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

Update on surgery for Parkinson's disease

PURPOSE OF REVIEW

The clinical effectiveness and limitations of subthalamic nucleus deep brain stimulation for Parkinson's disease are summarized and recent developments concerning alternative brain targets for deep brain stimulation or restorative surgical therapies are discussed.

RECENT FINDINGS

In a controlled study subthalamic nucleus deep brain stimulation was superior to best medical management in improving quality of life of patients with advanced Parkinson's disease. The benefits of the procedure on levodopa-sensitive motor symptoms are sustained for up to 5 years, but it does not halt disease progression. Cognitive decline and worsening of axial motor symptoms may limit the overall benefit. Age at the time of surgery is an important factor for long-term stability and safety. Psychosocial aspects of Parkinson's disease can profoundly impact on the ability of a patient to reintegrate after surgery and have to be considered in patient selection. Stimulation of the pedunculopontine nucleus may have an additive effect on postural and gait symptoms, which do not respond to levodopa or subthalamic nucleus deep brain stimulation.

SUMMARY

Deep brain stimulation is emerging from an empirical to an evidence based therapy. The safety and efficacy of the procedure may legitimize surgery at a younger age before social maladjustment prevents reintegration of the patient into a normal life.

Modeling parkinsonian circuitry and the DBS electrode. I. Biophysical background and software

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) for Parkinson's disease (PD) has become routine over the past decade, utilizing microelectrode recordings to ensure accurate placement of the stimulating electrodes. The clinical benefits of STN DBS for PD are well documented, but the mechanisms by which DBS achieves these results remain elusive. We have created a closed-form mathematical function of the potential field generated by a typical 4-contact DBS electrode and inserted this function into a computational model designed to simulate individual neurons and neural circuitry of significant portions of the basal ganglia. We present the mathematical function representing the potential field itself and the basis for the neural circuitry modeling in this paper.

Functional balance performance in patients with Parkinson's disease after long-term treatment with subthalamic nucleus high-frequency stimulation

The aim was to investigate if functional balance performance in patients with Parkinson's disease (PD) was affected by long-term (3 years) treatment with bilateral subthalamic nucleus (STN) high-frequency stimulation. Thirty-five patients were consecutively included, and 28 patients completed the study (mean age 62 years, SD 6.5). The Berg Balance Scale (BBS) was assessed preoperatively and 1 and 3 years postoperatively (with and without anti-PD medication and with the STN stimulation turned OFF or ON). Although the balance performance of patients with PD decreased over time, the functional balance performance was still positively affected by STN stimulation alone 3 years after surgery.

Long-term outcome of 50 consecutive Parkinson's disease patients treated with subthalamic deep brain stimulation

OBJECTIVE

To describe the long-term outcome in 50 consecutive advanced Parkinson's disease (PD) patients treated with subthalamic nucleus deep brain stimulation (STN-DBS).

METHOD

Assessments were carried out at baseline, 6 months, 2 years, and 5 years postoperatively.

RESULTS

Compared to baseline scores without medication, we found a highly significant improvement of UPDRS III with stimulation, maintained at 5 years (p<0.001). This improvement, however, tended to diminish over time. Dyskinesia and off periods were also improved (p<0.0001 for both). Seventeen patients died during follow-up, who tended to be older at surgery (p<0.01).

CONCLUSIONS

STN-DBS is an effective treatment for advanced PD patients, and the beneficial effect is maintained at 5 years. However, worsening occurs over time due to disease progression.

Deep Brain Stimulation

BACKGROUND

Deep brain stimulation (DBS) for the treatment of neurologic diseases has markedly increased in popularity over the past 15 years. This review primarily focuses on movement disorder applications and efficacy of DBS, but also briefly reviews other promising new and old uses of DBS.

REVIEW SUMMARY

A multidisciplinary team consisting of a movement disorders neurologist, a functional neurosurgeon, and a neuropsychologist optimally selects patients for DBS. Patients must be significantly disabled despite optimal medical therapy and be cognitively healthy without significant psychiatric disorders. Although this surgery is elective, it should not be withheld until the patient suffers marked loss of quality of life. Patients must have support from caregivers and postoperatively multiple DBS programming visits may be required. DBS of the subthalamic nucleus (STN) and the globus pallidus pars interna (GPi) significantly improves motor performance, activities of daily living, and quality of life in advanced Parkinson disease. In addition, STN DBS allows for marked reductions of antiparkinson medication. Stimulation of the ventralis intermedius nucleus of the thalamus is an effective treatment for essential tremor with sustained long-term effects. The GPi may be the preferred site of stimulation for dystonia with movement scores typically improved by 75% in patients with primary dystonia.

CONCLUSIONS

DBS is an effective surgical treatment for movement disorders with sustained long-term benefits. Further research is ongoing to better understand the mechanism of DBS, refine the hardware to improve efficacy and reduce adverse effects, and identify additional applications and new anatomic targets.

Deep brain stimulation and continuous dopaminergic stimulation in advanced Parkinson's disease

Patients receiving oral levodopa, the standard treatment for Parkinson's disease (PD), eventually develop motor fluctuations and dyskinesias. Treatment options for patients with these symptoms include high-frequency deep brain stimulation of the subthalamic nucleus (STN-DBS) or continuous dopaminergic stimulation (CDS). STN-DBS is the prevalent surgical therapy for PD and has shown efficacy, but behavioural disorders, including cognitive problems, depression and suicidality have been reported. CDS can be achieved with oral dopamine agonists with a long half-life, transdermal or subcutaneous delivery of dopamine agonists, or intestinal levodopa infusion. Of these, duodenal levodopa infusion appears to be the most promising option in terms of both efficacy and safety.

Effects of STN DBS on rigidity in Parkinson's disease

We quantified the effects of deep brain stimulation (DBS) of the subthalamic nucleus (STN) and medication on Parkinsonian rigidity using an objective measure of work about the elbow joint during a complete cycle of imposed 1-Hz sinusoidal oscillations. Resting and activated rigidity were analyzed in four experimental conditions: 1) off treatment; 2) on DBS; 3) on medication; and 4) on DBS plus medication. Rigidity at the elbow joint was also assessed using the Unified Parkinson's Disease Rating Scale (UPDRS). We tested ten patients who received STN DBS and ten age-matched neurologically healthy control subjects. The activated rigidity condition increased work in both Parkinson's disease (PD) patients and control subjects. In PD patients, STN DBS reduced both resting and activated rigidity as indicated by work and the UPDRS rigidity score. This is the first demonstration that STN stimulation reduces rigidity using an objective measure such as work. In contrast, the presurgery dose of antiparkinsonian medication did not significantly improve the UPDRS rigidity score and reduced work only in the activated rigidity condition. Our results suggest that STN DBS may be more effective in alleviating rigidity in the upper limb of PD patients than medications administered at presurgery dosage level.

Sialorrhea in Parkinson's disease: A review

A significant number of patients with Parkinson's disease (PD) experience sialorrhea. This problem can cause social embarrassment, and because saliva pools in the mouth, may lead to aspiration pneumonia. Sialorrhea in PD is thought to be caused by impaired or infrequent swallowing, rather than hypersecretion. Oral medications, botulinum toxin injections, surgical interventions, radiotherapy, speech therapy, and trials of devices may be used to treat sialorrhea in PD, but few controlled trials have been published. This article reviews current knowledge regarding the frequency, etiology, assessment, and treatment of sialorrhea in PD.

Intervening in the neuropsychiatric features of Parkinson's disease

Although Parkinson's disease is considered a movement disorder, it has a wide range and high prevalence of affective, psychotic, cognitive, behavioral and sleep-related features. To treat such features, agents including antidepressants, anxiolytics, antipsychotics and cognition-enhancing agents are commonly prescribed, although the targeted syndromes are often incompletely understood and controlled studies demonstrating a treatment's efficacy and tolerability in Parkinson's disease patients are often lacking. Nevertheless, the available information does suggest the outlines of management methods, pending expanded research to identify optimal strategies specific to Parkinson's disease.

Management of the behavioral aspects of Parkinson's disease

Parkinson's disease is a progressive and debilitating movement disorder that is diagnosed by its motor signs. The behavioral manifestations of Parkinson's disease are prevalent and frequently complicate the course of the disease. These may be due to the illness itself or its treatment and are often more disabling than the motor symptoms. This review focuses on the management of the most common behavioral symptoms of Parkinson's disease, including depression, anxiety, psychosis, dementia, delirium, sleep disorders, fatigue, apathy, emotionalism and compulsive behaviors.

Deep brain stimulation and the role of the neuropsychologist

Deep brain stimulation (DBS) now plays an important role in the treatment of Parkinson's disease, tremor, and dystonia. DBS may also have a role in the treatment of other disorders such as obsessive-compulsive disorder, Tourette's syndrome, and depression. The neuropsychologist plays a crucial role in patient selection, follow-up, and management of intra-operative and post-operative effects (Pillon, 2002; Saint-Cyr & Trepanier, 2000). There is now emerging evidence that DBS can induce mood, cognitive, and behavioral changes. These changes can have dramatic effects on patient outcome. There have been methodological problems with many of the studies of DBS on mood, cognition, and behavior. The neuropsychologist needs to be aware of these issues when following up patients, and constructing future studies. Additionally, this article will review all aspects of the DBS procedure that can result in mood, cognitive, and behavioral effects and what role(s) the neuropsychologist should play in screening and follow-up.

Does ageing influence deep brain stimulation outcomes in Parkinson's disease?

We sought to define the influence of ageing in clinical, cognitive, and quality-of-life outcomes after subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson's disease (PD). We performed motor assessment (UPDRS), mood tests, cognitive, and quality of life evaluation (PDQ-39) on PD patients before surgery, and 12 and 24 months after, and we recorded adverse events. The variations of these parameters after surgery were correlated with age using regression statistical tests. Cerebral bleeding risk was evaluated by a nonparametric test. We enrolled 45 patients (mean age 60 +/- 9 years, range 40-73). No significant correlation was found between age and motor scores and PDQ-39 improvements at 12 months. At 24 months, there was a significant negative correlation between age and the improvement of three dimensions of PDQ 39 (mobility, activities of daily life, and cognition). Cognitive impairment showed no correlation, but apathy and depression were positively correlated with age. Significant statistical difference was observed between cerebral bleeding and age. STN-DBS is an effective treatment for elderly patients with advanced PD. A longer follow-up duration and a larger population seem necessary to better assess the quality of life perception in elderly patients and to determinate the real risk of hemorrage.

Are there adaptive changes in the human brain of patients with Parkinson’s disease treated with long-term deep brain stimulation of the subthalamic nucleus? A 4-year follow-up study with regional cerebral blood flow SPECT

PURPOSE

The aim of this follow-up study was to assess persistent motor and regional cerebral blood flow (rCBF) changes in patients with Parkinson's disease (PD) treated with high-frequency deep brain stimulation (DBS) of the subthalamic nucleus (STN).

METHODS

Ten PD patients with STN-DBS underwent three rCBF SPECT studies at rest, once preoperatively in the off-drug condition (T(0)), and twice postoperatively in the off-drug/off-stimulation conditions at 5 +/- 2 (T(1)) and 42 +/- 7 months (T(2)). Patients were assessed using the UPDRS, H&Y and S&E scales. SPM was used to investigate baseline rCBF changes from the preoperative condition to the postoperative conditions and the relationship between rCBF and UPDRS scores used as covariate of interest.

RESULTS

Parkinsonian patients showed a clinical improvement which was significant only on follow-up at 42 months. The main effect of treatment from T(0) to T(1) was to produce baseline rCBF increases in the pre-supplementary motor area (pre-SMA), premotor cortex and somatosensory association cortex. From T(1) to T(2) a further baseline rCBF increase was detected in the pre-SMA (p < 0.0001). A correlation was detected between the slight improvement in motor scores and the rCBF increase in the pre-SMA (p < 0.0001), which is known to play a crucial role in clinical progression.

CONCLUSION

Our study suggests the presence of adaptive functional changes in the human brain of PD patients treated with long-term STN-DBS. Such adaptive processes seem to occur in the pre-SMA and to play only a slightly beneficial role in terms of functional compensation of motor impairment.

Levodopa response in long-term bilateral subthalamic stimulation for Parkinson's disease

Subthalamic nucleus deep brain stimulation (STN-DBS) is effective in advanced Parkinson's disease (PD), but its effects on the levodopa response are unclear. We studied the levodopa response after long-term STN-DBS, STN-DBS efficacy and predictive value of preoperative levodopa response to long-term DBS benefit in 33 PD patients with bilateral STN-DBS. Patients were assessed using the Unified Parkinson's Disease Rating Scale preoperatively (with and without medications) and postoperatively (without medications or stimulation, with only medications or stimulation, and with both medications and stimulation). Levodopa response significantly decreased postoperatively by 31.1% at 3 years and 32.3% at 5 years, possibly related to the reduction in medication requirement, direct STN stimulation effect or PD progression. STN-DBS alone significantly improved motor scores (37.2% at 3 years and 35.1% at 5 years) and activities of daily living scores (27.1% at 3 years and 19.2% at 5 years). Anti-PD drugs were significantly reduced by 47.9% at 3 years and 39.8% at 5 years. However, the magnitude of the preoperative response to levodopa did not predict DBS benefit at 3 and 5 years.

Cognitive outcome 5 years after bilateral chronic stimulation of subthalamic nucleus in patients with Parkinson's disease

AIM

To assess the long-term cognitive and behavioural outcome after bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) in patients affected by Parkinson's disease, with a 5-year follow-up after surgery.

METHODS

11 patients with Parkinson's disease treated by bilateral DBS of STN underwent cognitive and behavioural assessments before implantation, and 1 and 5 years after surgery. Postoperative cognitive assessments were carried out with stimulators turned on.

RESULTS

A year after surgery, there was a marginally significant decline on a letter verbal fluency task (p = 0.045) and a significant improvement on Mini-Mental State Examination (p = 0.009). 5 years after surgery, a significant decline was observed on a letter verbal fluency task (p = 0.007) and an abstract reasoning task (p = 0.009), namely Raven's Progressive Matrices 1947. No significant postoperative change was observed on other cognitive variables. No patient developed dementia 5 years after surgery. A few days after the implantation, two patients developed transient manic symptoms with hypersexuality and one patient developed persistent apathy.

CONCLUSION

The decline of verbal fluency observed 5 years after implantation for DBS in STN did not have a clinically meaningful effect on daily living activities in our patients with Parkinson's disease. As no patient developed global cognitive deterioration in our sample, these findings suggest that DBS of STN is associated with a low cognitive and behavioural morbidity over a 5-year follow-up, when selection criteria for neurosurgery are strict.

Bilateral subthalamic nucleus stimulation in advanced Parkinson's disease: three years follow-up

OBJECTIVE

To assess the long-term efficacy and safety of chronic bilateral stimulation of the subthalamic nucleus (STN) in patients with advanced Parkinson's disease (PD).

METHODS

36 consecutive patients with idiopathic Parkinson's disease treated with bilateral stimulation of the STN were studied. Parkinsonian status was assessed preoperatively and at 1 and 3 years postoperatively using the Unified Parkinson's Disease Rating Scale (UPDRS) and neuropsychological evaluation in on and off-medication / on and off stimulation conditions.

RESULTS

At 3 years follow-up, STN stimulation reduced the UPDRS motor score by 54.2 % compared to baseline in the off-medication conditions. Tremor, rigidity, bradykinesia, postural stability, and gait improved by 72.2 %, 62.4 %, 56.8 %, 40.5 % and 45.3 %, respectively. UPDRS part II scores were reduced by 41.4 %. The overall dopaminergic drugs dose was reduced by 48.6 % after surgery and four patients were no longer taking antiparkinsonian medication at three years. However, axial dopa-unresponsive signs worsened in some patients. The most frequent transient adverse event consisted in mood disorders in 23 patients.

CONCLUSIONS

Our data demonstrate that: 1) bilateral STN stimulation is relatively safe, improves the motor symptoms and drug-related motor complications of PD, and reduces the daily dosage of medication; 2) this benefit is sustained over time despite the occurrence of axial doparesistant signs in some patients.

Deep brain stimulation in neurologic disorders

Deep brain stimulation (DBS) is an effective surgical therapy for well-selected patients with medically intractable Parkinson's disease (PD) and essential tremor (ET). The purpose of this review is to describe the success of DBS in these two disorders and its promising application in dystonia, Tourette Syndrome (TS) and epilepsy. In the last 10 years, numerous short- and intermediate-term outcome studies have demonstrated significant relief to patients with PD and ET. A few long-term follow-up studies have also reported sustained benefits. When successful, DBS greatly reduces most of parkinsonian motor symptoms and drug-induced dyskinesia, and it frequently improves patients' ability to perform activities of daily living with less encumbrance from motor fluctuations. Quality of life is enhanced and many patients are able to significantly reduce the amount of antiparkinsonian medications required to still get good pharmacological benefit. Overall, adverse effects associated with DBS tend to be transient, although device-related and other postoperative complications do occur. DBS should be considered the surgical procedure of choice for patients who meet strict criteria with medically intractable PD, ET and selected cases of dystonia.

Mortality in patients with Parkinson's disease treated by stimulation of the subthalamic nucleus

Subthalamic nucleus (STN) stimulation improves motor disability and quality of life in patients with advanced Parkinson's disease (PD). Short-term mortality is low, but little is known about long-term mortality. We assessed mortality and causes of death in 171 consecutive PD patients treated by STN stimulation. Surgery was performed after a median lagtime of 13 years from PD onset at a median age of 57 years. The median follow-up after surgery was 41 months. Sixteen patients died 8 to 83 months after neurosurgery. Poorer cognitive function was the only predictive factor for mortality (standardized mortality ratio = 2.9; 95% confidence interval [CI], 1.6-4.7; P < 0.0001). Based on a historical comparison of 118 operated patients with 39 nonoperated patients from a different population, survival among operated patients was not better (hazard ratio = 1.2; 95% CI, 0.7-2.1).

Deep brain stimulation for Parkinson's disease

Indications for the treatment of Parkinson's disease (PD) with deep brain stimulation (DBS) are severe, therapy refractory tremor and complications of long-term levodopa uptake. Since its first application DBS has become a standard therapy for these patients. Theoretically, the ventrolateral part of the internal pallidum (GPI) or the subthalamic nucleus (STN) are suitable targets in order to treat all cardinal symptoms of patients in an advanced stage of PD stereotactically. Although clinical efficacy of both GPI or STN stimulation is obviously comparable, it has become widely accepted to prefer STN over GPI DBS. If PD-associated, medically intractable tremor is the most disabling symptom, stimulation of the ventrolateral motor thalamus can be an alternative. Anatomical targets for DBS are small and located in critical brain areas. Furthermore, this type of surgery is highly elective. As a consequence, high resolution multiplanar imaging and adequate treatment planning software are indispensable prerequisites for DBS surgery. Currently, commercially available impulse generators deliver a permanent high frequency periodic pulse train stimulation that interacts rather unspecifically with the firing pattern of both normal and pathological neurons. Prospectively, the development of more specific stimulation paradigms may help to improve the efficacy of this treatment modality.

Correlation between the Anatomical and Functional Human Subthalamic Nucleus

This work addresses the spatial correlation between the anatomical and functional human subthalamic nucleus (STN). The anatomical STN (A-STN), derived from the Schaltenbrand-Wahren brain atlas, is histology based. The functional STN (F-STN) is probabilistic, constructed from neuroelectrophysiological and neuroimaging data of 184 Parkinson's disease patients. The A-STN and F-STN are placed in the same space and compared in terms of mutual relative overlapping of anatomy with function. The F-STN and A-STN correlate well for medium and high probabilities of the F-STN. For probability p >or= 0.3, >95% of F-STN is inside the A-STN, and for p >or= 0.5, the complete F-STN is inside the A-STN for each left and right STN. Therefore, the F-STN for p = 0.5 can potentially be used for identification of the STN in neuroimages.

Unilateral pallidotomy versus bilateral subthalamic nucleus stimulation in Parkinson's disease: one year follow-up of a randomised observer-blind multi centre trial

BACKGROUND

To investigate whether STN stimulation is more efficacious than unilateral pallidotomy in advanced Parkinson's disease (PD) one year after surgery.

METHOD

Thirty-four patients with advanced PD were randomly assigned to unilateral pallidotomy or bilateral STN stimulation. Outcome measures were parkinsonian symptoms in off and on phases (UPDRS 3), dyskinesias, functional status, Parkinson's disease quality of life questionnaire, the effects on separate symptoms, timed tests, patient diaries, dopaminergic drugs changes, adverse effects, and global outcome scale. Patients were assessed before surgery, six months and one year after surgery. The primary outcome measure was the off phase UPDRS 3 at six months follow-up.

FINDINGS

The off phase UPDRS 3 score improved from 46.5 to 32 points in the pallidotomy patients and from 51.5 to 24 in the STN stimulation patients (p = 0.002). On phase UPDRS 3 and off phase Schwab and England functional scale improved significantly in favour of the STN stimulation patients. Dopaminergic drugs reduction was larger in the STN group although the difference between the treatment groups was not significant. One patient in each group had a major adverse effect.

CONCLUSIONS

Bilateral STN stimulation is more efficacious than unilateral pallidotomy in advanced PD up to one year after surgery.

Gait Changes in Response to Subthalamic Nucleus Stimulation in People with Parkinson Disease

BACKGROUND AND PURPOSE

For individuals with advanced Parkinson disease (PD), stimulation of the subthalamic nucleus (STN) reduces tremor, rigidity, and bradykinesia, but the effects of stimulation on gait and mobility are not fully understood. The purpose of this paper is to describe the effects of unilateral and bilateral STN stimulation on gait following staged stimulator implantations in a series of individuals with PD.

CASE DESCRIPTIONS

Participants were 6 individuals with PD who underwent staged stimulator implantation surgeries. The effects of stimulation on gait were assessed in the optimally medicated state using items from the Unified Parkinson's Disease Rating Scale (UPDRS) related to gait and self-reported mobility, time to complete the Timed Up and Go (TUG) test, and quantitative gait analysis. Gait was evaluated with stimulation turned off and with stimulation turned on after unilateral stimulator implantation and again after implantation of the second stimulator.

OUTCOMES

Variable effects of unilateral and bilateral STN stimulation on gait were observed on UPDRS self-reported mobility, TUG time, and gait velocity, but changes were not detected using the UPDRS gait item. Minimal gait changes, either positive or negative, were detected with unilateral stimulation. With bilateral stimulation, gait improved for 3 individuals but worsened for the other 3 individuals.

DISCUSSION

The ability to detect changes in gait after STN stimulation using the UPDRS gait item was limited, but variable effects were detected by self-report, TUG time, and gait velocity. For half of the individuals studied, bilateral stimulation improved these measures, but gait worsened for the remaining individuals. Future research is needed to better understand factors that influence the effect of STN stimulation on walking, and assessment of gait changes in people with PD should include self-report and performance-based measures, such as the TUG test or gait velocity.

Hardware-Related Complications of Deep Brain Stimulation: A Review of the Published Literature

Hardware-related complications have been commonly described after deep brain stimulation. We searched the PubMed database using the key words 'adverse effects' and 'deep brain stimulation'. Out of 254 studies, we identified 10 articles that primarily addressed morbidity and hardware-related adverse effects in 922 patients. The most commonly reported hardware-related complications were infections (6.1% of the patients), migration or misplacement of the leads (5.1% of the patients), lead fractures (5.0% of the patients), and skin erosion (1.3% of the patients). Refinements in surgical technique, technological improvements, and a greater experience with the procedures will likely decrease the incidence of hardware-related side effects in the future.

Surgical Treatment of Movement Disorders

A substantial body of evidence has accumulated regarding the efficacy and safety of neurosurgery for Parkinson's disease, essential tremor, and dystonia. Surgery for movement disorders (thalamotomy, pallidotomy, and subthalamic nucleotomy or subthalamotomy) was largely ablative (lesion-based). Given the safety and anatomy-preservation advantage, long-term electrical stimulation of these same targets (thalamus, globus pallidus, and subthalamic nucleus) is discussed as the treatment of choice. High-frequency deep brain stimulation procedures replicate the effects of ablative interventions, but do not require making a destructive brain lesion. This article outlines patient eligibility for surgery, targeting techniques, intraoperative findings, and potential complications and discusses the outcomes expected for each of the major interventions for which clinical trial data are available.

Bilateral effects of unilateral subthalamic nucleus deep brain stimulation in advanced Parkinson's disease

To investigate the bilateral effects of unilateral subthalamic nucleus deep brain stimulation (STN-DBS), we prospectively studied 9 consecutive advanced Parkinson's disease (PD) patients (2 men and 7 women) who underwent unilateral STN-DBS. Patients were evaluated preoperatively and at 3 and 6 months postoperatively with and without dopaminergic medications ('on' and 'off' medication, respectively). Postoperatively, patients were assessed with and without stimulation. We found that, when compared with baseline, the 'off' medication scores of the Unified Parkinson's Disease Rating Scale motor part (UPDRS III) and activities of daily living (UPDRS II) were improved by 37% (p = 0.028) and 50% (p = 0.046) at 6 months after surgery, respectively. Stimulation while 'off' medication improved the total UPDRS score by 42% (p = 0.028) at 6 months. At 6 months after surgery, the subscore of UPDRS III of body parts contralateral to the DBS implantation had improved by 48% (p = 0.028), and the ipsilateral subscore of UPDRS III and the axial subscore of UPDRS III had improved by 20% (p = 0.027) and 39% (p = 0.028), respectively. Daily dosage of levodopa was reduced by 15% at 6 months. No patient exhibited permanent side effects. These findings indicate that unilateral STN-DBS may be a reasonable surgical procedure for selected PD patients who have markedly asymmetric parkinsonism.

A randomized trial of deep-brain stimulation for Parkinson's disease

BACKGROUND

Neurostimulation of the subthalamic nucleus reduces levodopa-related motor complications in advanced Parkinson's disease. We compared this treatment plus medication with medical management.

METHODS

In this randomized-pairs trial, we enrolled 156 patients with advanced Parkinson's disease and severe motor symptoms. The primary end points were the changes from baseline to six months in the quality of life, as assessed by the Parkinson's Disease Questionnaire (PDQ-39), and the severity of symptoms without medication, according to the Unified Parkinson's Disease Rating Scale, part III (UPDRS-III).

RESULTS

Pairwise comparisons showed that neurostimulation, as compared with medication alone, caused greater improvements from baseline to six months in the PDQ-39 (50 of 78 pairs, P=0.02) and the UPDRS-III (55 of 78, P<0.001), with mean improvements of 9.5 and 19.6 points, respectively. Neurostimulation resulted in improvements of 24 to 38 percent in the PDQ-39 subscales for mobility, activities of daily living, emotional well-being, stigma, and bodily discomfort. Serious adverse events were more common with neurostimulation than with medication alone (13 percent vs. 4 percent, P<0.04) and included a fatal intracerebral hemorrhage. The overall frequency of adverse events was higher in the medication group (64 percent vs. 50 percent, P=0.08).

CONCLUSIONS

In this six-month study of patients under 75 years of age with severe motor complications of Parkinson's disease, neurostimulation of the subthalamic nucleus was more effective than medical management alone. (ClinicalTrials.gov number, NCT00196911 [ClinicalTrials.gov].).

Targets for deep brain stimulation in Parkinson's disease

The use of stimulation electrodes implanted in the brain to control severely disabling neurological and psychiatric conditions is an exciting and fast emerging area of neuroscience. An excellent example is Parkinson's disease (PD), in which tens of thousands of patients have now been implanted with stimulation electrodes. Patients with PD underwent deep brain stimulation (DBS) at the level of the thalamus, globus pallidus internus, subthalamic nucleus, pedunculopontine nucleus and prelemniscal radiation. The results of these interventions revealed that each target has its own specific stimulation-related positive and negative effects. Clinicians can choose their DBS target based on the situation of their individual PD patients. In the authors' opinion, patient-specific targeting should be preferred over disease-specific targeting. In this review, the authors give an overview of the targets that have been used for DBS in PD and discuss patient-specific targeting.

Cognitive sequelae of subthalamic nucleus deep brain stimulation in Parkinson's disease: a meta-analysis

BACKGROUND

Deep brain stimulation of the subthalamic nucleus (STN DBS) is an increasingly common treatment for Parkinson's disease. Qualitative reviews have concluded that diminished verbal fluency is common after STN DBS, but that changes in global cognitive abilities, attention, executive functions, and memory are only inconsistently observed and, when present, often nominal or transient. We did a quantitative meta-analysis to improve understanding of the variability and clinical significance of cognitive dysfunction after STN DBS.

METHODS

We searched MedLine, PsycLIT, and ISI Web of Science electronic databases for articles published between 1990 and 2006, and extracted information about number of patients, exclusion criteria, confirmation of target by microelectrode recording, verification of electrode placement via radiographic means, stimulation parameters, assessment time points, assessment measures, whether patients were on levodopa or dopaminomimetics, and summary statistics needed for computation of effect sizes. We used the random-effects meta-analytical model to assess continuous outcomes before and after STN DBS.

FINDINGS

Of 40 neuropsychological studies identified, 28 cohort studies (including 612 patients) were eligible for inclusion in the meta-analysis. After adjusting for heterogeneity of variance in study effect sizes, the random effects meta-analysis revealed significant, albeit small, declines in executive functions and verbal learning and memory. Moderate declines were only reported in semantic (Cohen's d 0.73) and phonemic verbal fluency (0.51). Changes in verbal fluency were not related to patient age, disease duration, stimulation parameters, or change in dopaminomimetic dose after surgery.

INTERPRETATION

STN DBS, in selected patients, seems relatively safe from a cognitive standpoint. However, difficulty in identification of factors underlying changes in verbal fluency draws attention to the need for uniform and detailed reporting of patient selection, demographic, disease, treatment, surgical, stimulation, and clinical outcome parameters.

Control of dopamine-secretion by Tet-Off system in an in vivo model of parkinsonian rat

We established a PC12 cell line (PC12TH Tet-Off) in which human tyrosine hydroxylase (TH) expression can be negatively controlled by Doxycycline (Dox). First, dopamine (DA)-secretion from PC12TH Tet-Off cells was controlled by Dox-administration in a dose-responsive manner ranging from 0 to 100 ng/ml for 70 days in vitro. Furthermore, Parkinson's disease model of rats receiving encapsulated PC12TH Tet-Off cells displayed a significant decrease of dopamine concentration in the cerebrospinal fluid (CSF) and increase of the number of apomorphine-induced rotations by Dox-administration, as compared to transplanted rats without Dox-administration, although the significant decrease of the reduction ratio of DA concentration in the CSF with Dox-administration was recognized over time. At 2 months post-implantation, concentration of dopamine in the implanted striatum and from the retrieved capsules demonstrated that the control of DA-secretion could be partially achieved for 2 months in vivo. Our results support both the value of cell therapy using Tet-Off system and the technique of encapsulation might be a feasible option for Parkinson's disease especially in resolving the problem of dopamine oversupply in the future, although a more efficient way to control DA-secretion with quicker regulation and much titration of dose should be explored before clinical application.

Quantification and Visualization of the Three-Dimensional Inconsistency of the Subthalamic Nucleus in the Schaltenbrand-Wahren Brain Atlas

The Schaltenbrand-Wahren (SW) brain atlas has many limitations: the major two are three-dimensional (3D) inconsistency and spatial sparseness. In this work, we quantify and visualize the 3D inconsistency of the subthalamic nucleus (STN). The STN 3D models, 3D-A, 3D-C and 3D-S, are reconstructed from the SW axial, coronal, and sagittal microseries, respectively, by using a shape-based (NURBS) approach. All three models are placed in the SW coordinate system and compared quantitatively in terms of location (centroids), size (volumes), shape (normalized eigenvalues), orientation (eigenvectors), and mutual spatial relationships (overlaps and inclusions). Analysis is done in 3D within each orientation and across them. A dedicated tool is developed for quantitative validation of 3D modeling. The average error achieved is 0.088 mm, which is at the resolution limit of the digital SW atlas. The reconstructed 3D STN models differ in location, size, shape, orientation, overlap size, and inclusion rate. The 3D-S volume is 1.27 times larger than that of 3D-A and 1.38 times larger than that of 3D-C. The highest overlap size is found between 3D-A and 3D-S. The highest inclusion rates of 52.5 and 66.6% are for 3D-A and 3D-S. 3D-C has the lowest overlap size and results in the lowest inclusion rates (around 20-30%), meaning that 3D-C is substantially displaced in comparison to 3D-A and 3D-S. The lateral centroid coordinate of 3D-C is 9.18 mm while that of 3D-S is 12.17 mm. Each of the 3D models has some limitation: 3D-A in orientation, 3D-C in location, and 3D-S in shape realism. The STN in comparison to the actual almond is smaller, and relatively (i.e. normalized to the same height) 2.2-2.4 times wider and 3.7-5.5 times longer. 3D-C becomes more similar to 3D-S by scaling the SW coronal microseries laterally by 1.3257. Then the lateral coordinates of their centroids coincide, the difference between them in orientation is 0.11 mm, and 3D-S is only 1.06 times larger than the scaled 3D-C. This operation substantially improves registration of the SW atlas with the probabilistic functional atlas. However, 3D visualization shows that both 3D-S and scaled 3D-C models are heavily interwoven resulting in low inclusion rates of about 60%. The STN in the SW atlas shows severe 3D inaccuracy within each orientation and across them, and it has to be employed with great care and understanding of its limitations.

Pathological gambling in Parkinson's disease improves on chronic subthalamic nucleus stimulation

Pathological gambling (PG) related to dopaminergic treatment in Parkinson's disease (PD) is part of a spectrum of behavioral disorders called the dopamine dysregulation syndrome (DDS). We describe a series of PD patients with preoperative active PG due to dopaminergic treatment from a total of 598 patients who have undergone surgery for subthalamic nucleus stimulation for disabling motor fluctuations. The patients had systematic open assessment of behavioral symptoms and standardized assessments of motor symptoms, mood, and apathy. Seven patients (6 men, 1 woman; age, 54 +/- 9 years; levodopa equivalent dose, 1,390 +/- 350 mg/day) had preoperative PG over a mean of 7 years, intolerant to reduction in medication. Six had nonmotor fluctuations and four had other behavioral symptoms consistent with a diagnosis of the DDS. After surgery, motor symptoms improved, allowing for 74% reduction of dopaminergic treatment, below the dosage of gambling onset. In all patients, PG resolved postoperatively after 18 months on average (range, 0-48), although transient worsening occurred in two. Improvement paralleled the time course and degree of reduction in dopaminergic treatment. Nonmotor fluctuations, off period dysphoria, and other symptoms of the DDS improved. Two patients developed persistent apathy. In conclusion, PG and other symptoms of the DDS-associated dopaminergic treatment improved in our patients following surgery. Dopaminergic dysregulation commonly attributed to pulsatile overstimulation of the limbic dopaminergic system may be subject to desensitization on chronic subthalamic stimulation, which has a relative motor selectivity and allows for decrease in dopaminergic treatment.