Parkinson's disease motor subtypes and bilateral GPi deep brain stimulation: One-year outcomes

ObjectiveWe aimed to explore the differences in motor symptoms and quality of life (QOL) outcomes following bilateral globus pallidus internus deep brain stimulation (GPi DBS), across well-defined motor subtypes of Parkinson's disease (PD), to improve clinical decision making.MethodsThis single-center retrospective study investigated bilateral GPi DBS outcomes in 65 PD patients. Outcome measures included the Unified Parkinson's Disease Rating Scale (UPDRS) and Parkinson's Disease Questionnaire (PDQ-39) before and one year after surgery. Outcomes were compared between the tremor-dominant (TD) and postural instability and gait difficulty (PIGD) subtypes and between the TD and akinetic-rigid (AR) subtypes.ResultsFor the entire cohort, motor function (UPDRS III) in the Off-medication state, motor complications (UPDRS IV), activities of daily living (ADL, UPDRS II), and the ADL and discomfort domains of PDQ-39 significantly improved one year following GPi implantation compared to baseline (effect size = 1.32, 1.15, 0.25, 0.45, and 0.34, respectively). GPi DBS improved the Off-medication UPDRS III scores regardless of the motor subtypes. However, compared to the PIGD and AR patients, the TD patients showed greater improvement in overall UPDRS III postoperatively primarily due to greater tremor improvement in the Off-medication state. The outcomes in akinesia, rigidity, axial symptoms and QOL were similar among all subtypes.ConclusionBilateral GPi DBS was effective for advanced PD patients regardless of motor subtypes. Greater tremor improvement in the TD patients accounted for greater Off-medication motor improvement. Longer-term GPi DBS outcomes across different motor subtypes and brain targets should be further studied.     

Low-frequency deep brain stimulation for movement disorders

IntroductionTraditionally, deep brain stimulation (DBS) for movement disorders (MDs) is provided using stimulation frequencies equal to or above 100 Hz. However, recent evidence suggests that relatively low-frequency stimulation (LFS) below 100 Hz is an option to treat some patients with MDs.ObjectivesWe aimed to review the clinical and pathophysiological evidence supporting the use of stimulation frequencies below 100 Hz in different MDs.ResultsStimulation of the subthalamic nucleus at 60 Hz has provided benefit in gait and other axial symptoms such as swallowing and speech. Stimulation of the pedunculopontine nucleus between 20 and 45 Hz can provide benefit in freezing of gait, cognition, and sleep quality in select patients with Parkinson's disease. Stimulation of the globus pallidus internus below 100 Hz in patients with dystonia has provided benefit at the beginning of the therapy, although progressively higher stimulation frequencies seem to be necessary to maintain the clinical benefit. Relative LFS can lower energy requirements and reduce battery usage—a useful feature, particularly in patients treated with high current energy.ConclusionsDBS at frequencies below 100 Hz is a therapeutic option in select cases of Parkinson's disease with freezing of gait and other axial symptoms, and in select patients with dystonia and other hyperkinetic movements, particularly those requiring an energy-saving strategy.     

Pallidal deep brain stimulation in the treatment of Meige syndrome

Background –  Pallidal deep brain stimulation (DBS) of globus pallidus internus (Gpi) has emerged as an effective treatment for dystonia. The experience is however limited concerning focal dystonias and to date only a few cases of pallidal DBS in the treatment of Meige syndrome have been published.
Methods/results –  We here present a patient with Meige syndrome in whom unilateral pallidal DBS failed to improve the axial symptoms, but bilateral stimulation resulted in a major improvement. The Burke-Fahn-Marsden score (BFM) improved by 71.5% and the patient's blepharospasm was abolished.
Conclusions –  The results suggest bilateral pallidal DBS may be an effective treatment for Meige syndrome.     

Globus pallidus deep brain stimulation for refractory idiopathic restless legs syndrome

ObjectiveThe neuroanatomic substrate of restless legs syndrome (RLS) is unknown. Deep brain stimulation (DBS) of the globus pallidus internus (GPi) and other targets is used to treat Parkinson’s disease (PD), and RLS symptoms associated with PD have been reported to improve when GPi DBS is used in that population. We wish to test whether GPi DBS can improve idiopathic RLS.MethodWe implanted bilateral GPi DBS in a subject with refractory idiopathic RLS.ResultsThe GPi cells recordings were dissimilar to those of PD. Clinically, the patient had a good, but far from complete, response, which more prominently affected the urge to move and involuntary movements than the painful component.ConclusionDBS for RLS remains investigational.     

DBS in restless legs syndrome: a new therapeutic approach?

ObjectiveRestless legs syndrome (RLS) is a sleep disorder characterized by an urge to move legs or arms, with a typical circadian rhythm. RLS can be treated with pharmacological and non-pharmacological therapies. Nevertheless, in some patients RLS can be refractory to all medical and non-medical treatments.Deep brain stimulation (DBS) of the globus pallidus internus (GPi) has been reported to improve RLS symptoms in Parkinson's disease (PD) patients with RLS. We describe the case of a patient suffering from refractory idiopathic RLS implanted with bilateral GPi DBS.MethodThe patient underwent DBS targeting the bilateral GPi. Follow up for three years involved clinical evaluation and polysomnography (PSG).ResultsThe patient reported subjective improvement, with reduction in the IRLS score. Furthermore, the polysomnography (PSG) showed an objective improvement of polysomnographic parameters, which remained stable during the follow-up.ConclusionDBS for RLS can be a new therapeutic approach for severe RLS, but further studies are needed.     

Effects of Pedunculopontine Area and Pallidal DBS on Gait Ignition in Parkinson's Disease

BackgroundFreezing of gait is a disabling feature of Parkinson's disease, and so far no established treatment exists. Deep brain stimulation of the pedunculopontine area has been proposed to treat refractory gait disorders, yet data on measurable effects, especially in combination with stimulation of other targets, are scarce.MethodsAcute effects of either low frequency pedunculopontine stimulation or high frequency stimulation of the posteroventral lateral globus pallidus internus and a combination of both in a 66-year-old man with advanced Parkinson's disease were assessed. Four weeks after the intervention, the gait was examined with patient blinded in each condition using computerized gait analysis.ResultsIsolated pedunculopontine or pallidal stimulation had a mild impact on gait ignition and freezing of gait, but combined stimulation had a marked effect.ConclusionsCombined multifocal stimulation may be a promising option for gait ignition and freezing of gait in advanced Parkinson's disease.     

Stimulation Region Within the Globus Pallidus Does Not Affect Verbal Fluency Performance

BackgroundSubthalamic (STN) and globus pallidus (GP) deep brain stimulation (DBS) have been previously shown to be efficacious in the treatment of selected Parkinson patients with medication resistant motor fluctuations and/or tremor. Deep brain stimulation of the STN has been implicated with more cognitive and mood side effects as compared to GP DBS; however, more studies are needed to better understand possible target differences. Previously, Mikos et al. [1] reported worsening of verbal fluency depending on the stimulation location within the STN region.Objective/hypothesisThe current study applied the methods used by Mikos et al. (2011) to a different sample of Parkinson patients who underwent GP DBS. Based on differences in the size and functional somatotopy between structures (GP 412 mm³ vs. STN 167 mm³), we hypothesized that there would be a less robust relationship between volume of tissue activated, fluency performance, and stimulation contact within the GP compared to what was reported in the STN.MethodsPatient-specific DBS models were created and the volume of tissue activated within the GP was calculated. These data were correlated with patients' verbal fluency performance at dorsal, optimal, and ventral stimulation contacts.ResultsIn contrast to STN findings, there was no significant relationship between stimulation location and fluency performance in patients who received GP DBS.Conclusion(s)These results suggest that fluency may be less sensitive to stimulation location in the globus pallidus and thus there may be more flexibility in terms of DBS programming with GP DBS patients.     

Risks of intracranial hemorrhage in patients with Parkinson's disease receiving deep brain stimulation and ablation

ObjectivesThis study analyzed risk factors for hemorrhage in a large series of deep brain stimulation (DBS) and ablation procedures in patients with advanced Parkinson's disease (PD).MethodsSix hundred and forty four subjects with advanced PD treated with DBS or ablation procedures between March 1999 and December 2007 were enrolled in the study. Procedures were performed by the same surgeon, and included DBS in 126 patients, ablation in 507 patients and DBS after prior unilateral ablation procedures in 11 patients. Of 796 target procedures, 207 were DBS including 202 subthalamic nucleus (STN) targets, 3 ventralis intermedius nucleus (Vim) targets and 2 globus pallidus internus (GPi) targets, and the others were 589 ablation procedures including 474 GPi targets and 115 Vim targets. Postoperative CT or MRI was performed in all patients within 24 h of lead implantation or ablation treatment. Statistical correlation analysis of risk factors for intracranial hemorrhage (ICH) was performed by stepwise logistic regression. Explanatory variables were patient age, sex, blood pressure, anatomical targets, the number of microelectrode recording (MER) penetrations and surgical modality.ResultsPostoperative symptomatic ICH occurred in 10 cases (8 pallidotomy and 2 thalamotomy) and asymptomatic ICH in 14 cases (9 pallidotomy, 4 thalamotomy and 1 DBS). Hypertension and surgical modality were significant factors contributing to hemorrhage (both P < 0.05). The likelihood of hemorrhage in hypertensive patients was 2.5 times that in normotensive patients. The risk of hemorrhage during ablation was 5.4 times that in DBS. The number of MER trajectories did not significantly correlate with ICH occurrence (P = 0.07). No statistically significant difference was found in age, sex and anatomical targets.ConclusionThis study demonstrated that hypertension is a risk factor for ICH in PD patients. DBS is generally a safe surgical modality as compared with ablation. Increasing microelectrode trajectories seemed to increase the risk of ICH, but no statistically significant difference was found (P = 0.07).     

Treating post-traumatic tremor with deep brain stimulation: Report of five cases

BackgroundPost-traumatic tremor is one of the most common movement disorders resulting from severe head trauma. However, literature regarding successful deep brain stimulation (DBS) treatment is scarce, resulting in ambiguity regarding the optimal lead location. Most cases support the ventral intermediate nucleus, but there is evidence to defend DBS of the zona incerta, ventral oralis anterior/posterior, and/or a combination of these targets. We report five patients with disabling post-traumatic tremor treated with DBS of the ventral intermediate nucleus and of the globus pallidus internus.MethodsPatients were referred to the Vanderbilt Movement Disorders Division, and surgical intervention was determined by a DBS Multidisciplinary Committee. Standard DBS procedure was followed.ResultsPatients 1–4 sustained severe diffuse axonal injuries. Patients 1–3 underwent unilateral ventral intermediate nucleus DBS for contralateral tremor, while Patient 4 underwent bilateral ventral intermediate nucleus DBS. Patients 1–3 experienced good tremor reduction, while Patient 4 experienced moderate tremor reduction with some dystonic posturing of the hands. Patient 5 had dystonic posturing of the right upper extremity with tremor of the left upper extremity. He was treated with bilateral DBS of the globus pallidus internus and showed good tremor reduction at follow-up.ConclusionUnilateral or bilateral DBS of the ventral intermediate nucleus and bilateral DBS of the globus pallidus internus may be effective and safe treatment modalities for intractable post-traumatic tremor. Further studies are needed to clarify the optimal target for surgical treatment of post-traumatic tremor.     

Weight change following deep brain stimulation for movement disorders

Patients with Parkinson’s disease (PD) and essential tremor (ET) tend to lose weight progressively over years. Weight gain following deep brain stimulation (DBS) of the subthalamic nucleus (STN) for treatment of PD has been documented in several studies that were limited by small sample size and exclusive focus on PD patients with STN stimulation. The current study was undertaken to examine weight change in a large sample of movement disorder patients following DBS. A retrospective review was undertaken of 182 patient charts following DBS of the STN, ventralis intermedius nucleus of the thalamus (VIM), and globus pallidus internus (GPi). Weight was collected preoperatively and postoperatively up to 24 months following surgery. Data were adjusted for baseline weight and multivariate linear regression was performed with repeated measures to assess weight change. Statistically significant mean weight gain of 1.8 kg (2.8% increase from baseline, p = 0.0113) was observed at a rate of approximately 1 kg per year up to 24 months following surgery. This gain was not predicted by age, gender, diagnosis, or stimulation target in a multivariate model. Significant mean weight gain of 2.3 kg (p = 0.0124) or 4.2% was observed in our PD patients. Most patients with PD and ET gain weight following DBS, and this gain is not predicted by age, gender, diagnosis, or stimulation target.     

Randomized double-blind sham-controlled trial of thalamic versus GPi stimulation in patients with severe medically refractory Gilles de la Tourette syndrome

BackgroundThere are still no sufficient data regarding the use of deep brain stimulation (DBS) in Gilles de la Tourette syndrome (GTS) and no agreement on optimal target.ObjectiveTo compare efficacy and safety of bilateral DBS of thalamus (centromedian-ventro-oral internus, CM-Voi) versus posteroventral lateral globus pallidus internus (pvl GPi)) versus sham stimulation, and baseline in severe medically refractory GTS.MethodsIn this randomized double-blind sham stimulation-controlled trial (RCT), 10 patients (3 women, mean age = 29.4 ± 10.2 SD, range 18–47) underwent three blinded periods each lasting three months including (i) sham, (ii) pvl GPi (on-GPi), and (iii) thalamic stimulation (on-thal) followed by an open uncontrolled long-term follow-up (up to 9 years) with individually determined target and stimulation settings.ResultsNine patients completed the RCT. At group level, on-GPi – but not on-thal – resulted in a significant tic reduction compared to baseline, but had no effect on premonitory urges and psychiatric comorbidities. Direct comparisons of targets resulted in inconsistent or negative (compared to sham) findings. During follow-up, we found no improvement of tics, comorbidities, and quality of life at group level, however, single patients benefitted continuously from thalamic DBS. At last follow-up 89.9 months (mean) after surgery, 50% of patients had discontinued DBS. Hardware infections occurred in 3/10 patients.ConclusionOur data suggest that the initial effect of pvl GPi DBS is superior to thalamic (CM-Voi) DBS. While half of the patients discontinued treatment, single patients benefitted from thalamic DBS even after years. It is likely that outcome is influenced by various factors beyond the mere change in tic severity.     

Cortical evoked potentials from pallidal stimulation in patients with primary generalized dystonia

Deep brain stimulation (DBS) of globus pallidus internus (GPi) has emerged as an effective treatment for primary generalized dystonia. However, the physiological mechanisms of improvement are not fully understood. Cortical activity in response to pallidal stimulation was recorded in 6 patients with primary generalized dystonia >6 months after bilateral GPi DBS. Scalp electroencephalogram was recorded using 60 surface electrodes during 10 Hz bipolar pallidal DBS at each electrode contact pair. Anatomical position of the electrode contacts in relation to the GPi, medial medullary lamina and globus pallidus externus (GPe) was determined from the postoperative stereotactic MRI. In all six patients an evoked potential (EP) was observed with average onset latency of 10.9 ms ± 0.77, peak latency 26.6 ms ± 1.6, distributed mainly over the ipsilateral hemisphere, maximal centrally. The mean amplitude of this potential was larger with stimulation in posteroventral GPi than in GPe (3.36 μV vs. 0.50 μV, P < 0.0001). The EP was absent in one patient‐side, ipsilateral to a previous thalamotomy. Low frequency GPi stimulation produces an EP distributed centrally over the ipsilateral hemisphere. The latency and distribution of the EP are consistent with stimulation of pallidothalamic neurons projecting to the sensorimotor cortex. Because the EP is larger and more consistently present with stimulation of posteroventral GPi than GPe, it may provide a physiological tool to identify contacts within the optimal surgical target. © 2007 Movement Disorder Society     

Long‐term results of a multicenter study on subthalamic and pallidal stimulation in Parkinson's disease

We report the 5 to 6 year follow‐up of a multicenter study of bilateral subthalamic nucleus (STN) and globus pallidus internus (GPi) deep brain stimulation (DBS) in advanced Parkinson's disease (PD) patients. Thirty‐five STN patients and 16 GPi patients were assessed at 5 to 6 years after DBS surgery. Primary outcome measure was the stimulation effect on the motor Unified Parkinson's Disease Rating Scale (UPDRS) assessed with a prospective cross‐over double‐blind assessment without medications (stimulation was randomly switched on or off). Secondary outcomes were motor UPDRS changes with unblinded assessments in off‐ and on‐medication states with and without stimulation, activities of daily living (ADL), anti‐PD medications, and dyskinesias. In double‐blind assessment, both STN and GPi DBS were significantly effective in improving the motor UPDRS scores (STN, P < 0.0001, 45.4%; GPi, P = 0.008, 20.0%) compared with off‐stimulation, regardless of the sequence of stimulation. In open assessment, both STN‐ and GPi‐DBS significantly improved the off‐medication motor UPDRS when compared with before surgery (STN, P < 0.001, 50.5%; GPi, P = 0.002, 35.6%). Dyskinesias and ADL were significantly improved in both groups. Anti‐PD medications were significantly reduced only in the STN group. Adverse events were more frequent in the STN group. These results confirm the long‐term efficacy of STN and GPi DBS in advanced PD. Although the surgical targets were not randomized, there was a trend to a better outcome of motor signs in the STN‐DBS patients and fewer adverse events in the GPi‐DBS group. © 2010 Movement Disorder Society     

High-frequency pallidal stimulation eliminates tic-related neuronal activity in a nonhuman primate model of Tourette syndrome

High-frequency deep brain stimulation targeting the output nucleus of the basal ganglia, the globus pallidus internus, has been suggested as a treatment modality for intractable Tourette syndrome and basal-ganglia-mediated motor tics. Recent studies on the modeling of motor tics induced by focal injections of bicuculline to the striatum, a putative model of Tourette syndrome, have shown that tics induce a widespread modulation within both segments of the globus pallidus. The purpose of this study was to investigate, using the bicuculline-induced Tourette syndrome model, whether and how high-frequency deep brain stimulation targeted to the globus pallidus internus could modulate tic-related activity in the pallidum. The perievent rate changes coinciding with tic expression under the on-stimulation and off-stimulation conditions were examined to determine the effect of high-frequency stimulation on pallidal activity. The results showed that the stimulation blocked tic-related phasic changes in the firing pattern of pallidal cells in parallel with a reduction of the peak amplitude of tic events in the electromyography record. This finding supports the premise that deep brain stimulation targeted to the globus pallidus internus could be a viable treatment option for Tourette syndrome, and the use of pallidal stimulation for motor tics warrants further study.     

Chronic bilateral pallidal stimulation in patients with generalized primary dystonia - multi-contact cathodal stimulation is superior to bipolar stimulation mode. Preliminary results

Background and purposePrimary generalized dystonia (PGD) is a medically refractory progressive disease of the brain causing near total handicap of affected patients. The aim of the study was to assess the efficacy and safety of bilateral pallidal stimulation in patients with PGD.Material and methodsThe study population is composed of 5 patients with PGD. The formal objective assessment included the Burke-Fahn-Marsden dystonia rating scale (BFMDRS). All stereotactic procedures were performed in general anaesthesia using a Leksell G stereotactic head frame without electrophysiological guidance. Immediately after insertion of deep brain stimulation (DBS) leads, the internal pulse generators (Itrel II or Soletra) were implanted subcutaneously in the chest wall or abdominal region.ResultsThere were no complications related to the stereotactic procedures. The hardware-related complications (two broken DBS leads) were replaced successfully. There were no infections or erosions of implanted hardware. It has been observed that in the long-term follow-up period primary set bipolar stimulation mode lost its benefit achieved previously. Various stimulation combinations were investigated. Monopolar cathodal or especially multi-contact cathodal stimulation was the most effective one. The efficacy of bilateral pallidal stimulation was proved by the objective validated BFMDRS at long-term follow-up.ConclusionsResponse to DBS may improve with the number of activated cathodal contacts within the globus pallidus internus.     

Evaluation of the efficacy of deep brain stimulation in the surgical treatment of cervical dystonia

ObjectiveDeep brain stimulation (DBS) of the globus pallidus internus (GPi) is a promising therapeutic option for patients with medically refractory dystonia. We present the results after 1 year of DBS of the GPi in 4 patients with cervical dystonia.Materials and methodsFour patients with medically refractory cervical dystonia who underwent stereotactic pallidal DBS surgery between June 2010 and November 2011 were included in this retrospective study. Preoperative and postoperative evaluations at 3, 6 and 12 months after surgery were performed using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS).ResultsThe 4 patients experienced a sustained improvement, with a mean TWSTRS reduction of 74.25%, at 12 months follow-up. Disability improved by 80.5% (mean) at 1 year follow-up. No stimulation-related side effects were reported.ConclusionPallidal DBS is a valid and effective second-line treatment for patients with cervical focal dystonia. Our results support its use in patients with an insufficient response to medical treatment.     

Sleep and impulsivity in Parkinson's disease

BackgroundImpulsive behavior and poor sleep are important non-motor features of Parkinson's disease (PD) that negatively impact the quality of life of patients and their families. Previous research suggests a higher level of sleep complaints in PD patients who demonstrate impulsive behaviors, but the nature of the sleep disturbances has yet to be comprehensively tested.MethodsConsecutive idiopathic PD patients (N = 143) completed the Minnesota Impulse Disorder Interview and a sleep questionnaire that assessed sleep efficiency, excessive daytime sleepiness, restless legs symptoms, snoring, dreams/nightmares, and nocturia. Patients were also given a Unified Parkinson's Disease Rating Scale motor examination and they completed cognitive testing.ResultsImpulsive PD patients endorsed more sleep complaints than non-impulsive PD patients. The group difference was primarily attributable to poor sleep efficiency (e.g., greater nocturnal awakenings), p < .01, and greater daytime sleepiness, p < .01, in the impulsive PD patients. Interestingly, restless legs symptoms were also greater in the impulsive PD patients, p < .05. The results could not be explained by medications or disease severity.ConclusionsPoor sleep efficiency, restless legs symptoms, and increased daytime sleepiness are associated with impulsivity in PD. Longitudinal studies are needed to determine whether sleep disturbances precede impulsivity in PD.     

Effect of Deep Brain Stimulation on Levodopa-Induced Dyskinesias and Striatal Oscillatory Local Field Potentials in a Rat Model of Parkinson's Disease

BackgroundIn Parkinson's disease (PD) dyskinesias appear after long-term dopaminergic treatment. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) or the globus pallidus internus (GPi) is a well-established treatment option for both PD symptoms and complications of medication.ObjectiveTo elucidate physiological mechanisms of the effect of DBS on levodopa-induced dyskinesias (LID) we investigated both DBS in the GPi and the centromedian-parafascicular complex (CM-Pf), which are part of an internal basal ganglia loop connecting with the dorsolateral striatum. In particular, we focused on changes of oscillatory activity in the dorsolateral striatum, which also presents the entrance region of the basal ganglia (BG).Methods6-Hydroxydopamine (6-OHDA) hemiparkinsonian (HP) rats and 6-OHDA lesioned HP rats with LID (HP-LID) were used to compare the effect of DBS in the entopeduncular nucleus (EPN, the equivalent to the human GPi) and the thalamic parafascicular nucleus (Pf, the equivalent of the human CM-Pf) on dyskinesias and neuronal oscillatory activity of selected frequency bands in the dorsolateral striatum on and off levodopa.ResultsIn HP-LID rats the relative beta and gamma power was lower, while relative theta power was higher as compared to HP rats. Chronic DBS of either the EPN or the Pf improved dyskinesia scores in HP-LID rats, and no differences in oscillatory activity were observed between groups.ConclusionsStimulation of the Pf has a specific impact on dyskinesias, which is similar to that found after EPN stimulation, and which is accompanied by changes of oscillatory activity.     

Cognitive and psychiatric outcome 3 years after globus pallidus pars interna or subthalamic nucleus deep brain stimulation for Parkinson's disease

BackgroundEffects on non-motor symptoms, mainly cognitive and psychiatric side effects, could influence the decision for either globus pallidus pars interna (GPi) or subthalamic nucleus (STN) deep brain stimulation (DBS) for patients with Parkinson's disease (PD).Objective1) To compare cognitive and psychiatric outcomes 3 years after GPi DBS versus STN DBS, and 2) to report on occurrence of suicidal ideation, psychiatric diagnoses, social functioning, and marital satisfaction 3 years after DBS.MethodsPatients were randomized to receive GPi DBS (n = 65) or STN DBS (n = 63). Standardized assessments were performed at baseline, 1 year, and 3 years. We used linear mixed model analyses to investigate between-group differences on the Mattis Dementia Rating Scale (MDRS), neuropsychological tests, and psychiatric questionnaires 3 years after DBS.ResultsEighty-seven patients (68%) completed at least one neuropsychological test after 3 years. No significant between-group differences were found on the MDRS (p = 0.61), neuropsychological tests (p-values between 0.17 and 0.87), and psychiatric questionnaires (p-values between 0.23 and 0.88) 3 years after DBS. The Mini International Neuropsychiatric Interview did not indicate a substantial number of psychiatric diagnoses after 3 years. Social functioning and marital satisfaction were comparable in both groups.ConclusionsThree years after GPi DBS and STN DBS no pronounced between-group differences on measures of cognitive and psychiatric functioning could be demonstrated. Overall, cognitive and psychiatric outcome 3 years after DBS do not provide a clear direction for clinicians when considering which of these two surgical targets to choose.     

Deep brain stimulation of globus pallidus internus for dystonia

Neuromodulation is the functional modification of neural structures through the use of electrical stimulation. Its most clinically applicable use is deep brain stimulation (DBS) of basal ganglia structures in Parkinson's disease (PD) and essential tremor (ET). More recently, it has been used as a means of treating dystonic movement disorders. The main target of DBS for dystonia is the posteroventral globus pallidus internus (GPi), although the thalamus has been used as an alternate target in a minority of cases. In comparison to the effects seen in PD, the improvement in dystonic postures appear to differ in several ways--delay of clinical benefit, higher voltage requirements, and varied stimulator settings. In this review, the authors discuss the clinical characteristics, pathophysiology, microelectrode recording (MER) signatures, optimal surgical targets, programming parameters and outcomes in dystonia.