Temporal changes in movement time during the switch of the stimulators in Parkinson's disease patients treated by subthalamic nucleus stimulation

OBJECTIVE: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a very effective therapy for the advanced phase of Parkinson's disease (PD). The functional inhibition of this nucleus is responsible for a significant improvement of cardinal motor symptoms of PD. The aim of the study was the assessment of the effectiveness of STN DBS on bradykinesia by the analysis of movement time (MT) in 2 conditions: with the stimulators turned on ('stim-on') or off ('stim-off'). METHODS: After pharmacological wash-out, 10 patients submitted to bilateral STN DBS were studied with an MT analyser in 3 phases: stim-on, stim-off and stim-on again, in order to establish the time course of MT lengthening, the posteffect duration and the latency of the effect of STN DBS. MT data were then compared with the UPDRS motor scores. RESULTS: After turning off the stimulators, MT progressively increases, reaching a plateau after about 30 min, which then lasts for the subsequent observation time (2 h). A significant elongation is achieved after the first 5 min. Upon pulse generator activation, MT shows a dramatic shortening, already significant after 2 min. Moreover, we observed a significant correlation between MT and the severity of PD, higher with bradykinesia than with rigidity or tremor. CONCLUSION: Our findings show a relevant effect of STN DBS on MT, a parameter strongly related to bradykinesia. This study confirms the effectiveness of STN inhibition on the whole parkinsonian triad, suggesting that this target can be considered a proper choice for the surgical treatment of advanced PD.     

Effects of deep brain stimulation of the subthalamic nucleus on sleep architecture in parkinsonian patients

Patients affected by Parkinson's disease (PD) often complain of disturbed sleep resulting from nighttime motor disabilities such as nocturnal akinesia, tremor and rigidity, motor behaviour during REM sleep or periodic leg movements (PLM) during sleep. Sleep may also be affected by dopaminergic and anticholinergic drugs or coexisting depressive syndrome. Deep brain stimulation (DBS) of subthalamic nucleus (STN) effectively reduces PD motor disability. The aim of this study is to evaluate the sleep architecture modifications after STN DBS. We assessed five patients (two men and three women, mean age 63.8+/-3.3 years, with a mean history of PD of 13.8+/-4.9 years) who underwent STN DBS. The mean levodopa equivalent dosage (LED) was 1010+/-318 mg before surgery and 116+/-93 mg 3 months after surgery. Polysomnography (PSG) with audiovisual recordings was performed on two separate nights, the first assessment in the week before surgery and the second 3 months after surgery. Three months after surgery, PSG showed an increase in total sleep time, in the longest period of uninterrupted sleep, and in the percentage of stage 3-4 NREM sleep, while there was a reduction of wakefulness after sleep onset. PLM, apnea-hyopnea index and REM sleep behaviour disorder were unaffected by STN DBS. STN DBS seems to be an effective therapeutic option for the treatment of advanced Parkinson's disease because it improves the cardinal symptoms and also seems to improve sleep architecture.     

双侧丘脑底核脑深部刺激术治疗帕金森病13例报告

目的 探讨双侧丘脑底核（STN）脑深部刺激术（DBS）治疗帕金森病的临床经验。方法 从2002年到2005年共完成了13例帕金森病的双侧丘脑底核DBS，根据STN解剖学定位，靶点的理论坐标值是X=11-13mm，Y=0-2mm，Z=0-4mm，通过立体定向技术在双侧丘脑底核植入刺激电极，并于锁骨下方植入脑深部电刺激器。结果 随访时间为6个月到3年，3例震颤为主病人的症状完全缓解，即震颤完全消失；僵直和运动迟缓为主要症状者的症状缓解程度达90％以上，其中以四肢肌肉僵直的效果较好，运动迟缓也有明显缓解，但是有1例病人双侧肢运动协调性差。所有患者植物神经功能症状有较明显改善，如便秘、流涎、出汗和浮肿等均有改善。结论 DBS治疗帕金森病，是帕金森病治疗的一个里程碑似的进步。它可以明显地缓解帕金森病的主要症状和体征，对运动迟缓、僵直和震颤等均有较理想的效果。     

刺激术和毁损术在双侧立体定向手术治疗帕金森病中的比较

目的比较脑深部刺激术和毁损术在双侧立体定向手术治疗帕金森病中的优缺点。方法69例帕金森病病人进行了双侧手术治疗,其中同期双侧丘脑底核(STN)脑深部刺激术(DBS)11例,同期一侧苍白球腹后部毁损术(PVP),另一侧STNDBS3例,分期一侧PVP或腹中间核(Vim)毁损术、另一侧STN或VimDBS9例;分期双侧PVP或Vim毁损术41例,同期双侧PVP5例。平均随访9.3个月。结果UPDRS评分显示刺激术和毁损术均能显著改善对侧肢体震颤、僵硬和运动迟缓症状,双侧刺激术还能改善步态和姿势症状,但双侧毁损术可加重语言、吞咽及流涎等症状,并发症较高。结论双侧DBS是具有双侧症状的帕金森病病人手术治疗的最佳术式,双侧毁损术并发症较高,应严格慎重采用。     

Improvement in a quantitative measure of bradykinesia after microelectrode recording in patients with Parkinson's disease during deep brain stimulation surgery.

It is widely accepted that patients with Parkinson's disease experience immediate but temporary improvement in motor signs after surgical implantation of subthalamic nucleus (STN) deep brain stimulating electrodes before the electrodes are activated, although this has never been formally studied. Based on anecdotal observations that limb mobility improved just after microelectrode recording (MER) during deep brain stimulation (DBS) procedures, we designed a prospective study to measure upper extremity bradykinesia using a quantitative measure of angular velocity. Measurements were made pre- and post-MER and during intraoperative DBS. Analysis of 98 STN DBS procedures performed on 61 patients showed that MER did not create adverse clinical symptoms despite concerns that MER increases morbidity. Quantitative upper extremity bradykinesia improved after MER alone, and further improvement was seen during intraoperative DBS. Electrophysiological data from each case were then compared to the improvement in bradykinesia post-MER alone and a significant correlation was found between the improvement in arm bradykinesia, the number of passes through the STN with somatosensory driving, and also with the number of arm cells with somatosensory driving in the STN, but not with total number of passes, total number of passes through the STN, or total number of cells with somatosensory driving in the STN. This study demonstrates that there is a significant improvement in upper extremity bradykinesia just after MER, before inserting or activating the DBS electrode in patients with Parkinson's disease who undergo STN DBS.     

Deep brain stimulation for Parkinson's disease

Deep brain stimulation (DBS) is making a major impact in patients with advanced Parkinson's disease who continue to be disabled despite the best available medical therapy. Stimulation of the internal segment of the globus pallidus (GPi) or the subthalamic nucleus (STN) can improve tremor, rigidity, bradykinesia and gait disturbances in Parkinson's disease and improve the day-to-day activities of patients with these disabling symptoms. While the mechanism of action of DBS remains poorly understood, the success of technique in the treatment of movement disorders is bringing into question traditional concepts of the organization and of the basal ganglia and spearheading a re-examination of the nature and function of brain areas involved in the control of movement. Future developments in this rapidly advancing area will include the elucidation of the mechanism of action of DBS and technical advances in surgical techniques, in electrode design and in choosing better stimulation parameters. These advances will improve the scope and effectiveness of DBS and expand its clinical indications.     

Stimulation of the subthalamic nucleus in a patient with Parkinson disease and essential tremor

BACKGROUND: The preferred surgical target for the treatment of Parkinson disease (PD) is either the internal globus pallidus or the subthalamic nucleus (STN); the target for treatment of essential tremor (ET) is the thalamic subnucleus ventralis intermedius (Vim). Some patients with PD have coexistent ET, and the identification of a single surgical target to treat both parkinsonian motor symptoms and ET would be of practical importance. OBJECTIVE: To describe the use of the STN target in deep brain stimulator (DBS) surgery to treat PD motor symptoms and the action-postural tremor of ET. DESIGN: Case report. PATIENT: A 62-year-old man had a greater than 30-year history of action-postural tremor in both hands, well controlled with beta-blockers for more than 20 years. He developed resting tremor, bradykinesia, and rigidity on his right side that progressed to his left side during the past 10 years. Dopaminergic medication improved his rigidity and bradykinesia, with only mild improvement of his resting tremor and no effect on his action-postural tremor. INTERVENTIONS: Left pallidotomy followed by placement of a left DBS in the Vim and subsequent placement of a right STN DBS. MAIN OUTCOME MEASURES: Control of symptoms of PD and ET. RESULTS: The left pallidotomy controlled the patient's parkinsonian motor symptoms on the right side of his body, but did not affect the action-postural component of his tremor. The symptoms on the left side of the body, including both an action-postural and a resting tremor (as well as the rigidity and bradykinesia), improved after placement of a single right STN DBS. CONCLUSION: Placement of an STN DBS should be considered as the procedure of choice for surgical treatment of patients with a combination of PD and ET.     

The impact on Parkinson's disease of electrical parameter settings in STN stimulation

BACKGROUND: The main advantage of deep brain stimulation (DBS) in the treatment of PD is that the electrical settings can be adjusted to optimize benefits and minimize adverse effects. The main objective of this study was to discover how varying these electrical parameters impacted on parkinsonian motor signs. METHODS: Twelve patients with PD with chronic bilateral subthalamic nucleus (STN) stimulation were selected. The authors evaluated the effects of a variation in the voltages, frequencies, and pulse widths on tremor, bradykinesia, and rigidity using two different paradigms: one in which the total electrical energy delivered was held constant, and one in which this was varied. Up to 26 parameter conditions were tested under double blind randomized conditions. RESULTS: Voltages >or=3 V and frequencies >or=130 Hz led to the greatest improvement in all three parkinsonian signs. A rate of 5 Hz significantly worsened akinesia. The combination of the highest voltage with the narrowest pulse width was most effective. CONCLUSIONS: This study confirms that the most beneficial effects induced by STN stimulation are obtained at high frequencies and that voltage is the most critical factor to obtain adequate alteration in STN activity. The mechanisms by which STN DBS improves parkinsonism remain speculative.     

Bilateral subthalamic nucleus stimulation for Parkinson's disease

High frequency stimulation of the subthalamic nucleus (STN) is known to ameliorate the signs and symptoms of advanced Parkinson's disease. AIM: We studied the effect of high frequency STN stimulation in 23 patients. METHOD: Twenty-three patients suffering from severe Parkinson's disease (Stages III-V on Hoehn and Yahr scale) and, particularly bradykinesia, rigidity, and levodopa-induced dyskinesias underwent bilateral implantation of electrodes in the STN. Preoperative and postoperative assessments of these patients at 1, 3, 6 and 12 months follow-up, in "on" and "off" drug conditions, was carried out using Unified Parkinson's Disease Rating Scale, Hoehn and Yahr staging, England activities of daily living score and video recordings. RESULTS: After one year of electrical stimulation of the STN, the patients' scores for activities of daily living and motor examination scores (Unified Parkinson's Disease Rating Scale parts II and III) off medication improved by 62% and 61% respectively (p<0.0005). The subscores for the akinesia, rigidity, tremor and gait also improved. (p<0.0005). The average levodopa dose decreased from 813 mg to 359 mg. The cognitive functions remained unchanged. Two patients developed device-related complications and two patients experienced abnormal weight gain. CONCLUSION: Bilateral subthalamic nucleus stimulation is an effective treatment for advanced Parkinson's disease. It reduces the severity of "off" phase symptoms, improves the axial symptoms and reduces levodopa requirements. The reduction in the levodopa dose is useful in controlling drug-induced dyskinesias.     

Electric field and stimulating influence generated by deep brain stimulation of the subthalamic nucleus.

OBJECTIVE: The goal of this project was to develop a quantitative understanding of the volume of axonal tissue directly activated by deep brain stimulation (DBS) of the subthalamic nucleus (STN). METHODS: The 3-dimensionally inhomogeneous and anisotropic tissue medium surrounding DBS electrodes complicates our understanding of the electric field and tissue response generated by the stimulation. We developed finite element computer models to address the effects of DBS in a homogeneous isotropic medium, and a medium with tissue conductivity properties derived from human diffusion tensor magnetic resonance data. The second difference of the potential distribution generated in the tissue medium was used as a predictor of the volume of tissue supra-threshold for axonal activation. RESULTS: The model predicts that clinically effective stimulation parameters (-3 V; 0.1 ms; 150 Hz) result in activation of large diameter (5.7 microm) myelinated axons over a volume that spreads outside the borders of the STN. The shape of the activation volume was dependent on the strong dorsal-ventral anisotropy of the internal capsule, and the moderate anterior-posterior anisotropy of the region around zona incerta. CONCLUSIONS: Small deviations ( approximately 1 mm) in the electrode position within STN can substantially alter the shape of the activation volume as well as its spread to neighboring structures. SIGNIFICANCE: STN DBS represents an effective treatment for medically refractory movement disorders such as Parkinson's disease. However, stimulation induced side effects such as tetanic muscle contraction, speech disturbance and ocular deviation are not uncommon. Quantitative characterization of the spread of stimulation will aid in the development of techniques to maximize the efficacy of DBS.     

Deep brain stimulation in the management of Parkinson's disease

Deep brain stimulation (DBS) is a neurosurgical treatment of Parkinson's disease and other movement disorders. This surgical technique is applied to three brain targets: the ventral intermediate nucleus of the thalamus (Vim), the globus pallidus internus (Gpi) and the subthalamic nucleus (STN). Vim DBS improves contralateral parkinsonian tremor. STN and GPi DBS improve contralateral bradykinesia, rigidity, parkinsonian tremor and also levodopa-induced dyskinesia. There is little comparative data between bilateral STN and bilateral GPi procedures but the improvement with bilateral STN DBS seems more pronounced than with bilateral GPi DBS. Moreover, only STN BDS allows a significant decrease of antiparkinsonian medication. The other advantage of STN over GPi DBS is the lower consumption of current. The DBS procedure contrary to ablative surgery has the unique advantage of reversibility and adjustability over time. Patients with no behavioral, mood and cognitive impairments benefit the most from bilateral STN DBS. The stimulation-induced adverse effects related to DBS are reversible and adjustable. More specific adverse effects related do hardware are: disconnection, lead breaking, erosion or infection. The disadvantage of DBS is a relatively high cost. The setting of stimulation parameters to achieve the best clinical result may be very time-consuming. Most authors agree that DBS is a safer and more favorable procedure than ablative surgery.     

Pyramidal tract activation due to subthalamic deep brain stimulation in Parkinson's disease

Background: Subthalamic deep brain stimulation (STN‐DBS) is an effective treatment for Parkinson's disease (PD), but can have side effects caused by stimulus spread to structures outside the target volume such as the pyramidal tract. Objectives: To assess the relevance of pyramidal tract activation with STN‐DBS in PD. Methods: In a multimodal, blinded study in 20 STN‐DBS patients, we measured stimulation thresholds for evoking electromyographic activity in orbicularis oris and first dorsal interosseous muscles at each of 150 electrode sites. We also modeled the electric field spread and calculated its overlap with the estimated anatomical location of corticospinal and corticobulbar tracts from primary motor cortex using 3 Tesla MRI probabilistic tractography. Results: Mean resting motor thresholds were significantly lower for the contralateral orbicularis oris (3.5 ± 1.0 mA) compared with ipsilaterally (4.1 ± 1.1 mA) and with the contralateral first dorsal interosseous (4.0 ± 1.2 mA). The modeled volumes of corticobulbar and corticospinal tract activated correlated inversely with the resting motor threshold of the contralateral orbicularis oris and first dorsal interosseous, respectively. Active motor thresholds were significantly lower compared with resting motor thresholds by around 30% to 35% and correlated with the clinically used stimulation amplitude. Backward multiple regression in 12 individuals with a “lateral‐type” speech showed that stimulation amplitude, levodopa equivalent dose reduction postsurgery, preoperative speech intelligibility, and first dorsal interosseous resting motor thresholds explained 79.9% of the variance in postoperative speech intelligibility. Conclusions: Direct pyramidal tract activation can occur at stimulation thresholds that are within the range used in clinical routine. This spread of current compromises increase in stimulation strengths and is related to the development of side effects such as speech disturbances with chronic stimulation. © 2017 International Parkinson and Movement Disorder Society     

Localization of motor and verbal fluency effects in subthalamic DBS for Parkinson's disease

IntroductionSubthalamic nucleus deep brain stimulation (STN DBS) improves cardinal motor symptoms of Parkinson's disease (PD) but can worsen verbal fluency (VF). An optimal site of stimulation for overall motor improvement has been previously identified using an atlas-independent, fully individualized, field-modeling approach. This study examines if cardinal motor components (bradykinesia, tremor, and rigidity) share this identified optimal improvement site and if there is co-localization with a site that worsens VF.MethodsAn atlas-independent, field-modeling approach was used to identify sites of maximal STN DBS effect on overall and cardinal motor symptoms and VF in 60 patients. Anatomic coordinates were referenced to the STN midpoint. Symptom severity was assessed with the MDS-UPDRS part III and established VF scales.ResultsSites for improved bradykinesia and rigidity co-localized with each other and the overall part III site (0.09 mm lateral, 0.93 mm posterior, 1.75 mm dorsal). The optimal site for tremor was posterior to this site (0.10 mm lateral, 1.40 mm posterior, 1.93 mm dorsal). Semantic and phonemic VF sites were indistinguishable and co-localized medial to the motor sites (0.32 mm medial, 1.18 mm posterior, 1.74 mm dorsal).ConclusionThis study identifies statistically distinct, maximally effective stimulation sites for tremor improvement, VF worsening, and overall and other cardinal motor improvements in STN DBS. Current electrode sizes and voltage settings stimulate all of these sites simultaneously. However, future targeted lead placement and focused directional stimulation may avoid VF worsening while maintaining motor improvements in STN DBS.     

双侧丘脑底核脑深部电刺激治疗帕金森病

目的 应用双侧丘脑底核脑深部电刺激（DBS）治疗难治性帕金森病（PD），并对其疗效作出评价。方法 对7例帕金森病患者采用磁共振导向立体定向及术中电生理验证方法，将刺激电极分别植入丘脑底核，采用同期或分期植入刺激发生器。术后1周用程控计算机在体外调速刺激参数，以达到最佳疗效。结果 6例患者术后均获得了显著的疗效。震颤完全消失，肌强直、步态、姿障碍以及药物所致的并发症明显,面时多巴胺类药物用量明显减少，1例曾接爱双侧丘脑腹中间核及一侧苍白球毁损后的患者只得到了轻度改善。结论 DBS法治疗中晚期PD，具有安全，副作用可逆转的优点，且可根据患者的不同状况及病情发展调节刺激参数达到最佳症状控制，完全控制震颤，明显改善肌张力障碍、步态、资势等运动障碍及药物所致的并发症，另外多巴胺类药物的用量也明显减少。     

Relationship of clinical efficacy to postmortem-determined anatomic subthalamic stimulation in Parkinson syndrome

OBJECTIVE/BACKGROUND: Patients with medically refractory Parkinson's disease (PD) obtain significant clinical benefit from subthalamic nucleus (STN) stimulation. The degree to which a successful outcome relates to the anatomic location of the stimulating electrode has not yet been clearly established. Many studies have attempted to correlate the clinical result with the electrode location using postoperative magnetic resonance imaging (MRI) and there have been a few that used autopsy-determined locations. In this report, we describe long-term clinical follow-up in a patient with autopsy-determined electrode tip anatomic location. METHODS: A 67-year-old patient with a 27-year history of idiopathic PD complicated by disabling motor fluctuations and dopaminergic dyskinesias underwent bilateral STN deep brain stimulation (DBS). He was prospectively followed in a long-term clinical protocol until his death 40 months after electrode placement. Postoperative magnetic resonance (MR) imaging and postmortem studies of this patient's brain were performed to localize DBS tip locations. RESULTS: STN stimulation produced improvement of the patient's motor fluctuations, dyskinesias and clinical motor performance, especially appendicular tremors, rigidity and bradykinesia. MRI showed the electrode tips to be within 2 mm of the intended target. Postmortem brain analysis identified the right DBS tip location at the dorsomedial edge of the STN, with the left electrode in the vicinity (but not within) the STN. Chronic DBS elicited minor reactive changes were confined to the immediate vicinity of the electrode tracks. The pathological analysis demonstrated numerous cortical Lewy bodies and degenerative encephalopathy, establishing the diagnosis of transitional type diffuse Lewy body disease (DLBD) rather than simple PD. CONCLUSION: This patient obtained clinical benefit from STN stimulation typical of that seen for most PD patients. Both the MR analysis and the autopsy demonstrated electrode placement at or outside the boundaries of the STN, suggesting that that clinical efficacy may not depend on electrode location within the central region of the STN.     

External pallidal stimulation improves parkinsonian motor signs and modulates neuronal activity throughout the basal ganglia thalamic network

Deep brain stimulation (DBS) of the internal segment of the globus pallidus (GPi) and the subthalamic nucleus (STN) are effective for the treatment of advanced Parkinson's disease (PD). We have shown previously that DBS of the external segment of the globus pallidus (GPe) is associated with improvements in parkinsonian motor signs; however, the mechanism of this effect is not known. In this study, we extend our findings on the effect of STN and GPi DBS on neuronal activity in the basal ganglia thalamic network to include GPe DBS using the 1-methyl-4-phenyl-1.2.3.6-tetrahydropyridine (MPTP) monkey model. Stimulation parameters that improved bradykinesia were associated with changes in the pattern and mean discharge rate of neuronal activity in the GPi, STN, and the pallidal [ventralis lateralis pars oralis (VLo) and ventralis anterior (VA)] and cerebellar [ventralis lateralis posterior pars oralis (VPLo)] receiving areas of the motor thalamus. Population post-stimulation time histograms revealed a complex pattern of stimulation-related inhibition and excitation for the GPi and VA/VLo, with a more consistent pattern of inhibition in STN and excitation in VPLo. Mean discharge rate was reduced in the GPi and STN and increased in the VPLo. Effective GPe DBS also reduced bursting in the STN and GPi. These data support the hypothesis that therapeutic DBS activates output from the stimulated structure and changes the temporal pattern of neuronal activity throughout the basal ganglia thalamic network and provide further support for GPe as a potential therapeutic target for DBS in the treatment of PD.     

Subthalamic nucleus stimulation affects a frontotemporal network: a PET study

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has become an effective strategy in the treatment of motor symptoms in advanced Parkinson's disease. However, clinical studies have shown that DBS can affect verbal fluency. Seven Parkinson's disease patients with bilateral DBS of the STN were studied with positron emission tomography (PET) to investigate the effects of STN stimulation on regional cerebral blood flow during a verbal fluency task. Activation of the right orbitofrontal cortex and verbal fluency-associated activation within a left-sided frontotemporal network were decreased during STN stimulation compared with the OFF state. Our results offer an explanation for the commonest neuropsychological side effect of STN stimulation and show that STN stimulation affects a frontotemporal network during a fluency task.     

脑深部刺激电极埋置术治疗帕金森病疗效研究

目的 探讨脑深部刺激电极埋置术治疗帕金森病的疗效及其作用机制。方法 对32例帕金森病患者应用微电极导向立体定向技术,于丘脑底核埋置体外可控性脑深部刺激电极,对其疗效和预后进行随访。结果患者术后僵硬、震颤和运动迟缓等症状明显缓解,术前、术后统一帕金森病评分量表(unified Parkinson's disease ratingscale,UPDRS)运动评分和日常生活能力(activities of daily living,ADL)评分有显著性差异(P<0.01),部分患者由药物引起的开-关现象也有明显缓解;协同服用的多巴胺类药物的用量也有不同程度的减少。所有患者术中及术后均无严重的并发症,术后随访疗效肯定。结论 丘脑底核放置深部脑刺激电极,能明显改善帕金森病患者的临床症状,提高手术的安全性,并发症少。     

Local field potential beta activity in the subthalamic nucleus of patients with Parkinson's disease is associated with improvements in bradykinesia after dopamine and deep brain stimulation

Parkinson's disease is treated pharmacologically with dopamine replacement medication and, more recently, by stimulating basal-ganglia nuclei such as the subthalamic nucleus (STN). Depth recordings after this procedure have revealed excessive activity at frequencies between 8 and 35 Hz ([Brown et al., 2001], [Kuhn et al., 2004] and [Priori et al., 2004]) that are reduced by dopamine therapy in tandem with improvements in bradykinesia/rigidity, but not tremor (Kuhn et al., 2006). It has also been shown that improvements in motor symptoms after dopamine correlate with single unit activity in the beta range (Weinberger et al., 2006). We recorded local field potentials (LFPs) from the subthalamic nucleus of patients with Parkinson's disease (PD) after surgery to implant deep brain stimulating electrodes while they were on and off dopaminergic medication. As well as replicating Kuhn et al., using the same patients we were able to extend Weinberger et al. to show that LFP beta oscillatory activity correlated with the degree of improvement in bradykinesia/rigidity, but not tremor, after dopamine medication. We also found that the power of beta oscillatory activity uniquely predicted improvements in bradykinesia/rigidity, but again not tremor, after stimulation of the STN in a regression analysis. However improvements after STN stimulation related inversely to beta power, possibly reflecting the accuracy of the electrode placement and/or the limits of STN stimulation in patients with the greatest levels of beta oscillatory activity.     

Effect of short and long term STN stimulation periods on parkinsonian signs

Currently, no study of subthalamic nucleus (STN) stimulation has compared continuous stimulation with a period of short‐term stimulation, which is frequently employed in the clinic and in research studies. Therefore, this study examined the effects of STN stimulation over 90 min (short) and greater than 3 months (long) on the cardinal signs of Parkinson's disease. The 90 min time period immediately followed a 12 hour withdrawal from both STN stimulation and medication. Ten PD patients who received STN stimulation were studied. Bradykinesia, rigidity, and tremor were evaluated using the UPDRS and motor control measures which included peak velocity (bradykinesia), work (rigidity), and amplitude (tremor). Results showed no difference between 90 min and greater than 3 months of STN stimulation for the UPDRS or motor control measures. This finding confirms that the treatment efficacy that is derived from a relatively short time course of stimulation generalizes to longer time periods of high frequency STN stimulation that patients experience in their daily lives. As such, it is reasonable to evaluate the effect of DBS after 90 min of stimulation in clinical trials and research studies. © 2008 Movement Disorder Society