Deep brain stimulation of the subthalamic nucleus for the treatment of Parkinson's disease

Neurosurgery in Parkinson's disease: Social adjustment, quality of life and coping strategies

Subthalamic nucleus deep brain stimulation has become a standard neurosurgical therapy for advanced Parkinson's disease. Subthalamic nucleus deep brain stimulation can dramatically improve the motor symptoms of carefully selected patients with this disease. Surprisingly, some specific dimensions of quality of life, “psychological” aspects and social adjustment do not always improve, and they could sometimes be even worse. Patients and their families should fully understand that subthalamic nucleus deep brain stimulation can alter the motor status and time is needed to readapt to their new postoperative state and lifestyles. This paper reviews the literatures regarding effects of bilateral subthalamic nucleus deep brain stimulation on social adjustment, quality of life and coping strategies in patients with Parkinson's disease. The findings may help to understand the psychosocial maladjustment and poor improvement in quality of life in some Parkinson's disease patients.

Development of the Mayo Investigational Neuromodulation Control System: toward a closed-loop electrochemical feedback system for deep brain stimulation

OBJECT

Conventional deep brain stimulation (DBS) devices continue to rely on an open-loop system in which stimulation is independent of functional neural feedback. The authors previously proposed that as the foundation of a DBS "smart" device, a closed-loop system based on neurochemical feedback, may have the potential to improve therapeutic outcomes. Alterations in neurochemical release are thought to be linked to the clinical benefit of DBS, and fast-scan cyclic voltammetry (FSCV) has been shown to be effective for recording these evoked neurochemical changes. However, the combination of FSCV with conventional DBS devices interferes with the recording and identification of the evoked analytes. To integrate neurochemical recording with neurostimulation, the authors developed the Mayo Investigational Neuromodulation Control System (MINCS), a novel, wirelessly controlled stimulation device designed to interface with FSCV performed by their previously described Wireless Instantaneous Neurochemical Concentration Sensing System (WINCS).

METHODS

To test the functionality of these integrated devices, various frequencies of electrical stimulation were applied by MINCS to the medial forebrain bundle of the anesthetized rat, and striatal dopamine release was recorded by WINCS. The parameters for FSCV in the present study consisted of a pyramidal voltage waveform applied to the carbon-fiber microelectrode every 100 msec, ramping between -0.4 V and +1.5 V with respect to an Ag/AgCl reference electrode at a scan rate of either 400 V/sec or 1000 V/sec. The carbon-fiber microelectrode was held at the baseline potential of -0.4 V between scans.

RESULTS

By using MINCS in conjunction with WINCS coordinated through an optic fiber, the authors interleaved intervals of electrical stimulation with FSCV scans and thus obtained artifact-free wireless FSCV recordings. Electrical stimulation of the medial forebrain bundle in the anesthetized rat by MINCS elicited striatal dopamine release that was time-locked to stimulation and increased progressively with stimulation frequency.

CONCLUSIONS

Here, the authors report a series of proof-of-principle tests in the rat brain demonstrating MINCS to be a reliable and flexible stimulation device that, when used in conjunction with WINCS, performs wirelessly controlled stimulation concurrent with artifact-free neurochemical recording. These findings suggest that the integration of neurochemical recording with neurostimulation may be a useful first step toward the development of a closed-loop DBS system for human application.

A numerical study to compare stimulations by intraoperative microelectrodes and chronic macroelectrodes in the DBS technique

Deep brain stimulation is a clinical technique for the treatment of parkinson's disease based on the electric stimulation, through an implanted electrode, of specific basal ganglia in the brain. To identify the correct target of stimulation and to choose the optimal parameters for the stimulating signal, intraoperative microelectrodes are generally used. However, when they are replaced with the chronic macroelectrode, the effect of the stimulation is often very different. Here, we used numerical simulations to predict the stimulation of neuronal fibers induced by microelectrodes and macroelectrodes placed in different positions with respect to each other. Results indicate that comparable stimulations can be obtained if the chronic macroelectrode is correctly positioned with the same electric center of the intraoperative microelectrode. Otherwise, some groups of fibers may experience a completely different electric stimulation.

Parkin mutation and deep brain stimulation outcome

Patients with parkin mutations are expected to be good candidates for deep brain stimulation (DBS) because of an excellent levodopa response and frequent occurrence of levodopa-induced dyskinesia. However, there are insufficient data on surgical outcome in patients with parkin mutations. This study aimed to compare the outcome of subthalamic nucleus DBS in patients with early-onset Parkinson's disease with and without parkin mutations. Fourteen patients with early-onset Parkinson's disease who underwent bilateral subthalamic nucleus DBS surgery were screened for parkin mutations and assessed for surgical outcomes at baseline and 2-5years after surgery. Three patients had homozygote/compound heterozygote mutations; two had single heterozygote mutations; and nine had no mutations. Patients with homozygote/compound heterozygote mutations were younger at disease onset and had longer disease duration than patients without a parkin mutation. Postoperatively, there were no significant differences in improvement on the Unified Parkinson's Disease Rating Scale part II, III, and IV, or the reduction of levodopa equivalent daily doses between patients with and without parkin mutations. The therapeutic effect of DBS did not differ between patients with and without parkin mutations.

Current challenges to the clinical translation of brain machine interface technology

Development of neural prostheses over the past few decades has produced a number of clinically relevant brain-machine interfaces (BMIs), such as the cochlear prostheses and deep brain stimulators. Current research pursues the restoration of communication or motor function to individuals with neurological disorders. Efforts in the field, such as the BrainGate trials, have already demonstrated that such interfaces can enable humans to effectively control external devices with neural signals. However, a number of significant issues regarding BMI performance, device capabilities, and surgery must be resolved before clinical use of BMI technology can become widespread. This chapter reviews challenges to clinical translation and discusses potential solutions that have been reported in recent literature, with focuses on hardware reliability, state-of-the-art decoding algorithms, and surgical considerations during implantation.

Stimulation sites in the subthalamic nucleus projected onto a mean 3-D atlas of the thalamus and basal ganglia

BACKGROUND

In patients with severe forms of Parkinson's disease (PD), deep brain stimulation (DBS) commonly targets the subthalamic nucleus (STN). Recently, the mean 3-D Morel-Atlas of the basal ganglia and the thalamus was introduced. It combines information contained in histological data from ten post-mortem brains. We were interested whether the Morel-Atlas is applicable for the visualization of stimulation sites.

METHODS

In a consecutive PD patient series, we documented preoperative MRI planning, intraoperative target adjustment based on electrophysiological and neurological testing, and perioperative CT target reconstruction. The localization of the DBS electrodes and the optimal stimulation sites were projected onto the Morel-Atlas.

RESULTS

We included 20 patients (median age 62 years). The active contact had mean coordinates Xlat = ±12.1 mm, Yap = -1.8 mm, Zvert = -3.2 mm. There was a significant difference between the initially planned site and the coordinates of the postoperative active contact site (median 2.2 mm). The stimulation site was, on average, more anterior and more dorsal. The electrode contact used for optimal stimulation was found within the STN of the atlas in 38/40 (95 %) of implantations.

CONCLUSIONS

The cluster of stimulation sites in individual patients-as deduced from preoperative MR, intraoperative electrophysiology and neurological testing-showed a high degree of congruence with the atlas. The mean 3D Morel Atlas is thus a useful tool for postoperative target visualization. This represents the first clinical evaluation of the recently created atlas.

The Anatomical and Electrophysiological Subthalamic Nucleus Visualized by 3-T Magnetic Resonance Imaging

BACKGROUND:

Accurate localization of the subthalamic nucleus (STN) is critical to the success of deep brain stimulation surgery for Parkinson disease. Recent developments in high-field-strength magnetic resonance imaging (MRI) have made it possible to visualize the STN in greater detail. However, the relationship of the MR-visualized STN to the anatomic, electrophysiological, or atlas-predicted STN remains controversial.

OBJECTIVE:

To evaluate the size of the STN visualized on 3-T MRI compared with anatomic measurements in cadaver studies and to compare the predictions of 3-T MRI and those of the Schaltenbrand-Wahren (SW) atlas for intraoperative STN microelectrode recordings.

METHODS:

We evaluated the STN by 3-T MRI and intraoperative microelectrode recordings in 20 Parkinson disease patients undergoing deep brain stimulation surgery. We compared our findings with anatomic cadaver studies and with the individually scaled SW atlas-based predictions for each patient.

RESULTS:

The dimensions of the 3-T MR-visualized STN were very similar to those of the largest anatomic study (MRI length, width, and height: 9.8 ± 1.6, 11.5 ± 1.6, and 3.7 ± 0.7 mm, respectively; n = 40; cadaver length, width, and height: 9.3 ± 0.7, 10.6 ± 0.9, and 3.1 ± 0.5 mm, respectively; n = 100). The amount of STN traversed during intraoperative microelectrode recordings was better correlated to the 3-T MR-visualized STN than the SW atlas-predicted STN (R = 0.38 vs R = −0.17).

CONCLUSION:

The STN as visualized on 3-T MRI corresponds well with cadaveric anatomic studies and intraoperative electrophysiology. STN visualization with 3-T MRI may be an improvement over SW atlas-based localization for STN deep brain stimulation surgery in Parkinson disease.

Factors related to outcomes of subthalamic deep brain stimulation in Parkinson's disease

OBJECTIVE

Subthalamic nucleus (STN) deep brain stimulation (DBS) is an effective treatment of choice for patients with advanced idiopathic Parkinson's disease (PD) who have motor complication with medication. The objectives of this study are to analyze long-term follow-up data of STN DBS cases and to identify the factors related to outcomes.

METHODS

Fifty-two PD patients who underwent STN DBS were followed-up for more than 3 years. The Unified Parkinsons Disease Rating Scale (UPDRS) and other clinical profiles were assessed preoperatively and during follow-up. A linear regression model was used to analyze whether factors predict the results of STN DBS. We divided the study individuals into subgroups according to several factors and compared subgroups.

RESULTS

Preoperative activity of daily living (ADL) and the magnitude of preoperative levodopa response were shown to predict the improvement in UPDRS part II without medication, and preoperative ADL and levodopa equivalent dose (LED) were shown to predict the improvement in UPDRS part II with medication. In UPDRS part III with medication, the magnitude of preoperative levodopa response was a predicting factor.

CONCLUSION

The intensity of preoperative levodopa response was a strong factor for motor outcome. And preoperative ADL and LED were strong factors for ADL improvement. More vigorous studies should be conducted to elucidate how levodopa-induced motor complications are ameliorated after STN DBS.

Lack of differential motor outcome with subthalamic nucleus region stimulation in Parkinson's disease

Deep brain stimulation (DBS) has emerged as a viable therapy for Parkinson's disease (PD). The impact of subthalamic nucleus (STN) lead placement (lateral versus medial) on motor outcome, however, has not been systematically evaluated. Forty-eight patients with PD underwent STN-DBS surgery and were evaluated postoperatively for 48 weeks for motor improvement as measured by the Unified Parkinson's Disease Rating Scale (UPDRS) part III (standardized motor examination) and levodopa equivalent daily dose (LEDD). Postoperative MRI was used to identify the location of the active stimulating contact and motor outcome was analyzed. STN-DBS was associated with significant improvement in motor outcome as determined by a reduction in the UPDRS part III subscore from 34.44 ± 1.29 at baseline to 18.76 ± 1.06 at end visit (p<0.0001) and a reduction in LEDD from 1721 ± 152 mg/day at baseline to 1134 ± 119 mg/day at end visit (p=0.0024). Patients with stimulating contacts in the medial STN compared to the lateral STN did not demonstrate any significant differences in motor outcome (UPDRS, p=0.5811; LEDD, p=0.7341). No significant differences were found in motor outcome between patients with STN stimulation compared to stimulation of surrounding fiber tracts (p=0.80). No significant difference in stimulation voltage was noted with respect to lead location. Our study did not find a significant effect for the location of active contact and motor outcome neither within the subregions of the STN nor between the STN and surrounding fibers. Further research is needed to better understand the neurophysiological basis for these results.

Functional and effective connectivity in subthalamic local field potential recordings of patients with Parkinson's disease

In Parkinson's disease (PD) levodopa-associated changes in the power and long-range temporal correlations of beta oscillations have been demonstrated, yet the presence and modulation of genuine connectivity in local field potentials (LFP) recorded from the subthalamic nucleus (STN) remains an open question. The present study investigated LFP recorded bilaterally from the STN at wakeful rest in ten patients with PD after overnight withdrawal of levodopa (OFF) and after a single dose levodopa administration (ON). We utilized connectivity measures being insensitive to volume conduction (functional connectivity: non-zero imaginary part of coherency; effective connectivity: phase-slope index). We demonstrated the presence of neuronal interactions in the frequency range of 10-30 Hz in STN-LFP without a preferential directionality of interactions between different contacts along the electrode tracks. While the direction of neuronal interactions per se was preserved after levodopa administration, functional connectivity and the ventral-dorsal information flow were modulated by medication. The OFF-ON differences in functional connectivity were correlated with the levodopa-induced improvement in clinical Unified Parkinson's Disease Rating Scale scores. We hypothesize that regional neuronal interactions, as reflected in STN-LFP connectivity, might represent a basis for the intra-nuclear spatial specificity of deep brain stimulation. Moreover, our results suggest the potential use of volume conduction-insensitive measures of connectivity in STN-LFP as a marker of clinical motor symptoms in PD.

Resident adult neural stem cells in Parkinson's disease--the brain's own repair system?

One important pathological process in the brain of Parkinson disease (PD) patients is the degeneration of the dopaminergic neurons in the substantia nigra, which leads to a decline in striatal dopamine levels and motor dysfunction. A major clinical problem is that this degenerative process currently cannot be stopped or reversed. Expectations from the restorative capacity of neural stem cells (NSCs) are high, as these cells can potentially replace the degenerating neurons. The discovery of the presence of NSCs in the adult human brain has instigated research into the potential of these cells as a resource to promote brain repair in neurodegenerative diseases. Neural stem and progenitor cells reside in the subventricular zone (SVZ), which is closely situated to the striatum, which is affected in PD. Therefore, restoring the dopamine levels in the striatum of PD patients through stimulating endogenous NSCs in the nearby SVZ to migrate into the striatum and differentiate into dopaminergic neurons might thus be an attractive future therapeutic approach. We will review the reported changes in NSCs in the SVZ of PD animal models and PD patients, which are due to a lack of striatal dopamine. Furthermore, we will summarise the reports that describe efforts to stimulate NSCs to replace dopaminergic cells in the SN and restore striatal dopamine levels. In our opinion, mobilizing the endogenous SVZ NSCs to replenish striatal dopamine is an attractive approach to alleviate the motor symptoms in PD patients, without the ethical and immunological challenges of transplantation of NSCs and foetal brain tissue.

Adaptive deep brain stimulation in advanced Parkinson disease

OBJECTIVE

Brain-computer interfaces (BCIs) could potentially be used to interact with pathological brain signals to intervene and ameliorate their effects in disease states. Here, we provide proof-of-principle of this approach by using a BCI to interpret pathological brain activity in patients with advanced Parkinson disease (PD) and to use this feedback to control when therapeutic deep brain stimulation (DBS) is delivered. Our goal was to demonstrate that by personalizing and optimizing stimulation in real time, we could improve on both the efficacy and efficiency of conventional continuous DBS.

METHODS

We tested BCI-controlled adaptive DBS (aDBS) of the subthalamic nucleus in 8 PD patients. Feedback was provided by processing of the local field potentials recorded directly from the stimulation electrodes. The results were compared to no stimulation, conventional continuous stimulation (cDBS), and random intermittent stimulation. Both unblinded and blinded clinical assessments of motor effect were performed using the Unified Parkinson's Disease Rating Scale.

RESULTS

Motor scores improved by 66% (unblinded) and 50% (blinded) during aDBS, which were 29% (p = 0.03) and 27% (p = 0.005) better than cDBS, respectively. These improvements were achieved with a 56% reduction in stimulation time compared to cDBS, and a corresponding reduction in energy requirements (p < 0.001). aDBS was also more effective than no stimulation and random intermittent stimulation.

INTERPRETATION

BCI-controlled DBS is tractable and can be more efficient and efficacious than conventional continuous neuromodulation for PD.

The MDS-UPDRS tracks motor and non-motor improvement due to subthalamic nucleus deep brain stimulation in Parkinson disease

BACKGROUND

The Movement Disorders Society revision of the Unified Parkinson Disease Rating Scale (MDS-UPDRS) improves upon the original UPDRS by adding more non-motor items, making it a more robust tool to evaluate the severity of motor and non-motor symptoms of Parkinson disease. Previous studies on deep brain stimulation have not used the MDS-UPDRS.

OBJECTIVE

To determine if the MDS-UPDRS could detect improvement in both motor and non-motor symptoms after bilateral subthalamic nucleus deep brain stimulation for Parkinson disease.

METHODS

We compared scores on the entire MDS-UPDRS prior to surgery (baseline) and approximately six months following the initial programming visit in twenty subjects (12M/8F) with Parkinson disease undergoing bilateral subthalamic nucleus deep brain stimulation.

RESULTS

STN DBS significantly improved the scores for every section of the MDS-UPDRS at the 6 month follow-up. Part I improved by 3.1 points (22%), Part II by 5.3 points (29%), Part III by 13.1 points (29%) with stimulation alone, and Part IV by 7.1 points (74%). Individual non-motor items in Part I that improved significantly were constipation, light-headedness, and fatigue.

CONCLUSIONS

Both motor and non-motor symptoms, as assessed by the MDS-UPDRS, improve with bilateral subthalamic nucleus stimulation six months after the stimulator is turned on. We recommend that the MDS-UPDRS be utilized in future deep brain stimulation studies because of the advantage of detecting change in non-motor symptoms.

The serendipity case of the pedunculopontine nucleus low-frequency brain stimulation: chasing a gait response, finding sleep, and cognition improvement

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an efficacious therapy for Parkinson’s disease (PD) but its effects on non-motor facets may be detrimental. The low-frequency stimulation (LFS) of the pedunculopontine nucleus (PPN or the nucleus tegmenti pedunculopontini – PPTg-) opened new perspectives. In our hands, PPTg-LFS revealed a modest influence on gait but increased sleep quality and degree of attentiveness. At odds with potential adverse events following STN-DBS, executive functions, under PPTg-ON, ameliorated. A recent study comparing both targets found that only PPTg-LFS improved night-time sleep and daytime sleepiness. Chances are that different neurosurgical groups influence either the PPN sub-portion identified as pars dissipata (more interconnected with GPi/STN) or the caudal PPN region known as pars compacta, preferentially targeting intralaminar and associative nucleus of the thalamus. Yet, the wide electrical field delivered affects a plethora of en passant circuits, and a fine distinction on the specific pathways involved is elusive. This review explores our angle of vision, by which PPTg-LFS activates cholinergic and glutamatergic ascending fibers, influencing non-motor behaviors.

Improved subthalamic nucleus depiction with quantitative susceptibility mapping

PURPOSE

To assess quantitative susceptibility mapping (QSM) in the depiction of the subthalamic nucleus (STN) by using 3-T magnetic resonance (MR) imaging.

MATERIALS AND METHODS

This study was HIPAA compliant and institutional review board approved. Ten healthy subjects (five men, five women; mean age, 24 years ± 3 [standard deviation]; age range, 21-33 years) and eight patients with Parkinson disease (five men, three women; mean age, 57 years ± 14; age range, 25-69 years) who were referred by neurologists for preoperative navigation MR imaging prior to deep brain stimulator placement were included in this study. T2-weighted (T2w), T2*-weighted (T2*w), R2* mapping (R2*), phase, susceptibility-weighted (SW), and QSM images were reconstructed for STN depiction. Qualitative visualization scores of STN and internal globus pallidus (GPi) were recorded by two neuroradiologists on all images. Contrast-to-noise ratios (CNRs) of the STN and GPi were also measured. Measurement differences were assessed by using the Wilcoxon rank sum test and the signed rank test.

RESULTS

Qualitative scores were significantly higher on QSM images than on T2w, T2*w, R2*, phase, or SW images (P < .05) for STN and GPi visualization. Median CNR was 6.4 and 10.7 times higher on QSM images than on T2w images for differentiation of STN from the zona incerta and substantia nigra, respectively, and was 22.7 and 9.1 times higher on QSM images than on T2w images for differentiation of GPi from the internal capsule and external globus pallidus, respectively. CNR differences between QSM images and all other images were significant (P < .01).

CONCLUSION

QSM at 3-T MR imaging performs significantly better than current standard-of-care sequences in the depiction of the STN.

Neurologist consistency in interpreting information provided by an interactive visualization software for deep brain stimulation postoperative programming assistance

INTRODUCTION

Postoperative programming in deep brain stimulation (DBS) therapy for movement disorders can be challenging and time consuming. Providing the neurologist with tools to visualize the electrode location relative to the patient's anatomy along with models of tissue activation and statistical data can therefore be very helpful. In this study, we evaluate the consistency between neurologists in interpreting and using such information provided by our DBS programming assistance software.

METHODS

Five neurologists experienced in DBS programming were each given a dataset of 29 leads implanted in 17 patients. For each patient, probabilistic maps of stimulation response, anatomical images, models of tissue activation volumes, and electrode positions were presented inside a software framework called CRAnialVault Explorer (CRAVE) developed in house. Consistency between neurologists in optimal contact selection using the software was measured.

RESULTS

With only the efficacy map, the average consistency among the five neurologists with respect to the mode and mean of their selections was 97% and 95%, respectively, while these numbers were 93% and 89%, respectively, when both efficacy and an adverse effect map were used simultaneously. Fleiss' kappa statistic also showed very strong agreement among the neurologists (0.87 when using one map and 0.72 when using two maps).

CONCLUSION

Our five neurologists demonstrated high consistency in interpreting information provided by the CRAVE interactive visualization software for DBS postoperative programming assistance. Three of our five neurologists had no prior experience with the software, which suggests that the software has a short learning curve and contact selection is not dependent on familiarity with the program tools.

Intracerebral quantitative chromophore estimation from reflectance spectra captured during deep brain stimulation implantation

Quantification of blood fraction (f(blood)), blood oxygenation (S(O2)), melanin, lipofuscin and oxidised and reduced Cytochrome aa 3 and c was done from diffuse reflectance spectra captured in cortex, white matter, globus pallidus internus (GPi) and subthalamus during stereotactic implantations of 29 deep brain stimulation (DBS) electrodes with the aim of investigating whether the chromophores can give physiological information about the targets for DBS. Double-sided Mann-Whitney U-tests showed more lipofuscin in GPi compared to white matter and subthalamus (p < 0.05). Compared to the other structures, f(blood) was significantly higher in cortex (p < 0.05) and S(O2) lower in GPi (p < 0.05). Median values and range for f(blood) were 1.0 [0.2-6.0]% in the cortex, 0.3 [0.1-8.2]% in white matter, 0.2 [0.1-0.8]% in the GPi and 0.2 [0.1-11.7]% in the subthalamus. Corresponding values for S(O2) was 20 [0-81]% in the cortex, 29 [0-78]% in white matter, 0 [0-0]% in the GPi and 0 [0-92]% in the subthalamus. In conclusion, the measurements indicate very low oxygenation and blood volume for DBS patients, especially in the GPi. It would be of great interest to investigate whether this is due to the disease, the normal situation or an artefact of doing invasive measurements.

Neuronal activity correlated with checking behaviour in the subthalamic nucleus of patients with obsessive-compulsive disorder

Doubt, and its behavioural correlate, checking, is a normal phenomenon of human cognition that is dramatically exacerbated in obsessive-compulsive disorder. We recently showed that deep brain stimulation in the associative-limbic area of the subthalamic nucleus, a central core of the basal ganglia, improved obsessive-compulsive disorder. To understand the physiological bases of symptoms in such patients, we recorded the activity of individual neurons in the therapeutic target during surgery while subjects performed a cognitive task that gave them the possibility of unrestricted repetitive checking after they had made a choice. We postulated that the activity of neurons in this region could be influenced by doubt and checking behaviour. Among the 63/87 task-related neurons recorded in 10 patients, 60% responded to various combinations of instructions, delay, movement or feedback, thus highlighting their role in the integration of different types of information. In addition, task-related activity directed towards decision-making increased during trials with checking in comparison with those without checking. These results suggest that the associative-limbic subthalamic nucleus plays a role in doubt-related repetitive thoughts. Overall, our results not only provide new insight into the role of the subthalamic nucleus in human cognition but also support the fact that subthalamic nucleus modulation by deep brain stimulation reduced compulsive behaviour in patients with obsessive-compulsive disorder.

Morphological and chemical analysis of a deep brain stimulation electrode explanted from a dystonic patient

Deep brain stimulation is an effective treatment for different types of dystonia; nevertheless dystonic movements could provoke hardware-related complications, including fractures or electrodes displacement. This study focuses on a morphological and structural analysis of a malfunctioning electrode removed from a dystonic patient. In this case, high impedance values and worsening of symptoms were observed. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) were performed on the explanted electrode. The qualitative and quantitative data collected from the damaged electrode were compared with a new electrode, used as a control. The SEM analysis of the damaged electrode revealed fissurations and crack-like forms of the outer jacket tubing, degeneration of the internal core and wires stretching. The EDX analysis permitted to appreciate an increase of chemical elements, especially sodium, suggesting an alteration of the electrode-brain interface. This study shows the qualitative and quantitative alterations of a malfunctioning electrode and, to reduce the rate of hardware-related complications, it suggests the development of more reliable polymers.

Striatal molecular signature of subchronic subthalamic nucleus high frequency stimulation in parkinsonian rat

This study addresses the molecular mechanisms underlying the action of subthalamic nucleus high frequency stimulation (STN-HFS) in the treatment of Parkinson's disease and its interaction with levodopa (L-DOPA), focusing on the striatum. Striatal gene expression profile was assessed in rats with nigral dopamine neuron lesion, either treated or not, using agilent microarrays and qPCR verification. The treatments consisted in anti-akinetic STN-HFS (5 days), chronic L-DOPA treatment inducing dyskinesia (LIDs) or the combination of the two treatments that exacerbated LIDs. STN-HFS modulated 71 striatal genes. The main biological processes associated with the differentially expressed gene products include regulation of growth, of apoptosis and of synaptic transmission, and extracellular region is a major cellular component implicated. In particular, several of these genes have been shown to support survival or differentiation of striatal or of dopaminergic neurons. These results indicate that STN HFS may induce widespread anatomo-functional rearrangements in the striatum and create a molecular environment favorable for neuroprotection and neuroplasticity. STN-HFS and L-DOPA treatment share very few common gene regulation features indicating that the molecular substrates underlying their striatal action are mostly different; among the common effects is the down-regulation of Adrb1, which encodes the adrenergic beta-1-receptor, supporting a major role of this receptor in Parkinson's disease. In addition to genes already reported to be associated with LIDs (preprodynorphin, thyrotropin-releasing hormone, metabotropic glutamate receptor 4, cannabinoid receptor 1), the comparison between DOPA and DOPA/HFS identifies immunity-related genes as potential players in L-DOPA side effects.

Supplementary motor area stimulation for Parkinson disease

Objective:

To explore the efficacy and stimulation frequency dependence of repetitive transcranial magnetic stimulation (rTMS) over the supplementary motor area (SMA) in Parkinson disease (PD).

Methods:

In this randomized, double-blind, sham-controlled, multicenter study with a parallel design, a weekly intervention was performed 8 times. The effects were monitored up to 20 weeks. By central registration, participants were assigned to 1 of 3 arms of the study: low-frequency (1-Hz) rTMS, high-frequency (10-Hz) rTMS, and realistic sham stimulation. The primary end point was the score change of the Unified Parkinson's Disease Rating Scale (UPDRS) part III from the baseline. Several nonmotor symptom scales such as the Hamilton Rating Scale for Depression, apathy score, and nonmotor symptoms questionnaire were defined as secondary end points.

Results:

Of the 106 patients enrolled, 36 were allocated to 1-Hz rTMS, 34 to 10-Hz rTMS, and 36 to realistic sham stimulation. Results show 6.84-point improvement of the UPDRS part III in the 1-Hz group at the last visit of the 20th week. Sham stimulation and 10-Hz rTMS improved motor symptoms transiently, but their effects disappeared in the observation period. Changes in nonmotor symptoms were not clear in any group. No severe adverse event was reported.

Conclusions:

The 1-Hz rTMS over the SMA was effective for motor, but not nonmotor, symptoms in PD.

Level of evidence:

This study provides Class I evidence that 1-Hz rTMS over the SMA is effective for motor symptoms in PD.

Wireless neurochemical monitoring in humans

Electrochemical techniques have long been utilized to investigate chemical changes in the neuronal microenvironment. Preclinical models have demonstrated the successful monitoring of changes in various neurotransmitter systems in vivo with high temporal and spatial resolution. The expansion of electrochemical recording to humans is a critical yet challenging goal to elucidate various aspects of human neurophysiology and to create future therapies. We have designed a novel device named the WINCS (Wireless Instantaneous Neurotransmitter Concentration Sensing) system that combines rapid scan voltammetry with wireless telemetry for highly resolved electrochemical recording and analysis. WINCS utilizes fast-scan cyclic voltammetry and fixed potential amperometry for in vivo recording and has demonstrated high temporal and spatial resolution in detecting changes in extracellular levels of a wide range of analytes including dopamine, adenosine, glutamate, serotonin, and histamine. Neurochemical monitoring in humans represents a new approach to understanding the neurophysiology of the central nervous system, the neurobiology of numerous diseases, and the underlying mechanism of various neurosurgical therapies. This article addresses the current understanding of electrochemistry, its application in humans, and future directions.

80 Hz versus 130 Hz subthalamic nucleus deep brain stimulation: effects on involuntary movements

BACKGROUND

Subthalamic Nucleus Deep Brain Stimulation (STN-DBS) represents a valid therapeutic option for advanced Parkinson's disease (PD), leading to a significant amelioration of motor fluctuations and levodopa-induced involuntary movements (IM). This study address the issue of whether stimulation frequency may influence the control of IM in STN-DBS treated patients, comparing the effects of 80 Hz and 130 Hz STN-DBS frequencies in 10 parkinsonian patients with residual IM (dyskinesia in 6 cases and dystonia in 4 cases).

METHODS

Patients were evaluated by means of the Rush Dyskinesias Rating Scale (blinded-video analysis) and Unified Parkinson's Disease Rating Scale at 4 different time-points: baseline, shortly after the switch of stimulation frequency from 130 Hz to 80 Hz, after 1 month and 12 months of chronic 80 Hz stimulation.

RESULTS

IM improved in most subjects after the switch of stimulation frequency: dyskinesias improved in 6/6 subjects and dystonic features in 3/4 subjects after one month of 80 Hz stimulation. However, the 130 Hz STN stimulation was restored in 4 subjects during the following months, because of a gradual worsening of parkinsonian symptoms. A sustained efficacy on motor features and IM was observed with 80 Hz stimulation frequency in the remaining patients.

CONCLUSIONS

In this limited cohort of STN-DBS patients, we observed an improvement of residual IM after the switch of stimulation frequency from 130 Hz to 80 Hz. However, a moderate worsening of parkinsonian symptoms was observed in a portion of patients, requiring to return at 130 Hz STN-DBS.

Signal transmission through human muscle for implantable medical devices using galvanic intra-body communication technique

Signal transmission over human tissues has long been the center research topic for biomedical engineering in both academic and industrial arenas. This is particular important for implantable medical devices (IMD) to communicate with other sensor devices in achieving health care and monitoring functions. Traditional Radio Frequency (RF) transmission technique suffers from not only high attenuation but also potential interference & eavesdropping. This paper has examined the alternate galvanic type Intra-Body Communication Technique (IBC) in transmitting signal across the body tissue (mainly muscle) in both analytical electromagnetic model with simulation results. Comparisons of these results with traditional RF data in literatures show a high promising potential (saving over 10 dB or more in path loss) for IBC transmission. Concrete discussions and several further research directions are also given out at the end of this paper.

DBS in the basolateral amygdala improves symptoms of autism and related self-injurious behavior: a case report and hypothesis on the pathogenesis of the disorder

We treated a 13-year-old boy for life-threatening self-injurious behavior (SIB) and severe Kanner's autism with deep brain stimulation (DBS) in the amygdaloid complex as well as in the supra-amygdaloid projection system. Two DBS-electrodes were placed in both structures of each hemisphere. The stimulation contacts targeted the paralaminar, the basolateral (BL), the central amygdala as well as the supra-amygdaloid projection system. DBS was applied to each of these structures, but only stimulation of the BL part proved effective in improving SIB and core symptoms of the autism spectrum in the emotional, social, and even cognitive domains over a follow up of now 24 months. These results, which have been gained for the first time in a patient, support hypotheses, according to which the amygdala may be pivotal in the pathogeneses of autism and point to the special relevance of the BL part.

Functional neurosurgery in Parkinson's disease: a long journey from destruction over modulation towards restoration

Neurosurgical treatment of Parkinson's disease (PD) has re-gained considerable attention over the last two decades due to a better understanding of the pathophysiology of the basal ganglia, the long-term complications of medical treatment, and advances in neuroimaging and neurosurgical techniques. The introduction of deep brain stimulation (DBS) has created new perspectives for the surgical management of PD patients, due to the low morbidity, reversibility and improvement of both motor function and quality of life as compared to the lesioning techniques. We present an overview of basic principles, history, indications, and results of current neurosurgical techniques available in PD.

Deep brain stimulation induces rapidly reversible transcript changes in Parkinson's leucocytes

Subthalamic deep brain stimulation (DBS) reversibly modulates Parkinson's disease (PD) motor symptoms, providing an unusual opportunity to compare leucocyte transcripts in the same individuals before and after neurosurgery and 1 hr after stimulus cessation (ON- and OFF-stimulus). Here, we report DBS-induced reversibility and OFF-stimulus restoration in 12 of 16 molecular functions and 3 of 4 biological processes shown in exon microarrays to be differentially expressed between PD patients and controls, post-DBS from pre-DBS and OFF from ON states. Intriguingly, 6 of 18 inflammation and immune-related functions exhibited reversibility, and the extent of stimulus-induced changes correlated with the neurological DBS efficacy, suggesting mechanistic implications. A minimal list of 29 transcripts that changed in all three comparisons between states discriminated pre-surgery and OFF states from post-surgery and controls. Six of these transcripts were found to be able to distinguish between PD patients and both healthy controls and patients with other neurological diseases in a previously published whole blood 3’ array data study of early PD patients. Our findings support the future use of this approach for identifying targets for therapeutic intervention and assessing the efficacy of current and new treatments in this and other neurological diseases.

Robotic implantation of deep brain stimulation leads, assisted by intra-operative, flat-panel CT

BACKGROUND

There are two mandatory skills in deep brain stimulation (DBS) neurosurgery: accuracy and control.

METHOD

Frame-based robotic registration was performed. Prior to insertion into the skull, the guide tube's position was checked with flat-panel computed tomography (fpCT). After registration against the pre-operative plan, we measured and corrected the robotic arm's position so that the guide tube with the micro-electrode would follow the planned trajectory exactly. We then used fpCT again to check the DBS lead's final position.

CONCLUSION

The combination of intra-operative fpCT with robotised surgery provides an appropriate, user-friendly solution to the key technical challenges in DBS lead implantation.

Neuropsychological and quality of life assessment in patients with Parkinson's disease submitted to bilateral deep brain stimulation in the subthalamic nucleus

Deep brain stimulation (DBS) has been widely used to control motor symptoms and improve quality of life in patients with Parkinsons disease (PD). Recently, DBS in the subthalamic nucleus (STN) has become the preferred target for patients with mixed motor symptoms. Despite resultant motor and quality of life improvements, the procedure has been associated with cognitive decline, mainly in language skills, and also with psychiatric symptoms.

OBJECTIVE

To evaluate the influence of DBS in the STN on cognition, mood and quality of life.

METHODS

We studied 20 patients with PD submitted to DBS in the STN from May 2008 to June 2012 with an extensive battery of cognitive tests including memory, language, praxis, executive functions and attention assessments; the Parkinson's Disease Quality of Life Questionnaire (PDQ-39); and the Hospital Anxiety and Depression Scale (HAD), were applied both before and after the surgery. Data was analyzed using SPSS version 17.0 and results compared using the paired Student's t test.

RESULTS

A total of 20 patients with pre and post-operative assessments were included. A statistically significant improvement was found in total score and on subscales of mobility, activities of daily living and emotional well-being from the PDQ-39 (P=0.009, 0.025, 0.001 and 0.034, respectively). No significant difference was found on the cognitive battery or mood scale.

CONCLUSION

DBS in the SNT improved quality of life in PD with no negative impact on cognitive skills and mood.

Improved efficacy of temporally non-regular deep brain stimulation in Parkinson's disease

High frequency deep brain stimulation is an effective therapy for motor symptoms in Parkinson's disease. However, the relative clinical efficacy of regular versus non-regular temporal patterns of stimulation in Parkinson's disease remains unclear. To determine the temporal characteristics of non-regular temporal patterns of stimulation important for the treatment of Parkinson's disease, we compared the efficacy of temporally regular stimulation with four non-regular patterns of stimulation in subjects with Parkinson's disease using an alternating finger tapping task. The patterns of stimulation were also evaluated in a biophysical model of the parkinsonian basal ganglia that exhibited prominent oscillatory activity in the beta frequency range. The temporal patterns of stimulation differentially improved motor task performance. Three of the non-regular patterns of stimulation improved performance of the finger tapping task more than temporally regular stimulation. In the computational model all patterns of deep brain stimulation suppressed beta band oscillatory activity, and the degree of suppression was strongly correlated with the clinical efficacy across stimulation patterns. The three non-regular patterns of stimulation that improved motor performance over regular stimulation also suppressed beta band oscillatory activity in the computational model more effectively than regular stimulation. These data demonstrate that the temporal pattern of stimulation is an important consideration for the clinical efficacy of deep brain stimulation in Parkinson's disease. Furthermore, non-regular patterns of stimulation may ameliorate motor symptoms and suppress pathological rhythmic activity in the basal ganglia more effectively than regular stimulation. Therefore, non-regular patterns of deep brain stimulation may have useful clinical and experimental applications.

Painful cervical dystonia triggered by the extension wire of a deep brain stimulator

Deep brain stimulation (DBS) can be complicated by adverse events, which are generally classified as surgical-hardware or stimulation-related. Here we report the onset of a painful cervical dystonia probably triggered by the extension wire of a subthalamic nucleus (STN)-DBS device in a woman suffering from advanced Parkinson's disease (PD). Two months after implantation of the STN-DBS device, our patient developed a painful cervical dystonia, which was not responsive to neurostimulation or to medication. No sign of infections or fibrosis was detected. A patch test with the components of the device was performed, revealing no hypersensibility. The patient was referred back to surgery to reposition the pulse generator in the contralateral subclavian region. A deeper channeling of the wire extensions produced a complete remission of the painful dystonia.

An update on the management of juvenile and young-onset Parkinson’s disease

Early-onset Parkinson’s disease (PD) denotes onset of the disease below the age of 40 years. Patients tend to have a slower disease progression, an increased rate of dystonia, an increased rate of dyskinesias in response to L-3,4-dihydroxyphenylalanine and a lower rate of dementia compared with those in late-onset PD. Early-onset PD patients may experience more social and psychosocial conflict compared with late-onset patients and these factors would contribute to greater impairment of quality of life. Unemployment due to disability or early retirement may be causes for these conflicts. We have to take these factors into account whenever we institute drug therapy in early-onset PD. There is no randomized controlled study on early-onset PD; however, we may make a reasonable decision by considering the data on PD in general and clinical characteristics of early-onset patients. The management of motor and non-motor symptoms of early-onset PD patients is reviewed here.

Optogenetics: a novel optical manipulation tool for medical investigation

Optogenetics is a new and rapidly evolving gene and neuroengineering technology that allows optical control of specific populations of neurons without affecting other neurons in the brain at high temporal and spatial resolution. By heterologous expression of the light-sensitive membrane proteins, cell type-specific depolarization or hyperpolarization can be optically induced on a millisecond time scale. Optogenetics has the higher selectivity and specificity compared to traditional electrophysiological techniques and pharmaceutical methods. It has been a novel promising tool for medical research. Because of easy handling, high temporal and spatial precision, optogenetics has been applied to many aspects of nervous system research, such as tactual neural circuit, visual neural circuit, auditory neural circuit and olfactory neural circuit, as well as research of some neurological diseases. The review highlights the recent advances of optogenetics in medical study.

New targets for DBS

The specific effect of DBS at high frequency, discovered during a VIM thalamotomy, was extended to the older targets of ablative neurosurgery such as the pallidum, for tremor in Parkinson's disease (PD), dyskinesias, essential tremor, as well as the internal capsule to treat psychiatric disorders (OCD). A second wave of targets came from basic research, enabled by the low morbidity, reversibility, and adaptability of DBS. This was the case for the subthalamic nucleus (STN) which improves the triad of dopaminergic symptoms, and the pedunculopontine nucleus (PPN) for gait disorders in PD. The new concepts of the role of basal ganglia in psychiatric disorders indicate the subgenual cortex CG 25 for severe resistant depression, the accumbens nucleus for depression, anorexia nervosa, and addiction, and the thalamus intralaminar nuclei for minimally conscious states. Serendipity and a scientific approach have provided several instances where targets have produced unexpected effects (such as STN in OCD), as well as limbic effects observed during attempts at VMH stimulation for obesity: this might offer a novel way to treat mild cognitive impairment, or memory deficits reported in Alzheimer's disease. While these might provide solutions for as yet unsolved problems, attention must be paid to ethical considerations.