Who qualifies for deep brain stimulation for OCD? Data from a naturalistic clinical sample

Future directions in psychiatric neurosurgery: Proceedings of the 2022 American Society for Stereotactic and Functional Neurosurgery meeting on surgical neuromodulation for psychiatric disorders

OBJECTIVE

Despite advances in the treatment of psychiatric diseases, currently available therapies do not provide sufficient and durable relief for as many as 30-40% of patients. Neuromodulation, including deep brain stimulation (DBS), has emerged as a potential therapy for persistent disabling disease, however it has not yet gained widespread adoption. In 2016, the American Society for Stereotactic and Functional Neurosurgery (ASSFN) convened a meeting with leaders in the field to discuss a roadmap for the path forward. A follow-up meeting in 2022 aimed to review the current state of the field and to identify critical barriers and milestones for progress.

DESIGN

The ASSFN convened a meeting on June 3, 2022 in Atlanta, Georgia and included leaders from the fields of neurology, neurosurgery, and psychiatry along with colleagues from industry, government, ethics, and law. The goal was to review the current state of the field, assess for advances or setbacks in the interim six years, and suggest a future path forward. The participants focused on five areas of interest: interdisciplinary engagement, regulatory pathways and trial design, disease biomarkers, ethics of psychiatric surgery, and resource allocation/prioritization. The proceedings are summarized here.

CONCLUSION

The field of surgical psychiatry has made significant progress since our last expert meeting. Although weakness and threats to the development of novel surgical therapies exist, the identified strengths and opportunities promise to move the field through methodically rigorous and biologically-based approaches. The experts agree that ethics, law, patient engagement, and multidisciplinary teams will be critical to any potential growth in this area.

Patients selection for psychiatric neurosurgery: pitfalls and considerations

Neurosurgical interventions (destructive or neuromodulation) are considered as a therapeutic option for patients with treatment resistant mental disorders. However, the issues of indications and contraindications for psychiatric surgery, method and patient selection remain unresolved. This article discusses possible problems and contradictions in the selection of patients, the need for an interdisciplinary team to work to solve the question of the feasibility of using neurosurgical methods. The authors have identified the main problems that increase the risks of selection and lead to a lack of results or low efficiency of neurosurgical intervention, namely: (1) diagnostic errors or inaccuracies; (2) inconclusive data on therapeutic resistance; (3) lack of a common understanding of the goals and desired results among participants in the selection of patients for neurosurgery. Possible predictors of surgical outcome and ethical issues are also discussed. Neurosurgical interventions as a treatment option for psychiatric disorders are not officially approved in most countries. So an appropriate algorithm for patient selection and clear criteria for outcome measures are needed.

Patient-specific connectomic models correlate with, but do not reliably predict, outcomes in deep brain stimulation for obsessive-compulsive disorder

Deep brain stimulation (DBS) of the ventral internal capsule/ventral striatum (VCVS) is an emerging treatment for obsessive-compulsive disorder (OCD). Recently, multiple studies using normative connectomes have correlated DBS outcomes to stimulation of specific white matter tracts. Those studies did not test whether these correlations are clinically predictive, and did not apply cross-validation approaches that are necessary for biomarker development. Further, they did not account for the possibility of systematic differences between DBS patients and the non-diagnosed controls used in normative connectomes. To address these gaps, we performed patient-specific diffusion imaging in 8 patients who underwent VCVS DBS for OCD. We delineated tracts connecting thalamus and subthalamic nucleus (STN) to prefrontal cortex via VCVS. We then calculated which tracts were likely activated by individual patients' DBS settings. We fit multiple statistical models to predict both OCD and depression outcomes from tract activation. We further attempted to predict hypomania, a VCVS DBS complication. We assessed all models' performance on held-out test sets. With this best-practices approach, no model predicted OCD response, depression response, or hypomania above chance. Coefficient inspection partly supported prior reports, in that capture of tracts projecting to cingulate cortex was associated with both YBOCS and MADRS response. In contrast to prior reports, however, tracts connected to STN were not reliably correlated with response. Thus, patient-specific imaging and a guideline-adherent analysis were unable to identify a tractographic target with sufficient effect size to drive clinical decision-making or predict individual outcomes. These findings suggest caution in interpreting the results of normative connectome studies.

Ketamine in the Treatment of Obsessive-Compulsive Disorder: A Systematic Review

INTRODUCTION

First-line treatment for obsessive-compulsive disorder (OCD) includes exposure and response prevention behavioral therapy and serotonin reuptake inhibitors, particularly in combination. New and more effective treatments are needed, give that recent studies suggest that glutamatergic neurotransmission contributes to the pathophysiology of the disorder. In these circumstances, ketamine, as a potent N-methyl-D-aspartate receptor antagonist and glutamate modulator, offers alternative possibilities for OCD treatment.

METHODS

This systematic review aims to investigate the effects of ketamine in OCD, following the Preferred Reporting Items for Systematic Review and Meta-analyses Protocols (PRISMA-P). Searches were carried out using the PubMed/MEDLINE, Embase, and PsycINFO databases.

RESULTS

Nine articles were included, of which three were randomized controlled trials, three case reports, two open-label trials, and one a retrospective chart review. Reported data have shown a potential for fast onset of action and good tolerability of ketamine for OCD, even though the principal studies used only single-session racemic ketamine treatments, administered intravenously, and the results have been erratic. In addition, none of the available evidence demonstrates whether racemic ketamine, S-ketamine, or R-ketamine has the best efficacy in controlling OCD symptoms, and only sparse evidence suggests that a combination of ketamine and psychotherapy could benefit patients with OCD.

CONCLUSION

In order to advance clinical practice regarding the use of ketamine in treating OCD, future randomized, double-blind, placebo-controlled trials are required. These trials need to use larger samples to explore ketamine and its enantiomers, with different methods of administration, multiple sessions, and appropriate washout periods.

The Patient Lived-Experience of Ventral Capsulotomy for Obsessive-Compulsive Disorder: An Interpretive Phenomenological Analysis of Neuroablative Psychiatric Neurosurgery

Ventral Capsulotomy (VC) is a surgical intervention for treatment-resistant Obsessive-Compulsive Disorder (OCD). Despite clinical studies, little is known about patient perception and lived experience after neurosurgery for severe OCD. To examine the lived experiences of patients who have undergone VC for severe, treatment-resistant OCD through qualitative analysis. We conducted semi-structured interviews with six participants treated with VC for OCD. Interviews were analyzed using Interpretive Phenomenological Analysis. The following themes emerged: (1) After years of conventional treatments, patients felt neurosurgery was their “last hope” and described themselves as “desperate,” (2) While some described the surgery as a “supernatural experience,” patients also demonstrated understanding of the scientific procedure, its risks and potential benefits, (3) The surgical experience itself was positive or neutral, which was linked to trust in the clinical team, (4) Post-surgery, participants described months of heightened fear as they awaited lesion formation and functional improvement. (5) Patients consistently contextualized outcome in the context of their own life goals. Patients undergoing VC have positive views of this neurosurgical intervention, but psychiatric neurosurgical teams should anticipate patient discomfort with the time needed to achieve behavioral improvement following surgery and emphasize the importance of post-operative psychiatric care.

Concerns About Psychiatric Neurosurgery and How They Can Be Overcome: Recommendations for Responsible Research

Background

Psychiatric neurosurgery is experiencing a revival. Beside deep brain stimulation (DBS), several ablative neurosurgical procedures are currently in use. Each approach has a different profile of advantages and disadvantages. However, many psychiatrists, ethicists, and laypeople are sceptical about psychiatric neurosurgery.

Methods

We identify the main concerns against psychiatric neurosurgery, and discuss the extent to which they are justified and how they might be overcome. We review the evidence for the effectiveness, efficacy and safety of each approach, and discuss how this could be improved. We analyse whether and, if so, how randomised controlled trials (RCTs) can be used in the different approaches, and what alternatives are available if conducting RCTs is impossible for practical or ethical reasons. Specifically, we analyse the problem of failed RCTs after promising open-label studies.

Results

The main concerns are: (i) reservations based on historical psychosurgery, (ii) concerns about personality changes, (iii) concerns regarding localised interventions, and (iv) scepticism due to the lack of scientific evidence. Given the need for effective therapies for treatment-refractory psychiatric disorders and preliminary evidence for the effectiveness of psychiatric neurosurgery, further research is warranted and necessary. Since psychiatric neurosurgery has the potential to modify personality traits, it should be held to the highest ethical and scientific standards.

Conclusions

Psychiatric neurosurgery procedures with preliminary evidence for efficacy and an acceptable risk–benefit profile include DBS and micro- or radiosurgical anterior capsulotomy for intractable obsessive–compulsive disorder. These methods may be considered for individual treatment attempts, but multi-centre RCTs are necessary to provide reliable evidence.

Electrical deep neuromodulation in psychiatry

Addressing treatment refractoriness in psychiatric diseases is an essential public health objective. The last two decades have seen an increasing interest for deep brain stimulation (DBS) of several brain targets. In this chapter, we have reviewed the main DBS clinical trials in psychiatric diseases, mainly obsessive compulsive disorders (OCD) and depression, but also emerging research in other psychiatric disorders. While its efficacy and safety are confirmed, DBS is still not considered as standard therapy in psychiatry. However, advances in neuroimaging research combined to behavioral and electrophysiological data uniquely provided by DBS studies improve knowledge on physiopathology in these brain diseases. This will help define the optimal brain targets according to specific phenotype dimensions. Revealing the mechanisms of action and effects of DBS will support that its impact goes beyond a loco-regional brain stimulation and confirms that electrical neuromodulation influences brain networks. Added to the progress in neuromodulation technology, these insights will hopefully facilitate a more widespread application of this promising treatment. Future development of a personalized multimodal assessment of underlying dysfunctional brain networks will open new circuit-specific treatment perspectives that may facilitate better patient outcomes.

Double blind randomized controlled trial of deep brain stimulation for obsessive-compulsive disorder: Clinical trial design

Obsessive-compulsive disorder (OCD), a leading cause of disability, affects ~1–2% of the population, and can be distressing and disabling. About 1/3 of individuals demonstrate poor responsiveness to conventional treatments. A small proportion of these individuals may be deep brain stimulation (DBS) candidates. Candidacy is assessed through a multidisciplinary process including assessment of illness severity, chronicity, and functional impact. Optimization failure, despite multiple treatments, is critical during screening. Few patients nationwide are eligible for OCD DBS and thus a multi-center approach was necessary to obtain adequate sample size. The study was conducted over a six-year period and was a NIH-funded, eight-center sham-controlled trial of DBS targeting the ventral capsule/ventral striatum (VC/VS) region. There were 269 individuals who initially contacted the sites, in order to achieve 27 participants enrolled. Study enrollment required extensive review for eligibility, which was overseen by an independent advisory board. Disabling OCD had to be persistent for ≥5 years despite exhaustive medication and behavioral treatment. The final cohort was derived from a detailed consent process that included consent monitoring. Mean illness duration was 27.2 years. OCD symptom subtypes and psychiatric comorbidities varied, but all had severe disability with impaired quality of life and functioning. Participants were randomized to receive sham or active DBS for three months. Following this period, all participants received active DBS. Treatment assignment was masked to participants and raters and assessments were blinded. The final sample was consistent in demographic characteristics and clinical features when compared to other contemporary published prospective studies of OCD DBS. We report the clinical trial design, methods, and general demographics of this OCD DBS sample.

Magnetic Resonance-Guided Focused Ultrasound Surgery for Obsessive-Compulsive Disorders: Potential for use as a Novel Ablative Surgical Technique

Surgical treatment for psychiatric disorders, such as obsessive-compulsive disorder (OCD) and depression, using ablative techniques, such as cingulotomy and capsulotomy, have historically been controversial for a number of scientific, social, and ethical reasons. Recently, with the elucidation of anatomical and neurochemical substrates of brain function in healthy controls and patients with such disorders using various functional neuroimaging techniques, these criticisms are becoming less valid. Furthermore, by using new techniques, such as deep brain stimulation (DBS), and identifying more precise targets, beneficial effects and the lack of serious complications have been demonstrated in patients with psychiatric disorders. However, DBS also has many disadvantages. Currently, magnetic resonance-guided focused ultrasound surgery (MRgFUS) is used as a minimal-invasive surgical method for generating precisely placed focal thermal lesions in the brain. Here, we review surgical techniques and their potential complications, along with anterior limb of the internal capsule (ALIC) capsulotomy by radiofrequency lesioning and gamma knife radiosurgery, for the treatment of OCD and depression. We also discuss the limitations and technical issues related to ALIC capsulotomy with MRgFUS for medically refractory OCD and depression. Through this review we hope MRgFUS could be considered as a new treatment choice for refractory OCD.

Applications of focused ultrasound in the brain: from thermoablation to drug delivery

Focused ultrasound (FUS) is a disruptive medical technology, and its implementation in the clinic represents the culmination of decades of research. Lying at the convergence of physics, engineering, imaging, biology and neuroscience, FUS offers the ability to non-invasively and precisely intervene in key circuits that drive common and challenging brain conditions. The actions of FUS in the brain take many forms, ranging from transient blood-brain barrier opening and neuromodulation to permanent thermoablation. Over the past 5 years, we have seen a dramatic expansion of indications for and experience with FUS in humans, with a resultant exponential increase in academic and public interest in the technology. Applications now span the clinical spectrum in neurological and psychiatric diseases, with insights still emerging from preclinical models and human trials. In this Review, we provide a comprehensive overview of therapeutic ultrasound and its current and emerging indications in the brain. We examine the potential impact of FUS on the landscape of brain therapies as well as the challenges facing further advancement and broader adoption of this promising minimally invasive therapeutic alternative.

Obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a highly prevalent and chronic condition that is associated with substantial global disability. OCD is the key example of the 'obsessive-compulsive and related disorders', a group of conditions which are now classified together in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, and the International Classification of Diseases, 11th Revision, and which are often underdiagnosed and undertreated. In addition, OCD is an important example of a neuropsychiatric disorder in which rigorous research on phenomenology, psychobiology, pharmacotherapy and psychotherapy has contributed to better recognition, assessment and outcomes. Although OCD is a relatively homogenous disorder with similar symptom dimensions globally, individualized assessment of symptoms, the degree of insight, and the extent of comorbidity is needed. Several neurobiological mechanisms underlying OCD have been identified, including specific brain circuits that underpin OCD. In addition, laboratory models have demonstrated how cellular and molecular dysfunction underpins repetitive stereotyped behaviours, and the genetic architecture of OCD is increasingly understood. Effective treatments for OCD include serotonin reuptake inhibitors and cognitive-behavioural therapy, and neurosurgery for those with intractable symptoms. Integration of global mental health and translational neuroscience approaches could further advance knowledge on OCD and improve clinical outcomes.

Psychiatric Neurosurgery: A Survey on the Perceptions of Psychiatrists and Residents

OBJECTIVES

To evaluate the attitudes and perceptions of psychiatrists and psychiatry residents regarding neurosurgical procedures for treating psychiatric disorders and to identify potential barriers to patient referral.

METHODS

A survey consisting of 25 questions was created using SurveyMonkey and was distributed to psychiatrists and psychiatry residents in Quebec. The study was approved by the McGill University Health Center's Research Ethics Board. Descriptive statistics and Friedman's test were performed using SPSS software.

RESULTS

A total of 99 participants, including 64 residents and 35 psychiatrists, completed more than 75% of the survey and were included in data analysis. Overall, participants were significantly (p < 0.0005) more comfortable in referring patients suffering from treatment-resistant obsessive-compulsive disorder than from treatment-resistant major depressive disorder and preferred to refer patients for deep brain stimulation (DBS) rather than for anterior cingulotomy/capsulotomy (AC). Only 11.43% of psychiatrists had ever referred a patient for AC or DBS, and 34.69% of respondents felt that these procedures were dangerous. Lack of knowledge (82.83%) was viewed as the principal limiting factor, and 57.58% of respondents identified ≥6 different barriers to patient referral. The majority of participants (69.39%) were interested in improving their knowledge on psychiatric neurosurgery, and 82.65% felt that this subject should be included in the psychiatry residency curriculum.

CONCLUSION

Overall, participants acknowledged having many limitations to referring patients for neurosurgical interventions. While informative conferences discussing neuromodulation/neuroablation could easily address many barriers, further studies are required to assess how these could change attitudes and patterns of referral.

Deep brain stimulation of the internal capsule enhances human cognitive control and prefrontal cortex function

Deep brain stimulation (DBS) is a circuit-oriented treatment for mental disorders. Unfortunately, even well-conducted psychiatric DBS clinical trials have yielded inconsistent symptom relief, in part because DBS’ mechanism(s) of action are unclear. One clue to those mechanisms may lie in the efficacy of ventral internal capsule/ventral striatum (VCVS) DBS in both major depression (MDD) and obsessive-compulsive disorder (OCD). MDD and OCD both involve deficits in cognitive control. Cognitive control depends on prefrontal cortex (PFC) regions that project into the VCVS. Here, we show that VCVS DBS’ effect is explained in part by enhancement of PFC-driven cognitive control. DBS improves human subjects’ performance on a cognitive control task and increases theta (5–8Hz) oscillations in both medial and lateral PFC. The theta increase predicts subjects’ clinical outcomes. Our results suggest a possible mechanistic approach to DBS therapy, based on tuning stimulation to optimize these neurophysiologic phenomena.

Deep brain stimulation (DBS) is a promising treatment for psychiatric disorders, but its mechanism in relieving symptoms is unclear. Here, the authors show that DBS of ventral internal capsule/ventral striatum (VCVS) may act by enhancing prefrontal cortex oscillations that in turn enhance cognitive control.

Evolution of gamma knife capsulotomy for intractable obsessive-compulsive disorder

For more than half a century, stereotactic neurosurgical procedures have been available to treat patients with severe, debilitating symptoms of obsessive-compulsive disorder (OCD) that have proven refractory to extensive, appropriate pharmacological, and psychological treatment. Although reliable predictors of outcome remain elusive, the establishment of narrower selection criteria for neurosurgical candidacy, together with a better understanding of the functional neuroanatomy implicated in OCD, has resulted in improved clinical efficacy for an array of ablative and non-ablative intervention techniques targeting the cingulum, internal capsule, and other limbic regions. It was against this backdrop that gamma knife capsulotomy (GKC) for OCD was developed. In this paper, we review the history of this stereotactic radiosurgical procedure, from its inception to recent advances. We perform a systematic review of the existing literature and also provide a narrative account of the evolution of the procedure, detailing how the procedure has changed over time, and has been shaped by forces of evidence and innovation. As the procedure has evolved and adverse events have decreased considerably, favorable response rates have remained attainable for approximately one-half to two-thirds of individuals treated at experienced centers. A reduction in obsessive-compulsive symptom severity may result not only from direct modulation of OCD neural pathways but also from enhanced efficacy of pharmacological and psychological therapies working in a synergistic fashion with GKC. Possible complications include frontal lobe edema and even the rare formation of delayed radionecrotic cysts. These adverse events have become much less common with new radiation dose and targeting strategies. Detailed neuropsychological assessments from recent studies suggest that cognitive function is not impaired, and in some domains may even improve following treatment. We conclude this review with discussions covering topics essential for further progress of this therapy, including suggestions for future trial design given the unique features of GKC therapy, considerations for optimizing stereotactic targeting and dose planning using biophysical models, and the use of advanced imaging techniques to understand circuitry and predict response. GKC, and in particular its modern variant, gamma ventral capsulotomy, continues to be a reliable treatment option for selected cases of otherwise highly refractory OCD.

Obsessive-Compulsive Personality Symptoms Predict Poorer Response to Gamma Ventral Capsulotomy for Intractable OCD

Gamma ventral capsulotomy (GVC) is a radiosurgical procedure which aims to create lesions in the ventral part of the anterior limb of the internal capsule (ALIC). It has been used as a treatment option for patients with intractable obsessive-compulsive disorder (OCD) who do not respond to several first-line treatments attempts. However, changes in personality disorder symptoms after GVC have not been investigated. The aims of this study are to investigate changes in personality disorder symptoms after GVC and to search for baseline personality disorder symptoms that may predict clinical response to GVC. Fourteen treatment-intractable OCD patients who underwent GVC completed the Structured Clinical Interview for DSM-IV Personality Disorders (SCID-II) at baseline and one year after the procedure. Wilcoxon signed-rank test was performed to investigate personality disorder symptom changes before and after surgery. Linear regression models were utilized to predict treatment response, using baseline personality disorder symptoms as independent variables. We did not observe any quantitative changes in personality disorder symptoms after GVC, compared with baseline. Higher severity of obsessive-compulsive personality disorder symptoms at baseline was correlated with worse treatment response after GVC for OCD (β = -0.085, t-value = -2.52, p-value = 0.027). These findings advocate for the safety of the GVC procedure in this specific population of intractable OCD patients, in terms of personality disorder symptom changes. They also highlight the importance of taking into account the severity of obsessive-compulsive personality disorder symptoms when GVC is indicated for intractable OCD patients.

Gamma Ventral Capsulotomy in Intractable Obsessive-Compulsive Disorder

BACKGROUND

Despite the development of effective pharmacologic and cognitive behavioral treatments for obsessive-compulsive disorder (OCD), some patients continue to be treatment-refractory and severely impaired. Fiber tracts connecting orbitofrontal and dorsal anterior cingulate cortex with subcortical nuclei have been the target of neurosurgical lesions as well as deep brain stimulation in these patients. We report on the safety and efficacy of ventral gamma capsulotomy for patients with intractable OCD.

METHODS

Fifty-five patients with severely disabling, treatment-refractory OCD received bilateral lesions in the ventral portion of the anterior limb of the internal capsule over a 20-year period using the Leksell Gamma Knife. The patients were prospectively followed over 3 years with psychiatric, neurologic, and neuropsychological assessments of safety and efficacy, as well as structural neuroimaging.

RESULTS

Thirty-one of 55 patients (56%) had an improvement in the primary efficacy measure, the Yale-Brown Obsessive Compulsive Scale, of ≥35% over the 3-year follow-up period. Patients had significant improvements in depression, anxiety, quality of life, and global functioning. Patients tolerated the procedure well without significant acute adverse events. Five patients (9%) developed transient edema that required short courses of dexamethasone. Three patients (5%) developed cysts at long-term follow-up, 1 of whom developed radionecrosis resulting in an ongoing minimally conscious state.

CONCLUSIONS

Gamma Knife ventral capsulotomy is an effective radiosurgical procedure for many treatment-refractory OCD patients. A minority of patients developed cysts at long-term follow-up, 1 of whom had permanent neurological sequelae.

Deep brain stimulation for obsessive-compulsive disorder: Knowledge and concerns among psychiatrists, psychotherapists and patients

Background:

Deep brain stimulation (DBS) is under investigation for severe obsessive-compulsive disorder (OCD) resistant to other therapies. The number of implants worldwide is slowly increasing. Therefore, it is of importance to explore knowledge and concerns of this novel treatment among patients and their psychiatric healthcare contacts. This information is relevant for scientific professionals working with clinical studies for DBS for this indication. Especially, for future study designs and the creation of information targeting healthcare professionals and patients. The aim of this study was to explore the knowledge and concerns toward DBS among patients with OCD, psychiatrists, and cognitive behavioral therapists.

Methods:

The study was conducted through web-based surveys for the aimed target groups –psychiatrist, patients, and cognitive behavioral therapists. The surveys contained questions regarding previous knowledge of DBS, source of knowledge, attitudes, and concerns towards the therapy.

Results:

The main source of information was from scientific sources among psychiatrists and psychotherapists. The patient's main source of information was the media. Common concerns among the groups included complications from surgery, anesthesia, stimulation side effects, and the novelty of the treatment. Specific concerns for the groups included; personality changes mentioned by patients and psychotherapists, and ethical concerns among psychiatrists.

Conclusion:

There are challenges for DBS in OCD as identified by the participants of this study; source and quality of information, efficacy, potential adverse effects, and eligibility. In all of which the current evidence base still is limited. A broad research agenda is needed for studies going forward.

Deep brain stimulation and treatment-resistant obsessive-compulsive disorder: A systematic review

INTRODUCTION

At least 10% of patients with Obsessive-compulsive Disorder (OCD) are refractory to psychopharmacological treatment. The emergence of new technologies for the modulation of altered neuronal activity in Neurosurgery, deep brain stimulation (DBS), has enabled its use in severe and refractory OCD cases. The objective of this article is to review the current scientific evidence on the effectiveness and applicability of this technique to refractory OCD.

METHOD

We systematically reviewed the literature to identify the main characteristics of deep brain stimulation, its use and applicability as treatment for obsessive-compulsive disorder. Therefore, we reviewed PubMed/Medline, Embase and PsycINFO databases, combining the key-words 'Deep brain stimulation', 'DBS' and 'Obsessive-compulsive disorder' 'OCS'. The articles were selected by two of the authors independently, based on the abstracts, and if they described any of the main characteristics of the therapy referring to OCD: applicability; mechanism of action; brain therapeutic targets; efficacy; side-effects; co-therapies. All the information was subsequently extracted and analysed.

RESULTS

The critical analysis of the evidence shows that the use of DBS in treatment-resistant OCD is providing satisfactory results regarding efficacy, with assumable side-effects. However, there is insufficient evidence to support the use of any single brain target over another. Patient selection has to be done following analyses of risks/benefits, being advisable to individualize the decision of continuing with concomitant psychopharmacological and psychological treatments.

CONCLUSIONS

The use of DBS is still considered to be in the field of research, although it is increasingly used in refractory-OCD, producing in the majority of studies significant improvements in symptomatology, and in functionality and quality of life. It is essential to implement random and controlled studies regarding its long-term efficacy, cost-risk analyses and cost/benefit.

Long-term electrical stimulation of bed nucleus of stria terminalis for obsessive-compulsive disorder

We previously reported that bilateral electrical stimulation in the anterior limb of the internal capsule/bed nucleus of the stria terminalis (IC/BST) effectively reduces symptoms in severe treatment-resistant obsessive-compulsive disorder (OCD) patients. Here we used a linear mixed model to investigate the evolution of symptomatic and functional status of our patients (n=24) and examined if baseline variables could predict this evolution. Data were collected during routine, clinical psychiatric visits. Our analysis showed a long-term, sustained effect of electrical stimulation in the IC/BST. After a fast initial decline of OCD symptoms, these symptoms remain relatively stable. In addition, we found a strong ON/OFF effect of stimulation (e.g., due to battery depletion). Our data also show that it is not the surgical procedure but rather the electrical stimulation that drives the improvement in Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) scores. The Beck Depression Inventory (BDI) at baseline was the only predictor significantly related to the evolution of the Y-BOCS. A higher BDI at baseline seemed to be related to a smaller decrease of the Y-BOCS over time. In conclusion, electrical stimulation in the IC/BST has a fast and sustained effect on OCD and comorbid symptoms and functional status of patients.

Closed-loop neuromodulation systems: next-generation treatments for psychiatric illness

Despite deep brain stimulation's positive early results in psychiatric disorders, well-designed clinical trials have yielded inconsistent clinical outcomes. One path to more reliable benefit is closed-loop therapy: stimulation that is automatically adjusted by a device or algorithm in response to changes in the patient's electrical brain activity. These interventions may provide more precise and patient-specific treatments. This article first introduces the available closed-loop neuromodulation platforms, which have shown clinical efficacy in epilepsy and strong early results in movement disorders. It discusses the strengths and limitations of these devices in the context of psychiatric illness. It then describes emerging technologies to address these limitations, including pre-clinical developments such as wireless deep neurostimulation and genetically targeted neuromodulation. Finally, ongoing challenges and limitations for closed-loop psychiatric brain stimulation development, most notably the difficulty of identifying meaningful biomarkers for titration, are discussed. This is considered in the recently-released Research Domain Criteria (RDoC) framework, and how neuromodulation and RDoC are jointly very well suited to address the problem of treatment-resistant illness is described.

Role of the dorsal anterior cingulate cortex in obsessive-compulsive disorder: converging evidence from cognitive neuroscience and psychiatric neurosurgery

OBJECTIVE Advances in understanding the neurobiological basis of psychiatric disorders will improve the ability to refine neuromodulatory procedures for treatment-refractory patients. One of the core dysfunctions in obsessive-compulsive disorder (OCD) is a deficit in cognitive control, especially involving the dorsal anterior cingulate cortex (dACC). The authors' aim was to derive a neurobiological understanding of the successful treatment of refractory OCD with psychiatric neurosurgical procedures targeting the dACC. METHODS First, the authors systematically conducted a review of the literature on the role of the dACC in OCD by using the search terms "obsessive compulsive disorder" and "anterior cingulate." The neuroscience literature on cognitive control mechanisms in the dACC was then combined with the literature on psychiatric neurosurgical procedures targeting the dACC for the treatment of refractory OCD. RESULTS The authors reviewed 89 studies covering topics that included structural and functional neuroimaging and electrophysiology. The majority of resting-state functional neuroimaging studies demonstrated dACC hyperactivity in patients with OCD relative to that in controls, while task-based studies were more variable. Electrophysiological studies showed altered dACC-related biomarkers of cognitive control, such as error-related negativity in OCD patients. These studies were combined with the cognitive control neurophysiology literature, including the recently elaborated expected value of control theory of dACC function. The authors suggest that a central feature of OCD pathophysiology involves the generation of mis-specified cognitive control signals by the dACC, and they elaborate on this theory and provide suggestions for further study. CONCLUSIONS Although abnormalities in brain structure and function in OCD are distributed across a wide network, the dACC plays a central role. The authors propose a theory of cognitive control dysfunction in OCD that attempts to explain the therapeutic efficacy of dACC neuromodulation. This theoretical framework should help to guide further research into targeted treatments of OCD and other disorders of cognitive control.

Predictors of Hypomania During Ventral Capsule/Ventral Striatum Deep Brain Stimulation

Deep brain stimulation (DBS) of the ventral capsule/ventral striatum (VC/VS) is a novel therapy for neuropsychiatric disorders. Hypomania is a known complication of VC/VS DBS, but who is at risk is less understood. Factors such as family history, combined with details of DBS programming, might quantify that risk. The authors performed an iterative modeling procedure on a VC/VS DBS patient registry to identify key predictors. Hypomania was less common for men and for patients stimulated on the ventral right contact. It was more common with right monopolar stimulation. These findings may help to establish decision rules to reduce complications of VC/VS DBS.

Predicting course of illness in patients with severe obsessive-compulsive disorder

OBJECTIVE

Few data are available to inform clinical expectations about course and prognosis of severe obsessive-compulsive disorder (OCD). Such information is necessary to guide clinicians and to inform criteria for invasive interventions for severe and intractable OCD. This study sought to examine course and prospective predictors of a chronic course in patients with severe OCD over 5 years.

METHOD

A selected subset of adults in the Brown Longitudinal Obsessive-Compulsive Study (BLOCS) was included. Adult BLOCS participants were enrolled between 2001 and 2006. All participants in the current study (N = 113) had DSM-IV OCD diagnosis, severe OCD symptoms at baseline, and at least 1 year of follow-up data.

RESULTS

Cox proportional hazard models were used to examine the general pattern of course in the severe OCD sample based on Longitudinal Interval Follow-Up Evaluation (LIFE) psychiatric status ratings, as well as test predictors of chronically severe course. Results indicated that approximately half of patients with severe OCD at baseline had illness drop to a moderate or lower range of severity during 5 years of follow-up (50.4%) and that marked improvement was rare after 3 years of severe illness. The only unique predictor of a more chronically severe course was patient report of ever having been housebound for a week or more due to OCD symptoms (P < .05).

CONCLUSIONS

Findings of this study were 3-fold: (1) half of participants with severe OCD have symptom improvement over 5 years of follow-up, (2) the majority of participants that drop out of the severe range of symptom severity do so within the first 3 years of follow-up, and (3) patient-reported history of being housebound for 1 week or more due to OCD is a significant predictor of OCD's remaining severe over the 5-year follow-up.

Bilateral thermal capsulotomy with MR-guided focused ultrasound for patients with treatment-refractory obsessive-compulsive disorder: a proof-of-concept study

Despite optimal pharmacotherapy and cognitive-behavioral treatments, a proportion of patients with obsessive-compulsive disorder (OCD) remain refractory to treatment. Neurosurgical ablative or nondestructive stimulation procedures to treat these refractory patients have been investigated. However, despite the potential benefits of these surgical procedures, patients show significant surgery-related complications. This preliminary study investigated the use of bilateral thermal capsulotomy for patients with treatment-refractory OCD using magnetic resonance-guided focused ultrasound (MRgFUS) as a novel, minimally invasive, non-cranium-opening surgical technique. Between February and May 2013, four patients with medically refractory OCD were treated with MRgFUS to ablate the anterior limb of the internal capsule. Patients underwent comprehensive neuropsychological evaluations and imaging at baseline, 1 week, 1 month and 6 months following treatment. Outcomes were measured with the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS), the Hamilton Rating Scale for Depression (HAM-D) and the Hamilton Rating Scale for Anxiety (HAM-A), and treatment-related adverse events were evaluated. The results showed gradual improvements in Y-BOCS scores (a mean improvement of 33%) over the 6-month follow-up period, and all patients showed almost immediate and sustained improvements in depression (a mean reduction of 61.1%) and anxiety (a mean reduction of 69.4%). No patients demonstrated any side effects (physical or neuropsychological) in relation to the procedure. In addition, there were no significant differences found in the comprehensive neuropsychological test scores between the baseline and 6-month time points. This study demonstrates that bilateral thermal capsulotomy with MRgFUS can be used without inducing side effects to treat patients with medically refractory OCD. If larger trials validate the safety, effectiveness and long-term durability of this new approach, this procedure could considerably change the clinical management of treatment-refractory OCD.

Deep brain stimulation for treatment-refractory obsessive compulsive disorder: a systematic review

BACKGROUND

Obsessive-compulsive disorder is one of the most disabling of all psychiatric illnesses. Despite available pharmacological and psychotherapeutic treatments about 10% of patients remain severely affected and are considered treatment-refractory. For some of these patients deep brain stimulation offers an appropriate treatment method. The scope of this article is to review the published data and to compare different target structures and their effectiveness.

METHODS

PubMed search, last update June 2013, was conducted using the terms "deep brain stimulation" and "obsessive compulsive disorder".

RESULTS

In total 25 studies were found that reported five deep brain stimulation target structures to treat obsessive-compulsive disorder: the anterior limb of the internal capsule (five studies including 14 patients), nucleus accumbens (eight studies including 37 patients), ventral capsule/ventral striatum (four studies including 29 patients), subthalamic nucleus (five studies including 23 patients) and inferior thalamic peduncle (two studies including 6 patients). Despite the anatomical diversity, deep brain stimulation treatment results in similar response rates for the first four target structures. Inferior thalamic peduncle deep brain stimulation results in higher response rates but these results have to be interpreted with caution due to a very small number of cases. Procedure and device related adverse events are relatively low, as well as stimulation or therapy related side effects. Most stimulation related side effects are transient and decline after stimulation parameters have been changed.

CONCLUSION

Deep brain stimulation in treatment-refractory obsessive-compulsive disorder seems to be a relatively safe and promising treatment option. However, based on these studies no superior target structure could be identified. More research is needed to better understand mechanisms of action and response predictors that may help to develop a more personalized approach for these severely affected obsessive compulsive patients.