Differences in metabolic network modulation between capsulotomy and deep-brain stimulation for refractory obsessive-compulsive disorder

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.

Whole brain network effects of subcallosal cingulate deep brain stimulation for treatment-resistant depression

Ongoing experimental studies of subcallosal cingulate deep brain stimulation (SCC DBS) for treatment-resistant depression (TRD) show a differential timeline of behavioral effects with rapid changes after initial stimulation, and both early and delayed changes over the course of ongoing chronic stimulation. This study examined the longitudinal resting-state regional cerebral blood flow (rCBF) changes in intrinsic connectivity networks (ICNs) with SCC DBS for TRD over 6 months and repeated the same analysis by glucose metabolite changes in a new cohort. A total of twenty-two patients with TRD, 17 [15 O]-water and 5 [18 F]-fluorodeoxyglucose (FDG) positron emission tomography (PET) patients, received SCC DBS and were followed weekly for 7 months. PET scans were collected at 4-time points: baseline, 1-month after surgery, and 1 and 6 months of chronic stimulation. A linear mixed model was conducted to examine the differential trajectory of rCBF changes over time. Post-hoc tests were also examined to assess postoperative, early, and late ICN changes and response-specific effects. SCC DBS had significant time-specific effects in the salience network (SN) and the default mode network (DMN). The rCBF in SN and DMN was decreased after surgery, but responder and non-responders diverged thereafter, with a net increase in DMN activity in responders with chronic stimulation. Additionally, the rCBF in the DMN uniquely correlated with depression severity. The glucose metabolic changes in a second cohort show the same DMN changes. The trajectory of PET changes with SCC DBS is not linear, consistent with the chronology of therapeutic effects. These data provide novel evidence of both an acute reset and ongoing plastic effects in the DMN that may provide future biomarkers to track clinical improvement with ongoing treatment.

Neuroablative Intervention for Refractory Obsessive-Compulsive Disorder

OBJECTIVE

This review aims to investigate the progression of neuroablation, along with documented clinical efficacy and safety, in the management of treatment-resistant obsessive-compulsive disorder (OCD).

METHODS

We searched and compiled clinical research results of neuroablation therapy reported to date. We extracted outcomes related to clinical efficacy, side effects, and surgical complications. Additionally, we summarized key claims and findings.

RESULTS

Neuroablative intervention is a potential treatment approach for refractory OCD. Recent advancements, such as real-time magnetic resonance monitoring and minimally invasive techniques employing ultrasound and laser, offer distinct advantages in terms of safety and comparative efficacy when compared to conventional methods. However, the absence of randomized controlled trials and long-term outcome data underscores the need for cautious consideration when selecting neuroablation.

CONCLUSION

Neuroablative intervention shows promise for refractory OCD, but vigilant consideration is essential in both patient selection and surgical method choices due to the potential for rare yet serious complications.

Thirty Years of Global Deep Brain Stimulation: "Plus ça change, plus c'est la même chose"?

BACKGROUND

The advent of deep brain stimulation (DBS) of the subthalamic nucleus (STN) for Parkinson's disease 30 years ago has ushered a global breakthrough of DBS as a universal method for therapy and research in wide areas of neurology and psychiatry. The literature of the last three decades has described numerous concepts and practices of DBS, often branded as novelties or discoveries. However, reading the contemporary publications often elicits a sense of déjà vu in relation to several methods, attributes, and practices of DBS. Here, we review various applications and techniques of the modern-era DBS and compare them with practices of the past.

SUMMARY

Compared with modern literature, publications of the old-era functional stereotactic neurosurgery, including old-era DBS, show that from the very beginning multidisciplinarity and teamwork were often prevalent and insisted upon, ethical concerns were recognized, brain circuitries and rational for brain targets were discussed, surgical indications were similar, closed-loop stimulation was attempted, evaluations of surgical results were debated, and controversies were common. Thus, it appears that virtually everything done today in the field of DBS bears resemblance to old-time practices, or has been done before, albeit with partly other tools and techniques. Movement disorders remain the main indications for modern DBS as was the case for lesional surgery and old-era DBS. The novelties today consist of the STN as the dominant target for DBS, the tremendous advances in computerized brain imaging, the sophistication and versatility of implantable DBS hardware, and the large potential for research.

KEY MESSAGES

Many aspects of contemporary DBS bear strong resemblance to practices of the past. The dominant clinical indications remain movement disorders with virtually the same brain targets as in the past, with one exception: the STN. Other novel brain targets - that are so far subject to DBS trials - are the pedunculopontine nucleus for gait freezing, the anteromedial internal pallidum for Gilles de la Tourette and the fornix for Alzheimer's disease. The major innovations and novelties compared to the past concern mainly the unmatched level of research activity, its high degree of sponsorship, and the outstanding advances in technology that have enabled multimodal brain imaging and the miniaturization, versatility, and sophistication of implantable hardware. The greatest benefit for patients today, compared to the past, is the higher level of precision and safety of DBS, and of all functional stereotactic neurosurgery.

Dissecting Psychiatric Heterogeneity and Comorbidity with Core Region-Based Machine Learning

Machine learning approaches are increasingly being applied to neuroimaging data from patients with psychiatric disorders to extract brain-based features for diagnosis and prognosis. The goal of this review is to discuss recent practices for evaluating machine learning applications to obsessive-compulsive and related disorders and to advance a novel strategy of building machine learning models based on a set of core brain regions for better performance, interpretability, and generalizability. Specifically, we argue that a core set of co-altered brain regions (namely 'core regions') comprising areas central to the underlying psychopathology enables the efficient construction of a predictive model to identify distinct symptom dimensions/clusters in individual patients. Hypothesis-driven and data-driven approaches are further introduced showing how core regions are identified from the entire brain. We demonstrate a broadly applicable roadmap for leveraging this core set-based strategy to accelerate the pursuit of neuroimaging-based markers for diagnosis and prognosis in a variety of psychiatric disorders.

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.

Whole Brain Network effects of subcallosal cingulate deep brain stimulation for treatment-resistant depression

Ongoing experimental studies of subcallosal cingulate deep brain stimulation (SCC DBS) for treatment-resistant depression (TRD) show a differential timeline of behavioral effects with rapid changes after initial stimulation, and both early and delayed changes over the course of ongoing chronic stimulation. This study examined the longitudinal resting-state regional cerebral blood ow (rCBF) changes in intrinsic connectivity networks (ICNs) with SCC DBS for TRD over 6 months and repeated the same analysis by glucose metabolite changes in a new cohort. A total of twenty-two patients with TRD, 17 [15O]-water and 5 [18]-Fluorodeoxyglucose (FDG) positron emission tomography (PET) patients, received SCC DBS and were followed weekly for 7 months. PET scans were collected at 4-time points: baseline, 1-month after surgery, and 1 and 6 months of chronic stimulation. A linear mixed model was conducted to examine the differential trajectory of rCBF changes over time. Post-hoc tests were also examined to assess postoperative, early, and late ICN changes and response-specific effects. SCC DBS had significant time-specific effects in the salience network (SN) and the default mode network (DMN). The rCBF in SN and DMN was decreased after surgery, but responder and non-responders diverged thereafter, with a net increase in DMN activity in responders with chronic stimulation. Additionally, the rCBF in the DMN uniquely correlated with depression severity. The glucose metabolic changes in a second cohort show the same DMN changes. The trajectory of PET changes with SCC DBS is not linear, consistent with the chronology of therapeutic effects. These data provide novel evidence of both an acute reset and ongoing plastic effects in the DMN that may provide future biomarkers to track clinical improvement with ongoing treatment.

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.

Brain metabolic changes and clinical response to superolateral medial forebrain bundle deep brain stimulation for treatment-resistant depression

Deep brain stimulation (DBS) to the superolateral branch of the medial forebrain bundle is an efficacious therapy for treatment-resistant depression, providing rapid antidepressant effects. In this study, we use ¹⁸F-fluorodeoxyglucose-positron emission tomography (PET) to identify brain metabolic changes over 12 months post-DBS implantation in ten of our patients, compared to baseline. The primary outcome measure was a 50% reduction in Montgomery-Åsberg Depression Rating Scale (MADRS) score, which was interpreted as a response. Deterministic fiber tracking was used to individually map the target area; probabilistic tractography was used to identify modulated fiber tracts modeled using the cathodal contacts. Eight of the ten patients included in this study were responders. PET imaging revealed significant decreases in bilateral caudate, mediodorsal thalamus, and dorsal anterior cingulate cortex metabolism that was evident at 6 months and continued to 12 months post surgery. At 12 months post-surgery, significant left ventral prefrontal cortical metabolic decreases were also observed. Right caudate metabolic decrease at 12 months was significantly correlated with mean MADRS reduction. Probabilistic tractography modeling revealed that such metabolic changes lay along cortico-limbic nodes structurally connected to the DBS target site. Such observed metabolic changes following DBS correlated with clinical response provide insights into how future studies can elaborate such data to create biomarkers to predict response, the development of which likely will require multimodal imaging analysis.

Neurobiological effects of deep brain stimulation: A systematic review of molecular brain imaging studies

Deep brain stimulation (DBS) is an established treatment for several brain disorders, including Parkinson's disease, essential tremor, dystonia and epilepsy, and an emerging therapeutic tool in many other neurological and psychiatric disorders. The therapeutic efficacy of DBS is dependent on the stimulation target, but its mechanisms of action are still relatively poorly understood. Investigating these mechanisms is challenging, partly because the stimulation devices and electrodes have limited the use of functional MRI in these patients. Molecular brain imaging techniques, such as positron emission tomography (PET) and single photon emission tomography (SPET), offer a unique opportunity to characterize the whole brain effects of DBS. Here, we investigated the direct effects of DBS by systematically reviewing studies performing an `on' vs `off' contrast during PET or SPET imaging. We identified 62 studies (56 PET and 6 SPET studies; 531 subjects). Approximately half of the studies focused on cerebral blood flow or glucose metabolism in patients Parkinson's disease undergoing subthalamic DBS (25 studies, n = 289), therefore Activation Likelihood Estimation analysis was performed on these studies. Across disorders and stimulation targets, DBS was associated with a robust local increase in ligand uptake at the stimulation site and target-specific remote network effects. Subthalamic nucleus stimulation in Parkinson's disease showed a specific pattern of changes in the motor circuit, including increased ligand uptake in the basal ganglia, and decreased ligand uptake in the primary motor cortex, supplementary motor area and cerebellum. However, there was only a handful of studies investigating other brain disorder and stimulation site combinations (1-3 studies each), or specific neurotransmitter systems, preventing definitive conclusions of the detailed molecular effects of the stimulation in these cases.

Connectomic Deep Brain Stimulation for Obsessive-Compulsive Disorder

Obsessive-compulsive disorder is among the most disabling psychiatric disorders. Although deep brain stimulation is considered an effective treatment, its use in clinical practice is not fully established. This is, at least in part, due to ambiguity about the best suited target and insufficient knowledge about underlying mechanisms. Recent advances suggest that changes in broader brain networks are responsible for improvement of obsessions and compulsions, rather than local impact at the stimulation site. These findings were fueled by innovative methodological approaches using brain connectivity analyses in combination with neuromodulatory interventions. Such a connectomic approach for neuromodulation constitutes an integrative account that aims to characterize optimal target networks. In this critical review, we integrate findings from connectomic studies and deep brain stimulation interventions to characterize a neural network presumably effective in reducing obsessions and compulsions. To this end, we scrutinize methodologies and seemingly conflicting findings with the aim to merge observations to identify common and diverse pathways for treating obsessive-compulsive disorder. Ultimately, we propose a unified network that-when modulated by means of cortical or subcortical interventions-alleviates obsessive-compulsive symptoms.

Deep brain stimulation for psychiatric disorders: role of imaging in identifying/confirming DBS targets, predicting, and optimizing outcome and unravelling mechanisms of action

Following the established application of deep brain stimulation (DBS) in the treatment of movement disorders, new non-neurological indications have emerged, such as for obsessive-compulsive disorders, major depressive disorder, dementia, Gilles de la Tourette Syndrome, anorexia nervosa, and addictions. As DBS is a network modulation surgical treatment, the development of DBS for both neurological and psychiatric disorders has been partly driven by advances in neuroimaging, which has helped explain the brain networks implicated. Advances in magnetic resonance imaging connectivity and electrophysiology have led to the development of the concept of modulating widely distributed, complex brain networks. Moreover, the increasing number of targets for treating psychiatric disorders have indicated that there may be a convergence of the effect of stimulating different targets for the same disorder, and the effect of stimulating the same target for different disorders. The aim of this paper is to review the imaging studies of DBS for psychiatric disorders. Imaging, and particularly connectivity analysis, offers exceptional opportunities to better understand and even predict the clinical outcomes of DBS, especially where there is a lack of objective biomarkers that are essential to properly guide DBS pre- and post-operatively. In future, imaging might also prove useful to individualize DBS treatment. Finally, one of the most important aspects of imaging in DBS is that it allows us to better understand the brain through observing the changes of the functional connectome under neuromodulation, which may in turn help explain the mechanisms of action of DBS that remain elusive.

Regional glucose metabolic decreases with ageing are associated with microstructural white matter changes: a simultaneous PET/MR study

PURPOSE

Human ageing is associated with a regional reduction in cerebral neuronal activity as assessed by numerous studies on brain glucose metabolism and perfusion, grey matter (GM) density and white matter (WM) integrity. As glucose metabolism may impact energetics to maintain myelin integrity, but changes in functional connectivity may also alter regional metabolism, we conducted a cross-sectional simultaneous FDG PET/MR study in a large cohort of healthy volunteers with a wide age range, to directly assess the underlying associations between reduced glucose metabolism, GM atrophy and decreased WM integrity in a single ageing cohort.

METHODS

In 94 healthy subjects between 19.9 and 82.5 years (mean 50.1 ± 17.1; 47 M/47F, MMSE ≥ 28), simultaneous FDG-PET, structural MR and diffusion tensor imaging (DTI) were performed. Voxel-wise associations between age and grey matter (GM) density, RBV partial-volume corrected (PVC) glucose metabolism, white matter (WM) fractional anisotropy (FA) and mean diffusivity (MD), and age were assessed. Clusters representing changes in glucose metabolism correlating significantly with ageing were used as seed regions for tractography. Both linear and quadratic ageing models were investigated.

RESULTS

An expected age-related reduction in GM density was observed bilaterally in the frontal, lateral and medial temporal cortex, striatum and cerebellum. After PVC, relative FDG uptake was negatively correlated with age in the inferior and midfrontal, cingulate and parietal cortex and subcortical regions, bilaterally. FA decreased with age throughout the entire brain WM. Four white matter tracts were identified connecting brain regions with declining glucose metabolism with age. Within these, relative FDG uptake in both origin and target clusters correlated positively with FA (0.32 ≤ r ≤ 0.71) and negatively with MD (- 0.75 ≤ r ≤  - 0.41).

CONCLUSION

After appropriate PVC, we demonstrated that regional cerebral glucose metabolic declines with age and that these changes are related to microstructural changes in the interconnecting WM tracts. The temporal course and potential causality between ageing effects on glucose metabolism and WM integrity should be further investigated in longitudinal cohort PET/MR studies.

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

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

Defining functional brain networks underlying obsessive-compulsive disorder (OCD) using treatment-induced neuroimaging changes: a systematic review of the literature

Approximately 2%-3% of the population suffers from obsessive-compulsive disorder (OCD). Several brain regions have been implicated in the pathophysiology of OCD, but their various contributions remain unclear. We examined changes in structural and functional neuroimaging before and after a variety of therapeutic interventions as an index into identifying the underlying networks involved. We identified 64 studies from 1990 to 2020 comparing pretreatment and post-treatment imaging of patients with OCD, including metabolic and perfusion, neurochemical, structural, functional and connectivity-based modalities. Treatment class included pharmacotherapy, cognitive-behavioural therapy/exposure and response prevention, stereotactic lesions, deep brain stimulation and transcranial magnetic stimulation. Changes in several brain regions are consistent and correspond with treatment response despite the heterogeneity in treatments and neuroimaging modalities. Most notable are decreases in metabolism and perfusion of the caudate, anterior cingulate cortex, thalamus and regions of prefrontal cortex (PFC) including the orbitofrontal cortex (OFC), dorsolateral PFC (DLPFC), ventromedial PFC (VMPFC) and ventrolateral PFC (VLPFC). Modulating activity within regions of the cortico-striato-thalamo-cortical system may be a common therapeutic mechanism across treatments. We identify future needs and current knowledge gaps that can be mitigated by implementing integrative methods. Future studies should incorporate a systematic, analytical approach to testing objective correlates of treatment response to better understand neurophysiological mechanisms of dysfunction.

Effects of short-term cognitive-coping therapy on resting-state brain function in obsessive-compulsive disorder

BACKGROUND

Obsessive-compulsive disorder (OCD) tends to be treatment refractory. Recently, cognitive-coping therapy (CCT) for OCD is reported to be an efficacious psychotherapy. However, the underlying neurophysiological mechanism remains unknown. Here, the effects of CCT on OCD and the resting-state brain function were investigated.

METHODS

Fifty-nine OCD patients underwent CCT, pharmacotherapy plus CCT (pCCT), or pharmacotherapy. Before and after a 4-week treatment, Yale-Brown obsessive-compulsive scale (Y-BOCS) was evaluated and resting-state functional magnetic resonance imaging (rs-fMRI) was scanned.

RESULTS

Compared with the baseline, significant reduction of Y-BOCS scores was found after four-week treatment (p < .001) in groups of CCT and pCCT, not in pharmacotherapy. Post-treatment Y-BOCS scores of CCT group and pCCT group were not different, but significantly lower than that of pharmacotherapy group (p < .001). Compared with pretreatment, two clusters of brain regions with significant change in amplitude of low-frequency fluctuation (ALFF) were obtained in those who treated with CCT and pCCT, but not in those who received pharmacotherapy. The ALFF in cluster 1 (insula, putamen, and postcentral gyrus in left cerebrum) was decreased, while the ALFF in cluster 2 (occipital medial gyrus, occipital inferior gyrus, and lingual gyrus in right hemisphere) was increased after treatment (corrected p < .05). The changes of ALFF were correlated with the reduction of Y-BOCS score and were greater in remission than in nonremission. The reduction of the fear of negative events was correlated to the changes of ALFF of clusters and the reduction of Y-BOCS score.

CONCLUSIONS

The effectiveness of CCT for OCD was related to the alteration of resting-state brain function-the brain plasticity.

TRIAL REGISTRATION

ChiCTR-IPC-15005969.

Neuroimaging evaluation of deep brain stimulation in the treatment of representative neurodegenerative and neuropsychiatric disorders

Brain stimulation technology has become a viable modality of reversible interventions in the effective treatment of many neurological and psychiatric disorders. It is aimed to restore brain dysfunction by the targeted delivery of specific electronic signal within or outside the brain to modulate neural activity on local and circuit levels. Development of therapeutic approaches with brain stimulation goes in tandem with the use of neuroimaging methodology in every step of the way. Indeed, multimodality neuroimaging tools have played important roles in target identification, neurosurgical planning, placement of stimulators and post-operative confirmation. They have also been indispensable in pre-treatment screen to identify potential responders and in post-treatment to assess the modulation of brain circuitry in relation to clinical outcome measures. Studies in patients to date have elucidated novel neurobiological mechanisms underlying the neuropathogenesis, action of stimulations, brain responses and therapeutic efficacy. In this article, we review some applications of deep brain stimulation for the treatment of several diseases in the field of neurology and psychiatry. We highlight how the synergistic combination of brain stimulation and neuroimaging technology is posed to accelerate the development of symptomatic therapies and bring revolutionary advances in the domain of bioelectronic medicine.

New Directions for Surgical Ablation Treatment of Obsessive Compulsive Disorder

Although there are effective treatments available for many, probably most, patients with OCD, a significant number do not respond, or fail to experience a sustained beneficial response. For patients with such chronic, disabling and 'treatment-refractory' OCD, neurosurgical treatments may be considered. The best-established neurosurgical treatments are so-called ablative procedures, where targeted lesions are created with the intention of interrupting and modifying specific circuitry functions. There is a lengthy history of such procedures and a substantial literature although this is largely of an observational nature. However, both stereotactic radiosurgery (gamma knife) and MR-guided high intensity focused ultrasound are methods of lesion generation that lend themselves to the conduct of blinded randomised trial designs and these are beginning to be utilised. In this chapter, we present a narrative review of the key recent literature that describes the evidence for the safety and efficacy of lesion procedures for OCD. For context, we also consider the strength and quality of evidence relating to intensive residential treatment for OCD (sometimes proposed as an alternative to neurosurgery), furthermore, we also present some comparative data for lesion surgery and deep brain stimulation (DBS).

Invasive and Non-invasive Neurostimulation for OCD

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

c-Fos expression following context conditioning and deep brain stimulation in the bed nucleus of the stria terminalis in rats

Deep brain stimulation (DBS) in the bed nucleus of the stria terminalis (BST), a region implicated in the expression of anxiety, shows promise in psychiatric patients, but its effects throughout the limbic system are largely unknown. In male Wistar rats, we first evaluated the neural signature of contextual fear (N = 16) and next, of the anxiolytic effects of high-frequency electrical stimulation in the BST (N = 31), by means of c-Fos protein expression. In non-operated animals, we found that the left medial anterior BST displayed increased c-Fos expression in anxious (i.e., context-conditioned) versus control subjects. Moreover, control rats showed asymmetric expression in the basolateral amygdala (BLA) (i.e., higher intensities in the right hemisphere), which was absent in anxious animals. The predominant finding in rats receiving bilateral BST stimulation was a striking increase in c-Fos expression throughout much of the left hemisphere, which was not confined to the predefined regions of interest. To conclude, we found evidence for lateralized c-Fos expression during the expression of contextual fear and anxiolytic high-frequency electrical stimulation of the BST, particularly in the medial anterior BST and BLA. In addition, we observed an extensive and unexpected left-sided c-Fos spread following bilateral stimulation in the BST.

Tractography-Guided Deep Brain Stimulation of the Anteromedial Globus Pallidus Internus for Refractory Obsessive-Compulsive Disorder: Case Report

BACKGROUND AND IMPORTANCE

Obsessive-compulsive disorder (OCD) is a disabling psychiatric disorder, mainly treated with psychotherapy and pharmacotherapy. Surgical intervention may be appropriate for patients with treatment-refractory OCD. Deep brain stimulation (DBS) is an alternative for previously common ablative surgical procedures. Tractography has been proposed as a method for individualizing DBS treatment and may have the potential to improve efficacy.

CLINICAL PRESENTATION

We present a patient with treatment-refractory OCD previously treated with bilateral leucotomies, who underwent DBS surgery with targeting informed by tractography. Preoperative tractography to identify suitable DBS targets was undertaken. Structural images were also utilized for standard stereotactic surgical planning. The anteromedial globus pallidus internus (amGPi) was chosen as the target bilaterally after consideration of white matter projections to frontal cortical regions and neurosurgical approach. Bilateral amGPi DBS surgery was undertaken without adverse events. At 16-mo follow-up, there was a 48.5% reduction in OCD symptom severity as measured by the Yale-Brown Obsessive Compulsive Scale.

CONCLUSION

The amGPi can be a successful DBS target for OCD. This is the first known case to report on DBS surgery postleucotomies for OCD and highlights the utility of tractography for surgical planning in OCD.

Predicting response to psychiatric surgery: a systematic review of neuroimaging findings

BACKGROUND

Psychiatric surgery, including deep brain stimulation and stereotactic ablation, is an important treatment option in severe refractory psychiatric illness. Several large trials have demonstrated response rates of approximately 50%, underscoring the need to identify and select responders preoperatively. Recent advances in neuroimaging have brought this possibility into focus. We systematically reviewed the psychiatric surgery neuroimaging literature to assess the current state of evidence for preoperative imaging predictors of response.

METHODS

We performed this study in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) frameworks, and preregistered it using PROSPERO. We systematically searched the Medline, Embase and Cochrane databases for studies reporting preoperative neuroimaging analyses correlated with clinical outcomes in patients who underwent psychiatric surgery. We recorded and synthesized the methodological details, imaging results and clinical correlations from these studies.

RESULTS

After removing duplicates, the search yielded 8388 unique articles, of which 7 met the inclusion criteria. The included articles were published between 2001 and 2018 and reported on the outcomes of 101 unique patients. Of the 6 studies that reported significant findings, all identified clusters of hypermetabolism, hyperconnectivity or increased size in the frontostriatal limbic circuitry.

LIMITATIONS

The included studies were few and highly varied, spanning 2 decades.

CONCLUSION

Although few studies have analyzed preoperative imaging for predictors of response to psychiatric surgery, we found consistency among the reported results: most studies implicated overactivity in the frontostriatal limbic network as being correlated with clinical response. Larger prospective studies are needed.

REGISTRATION

www.crd.york.ac.uk/prospero/display_record.php?RecordID=131151.

Anterior capsulotomy for obsessive-compulsive disorder: a review of old and new literature

Over the last two decades, deep brain stimulation (DBS) has gained popularity as a treatment of severe and medically refractory obsessive-compulsive disorder (OCD), often using brain targets informed by historical lesional neurosurgical procedures. Paradoxically, the use of DBS in OCD has led some multidisciplinary teams to revisit the use of lesional procedures, especially anterior capsulotomy (AC), although significant aversion still exists toward the use of lesional neurosurgery for psychiatric disorders. This paper aims to review all literature on the use of AC for OCD to examine its effectiveness and safety profile.All publications on AC for OCD were searched. In total 512 patients were identified in 25 publications spanning 1961-2018. In papers where a Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score was available, 73% of patients had a clinical response (i.e., > 35% improvement in Y-BOCS score) and 24% patients went into remission (Y-BOCS score < 8). In the older publications, published when the Y-BOCS was not yet available, 90% of patients were deemed to have had a significant clinical response and 39% of patients were considered symptom free. The rate of serious complications was low.In summary, AC is a safe, well-tolerated, and efficacious therapy. Its underuse is likely a result of historical prejudice rather than lack of clinical effectiveness.

Metabolic activity in subcallosal cingulate predicts response to deep brain stimulation for depression

Subcallosal cingulate (SCC) deep brain stimulation (DBS) is a promising therapy for treatment-resistant depression (TRD), but response rates in open-label studies were not replicated in a large multicenter trial. Identifying biomarkers of response could improve patient selection and outcomes. We examined SCC metabolic activity as both a predictor and marker of SCC DBS treatment response. Brain glucose metabolism (CMRGlu) was measured with [18F] FDG-PET at baseline and 6 months post DBS in 20 TRD patients in a double-blind randomized controlled trial where two stimulation types (long pulse width (LPW) n = 9 and short pulse width (SPW) n = 11) were used. Responders (n = 10) were defined by a ≥48% reduction in Hamilton Depression Rating Scale scores after 6 months. The response rates were similar with five responders in each stimulation group: LPW (55.6%) and SPW (44.5%). First, differences in SCC CMRGlu in responders and non-responders were compared at baseline. Then machine learning analysis was performed with a leave-one-out cross-validation using a Gaussian naive Bayes classifier to test whether baseline CMRGlu in SCC could categorize responders. Finally, we compared 6-month change in metabolic activity with change in depression severity. All analyses were controlled for age. Baseline SCC CMRGlu was significantly higher in responders than non-responders. The machine learning analysis predicted response with 80% accuracy. Furthermore, reduction in SCC CMRGlu 6 months post DBS correlated with symptom improvement (r(17) = 0.509; p = 0.031). This is the first evidence of an image-based treatment selection biomarker that predicts SCC DBS response. Future studies could utilize SCC metabolic activity for prospective patient selection.

Magnetic resonance-guided focused ultrasound capsulotomy for refractory obsessive compulsive disorder and major depressive disorder: clinical and imaging results from two phase I trials

Obsessive compulsive disorder (OCD) and major depressive disorder (MDD) are common, often refractory, neuropsychiatric conditions for which new treatment approaches are urgently needed. Magnetic resonance-guided focused ultrasound (MRgFUS) is a novel surgical technique permitting incisionless ablative neurosurgery. We examined the safety profile, clinical response, and imaging correlates of MRgFUS bilateral anterior capsulotomy in patients with refractory obsessive compulsive disorder (OCD, N = 6) and major depressive disorder (MDD, n = 6). There were no serious adverse events. Nonserious adverse events included headaches and pin-site swelling in 7/12 patients. The response rate was 4/6 and 2/6 in the OCD and MDD cohorts respectively. To delineate the white-matter tracts impacted by capsulotomy, a normative diffusion MRI-based structural connectome was used, revealing tracts terminating primarily in the frontal pole, medial thalamus, striatum, and medial-temporal lobe. Positron emission tomography (PET) analysis (nine subjects) revealed widespread decreases in metabolism bilaterally in the cerebral hemispheres at 6 months post treatment, as well as in the right hippocampus, amygdala, and putamen. A pretreatment seed-to-voxel resting-state functional magnetic resonance imaging (rs-fMRI) analysis (12 subjects) revealed three voxel clusters significantly associated with eventual clinical response. MRgFUS capsulotomy appears to be safe, well tolerated, and according to these initial results, may be an important treatment option for patients with refractory OCD and MDD. MRgFUS capsulotomy results in both targeted and widespread changes in neural activity, and neuroimaging may hold potential for the prediction of outcome.

A brief demonstration of frontostriatal connectivity in OCD patients with intracranial electrodes

Closed-loop neuromodulation is presumed to be the logical evolution for improving the effectiveness of deep brain stimulation (DBS) treatment protocols (Widge et al., 2018). Identifying symptom-relevant biomarkers that provide meaningful feedback to stimulator devices is an important initial step in this direction. This report demonstrates a technique for assaying neural circuitry hypothesized to contribute to OCD and DBS treatment outcomes. We computed phase-lag connectivity between LFPs and EEGs in thirteen treatment-refractory OCD patients. Simultaneous recordings from scalp EEG and externalized DBS electrodes in the ventral capsule/ventral striatum (VC/VS) were collected at rest during the perioperative treatment stage. Connectivity strength between midfrontal EEG sensors and VC/VS electrodes correlated with baseline OCD symptoms and 12-month posttreatment OCD symptoms. Results are qualified by a relatively small sample size, and limitations regarding the conclusiveness of VS and mPFC as neural generators given some concerns about volume conduction. Nonetheless, findings are consistent with treatment-relevant tractography findings and theories that link frontostriatal hyperconnectivity to the etiopathogenesis of OCD. Findings support the continued investigation of connectivity-based assays for aiding in determination of optimal stimulation location, and are an initial step towards the identification of biomarkers that can guide closed-loop neuromodulation systems.

Neuroanatomical Substrates and Predictors of Response to Capsulotomy in Intractable Obsessive-Compulsive Disorder

BACKGROUND

Anterior capsulotomy that surgically targets fiber tracts connecting prefrontal cortex and subcortical nuclei is a therapeutic option for a subgroup of patients with treatment-refractory obsessive-compulsive disorder. The goal of this study was to investigate neural correlates to anterior capsulotomy and find predictors of clinical improvement following this procedure.

METHODS

Structural and diffusion imaging data and clinical evaluation were acquired from 31 patients with refractory obsessive-compulsive disorder who underwent anterior capsulotomy. Of the 31 patients, 16 were clinical responders defined by a ≥35% reduction in the Yale-Brown Obsessive Compulsive Scale scores. Analysis of variance was applied on 2 levels (surgery and response) to examine alterations of gray matter volume and fiber tract integrity (measured by generalized fractional anisotropy). The correlation between preoperative data and clinical response was further investigated.

RESULTS

After surgery, generalized fractional anisotropy was significantly decreased in the bilateral anterior limb of the internal capsule and anterior thalamic radiation, accompanied by a decrease in gray matter volume in the prefrontal cortex, anterior cingulate cortex, striatum, thalamus, and cerebellum. Moreover, atrophy of the right caudate was greater in responders than in nonresponders, which correlated with alteration in Yale-Brown Obsessive Compulsive Scale score. In addition, preoperative gray matter volume in the right inferior frontal gyrus and generalized fractional anisotropy in the left superior longitudinal fasciculus and right cingulum predicted improved response. More anterior location of the lesion area predicted better clinical response.

CONCLUSIONS

These results demonstrate that reduced volume of the right caudate might be associated with therapeutic response of capsulotomy and might offer a potential predictor of treatment outcome and a guide for lesion site.

Local and Global Changes in Brain Metabolism during Deep Brain Stimulation for Obsessive-Compulsive Disorder

Recent approaches have suggested that deep brain stimulation (DBS) for obsessive-compulsive disorder relies on distributed networks rather than local brain modulation. However, there is insufficient data on how DBS affects brain metabolism both locally and globally. We enrolled three patients with treatment-refractory obsessive-compulsive disorder with ongoing DBS of the bilateral ventral capsule/ventral striatum. Patients underwent resting-state ¹⁸F-fluorodeoxyglucose and positron emission tomography in both stimulation ON and OFF conditions. All subjects showed relative hypometabolism in prefronto-basal ganglia-thalamic networks compared to a healthy control cohort when stimulation was switched OFF. Switching the stimulation ON resulted in differential changes in brain metabolism. Locally, volumes of activated tissue at stimulation sites (n = 6) showed a significant increase in metabolism during DBS ON compared to DBS OFF (Mean difference 4.5% ± SD 2.8; p = 0.012). Globally, differential changes were observed across patients encompassing prefrontal increase in metabolism in ON vs. OFF condition. Bearing in mind limitations of the small sample size, we conclude that DBS of the ventral capsule/ventral striatum for obsessive-compulsive disorder increases brain metabolism locally. Across distributed global networks, DBS appears to exert differential effects, possibly depending on localization of stimulation sites and response to the intervention.

Error Processing and Inhibitory Control in Obsessive-Compulsive Disorder: A Meta-analysis Using Statistical Parametric Maps

BACKGROUND

Error processing and inhibitory control enable the adjustment of behaviors to meet task demands. Functional magnetic resonance imaging studies report brain activation abnormalities in patients with obsessive-compulsive disorder (OCD) during both processes. However, conclusions are limited by inconsistencies in the literature and small sample sizes. Therefore, the aim here was to perform a meta-analysis of the existing literature using unthresholded statistical maps from previous studies.

METHODS

A voxelwise seed-based d mapping meta-analysis was performed using t-maps from studies comparing patients with OCD and healthy control subjects (HCs) during error processing and inhibitory control. For the error processing analysis, 239 patients with OCD (120 male; 79 medicated) and 229 HCs (129 male) were included, while the inhibitory control analysis included 245 patients with OCD (120 male; 91 medicated) and 239 HCs (135 male).

RESULTS

Patients with OCD, relative to HCs, showed longer inhibitory control reaction time (standardized mean difference = 0.20, p = .03, 95% confidence interval = 0.016, 0.393) and more inhibitory control errors (standardized mean difference = 0.22, p = .02, 95% confidence interval = 0.039, 0.399). In the brain, patients showed hyperactivation in the bilateral dorsal anterior cingulate cortex, supplementary motor area, and pre-supplementary motor area as well as right anterior insula/frontal operculum and anterior lateral prefrontal cortex during error processing but showed hypoactivation during inhibitory control in the rostral and ventral anterior cingulate cortices and bilateral thalamus/caudate, as well as the right anterior insula/frontal operculum, supramarginal gyrus, and medial orbitofrontal cortex (all seed-based d mapping z value >2, p < .001).

CONCLUSIONS

A hyperactive error processing mechanism in conjunction with impairments in implementing inhibitory control may underlie deficits in stopping unwanted compulsive behaviors in the disorder.

Cognitive control networks in OCD: A resting-state connectivity study in unmedicated patients with obsessive-compulsive disorder and their unaffected relatives

OBJECTIVES

Executive network deficits are putative neurocognitive endophenotypes for obsessive-compulsive disorder (OCD). Yet, unlike alterations in fronto-striatal and limbic connectivity, connectivity in the fronto-parietal (FPN) and cingulo-opercular (CON) networks involved in cognitive control has received little attention.

METHODS

The coherence of FPN, CON and fronto-limbic networks was investigated in 39 unmedicated OCD patients, 16 of their unaffected siblings and 36 healthy controls using resting-state functional-connectivity MRI and a seed-based analysis approach.

RESULTS

FPN and CON connectivity was similar for patients and controls. Siblings showed higher connectivity than patients within the CON, and between the CON and FPN compared to patients and controls (trend level). In OCD patients, but not in siblings, fronto-limbic hyperconnectivity was present compared to controls. In contrast to our expectations, no group differences in resting-state connectivity of the cognitive control networks were observed between OCD patients and controls.

CONCLUSIONS

The increased within- and between-network connectivity in siblings, but not in patients, could indicate a mechanism of increased cognitive control that may act as a protective mechanism. None of the observed network alterations can be considered an endophenotype for OCD since differences were present in either patients or siblings, but not in both groups.

Deep Brain Stimulation of Frontal Lobe Networks to Treat Alzheimer's Disease

The study objective was to evaluate the safety and efficacy of deep brain stimulation (DBS) at the ventral capsule/ventral striatum (VC/VS) region to specifically modulate frontal lobe behavioral and cognitive networks as a novel treatment approach for Alzheimer's disease (AD) patients. This is a non-randomized phase I prospective open label interventional trial of three subjects with matched comparison groups. AD participants given DBS for at least 18 months at the VC/VS target were compared on the Clinical Dementia Rating-Sum of Boxes (CDR-SB), our primary outcome clinical measure, to matched groups without DBS from the AD Neuroimaging Initiative (ADNI) cohort. Serial 2-Deoxy-2-[18F]fluoro-D-glucose (FDG) positron emission tomography (PET) images of AD participants were also compared longitudinally over time. Three AD DBS participants were matched to subjects from the ADNI cohort. All participants tolerated DBS well without significant adverse events. All three AD DBS participants had less performance decline and two of them meaningfully less decline over time on our primary outcome measure, CDR-SB, relative to matched comparison groups from the ADNI using score trajectory slopes. Minimal changes or increased metabolism on FDG-PET were seen in frontal cortical regions after chronic DBS at the VC/VS target. The first use of DBS in AD at a frontal lobe behavior regulation target (VC/VS) was well-tolerated and revealed less performance decline in CDR-SB. Frontal network modulation to improve executive and behavioral deficits should be furthered studied in AD.

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.

A study of novel bilateral thermal capsulotomy with focused ultrasound for treatment-refractory obsessive-compulsive disorder: 2-year follow-up

BACKGROUND

Recently, a new thermal lesioning approach using magnetic-resonance-guided focused ultrasound (MRgFUS) was introduced for the treatment of neurologic disorders. However, only 2 studies have used this approach for treatment-refractory obsessive-compulsive disorder (OCD), and follow-up was short-term. We investigated the efficacy and safety of bilateral thermal lesioning of the anterior limb of the internal capsule using MRgFUS in patients with treatment-refractory OCD and followed them for 2 years.

METHODS

Eleven patients with treatment-refractory OCD were included in the study. Clinical outcomes were evaluated using the Yale-Brown Obsessive Compulsive Scale, the Clinical Global Impression scale (including improvement and severity), the Hamilton Rating Scale for Depression (HAM-D) and the Hamilton Rating Scale for Anxiety (HAM-A) at 1 week and 1, 3, 6, 12 and 24 months following MRgFUS. Neuropsychological functioning, Global Assessment of Functioning and adverse events were also assessed.

RESULTS

After MRgFUS, Yale-Brown Obsessive Compulsive Scale scores decreased significantly across the 24-month follow-up period (mean ± standard deviation, 34.4 ± 2.3 at baseline v. 21.3 ± 6.2 at 24 months, p < 0.001). Scores on the Hamilton rating scales for depression and anxiety also significantly decreased from baseline to 24 months (HAM-D, 19.0 ± 5.3 v. 7.6 ± 5.3, p < 0.001; HAM-A, 22.4 ± 5.9 v. 7.9 ± 3.9, p < 0.001). Global Assessment of Functioning scores improved significantly (35.8 ± 4.9 at baseline v. 56.0 ± 10.3 at 24 months, p < 0.001) and Memory Quotient significantly improved, but other neuropsychological functions were unchanged. The side effects of MRgFUS included headache and vestibular symptoms, but these were mild and transient.

LIMITATIONS

The main limitations of this study were the small sample size and the open-label design.

CONCLUSION

Bilateral thermal lesioning of the anterior limb of the internal capsule using MRgFUS may improve obsessive-compulsive, depressive and anxiety symptoms in patients with treatment-refractory OCD, without serious adverse effects.

Brain and Behavior: Commentary on Two Cases Involving the Effect of Structural Brain Lesions on Psychiatric Disorders

In this issue of the journal, 2 case reports are presented that illustrate explicit influences of structural brain lesions on psychiatric symptoms. In both cases, the patients had preexisting, classically diagnosed psychiatric disorders-schizophrenia in the first case and bipolar I disorder in the second case. In the first case, a 61-year-old woman with chronic paranoid schizophrenia experienced a marked reduction in psychotic symptoms after bilateral frontal strokes. In the second case, a 60-year-old man who had experienced manic and depressive episodes since his 20s developed partial complex seizures after having repeated head trauma in his 40s, with subsequent onset of chronic personality changes associated with temporal lobe epilepsy that made his psychiatric treatment a greater challenge. The presentations in these 2 cases raise intriguing neuropsychiatric questions concerning the effects on regional brain activity of a variety of nonpharmacological psychiatric interventions (eg, stereotactic neurosurgical techniques, deep brain stimulation, electroconvulsive therapy, certain types of psychotherapy), and concerning possible physiological pathways shared by seizure kindling in epilepsy and recurrent episodes of bipolar disorder.

Nuclear medicine of the cerebellum

Single-photon emission computed tomography (SPECT) and positron emission tomography (PET) with different radiotracers enable regional evaluation of blood flow and glucose metabolism, of receptors and transporters of several molecules, and of abnormal deposition of peptides and proteins in the brain. The cerebellum has been used as a reference region for different radiotracers in several disease conditions. Whole-brain voxel-wise analysis is not affected by a priori knowledge bias and should be preferred. SPECT and PET have contributed to establishing the cerebellum role in motion, cognition, and emotion control in physiologic and pathophysiologic conditions. The basic abnormal imaging findings include decreased or increased uptake of flow or metabolism tracers in the cerebellum alone or as part of a network. Decreased uptake is generally observed in primary structural damage of the cerebellum, but can also represent a distant effect of cerebral damage (crossed diaschisis). Increased uptake can be observed in Freidreich ataxia, inflammatory or immune-mediated diseases of the cerebellum, and in status epilepticus. The possibility is also recognized that primary structural damage of the cerebellum might determine distance effects on other brain structures (reversed diaschisis). So far, SPECT and PET have been predominantly used in clinical studies to investigate cerebellar changes in neurologic and psychiatric diseases and in connection with pharmacologic, transcranial magnetic stimulation, deep-brain stimulation, or surgical treatments.

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

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

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

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

Mechanisms of deep brain stimulation

Deep brain stimulation (DBS) is widely used for the treatment of movement disorders including Parkinson's disease, essential tremor, and dystonia and, to a lesser extent, certain treatment-resistant neuropsychiatric disorders including obsessive-compulsive disorder. Rather than a single unifying mechanism, DBS likely acts via several, nonexclusive mechanisms including local and network-wide electrical and neurochemical effects of stimulation, modulation of oscillatory activity, synaptic plasticity, and, potentially, neuroprotection and neurogenesis. These different mechanisms vary in importance depending on the condition being treated and the target being stimulated. Here we review each of these in turn and illustrate how an understanding of these mechanisms is inspiring next-generation approaches to DBS.

Deep Brain Stimulation for Obsessive Compulsive Disorder Reduces Symptoms of Irritable Bowel Syndrome in a Single Patient

Irritable bowel syndrome (IBS) is a frequent gastrointestinal disorder that is difficult to treat. We describe findings from evaluation of a woman (55 years old) with obsessive compulsive disorder, which was treated with bilateral deep brain stimulation in the anterior limb of the internal capsule, and IBS. After the brain stimulation treatment she reported substantial relief of her IBS symptoms. This reduction depended on specific stimulation parameters, was reproducible over time, and was not directly associated with improvements in obsessive compulsive disorder symptoms. These observations indicate a specific effect of deep brain stimulation on IBS. This observation confirms involvement of specific brain structures in the pathophysiology of IBS and shows that symptoms can be reduced through modulation of neuronal activity in the central nervous system. Further studies of the effects of brain stimulation on IBS are required.

Ablative Limbic System Surgery: Review and Future Directions

The limbic system is a network of interconnected brain regions regulating emotion, memory, and behavior. Pathology of the limbic system can manifest as psychiatric disease, including obsessive-compulsive disorder and major depressive disorder. For patients with these disorders who have not responded to standard pharmacological and cognitive behavioral therapy, ablative surgery is a neurosurgical treatment option. The major ablative limbic system procedures currently used are anterior capsulotomy, dorsal anterior cingulotomy, subcaudate tractotomy, and limbic leucotomy. In this review, we include a brief history of ablative limbic system surgery leading up to its current form. Mechanistic justification for these procedures is considered in a discussion of the pathophysiology of psychiatric disease. We then discuss therapeutic efficacy as demonstrated by recent trials. Finally, we consider future directions, including the search for predictors of treatment response, the development of more precise targeting methods, and the use of advances in neuroimaging to track treatment response.

Subcallosal Cingulate Connectivity in Anorexia Nervosa Patients Differs From Healthy Controls: A Multi-tensor Tractography Study

BACKGROUND

Anorexia nervosa is characterized by extreme low body weight and alterations in affective processing. The subcallosal cingulate regulates affect through wide-spread white matter connections and is implicated in the pathophysiology of anorexia nervosa.

OBJECTIVES

We examined whether those with treatment refractory anorexia nervosa undergoing deep brain stimulation (DBS) of the subcallosal white matter (SCC) show: (1) altered anatomical SCC connectivity compared to healthy controls, (2) white matter microstructural changes, and (3) microstructural changes associated with clinically-measured affect.

METHODS

Diffusion magnetic resonance imaging (dMRI) and deterministic multi-tensor tractography were used to compare anatomical connectivity and microstructure in SCC-associated white matter tracts. Eight women with treatment-refractory anorexia nervosa were compared to 8 age- and sex-matched healthy controls. Anorexia nervosa patients also completed affect-related clinical assessments presurgically and 12 months post-surgery.

RESULTS

(1) Higher (e.g., left parieto-occipital cortices) and lower (e.g., thalamus) connectivity in those with anorexia nervosa compared to controls. (2) Decreases in fractional anisotropy, and alterations in axial and radial diffusivities, in the left fornix crus, anterior limb of the internal capsule (ALIC), right anterior cingulum and left inferior fronto-occipital fasciculus. (3) Correlations between dMRI metrics and clinical assessments, such as low pre-surgical left fornix and right ALIC fractional anisotropy being related to post-DBS improvements in quality-of-life and depressive symptoms, respectively.

CONCLUSIONS

We identified widely-distributed differences in SCC connectivity in anorexia nervosa patients consistent with heterogenous clinical disruptions, although these results should be considered with caution given the low number of subjects. Future studies should further explore the use of affect-related connectivity and behavioral assessments to assist with DBS target selection and treatment outcome.

Transcranial direct current stimulation in obsessive-compulsive disorder: emerging clinical evidence and considerations for optimal montage of electrodes

BACKGROUND

Neuromodulation techniques for obsessive-compulsive disorder (OCD) treatment have expanded with greater understanding of the brain circuits involved. Transcranial direct current stimulation (tDCS) might be a potential new treatment for OCD, although the optimal montage is unclear.

OBJECTIVE

To perform a systematic review on meta-analyses of repetitive transcranianal magnetic stimulation (rTMS) and deep brain stimulation (DBS) trials for OCD, aiming to identify brain stimulation targets for future tDCS trials and to support the empirical evidence with computer head modeling analysis.

METHODS

Systematic reviews of rTMS and DBS trials on OCD in Pubmed/MEDLINE were searched. For the tDCS computational analysis, we employed head models with the goal of optimally targeting current delivery to structures of interest.

RESULTS

Only three references matched our eligibility criteria. We simulated four different electrodes montages and analyzed current direction and intensity.

CONCLUSION

Although DBS, rTMS and tDCS are not directly comparable and our theoretical model, based on DBS and rTMS targets, needs empirical validation, we found that the tDCS montage with the cathode over the pre-supplementary motor area and extra-cephalic anode seems to activate most of the areas related to OCD.

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

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