Deep brain stimulation for Parkinson's disease: how to select candidates for pallidal or subthalamic stimulation

Chronic deep brain stimulation therapy has the reversibility, selectivity and adjustability needed to achieve an adequate effect, so that it represents an ideal tool for functional neurosurgery designed to treat parkinsonian symptoms. Some kinds of chronic stimulation have become an alternative to lesion-making surgery, supported by the fact that high-frequency stimulation induces quite a small area of inactivity around the stimulating electrode compared with the lesions induced with a lesion-maker, and stimulation directed at a particular target exerts more specific effects on particular symptoms of Parkinson's disease (PD). Thus, whenever stimulation therapy is to be applied to patients, an effective stimulation target must be selected depending on the nature of the symptom to be improved. For example, ventral intermediate nucleus (VIM) thalamic stimulation is able to stop tremor completely, but has no appreciable effects on other symptoms. Bilateral globus pallidum interna (GPi) stimulation and subthalamic nucleus (STN) stimulation have been applied to reduce the pathological inhibitory effects on the thalamocortical circuit from the GPi and/or the substantia nigra pars reticular nucleus (SNr), which produces the final output of the basal ganglia circuits. However, there is still controversy about both the indications for and the role of GPi versus STN stimulation. This article presents a review of recent reports that describe follow-up results and double-blind studies on the signs for relief of each type of parkinsonian symptom, following GPi or STN stimulation. It also includes a discussion of how further research should be organized in order to identify whether GPi or STN stimulation exerts the greatest effect on particular kinds of parkinsonian symptoms.     

Deep brain stimulation in Parkinson's disease: bilateral implantation of globus pallidus and subthalamic nucleus

AIM: Deep brain stimulation (DBS) of subthalamic nucleus (STN) and of the pars interna of globus pallidus (GPi) is used to improve Parkinsonian symptoms and attenuate levodopa-induced motor complications in Parkinson's disease (PD). What are the physiological effect of DBS and the best anatomical structure to stimulate are still not completely clear. In this way we could evaluate the clinical effects of simultaneous stimulation of STN and GPi as well as the isolated stimulation of each target. METHODS: The stereotactic methods used to localise STN and GPi were based on non-telemetric ventriculography, with 3P Maranello or Leksell Stereotactic System. The effects of DBS have been assessed in 13 cases of PD, immediately after (30 minutes) the stimulation has turned on and during chronic stimulation (weeks or months). RESULTS: Most of the studies have been conducted on patients with STN implantation, and these studies reported relevant improvement in motor function and relatively low rate of complication. CONCLUSION: The large experience of ablative surgery associate with the DBS experience of some group worldwide indicate that GPi is a possible and very promising target for the management of Parkinsonian symptoms. Our patients demonstrate in acute and chronic evaluation, the best clinical results with contemporary activation of DBS in both targets.     

Deep brain stimulation for Parkinson's disease. A critical re-evaluation of STN versus GPi DBS

Deep brain stimulation (DBS) in the subthalamic nucleus (STN) and the internal segment of the globus pallidus (GPi) is increasingly being used for the treatment of advanced Parkinson's disease (PD). Although both targets have demonstrated clinical efficacy in the treatment of the cardinal motor signs of PD, the STN has gained greater popularity and is now considered the site of choice by most centers performing these procedures. This preference stems predominately from the belief that STN DBS provides greater improvement in reducing the motor manifestations of PD and allows a reduction in dopaminergic medication not permitted with GPi DBS. There are, however, a number of issues that must be considered before abandoning GPi in favor of STN as the surgical target of choice for DBS. The maximal benefit reported for GPi stimulation is not significantly different than that reported for the STN, 67 versus 71%, and while reductions in medication are required with STN stimulation to avoid inducing dyskinesia, GPi stimulation may directly suppress dyskinesia obviating any need to reduce medication. As such, many centers may not attempt to reduce antiparkinsonian medication with GPi DBS. In addition, there are significantly more reports of changes in mood, behavior and a higher incidence of adverse events reported for STN stimulation. Most studies of DBS are nonrandomized, assessment protocols are not standardized, and lead locations are not reported. Thus, before drawing conclusions regarding the optimal site for DBS for advanced PD we must take a critical eye to the present data and address the outstanding questions that remain with well-designed clinical trials that evaluate motor, nonmotor and adverse events and address the above clinical variables by randomizing patients, using standardized methods of assessment and defining the lead location.     

Spinal accessory neuropathy after deep brain stimulation for Parkinson's disease

We report a man with Parkinson's disease who developed right spinal accessory neuropathy after right subthalamic nucleus deep brain stimulator and infraclavicular pulse generator implantation. He complained of right shoulder pain and weakness in the post-operative period. He was subsequently diagnosed with a right spinal accessory nerve injury, confirmed by neuromuscular electrodiagnostic studies - electromyography (EMG) and nerve conduction (NC) -, possibly caused by a stretch injury to the nerve at the time of creation of the subcutaneous tunnel for placement of the extension lead of the deep brain stimulator system. However, he had near complete clinical resolution of the spinal accessory neuropathy within nine months after surgery. As a result of this complication, we now map the spinal accessory nerve electrophysiologically during deep brain stimulation surgery.     

Deep brain stimulation for parkinson's disease: correlation between intraoperative subthalamic nucleus neurophysiology and most effective contacts

Though intraoperative neurophysiology is essential to precisely define the definitive target, little is known regarding its predictive value in defining the most effective contact for chronic deep brain stimulation. In this retrospective study, we reviewed the correlation between intraoperative neurophysiology and contacts selected for chronic stimulation. Twenty consecutive patients implanted for subthalamic nucleus (STN) stimulation were reviewed. There was no significant correlation between the electrophysiologically defined STN and the most effective contact for chronic stimulation at 3 months or at 6 months. Furthermore, there was a discrepancy between the most effective contact for rigidity versus akinesia or tremor at 3 months. Interestingly, at 3 months, the same electrode contact was maximally efficient for rigidity, akinesia and tremor in only 13 of the 39 cases. This lack of correlation did not affect the global improvement.     

Deep brain stimulation for dystonia

Opinion statement Dystonia refers to movement disorders characterized by sustained muscle contractions that produce abnormal postures, twisting movements, and other abnormal involuntary movements. A spectrum of etiologies underlies the various dystonia syndromes, ranging from genetic conditions to brain injury. First-line therapy for dystonia consists of pharmacologic agents of several classes and, particularly for focal dystonia, chemodenervation therapy with botulinum toxin. Many patients with dystonia realize an inadequate response to those treatments, and for such patients whose symptoms are sufficiently troublesome, surgical treatment can be used to reduce symptoms and improve function. Previously, the ablative procedures of thalamotomy and pallidotomy were used, in which a permanent destructive lesion was made in the motor territory of the thalamus or the globus pallidus. More recently, the device-based therapy of deep brain stimulation (DBS) has emerged as the preferred surgical treatment for dystonia and other movement disorders for most patients who require operative intervention. DBS uses a surgically implanted brain lead connected to an implanted neurostimulator to deliver chronic, high-frequency electrical stimulation to one of several deep nuclei. For dystonia, stimulation directed at the globus pallidus internus has been the most thoroughly studied to date. Advantages of DBS include its relatively non-destructive nature, its adjustability and reversibility, and its capacity to be used bilaterally in a safe manner. Use of DBS to treat dystonia is a rapidly evolving area, and preliminary evidence suggests that primary dystonia linked to genetic mutation, other primary dystonias, and tardive dystonic syndromes respond most dramatically to treatment with DBS, whereas secondary dystonia tends to be less responsive.     

双侧丘脑底核脑深部刺激治疗帕金森病

目的 探讨双侧脑深部刺激(Deep brain stimulation，DBS)系统治疗帕金森病(Parkinson’s disease，PD)的手术方法和效果。方法 对13例具有双侧症状的帕金森病进行同期双侧丘脑底核双通道DBS治疗。术中采用磁共振扫描结合微电极记录技术进行靶点定位。术后用UPDRS运动评分评价刺激效果。结果 13例PD术后随访3月—3年，平均6．3月。脉冲发生器开启时，在“关”状态下，UPDRS运动评分症状平均改善率62．3％，其中对左旋多巴类药物反应敏感改善率达75．5％；在“开”状态下，UPDRS运动评分症状改善率24．2％。未发现任何并发症。结论 双侧丘脑底核脑深部刺激治疗可明显改善PD患运动功能。     

Progression of Parkinson's disease following thalamic deep brain stimulation for tremor

We assessed the long-term effect of thalamic deep brain stimulation (DBS) on motor symptoms and progression of Parkinson's disease (PD) in PD patients treated for resting and postural/action tremor. Thalamic DBS was performed in 17 patients with treatment-resistant resting and postural/action tremor. Nine patients were available for follow-up examination a mean of 5.5 years after surgery. Three had tremor-dominant PD. DBS produced marked improvement in resting and postural/action tremor in target upper extremity in all 9 patients, which persisted unchanged at the time of the last follow-up visit 5.5 years after surgery. PD severity with DBS 'on' and 'off' 1 year after surgery was compared to PD severity at the last follow-up visit using UPDRS (Unified Parkinson's Disease Rating Scale) III motor scores and individual motor item subscores. Patients were tested while on medication. There was no significant worsening of tremor, rigidity, speech, postural stability, gait, or axial bradykinesia with DBS either on or off at the last follow-up visit compared to the 12-month visit. UPDRS III motor scores were unchanged. However, global assessment of PD progression and increased mean L-dopa dose and L-dopa equivalent daily dose at the time of last follow-up visit indicated that a progression of PD had occurred.     

MRI indirect stereotactic targeting for deep brain stimulation in Parkinson's disease

AIM: Stereotactic localisation of brain targets for functional neurosurgery might be obtained with different neuroimaging sources. Magnetic resonance (MR) might be of particular interest for its high definition of the various brain structures; unfortunately, magnetic field distortion and inaccuracy in imaging reproduction constrain the use of MRI in stereotactic surgery. METHODS: We present an experimental work devoted to the utilization of MRI in the targeting of the subthalamic nucleus for deep brain stimulation (DBS) in Parkinsonian patients. RESULTS: Experimental data were obtained after PVC phantom and fixed human brain measurements of the stereotactic coordinates of specific basal ganglia structures. Intrinsic and external sources of error and imaging distortion have been carefully corrected. Afterwards, 36 patients, operated for DBS in the subthalamus for Parkinson's disease (PD), have been investigated. MRI targeting proved to be clinically successful; comparing anatomical and neurophysiological findings, MRI targeting scattered from the neurophysiological targeting in a minority of cases. CONCLUSION: MRI targeting proved to be reliable for functional stereotactic surgery, pending careful and adequate quality control of the distortion and of the sources of error.