Efficacy and safety of combined deep brain stimulation with capsulotomy for comorbid motor and psychiatric symptoms in Tourette's syndrome: Experience and evidence.

OBJECTIVES: To evaluate the efficacy and safety of combined deep brain stimulation (DBS) with capsulotomy for comorbid motor and psychiatric symptoms in patients with Tourette's syndrome (TS). METHODS: This retrospective cohort study consecutively enrolled TS patients with comorbid motor and psychiatric symptoms who were treated with combined DBS and anterior capsulotomy at our center. Longitudinal motor, psychiatric, and cognitive outcomes and quality of life were assessed. In addition, a systematic review and meta-analysis were performed to summarize the current experience with the available evidence. RESULTS: In total, 5 eligible patients in our cohort and 26 summarized patients in 6 cohorts were included. After a mean 18-month follow-up, our cohort reported that motor symptoms significantly improved by 62.4 % (P = 0.005); psychiatric symptoms of obsessive-compulsive disorder (OCD) and anxiety significantly improved by 87.7 % (P < 0.001) and 78.4 % (P = 0.009); quality of life significantly improved by 61.9 % (P = 0.011); and no significant difference was found in cognitive function (all P > 0.05). Combined surgery resulted in greater improvements in psychiatric outcomes and quality of life than DBS alone. The synthesized findings suggested significant improvements in tics (MD: 57.92, 95 % CI: 41.28-74.56, P < 0.001), OCD (MD: 21.91, 95 % CI: 18.67-25.15, P < 0.001), depression (MD: 18.32, 95 % CI: 13.26-23.38, P < 0.001), anxiety (MD: 13.83, 95 % CI: 11.90-15.76, P < 0.001), and quality of life (MD: 48.22, 95 % CI: 43.68-52.77, P < 0.001). Individual analysis revealed that the pooled treatment effects on motor symptoms, psychiatric symptoms, and quality of life were 78.6 %, 84.5-87.9 %, and 83.0 %, respectively. The overall pooled rate of adverse events was 50.0 %, and all of these adverse events were resolved or alleviated with favorable outcomes. CONCLUSIONS: Combined DBS with capsulotomy is effective for relieving motor and psychiatric symptoms in TS patients, and its safety is acceptable. However, the optimal candidate should be considered, and additional experience is still necessary.

Skin-related complications following deep brain stimulation surgery: A single-center retrospective analysis of 525 patients who underwent DBS surgery.

BACKGROUND: Although Deep Brain Stimulation (DBS) is a safe and proven treatment modality for patients suffering from debilitating movement and neuropsychiatric disorders, it is not free from complications. Management of skin erosion and infection following DBS surgery constitutes a challenge in everyday clinical practice. OBJECTIVES: Skin-related complications were evaluated in patients who underwent DBS surgery due to Parkinson's disease (PD), dystonia, essential tremor (ET), and other indications including Tourette syndrome (TS), Obsessive-Compulsive Disorder (OCD), and epilepsy. METHODS: A retrospective analysis of clinical data was performed on patients who underwent DBS surgery between November 2008 and September 2021 at the Department of Neurosurgery, Institute of Psychiatry and Neurology, Warsaw. RESULTS: 525 patients who underwent 927 DBS leads implantations were included in the analysis. There were 398 patients with PD, 80 with dystonia, 26 with ET, 7 with drug-resistant epilepsy, 5 with Multiple Sclerosis, 4 with Holme's or cerebellar tremor, 3 with TS, and 2 with OCD. 42 patients (8,0%) had 78 skin infection episodes. The overall level of skin erosion was 3,8% (20/525 patients). The risk of developing infection episode was connected with younger age at diagnosis (p = 0.017) and at surgery (p = 0.023), whereas the development of skin erosion was connected with the dystonia diagnosis (p = 0.012). Patients with dystonia showed the highest rate of infections and erosions (11/70 and 7/70 patients retrospectively). DISCUSSION: Postoperative skin complications are a serious side effect of DBS surgery. CONCLUSION: Our study suggests that dystonic patients are at higher risk of developing skin-related complications after DBS surgery.

Improvement of Tourette syndrome symptoms after intractable temporal lobe epileptic surgery: a case report.

BACKGROUND: The comorbidities of either epilepsy or Tourette syndrome (TS) are heterogeneous. However, the co-occurrence of epilepsy and TS conditions is rarely encountered, let alone effective treatments that address both neurologic disorders at the same time. METHODS: We report a 24-year-old female patient who was diagnosed with TLE and TS. She presented for seizure control. After evaluation with stereo-electroencephalography and electrocorticography monitoring, the patient underwent a resective surgery treatment and was followed for 9 months. RESULTS: At the last follow-up, the patient remained seizure free and unexpectedly showed great improvement in TS symptoms and its psychiatric comorbidities. CONCLUSION: This anecdotal case highlights the close association between TLE and TS and we suggest that epilepsy and TS share some common pathophysiologic mechanisms.

Neurosurgical management of Tourette syndrome: A literature review and analysis of a case series treated with deep brain stimulation.

Tourette syndrome (TS) is a heterogeneous disorder, which clinical presentation includes both multiple motor and vocal tics and commonly associated psychiatric conditions (obsessive-compulsive disorder, attention deficit hyperactivity disorder, depression, anxiety, etc.). Treatment options primarily consist of non-pharmacological interventions (habit reversal training, relaxation techniques, cognitive behavioral therapy, and social rehabilitation) and pharmacotherapy. In case of the intractable forms, neurosurgical treatment may be considered, primarily deep brain stimulation (DBS). DBS appear to be effective in medically intractable TS patients, although, the preferential brain target is still not defined. The majority of studies describe small number of cases and the issues of appropriate patient selection and ethics remain to be clarified. In this article, we review the main points in management of TS, discuss possible indications and contraindications for neurosurgical treatment, and analyze our experience of DBS in a case series of refractory TS patients with the focus on target selection and individual outcomes.

Neuroanatomical considerations for optimizing thalamic deep brain stimulation in Tourette syndrome.

OBJECTIVE: Deep brain stimulation (DBS) of the centromedian thalamic nucleus has been reportedly used to treat severe Tourette syndrome, yielding promising outcomes. However, it remains unclear how DBS electrode position and stimulation parameters modulate the specific area and related networks. The authors aimed to evaluate the relationships between the anatomical location of stimulation fields and clinical responses, including therapeutic and side effects. METHODS: The authors collected data from 8 patients with Tourette syndrome who were treated with DBS. The authors selected the active contact following threshold tests of acute side effects and gradually increased the stimulation intensity within the therapeutic window such that acute and chronic side effects could be avoided at each programming session. The patients were carefully interviewed, and stimulation-induced side effects were recorded. Clinical outcomes were evaluated using the Yale Global Tic Severity Scale, the Yale-Brown Obsessive-Compulsive Scale, and the Hamilton Depression Rating Scale. The DBS lead location was evaluated in the normalized brain space by using a 3D atlas. The volume of tissue activated was determined, and the associated normative connective analyses were performed to link the stimulation field with the therapeutic and side effects. RESULTS: The mean follow-up period was 10.9 ± 3.9 months. All clinical scales showed significant improvement. Whereas the volume of tissue activated associated with therapeutic effects covers the centromedian and ventrolateral nuclei and showed an association with motor networks, those associated with paresthesia and dizziness were associated with stimulation of the ventralis caudalis and red nucleus, respectively. Depressed mood was associated with the spread of stimulation current to the mediodorsal nucleus and showed an association with limbic networks. CONCLUSIONS: This study addresses the importance of accurate implantation of DBS electrodes for obtaining standardized clinical outcomes and suggests that meticulous programming with careful monitoring of clinical symptoms may improve outcomes.

The 5 Pillars in Tourette Syndrome Deep Brain Stimulation Patient Selection: Present and Future.

The selection of patients with Tourette syndrome (TS) for deep brain stimulation (DBS) surgery rests on 5 fundamental pillars. However, the operationalization of the multidisciplinary screening process to evaluate these pillars remains highly diverse, especially across sites. High tic severity and tic-related impact on quality of life (first 2 pillars) require confirmation from objective, validated measures, but malignant features of TS should per se suffice to fulfill this pillar. Failure of behavioral and pharmacologic therapies (third pillar) should be assessed taking into account refractoriness through objective and subjective measures supporting lack of efficacy of all interventions of proven efficacy, as well as true lack of tolerability, adherence, or access. Educational interventions and use of remote delivery formats (for behavioral therapies) play a role in preventing misjudgment of treatment failure. Stability of comorbid psychiatric disorders for 6 months (fourth pillar) is needed to confirm the predominant impact of tics on quality of life, to prevent pseudo-refractoriness, and to maximize the future DBS response. The 18-year age limit (fifth pillar) is currently under reappraisal, considering the potential impact of severe tics in adolescence and the predictive effect of tic severity in childhood on tic severity when transitioning into adulthood. Future advances should aim at a consensus-based definition of failure of specific, noninvasive treatment strategies for tics and of the minimum clinical observation period before considering DBS treatment, the stability of behavioral comorbidities, and the use of a prospective international registry data to identify predictors of positive response to DBS, especially in younger patients.

Deep Brain Stimulation for Refractory Tourette Syndrome: Electrode Position and Clinical Outcome.

The efficacy of deep brain stimulation (DBS) for refractory Tourette syndrome (TS) is accepted, but whether the efficacy of DBS treatment in the Japanese population is equivalent to those reported internationally and whether adverse effects are comparable are not yet known. This study evaluated the clinical practice and outcome of DBS for TS in a Japanese institution. This study included 25 consecutive patients with refractory TS treated with thalamic centromedian-parafascicular nucleus DBS. The severity of tics was evaluated with the Yale Global Tic Severity Scale (YGTSS) before surgery, at 1 year after surgery, and at the last follow-up of 3 years or more after surgery. The occurrence of adverse events, active contact locations, and stimulation conditions were also evaluated. YGTSS tic severity score decreased by average 45.2% at 1 year, and by 56.6% at the last follow-up. The reduction was significant for all aspects of the scores including motor tics, phonic tics, and impairment. The mean coordinates of active contacts were 7.62 mm lateral to the midline, 3.28 mm posterior to the midcommissural point, and 3.41 mm above anterior commissure-posterior commissure plane. Efficacy and stimulation conditions were equivalent to international reports. The stimulation-induced side effects included dysarthria (32.0%) and paresthesia (12.0%). Device infection occurred in three patients (12.0%) as a surgical complication. The DBS device was removed because of infection in two patients. DBS is an effective treatment for refractory TS, although careful indication is necessary because of the surgical risks and unknown long-term outcome.

Sustained Relief after Pallidal Stimulation Interruption in Tourette's Syndrome Treated with Simultaneous Capsulotomy.

INTRODUCTION: Globus pallidus internus (GPi) deep brain stimulation (DBS) combined with anterior capsulotomy offers a promising treatment option for severe medication-refractory cases of Tourette's syndrome (TS) with psychiatric comorbidities. Several patients treated with this combined surgery experienced sustained relief after discontinuation of stimulation over the course of treatment. METHODS: Retrospectively, the medical records and clinical outcomes were reviewed of 8 patients (6 men; 2 women with mean age of 20.3 years) who had undergone bilateral GPi-DBS combined with anterior capsulotomy for medically intractable TS and psychiatric comorbidities. All patients had experienced an accidental interruption or intentional withdrawal of pallidal stimulation during treatment. RESULTS: The widespread clinical benefits achieved during the combined treatment were fully maintained after intentional or accidental DBS discontinuation. The improvement in overall tic symptoms achieved was on average 78% at the follow-up or close to the DBS discontinuation, while it was 83% at last follow-up (LFU). At LFU, most patients had functionally recovered; exhibited only mild tics; displayed minor or no obsessive-compulsive disorder symptoms, anxiety, or depression; and experienced a much better quality of life. CONCLUSION: Bilateral GPi-DBS combined with anterior capsulotomy appears to result in marked and sustained improvements in TS symptoms and psychiatric comorbidities, which are fully maintained over time, even without pallidal stimulation.

Differentiating tic electrophysiology from voluntary movement in the human thalamocortical circuit.

OBJECTIVES: Tourette syndrome is a neurodevelopmental disorder commonly associated with involuntary movements, or tics. We currently lack an ideal animal model for Tourette syndrome. In humans, clinical manifestation of tics cannot be captured via functional imaging due to motion artefacts and limited temporal resolution, and electrophysiological studies have been limited to the intraoperative environment. The goal of this study was to identify electrophysiological signals in the centromedian (CM) thalamic nucleus and primary motor (M1) cortex that differentiate tics from voluntary movements. METHODS: The data were collected as part of a larger National Institutes of Health-sponsored clinical trial. Four participants (two males, two females) underwent monthly clinical visits for collection of physiology for a total of 6 months. Participants were implanted with bilateral CM thalamic macroelectrodes and M1 subdural electrodes that were connected to two neurostimulators, both with sensing capabilities. MRI scans were performed preoperatively and CT scans postoperatively for localisation of electrodes. Electrophysiological recordings were collected at each visit from both the cortical and subcortical implants. RESULTS: Recordings collected from the CM thalamic nucleus revealed a low-frequency power (3-10 Hz) increase that was time-locked to the onset of involuntary tics but was not present during voluntary movements. Cortical recordings revealed beta power decrease in M1 that was present during tics and voluntary movements. CONCLUSION: We conclude that a human physiological signal was detected from the CM thalamus that differentiated tic from voluntary movement, and this physiological feature could potentially guide the development of neuromodulation therapies for Tourette syndrome that could use a closed-loop-based approach.

Treatment of tics associated with Tourette syndrome.

Motor and phonic tics associated with Tourette syndrome (TS) can range in severity from barely perceptible to disabling and most patients have a variety of behavioral co-morbidities, particularly, attention deficit disorder and obsessive compulsive disorder. Therefore, therapy must be tailored to the individual needs of the patients. In addition to behavioral therapy, oral medications such as alpha agonists, dopamine depletors, anti-psychotics, and topiramate are used to control the involuntary movements and noises. Botulinum toxin injections are particularly effective in patients with troublesome focal motor and phonic tics, including coprolalia. Deep brain stimulation may be considered for patients with "malignant" TS, that is, refractory to medical therapy. When appropriate therapy is selected and implemented, most patients with TS can achieve their full potential and lead essentially normal life.

Paediatric Moyamoya Disease and Tourette's Syndrome: An Unusual Association Responding Favourably to Direct and Indirect Cerebral Revascularisation Surgery.

BACKGROUND: Moyamoya disease, an uncommon chronic intra-cerebral arteriopathy asymmetrically affecting the proximal vasculature, is rarely associated with clinical features pertaining to movement disorders. CASE DESCRIPTION: A 5-year-and-9-month-old boy developed repetitive episodic involuntary winking of the right eye along with ipsilateral shoulder shrugging movements in an absolutely conscious state, associated with paroxysmal shouts and loud laughs and punctuated with abusive verbal expressions (coprolalia). These episodic features, over the course of the next 1.5 years, got progressively accentuated by situations which evoked stress. In addition, there was progressive regression of verbal and cognitive milestones, emotional lability and aspects of attention deficit hyperkinetic disorder. The child was evaluated by a neurologist with magnetic resonance imaging of the brain, which showed characteristic ischaemic areas involving the basal ganglia and fronto-parietal cortical areas along the middle cerebral artery territory, predominantly on the left side. Subsequent cerebral angiography revealed extensive stenosis of bilateral (predominantly left-sided) internal cerebral arteries and middle cerebral arteries with evidence of diffuse leptomeningeal collaterals. The electroencephalography was reported to be normal. He was eventually diagnosed to be suffering from Moyamoya disease with associated Tourette's syndrome. Subsequently, the child underwent left-sided superficial temporal artery to middle cerebral artery anastomosis along with encephalo-duro-arterio-myo-synangiosis. Significant clinico-radiological improvement was noted after 3 months. The clinical deficiencies had dramatically resolved. There was evidence of excellent development of both direct and indirect surgical collaterals along the left middle cerebral artery territory. He could go back to school. CONCLUSION: Ours is probably the first case reporting an association of paediatric Moyamoya disease with Tourette's syndrome, which significantly resolved after cerebral revascularisation surgery.

Progress in Pharmacological and Surgical Management of Tourette Syndrome and Other Chronic Tic Disorders.

BACKGROUND: Tourette syndrome (TS) and other chronic tic disorders are clinically heterogenous and cause physical discomfort, social difficulties, and emotional distress. In addition to tics, TS patients have a variety of behavioral comorbidities, including obsessive-compulsive disorders and attention-deficit hyperactivity disorders. TS treatment is multidisciplinary, involving behavioral therapy, oral medications, and botulinum toxin injections. METHODS: Relevant studies on pharmacological and surgical treatment options for TS and other chronic tic disorders, their limitations and current recommendations were reviewed using the PubMed search till April 2, 2018. Besides, the reference lists of the retrieved publications were manually searched to explore other relevant studies. This review aims to discuss the progress in pharmacological and surgical treatment options for TS and other chronic tic disorders. RESULTS AND CONCLUSIONS: Both typical and atypical antipsychotic agents are mainstays of pharmacological treatment of TS and other chronic tic disorder patients; however, their use is limited by serious side effects considering their potential of dopamine blockade. Because of the phenotypic variability, no medication has proven effective for all persons with TS and other chronic tic disorders. Botulinum toxin has emerged as a good therapeutic option, especially for focal and dystonic tics. But, their uses are limited by lack of sufficient evidence and high cost. Surgical treatment is considered in medically refractory and severely disabled tics patients. Deep brain stimulation has replaced lesional surgeries; however, there is uncertainty regarding the selection of patients and target of stimulation.

Globus Pallidus Internus Electric High-Frequency Stimulation Modulates Dopaminergic Activity in the Striatum of a Rat Model of Tourette Syndrome.

OBJECTIVE: The purpose of this study was to investigate the role of deep brain stimulation (DBS) of the globus pallidus internus (GPi) in dopamine and dopamine transporter metabolism and to explore the regulatory role of DBS on dopaminergic neurons in Tourette syndrome by constructing an autoimmune model. METHODS: Serum with high concentrations of antinuclear antibodies or phosphate-buffered saline solution was injected into the striatum of rats by a stereotactic technique and micropump. Then, electrodes were planted in the rats' globus pallidus internus. Concentrations of dopamine and dopamine transporter in the striatum were detected by enzyme-linked immunosorbent assay, immunohistochemistry, and Western blot analysis after 7 days of high-frequency stimulation (130 Hz). RESULTS: The tic behavior score of rats in the Tourette syndrome group was higher than that of rats in the control group (P < 0.01). After high-frequency stimulation, the scores of the Tourette syndrome model group and the control group significantly decreased. The concentration of dopamine in the Tourette syndrome model group and the control group also significantly decreased after electric stimulation (P < 0.05). In addition, immunohistochemical analysis and Western blot test results showed that dopamine transporter in the Tourette syndrome model nonstimulation group was lower than in the Tourette syndrome model stimulation group, and that dopamine transporter in the control nonstimulation group was lower than in the control stimulation group (P < 0.05). CONCLUSIONS: The results of this study show that the mechanism of DBS of the GPi in the treatment of Tourette syndrome involved monoamine neurotransmitters, especially the dopamine system, that affected the metabolism and transport of corresponding neurotransmitters, playing an important role in regulating the concentration of synaptic neurotransmitters and changing the biologic activity of basal ganglia nerve circuits.

DBS in pediatric patients: institutional experience.

INTRODUCTION: DBS is initially used for treatment of essential tremor and Parkinson's disease in adults. In 1996, a child with severe life-threatening dystonia was offered DBS to the internal globus pallidus (GPi) with lasting efficacy at 20 years. Since that time, increasing number of children benefited from DBS. PATIENTS AND METHODS: We retrospectively evaluated our database of patients who underwent DBS from 2011 to 2017. All patients ≤ 17 years of age at the time of implantation of DBS were included in this series. Subjective Benefit Rating Scale (SBRS), Hoehn Yahr Scale (HYS), Fahn Marsden Rating Scale (FMRS), Clinical Global Impressions Scales (CGI), and Yale Global Tic Severity Scale (YGT) were used to evaluate clinical outcome. RESULTS: Between May 2014 and October 2017, 11 children underwent DBS procedure in our institution. Six of them were female and five of them were male. Mean age at surgery was 11.8 ± 4.06 years (range 5-17 years). In our series, four patients had primary dystonia (PDY) (36.3%), three patients had secondary dystonia (SDY) (27.2%), two patients had JP (18.1%), and two patients had Tourette Syndrome (TS) (18.1%). Two JP patients underwent bilateral STN DBS while the other nine patients underwent bilateral GPi DBS. SBRS scores were 1.75 ± 0.5 for patients with PDY, 3 ± 0 for patients with JP, 2.5 ± 0.7 for patients with TS, and 2 ± 1 for patients with SDY. Mean FMRS reduction rate was 40.5 for patients with dystonia. Significant improvement was also defined in patients with TS and JP after DBS. None of the patients experienced any intracerebral hemorrhage or other serious adverse neurological effect related to the DBS. Wound complications occurred in two patients. CONCLUSION: There are many literatures that support DBS as a treatment option for pediatric patients with medically refractory neurological disorders. DBS has replaced ablative procedures as a treatment of choice not only for adult patients, but also for pediatric patients. Wound-related complications still remain the most common problem in pediatric patients. Development of smaller and more flexible hardware will improve quality of children's life and minimize wound-related complications in the future.

Thalamic Deep Brain Stimulation.

The use of deep brain stimulation (DBS) of the thalamus has been proven to be a safe and efficacious treatment for the management of many diseases. The most common indication for thalamic DBS remains essential tremor (ET), one of the most common movement disorders in the world. ET patients should be considered for surgical intervention when their tremor has demonstrated to be refractory to medication, a characteristic estimated to be present in roughly 50% of ET cases. Advantages of DBS over thalamotomy include its reversibility, the ability to adjust stimulation settings to optimize efficacy and minimize side effects, the ability to perform bilateral procedures safely, and an association with a lower risk of postoperative cognitive problems. The most common target of DBS for ET is the ventralis intermedius (VIM) of the thalamus, and the optimal electrode location corresponds to the anterior margin of the VIM. Other indications for thalamic DBS include non-ET tremor, obsessive-compulsive disorder, neuropathic pain, traumatic brain injury, Tourette's syndrome, and drug-resistant epilepsy among others.

"I swear, I can't stop it!" - A case of severe Tourette's syndrome treated with deep brain stimulation of anteromedial globus pallidus interna.

INTRODUCTION: Tourette's syndrome (TS) is a complex neuropsychiatric disorder characterized by the presence of multiple motor and vocal tics. Here, we report the case of a young man with severe TS refractory to multiple medications who underwent deep brain stimulation (DBS), which was successful in substantially ameliorating his tics. To our knowledge, this is the first such report from India and South Asia. CASE REPORT: An 18-year-old right-handed male patient was diagnosed with TS at the age of 10 years. He had facial and ocular tics. He was also hitting his fist against his chest and shouting obscenities. The manifestations would be present in every waking hour with a maximum tic free interval of 15-20 minutes. They would often result in self-injury or damage to objects. He would have frequent crying spells, anger outbursts, and death wishes. As tics became highly conspicuous and socially inappropriate, he dropped out of school and remained almost completely house-bound for the preceding year. On evaluation, he scored 96 (46 on tic-severity subscale and 50 on impairment subscale) of a maximum of 100 on the Yale Global Tic Severity Scale. (YGTSS). MANAGEMENT: After failure of multiple combinations of medicines, repetitive transcranial magnetic stimulation, and behavioural therapies, he successfully underwent DBS to bilateral anteromedial globus pallidus interna. CONCLUSION: Tic severity reduced substantially post-surgery, with the YGTSS score improving by more than 72%. These improvements were sustained on follow-up visits with the patient successfully returning to join college. To our knowledge, this is the first such report from India and South Asia.

Comparative characterization of single cell activity in the globus pallidus internus of patients with dystonia or Tourette syndrome.

Altered processing in the basal ganglia has been described both in dystonia and Tourette's syndrome (TS). Deep brain stimulation (DBS) of the globus pallidus internus (GPi) has become a recognized treatment for dystonia and has been used successfully to alleviate tics in TS. This study evaluates possible differences of GPi linear and nonlinear neuronal discharge characteristics between patients with dystonia and TS. Nine patients with primary dystonia and six patients with TS were studied during functional stereotactic neurosurgical operations for implantation of DBS electrodes under general anesthesia. Six patients with primary dystonia under local anesthesia served as non-anesthetized controls. Single-unit activity recordings in the GPi were obtained during routine microelectrode recording and mapping to delineate nuclear borders and to identify the sensorimotor subregions. Anesthesia profoundly decreased neuronal activity in patients with dystonia. Dystonia patients showed marginally higher mean firing rates in the GPi compared to TS patients (P = 0.06). Although the average total number of bursts and the mean peak frequency in bursts did not differ between groups, the mean spikes in bursts were higher in dystonia patients (P < 0.05). Nonlinear time series analysis metrics, measured as complexity of Lempel-Ziv and maximum approximate entropy, revealed higher randomness in TS compared to dystonia patients (P < 0.05). The percentage of oscillating neurons in spike trains was higher in dystonia compared to TS (P < 0.05). Our data provide evidence for differences of the neuronal dynamic complexity, randomness and oscillatory modulation of spike trains in the GPi between dystonia and TS. Such differences, although subtle, might contribute to the specific clinical phenomenology secondary to disordered neuronal basal ganglia processing.