Identification and management of deep brain stimulation intra- and postoperative urgencies and emergencies

Deep brain stimulation in Parkinson's disease: A scientometric and bibliometric analysis, trends, and research hotspots

Parkinson disease (PD), a prevalent neurodegenerative ailment in the elderly, relies mainly on pharmacotherapy, yet deep brain stimulation (DBS) emerges as a vital remedy for refractory cases. This study performs a bibliometric analysis on DBS in PD, delving into research trends and study impact to offer comprehensive insights for researchers, clinicians, and policymakers, illuminating the current state and evolutionary trajectory of research in this domain. A systematic search on March 13, 2023, in the Scopus database utilized keywords like "Parkinson disease," "PD," "Parkinsonism," "Deep brain stimulation," and "DBS." The top 1000 highly cited publications on DBS in PD underwent scientometric analysis via VOS Viewer and R Studio's Bibliometrix package, covering publication characteristics, co-authorship, keyword co-occurrence, thematic clustering, and trend topics. The bibliometric analysis spanned 1984 to 2021, involving 1000 cited articles from 202 sources. The average number of citations per document were 140.9, with 31,854 references. "Movement Disorders" led in publications (n = 98), followed by "Brain" (n = 78) and "Neurology" (n = 65). The University of Oxford featured prominently. Thematic keyword clustering identified 9 core research areas, such as neuropsychological function and motor circuit electrophysiology. The shift from historical neurosurgical procedures to contemporary focuses like "beta oscillations" and "neuroethics" was evident. The bibliometric analysis emphasizes UK and US dominance, outlining 9 key research areas pivotal for reshaping Parkinson treatment. A discernible shift from invasive neurosurgery to DBS is observed. The call for personalized DBS, integration with NIBS, and exploration of innovative avenues marks the trajectory for future research.

Electrocardiographic approach strategies in patients with Parkinson disease treated with deep brain stimulation

Deep brain stimulation (DBS) is an interdisciplinary and reversible therapy that uses high-frequency electrical stimulation to correct aberrant neural pathways in motor and cognitive neurological disorders. However, the high frequency of the waves used in DBS can interfere with electrical recording devices (e.g., electrocardiogram, electroencephalogram, cardiac monitor), creating artifacts that hinder their interpretation. The compatibility of DBS with these devices varies and depends on factors such as the underlying disease and the configuration of the neurostimulator. In emergencies where obtaining an electrocardiogram is crucial, the need for more consensus on reducing electrical artifacts in patients with DBS becomes a significant challenge. Various strategies have been proposed to attenuate the artifact generated by DBS, such as changing the DBS configuration from monopolar to bipolar, temporarily deactivating DBS during electrocardiographic recording, applying frequency filters both lower and higher than those used by DBS, and using non-standard leads. However, the inexperience of medical personnel, variability in DBS models, or the lack of a controller at the time of approach limit the application of these strategies. Current evidence on their reproducibility and efficacy is limited. Due to the growing elderly population and the rising utilization of DBS, it is imperative to create electrocardiographic methods that are easily accessible and reproducible for general physicians and emergency services.

Precision Mapping of Thalamic Deep Brain Stimulation Lead Positions Associated With the Microlesion Effect in Tourette Syndrome

BACKGROUND

The microlesion effect refers to the improvement of clinical symptoms after deep brain stimulation (DBS) lead placement and is suggested to indicate optimal lead placement. Very few studies have reported its implications in neuropsychiatric disorders.

OBJECTIVE

To evaluate the magnitude of the microlesion effect in Tourette syndrome and the relationship between the microlesion effect and the anatomic location of implanted DBS leads.

METHODS

Six male patients were included. Their median age at surgery and follow-up period were 25 years (range, 18-47) and 12 months (range, 6-24), respectively. All patients were videotaped pre- and postoperatively, and tic frequencies were counted. We also analyzed the precision of lead placement and evaluated the normative connectome associated with the microlesion area.

RESULTS

The microlesion effect was observed as an improvement in tic symptoms in all patients, and the long-term clinical outcomes were favorable. The median motor tic frequency was 20.2 tics/min (range, 9.7-60) at baseline and decreased to 3.2 tics/min (1.2-11.3) in patients on postoperative day 1 ( P = .043) and to 5.7 tics/min (range, 1.9-16.6) in patients on postoperative day 7 ( P = .028). Phonic tic tended to improve immediately after surgery although the changes were not significant. Image analyses revealed that the precise position of the electrode was directed toward the anteromedial centromedian nucleus. Normative connectome analysis demonstrated connections between improvement-related areas and wide areas of the prefrontal cortex.

CONCLUSION

This study shows that the microlesion effect may seem as an immediate improvement after optimal DBS lead placement in patients with Tourette syndrome.

Evaluation of Deep Brain Stimulation (DBS) Lead Biomechanical Interaction with Brain Tissue

The current study aims to examine the effect of material properties on implanted leads used for deep brain stimulation (DBS) using finite element (FE) analysis to investigate brain deformation around an implanted DBS lead in response to daily head accelerations. FE analysis was used to characterize the relative motion of the DBS lead in a suite of fifteen cases sampled from a previously derived kinematic envelope representative of everyday activities describing translational and rotational pulse shape, magnitude, and duration. Load curves were applied to the atlas-based brain model (ABM) with a scaled Haversine acceleration pulse in four directions of rotation: + X, - Y, + Y, and + Z. In addition to the fifteen sampled cases, six experimental cases taken from a previous literature review were also simulated for comparison. The current investigation found that there was very little difference in brain response for the DBS leads with two different material properties. In general, the brain and DBS lead experienced the greatest deformation during rotation about the Z axis for similar load cases. In conclusion, this study showed that there was no significant difference in implanted DBS lead deformation based on lead material properties.

Connectivity correlates to predict essential tremor deep brain stimulation outcome: Evidence for a common treatment pathway

BACKGROUND AND PURPOSE

Deep brain stimulation (DBS) is the most common surgical treatment for essential tremor (ET), yet there is variation in outcome and stimulation targets. This study seeks to consolidate proposed stimulation "sweet spots," as well as assess the value of structural connectivity in predicting treatment outcomes.

MATERIALS AND METHODS

Ninety-seven ET individuals with unilateral thalamic DBS were retrospectively included. Using normative brain connectomes, structural connectivity measures were correlated with the percentage improvement in contralateral tremor, based on the Fahn-Tolosa-Marin tremor rating scale (TRS), after parameter optimization (range 3.1-12.9 months) using a leave-one-out cross-validation in 83 individuals. The predictive feature map was used for cross-validation in a separate cohort of 14 ET individuals treated at another center. Lastly, estimated volumes of tissue activated (VTA) were used to assess a treatment "sweet spot," which was compared to seven previously reported stimulation sweet spots and their relationship to the tract identified by the predictive feature map.

RESULTS

In the training cohort, structural connectivity between the VTA and dentato-rubro-thalamic tract (DRTT) correlated with contralateral tremor improvement (R = 0.41; p < 0.0001). The same connectivity profile predicted outcomes in a separate validation cohort (R = 0.59; p = 0.028). The predictive feature map represented the anatomical course of the DRTT, and all seven analyzed sweet spots overlapped the predictive tract (DRTT).

CONCLUSIONS

Our results strongly support the possibility that structural connectivity is a predictor of contralateral tremor improvement in ET DBS. The results suggest the future potential for a patient-specific functionally based surgical target. Finally, the results showed convergence in "sweet spots" suggesting the importance of the DRTT to the outcome.

Implantable Pulse Generators for Deep Brain Stimulation: Challenges, Complications, and Strategies for Practicality and Longevity

Deep brain stimulation (DBS) represents an important treatment modality for movement disorders and other circuitopathies. Despite their miniaturization and increasing sophistication, DBS systems share a common set of components of which the implantable pulse generator (IPG) is the core power supply and programmable element. Here we provide an overview of key hardware and software specifications of commercially available IPG systems such as rechargeability, MRI compatibility, electrode configuration, pulse delivery, IPG case architecture, and local field potential sensing. We present evidence-based approaches to mitigate hardware complications, of which infection represents the most important factor. Strategies correlating positively with decreased complications include antibiotic impregnation and co-administration and other surgical considerations during IPG implantation such as the use of tack-up sutures and smaller profile devices.Strategies aimed at maximizing battery longevity include patient-related elements such as reliability of IPG recharging or consistency of nightly device shutoff, and device-specific such as parameter delivery, choice of lead configuration, implantation location, and careful selection of electrode materials to minimize impedance mismatch. Finally, experimental DBS systems such as ultrasound, magnetoelectric nanoparticles, and near-infrared that use extracorporeal powered neuromodulation strategies are described as potential future directions for minimally invasive treatment.

A systematic review of Twiddler's syndrome: a hardware-related complication of deep brain stimulation

Twiddler's syndrome (TS) is a hardware-related complication of deep brain stimulation which has not been well documented and is probably underreported. The objective of this study is to comprehensively describe TS by systematically reviewing the related literature. The methods include selecting the eligible studies based on the inclusion and exclusion criteria. Data about studies and TS were collected. A descriptive statistical analysis of the extracted data was performed. We found 18 eligible studies describing 23 patients with TS. The mean age of the 23 patients was 61.4 ± 15.9 years (range, 16-79 years.). The percentage of TS in the female population was 91.3% (females: 21/23). The incidence of postoperative TS was 1.4% (6 out of 437) per patient and 1.1% (8 out of 709) per extension wire. The mean time to clinical presentation was 9.9 ± 10.3 months (range, 0.5-36 months). Nineteen of the twenty-three patients presented with a rebound of previous symptoms. Twelve of the twenty-three patients had high impedance at the postoperative checkup of the DBS system. A plain X-ray indicated twisted extension wires in almost all these patients. All patients meeting the definition of postoperative device-related TS underwent revision surgery. TS is more prevalent in females. Based on the typical clinical symptoms (rebound of the previous symptoms, high impedance, and X-ray demonstration), the differential diagnosis can often be straightforward. TS should thus be taken into consideration when attempting to explain or rule out hardware malfunction. The timely recognition and proper revision of TS can prevent further serious damage.

Evolution of Globus Pallidus Targeting for Parkinson's and Dystonia Deep Brain Stimulation: A 15-Year Experience

Objective: The aim of this study is to evaluate the evolution of GPi DBS targeting.

Methods: This retrospective, single-center study included patients implanted with GPi DBS leads for dystonia or PD during the years 2004 to 2018 at the University of Florida Fixel Institute for Neurological Diseases. Each patient underwent a high-resolution targeting study on the day prior to the surgery, which was fused with a high resolution CT scan that was acquired on the day of the procedure. Intraoperative target location was selected using a digitized 3D Schaltenbrand-Bailey atlas. All patients underwent a high-resolution head CT scan without contrast approximately one month after lead implantation and accurate measurement of neuroanatomical lead position was acquired after fusion of pre-operative and post-operative image studies.

Results: We analyzed 253 PD patients with 352 leads and 80 dystonia patients with 141 leads. During 15 years of follow-up, lead locations in the PD group migrated more laterally (β = 0.09, p < 0.0001), posteriorly [slope (β) = 0.04, p < 0.05], and dorsally (β = 0.07, p < 0.001), whereas leads in the dystonia group did not significantly change position aside from a trend in the dorsal direction (β = 0.06, p = 0.053).

Conclusion: The evolving target likely results from multiple factors including improvements in targeting techniques and clinical feedback intraoperatively and post-operatively. Our demonstrates the potential importance of a systematic post-operative DBS lead measurement protocol to ensure quality control and to inform and optimize DBS programming.

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.

A mechanical analysis informed fractography study on load-specific fatigue behaviors of Pt-Ir coils used in implantable medical leads

Fatigue fracture is a major threaten to implantable medical coils such as platinum-iridium (Pt-Ir) coils used in deep brain stimulation leads. The fractography under bending and torsion fatigue was studied in comparison with mechanical analysis to grasp load-specific fatigue characteristics and understand the mechanisms. Mechanical analysis of the coil under bending and torsion was conducted with both analytical and numerical methods. Pt-Ir coils were experimentally fatigued at roughly paralleled bending and torsional load levels. The fatigue life was recorded and the fracture morphology was observed and analyzed. It is revealed that the helical structure of the coil turns bending and torsion loads into different locally distributed stresses, which mainly determine the fatigue behaviors. Features of fracture morphology, such as ratchet mark and fatigue striation, are identifiable to differentiate load types and stress levels. Both bending and torsion may play important roles in fatigue fractures of the coil. The study proposes an effective approach to study load-specific fatigue characteristics of medical coils which provides fundamental knowledge for medical lead design and clinical fracture diagnosis.

Surgical management of adverse events associated with deep brain stimulation: A single-center experience

Objectives:

Deep brain stimulation is widely used to treat movement disorders and selected neuropsychiatric disorders. Despite the fact, the surgical methods vary among centers. In this study, we aimed to evaluate our own surgical complications and how we performed surgical troubleshooting.

Methods:

A retrospective chart review was performed to evaluate the clinical data of patients who underwent deep brain stimulation surgery and deep brain stimulation–related procedures at our center between October 2014 and September 2019. We reviewed surgical complications and how surgical troubleshooting was performed, regardless of where the patient underwent the initial surgery.

Results:

A total of 92 deep brain stimulation lead implantation and 43 implantable pulse generator replacement procedures were performed. Among the 92 lead implantation procedures, there were two intracranial lead replacement surgeries and one deep brain stimulation lead implantation into the globus pallidus to add to existing deep brain stimulation leads in the bilateral subthalamic nuclei. Wound revision for superficial infection of the implantable pulse generator site was performed in four patients. There was neither intracerebral hemorrhage nor severe hardware infection in our series of procedures. An adaptor (extension cable) replacement was performed due to lead fracture resulting from a head trauma in two cases.

Conclusion:

We report our experience of surgical management of adverse events associated with deep brain stimulation therapy with clinical vignettes. Deep brain stimulation surgery is a safe and effective procedure when performed by a trained neurosurgeon. It is important for clinicians to be aware that there are troubles that are potentially manageable with optimal surgical treatment.

Emergencies and critical issues in Parkinson's disease

Complications from Parkinson’s disease may develop over the disease course, sometimes unexpectedly, and require prompt or even urgent medical intervention. The most common are associated with aggravation of motor symptoms; serious non-motor complications, such as psychosis, orthostatic hypotension or sleep attacks, also occur. Here we review such complications, their clinical presentation, precipitating factors and management, including those related to using device-aided therapies. Early recognition and prompt attention to these critical situations is challenging, even for the Parkinson’s disease specialist, but is essential to prevent serious problems.

Early detection of cerebral ischemic events on intraoperative magnetic resonance imaging during surgical procedures for deep brain stimulation

BACKGROUND

Although intracerebral hemorrhage is the most feared complication of deep brain stimulation (DBS) surgery, cerebral ischemic events in association with DBS surgery have only rarely been described. We therefore evaluated the role of intraoperative MRI (iMRI) for early identification of cerebral ischemic events during DBS procedures and determined how ischemic infarctions affect patients over acute and long-term periods.

METHODS

Between January 2010 and December 2017, 1160 DBS electrodes were implanted in 595 patients at Chinese People's Liberation Army General Hospital, with the help of iMRI. The iMRI was performed in all patients after implantation, to define the accuracy of lead placement and detect complications. A CT scan was performed on postoperative days 1 to 7.

RESULTS

The iMRI showed that cerebral ischemic changes happened in nine (1.51% of patients, 0.78% of leads) patients. Only two (0.34%) of nine patients had an ischemic infarction in the basal ganglia, while seven (1.18%) had cortical ischemia. Six (67%) of the nine patients had long-term complications, two with mild hemiparesis, two with seizures, one with language dysfunction, and one with memory loss. Of those with a cortical ischemic infarction, only three (42.86%) of seven patients had no long-term complications. Long-term follow-up imaging showed that not all the patients recovered normal morphological structure in the area of ischemic foci. The factors of sex, age, target, and anesthesia were not related to ischemic events. In six (66.7%) cases, the entry point on the cortex or the path was not ideal.

CONCLUSIONS

Intraoperative ischemic events are not uncommon in DBS surgery. Ischemia can cause serious permanent complications, and regions subject to severe ischemia cannot be restored; it is therefore necessary to pay careful attention to any signs of ischemia. iMRI objectively provides the basis for early diagnosis of intraoperative ischemic infarction, providing guidance for follow-up treatment. The deviation in the entry point on the cortex or in the path resulted in vascular injury; it may be the key cause of ischemic events during DBS procedures.

Life-threatening DBS withdrawal syndrome in Parkinson's disease can be treated with early reimplantation

INTRODUCTION

The deep brain stimulation (DBS) withdrawal syndrome (DBS-WDS) is a rare, life-threatening complication in Parkinson's disease (PD) patients with long disease duration and stimulation when stimulation is terminated for extended periods mostly due to infection of the DBS-hardware.

METHODS, RESULTS

In five patients explantation became necessary because of infection after a mean of 11.4 years (range 4-15 years) of DBS and a mean disease duration of 24.6 years (range 3-22 years). Mean UPDRS motor-score pre-explantation was 38 points (range 24-55 points) which increased to a mean of 78.4 points (range 58-90 points) after explantation, despite optimal Levodopa dosing. Reimplantation of the hardware after 23 days (range 3-45 days) under antibiotic treatment led to an improvement to a mean of 40 points (range 25-73 points) and a complication free survival.

CONCLUSION

Early reimplantation of the DBS-hardware is a treatment option of the DBS-WDS when the life-threatening urgency overrides surgical standards. Observation of the syndrome indicates pharmacological unresponsiveness of the dopaminergic system in advanced PD and long-term DBS.

Deep brain stimulation for stroke: Current uses and future directions

BACKGROUND

Survivors of stroke often experience significant disability and impaired quality of life related to ongoing maladaptive responses and persistent neurologic deficits. Novel therapeutic options are urgently needed to augment current approaches. One way to promote recovery and ameliorate symptoms may be to electrically stimulate the surviving brain. Various forms of brain stimulation have been investigated for use in stroke, including deep brain stimulation (DBS).

OBJECTIVE/METHODS

We conducted a comprehensive literature review in order to 1) review the use of DBS to treat post-stroke maladaptive responses including pain, dystonia, dyskinesias, and tremor and 2) assess the use and potential utility of DBS for enhancing plasticity and recovery from post-stroke neurologic deficits.

RESULTS/CONCLUSIONS

A large variety of brain structures have been targeted in post-stroke patients, including motor thalamus, sensory thalamus, basal ganglia nuclei, internal capsule, and periventricular/periaqueductal grey. Overall, the reviewed clinical literature suggests a role for DBS in the management of several post-stroke maladaptive responses. More limited evidence was identified regarding DBS for post-stroke motor deficits, although existing work tentatively suggests DBS-particularly DBS targeting the posterior limb of the internal capsule-may improve paresis in certain circumstances. Substantial future work is required both to establish optimal targets and parameters for treatment of maladapative responses and to further investigate the effectiveness of DBS for post-stroke paresis.

Postoperative lead migration in deep brain stimulation surgery: Incidence, risk factors, and clinical impact

Introduction

Deep brain stimulation (DBS) is an effective treatment for multiple movement disorders and shows substantial promise for the treatment of some neuropsychiatric and other disorders of brain neurocircuitry. Optimal neuroanatomical lead position is a critical determinant of clinical outcomes in DBS surgery. Lead migration, defined as an unintended post-operative displacement of the DBS lead, has been previously reported. Despite several reports, however, there have been no systematic investigations of this issue. This study aimed to: 1) quantify the incidence of lead migration in a large series of DBS patients, 2) identify potential risk factors contributing to DBS lead migration, and 3) investigate the practical importance of this complication by correlating its occurrence with clinical outcomes.

Methods

A database of all DBS procedures performed at UF was queried for patients who had undergone multiple post-operative DBS lead localization imaging studies separated by at least two months. Bilateral DBS implantation has commonly been performed as a staged procedure at UF, with an interval of six or more months between sides. To localize the position of each DBS lead, a head CT is acquired ~4 weeks after lead implantation and fused to the pre-operative targeting MRI. The fused targeting images (MR + stereotactic CT) acquired in preparation for the delayed second side lead implantation provide an opportunity to repeat the localization of the first implanted lead. This paradigm offers an ideal patient population for the study of delayed DBS lead migration because it provides a large cohort of patients with localization of the same implanted DBS lead at two time points. The position of the tip of each implanted DBS lead was measured on both the initial post-operative lead localization CT and the delayed CT. Lead tip displacement, intracranial lead length, and ventricular indices were collected and analyzed. Clinical outcomes were characterized with validated rating scales for all cases, and a comparison was made between outcomes of cases with lead migration versus those where migration of the lead did not occur.

Results

Data from 138 leads in 132 patients with initial and delayed lead localization CT scans were analyzed. The mean distance between initial and delayed DBS lead tip position was 2.2 mm and the mean change in intracranial lead length was 0.45 mm. Significant delayed migration (>3 mm) was observed in 17 leads in 16 patients (12.3% of leads, 12.1% of patients). Factors associated with lead migration were: technical error, repetitive dystonic head movement, and twiddler’s syndrome. Outcomes were worse in dystonia patients with lead migration (p = 0.035). In the PD group, worse clinical outcomes trended in cases with lead migration.

Conclusions

Over 10% of DBS leads in this large single center cohort were displaced by greater than 3 mm on delayed measurement, adversely affecting outcomes. Multiple risk factors emerged, including technical error during implantation of the DBS pulse generator and failure of lead fixation at the burr hole site. We hypothesize that a change in surgical technique and a more effective lead fixation device might mitigate this problem.

Deep Brain Stimulation Emergencies: How the New Technologies Could Modify the Current Scenario

After 25 years of deep brain stimulation (DBS) for the treatment of Parkinson's disease, it has become increasingly recognized that a range of postoperative urgent situations and emergencies may occur. In this review we describe the possible scenarios of DBS-related emergencies: perioperative (intraoperative and early postoperative) and postoperative settings and issues from suboptimal control of motor and nonmotor symptoms in the early programming phase and during long-term follow-up. We also outline potential advantages in the management of these emergencies offered by the newest devices, emerging technologies, and new possibilities in programming.

Sedation During Surgery for Movement Disorders and Perioperative Neurologic Complications: An Observational Study Comparing Local Anesthesia, Remifentanil, and Dexmedetomidine

BACKGROUND

The anesthetic management of patients requiring surgery for movement disorders needs to balance microrecording quality and patient cooperation with safety and comfort. Anesthetics can alter microrecording, although the effect on outcome is debatable. They also provide a rested and cooperative patient and minimize complications such as intracranial hemorrhage by providing better hemodynamic control. Most teams use local anesthesia with monitored anesthesia care or conscious sedation with propofol. Recently, dexmedetomidine has emerged as an alternative that, at low doses, does not affect microrecording, and that does not impair respiratory drive.

METHODS

In the past 15 years, we have used in our institution local anesthesia, remifentanil, or dexmedetomidine sedation. We compared functional outcome and rate of complications in a group of 145 patients with similar characteristics.

RESULTS

We found 5 (3.4%) intracranial hemorrhages. Two (1.4%) were symptomatic. The remifentanil group had the highest risk of having systolic blood pressure >160 mm Hg during surgery (odds ratio [OR], 2.8; 95% confidence interval [CI], 0.9-9.9), whereas the dexmedetomidine group had the lowest (OR, 0.7; 95% CI, 0.2-1.8), compared with the local anesthesia group. Surgical time was shortest with dexmedetomidine (mean, 283 minutes) and longest with local anesthesia only (mean, 328 minutes). Functional outcome (Unified Parkinson's Disease Rating Scale, Part III motor component scale) was similar among groups. The dexmedetomidine group had a statistically significant lower risk of perioperative neurologic events compared with the local anesthesia group (OR, 0.09; 95% CI, 0.002-0.68).

CONCLUSIONS

Sedation can be used safely without affecting outcome, and dexmedetomidine provides better hemodynamic management. Clinical significance remains unclear and larger studies need to be undertaken.

Complications of Deep Brain Stimulation (DBS) for dystonia in children - The challenges and 10 year experience in a large paediatric cohort

Deep brain stimulation (DBS) has been increasingly used for primary and secondary movement disorders in children and young people. Reports of hardware related complications have been sparse for this population and from small cohorts of patients. We report DBS complications from a single large DBS centre with 10 year experience. Data was collected as a prospective audit and additionally from a questionnaire on recharging of the stimulators. 129 patients with a minimum 6 months follow up were identified, mean age10.8 y (range 3.0-18.75), mean follow up 3.3y (range 0.5-10.3), weight 10.4-94.2 kg, 126 new implants (92 Activa RC) and 69 revisions for reasons other than infection. 26 patients were 7y or younger. Surgical site infections (SSI) rates were 10.3% for new implants and revisions, lower 8.6% for new Activa RC and even lower, 4.7%, for new Activa RC in patients under 7y (1/21). SSI occurred within first 6 months and necessitated total system removal in 86% of those infected. Electrode/extension problems were recorded in 18.4% of patients, fracture in 4.6% malfunction in 7.7%, short extension 3.8% and electrode migration in 2.3%. Other complications involved clinically silent intracranial bleed in 1 patient, skin erosions (2.3%), unexpected switching off in 18.7% of Soletra/Kinetra and 3.4% of Activa RC, transient seroma at IPG site in postoperative period (8%). Of the 48 returned recharging questionnaires, 38% of families required recharger replacement and 23% experienced frequent problems maintaining connection during recharging. However, 83% of responders considered recharging not at all or only a little care burden. We identified lower than previously reported DBS infection rates particularly for patients under 7 years, but relatively high incidence of technical problems with electrodes, extensions and in particular recharging. This has to be considered when offering DBS for children with movement disorders.

Image-based in vivo assessment of targeting accuracy of stereotactic brain surgery in experimental rodent models

Stereotactic neurosurgery is used in pre-clinical research of neurological and psychiatric disorders in experimental rat and mouse models to engraft a needle or electrode at a pre-defined location in the brain. However, inaccurate targeting may confound the results of such experiments. In contrast to the clinical practice, inaccurate targeting in rodents remains usually unnoticed until assessed by ex vivo end-point histology. We here propose a workflow for in vivo assessment of stereotactic targeting accuracy in small animal studies based on multi-modal post-operative imaging. The surgical trajectory in each individual animal is reconstructed in 3D from the physical implant imaged in post-operative CT and/or its trace as visible in post-operative MRI. By co-registering post-operative images of individual animals to a common stereotaxic template, targeting accuracy is quantified. Two commonly used neuromodulation regions were used as targets. Target localization errors showed not only variability, but also inaccuracy in targeting. Only about 30% of electrodes were within the subnucleus structure that was targeted and a-specific adverse effects were also noted. Shifting from invasive/subjective 2D histology towards objective in vivo 3D imaging-based assessment of targeting accuracy may benefit a more effective use of the experimental data by excluding off-target cases early in the study.

High-Frequency Stimulation at the Subthalamic Nucleus Suppresses Excessive Self-Grooming in Autism-Like Mouse Models

Approximately one quarter of individuals with an autism spectrum disorder (ASD) display self-injurious behavior (SIB) ranging from head banging to self-directed biting and punching. Sometimes, these behaviors are extreme and unresponsive to pharmacological and behavioral therapies. We have found electroconvulsive therapy (ECT) can produce life-changing results, with more than 90% suppression of SIB frequency. However, these patients typically require frequent maintenance ECT (mECT), as often as every 5 days, to sustain the improvement gained during the acute course. Long-term consequences of such frequent mECT started as early as childhood in some cases are unknown. Accordingly, there is a need for alternative forms of chronic stimulation for these patients. To explore the feasibility of deep brain stimulation (DBS) for intractable SIB seen in some patients with an ASD, we utilized two genetically distinct mouse models demonstrating excessive self-grooming, namely the Viaat-Mecp2(-/y) and Shank3B(-/-) lines, and administered high-frequency stimulation (HFS) via implanted electrodes at the subthalamic nucleus (STN-HFS). We found that STN-HFS significantly suppressed excessive self-grooming in both genetic lines. Suppression occurs both acutely when stimulation is switched on, and persists for several days after HFS is stopped. This effect was not explained by a change in locomotor activity, which was unaffected by STN-HFS. Likewise, social interaction deficits were not corrected by STN-HFS. Our data show STN-HFS suppresses excessive self-grooming in two autism-like mouse models, raising the possibility DBS might be used to treat intractable SIB associated with ASDs. Further studies are required to explore the circuitry engaged by STN-HFS, as well as other potential stimulation sites. Such studies might also yield clues about pathways, which could be modulated by non-invasive stimulatory techniques.

Brainjacking: Implant Security Issues in Invasive Neuromodulation

The security of medical devices is critical to good patient care, especially when the devices are implanted. In light of recent developments in information security, there is reason to be concerned that medical implants are vulnerable to attack. The ability of attackers to exert malicious control over brain implants ("brainjacking") has unique challenges that we address in this review, with particular focus on deep brain stimulation implants. To illustrate the potential severity of this risk, we identify several mechanisms through which attackers could manipulate patients if unauthorized access to an implant can be achieved. These include blind attacks in which the attacker requires no patient-specific knowledge and targeted attacks that require patient-specific information. Blind attacks include cessation of stimulation, draining implant batteries, inducing tissue damage, and information theft. Targeted attacks include impairment of motor function, alteration of impulse control, modification of emotions or affect, induction of pain, and modulation of the reward system. We also discuss the limitations inherent in designing implants and the trade-offs that must be made to balance device security with battery life and practicality. We conclude that researchers, clinicians, manufacturers, and regulatory bodies should cooperate to minimize the risk posed by brainjacking.

Uncoupling of dopaminergic and subthalamic stimulation: Life-threatening DBS withdrawal syndrome

BACKGROUND

Deep brain stimulation (DBS) in therapy for advanced Parkinson's disease (PD) is an accepted treatment. Infections of the system and other complications occasionally result in hardware removal and subsequent medical treatment alone for months.

METHODS

We have analyzed the clinical course of 15 patients requiring removal of at least parts of the DBS system, resulting in a cessation of stimulation.

RESULTS

Most had an uncomplicated return to medical treatment. Three had an unfavorable course during withdrawal, including two deaths. These patients had suffered from PD for more than 18 y and had had DBS for more than 8 y.

CONCLUSIONS

We conclude that DBS withdrawal can be life-threatening, because the whole range of dopaminergic and nondopaminergic medical treatments may be ineffective at this stage. The lack of response to medical treatment might be attributable to advanced disease and long-term changes of the basal ganglia loop in PD.

Hospitalisation and comorbidities in Parkinson's disease: a large Australian retrospective study

OBJECTIVES

Patients with Parkinson's disease (PD) require higher levels of care during hospitalisation. Management of comorbidities in these patients aims to optimise function while minimising complications. The objective of this study was to examine patterns of hospitalisation of patients with PD in NSW with regards to sociodemographic factors, comorbidities and aspects of clinical management.

METHODS

A retrospective study of all patients with idiopathic PD and a control group of non-PD patients admitted for acute care to NSW hospitals between 2008 and 2012.

RESULTS

The study group comprised 5637 cases and 8143 controls. The mean PD patient age was 75.0 years (±10.9). Patients with PD had a significantly longer hospital stay (median 7 days, IQR 3-13 vs 1 day, IQR 1-7, p<0.001) than control patients. Patients with PD were five times more likely to be treated for delirium, three times more likely to experience an adverse drug event and syncope, more than twice as likely to require management of falls/fractures, dementia, gastrointestinal complications, genitourinary infections, reduced mobility and other trauma but half as likely to require hospitalisation for chronic airways disease and neoplasia, including melanoma, than the control group (all p<0.001).

CONCLUSIONS

Patients with PD are more likely to suffer serious health problems, including delirium, adverse drug reactions, syncope, falls and fractures than controls. These findings highlight PD as a multisystem neuropsychiatric disorder in which motor and non-motor features contribute to morbidity. Increased awareness of the added risk PD poses in acute hospitalised patients can be used to inform strategies to improve patient outcomes.

Sudden loss of the deep brain stimulation effect with high impedance without macroscopic fracture: a case report and review of the published literature

The number of deep brain stimulation (DBS) hardware complications has increased during the past decade. In cases of abnormally high lead impedance with no evidence of a macroscopic fracture, optimal treatment options have not yet been established. Here, we present the case of a 49-year-old woman with a 12-year history of Parkinson's disease who received bilateral subthalamic nucleus DBS in March 2006. The patient showed good control of parkinsonism until December 24, 2010, when she awoke with abrupt worsening of parkinsonian symptoms. At telemetric testing, lead impedances were found at >2,000 Ω in all four leads on the left side. Fracture of a lead or an extension wire was suspected. However, radiological screening and palpation revealed no macroscopic fracture. In June 2011, the implantable pulse generator (IPG) was changed under local anesthesia without any complications. Postoperatively, her parkinsonism immediately improved to the previous level, and the lead impedance readings by telemetry were also normalized. The disconnection of the neurostimulator connector block and the hybrid circuit board of the IPG was confirmed by destructive analysis. The present report illustrates that a staged approach that starts with simple IPG replacement can be an option for some cases of acute DBS effect loss with high impedance, when radiological findings are normal, thereby sparing the intact electrodes and extension wires.

Anaesthetic management of shoulder arthroscopic repair in Parkinson's disease with deep brain stimulator

We describe the anaesthetic management of arthroscopic repair for complete rotator cuff tear of shoulder in a 59-year-old female with Parkinson's disease (PD) with deep brain stimulator (DBS) using a combination of general anaesthesia with interscalene approach to brachial plexus block. The DBS consists of implanted electrodes in the brain connected to the implantable pulse generator (IPG) normally placed in the anterior chest wall subcutaneously. It can be programmed externally from a hand-held device placed directly over the battery stimulator unit. In our patient, IPG with its leads was located in close vicinity of the operative site with potential for DBS malfunction. Implications of DBS in a patient with PD for shoulder arthroscopy for anaesthesiologist are discussed along with a brief review of DBS.

Coordinate-based lead location does not predict Parkinson's disease deep brain stimulation outcome

Background

Effective target regions for deep brain stimulation (DBS) in Parkinson's disease (PD) have been well characterized. We sought to study whether the measured Cartesian coordinates of an implanted DBS lead are predictive of motor outcome(s). We tested the hypothesis that the position and trajectory of the DBS lead relative to the mid-commissural point (MCP) are significant predictors of clinical outcomes. We expected that due to neuroanatomical variation among individuals, a simple measure of the position of the DBS lead relative to MCP (commonly used in clinical practice) may not be a reliable predictor of clinical outcomes when utilized alone.

Methods

55 PD subjects implanted with subthalamic nucleus (STN) DBS and 41 subjects implanted with globus pallidus internus (GPi) DBS were included. Lead locations in AC-PC space (x, y, z coordinates of the active contact and sagittal and coronal entry angles) measured on high-resolution CT-MRI fused images, and motor outcomes (Unified Parkinson's Disease Rating Scale) were analyzed to confirm or refute a correlation between coordinate-based lead locations and DBS motor outcomes.

Results

Coordinate-based lead locations were not a significant predictor of change in UPDRS III motor scores when comparing pre- versus post-operative values. The only potentially significant individual predictor of change in UPDRS motor scores was the antero-posterior coordinate of the GPi lead (more anterior lead locations resulted in a worse outcome), but this was only a statistical trend (p<.082).

Conclusion

The results of the study showed that a simple measure of the position of the DBS lead relative to the MCP is not significantly correlated with PD motor outcomes, presumably because this method fails to account for individual neuroanatomical variability. However, there is broad agreement that motor outcomes depend strongly on lead location. The results suggest the need for more detailed identification of stimulation location relative to anatomical targets.

Surgical neuroanatomy and programming in deep brain stimulation for obsessive compulsive disorder

OBJECTIVES

Deep brain stimulation (DBS) has been established as a safe, effective therapy for movement disorders (Parkinson's disease, essential tremor, etc.), and its application is expanding to the treatment of other intractable neuropsychiatric disorders including depression and obsessive-compulsive disorder (OCD). Several published studies have supported the efficacy of DBS for severely debilitating OCD. However, questions remain regarding the optimal anatomic target and the lack of a bedside programming paradigm for OCD DBS. Management of OCD DBS can be highly variable and is typically guided by each center's individual expertise. In this paper, we review the various approaches to targeting and programming for OCD DBS. We also review the clinical experience for each proposed target and discuss the relevant neuroanatomy.

MATERIALS AND METHODS

A PubMed review was performed searching for literature on OCD DBS and included all articles published before March 2012. We included all available studies with a clear description of the anatomic targets, programming details, and the outcomes.

RESULTS

Six different DBS approaches were identified. High-frequency stimulation with high voltage was applied in most cases, and predictive factors for favorable outcomes were discussed in the literature.

CONCLUSION

DBS remains an experimental treatment for medication refractory OCD. Target selection and programming paradigms are not yet standardized, though an improved understanding of the relationship between the DBS lead and the surrounding neuroanatomic structures will aid in the selection of targets and the approach to programming. We propose to form a registry to track OCD DBS cases for future clinical study design.

Continuous perioperative apomorphine in deep brain stimulation surgery for Parkinson's disease

BACKGROUND

Patients with Parkinson's disease (PD) deprived of dopaminergic medication to facilitate awake testing during the deep brain stimulation (DBS) procedure are at increased risk of neurologic deterioration.. The aim of this survey was to demonstrate the safety of subcutaneous apomorphine treatment for reducing surgery-related neurologic deterioration in patients undergoing DBS surgery for PD.

METHODS

Ninety-two patients who underwent DBS surgery for PD between 11/2007 and 10/2011 in our department were retrospectively analyzed for this survey. Demographic data, apomorphine dosage, side-effects and need of ICU/IMC stay were collected and analyzed.

RESULTS

Seventy-two out of 92 patients (78.3%) received apomorphine treatment; main reason for omission of treatment was intolerable nausea (16/92, 17.3%). Apomorphine treatment was well tolerated and the most common side effect was nodular panniculitis. No severe complications were observed. No patient required ICU/IMC stay related to dopaminergic deprivation.

CONCLUSIONS

Perioperative withdrawal of dopaminergic medication in PD patients leads to an increased risk of neurologic and respiratory deterioration during DBS procedures. These complications can likely be tempered using perioperative subcutaneous apomorphine as a substitute. Our 5-year experience indicates a reduction in postoperative neurologic deterioration and ICU/IMC stay need. We consider perioperative apomorphine safe during DBS surgery for PD.

Unilateral thalamic deep brain stimulation in essential tremor demonstrates long-term ipsilateral effects

INTRODUCTION

Deep Brain Stimulation (DBS) of thalamus in essential tremor (ET) is effective for the treatment of contralateral tremors. Bilateral DBS controls tremors on both sides but is associated with increased morbidity and risks. We evaluated if unilateral surgery had ipsilateral benefits on tremors and thus could be a potentially safer alternative to bilateral DBS.

METHODS

Medication refractory ET patients undergoing unilateral thalamic DBS were included and longitudinally followed. Tremor rating scale was used to record total motor, arm tremor and activities of daily living (ADL) scores at baseline, six months and at last visit (three or more years after surgery). Postoperative scores were recorded with DBS turned OFF and ON.

RESULTS

Twenty-two patients with a mean follow-up 3.4 ± 0.14 years were enrolled. When baseline scores were compared to scores with the DBS turned ON, significant improvements were noted in total tremor (40%), ADL (67%) and arm tremor scores both on the ipsilateral and the contralateral side at six months and at the last visit of follow-up (all p < 0.05). Ipsilateral arm tremor (∼56%) improvements were milder compared to the contralateral side (∼73%) tremors.

CONCLUSION

Unilateral thalamic DBS in ET demonstrates significant long-term benefits for ipsilateral arm tremors and can be offered to higher risk and to select patients.

Chronological changes in astrocytes induced by chronic electrical sensorimotor cortex stimulation in rats

Motor cortex stimulation (MCS) is a treatment option for various disorders such as medically refractory pain, poststroke hemiplegia, and movement disorders. However, the exact mechanisms underlying its effects remain unknown. In this study, the effects of long-term chronic MCS were investigated by observing changes in astrocytes. A quadripolar stimulation electrode was implanted on the dura over the sensorimotor cortex of adult rats, and the cortex was continuously stimulated for 3 hours, 1 week, 4 weeks, and 8 weeks. Immunohistochemical staining of microglia (ionized calcium-binding adaptor molecule 1 [Iba1] staining) and astrocytes (glial fibrillary acidic protein [GFAP] staining), and neuronal degeneration histochemistry (Fluoro-Jade B staining) were carried out to investigate the morphological changes following long-term chronic MCS. Iba1 staining and Fluoro-Jade B staining showed no evidence of Iba1-positive microglial changes or neurodegeneration. Following continuous MCS, GFAP-positive astrocytes were enlarged and their number increased in the cortex and the thalamus of the stimulated hemisphere. These findings indicate that chronic electrical stimulation can continuously activate astrocytes and result in morphological and quantitative changes. These changes may be involved in the mechanisms underlying the neuroplasticity effect induced by MCS.

Cerebral venous infarction: a potentially avoidable complication of deep brain stimulation surgery

OBJECT

Despite numerous reports on the morbidity and mortality of deep brain stimulation (DBS), cerebral venous infarction has rarely been reported. We present four cases of venous infarct secondary to DBS surgery.

METHODS

The diagnosis of venous infarction was based on 1) delayed onset of new neurologic deficits on postoperative day 1 or 2; 2) significant edema surrounding the superficial aspect of the implanted lead, with or without subcortical hemorrhage on CT scan.

RESULTS

Four cases (0.8% per lead, 1.3% per patient) of symptomatic cerebral venous infarction were identified out of 500 DBS lead implantation procedures between July 2002 and August 2009. All four patients had Parkinson's disease. Their DBS leads were implanted in the subthalamic nucleus (n = 2), and the globus pallidus internus (n = 2). Retrospective review of the targeting confirmed that the planned trajectory passed within 3 mm of a cortical vein in two cases for which contrast-enhanced preoperative magnetic resonance (MR) imaging was available. In the other two cases, contrasted targeting images were not obtained preoperatively.

CONCLUSION

Cerebral venous infarction is a potentially avoidable, but serious complication. To minimize its incidence, we propose the use of high-resolution, contrast-enhanced, T1-weighted MR images to delineate cerebral venous anatomy, along with careful stereotactic planning of the lead trajectory to avoid injury to venous structures.

Active exercise for individuals with cervical dystonia: a pilot randomized controlled trial

Objective:

To investigate the feasibility and effectiveness of an active exercise program for cervical dystonia.

Design:

Pilot randomized controlled, single-blind trial of a 12-week intervention followed by a four-week follow-up period.

Setting:

Supervised physiotherapy and outcome measurement sessions were conducted in a hospital outpatient physiotherapy setting. Participants also performed exercises at home.

Subjects:

Twenty participants with idiopathic cervical dystonia were randomized into an experimental ( n = 9) or control ( n = 11) group. Two participants from the experimental group and one from the control group dropped out.

Interventions:

The experimental group undertook a semi-supervised active exercise program aimed at correcting the dystonic head position, plus relaxation. The control group performed relaxation only.

Main outcome measures:

Feasibility of the intervention was assessed by recording adherence, muscle soreness, and adverse events. The primary outcome measure was blinded analysis of the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) score.

Results:

The active exercise program was feasible and safe, with participants in the experimental group completing 84% of prescribed training sessions in the 12-week intervention period. There were no adverse events in either group, while mild muscle soreness was reported by 66% of the experimental group. There was no significant difference between groups at post-test or follow-up. The difference between groups of −1.9 (95% confidence interval (CI) –9.0–5.2) on the TWSTRS demonstrates a trend towards greater improvement for the experimental group.

Conclusion:

Active exercise for people with cervical dystonia is feasible and can be completed with good adherence and no adverse effects.

Postmortem observation of collagenous lead tip region fibrosis as a rare complication of DBS

BACKGROUND

Despite the widespread effective use of deep brain stimulation (DBS) for various movement and psychiatric disorders, little is known about its safety and tissue responses.

METHODS

The University of Florida Deep Brain Stimulation Brain Tissue Network (DBS-BTN) conducted postmortem brain examinations on 26 cases to identify and characterize (using histological techniques) pathologic tissue changes associated with the placement of DBS devices.

RESULTS

We report the unusual finding of prominent collagenous fibrosis around the lead tip in a 74-year-old man with idiopathic Parkinson's disease who had bilateral STN-DBS. Histological study confirmed the diagnosis of idiopathic Parkinson's disease, and there was striking, dense collagenous fibrosis at the distal end of the right DBS lead associated with focal hemosiderin deposition, chronic inflammation, and mild gliosis. We have in our brain bank 25 other DBS cases that on examination showed only mild to moderate gliosis and no dramatic tissue response to DBS lead placement.

CONCLUSIONS

We are not aware of any prior reports of such a dramatic reaction to DBS placement to date.

Diagnosis and treatment of complications related to deep brain stimulation hardware

Deep brain stimulation is a therapeutic technique increasingly used in the treatment of a variety of neurological, psychiatric, and pain disorders. Although beneficial, it carries the immediate and long-term risks associated with implanted hardware in the brain parenchyma and subcutaneous tissue. The most common hardware complications include electrode migrations or misplacements, wire fractures, skin erosion, infections, and device malfunction. We systematically reviewed the literature on deep brain stimulation-related complications and propose a diagnostic and therapeutic algorithm. Our aim is to provide a guide for clinicians and medical staff involved in the treatment of patients with deep brain stimulation for rapid recognition and efficient management of these complications.

Management of the hospitalized patient with Parkinson's disease: current state of the field and need for guidelines

OBJECTIVE

To review the literature and to identify practice gaps in the management of the hospitalized Parkinson's disease (PD) patient.

BACKGROUND

Patients with PD are admitted to hospitals at higher rates, and frequently have longer hospital stays than the general population. Little is known about outpatient interventions that might reduce the need for hospitalization and also reduce hospital-related complications.

METHODS

A literature review was performed on PubMed about hospitalization and PD between 1970 and 2010. In addition, in press peer-reviewed papers or published abstracts known to the authors were included. Information was reviewed by a National Parkinson Foundation workgroup and a narrative review article was generated.

RESULTS

Motor disturbances in PD are believed to be a causal factor in the higher rates of admissions and complications. However, other conditions are commonly recorded as the primary reason for hospitalization including motor complications, reduced mobility, lack of compliance, inappropriate use of neuroleptics, falls, fractures, pneumonia, and other important medical problems. There are many relevant issues related to hospitalization in PD. Medications, dosages and specific dosage schedules are critical. Staff training regarding medications and medication management may help to avoid complications, particularly those related to reduced mobility, and aspiration pneumonia. Treatment of infections and a return to early mobility is also critical to management.

CONCLUSIONS

Educational programs, recommendations, and guidelines are needed to better train interdisciplinary teams in the management of the PD patient. These initiatives have the potential for both cost savings and improved outcomes from a preventative and a hospital management standpoint.

From the cell to the clinic: a comparative review of the partial D₂/D₃receptor agonist and α2-adrenoceptor antagonist, piribedil, in the treatment of Parkinson's disease

Though L-3,4-dihydroxyphenylalanine (L-DOPA) is universally employed for alleviation of motor dysfunction in Parkinson's disease (PD), it is poorly-effective against co-morbid symptoms like cognitive impairment and depression. Further, it elicits dyskinesia, its pharmacokinetics are highly variable, and efficacy wanes upon long-term administration. Accordingly, "dopaminergic agonists" are increasingly employed both as adjuncts to L-DOPA and as monotherapy. While all recognize dopamine D(2) receptors, they display contrasting patterns of interaction with other classes of monoaminergic receptor. For example, pramipexole and ropinirole are high efficacy agonists at D(2) and D(3) receptors, while pergolide recognizes D(1), D(2) and D(3) receptors and a broad suite of serotonergic receptors. Interestingly, several antiparkinson drugs display modest efficacy at D(2) receptors. Of these, piribedil displays the unique cellular signature of: 1), signal-specific partial agonist actions at dopamine D(2)and D(3) receptors; 2), antagonist properties at α(2)-adrenoceptors and 3), minimal interaction with serotonergic receptors. Dopamine-deprived striatal D(2) receptors are supersensitive in PD, so partial agonism is sufficient for relief of motor dysfunction while limiting undesirable effects due to "over-dosage" of "normosensitive" D(2) receptors elsewhere. Further, α(2)-adrenoceptor antagonism reinforces adrenergic, dopaminergic and cholinergic transmission to favourably influence motor function, cognition, mood and the integrity of dopaminergic neurones. In reviewing the above issues, the present paper focuses on the distinctive cellular, preclinical and therapeutic profile of piribedil, comparisons to pramipexole, ropinirole and pergolide, and the core triad of symptoms that characterises PD-motor dysfunction, depressed mood and cognitive impairment. The article concludes by highlighting perspectives for clarifying the mechanisms of action of piribedil and other antiparkinson agents, and for optimizing their clinical exploitation.