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BACKGROUND: Patients with Parkinson's Disease (PD) who receive either asleep image-guided subthalamic nucleus deep brain stimulation (DBS) or the traditional awake technique have comparable motor outcomes. However, there are fewer studies regarding which technique should be chosen for globus pallidus internus (GPi) DBS. This systematic review and meta-analysis aims to compare the accuracy of lead placement and motor outcomes of asleep versus awake GPi DBS PD population. METHODS: We systematically searched PubMed, Embase, and Cochrane for studies comparing asleep vs. awake GPi DBS lead placement in patients with PD. Outcomes were spatial accuracy of lead placement, measured by radial error between intended and actual location, motor improvement measured using (UPDRS III), and postoperative stimulation parameters. Statistical analysis was performed with Review Manager 5.1.7. and OpenMeta [Analyst]. RESULTS: Three studies met inclusion criteria with a total of 247 patients. Asleep DBS was used to treat 192 (77.7 %) patients. Follow-up ranged from 6 to 48 months. Radial error was not statistically different between groups (MD -0.49 mm; 95 % CI -1.0 to 0.02; I2 = 86 %; p = 0.06), with a tendency for higher target accuracy with the asleep technique. There was no significant difference between groups in change on motor function, as measured by UPDRS III, from pre- to postoperative (MD 8.30 %; 95 % CI -4.78 to 21.37; I2 = 67 %, p = 0.2). There was a significant difference in postoperative stimulation voltage, with the asleep group requiring less voltage than the awake group (MD -0.27 V; 95 % CI -0.46 to - 0.08; I2 = 0 %; p = 0.006). CONCLUSION: Our meta-analysis indicates that asleep image-guided GPi DBS presents a statistical tendency suggesting superior target accuracy when compared with the awake standard technique. Differences in change in motor function were not statistically significant between groups.

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BACKGROUND: Hemidystonia (HD) is characterized by unilateral involuntary torsion movements and fixed postures of the limbs and face. It often develops after deleterious neuroplastic changes secondary to injuries to the brain. This condition usually responds poorly to medical treatment, and deep brain stimulation often yields unsatisfactory results. We propose this study based on encouraging results from case reports of patients with HD treated by ablative procedures in the subthalamic region. OBJECTIVE: To compare the efficacy of stereotactic-guided radiofrequency lesioning of the subthalamic area vs available medical treatment in patients suffering from acquired HD. METHODS: This is an open-label study in patients with secondary HD allocated according to their treatment choice, either surgical or medical treatment; both groups were followed for one year. Patients assigned in the surgical group underwent unilateral campotomy of Forel. The efficacy was assessed using the Unified Dystonia Rating Scale, Fahn-Marsden Dystonia Scale, Arm Dystonia Disability Scale, and SF-36 questionnaire scores. RESULTS: Patients in the surgical group experienced significant improvement in the Unified Dystonia Rating Scale, Fahn-Marsden Dystonia Scale, and Arm Dystonia Disability Scale (39%, 35%, and 15%, respectively) 1 year after the surgery, with positive reflex in quality-of-life measures, such as bodily pain and role-emotional process. Patients kept on medical treatment did not experience significant changes during the follow-up. No infections were recorded, and no neurological adverse events were associated with either intervention. CONCLUSION: The unilateral stereotaxy-guided ablation of Forel H1 and H2 fields significantly improved in patients with HD compared with optimized clinical treatment.

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BACKGROUND AND STUDY AIMS: Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is a highly effective therapy for primary generalized and focal dystonias, but therapeutic success is compromised by a nonresponder rate of up to 20%. Variability in electrode placement and in tissue stimulated inside the GPi may explain in part different outcomes among patients. Refinement of the target within the pallidal area could be helpful for surgery planning and clinical outcomes. The objective of this study was to discuss current and potential methodological (somatotopy, neuroimaging, and neurophysiology) aspects that might assist neurosurgical targeting of the GPi, aiming to treat generalized or focal dystonia. METHODS: We selected published studies by searching electronic databases and scanning the reference lists for articles that examined the anatomical and electrophysiologic aspects of the GPi in patients with idiopathic/inherited dystonia who underwent functional neurosurgical procedures. RESULTS: The sensorimotor sector of the GPi was the best target to treat dystonic symptoms, and was localized at its lateral posteroventral portion. The effective volume of tissue activated (VTA) to treat dystonia had a mean volume of 153 mm3 in the posterior GPi area. Initial tractography studies evaluated the close relation between the electrode localization and pallidothalamic tract to control dystonic symptoms.Regarding the somatotopy, the more ventral, lateral, and posterior areas of the GPi are associated with orofacial and cervical representation. In contrast, the more dorsal, medial, and anterior areas are associated with the lower limbs; between those areas, there is the representation of the upper limb. Excessive pallidal synchronization has a peak at the theta band of 3 to 8 Hz, which might be responsible for generating dystonic symptoms. CONCLUSIONS: Somatotopy assessment of posteroventral GPi contributes to target-specific GPi sectors related to segmental body symptoms. Tractography delineates GPi output pathways that might guide electrode implants, and electrophysiology might assist in pointing out areas of excessive theta synchronization. Finally, the identification of oscillatory electrophysiologic features that correlate with symptoms might enable closed-loop approaches in the future.

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Surgical approaches of internal globus pallidus (GPi) and ventral intermediate thalamic nucleus (Vim) have been used to treat different movement disorders. Three subjects with myoclonus-dystonia syndrome were surgically treated, one of them with GPi and Vim stimulation, while radiofrequency ablation of these structures was performed in the other 2 subjects. Surgical approach of both targets was performed simultaneously on each subject. Mean follow-up was of 33.3 months (22-48 months), the Unified Myoclonus Rating Scale action myoclonus (AM), functional tests (FT), patient questionnaire (PQ) sub-scores, and the Unified Dystonia Rating Scale (UDRS) were used during assessments. Improvement in all scales were seen 6 months after surgery (AM: 74%, FT: 60%, PQ: 63%, UDRS: 65%), and this benefit persisted throughout follow-up (AM: 61%, FT:62%, PQ: 65%, UDRS: 86%). No adverse events were noticed. Simultaneous unilateral procedures of GPi and Vim by either stimulation or ablation techniques improve both motor and functional scores in myoclonus-dystonia syndrome.

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Deep brain stimulation (DBS) is an established and effective treatment for several movement disorders and is being developed to treat a host of neuropsychiatric disorders including epilepsy, chronic pain, obsessive compulsive disorder, and depression. However, the neural mechanisms through which DBS produces therapeutic benefits, and in some cases unwanted side effects, in these disorders are only partially understood. Non-invasive neuroimaging techniques that can assess the neural effects of active stimulation are important for advancing our understanding of the neural basis of DBS therapy. Magnetoencephalography (MEG) is a safe, passive imaging modality with relatively high spatiotemporal resolution, which makes it a potentially powerful method for examining the cortical network effects of DBS. However, the degree to which magnetic artifacts produced by stimulation and the associated hardware can be suppressed from MEG data, and the comparability between signals measured during DBS-on and DBS-off conditions, have not been fully quantified. The present study used machine learning methods in conjunction with a visual perception task, which should be relatively unaffected by DBS, to quantify how well neural data can be salvaged from artifact contamination introduced by DBS and how comparable DBS-on and DBS-off data are after artifact removal. Machine learning also allowed us to determine whether the spatiotemporal pattern of neural activity recorded during stimulation are comparable to those recorded when stimulation is off. The spatiotemporal patterns of visually evoked neural fields could be accurately classified in all 8 patients with DBS implants during both DBS-on and DBS-off conditions and performed comparably across those two conditions. Further, the classification accuracy for classifiers trained on the spatiotemporal patterns evoked during DBS-on trials and applied to DBS-off trials, and vice versa, were similar to that of the classifiers trained and tested on either trial type, demonstrating the comparability of these patterns across conditions. Together, these results demonstrate the ability of MEG preprocessing techniques, like temporal signal space separation, to salvage neural data from recordings contaminated with DBS artifacts and validate MEG as a powerful tool to study the cortical consequences of DBS.

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Pallidal stimulation has been the usual surgical treatment for dystonia in the last decades. The continuous investigation of the physiopathology and the motor pathways involved leads to the search for complementary targets to improve results. The authors present the case of a 37-year-old woman who had suffered from idiopathic hemidystonia with hyperkinetic and hypokinetic movements for 11 years, and who was treated with deep brain stimulation. A brief literature review is also provided. The globus pallidus internus and the ventral intermediate/ventral oral posterior complex of the thalamus were stimulated separately and simultaneously for 3 months and compared using the Burke-Fahn-Marsden Dystonia Rating Scale and the Global Dystonia Severity Rating Scale, with a 3.5-year follow-up. The synergism of multiple-target stimulation resulted in a complete improvement of the mixed dystonic symptoms.

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OBJECTIVES: The objective of our paper is to show the partial decrease of therapeutic effect with battery exhaustion in a previously successfully treated patient with refractory Tourette's syndrome (TS). MATERIALS AND METHODS: We present a 47-year-old patient diagnosed with TS based on the TS Study Group Criteria and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. Surgery was considered based on refractoriness to conservative management. Presurgical evaluation included magnetic resonance imaging (MRI), positron emission tomography scan, and neuropsychologic, neurologic, and psychiatric tests utilizing Yale Brown Obsessive Compulsive Scale, Yale Global Tics Severity Scale, Hamilton Depression Rating Scale, Hamilton Anxiety Rating Scale, Global Assessment of Functioning Scale, and Mini-mental State Examination. Target coordinates were obtained from inversion recovery MRI. Quadripolar deep brain stimulation (DBS) electrodes were implanted bilaterally in the globus pallidus externus (GPe) and connected to the pulse generator in the same procedure. To determine the clinical response to DBS, the scores of the scales obtained preoperatively were compared with those obtained postoperatively. RESULTS: No surgical complications were detected and according to the clinical scales the patient experienced a marked improvement of his symptoms, although he never showed obsessive-compulsive disorder components of any type. The battery was exhausted after two years with the subsequent significant partial loss of therapeutic effect. CONCLUSIONS: GPe seems to be a highly promising target of DBS for the treatment of medically refractory TS. After battery exhaustion, the patient experienced a marked partial decrease in the therapeutic effect, which confirms the beneficial action of this method.

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Alterations in the basal ganglia-thalamocortical "motor" circuit activity, have been proposed to explain many features associated with hypokinetic and hyperkinetic movement disorders. We describe the firing pattern of the globus pallidus pars interna in a Parkinson disease's patient who developed Hemichorea-Ballismus subsequent to ipsilateral subthalamotomy, and compare findings to those from PD patients submitted to pallidotomy while in the OFF-medication state. Single units obtained from extracellular recordings were extracted and mean discharge frequency, interspike interval and coefficient of variation (defined as Tonicity Score) were computed. Discharge density histograms, analysis of distribution and spectral analysis were also performed. Mean firing frequency showed no significant difference between PD patients in the OFF state and the patient we report. However, a significant difference in tonicity was found for this patient characterized by a regular, non-bursting firing pattern. The findings indicate that in HB caused by lesions to STN in the parkinsonian state, GPi firing rates can be similar to and firing pattern more regular than those observed in GPi of PD patients OFF-medication with intact STN.

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