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

Fiber architecture in the human ventromedial striatum and its relation with the bed nucleus of the stria terminalis

The bed nucleus of the stria terminalis (BST) and the ventromedial striatum (consisting of the head of the caudate nucleus (hCN) and the nucleus accumbens (NAcc)) are both part of complex, foremost limbic networks involved in a variety of neuropsychiatric conditions. However, data on functional or structural connections between the BST and hCN in humans are scarce. In an earlier study using both diffusion tensor magnetic resonance imaging (DTI) and conventional histology we found a pathway from the BST to the orbitofrontal cortex apparently passing directly through the hCN. To confirm this finding, we now examined the hCN in human ex-vivo brain tissue using polarized light microscopy (PLM), a method particularly suitable for depicting myelinated nerve fibers. We further examined whether differences in fiber distribution inside the hCN could be depicted using high-resolution DTI data. PLM revealed different fiber populations inside the hCN and the NAcc. Fibers in the hCN were mostly related to the anterior limb of the internal capsule (ALIC) with some apparently terminating in the hCN while the majority exited the hCN to enter the prefrontal white matter. Fibers originating from the BST were only scarcely seen on this level and appeared to either terminate inside the hCN or join the ALIC. On levels below the anterior commissure, the BST strongly connected 1) to other basal forebrain structures including the NAcc, and 2) with the white matter of the medial prefrontal cortex. Differences in fiber density within the hCN could be reproduced on MRI data but with strong interindividual variation. In summary, PLM revealed a much more complex fiber architecture in the region of interest than suggested by our earlier DTI findings. The study at hand shows that PLM can be a valuable tool for the verification of unclear or ambiguous DTI fiber tracking results.

How Long Does Deep Brain Stimulation Give Patients Benefit?

INTRODUCTION

One of the most common questions patients ask when they are contemplating deep brain stimulation (DBS) is how long it will last. To guide physicians in answering this query, we performed a scoping review to assess the current state of the literature and to identify the gaps that need to be addressed.

MATERIALS AND METHODS

The authors performed a MEDLINE search inclusive of articles from January 1987 (advent of DBS literature) to June 2023 including human and modeling studies written in English. For longevity of therapy data, only studies with a mean follow-up of ≥three years were included. Using the Rayyan platform, two reviewers (JP and RM) performed a title screen. Of the 734 articles, 205 were selected by title screen and 109 from abstract review. Ultimately, a total of 122 articles were reviewed. The research questions we explored were 1) how long can the different components of the DBS system maintain functionality? and 2) how long can DBS remain efficacious in treating Parkinson's disease (PD), essential tremor (ET), dystonia, and other disorders?

RESULTS

We showed that patients with PD, ET, and dystonia maintain a considerable long-term benefit in motor scores seven to ten years after implant, although the percentage improvement decreases over time. Stimulation off scores in PD and ET show worsening, consistent with disease progression. Battery life varies by the disease treated and the programming settings used. There remains a paucity of literature after ten years, and the impact of new device technology has not been classified to date.

CONCLUSION

We reviewed existing data on DBS longevity. Overall, outcomes data after ten years of therapy are substantially limited in the current literature. We recommend that physicians who have data for patients with DBS exceeding this duration publish their results.

Deep Brain Stimulation Response Circuits in Obsessive-Compulsive Disorder

In the field of deep brain stimulation (DBS), 2 major themes are currently making significant progress. The first of these is the framework of connectomic DBS, in which circuits that are associated with improvements of specific symptoms are described and targeted to improve and potentially personalize treatment. The second theme is related to the concept of brain sensing and adaptive DBS, which are aimed at identifying neural biomarkers that may guide stimulation in a closed-loop fashion. In DBS for obsessive-compulsive disorder (OCD), substantial progress has been made on both ends over the last 5 years. Together, the results have begun to draw a picture of exactly which circuit is associated with treatment response and how it may be affected by dysfunctional brain activity that may be attenuated using DBS. This knowledge, if further refined and validated, will define where, when, and how to stimulate which patients with OCD. We review the key studies from recent years with the aim of aggregating and condensing findings along both spatial and temporal domains. The result is a concept that anatomically defines a circuit that is likely dysfunctional in patients with typical OCD phenotypes and that may be adaptively targeted using DBS to maximally improve symptoms.

Invasive Brain Mapping Identifies Personalized Therapeutic Neuromodulation Targets for Obsessive-Compulsive Disorder

Deep brain stimulation has been used to treat severe, refractory obsessive-compulsive disorder (OCD) with variable outcomes across multiple anatomical targets. To overcome these limitations, we developed an invasive brain mapping paradigm in which electrodes were implanted across the OCD cortico-striato-thalamo-cortical circuit in a single individual. We then performed extensive stimulation mapping during a multi-day inpatient stay to identify personalized therapeutic targets and characterize their downstream circuit effects. We found two targets within the right ventral capsule (VC) that acutely reduced OCD symptoms. Prolonged VC stimulation suppressed high frequency activity within the structurally and functionally connected orbitofrontal cortex, which encoded the severity of OCD symptoms. These VC sites were implanted for DBS and combined stimulation of these targets led to a rapid therapeutic response. This case provides the first proof-of-concept that invasive brain mapping can be used to guide a novel personalized, multi-site neuromodulation approach to treat refractory OCD.

Deep brain stimulation for obsessive compulsive disorder leads to symptom changes of comorbid irritable bowel syndrome

Introduction

Irritable bowel syndrome (IBS) is a common condition characterized by abdominal pain and altered bowel habits, affecting around 11% of individuals globally. It is linked to dysregulation of the brain-gut axis, with altered activity and connectivity in various brain regions. IBS patients often have psychiatric comorbidities like anxiety, or obsessive-compulsive disorder (OCD). Deep brain stimulation (DBS) is an established treatment option for severe, therapy-refractory OCD. It has been suggested that DBS for OCD could also have a beneficial effect on accompanying IBS-symptoms.

Methods and patients

Nine patients with treatment-refractory OCD who underwent DBS in the bed nucleus striae terminalis (BNST) have been included in this study (4 males, 5 females, mean age: 39.1 ± 11.5 years). Patients were examined with the Gastrointestinal Symptom Rating Scale for Irritable Bowel Syndrome (GSRS-IBS) as well as the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) both before the beginning of DBS as well as throughout several follow-up visits for 12 months following the start of DBS.

Results

Three patients displayed clinically relevant levels of IBS-symptoms at baseline (GSRS-IBS scores at or beyond 32). All of those three patients showed a reduction of the GSRS-IBS score at the last follow-up (12-40%). For the other 6 patients, 5 of them showed also a reduction of the GSRS-IBS compared to the score at baseline. The mean score for all patients showed a descriptive trend toward score reduction throughout the study period and until the last follow up visit after 12 months. The mean Y-BOCS decreased from 31.11 at baseline to 16.50 at the last follow-up. Out of the 9 patients, 7 (78%) were considered responders with Y-BOCS scores decreasing between 37% to 74%. Moderate-to-large correlations between both scales could be observed at both the 9-month and the 12-month follow-up visit. However, none of these associations was statistically significant.

Conclusion

In this study, we found alleviation of IBS symptoms after DBS of the BNST, along with improvement in OCD symptoms. Future research using larger sample sizes should address whether the reductions are tied to the improvement of OCD symptoms or if DBS exerts positive effects on IBS independently of OCD symptoms.

Deep brain stimulation - A primer for psychiatrists

Deep Brain Stimulation is a form of neurostimulation where electrical stimulation is delivered via intracranial electrodes over specific subcortical targets. It has been increasingly used as an alternative to ablative procedures for psychiatric disorders refractory to standard treatments. This review describes the common psychiatric indications for DBS, the current evidence base, putative mechanisms, and future directions.

Deep Brain Stimulation in the Bed Nucleus of Stria Terminalis and Medial Forebrain Bundle in Two Patients With Treatment-Resistant Depression and Generalized Anxiety Disorder-A Long-Term Follow-Up

This case report presents positive outcomes from deep brain stimulation (DBS) targeting the bed nucleus of the stria terminalis (BNST) in two patients with treatment-resistant depression and generalized anxiety disorder. DBS effects in the medial forebrain bundle (MFB) area were unclear. Further research into DBS's efficacy when comorbid anxiety is present is required.

Bridging the Gap in FDA Approval for Pediatric Neuromodulation Devices

While neuromodulation devices for managing neurological conditions have significantly advanced, there remains a substantial gap in FDA-approved devices specifically designed for pediatric patients. Devices like deep brain stimulators (DBS), vagus nerve stimulators (VNS), and spinal cord stimulators (SCS) are primarily approved for adults, with few options for children. To meet pediatric needs, off-label use is common; however, unique challenges to pediatric device development-such as ethical concerns, small trial populations, and financial disincentives due to the limited market size-continue to hinder progress. This review examines these barriers to pediatric neuromodulation device development and FDA (Food and Drug Administration) approval, as well as the current efforts, such as FDA initiatives and consortia support, that address regulatory and financial challenges. Furthermore, we discuss pathways like the Humanitarian Device Exemptions and Real-World Evidence programs that aim to streamline the approval process and address unmet clinical needs in pediatric care. Addressing these barriers could expand access to effective neuromodulation treatments and improve patient care.

Case report: Non-linear evolution of oxytocin informs YBOCS changes post-DBS of the bed nucleus of the stria terminalis for treatment resistant OCD

Introduction

Obsessive-compulsive disorder (OCD) is a challenging neuropsychiatric condition with a subset of patients remaining refractory to conventional treatments. Deep brain stimulation (DBS) of the bed nucleus of the stria terminalis (BNST) has shown promise for severe, treatment-resistant OCD. This case report examines the relationship between plasma oxytocin levels and OCD symptom severity following BNST-DBS.

Methods

A 36-year-old patient with long-standing, treatment-resistant OCD underwent stereotactic implantation of DBS electrodes at the BNST. Postoperative assessments included OCD symptom severity using the Yale-Brown Obsessive Compulsive Scale (YBOCS) and plasma oxytocin levels, measured at 12 time points over three years. Longitudinal and correlational analyses were performed using linear and polynomial regression models.

Results

Non-linear trends in oxytocin levels were identified, with polynomial regression revealing a significant quadratic term, suggesting a parabolic trend. Strong positive correlations were found between changes in oxytocin levels and YBOCS total, obsession, and compulsion scores.

Conclusion

The findings suggest a significant non-linear evolution of oxytocin levels and a positive correlation with OCD symptom changes following BNST-DBS. Oxytocin levels could serve as a biomarker for DBS efficacy if this finding is replicated in larger studies.

Hereditary Patterns and Genetic Associations in Obsessive-Compulsive Disorder (OCD): Neuropsychiatric Insights, Genetic Influences, and Treatment Perspectives

Obsessive-Compulsive Disorder (OCD), a prevalent neuropsychiatric condition, affects approximately 2%-3% of the global population. This paper provides an extensive overview of OCD, detailing its clinical manifestations, neurobiological underpinnings, and therapeutic approaches. It examines OCD's classification shift in the DSM-5, the role of the cortico-striatothalamo- cortical pathway in its development, and the various factors contributing to its etiology, such as genes, environmental factors, and genetic predispositions. The challenges in diagnosing OCD and the effectiveness of both psychological and pharmacotherapeutic treatments are discussed. The paper also highlights the significant overlap between OCD and other mental health disorders, emphasizing its impact on global disability. Moreover, the role of genetic factors in OCD, including twin studies and gene association studies, is elaborated, underscoring the complex interplay of hereditary and environmental influences in its manifestation. The review further delves into the polygenic nature of OCD, illustrating how multiple genes contribute to its development, and explores the implications of genetic studies in understanding the disorder's complexity. Additionally, this research study delves into the concept of polygenic inheritance in complex diseases, highlighting the role of multiple genes in increasing OCD risk. A Genome-wide Association Study (GWAS) is employed to assess Single Nucleotide Polymorphisms (SNPs) to unearth genetic associations with OCD. This comprehensive analysis provides valuable insights into OCD's genetic landscape, paving the way for enhanced diagnostic approaches and treatment modalities.

Neurosurgery for mental conditions and pain: An historical perspective on the limits of biological determinism

Neurosurgical operations treat involuntary movement disorders (MvDs), spasticity, cranial neuralgias, cancer pain, and other selected disorders, and implantable neurostimulation or drug delivery devices relieve MvDs, epilepsy, cancer pain, and spasticity. In contrast, studies of surgery or device implantations to treat chronic noncancer pain or mental conditions have not shown consistent evidence of efficacy and safety in formal, randomized, controlled trials. The success of particular operations in a finite set of disorders remains at odds with disconfirming results in others. Despite expectations that surgery or device implants would benefit particular patients, the normalization of unproven procedures could jeopardize the perceived legitimacy of functional neurosurgery in general. An unacknowledged challenge in functional neurosurgery is the limitation of biological determinism, wherein network activity is presumed to exclusively or predominantly mediate nociception, affect, and behavior. That notion regards certain pain states and mental conditions as disorders or dysregulation of networks, which, by implication, make them amenable to surgery. Moreover, implantable devices can now detect and analyze neural activity for observation outside the body, described as the extrinsic or micro perspective. This fosters a belief that automated analyses of physiological and imaging data can unburden the treatment of selected mental conditions and pain states from psychological subjectivity and complexity and the inherent sematic ambiguity of self-reporting. That idea is appealing; however, it discounts all other influences. Attempts to sway public opinion and regulators to approve deep brain stimulation for unproven indications could, if successful, harm the public interest, making demands for regulatory approval beside the point.

Genomics of severe and treatment-resistant obsessive-compulsive disorder treated with deep brain stimulation: A preliminary investigation

Individuals with severe and treatment-resistant obsessive-compulsive disorder (trOCD) represent a small but severely disabled group of patients. Since trOCD cases eligible for deep brain stimulation (DBS) probably comprise the most severe end of the OCD spectrum, we hypothesize that they may be more likely to have a strong genetic contribution to their disorder. Therefore, while the worldwide population of DBS-treated cases may be small (~300), screening these individuals with modern genomic methods may accelerate gene discovery in OCD. As such, we have begun to collect DNA from trOCD cases who qualify for DBS, and here we report results from whole exome sequencing and microarray genotyping of our first five cases. All participants had previously received DBS in the bed nucleus of stria terminalis (BNST), with two patients responding to the surgery and one showing a partial response. Our analyses focused on gene-disruptive rare variants (GDRVs; rare, predicted-deleterious single-nucleotide variants or copy number variants overlapping protein-coding genes). Three of the five cases carried a GDRV, including a missense variant in the ion transporter domain of KCNB1, a deletion at 15q11.2, and a duplication at 15q26.1. The KCNB1 variant (hg19 chr20-47991077-C-T, NM_004975.3:c.1020G>A, p.Met340Ile) causes substitution of methionine for isoleucine in the trans-membrane region of neuronal potassium voltage-gated ion channel KV2.1. This KCNB1 substitution (Met340Ile) is located in a highly constrained region of the protein where other rare missense variants have previously been associated with neurodevelopmental disorders. The patient carrying the Met340Ile variant responded to DBS, which suggests that genetic factors could potentially be predictors of treatment response in DBS for OCD. In sum, we have established a protocol for recruiting and genomically characterizing trOCD cases. Preliminary results suggest that this will be an informative strategy for finding risk genes in OCD.

Neural decoding and feature selection methods for closed-loop control of avoidance behavior

Objective.Many psychiatric disorders involve excessive avoidant or defensive behavior, such as avoidance in anxiety and trauma disorders or defensive rituals in obsessive-compulsive disorders. Developing algorithms to predict these behaviors from local field potentials (LFPs) could serve as the foundational technology for closed-loop control of such disorders. A significant challenge is identifying the LFP features that encode these defensive behaviors.Approach.We analyzed LFP signals from the infralimbic cortex and basolateral amygdala of rats undergoing tone-shock conditioning and extinction, standard for investigating defensive behaviors. We utilized a comprehensive set of neuro-markers across spectral, temporal, and connectivity domains, employing SHapley Additive exPlanations for feature importance evaluation within Light Gradient-Boosting Machine models. Our goal was to decode three commonly studied avoidance/defensive behaviors: freezing, bar-press suppression, and motion (accelerometry), examining the impact of different features on decoding performance.Main results.Band power and band power ratio between channels emerged as optimal features across sessions. High-gamma (80-150 Hz) power, power ratios, and inter-regional correlations were more informative than other bands that are more classically linked to defensive behaviors. Focusing on highly informative features enhanced performance. Across 4 recording sessions with 16 subjects, we achieved an average coefficient of determination of 0.5357 and 0.3476, and Pearson correlation coefficients of 0.7579 and 0.6092 for accelerometry jerk and bar press rate, respectively. Utilizing only the most informative features revealed differential encoding between accelerometry and bar press rate, with the former primarily through local spectral power and the latter via inter-regional connectivity. Our methodology demonstrated remarkably low training/inference time and memory usage, requiring<310 ms for training,<0.051 ms for inference, and 16.6 kB of memory, using a single core of AMD Ryzen Threadripper PRO 5995WX CPU.Significance.Our results demonstrate the feasibility of accurately decoding defensive behaviors with minimal latency, using LFP features from neural circuits strongly linked to these behaviors. This methodology holds promise for real-time decoding to identify physiological targets in closed-loop psychiatric neuromodulation.

Establishing connectivity through microdissections of midbrain stimulation-related neural circuits

Comprehensive understanding of the neural circuits involving the ventral tegmental area is essential for elucidating the anatomofunctional mechanisms governing human behaviour, in addition to the therapeutic and adverse effects of deep brain stimulation for neuropsychiatric diseases. Although the ventral tegmental area has been targeted successfully with deep brain stimulation for different neuropsychiatric diseases, the axonal connectivity of the region is not fully understood. Here, using fibre microdissections in human cadaveric hemispheres, population-based high-definition fibre tractography and previously reported deep brain stimulation hotspots, we find that the ventral tegmental area participates in an intricate network involving the serotonergic pontine nuclei, basal ganglia, limbic system, basal forebrain and prefrontal cortex, which is implicated in the treatment of obsessive-compulsive disorder, major depressive disorder, Alzheimer's disease, cluster headaches and aggressive behaviours.

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.

Deep Brain Stimulation for Obsessive-Compulsive Disorder: Optimal Stimulation Sites

BACKGROUND

Deep brain stimulation (DBS) is a promising treatment option for treatment-refractory obsessive-compulsive disorder (OCD). Several stimulation targets have been used, mostly in and around the anterior limb of the internal capsule and ventral striatum. However, the precise target within this region remains a matter of debate.

METHODS

Here, we retrospectively studied a multicenter cohort of 82 patients with OCD who underwent DBS of the ventral capsule/ventral striatum and mapped optimal stimulation sites in this region.

RESULTS

DBS sweet-spot mapping performed on a discovery set of 58 patients revealed 2 optimal stimulation sites associated with improvements on the Yale-Brown Obsessive Compulsive Scale, one in the anterior limb of the internal capsule that overlapped with a previously identified OCD-DBS response tract and one in the region of the inferior thalamic peduncle and bed nucleus of the stria terminalis. Critically, the nucleus accumbens proper and anterior commissure were associated with beneficial but suboptimal clinical improvements. Moreover, overlap with the resulting sweet- and sour-spots significantly estimated variance in outcomes in an independent cohort of 22 patients from 2 additional DBS centers. Finally, beyond obsessive-compulsive symptoms, stimulation of the anterior site was associated with optimal outcomes for both depression and anxiety, while the posterior site was only associated with improvements in depression.

CONCLUSIONS

Our results suggest how to refine targeting of DBS in OCD and may be helpful in guiding DBS programming in existing patients.

Neural Decoding and Feature Selection Techniques for Closed-Loop Control of Defensive Behavior

Objective

Many psychiatric disorders involve excessive avoidant or defensive behavior, such as avoidance in anxiety and trauma disorders or defensive rituals in obsessive-compulsive disorders. Developing algorithms to predict these behaviors from local field potentials (LFPs) could serve as foundational technology for closed-loop control of such disorders. A significant challenge is identifying the LFP features that encode these defensive behaviors.

Approach

We analyzed LFP signals from the infralimbic cortex and basolateral amygdala of rats undergoing tone-shock conditioning and extinction, standard for investigating defensive behaviors. We utilized a comprehensive set of neuro-markers across spectral, temporal, and connectivity domains, employing SHapley Additive exPlanations for feature importance evaluation within Light Gradient-Boosting Machine models. Our goal was to decode three commonly studied avoidance/defensive behaviors: freezing, bar-press suppression, and motion (accelerometry), examining the impact of different features on decoding performance.

Main results

Band power and band power ratio between channels emerged as optimal features across sessions. High-gamma (80-150 Hz) power, power ratios, and inter-regional correlations were more informative than other bands that are more classically linked to defensive behaviors. Focusing on highly informative features enhanced performance. Across 4 recording sessions with 16 subjects, we achieved an average coefficient of determination of 0.5357 and 0.3476, and Pearson correlation coefficients of 0.7579 and 0.6092 for accelerometry jerk and bar press rate, respectively. Utilizing only the most informative features revealed differential encoding between accelerometry and bar press rate, with the former primarily through local spectral power and the latter via inter-regional connectivity. Our methodology demonstrated remarkably low time complexity, requiring <110 ms for training and <1 ms for inference.

Significance

Our results demonstrate the feasibility of accurately decoding defensive behaviors with minimal latency, using LFP features from neural circuits strongly linked to these behaviors. This methodology holds promise for real-time decoding to identify physiological targets in closed-loop psychiatric neuromodulation.

Neurosurgical neuromodulation therapy for psychiatric disorders

Psychiatric disorders are among the leading contributors to global disease burden and disability. A significant portion of patients with psychiatric disorders remain treatment-refractory to best available therapy. With insights from the neurocircuitry of psychiatric disorders and extensive experience of neuromodulation with deep brain stimulation (DBS) in movement disorders, DBS is increasingly being considered to modulate the neural network in psychiatric disorders. Currently, obsessive-compulsive disorder (OCD) is the only U.S. FDA (United States Food and Drug Administration) approved DBS indication for psychiatric disorders. Medically refractory depression, addiction, and other psychiatric disorders are being explored for DBS neuromodulation. Studies evaluating DBS for psychiatric disorders are promising but lack larger, controlled studies. This paper presents a brief review and the current state of DBS and other neurosurgical neuromodulation therapies for OCD and other psychiatric disorders. We also present a brief review of MR-guided Focused Ultrasound (MRgFUS), a novel form of neurosurgical neuromodulation, which can target deep subcortical structures similar to DBS, but in a noninvasive fashion. Early experiences of neurosurgical neuromodulation therapies, including MRgFUS neuromodulation are encouraging in psychiatric disorders; however, they remain investigational. Currently, DBS and VNS are the only FDA approved neurosurgical neuromodulation options in properly selected cases of OCD and depression, respectively.

Severe Refractory Obsessive Compulsive Disorder and Depression: Should We Consider Stereotactic Neurosurgery?

Functional neurosurgery involves modulation of activity within neural circuits that drive pathological activity. Neurologists and neurosurgeons have worked closely together, advancing the field for over a century, such that neurosurgical procedures for movement disorders are now accepted as "standard of care", benefiting hundreds of thousands of patients. As with movement disorders, some neuropsychiatric illnesses, including obsessive compulsive disorder and depression, can be framed as disorders of neural networks. Over the past two decades, evidence has accumulated that stereotactic neurosurgery can help some patients with mental disorders. Nevertheless, despite the availability of class I evidence for some interventions, there is a huge mismatch between the prevalence of severe refractory mental disorders and the number of referrals made to specialised functional neurosurgery services. This paper examines the historical trajectory of neurosurgery for movement and mental disorders. A review of neurosurgical techniques, including stereotactic radiofrequency ablation, gamma knife, deep brain stimulation, and magnetic resonance imaging guided focused ultrasound, explains the high degree of safety afforded by technological advances in the field. Evidence from clinical trials supporting functional neurosurgery for mental disorders, including obsessive compulsive disorder and depression, is presented. An improved understanding of modern functional neurosurgery should foster collaboration between psychiatry and neurosurgery, providing hope to patients whose symptoms are refractory to all other treatments.

Tractography-based DBS lead repositioning improves outcome in refractory OCD and depression

Deep brain stimulation (DBS) of the anterior limb of the internal capsule (ALIC) has been used to treat refractory obsessive-compulsive disorder (OCD) and depression, but outcomes are variable, with some patients not responding to this form of invasive neuromodulation. A lack of benefit in some patients may be due to suboptimal positioning of DBS leads. Recently, studies have suggested that specific white matter tracts within the ALIC are associated with improved outcomes. Here, we present the case of a patient who initially had a modest improvement in OCD and depressive symptoms after receiving DBS within the ALIC. Subsequently, he underwent unilateral DBS lead repositioning informed by tractography targeting the ventrolateral and medial prefrontal cortex's connection with the mediodorsal thalamus. In this patient, we also conducted post-implant and post-repositioning diffusion imaging and found that we could successfully perform tractography even with DBS leads in place. Following lead repositioning into tracts predictive of benefit, the patient reached responder criteria for his OCD, and his depression was remitted. This case illustrates that tractography can potentially be used in the evaluation and planning of lead repositioning to achieve therapeutic outcomes.

Clinical outcomes of deep brain stimulation for obsessive-compulsive disorder: Insight as a predictor of symptom changes

AIM

Deep brain stimulation (DBS) is a safe and effective treatment option for people with refractory obsessive-compulsive disorder (OCD). Yet our understanding of predictors of response and prognostic factors remains rudimentary, and long-term comprehensive follow-ups are lacking. We aim to investigate the efficacy of DBS therapy for OCD patients, and predictors of clinical response.

METHODS

Eight OCD participants underwent DBS stimulation of the nucleus accumbens (NAc) in an open-label longitudinal trial, duration of follow-up varied between 9 months and 7 years. Post-operative care involved comprehensive fine tuning of stimulation parameters and adjunct multidisciplinary therapy.

RESULTS

Six participants achieved clinical response (35% improvement in obsessions and compulsions on the Yale Brown Obsessive Compulsive Scale (YBOCS)) within 6-9 weeks, response was maintained at last follow up. On average, the YBOCS improved by 45% at last follow up. Mixed linear modeling elucidated directionality of symptom changes: insight into symptoms strongly predicted (P = 0.008) changes in symptom severity during DBS therapy, likely driven by initial changes in depression and anxiety. Precise localization of DBS leads demonstrated that responders most often had their leads (and active contacts) placed dorsal compared to non-responders, relative to the Nac.

CONCLUSION

The clinical efficacy of DBS for OCD is demonstrated, and mediators of changes in symptoms are proposed. The symptom improvements within this cohort should be seen within the context of the adjunct psychological and biopsychosocial care that implemented a shared decision-making approach, with flexible iterative DBS programming. Further research should explore the utility of insight as a clinical correlate of response. The trial was prospectively registered with the ANZCTR (ACTRN12612001142820).

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.

Closed-loop neurostimulation for the treatment of psychiatric disorders

Despite increasing prevalence and huge personal and societal burden, psychiatric diseases still lack treatments which can control symptoms for a large fraction of patients. Increasing insight into the neurobiology underlying these diseases has demonstrated wide-ranging aberrant activity and functioning in multiple brain circuits and networks. Together with varied presentation and symptoms, this makes one-size-fits-all treatment a challenge. There has been a resurgence of interest in the use of neurostimulation as a treatment for psychiatric diseases. Initial studies using continuous open-loop stimulation, in which clinicians adjusted stimulation parameters during patient visits, showed promise but also mixed results. Given the periodic nature and fluctuations of symptoms often observed in psychiatric illnesses, the use of device-driven closed-loop stimulation may provide more effective therapy. The use of a biomarker, which is correlated with specific symptoms, to deliver stimulation only during symptomatic periods allows for the personalized therapy needed for such heterogeneous disorders. Here, we provide the reader with background motivating the use of closed-loop neurostimulation for the treatment of psychiatric disorders. We review foundational studies of open- and closed-loop neurostimulation for neuropsychiatric indications, focusing on deep brain stimulation, and discuss key considerations when designing and implementing closed-loop neurostimulation.

Current perspectives on tractography-guided deep brain stimulation for the treatment of mood disorders

INTRODUCTION

Deep brain stimulation (DBS) is an emerging therapy for mood disorders, particularly treatment-resistant depression (TRD). Different brain areas implicated in depression-related brain networks have been investigated as DBS targets and variable clinical outcomes highlight the importance of target identification. Tractography has provided insight into how DBS modulates disorder-related brain networks and is being increasingly used to guide DBS for psychiatric disorders.

AREAS COVERED

In this perspective, an overview of the current state of DBS for TRD and the principles of tractography is provided. Next, a comprehensive review of DBS targets is presented with a focus on tractography. Finally, the challenges and future directions of tractography-guided DBS are discussed.

EXPERT OPINION

Tractography-guided DBS is a promising tool for improving DBS outcomes for mood disorders. Tractography is particularly useful for targeting patient-specific white matter tracts that are not visible using conventional structural MRI. Developments in tractography methods will help refine DBS targeting for TRD and may facilitate symptom-specific precision neuromodulation. Ultimately, the standardization of tractography methods will be essential to transforming DBS into an established therapy for mood disorders.

Closing the loop in psychiatric deep brain stimulation: physiology, psychometrics, and plasticity

Deep brain stimulation (DBS) is an invasive approach to precise modulation of psychiatrically relevant circuits. Although it has impressive results in open-label psychiatric trials, DBS has also struggled to scale to and pass through multi-center randomized trials. This contrasts with Parkinson disease, where DBS is an established therapy treating thousands of patients annually. The core difference between these clinical applications is the difficulty of proving target engagement, and of leveraging the wide range of possible settings (parameters) that can be programmed in a given patient's DBS. In Parkinson's, patients' symptoms change rapidly and visibly when the stimulator is tuned to the correct parameters. In psychiatry, those same changes take days to weeks, limiting a clinician's ability to explore parameter space and identify patient-specific optimal settings. I review new approaches to psychiatric target engagement, with an emphasis on major depressive disorder (MDD). Specifically, I argue that better engagement may come by focusing on the root causes of psychiatric illness: dysfunction in specific, measurable cognitive functions and in the connectivity and synchrony of distributed brain circuits. I overview recent progress in both those domains, and how it may relate to other technologies discussed in companion articles in this issue.

Stereo-EEG-guided network modulation for psychiatric disorders: Surgical considerations

BACKGROUND

Deep brain stimulation (DBS) and other neuromodulatory techniques are being increasingly utilized to treat refractory neurologic and psychiatric disorders.

OBJECTIVE

/Hypothesis: To better understand the circuit-level pathophysiology of treatment-resistant depression (TRD) and treat the network-level dysfunction inherent to this challenging disorder, we adopted an approach of inpatient intracranial monitoring borrowed from the epilepsy surgery field.

METHODS

We implanted 3 patients with 4 DBS leads (bilateral pair in both the ventral capsule/ventral striatum and subcallosal cingulate) and 10 stereo-electroencephalography (sEEG) electrodes targeting depression-relevant network regions. For surgical planning, we used an interactive, holographic visualization platform to appreciate the 3D anatomy and connectivity. In the initial surgery, we placed the DBS leads and sEEG electrodes using robotic stereotaxy. Subjects were then admitted to an inpatient monitoring unit for depression-specific neurophysiological assessments. Following these investigations, subjects returned to the OR to remove the sEEG electrodes and internalize the DBS leads to implanted pulse generators.

RESULTS

Intraoperative testing revealed positive valence responses in all 3 subjects that helped verify targeting. Given the importance of the network-based hypotheses we were testing, we required accurate adherence to the surgical plan (to engage DBS and sEEG targets) and stability of DBS lead rotational position (to ensure that stimulation field estimates of the directional leads used during inpatient monitoring were relevant chronically), both of which we confirmed (mean radial error 1.2±0.9 mm; mean rotation 3.6±2.6°).

CONCLUSION

This novel hybrid sEEG-DBS approach allows detailed study of the neurophysiological substrates of complex neuropsychiatric disorders.

Clinician Perspectives on Levels of Evidence and Oversight for Deep Brain Stimulation for Treatment-Resistant Childhood OCD

Approximately 10-20% of children with obsessive-compulsive disorder (OCD) have treatment-resistant presentations, and there is likely interest in developing interventions for this patient group, which may include deep brain stimulation (DBS). The World Society for Stereotactic and Functional Neurosurgery has argued that at least two successful randomized controlled trials should be available before DBS treatment for a psychiatric disorder is considered "established." The FDA approved DBS for adults with treatment-resistant OCD under a humanitarian device exemption (HDE) in 2009, which requires that a device be used to manage or treat a condition impacting 8,000 or fewer patients annually in the United States. DBS is currently offered to children ages 7 and older with treatment-resistant dystonia under an HDE. Ethical and empirical work are needed to evaluate whether and under what conditions it might be appropriate to offer DBS for treatment-resistant childhood OCD. To address this gap, we report qualitative data from semi-structured interviews with 25 clinicians with expertise in this area. First, we report clinician perspectives on acceptable levels of evidence to offer DBS in this patient population. Second, we describe their perspectives on institutional policies or protocols that might be needed to effectively provide care for this patient population.

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.

Intraoperative valence testing to adjudicate between ventral capsule/ventral striatum and bed nucleus of the stria terminalis target selection in deep brain stimulation for obsessive-compulsive disorder

OBJECTIVE

Deep brain stimulation (DBS) is an accepted therapy for severe, treatment-refractory obsessive-compulsive disorder (trOCD). The optimal DBS target location within the anterior limb of the internal capsule, particularly along the anterior-posterior axis, remains elusive. Empirical evidence from several studies in the past decade has suggested that the ideal target lies in the vicinity of the anterior commissure (AC), either just anterior to the AC, above the ventral striatum (VS), or just posterior to the AC, above the bed nucleus of the stria terminalis (BNST). Various methods have been utilized to optimize target selection for trOCD DBS. The authors describe their practice of planning trajectories to both the VS and BNST and adjudicating between them with awake intraoperative valence testing to individualize permanent target selection.

METHODS

Eight patients with trOCD underwent awake DBS with trajectories planned for both VS and BNST targets bilaterally. The authors intraoperatively assessed the acute effects of stimulation on mood, energy, and anxiety and implanted the trajectory with the most reliable positive valence responses and least stimulation-induced side effects. The method of intraoperative target adjudication is described, and the OCD outcome at last follow-up is reported.

RESULTS

The mean patient age at surgery was 41.25 ± 15.1 years, and the mean disease duration was 22.75 ± 10.2 years. The median preoperative Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score was 39 (range 34-40). Two patients had previously undergone capsulotomy, with insufficient response. Seven (44%) of 16 leads were moved to the second target based on intraoperative stimulation findings, 4 of them to avoid strong negative valence effects. Three patients had an asymmetric implant (1 lead in each target). All 8 patients (100%) met full response criteria, and the mean Y-BOCS score reduction across the full cohort was 51.2% ± 12.8%.

CONCLUSIONS

Planning and intraoperatively testing trajectories flanking the AC-superjacent to the VS anteriorly and to the BNST posteriorly-allowed identification of positive valence responses and acute adverse effects. Awake testing helped to select between possible trajectories and identify individually optimized targets in DBS for trOCD.

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.

Deep Brain Stimulation beyond the Clinic: Navigating the Future of Parkinson's and Alzheimer's Disease Therapy

Deep brain stimulation (DBS) is a surgical procedure that uses electrical neuromodulation to target specific regions of the brain, showing potential in the treatment of neurodegenerative disorders such as Parkinson's disease (PD) and Alzheimer's disease (AD). Despite similarities in disease pathology, DBS is currently only approved for use in PD patients, with limited literature on its effectiveness in AD. While DBS has shown promise in ameliorating brain circuits in PD, further research is needed to determine the optimal parameters for DBS and address any potential side effects. This review emphasizes the need for foundational and clinical research on DBS in different brain regions to treat AD and recommends the development of a classification system for adverse effects. Furthermore, this review suggests the use of either a low-frequency system (LFS) or high-frequency system (HFS) depending on the specific symptoms of the patient for both PD and AD.

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.

Gamma knife capsulotomy for intractable OCD: Neuroimage analysis of lesion size, location, and clinical response

Obsessive-compulsive disorder (OCD) affects 2-3% of the population. One-third of patients are poorly responsive to conventional therapies, and for a subgroup, gamma knife capsulotomy (GKC) is an option. We examined lesion characteristics in patients previously treated with GKC through well-established programs in Providence, RI (Butler Hospital/Rhode Island Hospital/Alpert Medical School of Brown University) and São Paulo, Brazil (University of São Paolo). Lesions were traced on T1 images from 26 patients who had received GKC targeting the ventral half of the anterior limb of the internal capsule (ALIC), and the masks were transformed into MNI space. Voxel-wise lesion-symptom mapping was performed to assess the influence of lesion location on Y-BOCS ratings. General linear models were built to compare the relationship between lesion size/location along different axes of the ALIC and above or below-average change in Y-BOCS ratings. Sixty-nine percent of this sample were full responders (≥35% improvement in OCD). Lesion occurrence anywhere within the targeted region was associated with clinical improvement, but modeling results demonstrated that lesions occurring posteriorly (closer to the anterior commissure) and dorsally (closer to the mid-ALIC) were associated with the greatest Y-BOCS reduction. No association was found between Y-BOCS reduction and overall lesion volume. GKC remains an effective treatment for refractory OCD. Our data suggest that continuing to target the bottom half of the ALIC in the coronal plane is likely to provide the dorsal-ventral height required to achieve optimal outcomes, as it will cover the white matter pathways relevant to change. Further analysis of individual variability will be essential for improving targeting and clinical outcomes, and potentially further reducing the lesion size necessary for beneficial outcomes.

Genomics of severe and treatment-resistant obsessive-compulsive disorder treated with deep brain stimulation: a preliminary investigation

Individuals with severe and treatment-resistant obsessive-compulsive disorder (trOCD) represent a small but severely disabled group of patients. Since trOCD cases eligible for deep brain stimulation (DBS) probably comprise the most severe end of the OCD spectrum, we hypothesize that they may be more likely to have a strong genetic contribution to their disorder. Therefore, while the worldwide population of DBS-treated cases may be small (~300), screening these individuals with modern genomic methods may accelerate gene discovery in OCD. As such, we have begun to collect DNA from trOCD cases who qualify for DBS, and here we report results from whole exome sequencing and microarray genotyping of our first five cases. All participants had previously received DBS in the bed nucleus of stria terminalis (BNST), with two patients responding to the surgery and one showing a partial response. Our analyses focused on gene-disruptive rare variants (GDRVs; rare, predicted-deleterious single-nucleotide variants or copy number variants overlapping protein-coding genes). Three of the five cases carried a GDRV, including a missense variant in the ion transporter domain of KCNB1, a deletion at 15q11.2, and a duplication at 15q26.1. The KCNB1 variant (hg19 chr20-47991077-C-T, NM_004975.3:c.1020G>A, p.Met340Ile) causes substitution of methionine for isoleucine in the trans-membrane region of neuronal potassium voltage-gated ion channel KV2.1. This KCNB1 substitution (Met340Ile) is located in a highly constrained region of the protein where other rare missense variants have previously been associated with neurodevelopmental disorders. The patient carrying the Met340Ile variant responded to DBS, which suggests that genetic factors could potentially be predictors of treatment response in DBS for OCD. In sum, we have established a protocol for recruiting and genomically characterizing trOCD cases. Preliminary results suggest that this will be an informative strategy for finding risk genes in OCD.

Neurosurgical Approaches for Treatment-Resistant Obsessive-Compulsive Disorder

Treatment-resistant obsessive-compulsive disorder (trOCD) is a severely disabling, life-threatening psychiatric disorder affecting ∼0.5% of the US population. Following the failure of multiple medical and psychotherapeutic treatment lines, patients with trOCD, like others with functional disorders, may benefit from invasive neuromodulation. Cumulative evidence suggests that disrupting abnormal hyperdirect cortico-striato-thalamo-cortical (CSTC) pathway activity offers sustainable, robust symptomatic relief in most patients. Multiple surgical approaches allow for modulation of the CSTC pathway, including stereotactic lesions and electrical stimulation. This review aims to describe the modern neurosurgical approaches for trOCD, recent advances in our understanding of pathophysiology, and future therapeutic directions.

The role of the bed nucleus of the stria terminalis in the motivational control of instrumental action

We review recent studies assessing the role of the bed nucleus of the stria terminalis (BNST) in the motivational control of instrumental conditioning. This evidence suggests that the BNST and central nucleus of the amygdala (CeA) form a circuit that modulates the ventral tegmental area (VTA) input to the nucleus accumbens core (NAc core) to control the influence of Pavlovian cues on instrumental performance. In support of these claims, we found that activity in the oval region of BNST was increased by instrumental conditioning, as indexed by phosphorylated ERK activity (Experiment 1), but that this increase was not due to exposure to the instrumental contingency or to the instrumental outcome per se (Experiment 2). Instead, BNST activity was most significantly incremented in a test conducted when the instrumental outcome was anticipated but not delivered, suggesting a role for BNST in the motivational effects of anticipated outcomes on instrumental performance. To test this claim, we examined the effect of NMDA-induced cell body lesions of the BNST on general Pavlovian-to-instrumental transfer (Experiment 3). These lesions had no effect on instrumental performance or on conditioned responding during Pavlovian conditioning to either an excitory conditioned stimulus (CS) or a neutral CS (CS0) but significantly attenuated the excitatory effect of the Pavlovian CS on instrumental performance. These data are consistent with the claim that the BNST mediates the general excitatory influence of Pavlovian cues on instrumental performance and suggest BNST activity may be central to CeA-BNST modulation of a VTA-NAc core circuit in incentive motivation.

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 population-normalized tractographic fiber atlas of the anterior limb of the internal capsule: relevance to surgical neuromodulation

OBJECTIVE

The anterior limb of the internal capsule (ALIC) is a white matter highway that connects several subcortical structures to the prefrontal cortex. Although surgical interventions in the ALIC have been used to treat a number of psychiatric illnesses, there is significant debate regarding what fibers are targeted for intervention. This debate is partially due to an incomplete understanding of connectivity in the region.

METHODS

To better understand this complex structure, the authors employed a novel tractography-based approach to examine how fibers from the thalamus and subthalamic nucleus (STN) traverse the ALIC. Furthermore, the authors analyzed connections from the medial dorsal nucleus, anterior nucleus, and ventral anterior nucleus of the thalamus.

RESULTS

The results showed that there is an organizational gradient of thalamic fibers medially and STN fibers laterally in the ALIC that fades more anteriorly. These findings, in combination with the known corticotopic organization described by previous studies, allow for a more thorough understanding of the organization of the white matter fibers in the ALIC.

CONCLUSIONS

These results are important for understanding and targeting of neuromodulatory therapies in the ALIC and may help explain why differences in therapeutic effect are observed for different areas of the ALIC.

Efficacy of deep brain stimulation for treatment-resistant obsessive-compulsive disorder: systematic review and meta-analysis

Deep brain stimulation (DBS) is an established and growing intervention for treatment-resistant obsessive-compulsive disorder (TROCD). We assessed current evidence on the efficacy of DBS in alleviating OCD and comorbid depressive symptoms including newly available evidence from recent trials and a deeper risk of bias analysis than previously available. PubMed and EMBASE databases were systematically queried using Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. We included studies reporting primary data on multiple patients who received DBS therapy with outcomes reported through the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS). Primary effect measures included Y-BOCS mean difference and per cent reduction as well as responder rate (≥35% Y-BOCS reduction) at last follow-up. Secondary effect measures included standardised depression scale reduction. Risk of bias assessments were performed on randomised controlled (RCTs) and non-randomised trials. Thirty-four studies from 2005 to 2021, 9 RCTs (n=97) and 25 non-RCTs (n=255), were included in systematic review and meta-analysis based on available outcome data. A random-effects model indicated a meta-analytical average 14.3 point or 47% reduction (p<0.01) in Y-BOCS scores without significant difference between RCTs and non-RCTs. At last follow-up, 66% of patients were full responders to DBS therapy. Sensitivity analyses indicated a low likelihood of small study effect bias in reported outcomes. Secondary analysis revealed a 1 standardised effect size (Hedges' g) reduction in depressive scale symptoms. Both RCTs and non-RCTs were determined to have a predominantly low risk of bias. A strong evidence base supports DBS for TROCD in relieving both OCD and comorbid depression symptoms in appropriately selected patients.

Deep brain stimulation in the ALIC-BNST region targeting the bed nucleus of stria terminalis in patients with obsessive-compulsive disorder: effects on cognition after 12 months

PURPOSE

The aim of this study was to evaluate cognitive effects 12 months after Deep Brain Stimulation (DBS) of the Bed Nucleus of Stria Terminalis (BNST) in patients with refractory Obsessive-Compulsive Disorder (OCD).

METHODS

Eight patients (5 female; mean ± SD age 36 ± 15) with OCD were included. A neuropsychological test battery covering verbal and spatial episodic memory, executive function, and attention was administered preoperatively and 12 months after surgery. Medical records were used as a source for descriptive data to probe for any changes not covered by standardized checklists and the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the primary outcome measure.

RESULTS

At 12 months, seven patients showed response to DBS: three were full responders (i.e., Y-BOCS ≥ 35% improvement), and four were partial responders (Y-BOCS 25-34% improvement). Relative to baseline, there was a slight decline on visuo-spatial learning (p = 0.027), and improved performance on the Color-Word Interference inhibition/switching subtest (p = 0.041), suggesting improvement in cognitive flexibility.

CONCLUSIONS

DBS in the BNST for treatment refractory OCD generates very few adverse cognitive effects and improves cognitive flexibility after 12 months of stimulation. The improvement in Y-BOCS and the absence of major cognitive side effects support the BNST as a potential target for DBS in severe OCD.

Resolving dyskinesias at sustained anti-OCD efficacy by steering of DBS away from the anteromedial STN to the mesencephalic ventral tegmentum - case report

Here we describe therapeutic results in a female patient who underwent bilateral slMFB DBS for OCD. During a 35-month long course of stimulation, she suffered from stimulation-induced dyskinesia of her right leg which we interpreted as co-stimulation of the adjacent anteromedial subthalamic nucleus (amSTN). After reprogramming to steer the stimulation away from the amSTN medial into the direction of the mesencephalic ventral tegmentum (MVT which contains the ventral tegmental area, VTA), the dyskinesias disappeared. Remarkably, anti-OCD efficacy in the presented patient was preserved and achieved with a bilateral stimulation which by our imaging study fully avoided the amSTN.

Neuromodulation of OCD: A review of invasive and non-invasive methods

Early research into neural correlates of obsessive compulsive disorder (OCD) has focused on individual components, several network-based models have emerged from more recent data on dysfunction within brain networks, including the the lateral orbitofrontal cortex (lOFC)-ventromedial caudate, limbic, salience, and default mode networks. Moreover, the interplay between multiple brain networks has been increasingly recognized. As the understanding of the neural circuitry underlying the pathophysiology of OCD continues to evolve, so will too our ability to specifically target these networks using invasive and noninvasive methods. This review discusses the rationale for and theory behind neuromodulation in the treatment of OCD.

The Dorsal Bed Nucleus of the Stria Terminalis in Depressed and Non-Depressed Temporal Lobe Epilepsy Patients

OBJECTIVES

Temporal lobe epilepsy (TLE) and depression are common comorbid disorders whose underlying shared neural network has yet to be determined. While animal studies demonstrate a role for the dorsal bed nucleus of the stria terminalis (dBNST) in both seizures and depression, and humans clinical studies demonstrate a therapeutic effect of stimulating this region on treatment-resistant depression, the role for the dBNST in depressed and non-depressed TLE patients is still unclear. Here, we tested the hypothesis that this structure is morphologically abnormal in these epilepsy patients, with an increased abnormality in TLE patients with comorbid depression.

METHODS

In this case-controlled study, three Tesla structural magnetic resonance imaging scans were obtained from TLE patients with no depression (TLEonly), with depression (TLEdep) and healthy comparison subjects (HC). TLE subjects were recruited from the Yale University Comprehensive Epilepsy Center, diagnosed with the International League Against Epilepsy 2014 Diagnostic Guidelines, and confirmed by video electroencephalography. Diagnosis of major depressive disorder was confirmed by a trained neuropsychologist through a Mini International Neuropsychiatric Interview based on the DSM-IV. The dBNST was delineated manually by reliable raters using Bioimage Suite software.

RESULTS

The number of patients and subjects included 35 TLEonly patients, 20 TLEdep patients, and 102 HC subjects. Both TLEonly and TLEdep patients had higher dBNST volumes compared to HC subjects, unilaterally in the left hemisphere in the TLEonly patients (p=0.003), and bilaterally in the TLEdep patients (p<0·0001). Furthermore, the TLEdep patients had a higher dBNST volume than the TLEonly patients in the right hemisphere (p=0.02).

SIGNIFICANCE

Here we demonstrate an abnormality of the dBNST in TLE patients, both without depression (left enlargement) and with depression (bilateral enlargement). Our results demonstrate this region to underlie both temporal lobe epilepsy with and without depression, implicating it as a target to treat the comorbidity between these two disorders.

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.