Electrical stimulation in anterior limbs of internal capsules in patients with obsessive-compulsive disorder

Electrical stimulation of the bed nucleus of the stria terminalis reduces anxiety in a rat model

We recently showed that deep brain stimulation (DBS) in the bed nucleus of the stria terminalis (BST) reduces obsessions, compulsions and associated anxiety in patients suffering from severe, treatment-refractory obsessive-compulsive disorder. Here, we investigated the anxiolytic effects of electrical BST stimulation in a rat model of conditioned anxiety, unrelated to obsessions or compulsions. Two sets of stimulation parameters were evaluated. Using fixed settings at 100 Hz, 40 μs and 300 μA (Set A), we observed elevated freezing and startle levels, whereas stimulation at 130 Hz, 220 μs and individually tailored amplitudes (Set B) appeared to reduce freezing. In a follow-up experiment, we evaluated the anxiolytic potential of Set B more extensively, by adding a lesion group and an additional day of stimulation. We found that electrical stimulation significantly reduced freezing, but not to the same extent as lesions. Neither lesions nor stimulation of the BST affected motor behavior or unconditioned anxiety in an open-field test. In summary, electrical stimulation of the BST was successful in reducing contextual anxiety in a rat model, without eliciting unwanted motor effects. Our findings underline the therapeutic potential of DBS in the BST for disorders that are hallmarked by pathological anxiety. Further research will be necessary to assess the translatability of these findings to the clinic.

Six-Nine Year Follow-Up of Deep Brain Stimulation for Obsessive-Compulsive Disorder

Objective

Deep brain stimulation (DBS) of the ventral capsule/ventral striatum (VC/VS) region has shown promise as a neurosurgical intervention for adults with severe treatment-refractory obsessive-compulsive disorder (OCD). Pilot studies have revealed improvement in obsessive-compulsive symptoms and secondary outcomes following DBS. We sought to establish the long-term safety and effectiveness of DBS of the VC/VS for adults with OCD.

Materials and Methods

A long term follow-up study (73–112 months) was conducted on the six patients who were enrolled in the original National Institute of Mental Health pilot study of DBS for OCD. Qualitative and quantitative data were collected.

Results

Reduction in OCD symptoms mirrored the one-year follow-up data. The same four participants who were treatment responders after one year of treatment showed a consistent OCD response (greater than 35% reduction in Yale Brown Obsessive Compulsive Scale (YBOCS)). Another subject, classified as a non-responder, achieved a 26% reduction in YBOCS score at long term follow-up. The only patient who did not achieve a 25% or greater reduction in YBOCS was no longer receiving active DBS treatment. Secondary outcomes generally matched the one-year follow-up with the exception of depressive symptoms, which significantly increased over the follow-up period. Qualitative feedback indicated that DBS was well tolerated by the subjects.

Discussion

These data indicate that DBS was safe and conferred a long-term benefit in reduction of obsessive-compulsive symptoms. DBS of the VC/VS region did not reveal a sustained response for comorbid depressive symptoms in patients with a primary diagnosis of OCD.

Deep brain stimulation of the subthalamic nucleus in obsessive-compulsive disorder: Neuroanatomical and pathophysiological considerations

Obsessive-compulsive disorder (OCD) is among the most disabling chronic psychiatric disorders and has a significant negative impact on multiple domains of quality of life. For patients suffering from severe refractory OCD, deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been applied. Reviewing the literature of the last years we believe that through its central position within the cortico-basal ganglia-thalamocortical circuits, the STN has a coordinating role in decision-making and action-selection mechanisms. Dysfunctional information-processing at the level of the STN is responsible for some of the core symptoms of OCD. Research confirms an electrophysiological dysfunction in the associative and limbic (non-motor) parts of the STN. Compared to Parkinson׳s disease patients, STN neurons in OCD exhibit a lower firing rate, less frequent but longer bursts, increased burst activity in the anterior ventromedial area, an asymmetrical left-sided burst distribution, and a predominant oscillatory activity in the δ-band. Moreover, there is direct evidence for the involvement of the STN in both checking behavior and OCD symptoms, which are both related to changes in electrophysiological activity in the non-motor STN. Through a combination of mechanisms, DBS of the STN seems to interrupt the disturbed information-processing, leading to a normalization of connectivity within the cortico-basal ganglia-thalamocortical circuits and consequently to a reduction in symptoms. In conclusion, based on the STN׳s strategic position within cortico-basal ganglia-thalamocortical circuits and its involvement in action-selection mechanisms that are responsible for some of the core symptoms of OCD, the STN is a mechanism-based target for DBS in OCD.

Acute deep brain stimulation changes in regional cerebral blood flow in obsessive-compulsive disorder

OBJECTIVE Deep brain stimulation (DBS) is a reversible, nonlesion-based treatment for patients with intractable obsessive-compulsive disorder (OCD). The first studies on DBS for OCD stimulating the ventral capsule/ventral striatum (VC/VS) yielded encouraging results for this neuroanatomical site's therapeutic efficacy. This investigation was conducted to better understand which regions of the cortico-striatal-thalamic-cortical network were acutely affected by VC/VS DBS for OCD. Furthermore, the objective was to identify which brain regions demonstrated changes in perfusion, as stimulation was applied across a dorsoventral lead axis that corresponded to different anatomical locations in the VC/VS. METHODS Six patients receiving VC/VS DBS for OCD underwent oxygen-15 positron emission tomography (¹⁵O-PET) scanning. Monopolar DBS was delivered at each of the 4 different electrodes on the stimulating lead in the VC/VS. The data were analyzed using SPM5. Paired t-tests were run in SPSS to identify significant changes in regional cerebral blood flow (rCBF) between stimulation conditions. Pearson's r correlations were run between these significant changes in rCBF and changes in OCD and depressive symptom severity. RESULTS Perfusion in the dorsal anterior cingulate cortex (dACC) significantly increased when monopolar DBS was turned on at the most ventral DBS contact, and this increase in dACC activity was correlated with reductions in depressive symptom severity (r(5) = -0.994, p = 0.001). Perfusion in the thalamus, striatum, and globus pallidus significantly increased when DBS was turned on at the most dorsal contact. CONCLUSIONS DBS of the VC/VS appears to modulate activity in the regions implicated in the pathophysiology of OCD. Different regions in the cortico-striatal-thalamic-cortical circuit showed increased perfusion based on whether the stimulation was more ventral or dorsal along the lead axis in the VC/VS. Evidence was found that DBS at the most ventral site was associated with clinical changes in depressive symptom severity, but not OCD symptom severity.

Field Potential Oscillations in the Bed Nucleus of the Stria Terminalis Correlate with Compulsion in a Rat Model of Obsessive-Compulsive Disorder

The bed nucleus of the stria terminalis (BNST) is implicated in anxiety and reward processing, both of which are associated with obsessive-compulsive disorder (OCD). Specific neuronal groups in the BNST related to anxiety and reward have been identified, but quantitative data about the information carried by local field potential (LFP) signals in this area during obsession/compulsion are lacking. Here we investigate the BNST LFP in the schedule-induced polydipsia, an animal model of OCD. We implanted electrodes bilaterally in the BNST and random control brain regions in 32 male Wistar rats, and recorded corresponding LFP during compulsive and noncompulsive behavior. We first applied high-frequency (100 Hz) electrical stimulation through the implanted electrodes and analyzed its effects on compulsive behavior. We then performed time-frequency analysis of LFPs and statistically compared the normalized power of δ (1-4 Hz), θ (4-8 Hz), α (8-12 Hz), β (12-30 Hz), and lower γ (30-45 Hz) bands between different groups. Our data showed that the normalized δ, β, and γ powers in the right BNST were specifically correlated with compulsive behaviors. δ and γ oscillations increased and decreased during the initiation phase of compulsion, respectively, whereas β increased after compulsion stopped. Moreover, the effect of BNST electrical stimulation, in terms of suppression of compulsion, was significantly correlated with the percentage change of these bands during compulsion. Our research reveals potential biomarkers and underlying neurophysiological mechanisms of compulsion and warrants further assessment of the use of LFP for closed-loop neuromodulation in OCD.

SIGNIFICANCE STATEMENT

Although specific neuronal groups in the bed nucleus of the stria terminalis (BNST) related to anxiety and reward circuitries have been identified, psychopathological information carried by local field potentials in the BNST has not yet been described. We discovered that normalized powers of the right BNST δ, β, and γ oscillations were highly correlated with compulsion. Specifically, δ and γ oscillations increased and decreased during the initiation phase of compulsion, respectively, whereas β increased after compulsion stopped. Such correlations were not found in other parts of the brain during compulsion, or in the BNST during noncompulsive behavior. Current findings reveal real-time neurophysiological biomarkers of compulsion and warrant further assessment of the use of local field potentials for closed-loop neuromodulation for OCD.

Functional Magnetic Resonance Imaging of Electrical and Optogenetic Deep Brain Stimulation at the Rat Nucleus Accumbens

Deep brain stimulation of the nucleus accumbens (NAc-DBS) is an emerging therapy for diverse, refractory neuropsychiatric diseases. Although DBS therapy is broadly hypothesized to work through large-scale neural modulation, little is known regarding the neural circuits and networks affected by NAc-DBS. Using a healthy, sedated rat model of NAc-DBS, we employed both evoked- and functional connectivity (fc) MRI to examine the functional circuit and network changes achieved by electrical NAc stimulation. Optogenetic-fMRI experiments were also undertaken to evaluate the circuit modulation profile achieved by selective stimulation of NAc neurons. NAc-DBS directly modulated neural activity within prefrontal cortex and a large number of subcortical limbic areas (e.g., amygdala, lateral hypothalamus), and influenced functional connectivity among sensorimotor, executive, and limbic networks. The pattern and extent of circuit modulation measured by evoked-fMRI was relatively insensitive to DBS frequency. Optogenetic stimulation of NAc cell bodies induced a positive fMRI signal in the NAc, but no other detectable downstream responses, indicating that therapeutic NAc-DBS might exert its effect through antidromic stimulation. Our study provides a comprehensive mapping of circuit and network-level neuromodulation by NAc-DBS, which should facilitate our developing understanding of its therapeutic mechanisms of action.

Electrical stimulation in the bed nucleus of the stria terminalis alleviates severe obsessive-compulsive disorder

In 1998, we proposed deep brain stimulation as a last-resort treatment option for patients suffering from severe, treatment-resistant obsessive-compulsive disorder (OCD). Here, 24 OCD patients were included in a long-term follow-up study to evaluate the effects of electrical stimulation in the anterior limbs of the internal capsule (ALIC) and bed nucleus of the stria terminalis (BST). We find that electrical stimulation in the ALIC/BST area is safe and significantly decreases obsessions, compulsions, and associated anxiety and depressive symptoms, and improves global functioning in a blinded crossover trial (n=17), after 4 years (n=18), and at last follow-up (up to 171 months, n=24). Moreover, our data indicate that BST may be a better stimulation target compared with ALIC to alleviate OCD symptoms. We conclude that electrical stimulation in BST is a promising therapeutic option for otherwise treatment-resistant OCD patients.

Deep Brain Stimulation of Medial Dorsal and Ventral Anterior Nucleus of the Thalamus in OCD: A Retrospective Case Series

BACKGROUND

The current notion that cortico-striato-thalamo-cortical circuits are involved in the pathophysiology of obsessive-compulsive disorder (OCD) has instigated the search for the most suitable target for deep brain stimulation (DBS). However, despite extensive research, uncertainty about the ideal target remains with many structures being underexplored. The aim of this report is to address a new target for DBS, the medial dorsal (MD) and the ventral anterior (VA) nucleus of the thalamus, which has thus far received little attention in the treatment of OCD.

METHODS

In this retrospective trial, four patients (three female, one male) aged 31-48 years, suffering from therapy-refractory OCD underwent high-frequency DBS of the MD and VA. In two patients (de novo group) the thalamus was chosen as a primary target for DBS, whereas in two patients (rescue DBS group) lead implantation was performed in a rescue DBS attempt following unsuccessful primary stimulation.

RESULTS

Continuous thalamic stimulation yielded no significant improvement in OCD symptom severity. Over the course of thalamic DBS symptoms improved in only one patient who showed "partial response" on the Yale-Brown Obsessive Compulsive (Y-BOCS) Scale. Beck Depression Inventory scores dropped by around 46% in the de novo group; anxiety symptoms improved by up to 34%. In the de novo DBS group no effect of DBS on anxiety and mood was observable.

CONCLUSION

MD/VA-DBS yielded no adequate alleviation of therapy-refractory OCD, the overall strategy in targeting MD/VA as described in this paper can thus not be recommended in DBS for OCD. The magnocellular portion of MD (MDMC), however, might prove a promising target in the treatment of mood related and anxiety disorders.

The pros and cons of intraoperative CT scan in evaluation of deep brain stimulation lead implantation: A retrospective study

BACKGROUND

Deep brain stimulation (DBS) is an established therapy for movement disorders, such as Parkinson's disease (PD), dystonia, and tremor. The efficacy of DBS depends on the correct lead positioning. The commonly adopted postoperative radiological evaluation is performed with computed tomography (CT) scan and/or magnetic resonance imaging (MRI).

METHODS

We conducted a retrospective study on 202 patients who underwent DBS from January 2009 to October 2013. DBS indications were PD, progressive supranuclear palsy, tremor, dystonia, Tourette syndrome, obsessive compulsive disorder, depression, and Huntington's disease. Preoperatively, all patients underwent brain MRI and brain CT scan with the stereotactic frame positioned. The lead location was confirmed intraoperatively with CT. The CT images were subsequently transferred to the Stealth Station Medtronic and merged with the preoperative planning. On the first or second day after, implantation we performed a brain MRI to confirm the correct position of the lead.

RESULTS

In 14 patients, leads were in suboptimal position after intraoperative CT scan positioning. The cases with alteration in the Z-axis were corrected immediately under fluoroscopic guidance. In all the 14 patients, an immediate repositioning was done.

CONCLUSIONS

Based on our data, intraoperative CT scan is fast, safe, and a useful tool in the evaluation of the position of the implanted lead. It also reduces the patient's discomfort derived from the transfer of the patient from the operating room to the radiological department. However, intraoperative CT should not be considered as a substitute for postoperative MRI.

Computational Modeling and Neuroimaging Techniques for Targeting during Deep Brain Stimulation

Accurate surgical localization of the varied targets for deep brain stimulation (DBS) is a process undergoing constant evolution, with increasingly sophisticated techniques to allow for highly precise targeting. However, despite the fastidious placement of electrodes into specific structures within the brain, there is increasing evidence to suggest that the clinical effects of DBS are likely due to the activation of widespread neuronal networks directly and indirectly influenced by the stimulation of a given target. Selective activation of these complex and inter-connected pathways may further improve the outcomes of currently treated diseases by targeting specific fiber tracts responsible for a particular symptom in a patient-specific manner. Moreover, the delivery of such focused stimulation may aid in the discovery of new targets for electrical stimulation to treat additional neurological, psychiatric, and even cognitive disorders. As such, advancements in surgical targeting, computational modeling, engineering designs, and neuroimaging techniques play a critical role in this process. This article reviews the progress of these applications, discussing the importance of target localization for DBS, and the role of computational modeling and novel neuroimaging in improving our understanding of the pathophysiology of diseases, and thus paving the way for improved selective target localization using DBS.

The Co-evolution of Neuroimaging and Psychiatric Neurosurgery

The role of neuroimaging in psychiatric neurosurgery has evolved significantly throughout the field's history. Psychiatric neurosurgery initially developed without the benefit of information provided by modern imaging modalities, and thus lesion targets were selected based on contemporary theories of frontal lobe dysfunction in psychiatric disease. However, by the end of the 20th century, the availability of structural and functional magnetic resonance imaging (fMRI) allowed for the development of mechanistic theories attempting to explain the anatamofunctional basis of these disorders, as well as the efficacy of stereotactic neuromodulatory treatments. Neuroimaging now plays a central and ever-expanding role in the neurosurgical management of psychiatric disorders, by influencing the determination of surgical candidates, allowing individualized surgical targeting and planning, and identifying network-level changes in the brain following surgery. In this review, we aim to describe the coevolution of psychiatric neurosurgery and neuroimaging, including ways in which neuroimaging has proved useful in elucidating the therapeutic mechanisms of neuromodulatory procedures. We focus on ablative over stimulation-based procedures given their historical precedence and the greater opportunity they afford for post-operative re-imaging, but also discuss important contributions from the deep brain stimulation (DBS) literature. We conclude with a discussion of how neuroimaging will transition the field of psychiatric neurosurgery into the era of precision medicine.

New treatment models for compulsive disorders

Obsessive compulsive disorder (OCD) as well as related disorders such as body dysmorphic disorder, tic disorder, and trichotillomania are all common and often debilitating. Although treatments are available, more effective approaches to these problems are needed. Thus this review article presents what is currently known about OCD and related disorders and suggests that understanding OCD more broadly as a compulsive disorder may allow for more effective treatment options. Toward that goal, the review presents new models of psychopharmacology and psychotherapy, as well as new brain stimulation strategies. Treatment advances, grounded in the neuroscience, have promise in advancing treatment response for OCD as well as other disorders of compulsivity.

Removing and reimplanting deep brain stimulation therapy devices in resistant OCD (when the patient does not respond): case report

BACKGROUND

Deep brain stimulation (DBS) is emerging as a promising tool in the treatment of refractory obsessive-compulsive disorder (OCD) but the search for the best target still continues. This issue is especially relevant when particularly resistant profiles are observed in some patients, which have been ascribed to individual responses to DBS according to differential patterns of connectivity. As patients have been implanted, new dilemmas have emerged, such as what to do when the patient does not respond to surgery.

CASE PRESENTATION

Here we describe a 22-year-old male with extremely severe OCD who did not respond to treatment with DBS in the nucleus accumbens, but who did respond after explanting and reimplanting leads targeting the ventral capsule-ventral striatum region. Information regarding the position of the electrodes for both surgeries is provided and possible brain structures affected during stimulation are reviewed. To our knowledge this case is the first in the literature reporting the removal and reimplantation of DBS leads for therapeutical benefits in a patient affected by a mental disorder.

CONCLUSION

The capability for explantation and reimplantation of leads should be considered as part of the DBS therapy reversibility profile in resistant mental disorders, as it allows application in cases of non-response to the first surgery.

An integrated multi-electrode-optrode array for in vitro optogenetics

Modulation of a group of cells or tissue needs to be very precise in order to exercise effective control over the cell population under investigation. Optogenetic tools have already demonstrated to be of great value in the study of neuronal circuits and in neuromodulation. Ideally, they should permit very accurate resolution, preferably down to the single cell level. Further, to address a spatially distributed sample, independently addressable multiple optical outputs should be present. In current techniques, at least one of these requirements is not fulfilled. In addition to this, it is interesting to directly monitor feedback of the modulation by electrical registration of the activity of the stimulated cells. Here, we present the fabrication and characterization of a fully integrated silicon-based multi-electrode-optrode array (MEOA) for in vitro optogenetics. We demonstrate that this device allows for artifact-free electrical recording. Moreover, the MEOA was used to reliably elicit spiking activity from ChR2-transduced neurons. Thanks to the single cell resolution stimulation capability, we could determine spatial and temporal activation patterns and spike latencies of the neuronal network. This integrated approach to multi-site combined optical stimulation and electrical recording significantly advances today's tool set for neuroscientists in their search to unravel neuronal network dynamics.

Tractography Activation Patterns in Dorsolateral Prefrontal Cortex Suggest Better Clinical Responses in OCD DBS

Background: Medication resistant obsessive-compulsive disorder (OCD) patients can be successfully treated with Deep Brain Stimulation (DBS) which targets the anterior limb of the internal capsule (ALIC) and the nucleus accumbens (NA). Growing evidence suggests that in patients who respond to DBS, axonal fiber bundles surrounding the electrode are activated, but it is currently unknown which discrete pathways are critical for optimal benefit. Our aim was to identify axonal pathways mediating clinical effects of ALIC-NA DBS.

Methods: We created computational models of ALIC-NA DBS to simulate the activation of fiber tracts and to identify connected cerebral regions. The pattern of activated axons and their cortical targets was investigated in six OCD patients who underwent ALIC-NA DBS.

Results: Modulation of the right anterior middle frontal gyrus (dorsolateral prefrontal cortex) was associated with an excellent response. In contrast, non-responders showed high activation in the orbital part of the right inferior frontal gyrus (lateral orbitofrontal cortex/anterior ventrolateral prefrontal cortex). Factor analysis followed by step-wise linear regression indicated that YBOCS improvement was inversely associated with factors that were predominantly determined by gray matter activation results.

Discussion: Our findings support the hypothesis that optimal therapeutic results are associated with the activation of distinct fiber pathways. This suggests that in DBS for OCD, focused stimulation of specific fiber pathways, which would allow for stimulation with lower amplitudes, may be superior to activation of a wide array of pathways, typically associated with higher stimulation amplitudes.

A decade of emerging indications: deep brain stimulation in the United States

OBJECTIVE Deep brain stimulation (DBS) is an emerging treatment option for an expanding set of neurological and psychiatric diseases. Despite growing enthusiasm, the patterns and implications of this rapid adoption are largely unknown. National trends in DBS surgery performed for all indications between 2002 and 2011 are reported. METHODS Using a national database of hospital discharges, admissions for DBS for 14 indications were identified and categorized as either FDA approved, humanitarian device exempt (HDE), or emerging. Trends over time were examined, differences were analyzed by univariate analyses, and outcomes were analyzed by hierarchical regression analyses. RESULTS Between 2002 and 2011, there were an estimated 30,490 discharges following DBS for approved indications, 1647 for HDE indications, and 2014 for emerging indications. The volume for HDE and emerging indications grew at 36.1% annually in comparison with 7.0% for approved indications. DBS for emerging indications occurred at hospitals with more neurosurgeons and neurologists locally, but not necessarily at those with the highest DBS caseloads. Patients treated for HDE and emerging indications were younger with lower comorbidity scores. HDE and emerging indications were associated with greater rates of reported complications, longer lengths of stay, and greater total costs. CONCLUSIONS DBS for HDE and emerging indications underwent rapid growth in the last decade, and it is not exclusively the most experienced DBS practitioners leading the charge to treat the newest indications. Surgeons may be selecting younger and healthier patients for their early experiences. Differences in reported complication rates warrant further attention and additional costs should be anticipated as surgeons gain experience with new patient populations and targets.

Implantable neurotechnologies: bidirectional neural interfaces--applications and VLSI circuit implementations

A bidirectional neural interface is a device that transfers information into and out of the nervous system. This class of devices has potential to improve treatment and therapy in several patient populations. Progress in very large-scale integration has advanced the design of complex integrated circuits. System-on-chip devices are capable of recording neural electrical activity and altering natural activity with electrical stimulation. Often, these devices include wireless powering and telemetry functions. This review presents the state of the art of bidirectional circuits as applied to neuroprosthetic, neurorepair, and neurotherapeutic systems.

A Randomized Sham-Controlled Trial of Deep Brain Stimulation of the Ventral Capsule/Ventral Striatum for Chronic Treatment-Resistant Depression

BACKGROUND

Multiple open-label trials of deep brain stimulation (DBS) for treatment-resistant depression (TRD), including those targeting the ventral capsule/ventral striatum target, have shown encouraging response rates. However, no randomized controlled trials of DBS for TRD have been published.

METHODS

Thirty patients with TRD participated in a sham-controlled trial of DBS at the ventral capsule/ventral striatum target for TRD. Patients were randomized to active versus sham DBS treatment in a blinded fashion for 16 weeks, followed by an open-label continuation phase. The primary outcome measure was response, defined as a 50% or greater improvement on the Montgomery-Åsberg Depression Rating Scale from baseline.

RESULTS

There was no significant difference in response rates between the active (3 of 15 subjects; 20%) and control (2 of 14 subjects; 14.3%) treatment arms and no significant difference between change in Montgomery-Åsberg Depression Rating Scale scores as a continuous measure upon completion of the 16-week controlled phase of the trial. The response rates at 12, 18, and 24 months during the open-label continuation phase were 20%, 26.7%, and 23.3%, respectively.

CONCLUSION

The results of this first randomized controlled study of DBS for the treatment of TRD did not demonstrate a significant difference in response rates between the active and control groups at the end of the 16-week controlled phase. However, a range of 20% to 26.7% of patients did achieve response at any time during the open-label continuation phase. Future studies, perhaps utilizing alternative study designs and stimulation parameters, are needed.

Cellular mechanisms of deep brain stimulation: activity-dependent focal circuit reprogramming?

Deep brain stimulation (DBS) is a well-established treatment modality for movement disorders. As more behavioral disorders are becoming understood as specific disruptions in neural circuitry, the therapeutic realm of DBS is broadening to encompass a wider range of domains, including disorders of compulsion, affect, and memory, but current understanding of the cellular mechanisms of DBS remains limited. We review progress made during the last decade focusing in particular on how recent methods for targeted circuit manipulations, imaging and reconstruction are fostering preclinical and translational advances that improve our neurobiological understanding of DBS's action in psychiatric disorders.

Microfabricated polymer-based neural interface for electrical stimulation/recording, drug delivery, and chemical sensing--development

We present here a microfabricated, multi-functional neural interface with the ability to selectively apply electrical and chemical stimuli, while simultaneously monitoring both electrical and chemical activity in the brain. Such a comprehensive approach is required to understand and treat neuropsychiatric disorders, such as major depressive disorder (MDD), and to understand the mechanisms underlying treatments, such as pharmaceutical therapies and deep brain stimulation (DBS). The polymer-based, multi-functional neural interface is capable of electrical stimulation and recording, targeted drug delivery, and electrochemical sensing. A variety of different electrode and fluidic channel arrangements are possible with this fabrication process. Preliminary testing has shown the suitability of these neural interfaces for in vivo electrical stimulation and recording, as well as in vitro chemical sensing. Testing of the in vitro drug delivery and combined in vivo functionalities this neural interface are currently underway.

Deep Brain Stimulation for Obsessive-Compulsive Disorder: A Meta-Analysis of Treatment Outcome and Predictors of Response

Background

Deep brain stimulation (DBS) has been proposed as an alternative to ablative neurosurgery for severe treatment-resistant Obsessive-Compulsive Disorder (OCD), although with partially discrepant results probably related to differences in anatomical targetting and stimulation conditions. We sought to determine the efficacy and tolerability of DBS in OCD and the existence of clinical predictors of response using meta-analysis.

Methods

We searched the literature on DBS for OCD from 1999 through January 2014 using PubMed/MEDLINE and PsycINFO. We performed fixed and random-effect meta-analysis with score changes (pre-post DBS) on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) as the primary-outcome measure, and the number of responders to treatment, quality of life and acceptability as secondary measures.

Findings

Thirty-one studies involving 116 subjects were identified. Eighty-three subjects were implanted in striatal areas—anterior limb of the internal capsule, ventral capsule and ventral striatum, nucleus accumbens and ventral caudate—27 in the subthalamic nucleus and six in the inferior thalamic peduncle. Global percentage of Y-BOCS reduction was estimated at 45.1% and global percentage of responders at 60.0%. Better response was associated with older age at OCD onset and presence of sexual/religious obsessions and compulsions. No significant differences were detected in efficacy between targets. Five patients dropped out, but adverse effects were generally reported as mild, transient and reversible.

Conclusions

Our analysis confirms that DBS constitutes a valid alternative to lesional surgery for severe, therapy-refractory OCD patients. Well-controlled, randomized studies with larger samples are needed to establish the optimal targeting and stimulation conditions and to extend the analysis of clinical predictors of outcome.

Deep brain stimulation for obsessive-compulsive disorder: systematic review and evidence-based guideline sponsored by the American Society for Stereotactic and Functional Neurosurgery and the Congress of Neurological Surgeons (CNS) and endorsed by the CNS and American Association of Neurological Surgeons

BACKGROUND

It is estimated that 40% to 60% of patients with obsessive-compulsive disorder (OCD) continue to experience symptoms despite adequate medical management. For this population of treatment-refractory patients, promising results have been reported with the use of deep brain stimulation (DBS).

OBJECTIVE

To conduct a systematic review of the literature and develop evidence-based guidelines on DBS for OCD.

METHODS

A systematic literature search was undertaken using the PubMed database for articles published between 1966 and October 2012 combining the following words: "deep brain stimulation and obsessive-compulsive disorder" or "electrical stimulation and obsessive-compulsive disorder." Of 353 articles, 7 were retrieved for full-text review and analysis. The quality of the articles was assigned to each study and the strength of recommendation graded according to the guidelines development methodology of the American Association of Neurological Surgeons/Congress of Neurological Surgeons Joint Guidelines Committee.

RESULTS

Of the 7 studies, 1 class I and 2 class II double-blind, randomized, controlled trials reported that bilateral DBS is more effective in improving OCD symptoms than sham treatment.

CONCLUSION

Based on the data published in the literature, the following recommendations can be made: (1) There is Level I evidence, based on a single class I study, for the use of bilateral subthalamic nucleus DBS for the treatment of medically refractory OCD. (2) There is Level II evidence, based on a single class II study, for the use of bilateral nucleus accumbens DBS for the treatment of medically refractory OCD. (3) There is insufficient evidence to make a recommendation for the use of unilateral DBS for the treatment of medically refractory OCD.

Abnormal neuronal activity in Tourette syndrome and its modulation using deep brain stimulation

Tourette syndrome (TS) is a common childhood-onset disorder characterized by motor and vocal tics that are typically accompanied by a multitude of comorbid symptoms. Pharmacological treatment options are limited, which has led to the exploration of deep brain stimulation (DBS) as a possible treatment for severe cases. Multiple lines of evidence have linked TS with abnormalities in the motor and limbic cortico-basal ganglia (CBG) pathways. Neurophysiological data have only recently started to slowly accumulate from multiple sources: noninvasive imaging and electrophysiological techniques, invasive electrophysiological recordings in TS patients undergoing DBS implantation surgery, and animal models of the disorder. These converging sources point to system-level physiological changes throughout the CBG pathway, including both general altered baseline neuronal activity patterns and specific tic-related activity. DBS has been applied to different regions along the motor and limbic pathways, primarily to the globus pallidus internus, thalamic nuclei, and nucleus accumbens. In line with the findings that also draw on the more abundant application of DBS to Parkinson's disease, this stimulation is assumed to result in changes in the neuronal firing patterns and the passage of information through the stimulated nuclei. We present an overview of recent experimental findings on abnormal neuronal activity associated with TS and the changes in this activity following DBS. These findings are then discussed in the context of current models of CBG function in the normal state, during TS, and finally in the wider context of DBS in CBG-related disorders.

Deep brain stimulation for movement disorders: update on recent discoveries and outlook on future developments

Modern deep brain stimulation (DBS) has become a routine therapy for patients with movement disorders such as Parkinson's disease, generalized or segmental dystonia and for multiple forms of tremor. Growing numbers of publications also report beneficial effects in other movement disorders such as Tourette's syndrome, various forms of chorea and DBS is even being studied for Parkinson's-related dementia. While exerting remarkable effects on many motor symptoms, DBS does not restore normal neurophysiology and therefore may also have undesirable side effects including speech and gait deterioration. Furthermore, its efficacy might be compromised in the long term, due to progression of the underlying disease. Various programming strategies have been studied to try and address these issues, e.g., the use of low-frequency rather than high-frequency stimulation or the targeting of alternative brain structures such as the pedunculopontine nucleus. In addition, further technical developments will soon provide clinicians with an expanded choice of hardware such as segmented electrodes allowing for a steering of the current to optimize beneficial effects and reduce side effects as well as the possibility of adaptive stimulation systems based on closed-loop concepts with or without accompanying advances in programming and imaging software. In the present article, we will provide an update on the most recent achievements and discoveries relevant to the application of DBS in the treatment of movement disorder patients and give an outlook on future clinical and technical developments.

Deep brain stimulation for the obsessive-compulsive and Tourette-like symptoms of Kleefstra syndrome

Deep brain stimulation (DBS) has been reported to have beneficial effects in severe, treatment-refractory cases of obsessive-compulsive disorder (OCD) and Tourette syndrome (TS). In this report, the authors present the first case in which DBS was used to treat the neuropsychiatric symptoms of Kleefstra syndrome, a rare genetic disorder characterized by childhood hypotonia, intellectual disability, distinctive facial features, and myriad psychiatric and behavioral disturbances. A 24-year-old female patient with childhood hypotonia, developmental delay, and diagnoses of autism spectrum disorder, OCD, and TS refractory to medical management underwent the placement of bilateral ventral capsule/ventral striatum (VC/VS) DBS leads, with clinical improvement. Medical providers and family observed gradual and progressive improvement in the patient's compulsive behaviors, coprolalia, speech, and social interaction. Symptoms recurred when both DBS electrodes failed because of lead fracture and dislodgement, although the clinical benefits were restored by lead replacement. The symptomatic and functional improvements observed in this case of VC/VS DBS for Kleefstra syndrome suggest a novel indication for DBS worthy of further investigation.

Deep brain stimulation for psychiatric disorders: where we are now

Fossil records showing trephination in the Stone Age provide evidence that humans have sought to influence the mind through physical means since before the historical record. Attempts to treat psychiatric disease via neurosurgical means in the 20th century provided some intriguing initial results. However, the indiscriminate application of these treatments, lack of rigorous evaluation of the results, and the side effects of ablative, irreversible procedures resulted in a backlash against brain surgery for psychiatric disorders that continues to this day. With the advent of psychotropic medications, interest in invasive procedures for organic brain disease waned.

Diagnosis and classification of psychiatric diseases has improved, due to a better understanding of psychiatric patho-physiology and the development of disease and treatment biomarkers. Meanwhile, a significant percentage of patients remain refractory to multiple modes of treatment, and psychiatric disease remains the number one cause of disability in the world. These data, along with the safe and efficacious application of deep brain stimulation (DBS) for movement disorders, in principle a reversible process, is rekindling interest in the surgical treatment of psychiatric disorders with stimulation of deep brain sites involved in emotional and behavioral circuitry.

This review presents a brief history of psychosurgery and summarizes the development of DBS for psychiatric disease, reviewing the available evidence for the current application of DBS for disorders of the mind.

Deep brain stimulation versus anterior capsulotomy for obsessive-compulsive disorder: a review of the literature

Obsessive-compulsive disorder (OCD) is a chronic and debilitating psychiatric condition. Traditionally, anterior capsulotomy (AC) was an established procedure for treatment of patients with refractory OCD. Over recent decades, deep brain stimulation (DBS) has gained popularity. In this paper the authors review the published literature and compare the outcome of AC and DBS targeting of the area of the ventral capsule/ventral striatum (VC/VS) and nucleus accumbens (NAcc).

Patients in published cases were grouped according to whether they received AC or DBS and according to their preoperative scores on the Yale-Brown Obsessive-Compulsive Scale (YBOCS), and then separated according to outcome measures: remission (YBOCS score < 8); response (≥ 35% improvement in YBOCS score); nonresponse (< 35% improvement in YBOCS score); and unfavorable (i.e., worsening of the baseline YBOCS score).

Twenty studies were identified reporting on 170 patients; 62 patients underwent DBS of the VC/VS or the NAcc (mean age 38 years, follow-up 19 months, baseline YBOCS score of 33), and 108 patients underwent AC (mean age 36 years, follow-up 61 months, baseline YBOCS score of 30). In patients treated with DBS there was a 40% decrease in YBOCS score, compared with a 51% decrease for those who underwent AC (p = 0.004). Patients who underwent AC were 9% more likely to go into remission than patients treated with DBS (p = 0.02). No difference in complication rates was noted.

Anterior capsulotomy is an efficient procedure for refractory OCD. Deep brain stimulation in the VC/VS and NAcc area is an emerging and promising therapy. The current popularity of DBS over ablative surgery for OCD is not due to nonefficacy of AC, but possibly because DBS is perceived as more acceptable by clinicians and patients.

Clinical Outcome and Mechanisms of Deep Brain Stimulation for Obsessive-Compulsive Disorder

Clinical outcome of deep brain stimulation (DBS) for obsessive-compulsive disorder (OCD) shows robust effects in terms of a mean Yale-Brown Obsessive-Compulsive Scale (YBOCS) reduction of 47.7 % and a mean response percentage (minimum 35 % YBOCS reduction) of 58.2 %. It appears that most patients regain a normal quality of life (QoL) after DBS. Reviewing the literature of the last 4 years, we argue that the mechanisms of action of DBS are a combination of excitatory and inhibitory as well as local and distal effects. Evidence from DBS animal models converges with human DBS EEG and imaging findings, in that DBS may be effective for OCD by reduction of hyperconnectivity between frontal and striatal areas. This is achieved through reduction of top-down-directed synchrony and reduction of frontal low-frequency oscillations. DBS appears to counteract striatal dysfunction through an increase in striatal dopamine and through improvement of reward processing. DBS affects anxiety levels through reduction of stress hormones and improvement of fear extinction.

Neurostimulation in Alzheimer's disease: from basic research to clinical applications

The development of different methods of brain stimulation provides a promising therapeutic tool with potentially beneficial effects on subjects with impaired cognitive functions. We performed a systematic review of the studies published in the field of neurostimulation in Alzheimer's disease (AD), from basic research to clinical applications. The main methods of non-invasive brain stimulation are repetitive transcranial magnetic stimulation and transcranial direct current stimulation. Preliminary findings have suggested that both techniques can enhance performances on several cognitive functions impaired in AD. Another non-invasive emerging neuromodulatory approach, the transcranial electromagnetic treatment, was found to reverse cognitive impairment in AD transgenic mice and even improves cognitive performance in normal mice. Experimental studies suggest that high-frequency electromagnetic fields may be critically important in AD prevention and treatment through their action at mitochondrial level. Finally, the application of a widely known invasive technique, the deep brain stimulation (DBS), has increasingly been considered as a therapeutic option also for patients with AD; it has been demonstrated that DBS of fornix/hypothalamus and nucleus basalis of Meynert might improve or at least stabilize cognitive functioning in AD. Initial encouraging results provide support for continuing to investigate non-invasive and invasive brain stimulation approaches as an adjuvant treatment for AD patients.

Current perspectives on deep brain stimulation for severe neurological and psychiatric disorders

Deep brain stimulation (DBS) has become a well-accepted therapy to treat movement disorders, including Parkinson's disease, essential tremor, and dystonia. Long-term follow-up studies have demonstrated sustained improvement in motor symptoms and quality of life. DBS offers the opportunity to selectively modulate the targeted brain regions and related networks. Moreover, stimulation can be adjusted according to individual patients' demands, and stimulation is reversible. This has led to the introduction of DBS as a treatment for further neurological and psychiatric disorders and many clinical studies investigating the efficacy of stimulating various brain regions in order to alleviate severe neurological or psychiatric disorders including epilepsy, major depression, and obsessive-compulsive disorder. In this review, we provide an overview of accepted and experimental indications for DBS therapy and the corresponding anatomical targets.

[Twiddler's syndrome in a patient with obsessive-compulsive disorder treated with deep brain stimulation]

Twiddler's syndrome is a rare complication associated with implantable electrical stimulation devices. First described in a patient with a pacemaker, it is a known complication in the field of cardiology. However, it is not so recognised in the world of neurosurgery, in which it has been described in relation to deep brain stimulation (DBS) devices. Characterised by manipulating either consciously or unconsciously the generator of such devices, which causes it to rotate on itself, the syndrome causes the coiling of the wiring of these systems and can lead to their rupture or the displacement of intracranial electrodes. We describe a case of twiddler's syndrome in a patient treated with DBS for obsessive-compulsive disorder, in which clinical deterioration presented after a good initial response. Control radiographs revealed rotation of the wiring system and displacement of the intracranial electrodes.

Electrical stimulation of the medial forebrain bundle in pre-clinical studies of psychiatric disorders

Modulating neuronal activity by electrical stimulation has expanded from the realm of motor indications into the field of psychiatric disorders in the past 10 years. The medial forebrain bundle (MFB), with a seminal role in motor, reward orientated and affect regulation behaviors, and its afferent and efferent loci, have been targeted in several DBS trials in patients with psychiatric disorders. However, little is known about the consequences of modulating the MFB in affective disorders. The paper reviews the relevant pre-clinical literature investigating electrical stimulation of regions associated with the MFB in the context of several models of psychiatric disorders, in particular depression. The clinical data is promising but limited, and pre-clinical studies are essential for improved understanding of the anatomy, the connectivity, and the consequences of stimulation of the MFB and regions associated with the neurocircuitry of psychiatric disorders. Current data suggests that the MFB is at a "privileged" position on this circuitry and its stimulation can simultaneously modulate activity at other key sites, such as the nucleus accumbens, the ventromedial prefrontal cortex or the ventral tegmental area. Future experimental work will need to shed light on the anti-depressive mechanisms of MFB stimulation in order to optimize clinical interventions.

Deep brain stimulation in the treatment of depression

Major depressive disorder is a worldwide disease with debilitating effects on a patient's life. Common treatments include pharmacotherapy, psychotherapy, and electroconvulsive therapy. Many patients do not respond to these treatments; this has led to the investigation of alternative therapeutic modalities. Deep brain stimulation (DBS) is one of these modalities. It was first used with success for treating movement disorders and has since been extended to the treatment of psychiatric disorders. Although DBS is still an emerging treatment, promising efficacy and safety have been demonstrated in preliminary trials in patients with treatment-resistant depression (TRD). Further, neuroimaging has played a pivotal role in identifying some DBS targets and remains an important tool for evaluating the mechanism of action of this novel intervention. Preclinical animal studies have broadened knowledge about the possible mechanisms of action of DBS for TRD, Given that DBS involves neurosurgery in patients with severe psychiatric impairment, ethical questions concerning capacity to consent arise; these issues must continue to be carefully considered.