads bilaterally, summing up to a total of 120 lead localizations. In a second reconstruction step, electrode contacts along the lead trajectories were reconstructed by using templates of electrode tips that had been manually created beforehand. Reconstructions that were made by the algorithm were finally compared to manual surveys of contact localizations. The algorithm was able to robustly accomplish lead reconstructions in an automated manner in 98% of electrodes and contact reconstructions in 69% of electrodes. Using additional subsequent manual refinement of the reconstructed contact positions, 118 of 120 electrode lead and contact reconstructions could be localized using the toolbox. Taken together, the toolbox presented here allows for a precise and fast reconstruction of DBS contacts by proposing a semi-automated procedure. Reconstruction results can be directly exported to two- and three-dimensional views that show the relationship between DBS contacts and anatomical target regions. The toolbox is made available to the public in form of an open-source MATLAB repository.

Impulsive and compulsive behaviors in Parkinson's disease

BACKGROUND

Impulsive and compulsive behaviors (ICBs) are a heterogeneous group of conditions that may be caused by long-term dopaminergic replacement therapy (DRT) of Parkinson's disease (PD). The spectrum of ICBs includes dopamine dysregulation syndrome (DDS), punding, and impulse control disorders (ICDs).

CONTENTS

We made a detailed review regarding the epidemiology, pathology, clinical characteristics, risk factors, diagnosis as well as treatment of ICBs.

RESULTS

The prevalence of ICBs in PD patients is approximately 3-4% for DDS, 0.34-4.2% for punding, and 6-14% for ICDs, with higher prevalence in Western populations than in Asian. Those who take high dose of levodopa are more prone to have DDS, whereas, ICDs are markedly associated with dopamine agonists. Different subtypes of ICBs share many risk factors such as male gender, higher levodopa equivalent daily dose, younger age at PD onset, history of alcoholism, impulsive, or novelty-seeking personality. The Questionnaire for Impulsive-Compulsive Disorder in Parkinson's Disease-Rating Scale seems to be a rather efficacious instrument to obtain relevant information from patients and caregivers. Treatment of ICBs is still a great challenge for clinicians. Readjustment of DRT remains the primary method. Atypical antipsychotics, antidepressants, amantadine, and psychosocial interventions are also prescribed in controlling episodes of psychosis caused by compulsive DRT, but attention should be drawn to balance ICBs symptoms and motor disorders. Moreover, deep brain stimulation of the subthalamic nucleus might be a potential method in controlling ICBs.

CONCLUSION

The exact pathophysiological mechanisms of ICBs in PD remains poorly understood. Further researches are needed not only to study the pathogenesis, prevalence, features, and risk factors of ICBs, but to find efficacious therapy for patients with these devastating consequences.

Subthalamic nucleus high-frequency stimulation for advanced Parkinson's disease: motor and neuropsychological outcome after 10 years

BACKGROUND

Since the introduction of subthalamic nucleus deep brain stimulation (STN DBS), many clinical studies have shown that this therapy is safe and effective in the short and medium term. Only little is known about long-term results.

OBJECTIVES

To provide an analysis of motor and cognitive outcome 10 years after STN DBS.

METHODS

In this observational cohort study, we report on the motor and cognitive outcome in a cohort of 26 Parkinson's disease patients who were prospectively followed up for 10 years after STN DBS surgery.

RESULTS

In the early post-operative phase, improvement in the Unified Parkinson's Disease Rating Scale (UPDRS) III (10.6, p < 0.01) and IV (2.5, p < 0.01) was seen as well as a 32% reduction in levodopa equivalent dose (p < 0.01). After 5 years, a worsening of the motor performance was observed. The worsening of motor performance was mainly due to a deterioration in bradykinesia (12.4 ± 4.6, p < 0.05) and axial symptoms (6.9 ± 2.8, p < 0.01). Memory function seemed to improve in the short term, but there was a significant decline between 1 and 5 years after surgery (p < 0.01). Mood remained relatively stable during follow-up, and one third of the patients showed impulsive behaviour after surgery.

CONCLUSIONS

The motor performance of patients showed deterioration over time, due to an increase in bradykinesia and axial symptoms.

[Deep brain stimulation for Parkinson's disease: timing and patient selection]

Deep brain stimulation (DBS) is an effective and evidence-based treatment option for Parkinson's disease. Studies have shown that DBS has good and long-term effects on motor function and quality of life for patients in an advanced stage of the disease and that it is more effective than medical therapy alone. Moreover, a favorable effect of DBS could also be detected at an earlier stage of the disease. On the other hand, possible risks and side effects of the procedure need to be taken into consideration. These can manifest as procedure-related complications, such as bleeding and infections in addition to stimulation-associated phenomena, such as neuropsychiatric disorders and motor side effects. Despite the good effects of DBS important issues still need to be addressed which will be discussed in this article considering the results of several new randomized and controlled clinical studies. For patients with Parkinson's disease with early fluctuations and dyskinesia, DBS has been found to be superior to the best pharmaceutical treatment; therefore, DBS can be considered as a treatment option in the earlier course of the disease. The diagnostic evaluation and the exclusion of contraindications are crucial for patient selection. The choice of the target should be based on the individual symptoms in patients although the subthalamic nucleus (STN) can be considered the standard target. In every case an individual assessment of chances and risks must be conducted and realistic goals and reasonable expectations must be defined.

Subthalamic nucleus deep brain stimulation for Parkinson's disease: evidence for effectiveness and limitations from 12 years' experience

OBJECTIVE

To present the result and experience of subthalamic nucleus deep brain stimulation for Parkinson's disease.

DESIGN

Case series.

SETTING

Prince of Wales Hospital, Hong Kong.

PATIENTS

A cohort of patients with Parkinson's disease received subthalamic nucleus deep brain stimulation from September 1998 to January 2010. Patient assessment data before and after the operation were collected prospectively.

RESULTS

Forty-one patients (21 male and 20 female) with Parkinson's disease underwent bilateral subthalamic nucleus deep brain stimulation and were followed up for a median interval of 12 months. For the whole group, the mean improvements of Unified Parkinson's Disease Rating Scale (UPDRS) parts II and III were 32.5% and 31.5%, respectively (P<0.001). Throughout the years, a multidisciplinary team was gradually built. The deep brain stimulation protocol evolved and was substantiated by updated patient selection criteria and outcome assessment, integrated imaging and neurophysiological targeting, refinement of surgical technique as well as the accumulation of experience in deep brain stimulation programming. Most of the structural improvement occurred before mid-2005. Patients receiving the operation before June 2005 (19 cases) and after (22 cases) were compared; the improvements in UPDRS part III were 13.2% and 55.2%, respectively (P<0.001). There were three operative complications (one lead migration, one cerebral haematoma, and one infection) in the group operated on before 2005. There was no operative mortality.

CONCLUSIONS

The functional state of Parkinson's disease patients with motor disabilities refractory to best medical treatment improved significantly after subthalamic nucleus deep brain stimulation. A dedicated multidisciplinary team building, refined protocol for patient selection and assessment, improvement of targeting methods, meticulous surgical technique, and experience in programming are the key factors contributing to the improved outcome.

Controlled general anaesthesia for subthalamic nucleus stimulation in Parkinson's disease

OBJECTIVE

To report the short-term (1 year) and long-term (5 years) outcome of patients with Parkinson's disease (PD) with subthalamic nucleus (STN) stimulation operated upon under controlled general anaesthesia (GA).

METHODS

213 consecutive patients with PD were included between January 2000 and March 2009 and operated upon under a particular type of GA with close control of the level of sedation allowing intraoperative recordings. 188 patients were assessed 1 year postoperatively. 65 patients also completed the long-term observation period and were evaluated 5 years postoperatively.

RESULTS

The Unified PD Rating Scale III score in the 'Off drug--On stim' condition was improved at 1 year and 5 years by 61% and 37%, respectively, (p<0.001). Motor complications decreased at short-term and long-term by 68% and 65%, respectively, for dyskinesia and by 52% and 48%, respectively, for fluctuations, (p<0.001). Dopaminergic treatment could also be reduced at short-term and long-term by 46% and 49%, respectively (p<0.001). There was no significant modification of mood and cognition assessments (Mattis scale and Beck depression inventory) at 1 year and 5 years. Concerning the main adverse events related to the surgery, we report four haematomas (1.9%) with two deaths (0.9%), eight cases of transient confusion (3.7%) and no epileptic seizure.

CONCLUSIONS

Our results confirm that STN stimulation performed under controlled GA is efficient and has similar short-term and long-term motor effects than intervention under local anaesthesia. Furthermore, this specific procedure is not associated with more adverse events. The success of such an intervention requires strict anaesthetic monitoring and accurate STN identification.

Medical therapy and subthalamic deep brain stimulation in advanced Parkinson's disease: a different long-term outcome?

OBJECTIVES

Few clinical trials reported the comparative short-term efficacy of subthalamic nucleus deep brain stimulation (STN-DBS) versus medical therapy in advanced Parkinson's disease (PD). However, the comparative efficacy, safety and the potential disease-modifying effect of these treatments have not been investigated over a longer follow-up period.

METHODS

In this study, we organised a 'retrospective control group' to compare medical and surgical therapies over a long-term period. We assessed a group of PD patients suitable for STN-DBS but successively treated with medical therapies for reasons not related to PD, and a group of similar consecutive STN-DBS patients. We thus obtained two groups comparable at baseline, which were re-evaluated after an average follow-up of 6 years (range 4-11).

RESULTS

Patients treated with STN-DBS showed a long-lasting superior clinical efficacy on motor fluctuations, with a significant reduction in the average percentage of the waking day spent in 'OFF' and in the duration and disability of dyskinesia. Moreover, operated patients showed a better outcome in the activities of daily living in 'Medication-OFF' condition. On the other hand, a similar progression of motor score and cognitive/behavioural alterations was observed between the two groups, apart from phonemic verbal fluency, which significantly worsened in STN-DBS patients.

CONCLUSIONS

To our knowledge, this is the first long-term comparison between medical and surgical therapies; a superior efficacy of STN-DBS was observed on motor disability, while no significant differences were observed in the progression of motor symptoms and, apart from phonemic verbal fluency, of neuropsychological alterations.

Surgical treatment of dyskinesia in Parkinson's disease

One of the main indications for stereotactic surgery in Parkinson's disease (PD) is the control of levodopa-induced dyskinesia. This can be achieved by pallidotomy and globus pallidus internus (GPi) deep brain stimulation (DBS) or by subthalamotomy and subthalamic nucleus (STN) DBS, which usually allow for a cut down in the dosage of levodopa. DBS has assumed a pivotal role in stereotactic surgical treatment of PD and, in fact, ablative procedures are currently considered surrogates, particularly when bilateral procedures are required, as DBS does not produce a brain lesion and the stimulator can be programed to induce better therapeutic effects while minimizing adverse effects. Interventions in either the STN and the GPi seem to be similar in controlling most of the other motor aspects of PD, nonetheless, GPi surgery seems to induce a more particular and direct effect on dyskinesia, while the anti-dyskinetic effect of STN interventions is mostly dependent on a reduction of dopaminergic drug dosages. Hence, the si ne qua non-condition for a reduction of dyskinesia when STN interventions are intended is their ability to allow for a reduction of levodopa dosage. Pallidal surgery is indicated when dyskinesia is a dose-limiting factor for maintaining or introducing higher adequate levels of dopaminergic therapy. Also medications used for the treatment of PD may be useful for the improvement of several non-motor aspects of the disease, including sleep, psychiatric, and cognitive domains, therefore, dose reduction of medication withdrawal are not always a fruitful objective.

Criteria for deep-brain stimulation in Parkinson’s disease: review and analysis

Deep-brain stimulation is currently the most effective surgical treatment for advanced Parkinson's disease. The relevant targets to date are the subthalamic nucleus and the globus pallidus internus, although the thalamus (ventralis intermedius nucleus) is preferred in tremor-dominant, aged Parkinson's disease patients. Long-term benefit in cardinal parkinsonian signs, motor fluctuations and dyskinesia has been reported in 5-year follow-up studies of subthalamic nucleus deep-brain stimulation. However, some psychiatric consequences have raised important issues and emphasized the need for an experienced deep-brain stimulation surgical team. This team should be multidisciplinary and involve movement disorder neurologists, neurosurgeons, neuropsychologists and psychiatrists. The recent observation that deep-brain stimulation of the pedunculopontine nucleus improves axial signs, possibly even in those less responsive to levodopa, brings new hope to the management of advanced Parkinson's disease.

Deep brain stimulation: indications and evidence

Deep brain stimulation is a minimally invasive targeted neurosurgical intervention that enables structures deep in the brain to be stimulated electrically by an implanted pacemaker. It has become the treatment of choice for Parkinson's disease, refractory to, or complicated by, drug therapy. Its efficacy has been demonstrated robustly by randomized, controlled clinical trials, with multiple novel brain targets having been discovered in the last 20 years. Multifarious clinical indications for deep brain stimulation now exist, including dystonia and tremor in movement disorders; depression, obsessive-compulsive disorder and Tourette's syndrome in psychiatry; epilepsy, cluster headache and chronic pain, including pain from stroke, amputation, trigeminal neuralgia and multiple sclerosis. Current research argues for novel indications, including hypertension and orthostatic hypotension. The development, principles, indications and effectiveness of the technique are reviewed here. While deep brain stimulation is a standard and widely accepted treatment for Parkinson's disease after 20 years of experience, in chronic pain it remains restricted to a handful of experienced, specialist centers willing to publish outcomes despite its use for over 50 years. Reasons are reviewed and novel approaches to appraising clinical evidence in functional neurosurgery are suggested.

Effects of deep brain stimulation of the subthalamic nucleus on inhibitory and executive control over prepotent responses in Parkinson's disease

Inhibition of inappropriate, habitual or prepotent responses is an essential component of executive control and a cornerstone of self-control. Via the hyperdirect pathway, the subthalamic nucleus (STN) receives inputs from frontal areas involved in inhibition and executive control. Evidence is reviewed from our own work and the literature suggesting that in Parkinson's disease (PD), deep brain stimulation (DBS) of the STN has an impact on executive control during attention-demanding tasks or in situations of conflict when habitual or prepotent responses have to be inhibited. These results support a role for the STN in an inter-related set of processes: switching from automatic to controlled processing, inhibitory and executive control, adjusting response thresholds and influencing speed-accuracy trade-offs. Such STN DBS-induced deficits in inhibitory and executive control may contribute to some of the psychiatric problems experienced by a proportion of operated cases after STN DBS surgery in PD. However, as no direct evidence for such a link is currently available, there is a need to provide direct evidence for such a link between STN DBS-induced deficits in inhibitory and executive control and post-surgical psychiatric complications experienced by operated patients.

Linking reward processing to behavioral output: motor and motivational integration in the primate subthalamic nucleus

The expectation and detection of motivationally relevant events is a major determinant of goal-directed behavior and there is a strong interest in the contribution of basal ganglia in the integration of motivational processes into behavioral output. Recent research has focused on the role of the subthalamic nucleus (STN) in the motivational control of action, but it remains to be determined how information about reward is encoded in this nucleus. We recorded the activity of single neurons in the STN of two behaving monkeys to examine whether activity was influenced by the delivery of reward in an instrumental task, a Pavlovian stimulus-reward association, or outside of a task context. We confirmed preliminary findings indicating that STN neurons were sensitive not only to rewards obtained during task performance, but also to the expectation of reward when its delivery was delayed in time. Most of the modulations at the onset of reaching movement were combined with modulations following reward delivery, suggesting the convergence of signals related to the animal's movement and its outcome in the same neurons. Some neurons were also influenced by the visuomotor contingencies of the task, i.e., target location and/or movement direction. In addition, modulations were observed under conditions where reward delivery was not contingent on an instrumental response, even in the absence of a reward predictive cue. Taken as a whole, these results demonstrate a potential contribution of the STN to motivational control of behavior in the non-human primate, although problems in distinguishing neuronal signals related to reward from those related to motor behavior should be considered. Characterizing the specificity of reward processing in the STN remains challenging and could have important implications for understanding the influence of this key component of basal ganglia circuitry on emotional and motivated behaviors under normal and pathological conditions.

Facilitative effects of bi-hemispheric tDCS in cognitive deficits of Parkinson disease patients

Parkinson's disease (PD) is a progressive neurodegenerative disorder, primarily characterized by motor symptoms such as tremor, rigidity, bradykinesia, stiffness, slowness and impaired equilibrium. Although the motor symptoms have been the focus in PD, slight cognitive deficits are commonly found in non-demented and non-depressed PD patients, even in early stages of the disease, which have been linked to the subsequent development of pathological dementia. Thus, strongly reducing the quality of life (QoL). Both levodopa therapy and deep brain stimulation (DBS) have yield controversial results concerning the cognitive symptoms amelioration in PD patients. That does not seems to be the case with transcranial direct current stimulation (tDCS), although better stimulation parameters are needed. Therefore we hypothesize that simultaneously delivering cathodal tDCS (or ctDCS), over the right prefrontal cortex delivered with anodal tDCS (or atDCS) to left prefrontal cortex could be potentially beneficial for PD patients, either by mechanisms of homeostatic plasticity and by increases in the extracellular dopamine levels over the striatum.

Subthalamic neurostimulation for Parkinson's disease with early fluctuations: balancing the risks and benefits

Electrical stimulation of the subthalamic nucleus is an established treatment for patients with advanced Parkinson's disease with pharmacologically unresponsive fluctuations. Compared with pharmacological treatment, subthalamic neurostimulation significantly improves motor symptoms, particularly during the phases of poor response to drug treatment, and reduces the severity of dyskinesias. Importantly, it also significantly improves quality of life and other integral measures of disease severity. The treatment response can last for more than 10 years, although there is no evidence that levodopa-resistant symptoms are delayed by subthalamic neurostimulation. At present, the mean disease duration for patients at the time of implantation is 12 years. In a recent study (EARLYSTIM) in patients with a disease duration of 7·5 years and fluctuations for 1·5 years, similar improvements in clinical outcomes were reported. These findings suggest that neurostimulation of the subthalamic nucleus could be used earlier in the disease course for carefully selected patients if the benefits of the treatment are weighed against the surgical risks and the lifelong need for specialised care by an experienced team. As mobility is consistently improved during the times with poor mobility by reducing fluctuations and delaying levodopa-sensitive complications, we propose that this treatment changes the disease course.

Neurosurgery in Parkinson's disease: Social adjustment, quality of life and coping strategies

Subthalamic nucleus deep brain stimulation has become a standard neurosurgical therapy for advanced Parkinson's disease. Subthalamic nucleus deep brain stimulation can dramatically improve the motor symptoms of carefully selected patients with this disease. Surprisingly, some specific dimensions of quality of life, “psychological” aspects and social adjustment do not always improve, and they could sometimes be even worse. Patients and their families should fully understand that subthalamic nucleus deep brain stimulation can alter the motor status and time is needed to readapt to their new postoperative state and lifestyles. This paper reviews the literatures regarding effects of bilateral subthalamic nucleus deep brain stimulation on social adjustment, quality of life and coping strategies in patients with Parkinson's disease. The findings may help to understand the psychosocial maladjustment and poor improvement in quality of life in some Parkinson's disease patients.

60-Hz frequency effect on gait in Parkinson's disease with subthalamic nucleus deep brain stimulation

OBJECTIVE

Gait dysfunction is common in advancing Parkinson's disease and has a disappointing response to dopamine replacement and subthalamic nucleus deep brain stimulation programming parameters. Low-frequency stimulation, less than 130 Hz in combination with increased voltage, has been shown to decrease freezing episodes and number of steps with little impact on overall performance measured by the Unified Parkinson's Disease Rating Scale. This was in the setting of delivering the same total energy, which required both a change in voltage and frequency. We wanted to determine if the benefit came from low frequency alone.

MATERIALS AND METHODS

We enrolled 20 Parkinson's patients who were at least three months in postbilateral subthalamic deep brain stimulation and reported gait changes. Subjects held their Parkinson's medications overnight, and following a baseline evaluation, they were randomly assigned to both 60 and 130 Hz stimulation in a blinded fashion with all other parameters held constant. Each subject was set at each frequency twice during the study, with a 60-min stimulation interval prior to each gait evaluation.

RESULTS

There was no significant difference between the two frequencies, with the primary outcome measure of stride length. Two of the 20 patients reported a significant subjective improvement in their gait with no statistical difference in their outcomes. There also was less tremor control at 60 Hz.

CONCLUSION

We were unable to demonstrate improved gait with lower frequency stimulation as suggested by prior studies. This may have been because of the decreased energy delivered from the lower frequency and unchanged voltage.

Factors related to outcomes of subthalamic deep brain stimulation in Parkinson's disease

OBJECTIVE

Subthalamic nucleus (STN) deep brain stimulation (DBS) is an effective treatment of choice for patients with advanced idiopathic Parkinson's disease (PD) who have motor complication with medication. The objectives of this study are to analyze long-term follow-up data of STN DBS cases and to identify the factors related to outcomes.

METHODS

Fifty-two PD patients who underwent STN DBS were followed-up for more than 3 years. The Unified Parkinsons Disease Rating Scale (UPDRS) and other clinical profiles were assessed preoperatively and during follow-up. A linear regression model was used to analyze whether factors predict the results of STN DBS. We divided the study individuals into subgroups according to several factors and compared subgroups.

RESULTS

Preoperative activity of daily living (ADL) and the magnitude of preoperative levodopa response were shown to predict the improvement in UPDRS part II without medication, and preoperative ADL and levodopa equivalent dose (LED) were shown to predict the improvement in UPDRS part II with medication. In UPDRS part III with medication, the magnitude of preoperative levodopa response was a predicting factor.

CONCLUSION

The intensity of preoperative levodopa response was a strong factor for motor outcome. And preoperative ADL and LED were strong factors for ADL improvement. More vigorous studies should be conducted to elucidate how levodopa-induced motor complications are ameliorated after STN DBS.

Summary of the recommendations of the EFNS/MDS-ES review on therapeutic management of Parkinson's disease

OBJECTIVE

To summarize the 2010 EFNS/MDS-ES evidence-based treatment recommendations for the management of Parkinson's disease (PD). This summary includes the treatment recommendations for early and late PD.

METHODS

For the 2010 publication, a literature search was undertaken for articles published up to September 2009. For this summary, an additional literature search was undertaken up to December 2010. Classification of scientific evidence and the rating of recommendations were made according to the EFNS guidance. In cases where there was insufficient scientific evidence, a consensus statement ('good practice point') is made.

RESULTS AND CONCLUSIONS

For each clinical indication, a list of therapeutic interventions is provided, including classification of evidence.

Initial cognitive dip after subthalamic deep brain stimulation in Parkinson disease

Although many studies have shown no significant change in global cognitive function after subthalamic brain stimulation (STN DBS) in patients with Parkinson disease (PD) and have concluded that STN DBS is generally safe from a cognitive standpoint, some studies have reported a decline in global cognitive function after STN DBS. Interestingly, in some studies, the decline in cognitive function appears to be greater during the initial short period after surgery (within 6 or 12 months after surgery) than the decline thereafter. To this end, we examined whether the rate of change in global cognitive function during the initial 6 months after STN DBS was different from the mean 6-month change that occurred between 6 and 36 months after surgery. Thirty-six PD patients who underwent bilateral STN DBS and were followed for more than 3 years were included. Change in Mini-Mental Status Examination (MMSE) score during the first 6 months after surgery was compared with the 6-month MMSE score change between 6 and 36 months after surgery. Mean MMSE change during the first 6 months after surgery was significantly greater than the mean 6-month MMSE change between 6 to 36 months after surgery. The levodopa equivalent daily dose at baseline and the score for Stroop Color-word test at baseline were significantly associated with the decline in MMSE score during the first 6 months after surgery. Our result showed that decline in global cognitive function was faster in the first 6 months after surgery, compared with that after 6 months.

Surgical treatment of Parkinson disease: past, present, and future

Advances in functional neurosurgery have expanded the treatment of Parkinson disease (PD) to targeted electrical stimulation of specific nodes in the basal ganglia circuitry. Deep brain stimulation (DBS), applied to selected patients and difficult-to-manage motor fluctuations, yields substantial reductions in off time and dyskinesia. Emerging concepts in DBS include examination of new targets, such as the potential efficacy of pedunculopontine nucleus stimulation for treatment of freezing and falls, the use of pathologic oscillations in the beta band to construct an adaptive "closed-loop" DBS, and new technologies, including segmented electrodes to steer current toward specific neural populations.

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.

Cost analysis of the treatments for patients with advanced Parkinson's disease: SCOPE study

OBJECTIVE

To perform a comparative long-term analysis of the associated healthcare costs for the therapeutic options in advanced Parkinson's Disease (PD): deep brain stimulation (DBS), continuous duodenal levodopa-carbidopa infusion (CDLCI), and continuous subcutaneous apomorphine infusion (CSAI).

METHODS

Resource use associated with the pre-treatment period, procedure, and follow-up was assessed for the three therapies from the perspective of the Spanish national healthcare system. Resources consumption was measured with a Healthcare Resources Questionnaire (at nine advanced PD centres). Unit costs (Euro-Spain 2010) were applied to measure resource use to obtain the average total cost for each therapy over 5 years.

RESULTS

Mean cumulative 5-year cost per patient was significantly lower with DBS (€88,014) vs CSAI (€141,393) and CDLCI (€233,986) (p < 0.0001). DBS was associated with the lowest cumulative costs from year 2, with a yearly average cost of €17,603 vs €46,797 for CDLCI (p = 0.001) and €28,279 for CSAI (p = 0.008). For every patient treated annually with CDLCI, two could be treated with DBS (or €29,194 could be saved) and for every patient treated with CSAI, €10,676 could be saved with DBS. The initial DBS investment (32.2% of the total 5-year costs) was offset by decreases in anti-Parkinsonian drugs and follow-up costs. CDLCI and CSAI required constant drug use (i.e., levodopa and carbidopa for CDLCI, apomorphine for CSAI), representing ∼95% of their total 5-year cost.

LIMITATIONS

All costs were based on a questionnaire, not on actual clinical data. The study is not a cost-effectiveness analysis as there is a lack of comparable outcomes data. An expert panel was used due to the complexity and variability in the treatment of advanced PD. The sample size was relatively small.

CONCLUSIONS

Overall, DBS requires less use of health resources than CDLCI or CSAI in advanced PD patients, mostly pharmacological. The initial DBS investment was offset at year 2 by reductions in the ongoing consumption of anti-Parkinsonian medication. For every patient treated annually with CDLCI or CSAI, substantial cost savings could be made with DBS.

Clinical outcome of deep brain stimulation for Parkinson's disease

Deep brain stimulation is one of the most effective treatments of Parkinson's disease (PD). This report summarizes the state of the art as at January 2013. Stimulation of the subthalamic nucleus is the most commonly used approach. It improves the core motor symptoms better than medication in patients with advanced disease. It also improves the majority of nonmotor symptoms, such as mood, impulse control disorders, sleep, and some autonomic dysfunctions. Quality of life (QoL) is improved significantly more than with medication. Long-term data show that the treatment is effective for up to 10 years, but the late appearance of l-dopa-resistant symptoms is seemingly not influenced. Internal globus pallidus (GPi) stimulation is less well studied but seems to have similar short-term efficacy. Importantly l-dopa use cannot be reduced with GPi DBS, which is a major disadvantage for patients suffering from medication side-effects, although gait may be influenced more positively. Although short-term QoL improvement seems to be similar to that for subthalamic nucleus (STN) DBS - gait and speech may be better improved - long-term data are rare for GPi DBS. Thalamic stimulation in the ventral intermediate nucleus (VIM) is applied only in tremor-dominant elderly patients. The treatment improves the dopa-sensitive symptoms and effectively reduces fluctuations leading to an overall QoL improvement. Although most of the controlled studies have been on advanced PD, the recently published EARLYSTIM study suggests that even patients with a very short duration of their fluctuations and dyskinesia are doing significantly better with neurostimulation in terms of QoL and all major motor outcome parameters.

Amantadine improves gait in PD patients with STN stimulation

In advanced Parkinson's disease (PD), axial symptoms such as speech, gait, and balance impairment often become levodopa-unresponsive and they are difficult to manage, even in patients with subthalamic nucleus deep brain stimulation (STN-DBS). We anecdotally observed that oral administration of amantadine was very effective in treating both residual and stimulation-induced axial symptoms after bilateral STN-DBS in one PD patient. Therefore, we conducted a prospective multicenter observational study to evaluate the effects of amantadine on speech, gait and balance in PD patients with STN-DBS and incomplete axial benefit. Primary outcomes were changes in speech (UPDRS III, item 18), gait (item 29) and postural stability (item 30) with amantadine treatment compared to baseline. Secondary outcome was the patients' subjective scoring of axial symptoms with amantadine compared to baseline. Forty-six PD patients with STN-DBS were enrolled in the study and followed for 10.35 ± 8.21 months (median: 9.00; range: 1-31). The mean daily dose of amantadine was 273.44 ± 47.49 mg. Gait scores significantly improved (from 1.51 ± 0.89 to 1.11 ± 0.92, P = 0.015) with amantadine treatment, whereas postural stability and speech scores were similar before and after treatment. Thirty-five (76.1%) patients reported subjective improvement in speech, gait or balance with amantadine, whereas thirty (65.2%) patients reported improvement in gait and balance. In conclusion, our data suggest that amantadine may have new beneficial effects on axial symptoms in PD patients with STN-DBS.

Clinical outcomes of PD patients having bilateral STN DBS using high-field interventional MR-imaging for lead placement

OBJECTIVE

Recently, an iMRI-guided technique for implanting DBS electrodes without MER was developed at our center. Here we report the clinical outcomes of PD patients undergoing STN DBS surgery using this surgical approach.

METHODS

Consecutive PD patients undergoing bilateral STN DBS using this method were prospectively studied. Severity of PD was determined using the UPDRS scores, Hoehn and Yahr staging score, stand-sit-walk testing, and the dyskinesia rating scale. The primary outcome measure was the change in UPDRS III off medication score at 6 months. DBS stimulation parameters, adverse events, levodopa equivalent daily dose (LEDD), and DBS lead locations were also recorded. Seventeen advanced PD patients (9M/8F) were enrolled from 2007 to 2009.

RESULTS

The mean UPDRS III off medication score improved from 44.5 to 22.5 (49.4%) at 6 months (p=0.001). Other secondary outcome measures (UPDRS II, III on medication, and IV) significantly improved as well (p<0.01). LEDD decreased by an average of 24.7% (p=0.003). Average stimulation parameters were: 2.9V, 66.4μs, 154Hz.

CONCLUSION

This pilot study demonstrates that STN DBS leads placed using the iMRI-guided method results in significantly improved outcomes in PD symptoms, and these outcomes are similar to what has been reported using traditional frame-based, MER-guided stereotactic methods.

A comparison of LEDD and motor scores following STN-DBS treatment in patient with young onset vs. late onset Parkinson's disease

INTRODUCTION

We compared the role of subthalamic nucleus deep brain stimulation (STN-DBS) in the management of medically refractory idiopathic Parkinson's disease in patients with relatively young onset (<40 years of age) Parkinson's disease (YOPD) and patients with relatively late onset Parkinson's disease (≥ 56 years of age, rLOPD).

METHODS

A total of 33 patients with YOPD (18 patients, median age 32.5 years, range, 20-40 years) and rLOPD (15 patients, median age 58.0 years, range, 56.0-67.0 years) underwent STN-DBS between May 2000 and May 2008. We divided the patients into YOPD and rLOPD as the age of disease onset. The median follow-up period was 43 months (range, 12-95 months). We assessed Hoehn and Yahr stages, activities of daily living, and Unified Parkinson's Disease Rating Scale (UPDRS) motor scales (III) for all patients preoperatively and at six months postoperatively. We measured levodopa equivalent doses (LEDD) and stimulation parameters preoperatively, six months postoperatively, and 12 months postoperatively.

RESULTS

There were no significant differences in UPDRS motor scales between two groups at preoperative and six-month postoperative drug off/stim on, but UPDRS III was lower in rLOPD at six-month postoperative drug on/stim on state. A significant difference was noted in the improvement of UPDRS III between two groups for preoperative drug off and drug on conditions, but no difference was seen between two groups in a comparison of drug off/stim on vs. drug on/stim on conditions. Stimulation parameters and postoperative LEDD were not different between the two groups. Preoperative dyskinesia was more common in YOPD patients and, psychotic problems were more common in rLOPD patients.

CONCLUSIONS

Patients with YOPD and rLOPD exhibited comparable UPDRS motor scores and LEDD six months postoperatively. Levodopa could be prescribed at optimum doses following STN-DBS in patients with YOPD as abnormal movements are better controlled following STN-DBS implantation. Stimulation parameters were not different between the two groups. Our results suggest the age of onset does not influence response to STN-DBS Parkinson's disease patients.

Brain stimulation methods to treat tobacco addiction

BACKGROUND

Tobacco smoking is the leading cause of preventable deaths worldwide, but many smokers are simply unable to quit. Psychosocial and pharmaceutical treatments have shown modest results on smoking cessation rates, but there is an urgent need to develop treatments with greater efficacy. Brain stimulation methods are gaining increasing interest as possible addiction therapeutics.

OBJECTIVES

The purpose of this paper is to review the studies that have evaluated brain stimulation techniques on tobacco addiction, and discuss future directions for research in this novel area of addiction interventions.

METHODS

Electronic and manual literature searches identified fifteen studies that administered repetitive transcranial magnetic stimulation (rTMS), cranial electrostimulation (CES), transcranial direct current stimulation (tDCS) or deep brain stimulation (DBS).

RESULTS

rTMS was found to be the most well studied method with respect to tobacco addiction. Results indicate that rTMS and tDCS targeted to the dorsolateral prefrontal cortex (DLPFC) were the most efficacious in reducing tobacco cravings, an effect that may be mediated through the brain reward system involved in tobacco addiction. While rTMS was shown to reduce consumption of cigarettes, as yet no brain stimulation technique has been shown to significantly increase abstinence rates. It is possible that the therapeutic effects of rTMS and tDCS may be improved by optimization of stimulation parameters and increasing the duration of treatment.

CONCLUSION

Although further studies are needed to confirm the ability of brain stimulation methods to treat tobacco addiction, this review indicates that rTMS and tDCS both represent potentially novel treatment modalities.

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.

Randomized trial of deep brain stimulation for Parkinson disease: thirty-six-month outcomes

OBJECTIVES

Our objective was to compare long-term outcomes of deep brain stimulation (DBS) of the globus pallidus interna (GPi) and subthalamic nucleus (STN) for patients with Parkinson disease (PD) in a multicenter randomized controlled trial.

METHODS

Patients randomly assigned to GPi (n = 89) or STN DBS (n = 70) were followed for 36 months. The primary outcome was motor function on stimulation/off medication using the Unified Parkinson's Disease Rating Scale motor subscale. Secondary outcomes included quality of life and neurocognitive function.

RESULTS

Motor function improved between baseline and 36 months for GPi (41.1 to 27.1; 95% confidence interval [CI] -16.4 to -10.8; p < 0.001) and STN (42.5 to 29.7; 95% CI -15.8 to -9.4; p < 0.001); improvements were similar between targets and stable over time (p = 0.59). Health-related quality of life improved at 6 months on all subscales (all p values significant), but improvement diminished over time. Mattis Dementia Rating Scale scores declined faster for STN than GPi patients (p = 0.01); other neurocognitive measures showed gradual decline overall.

CONCLUSIONS

The beneficial effect of DBS on motor function was stable and comparable by target over 36 months. Slight declines in quality of life following initial gains and gradual decline in neurocognitive function likely reflect underlying disease progression and highlight the importance of nonmotor symptoms in determining quality of life.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that improvement of motor symptoms of PD by DBS remains stable over 3 years and does not differ by surgical target. Neurology® 2012;79:55-65.