Long-term effects of subthalamic stimulation in Obsessive-Compulsive Disorder: Follow-up of a randomized controlled trial

Dual Treatment of Refractory Focal Epilepsy and Obsessive-Compulsive Disorder With Intracranial Responsive Neurostimulation

Purpose of the Review

Intracranial neurostimulation is a well-established treatment of neurologic conditions such as drug-resistant epilepsy (DRE) and movement disorders, and there is emerging evidence for using deep brain stimulation to treat obsessive-compulsive disorder (OCD) and depression. Nearly all published reports of intracranial neurostimulation have focused on implanting a single device to treat a single condition. The purpose of this review was to educate neurology clinicians on the background literature informing dual treatment of 2 comorbid neuropsychiatric conditions epilepsy and OCD, discuss ethical and logistical challenges to dual neuropsychiatric treatment with a single device, and demonstrate the promise and pitfalls of this approach through discussion of the first-in-human closed-looped responsive neurostimulator (RNS) implanted to treat both DRE (on-label) and OCD (off-label).

Recent Findings

We report the first implantation of an intracranial closed-loop neurostimulation device (the RNS system) with the primary goal of treating DRE and a secondary exploratory goal of managing treatment-refractory OCD. The RNS system detects electrophysiologic activity and delivers electrical stimulation through 1 or 2 electrodes implanted into a patient's seizure-onset zones (SOZs). In this case report, we describe a patient with treatment-refractory epilepsy and OCD where the first lead was implanted in the right superior temporal gyrus to target the most active SOZ based on stereotactic EEG (sEEG) recordings and semiology. The second lead was implanted to target the right anterior peri-insular region (a secondary SOZ on sEEG) with the distal-most contacts in the right nucleus accumbens, a putative target for OCD neurostimulation treatment. The RNS system was programmed to detect and record the unique electrophysiologic signature of both the patient's seizures and compulsions and then deliver tailored electrical pulses to disrupt the pathologic circuitry.

Summary

Dual treatment of refractory focal epilepsy and OCD with an intracranial closed-loop neurostimulation device is feasible, safe, and potentially effective. However, there are logistical challenges and ethical considerations to this novel approach to treatment, which require complex care coordination by a large multidisciplinary team.

The promise and challenges of transcranial magnetic stimulation and deep brain stimulation as therapeutic options for obsessive-compulsive disorder

INTRODUCTION

Obsessive compulsive disorder (OCD) represents a complex and often difficult to treat disorder. Pharmacological and psychotherapeutic interventions are often associated with sub-optimal outcomes, and 40-60% of patients are resistant to first line therapies and thus left with few treatment options. OCD is underpinned by aberrant neurocircuitry within cortical, striatal, and thalamic brain networks. Considering the neurocircuitry impairments that underlie OCD symptomology, neurostimulation therapies provide an opportunity to modulate psychopathology in a personalized manner. Also, by probing pathological neural networks, enhanced understanding of disease states can be obtained.

AREAS COVERED

This perspective discusses the clinical efficacy of TMS and DBS therapies, treatment access options, and considerations and challenges in managing patients. Recent scientific progress is discussed, with a focus on neurocircuitry and biopsychosocial aspects. Translational recommendations and suggestions for future research are provided.

EXPERT OPINION

There is robust evidence to support TMS and DBS as an efficacious therapy for treatment resistant OCD patients supported by an excellent safety profile and favorable health economic data. Despite a great need for alternative therapies for chronic and severe OCD patients, resistance toward neurostimulation therapies from regulatory bodies and the psychiatric community remains. The authors contend for greater access to TMS and DBS for treatment resistant OCD patients at specialized sites with appropriate clinical resources, particularly considering adjunct and follow-up care. Also, connectome targeting has shown robust predictive ability of symptom improvements and holds potential in advancing personalized neurostimulation therapies.

Implication of microbiota gut-brain axis in the manifestation of obsessive-compulsive disorder: Preclinical and clinical evidence

Recent research has highlighted the key role of gut microbiota in the development of psychiatric disorders. The adverse impact of stress, anxiety, and depression has been well documented on the commensal gut microflora. Thus, therapeutic benefits of gut microbiota-based interventions may not be avoided in central nervous system (CNS) disorders. In this review, we outline the current state of knowledge of gut microbiota with respect to obsessive-compulsive disorder (OCD). We discuss how OCD-generated changes corresponding to the key neurotransmitters, hypothalamic-pituitary-adrenal axis, and immunological and inflammatory pathways are connected with the modifications of the microbiota-gut-brain axis. Notably, administration of few probiotics such as Lactobacillus rhamnosus (ATCC 53103), Lactobacillus helveticus R0052, Bifidobacterium longum R0175, Saccharomyces boulardii, and Lactobacillus casei Shirota imparted positive effects in the management of OCD symptoms. Taken together, we suggest that the gut microbiota-directed therapeutics may open new treatment approaches for the management of OCD.

Deep brain stimulation for treatment resistant obsessive compulsive disorder; an observational study with ten patients under real-life conditions

Introduction

Obsessive-compulsive disorder (OCD) affects 2-3% of the global population, causing distress in many functioning levels. Standard treatments only lead to a partial recovery, and about 10% of the patients remain treatment-resistant. Deep brain stimulation offers a treatment option for severe, therapy-refractory OCD, with a reported response of about 60%. We report a comprehensive clinical, demographic, and treatment data for patients who were treated with DBS in our institution.

Methods

We offered DBS to patients with severe chronic treatment resistant OCD. Severity was defined as marked impairment in functioning and treatment resistance was defined as non-response to adequate trials of medications and psychotherapy. Between 2020 and 2022, 11 patients were implanted bilaterally in the bed nucleus of stria terminalis (BNST). Patients were evaluated with YBOCS, MADRS, GAF, CGI, and WHOQOL-BREF. We performed the ratings at baseline (before surgery), after implantation before the start of the stimulation, after reaching satisfactory stimulation parameters, and at follow-up visits 3, 6, 9, and 12 months after optimized stimulation.

Results

One patient has retracted his consent to publish the results of his treatment, thus we are reporting the results of 10 patients (5 males, 5 females, mean age: 37 years). Out of our 10 patients, 6 have shown a clear response indicated by a YBOCS-reduction between 42 and 100 percent at last follow-up. One further patient experienced a subjectively dramatic effect on OCD symptoms, but opted afterwards to stop the stimulation. The other 3 patients showed a slight, non-significant improvement of YBOCS between 8.8 and 21.9%. The overall mean YBOCS decreased from 28.3 at baseline to 13.3 (53% reduction) at the last follow-up. The improvement of the OCD symptoms was also accompanied by an improvement of depressive symptoms, global functioning, and quality of life.

Conclusion

Our results suggest that BNST-DBS can be effective for treatment-resistant OCD patients, as indicated by a reduction in symptoms and an overall improvement in functioning. Despite the need for additional research to define the patients' selection criteria, the most appropriate anatomical target, and the most effective stimulation parameters, improved patient access for this therapy should be established.

The current state, challenges, and future directions of deep brain stimulation for obsessive compulsive disorder

INTRODUCTION

Obsessive-compulsive disorder (OCD) is clinically and pathologically heterogenous, with symptoms often refractory to first-line treatments. Deep brain stimulation (DBS) for the treatment of refractory OCD provides an opportunity to adjust and individualize neuromodulation targeting aberrant circuitry underlying OCD. The tailoring of DBS therapy may allow precision in symptom control based on patient-specific pathology. Progress has been made in understanding the potential targets for DBS intervention; however, a consensus on an optimal target has not been agreed upon.

AREAS COVERED

A literature review of DBS for OCD was performed by querying the PubMed database. The following topics were covered: the evolution of DBS targeting in OCD, the concept of an underlying unified connectomic network, current DBS targets, challenges facing the field, and future directions which could advance personalized DBS in this challenging population.

EXPERT OPINION

To continue the increasing efficacy of DBS for OCD, we must further explore the optimal DBS response across clinical profiles and neuropsychiatric domains of OCD as well as how interventions targeting multiple points in an aberrant circuit, multiple aberrant circuits, or a connectivity hub impact clinical response. Additionally, biomarkers would be invaluable in programming adjustments and creating a closed-loop paradigm to address symptom fluctuation in daily life.

A single case report of STN-DBS for severe crack-cocaine dependence: double-blind ON vs. SHAM randomized controlled assessment

Crack-cocaine dependence is a severe condition with a high mortality rate. This single case study report details the first deep brain stimulation (DBS) trial targeting the sub-thalamic nucleus (STN) for crack-cocaine dependence. The investigation aimed to assess the effects of STN-DBS on cocaine craving and cocaine use, as well as STN-DBS safety and tolerance in this indication. In this pilot study, we performed double blind cross-over trials, with "ON-DBS" vs. "SHAM-DBS" for 1-month periods. STN-DBS failed to reduce cocaine craving and use. An episode of DBS-induced hypomania occurred after several weeks of cocaine intake at stimulation parameters previously well tolerated. Future research on cocaine dependence should be conducted after a prolonged abstinence period and/or explore novel types of stimulation patterns.

Tomographic tract tracing and data driven approaches to unravel complex 3D fiber anatomy of DBS relevant prefrontal projections to the diencephalic-mesencephalic junction in the marmoset

BACKGROUND

Understanding prefrontal cortex projections to diencephalic-mesencephalic junction (DMJ), especially to subthalamic nucleus (STN) and ventral mesencephalic tegmentum (VMT) helps our comprehension of Deep Brain Stimulation (DBS) in major depression (MD) and obsessive-compulsive disorder (OCD). Fiber routes are complex and tract tracing studies in non-human primate species (NHP) have yielded conflicting results. The superolateral medial forebrain bundle (slMFB) is a promising target for DBS in MD and OCD. It has become a focus of criticism owing to its name and its diffusion weighted-imaging based primary description.

OBJECTIVE

To investigate DMJ connectivity in NHP with a special focus on slMFB and the limbic hyperdirect pathway utilizing three-dimensional and data driven techniques.

METHODS

We performed left prefrontal adeno-associated virus - tracer based injections in the common marmoset monkey (n = 52). Histology and two-photon microscopy were integrated into a common space. Manual and data driven cluster analyses of DMJ, subthalamic nucleus and VMT together, followed by anterior tract tracing streamline (ATTS) tractography were deployed.

RESULTS

Typical pre- and supplementary motor hyperdirect connectivity was confirmed. The advanced tract tracing unraveled the complex connectivity to the DMJ. Limbic prefrontal territories directly projected to the VMT but not STN.

DISCUSSION

Intricate results of tract tracing studies warrant the application of advanced three-dimensional analyses to understand complex fiber-anatomical routes. The applied three-dimensional techniques can enhance anatomical understanding also in other regions with complex fiber anatomy.

CONCLUSION

Our work confirms slMFB anatomy and enfeebles previous misconceptions. The rigorous NHP approach strengthens the role of the slMFB as a target structure for DBS predominantly in psychiatric indications like MD and OCD.

Deep brain stimulation in obsessive-compulsive disorder: Results from meta-analysis

The aim of this work is to investigate the effectiveness of Deep Brain Stimulation (DBS) in patients with severe Obsessive Compulsive Disorder (OCD) who are resistant to pharmacological treatments, focusing on obsessive compulsive, depressive and anxiety symptoms as well as global function. A systematic review and meta-analysis including 25 studies (without language restrictions) from between 2003 and 2020 was performed. A total of 303 patients were evaluated twice (before and after DBS). After DBS treatment OCD patients with resistance to pharmacological treatments showed a significant improvement of obsessive-compulsive symptoms (25 studies; SMD=2.39; 95% CI, 1.91 to 2.87; P<0.0001), depression (9 studies; SMD= 1.19; 95%CI, 0.84 to 1.54; P<0.0001), anxiety (5 studies; SMD=1.00; 95%CI, 0.32 to 1.69; P=0.004) and functionality (7 studies; SMD=-3.51; 95%CI, -5.00 to -2.02; P=0.005) measured by the standardized scales: Yale Brown Obsessive Compulsive Scale (YBOCS), Hamilton Depression Rating Scale (HAM-D), Hamilton Anxiety Rating Scale (HAM-A) and Global Assessment of Function (GAF). Publication bias were discarded by using funnel plot. The main conclusions of this meta-analysis highlight the statistically significant effectiveness of DBS in patients with severe OCD who are resistant to conventional pharmacological treatments, underlying its role in global functioning apart from obsessive-compulsive symptoms.

A Systematic Review of Treatment Outcome Predictors in Deep Brain Stimulation for Refractory Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is a chronic and debilitating mental disorder. Deep brain stimulation (DBS) is a promising approach for refractory OCD patients. Research aiming at treatment outcome prediction is vital to provide optimized treatments for different patients. The primary purpose of this systematic review was to collect and synthesize studies on outcome prediction of OCD patients with DBS implantations in recent years. This systematic review (PROSPERO registration number: CRD42022335585) followed the PRISMA (Preferred Reporting Items for Systematic Review and Meta-analysis) guidelines. The search was conducted using three different databases with the following search terms related to OCD and DBS. We identified a total of 3814 articles, and 17 studies were included in our review. A specific tract confirmed by magnetic resonance imaging (MRI) was predictable for DBS outcome regardless of implant targets, but inconsistencies still exist. Current studies showed various ways of successful treatment prediction. However, considering the heterogeneous results, we hope that future studies will use larger cohorts and more precise approaches for predictors and establish more personalized ways of DBS surgeries.

The Efficacy and Safety of Deep Brain Stimulation of Combined Anterior Limb of Internal Capsule and Nucleus Accumbens (ALIC/NAcc-DBS) for Treatment-Refractory Obsessive-Compulsive Disorder: Protocol of a Multicenter, Randomized, and Double-Blinded Study

Backgrounds: Deep brain stimulation (DBS) is an emerging and promising therapeutic approach for treatment-refractory obsessive-compulsive disorder (OCD). The most common DBS targets include the anterior limb of internal capsule (ALIC) and nucleus accumbens (NAcc). This protocol aims to explore the efficacy and safety of the combined ALIC- and NAcc-DBS for treatment-refractory OCD. Methods: We will recruit 64 patients with refractory OCD from six centers, randomly allocate them to active and sham-stimulation groups through a three-month double-blind phase, then enter a three-month open-label phase. In the open-label stage, both groups experience real stimulation. Outcome measures: The primary outcome will be the efficacy and safety of combined ALIC- and NAcc-DBS, determined by treatment response rate between the active and sham-stimulation groups at the double-blind stage and spontaneously reported adverse events. The secondary outcomes are comparisons of change in Y–BOCS, CGI, HAMD, and HAMA scores at the third and sixth months compared to baseline between the active and sham-control groups, as well as the scores of the third month minus the sixth month between the two groups.

Deep brain stimulation for obsessive-compulsive disorder: A systematic review of worldwide experience after 20 years

BACKGROUND

Twenty years after its first use in a patient with obsessive-compulsive disorder (OCD), the results confirm that deep brain stimulation (DBS) is a promising therapy for patients with severe and resistant forms of the disorder. Nevertheless, many unknowns remain, including the optimal anatomical targets, the best stimulation parameters, the long-term (LT) effects of the therapy, and the clinical or biological factors associated with response. This systematic review of the articles published to date on DBS for OCD assesses the short and LT efficacy of the therapy and seeks to identify predictors of response.

AIM

To summarize the existing knowledge on the efficacy and tolerability of DBS in treatment-resistant OCD.

METHODS

A comprehensive search was conducted in the PubMed, Cochrane, Scopus, and ClinicalTrials.gov databases from inception to December 31, 2020, using the following strategy: “(Obsessive-compulsive disorder OR OCD) AND (deep brain stimulation OR DBS).” Clinical trials and observational studies published in English and evaluating the effectiveness of DBS for OCD in humans were included and screened for relevant information using a standardized collection tool. The inclusion criteria were as follows: a main diagnosis of OCD, DBS conducted for therapeutic purposes and variation in symptoms of OCD measured by the Yale-Brown Obsessive-Compulsive scale (Y-BOCS) as primary outcome. Data were analyzed with descriptive statistics.

RESULTS

Forty articles identified by the search strategy met the eligibility criteria. Applying a follow-up threshold of 36 mo, 29 studies (with 230 patients) provided information on short-term (ST) response to DBS in, while 11 (with 155 patients) reported results on LT response. Mean follow-up period was 18.5 ± 8.0 mo for the ST studies and 63.7 ± 20.7 mo for the LT studies. Overall, the percentage of reduction in Y-BOCS scores was similar in ST (47.4%) and LT responses (47.2%) to DBS, but more patients in the LT reports met the criteria for response (defined as a reduction in Y-BOCS scores > 35%: ST, 60.6% vs LT, 70.7%). According to the results, the response in the first year predicts the extent to which an OCD patient will benefit from DBS, since the maximum symptom reduction was achieved in most responders in the first 12-14 mo after implantation. Reports indicate a consistent tendency for this early improvement to be maintained to the mid-term for most patients; but it is still controversial whether this improvement persists, increases or decreases in the long term. Three different patterns of LT response emerged from the analysis: 49.5% of patients had good and sustained response to DBS, 26.6% were non responders, and 22.5% were partial responders, who might improve at some point but experience relapses during follow-up. A significant improvement in depressive symptoms and global functionality was observed in most studies, usually (although not always) in parallel with an improvement in obsessive symptoms. Most adverse effects of DBS were mild and transient and improved after adjusting stimulation parameters; however, some severe adverse events including intracranial hemorrhages and infections were also described. Hypomania was the most frequently reported psychiatric side effect. The relationship between DBS and suicide risk is still controversial and requires further study. Finally, to date, no clear clinical or biological predictors of response can be established, probably because of the differences between studies in terms of the neuroanatomical targets and stimulation protocols assessed.

CONCLUSION

The present review confirms that DBS is a promising therapy for patients with severe resistant OCD, providing both ST and LT evidence of efficacy.

Therapeutic Neurostimulation in Obsessive-Compulsive and Related Disorders: A Systematic Review

Invasive and noninvasive neurostimulation therapies for obsessive-compulsive and related disorders (OCRD) were systematically reviewed with the aim of assessing clinical characteristics, methodologies, neuroanatomical substrates, and varied stimulation parameters. Previous reviews have focused on a narrow scope, statistical rather than clinical significance, grouped together heterogenous protocols, and proposed inconclusive outcomes and directions. Herein, a comprehensive and transdiagnostic evaluation of all clinically relevant determinants is presented with translational clinical recommendations and novel response rates. Electroconvulsive therapy (ECT) studies were limited in number and quality but demonstrated greater efficacy than previously identified. Targeting the pre-SMA/SMA is recommended for transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS). TMS yielded superior outcomes, although polarity findings were conflicting, and refinement of frontal/cognitive control protocols may optimize outcomes. For both techniques, standardization of polarity, more treatment sessions (>20), and targeting multiple structures are encouraged. A deep brain stimulation (DBS) 'sweet spot' of the striatum for OCD was proposed, and CBT is strongly encouraged. Tourette's patients showed less variance and reliance on treatment optimization. Several DBS targets achieved consistent, rapid, and sustained clinical response. Analysis of fiber connectivity, as opposed to precise neural regions, should be implemented for target selection. Standardization of protocols is necessary to achieve translational outcomes.

Identification of biomarkers that predict response to subthalamic nucleus deep brain stimulation in resistant obsessive-compulsive disorder: protocol for an open-label follow-up study

INTRODUCTION

Deep brain stimulation (DBS) of bilateral anteromedial subthalamic nucleus (amSTN) has been found to be helpful in a subset of patients with severe, chronic and treatment-refractory obsessive-compulsive disorder (OCD). Biomarkers may aid in patient selection and optimisation of this invasive treatment. In this trial, we intend to evaluate neurocognitive function related to STN and related biosignatures as potential biomarkers for STN DBS in OCD.

METHODS AND ANALYSIS

Twenty-four subjects with treatment-refractory OCD will undergo open-label STN DBS. Structural/functional imaging, electrophysiological recording and neurocognitive assessment would be performed at baseline. The subjects would undergo a structured clinical assessment for 12 months postsurgery. A group of 24 healthy volunteers and 24 subjects with treatment-refractory OCD who receive treatment as usual would be recruited for comparison of biomarkers and treatment response, respectively. Baseline biomarkers would be evaluated as predictors of clinical response. Neuroadaptive changes would be studied through a reassessment of neurocognitive functioning, imaging and electrophysiological activity post DBS.

ETHICS AND DISSEMINATION

The protocol has been approved by the National Institute of Mental Health and Neurosciences Ethics Committee. The study findings will be disseminated through peer-reviewed scientific journals and scientific meetings.

Deep brain stimulation versus ablative surgery for treatment-refractory obsessive-compulsive disorder: A meta-analysis

OBJECTIVE

Ablative surgery (ABL) and deep brain stimulation (DBS) are last-resort treatment options for patients suffering from treatment-refractory obsessive-compulsive disorder (OCD). The aim of this study was to conduct an updated meta-analysis comparing the clinical outcomes of the ablative procedures capsulotomy and cingulotomy and deep brain stimulation.

METHODS

We conducted a PubMed search to identify all clinical trials on capsulotomy, cingulotomy, and DBS. Random effects meta-analyses were performed on 38 articles with a primary focus on efficacy in reducing OCD symptoms as measured by a reduction in the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) score and the responder rate (≥35% reduction in Y-BOCS score).

RESULTS

With responder rates of 48% and 53% after 12-16 months and 56% and 57% at last follow-up for ABL and DBS, respectively, and large effect sizes in the reduction in Y-BOCS scores, both surgical modalities show effectiveness in treating refractory OCD. Meta-regression did not show a statistically significant difference between ABL and DBS regarding these outcomes. Regarding adverse events, a statistically significant higher rate of impulsivity is reported in studies on DBS.

CONCLUSION

This meta-analysis shows equal efficacy of ABL and DBS in the treatment of refractory OCD. For now, the choice of intervention should, therefore, rely on factors such as risk of developing impulsivity, patient preferences, and experiences of psychiatrist and neurosurgeon. Future research should provide more insight regarding differences between ABL and DBS and response prediction following direct comparisons between the surgical modalities, to enable personalized and legitimate choices between ABL and DBS.

The Decline of Deep Brain Stimulation for Obsessive-Compulsive Disorder Following FDA Humanitarian Device Exemption Approval

Background: In February 2009, the US Food and Drug Administration (FDA) granted Humanitarian Device Exemption (HDE) for deep brain stimulation (DBS) in the anterior limb of the internal capsule (ALIC) for the treatment of severely debilitating, treatment refractory obsessive–compulsive disorder (OCD). Despite its promise as a life altering treatment for patients with otherwise refractory, severely debilitating OCD, the use of DBS for the treatment of OCD has diminished since the FDA HDE endorsement and is now rarely performed even at busy referral centers. We sought to identify factors hindering OCD patients from receiving DBS therapy.

Materials and Methods: University of Florida (UF) clinical research databases were queried to identify patients evaluated as potential candidates for OCD DBS from January 1, 2002 to July 30, 2020. A retrospective review of these patients' medical records was performed to obtain demographic information, data related to their OCD, and details relevant to payment such as third-party payer, study participation, evaluation prior to or after HDE approval, and any stated factors prohibiting surgical intervention.

Results: Out of 25 patients with severe OCD identified as candidates for DBS surgery during the past 18 years, 15 underwent surgery. Prior to FDA HDE approval, 6 out of 7 identified candidates were treated. After the HDE, only 9 out of 18 identified candidates were treated. Seven of the 9 were funded by Medicare, 1 paid out of pocket, and 1 had “pre-authorization” from her private insurer who ultimately refused to pay after the procedure. Among the 10 identified OCD DBS candidates who were ultimately not treated, 7 patients—all with private health insurance—were approved for surgery by the interdisciplinary team but were unable to proceed with surgery due to lack of insurance coverage, 1 decided against surgical intervention, 1 was excluded due to medical comorbidities and excessive perceived surgical risk, and no clear reason was identified for 1 patient evaluated in 2004 during our initial NIH OCD DBS trial.

Conclusion: Based on compelling evidence that DBS provides substantial improvement of OCD symptoms and markedly improved functional capacity in 2 out of 3 patients with severely debilitating, treatment refractory OCD, the FDA approved this procedure under a Humanitarian Device Exemption in 2009, offering new hope to this unfortunate patient population. A careful review of our experience with OCD DBS at the University of Florida shows that since the HDE approval, only 50% of the severe OCD patients (9 of 18) identified as candidates for this potentially life altering treatment have been able to access the therapy. We found the most common limiting factor to be failure of private insurance policies to cover DBS for OCD, despite readily covering DBS for Parkinson's disease, essential tremor, and even dystonia—another HDE approved indication for DBS. We have identified an inherent discrimination in the US healthcare system against patients with medication-refractory OCD who are economically challenged and do not qualify for Medicare. We urge policy makers, insurance companies, and hospital administrations to recognize this health care disparity and seek to rectify it.

Oscillatory activity in the BNST/ALIC and the frontal cortex in OCD: acute effects of DBS

Deep brain stimulation (DBS) of the bed nucleus of the stria terminalis/anterior limb of the internal capsule (BNST/ALIC) is successfully used for treatment of patients with obsessive-compulsive disorder (OCD). Clinical and experimental studies have suggested that enhanced network synchronization in the theta band is correlated with severity of symptoms. The mechanisms of action of DBS remain unclear in OCD. We here investigate the effect of acute stimulation of the BNCT/ALIC on oscillatory neuronal activity in patients with OCD implanted with DBS electrodes. We recorded the oscillatory activity of local field potentials (LFPs) from DBS electrodes (contact + 0/- 3; bipolar configuration; both hemispheres) from the BNST/ALIC parallel with frontal cortical electroencephalogram (EEG) one day after DBS surgery in four patients with OCD. BNST/ALIC and frontal EEG oscillatory activities were analysed before stimulation as baseline, and after three periods of stimulation with different voltage amplitudes (1 V, 2 V and 3.5 V) at 130 Hz. Overall, acute high frequency DBS reduced oscillatory theta band (4-8 Hz; p < 0.01) but increased other frequency bands in BNST/ALIC and the frontal cortex (p < 0.01). We show that stimulation of the BNST/ALIC in OCD modulates oscillatory activity in brain regions that are involved in the pathomechanisms of OCD. Our findings confirm and extend the findings that enhanced theta oscillatory activity in neuronal networks may be a biomarker for OCD.

Optimizing Deep Brain Stimulation Parameters in Obsessive-Compulsive Disorder

OBJECTIVES

Deep brain stimulation (DBS) is an innovative and effective treatment for patients with therapy-refractory obsessive-compulsive disorder (OCD). DBS offers unique opportunities for personalized care, but no guidelines on how to choose effective and safe stimulation parameters in patients with OCD are available. Our group gained relevant practical knowledge on DBS optimization by treating more than 80 OCD patients since 2005, the world's largest cohort. The article's objective is to share this experience.

MATERIALS AND METHODS

We provide guiding principles for optimizing DBS stimulation parameters in OCD and discuss the neurobiological and clinical basis.

RESULTS

Adjustments in stimulation parameters are performed in a fixed order. First, electrode contact activation is determined by the position of the electrodes on postoperative imaging. Second, voltage and pulse width are increased stepwise, enlarging both the chance of symptom reduction and of inducing side effects. Clinical evaluation of adjustments in stimulation parameters needs to take into account: 1) the particular temporal sequence in which the various OCD symptoms and DBS side-effects change; 2) the lack of robust response predictors; 3) the limited sensitivity of the Yale-Brown Obsessive-Compulsive Scale to assess DBS-induced changes in OCD symptoms; and 4) a patient's fitness for additional cognitive-behavioral therapy (CBT).

CONCLUSIONS

Decision-making in stimulation parameter optimization needs to be sensitive to the particular time-courses on which various symptoms and side effects change.

Invasive and Non-invasive Neurostimulation for OCD

It becomes increasingly clear that (non-)invasive neurostimulation is an effective treatment for obsessive-compulsive disorder (OCD). In this chapter we review the available evidence on techniques and targets, clinical results including a meta-analysis, mechanisms of action, and animal research. We focus on deep brain stimulation (DBS), but also cover non-invasive neurostimulation including transcranial magnetic stimulation (TMS). Data shows that most DBS studies target the ventral capsule/ventral striatum (VC/VS), with an overall 76% response rate in treatment-refractory OCD. Also TMS holds clinical promise. Increased insight in the normalizing effects of neurostimulation on cortico-striatal-thalamic-cortical (CSTC) loops - through neuroimaging and animal research - provides novel opportunities to further optimize treatment strategies. Advancing clinical implementation of neurostimulation techniques is essential to ameliorate the lives of the many treatment-refractory OCD patients.

Deep brain stimulation of the subthalamic nucleus in obsessive-compulsives disorders: long-term follow-up of an open, prospective, observational cohort

BACKGROUND

Obsessive-compulsive disorder (OCD) is a major cause of disability in western country and responsible for severe impairment of quality of life. About 10% of patients present with severe OCD symptoms and require innovative treatment such as deep brain stimulation (DBS). Among possible targets, the non-motor subthalamic nucleus (STN) is a key node of the basal ganglia circuitry, strongly connected to limbic cortical areas known to be involved in OCD.

METHOD

We analysed, in a prospective, observational, monocentric, open label cohort, the effect of chronic non-motor STN-DBS in 19 patients with treatment-resistant OCD consecutively operated in a single centre. Severity of OCD was evaluated using the Yale and Brown Obsessive-Compulsive Scale (YBOCS). YBOCS scores at 6, 12 and 24 months postoperatively were compared with baseline. Responders were defined by >35% improvement of YBOCS scores. Global Assessment Functioning (GAF) scale was used to evaluate the impact of improvement.

RESULTS

At a 24-month follow-up, the mean YBOCS score improved by 53.4% from 33.3±3.5 to 15.8±9.1 (95% CI 11.2-20.4; p<0.0001). Fourteen out of 19 patients were considered as responders, 5 out of 19 being improved over 75% and 10 out of 19 over 50%. GAF scale improved by 92% from 34.1±3.9 to 66.4±18.8 (95% CI 56.7-76.1; p=0.0003). The most frequent adverse events consisted of transient DBS-induced hypomania and anxiety.

CONCLUSION

Chronic DBS of the non-motor STN is an effective and relatively safe procedure to treat severe OCD resistant to conventional management.

Long-Term Deep Brain Stimulation in Treatment-Resistant Obsessive-Compulsive Disorder: Outcome and Quality of Life at Four to Eight Years Follow-Up

BACKGROUND

Obsessive compulsive disorder (OCD) is a severe disabling disease, and around 10% of patients are considered to be treatment-resistant (tr) in spite of guideline-based therapy. Deep brain stimulation (DBS) has been proposed as a promising treatment for patients with trOCD. However, the optimal site for stimulation is still a matter of debate, and clinical long-term follow-up observations including data on quality of life are sparse. We here present six trOCD patients who underwent DBS with electrodes placed in the bed nucleus of the stria terminalis/anterior limb of the internal capsule (BNST/ALIC), followed for four to eight years after lead implantation.

MATERIALS AND METHODS

In this prospective observational study, six patients (four men, two women) aged 32-51 years and suffering from severe to extreme trOCD underwent DBS of the BNST/ALIC. Symptom severity was assessed using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), and quality of life using the World Health Organization Quality of Life assessment scale (WHO-QoL BREF). Follow-up was obtained at least for four years in all patients.

RESULTS

With chronic DBS for four to eight years, four of the six patients had sustained improvement. Two patients remitted and two patients responded (defined as >35% symptom reduction), while the other two patients were considered nonresponders on long-term. Quality of life markedly improved in remitters and responders. We did not observe peri-interventional side effects or adverse effects of chronic stimulation.

CONCLUSIONS

Chronic DBS of ALIC provides long-term benefit up to four to eight years in trOCD, although not all patients take profit. Targeting the BNST was not particularly relevant since no patient appeared to benefit from direct stimulation of the BNST. Quality of life improved in DBS responders, documented by improved QoL scores and, even more important, by regaining of autonomy and improving psychosocial functioning.

Improving long term patient outcomes from deep brain stimulation for treatment-refractory obsessive-compulsive disorder

Introduction: Deep brain stimulation (DBS) has emerged as an effective treatment for patients with severe treatment-refractory obsessive-compulsive disorder (OCD). Over the past two decades, several clinical trials with multiple years of follow-up have shown that DBS offers long-term symptom relief for individuals with severe OCD, though a portion of patients do not achieve an adequate response.Areas covered: This review sought to summarize the literature on the efficacy and long-term effectiveness of DBS for OCD, and to identify strategies that have the potential to improve treatment outcomes.Expert opinion: Although this literature is just emerging, a small number of DBS enhancement strategies have shown promising initial results. More posterior targets along the striatal axis and at the bed nucleus of the stria terminalis appear to offer greater symptom relief than more anterior targets. Research is also beginning to demonstrate the feasibility of maximizing treatment outcomes with target selection based on neural activation patterns during symptom provocation and clinical presentation. Finally, integrating DBS with post-surgery exposure and response prevention therapy appears to be another promising approach. Definitive conclusions about these strategies are limited by a low number of studies with small sample sizes that will require multi-site replication.

Deep Brain Stimulation for Refractory Obsessive-Compulsive Disorder: Towards an Individualized Approach

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder featuring repetitive intrusive thoughts and behaviors associated with a significant handicap. Of patients, 20% are refractory to medication and cognitive behavioral therapy. Refractory OCD is associated with suicidal behavior and significant degradation of social and professional functioning, with high health costs. Deep brain stimulation (DBS) has been proposed as a reversible and controllable method to treat refractory patients, with meta-analyses showing 60% response rate following DBS, whatever the target: anterior limb of the internal capsule (ALIC), ventral capsule/ventral striatum (VC/VS), nucleus accumbens (NAcc), anteromedial subthalamic nucleus (amSTN), or inferior thalamic peduncle (ITP). But how do we choose the "best" target? Functional neuroimaging studies have shown that ALIC-DBS requires the modulation of the fiber tract within the ventral ALIC via the ventral striatum, bordering the bed nucleus of the stria terminalis and connecting the medial prefrontal cortex with the thalamus to be successful. VC/VS effective sites of stimulation were found within the VC and primarily connected to the medial orbitofrontal cortex (OFC) dorsomedial thalamus, amygdala, and the habenula. NAcc-DBS has been found to reduce OCD symptoms by decreasing excessive fronto-striatal connectivity between NAcc and the lateral and medial prefrontal cortex. The amSTN effective stimulation sites are located at the inferior medial border of the STN, primarily connected to lateral OFC, dorsal anterior cingulate, and dorsolateral prefrontal cortex. Finally, ITP-DBS recruits a bidirectional fiber pathway between the OFC and the thalamus. Thus, these functional connectivity studies show that the various DBS targets lie within the same diseased neural network. They share similar efficacy profiles on OCD symptoms as estimated on the Y-BOCS, the amSTN being the target supported by the strongest evidence in the literature. VC/VS-DBS, amSTN-DBS, and ALIC-DBS were also found to improve mood, behavioral adaptability and potentially both, respectively. Because OCD is such a heterogeneous disease with many different symptom dimensions, the ultimate aim should be to find the most appropriate DBS target for a given refractory patient. This quest will benefit from further investigation and understanding of the individual functional connectivity of OCD patients.