Long-Term Safety and Efficacy of Focused Ultrasound Capsulotomy for Obsessive-Compulsive Disorder and Major Depressive Disorder

BACKGROUND

Magnetic resonance-guided focused ultrasound (MRgFUS) trials targeting the anterior limb of the internal capsule have shown promising results. We evaluated the long-term safety and efficacy of MRgFUS capsulotomy in patients with obsessive-compulsive disorder (OCD) and major depressive disorder (MDD).

METHODS

This phase 1, single-center, open-label study recruited patients with treatment-resistant OCD and MDD. Outcomes were measured 6 months, 12 months, and 18 to 24 months (long term) after MRgFUS capsulotomy. Neuropsychological testing and neuroimaging were conducted at baseline and 12 months postoperatively. The primary outcome was safety. The secondary outcome was clinical response, defined for OCD as a ≥35% improvement in Yale-Brown Obsessive Compulsive Scale scores and for MDD as a ≥50% reduction in Hamilton Depression Rating Scale scores compared with baseline.

RESULTS

No serious adverse effects were registered. In patients with OCD (n= 15), baseline Yale-Brown Obsessive Compulsive Scale scores (31.9 ± 1.2) were significantly reduced by 23% (p = .01) at 6 months and 35% (p < .0001) at 12 months. In patients with MDD (n = 12), a 26% and 25% nonsignificant reduction in Hamilton Depression Rating Scale scores (baseline 24.3 ± 1.2) was observed at 6 months and 12 months, respectively. Neuropsychological testing revealed no negative effects of capsulotomy. In the OCD and MDD cohorts, we found a correlation between clinical outcome and lesion laterality, with more medial left-placed lesions (OCD, p = .08) and more lateral right-placed lesions (MDD, p < .05) being respectively associated with a stronger response. In the MDD cohort, more ventral tracts appeared to be associated with a poorer response.

CONCLUSIONS

MRgFUS capsulotomy is safe in patients with OCD and MDD and particularly effective in the former population.

Ventral capsule/ventral striatum deep brain stimulation versus anterior capsulotomy in treatment-resistant major depression: A systematic review and data analysis

BACKGROUND

Ventral capsule/ventral striatum deep brain stimulation (VC/VS-DBS) for treatment-resistant depression (TRD) has shown promising results. Despite its efficacy, DBS is costly and less accessible, while anterior capsulotomy (ACAPS), though permanent and non-adjustable, offers clinical advantages.

METHODS

A systematic review and data analysis were conducted to evaluate articles reporting on clinical outcomes and adverse effects of VC/VS-DBS and ACAPS for TRD. A quality assessment of the included studies was performed to determine homogeneity across reports. To assess the intervention's efficacy, changes in pre- and post-intervention scores on the Hamilton Depression Rating Scale (HRSD-17) were analyzed.

RESULTS

Seven studies with 138 TRD patients were analyzed. Among 75 ACAPS patients, mean pre-operative HRSD-17 scores decreased by 46 %, from 26.97 ± 3.12-14.53 ± 1.15, with an improvement of 11.87 points (95 % CI: 8.83-14.91). For 63 VC/VS-DBS patients, scores declined by 42 %, from 27.5 ± 4.13-15.93 ± 5.13, corresponding to an improvement of 9.68 points (95 % CI: 5.08-14.27). Adverse effects included suicidal ideation (7 %) and hypomania (3.6 %) with DBS, while ACAPS was associated with headaches and long-term effects like reduced motivation and weight gain in 15-20 % of patients.

CONCLUSION

Both VC/VS-DBS and ACAPS show efficacy in treating TRD, with ACAPS showing slightly better outcomes and no significant adverse effects reported. However, given study heterogeneity, a robust, well-powered randomized controlled trial is essential to more precisely compare these techniques and clarify their clinical impact on TRD.

Comparative Side-Effects of Neurosurgical Treatment of Treatment-Resistant Depression

INTRODUCTION

Treatment-resistant depression (TRD) is a condition in which patients suffering from depression no longer respond to common methods of treatment, such as anti-depressant medication. Neurosurgical procedures such as ablative surgery, deep brain stimulation, and vagus nerve stimulation have been used in efforts to overcome TRD.

OBJECTIVES

This review aims to provide an overview of the side effects of neurosurgery performed in clinical studies related to depression.

METHODS

A literature search was conducted through PubMed, MEDLINE, EMBASE, Ovid, and ClinicalTrials.gov databases.

RESULTS

This review selected 10 studies for ablative surgery, 12 for deep brain stimulation, and 10 for vagus nerve stimulation, analyzing their side effect profiles of neurosurgery for TRD. The major side effects of each type of neurosurgery were identified, such as incontinence and confusion for ablative surgery, headaches and increased suicide ideation for deep brain stimulation, and voice hoarseness and dyspnea for vagus nerve stimulation.

CONCLUSION

The review discusses the merits and demerits of neurosurgery as a treatment option for TRD. It also suggests new insights into decreasing the burden of these neurosurgical side effects so that they can be a viable, high-efficacy treatment method for TRD.

Bilateral Anterior Capsulotomy for Treatment-Resistant Obsessive-Compulsive Disorder

INTRODUCTION

Ablative surgery is an intervention of last resort for treatment-resistant obsessive-compulsive disorder (TROCD). Our center has been using bilateral anterior capsulotomy (BAC) for the past 20 years for patients eligible for limbic surgery. This report details our experience with BAC for TROCD.

METHOD

Five patients with OCD met eligibility criteria for BAC. Entry protocols were complex and took around 6 months to complete. Stereotactic radiofrequency was used to produce the capsulotomies. Lesion length varied between 5.7 and 16.9 mm in the coronal plane. Patients were followed between 4 and 20 years.

RESULTS

All 5 patients (100%) were responders as defined by the widely accepted criteria of a reduction of ≥35% in Yale-Brown Obsessive Compulsive Scale (YBOCS) score at 18-month follow-up. Four patients remained responders at the 48 months. One patient was lost to follow-up. Responder status when viewed from the perspective of the YBOCS was sustained over the 4- to 20-year follow-up with one relapse 19 years postsurgery when medications were discontinued. Real-world psychiatric outcomes were different as other vulnerabilities surfaced illustrating the multifactorial determinants of mental health. No patient had any significant long-term neurocognitive or physical side effects.

CONCLUSION

BAC should remain an option of last resort for patients with severe OCD who remain unresponsive to all other interventions.

Ventral targeted anterior capsulotomy for treatment-resistant depression and obsessive-compulsive disorder: A treatment method with cases

BACKGROUND

Ablative surgery using bilateral anterior capsulotomy (BAC) is an option for treatment resistant depression (TRD) and obsessive-compulsive disorder (TROCD). The location and extent of the lesion within anterior limb of the internal capsule (ALIC) remains uncertain. Accumulating evidence has suggested that the lesion should be located ventrally while limiting the dorsal extent. Our center is now targeting specific fiber tracts within the lower half of the ALIC.

METHOD

Presurgical diffusion tensor Magnetic Resonance Imaging (MRI) was used to identify individual fibre tracts within the ventral aspect of the ALIC in the last two patients who underwent BAC at our center. One patient had TRD and the other had both TROCD and TRD. Radiofrequency-induced thermal lesions were created in the identified targets with lesion volumes between 20 and 229 mm3 (average 95 mm3).

FINDINGS

Both patients were responders with neither experiencing significant side effects including compromised executive functions.

LIMITATIONS

The generalizability of our findings is limited because the outcome is based on two subjects.

CONCLUSION

This work suggests that BAC can be individually tailored and more limited to the ventral aspect of the ALIC and is effective and safe for TRD and TROCD. Accumulating data also suggests that to be clinically effective the length of the capsulotomy should be about 10mm. BAC's use may increase with the growing utilization and mastery of magnetic resonance guided focused ultrasound.

Kinematic Effects of Combined Subthalamic and Dorsolateral Nigral Deep Brain Stimulation in Parkinson's Disease

Background

Additional stimulation of the substantia nigra (SNr) has been proposed to target axial symptoms and gait impairment in patients with Parkinson's disease (PD).

Objective

This study aimed to characterize effects of combined deep brain stimulation (DBS) of the subthalamic nucleus (STN) and SNr on gait performance in PD and to map stimulation sites within the SNr.

Methods

In a double-blinded crossover design, 10 patients with PD and gait impairment underwent clinical examination and kinematic assessment with STN DBS, combined STN+SNr DBS and OFF DBS 30 minutes after reprogramming. To confirm stimulation within the SNr, electrodes, active contacts, and stimulation volumes were modeled in a common space and overlap with atlases of SNr was computed.

Results

Overlap of stimulation volumes with dorsolateral SNr was confirmed for all patients. UPDRS III, scoring of freezing during turning and transitioning, stride length, stride velocity, and range of motion of shank, knee, arm, and trunk as well as peak velocities during turning and transitions and turn duration were improved with STN DBS compared to OFF. On cohort level, no further improvement was observed with combined STN+SNr DBS but additive improvement of spatiotemporal gait parameters was observed in individual subjects.

Conclusions

Combined high frequency DBS of the STN and dorsolateral SNr did not consistently result in additional short-term kinematic or clinical benefit compared to STN DBS. Stimulation intervals, frequency, and patient selection for target symptoms as well as target region within the SNr need further refinement in future trials.

Repetitive Negative Thinking-Specific and -Nonspecific White Matter Tracts Engaged by Historical Psychosurgical Targets for Depression

BACKGROUND

Repetitive negative thinking (RNT) is a frequent symptom of major depressive disorder (MDD) that is associated with poor outcomes and treatment resistance. While most studies on RNT have focused on structural and functional characteristics of gray matter, this study aimed to examine the association between white matter (WM) tracts and interindividual variability in RNT.

METHODS

A probabilistic tractography approach was used to characterize differences in the size and anatomical trajectory of WM fibers traversing psychosurgery targets historically useful in the treatment of MDD (anterior capsulotomy, anterior cingulotomy, and subcaudate tractotomy) in patients with MDD and low (n = 53) or high (n = 52) RNT, and healthy control subjects (n = 54). MDD samples were propensity matched on depression and anxiety severity and demographics.

RESULTS

WM tracts traversing left hemisphere targets and reaching the ventral anterior body of the corpus callosum (thus extending to contralateral regions) were larger in the high-RNT MDD group compared with low-RNT (effect size D = 0.27, p = .042) and healthy control (D = 0.23, p = .02) groups. MDD was associated with greater size of tracts that converge onto the right medial orbitofrontal cortex regardless of RNT intensity. Other RNT-nonspecific findings in MDD involved tracts reaching the left primary motor and right primary somatosensory cortices.

CONCLUSIONS

This study provides the first evidence to our knowledge that WM connectivity patterns, which could become targets of intervention, differ between high- and low-RNT participants with MDD. These WM differences extend to circuits that are not specific to RNT, possibly subserving reward mechanisms and psychomotor activity.

Validation of Lead-DBS β-Oscillation Localization with Directional Electrodes

In deep brain stimulation (DBS) studies in patients with Parkinson's disease, the Lead-DBS toolbox allows the reconstruction of the location of β-oscillations in the subthalamic nucleus (STN) using Vercise Cartesia directional electrodes (Boston Scientific). The objective was to compare these probabilistic locations with those of intraoperative monopolar β-oscillations computed from local field potentials (0.5-3 kHz) recorded by using shielded single wires and an extracranial shielded reference electrode. For each electrode contact, power spectral densities of the β-band (13-31 Hz) were compared with those of all eight electrode contacts on the directional electrodes. The DBS Intrinsic Template AtLas (DISTAL), electrophysiological, and DBS target atlases of the Lead-DBS toolbox were applied to the reconstructed electrodes from preoperative MRI and postoperative CT. Thirty-six electrodes (20 patients: 7 females, 13 males; both STN electrodes for 16 of 20 patients; one single STN electrode for 4 of 20 patients) were analyzed. Stimulation sites both dorsal and/or lateral to the sensorimotor STN were the most efficient. In 33 out of 36 electrodes, at least one contact was measured with stronger β-oscillations, including 23 electrodes running through or touching the ventral subpart of the β-oscillations' probabilistic volume, while 10 did not touch it but were adjacent to this volume; in 3 out of 36 electrodes, no contact was found with β-oscillations and all 3 were distant from this volume. Monopolar local field potentials confirmed the ventral subpart of the probabilistic β-oscillations.

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.

Lead-DBS v3.0: Mapping deep brain stimulation effects to local anatomy and global networks

Following its introduction in 2014 and with support of a broad international community, the open-source toolbox Lead-DBS has evolved into a comprehensive neuroimaging platform dedicated to localizing, reconstructing, and visualizing electrodes implanted in the human brain, in the context of deep brain stimulation (DBS) and epilepsy monitoring. Expanding clinical indications for DBS, increasing availability of related research tools, and a growing community of clinician-scientist researchers, however, have led to an ongoing need to maintain, update, and standardize the codebase of Lead-DBS. Major development efforts of the platform in recent years have now yielded an end-to-end solution for DBS-based neuroimaging analysis allowing comprehensive image preprocessing, lead localization, stimulation volume modeling, and statistical analysis within a single tool. The aim of the present manuscript is to introduce fundamental additions to the Lead-DBS pipeline including a deformation warpfield editor and novel algorithms for electrode localization. Furthermore, we introduce a total of three comprehensive tools to map DBS effects to local, tract- and brain network-levels. These updates are demonstrated using a single patient example (for subject-level analysis), as well as a retrospective cohort of 51 Parkinson's disease patients who underwent DBS of the subthalamic nucleus (for group-level analysis). Their applicability is further demonstrated by comparing the various methodological choices and the amount of explained variance in clinical outcomes across analysis streams. Finally, based on an increasing need to standardize folder and file naming specifications across research groups in neuroscience, we introduce the brain imaging data structure (BIDS) derivative standard for Lead-DBS. Thus, this multi-institutional collaborative effort represents an important stage in the evolution of a comprehensive, open-source pipeline for DBS imaging and connectomics.

Connectivity-based parcellation of the amygdala and identification of its main white matter connections

The amygdala plays a role in emotion, learning, and memory and has been implicated in behavioral disorders. Better understanding of the amygdala circuitry is crucial to develop new therapies for these disorders. We used data from 200 healthy-subjects from the human connectome project. Using probabilistic tractography, we created population statistical maps of amygdala connectivity to brain regions involved in limbic, associative, memory, and reward circuits. Based on the amygdala connectivity with these regions, we applied k-means clustering to parcellate the amygdala into three clusters. The resultant clusters were averaged across all subjects and the main white-matter pathways of the amygdala from each averaged cluster were generated. Amygdala parcellation into three clusters showed a medial-to-lateral pattern. The medial cluster corresponded with the centromedial and cortical nuclei, the basal cluster with the basal nuclei and the lateral cluster with the lateral nuclei. The connectivity analysis revealed different white-matter pathways consistent with the anatomy of the amygdala circuit. This in vivo connectivity-based parcellation of the amygdala delineates three clusters of the amygdala in a mediolateral pattern based on its connectivity with brain areas involved in cognition, memory, emotion, and reward. The human amygdala circuit presented in this work provides the first step for personalized amygdala circuit mapping for patients with behavioral disorders.

Stereotactic cingulotomy and capsulotomy for obsessive-compulsive disorders: Indications and comparative results

Stereotactic cingulotomy and capsulotomy have been used to treat obsessive-compulsive disorders (OCD) and treatment-resistant depression since the 1950s-60s. To date, these surgical procedures have gained a number of advancements due to progress of neuroimaging and upgrading of stereotactic technique. The effectiveness of operations is related to the restoration of the normal level of limbic regulation in treated patients. In cases of OCD, capsulotomy is somewhat more effective, while cingulotomy has a more favorable safety profile. Moreover, clinical experience shows that these procedures may be efficient for management not only OCD itself, but for obsessive-compulsive symptoms in cases of other mental diseases, such as Tourette syndrome and schizophrenia, thus may be considered in carefully selected patients. An individualized treatment strategy, including staged stereotactic interventions, seems most promising for attainment of the best possible outcomes, and may allow to achieve socialization of 75% of the operated patients with minimal pharmacological support. Other potential stereotactic targets for management of OCD, which selection may depend on detail of clinical manifestation of disease, include thalamic nuclei, nucleus accumbens, globus pallidus, the amygdala, etc., and are currently under active evaluation, and their use is tremendously facilitated by the development of deep brain stimulation techniques. Nevertheless, cingulotomy and capsulotomy still remain highly relevant for treatment of patients with therapy-resistant mental disorders.

The Evolution of Modern Ablative Surgery for the Treatment of Obsessive-Compulsive and Major Depression Disorders

In this review, we describe the evolution of modern ablative surgery for intractable psychiatric disease, from the original image-guided cingulotomy procedure described by Ballantine, to the current bilateral anterior cingulotomy using MRI-guided stereotactic techniques. Extension of the single lesion bilateral cingulotomy to the extended bilateral cingulotomy and subsequent staged limbic leucotomy (LL) is also discussed. Other ablative surgeries for psychiatric disease including subcaudate tractotomy (SCT) and anterior capsulotomy (AC) using modern MRI-guided ablative techniques, as well as radiosurgical capsulotomy, are described. Finally, the potential emerging role of MR-guided focused ultrasound (MRgFUS) for treating conditions such as major depressive disorder (MDD) and obsessive-compulsive disorder (OCD) is discussed.

Abnormal White Matter Microstructure in the Limbic System Is Associated With Tuberous Sclerosis Complex-Associated Neuropsychiatric Disorders

Objective

Tuberous sclerosis complex (TSC) is a genetic disease that arises from TSC1 or TSC2 abnormalities and induces the overactivation of the mammalian/mechanistic target of rapamycin pathways. The neurological symptoms of TSC include epilepsy and tuberous sclerosis complex-associated neuropsychiatric disorders (TAND). Although TAND affects TSC patients' quality of life, the specific region in the brain associated with TAND remains unknown. We examined the association between white matter microstructural abnormalities and TAND, using diffusion tensor imaging (DTI).

Methods

A total of 19 subjects with TSC and 24 age-matched control subjects were enrolled. Tract-based spatial statistics (TBSS) were performed to assess group differences in fractional anisotropy (FA) between the TSC and control groups. Atlas-based association analysis was performed to reveal TAND-related white matter in subjects with TSC. Multiple linear regression was performed to evaluate the association between TAND and the DTI parameters; FA and mean diffusivity in seven target regions and projection fibers.

Results

The TBSS showed significantly reduced FA in the right hemisphere and particularly in the inferior frontal occipital fasciculus (IFOF), inferior longitudinal fasciculus (ILF), superior longitudinal fasciculus (SLF), uncinate fasciculus (UF), and genu of corpus callosum (CC) in the TSC group relative to the control group. In the association analysis, intellectual disability was widely associated with all target regions. In contrast, behavioral problems and autistic features were associated with the limbic system white matter and anterior limb of the internal capsule (ALIC) and CC.

Conclusion

The disruption of white matter integrity may induce underconnectivity between cortical and subcortical regions. These findings suggest that TANDs are not the result of an abnormality in a specific brain region, but rather caused by connectivity dysfunction as a network disorder. This study indicates that abnormal white matter connectivity including the limbic system is relevant to TAND. The analysis of brain and behavior relationship is a feasible approach to reveal TAND related white matter and neural networks. TAND should be carefully assessed and treated at an early stage.

Magnetic Resonance-Guided Focused Ultrasound Capsulotomy for Treatment-Resistant Psychiatric Disorders

BACKGROUND

Psychiatric surgery is an important domain of functional neurosurgery and involves deep brain stimulation (DBS) or lesional procedures performed for treatment-resistant psychiatric illness. It has recently become possible to use magnetic-guided focused ultrasound (MRgFUS) to perform bilateral capsulotomy, a lesional technique commonly carried out with surgical radiofrequency ablation or stereotactic radiosurgery. MRgFUS offers several advantages, including improved safety and real-time imaging of the lesions.

OBJECTIVE

To describe the clinical and technical aspects of performing bilateral MRgFUS capsulotomy in patients with severe refractory depression and obsessive-compulsive disorder.

METHODS

We describe the clinical and technical considerations of performing MRgFUS capsulotomy. Topics discussed include patient selection, headframe application, targeting, sonication strategies, and follow-up procedures.

RESULTS

MRgFUS capsulotomy was performed in 16 patients without serious clinical or radiographic adverse events.

CONCLUSION

MRgFUS allows for a safe, less invasive technique for performing a well-studied psychiatric surgery procedure-the anterior capsulotomy.

Tractography-Guided Anterior Capsulotomy for Major Depression and Obsessive-Compulsive Disorder: Targeting the Emotion Network

BACKGROUND

Bilateral anterior capsulotomy (BAC) is an effective surgical option for patients with treatment-resistant major depression (TRMD) and treatment-resistant obsessive-compulsive disorder (TROCD). The size of the lesion and its precise dorsal-ventral location within the anterior limb of the internal capsule (ALIC) remain undefined.

OBJECTIVE

To present a method to identify the trajectories of the associative and limbic white matter pathways within the ALIC for targeting in BAC surgery.

METHODS

Using high-definition tractography, we prospectively tested the feasibility of this method in 2 patients with TRMD and TROCD to tailor the capsulotomy lesion to their limbic pathway.

RESULTS

The trajectories of the associative and limbic pathways were identified in the ALIC of both patients and we targeted the limbic pathways by defining the dorsal limit of the lesion in a way to minimize the damage to the associative pathways. The final lesions were smaller than those that have been previously published. This individualized procedure was associated with long-term benefit in both patients.

CONCLUSION

Tractography-guided capsulotomy is feasible and was associated with long-term benefit in patients with TRMD and TROCD.

The Frontal Aslant Tract and Supplementary Motor Area Syndrome: Moving towards a Connectomic Initiation Axis

Simple Summary

Connectomics enables us to map whole brain networks that can be applied to operative neurosurgery to improve neuro-oncological outcomes. Damage to the superior frontal gyrus during frontal lobe surgery is thought to induce supplementary motor area (SMA) syndrome in patients. However, network-based modeling may provide a more accurate cortical model of SMA syndrome, including the Frontal Aslant Tract (FAT). The aim of our study was to retrospectively assess if surgical tractography with diffusion tensor imaging (DTI) decreases the likelihood of SMA syndrome. Compared to patients who underwent surgery preserving the SFG (n = 23), patients who had their FAT and SMA networks mapped through DTI and subsequently preserved were less likely to experience transient SMA syndrome. Preserving the FAT and SMA improves functional outcomes in patients following medial frontal glioma surgery and demonstrates how network-based approaches can improve surgical outcomes.

Abstract

Connectomics is the use of big data to map the brain’s neural infrastructure; employing such technology to improve surgical planning may improve neuro-oncological outcomes. Supplementary motor area (SMA) syndrome is a well-known complication of medial frontal lobe surgery. The ‘localizationist’ view posits that damage to the posteromedial bank of the superior frontal gyrus (SFG) is the basis of SMA syndrome. However, surgical experience within the frontal lobe suggests that this is not entirely true. In a study on n = 45 patients undergoing frontal lobe glioma surgery, we sought to determine if a ‘connectomic’ or network-based approach can decrease the likelihood of SMA syndrome. The control group (n = 23) underwent surgery avoiding the posterior bank of the SFG while the treatment group (n = 22) underwent mapping of the SMA network and Frontal Aslant Tract (FAT) using network analysis and DTI tractography. Patient outcomes were assessed post operatively and in subsequent follow-ups. Fewer patients (8.3%) in the treatment group experienced transient SMA syndrome compared to the control group (47%) (p = 0.003). There was no statistically significant difference found between the occurrence of permanent SMA syndrome between control and treatment groups. We demonstrate how utilizing tractography and a network-based approach decreases the likelihood of transient SMA syndrome during medial frontal glioma surgery. We found that not transecting the FAT and the SMA system improved outcomes which may be important for functional outcomes and patient quality of life.

The Use of Tractography-Based Targeting in Deep Brain Stimulation for Psychiatric Indications

Deep Brain Stimulation (DBS) has been investigated as a treatment option for patients with refractory psychiatric illness. Over the past two decades, neuroimaging developments have helped to advance the field, particularly the use of diffusion tensor imaging (DTI) and tractographic reconstruction of white-matter pathways. In this article, we review translational considerations and how DTI and tractography have been used to improve targeting during DBS surgery for depression, obsessive compulsive disorder (OCD) and post-traumatic stress disorder (PTSD).

Examining cognitive change in magnetic resonance-guided focused ultrasound capsulotomy for psychiatric illness

Magnetic resonance-guided focused ultrasound (MRgFUS) anterior capsulotomy is a novel treatment option for patients with refractory obsessive compulsive disorder (OCD) or major depressive disorder (MDD). However, there is concern that lesional psychiatric surgery procedures may have adverse effects on cognition. In this study, we examined whether MRgFUS capsulotomy causes cognitive decline in patients with psychiatric illness. Ten patients with refractory OCD (n = 5) or MDD (n = 5) underwent MRgFUS capsulotomy. Cognitive functioning was measured at baseline as well as 6 months and 12 months postoperatively, with a battery of neuropsychological tests assessing domains of executive function, memory, and processing speed. Scores were analyzed at the individual-level, and changes ≥2 standard deviations were considered clinically significant. We also examined whether changes in clinical symptoms were associated with changes in cognitive performance. At baseline intellectual functioning was in the average to high-average range for the group. Following MRgFUS capsulotomy, there were no deteriorations in cognition that reached ≥2 standard deviations at 6 or 12 months. Eight out of ten patients demonstrated a ≥2 standard deviation improvement in at least one cognitive score at 6 or 12 months postoperatively. Improvements in clinical symptoms correlated significantly with self-reported improvements in frontal lobe function (p < 0.05), but not with objective measures of cognitive functioning. To summarize, MRgFUS capsulotomy did not result in cognitive decline in this cohort of patients with refractory OCD or MDD, suggesting that this procedure can be offered to patients with a very low risk of cognitive side effects.

Regionconnect: Rapidly extracting standardized brain connectivity information in voxel-wise neuroimaging studies

Reporting white matter findings in voxel-wise neuroimaging studies typically lacks specificity in terms of brain connectivity. Therefore, the purpose of this work was to develop an approach for rapidly extracting standardized brain connectivity information for white matter regions with significant findings in voxel-wise neuroimaging studies. The new approach was named regionconnect and is based on precalculated average healthy adult brain connectivity information stored in standard space in a fashion that allows fast retrieval and integration. Towards this goal, the present work first generated and evaluated the white matter connectome of the IIT Human Brain Atlas v.5.0. It was demonstrated that the edges of the atlas connectome are representative of those of individual participants of the Human Connectome Project in terms of the spatial organization of streamlines and spatial patterns of track-density. Next, the new white matter connectome was used to develop multi-layer, connectivity-based labels for each white matter voxel of the atlas, consistent with the fact that each voxel may contain axons from multiple connections. The regionconnect algorithm was then developed to rapidly integrate information contained in the multi-layer labels across voxels of a white matter region and to generate a list of the most probable connections traversing that region. Usage of regionconnect does not require high angular resolution diffusion MRI or any MRI data. The regionconnect algorithm as well as the white matter tractogram and connectome, multi-layer, connectivity-based labels, and associated resources developed for the IIT Human Brain Atlas v.5.0 in this work are available at www.nitrc.org/projects/iit. An interactive, online version of regionconnect is also available at www.iit.edu/~mri.

Tract-based analysis of target engagement by subcallosal cingulate deep brain stimulation for treatment resistant depression

BACKGROUND

Deep brain stimulation (DBS) of subcallosal cingulate cortex (SCC) is a promising investigational therapy for treatment-resistant depression (TRD). However, outcomes vary, likely due to suboptimal DBS placement. Ideal placement is proposed to stimulate 4 SCC white matter bundles; however, no quantitative data have linked activation of these target tracts to response.

OBJECTIVE

Here we used the volume of tissue activated (VTA) and probabilistic diffusion tensor imaging (DTI) to quantify tract activation relating to response.

METHODS

DTI was performed in 19 TRD patients who received SCC-DBS. We defined clinical response as >48% reduction from baseline in the Hamilton Depression Rating Scale. Bilateral VTAs were generated based on subject-specific stimulation parameters. Patient-specific tract maps emanating from the VTAs were calculated using whole-brain probabilistic DTI. The four target tracts were isolated using tract-specific quantification and examined for overlap with DBS activated tissue.

RESULTS

Medial frontal and temporal projections were stimulated in all responders at 6 and 12 months. Individual tract-based generalized linear mixed model analysis revealed a significant tract-by-response interaction at both 6 (F(1,135) = 3.828, p = 0.001) and 12 (F(1,135) = 5.688, p < 0.001) months, with post hoc tests revealing a response-related increase in cingulum activation at 6 months (t(135) = 2.418, p = 0.017) and decrease in forceps minor activation at 12 months (t(135) = -2.802, p = 0.006).

CONCLUSIONS

A wider profile of white matter tracts, particularly to the medial frontal, was associated with DBS response. Cingulum bundle stimulation may promote early response and excess stimulation of the forceps minor might be detrimental. Our work supports prospective patient-specific targeting to inform personalized DBS.