Surgery for movement disorders

Artificial intelligence-enhanced intraoperative neurosurgical workflow: state of the art and future perspectives

BACKGROUND

Artificial Intelligence (AI) and Machine Learning (ML) augment decision-making processes and productivity by supporting surgeons over a range of clinical activities: from diagnosis and preoperative planning to intraoperative surgical assistance. We reviewed the literature to identify current AI platforms applied to neurosurgical perioperative and intraoperative settings and describe their role in multiple subspecialties.

METHODS

A systematic review of the literature was conducted following the PRISMA guidelines. PubMed, EMBASE, and Scopus databases were searched from inception to December 31, 2020. Original articles were included if they: presented AI platforms implemented in perioperative, intraoperative settings and reported ML models' performance metrics. Due to the heterogeneity in neurosurgical applications, a qualitative synthesis was deemed appropriate. The risk of bias and applicability of predicted outcomes were assessed using the PROBAST tool.

RESULTS

41 articles were included. All studies evaluated a supervised learning algorithm. A total of 10 ML models were described; the most frequent were neural networks (n = 15) and tree-based models (n = 13). Overall, the risk of bias was medium-high, but applicability was considered positive for all studies. Articles were grouped into 4 categories according to the subspecialty of interest: neuro-oncology, spine, functional and other. For each category, different prediction tasks were identified.

CONCLUSIONS

In this review, we summarize the state-of-art applications of AI for the intraoperative augmentation of neurosurgical workflows across multiple subspecialties. ML models may boost surgical team performances by reducing human errors and providing patient-tailored surgical plans, but further and higher-quality studies need to be conducted.

Cryptococcal Meningitis Causing Refractory Hemichorea-Hemiballismus Treated With Pallidotomy

We report a case of a 31-year-old immunocompetent male who presented with altered mental status and agitation requiring intubation. As sedation was weaned, he demonstrated choreiform movements with associated hemiballismus of the right upper and lower extremities, and he was ultimately diagnosed with cryptococcal meningitis. The patient’s chorea did not terminate after the completion of induction antifungal therapy and all pharmacologic options for the management of chorea were ineffective. He underwent a successful unilateral pallidotomy using standard stereotactic methodology targeting the posterior-ventral pallidum, and his choreiform movements dramatically improved post-operatively within 48 hours.

Focused ultrasound for functional neurosurgery

INTRODUCTION

Brain lesioning is a fundamental technique in the functional neurosurgery world. It has been investigated for decades and presented promising results long before novel pharmacological agents were introduced to treat movement disorders, psychiatric disorders, pain, and epilepsy. Ablative procedures were replaced by effective drugs during the 1950s and by Deep Brain Stimulation (DBS) in the 1990s as a reversible neuromodulation technique. In the last decade, however, the popularity of brain lesioning has increased again with the introduction of magnetic resonance-guided focused ultrasound (MRgFUS).

OBJECTIVE

In this review, we will cover the current and emerging role of MRgFUS in functional neurosurgery.

METHODS

Literature review from PubMed and compilation.

RESULTS

Investigated since 1930, MRgFUS is a technology enabling targeted energy delivery at the convergence of mechanical sound waves. Based on technological advancements in phased array ultrasound transducers, algorithms accounting for skull penetration by sound waves, and MR imaging for targeting and thermometry, MRgFUS is capable of brain lesioning with sub-millimeter precision and can be used in a variety of clinical indications.

CONCLUSION

MRgFUS is a promising technology evolving as a dominant tool in different functional neurosurgery procedures in movement disorders, psychiatric disorders, epilepsy, among others.

Does Personality Change Follow Deep Brain Stimulation in Parkinson's Disease Patients?

Deep Brain Stimulation (DBS) has emerged as a safe, effective, and appealing treatment for Parkinson's Disease (PD), particularly for improving motor symptoms (e. g., tremor, bradykinesia, and rigidity). However, concerns have been raised about whether DBS causes psychological changes, including changes to personality: characteristic and relatively stable patterns of affect, behavior, cognition, and desire. In this article, after first presenting some background information about PD and DBS, we examined evidence obtained from various empirical research methods (quantitative, qualitative, and mixed methods for evaluating patient valued characteristics) pertaining to whether DBS causes personality change. General limitations across research methods include a lack of randomized clinical trials and small sample sizes. We organized our review of findings according to different layers of personality variables: dispositional traits (including personality pathology), characteristic adaptations, and narrative identity. Though most work has been done on dispositional traits, there is not much evidence that dispositional traits change following DBS. Little work has been done on characteristic adaptations, but there is somewhat consistent evidence for positive perceived progress toward goals across a number of domains: routine activities, work, social/relational, and leisure. Nascent work on narrative identity holds promise for revealing issues around self-image that may be common following DBS. We listed a number of strategies for advancing research, highlighting opportunities related to personality conceptualization, personality assessment, and interdisciplinary scholarship. Finally, we offer practical applications of our findings for the informed consent process and for ongoing treatment.

Deep Brain Stimulation and Motor Cortex Stimulation for Chronic Pain

Deep brain stimulation (DBS) and Motor Cortex stimulation (MCS) have been used for control of chronic pain. Chronic pain of any origin is complex and difficult to treat. Stimulation of various areas in brain-like sensory thalamus, medial nuclei of thalamus including centro-lateral nucleus of thalamus (CL), periaqueductal gray, periventricular gray, nucleus accumbence and motor cortex provides partial relief in properly selected patients. This article reviews the pain pathways, theories of pain, targets for DBS and rationale of DBS and MCS. It also discusses the patient selection, technical details of each target.

Microsurgery and Neuromodulation for Facial Spasms

Facial spasms are of various types. Hemifacial spasm (HFS) is characterized by unilateral tonic-clonic contractions of facial muscles, following a specific pattern of disease progression. It has well-delineated clinical, radiological and electrophysiological features. We have conducted an extensive review of existing literature on the subject, as regards etiopathogenesis, clinical features, investigations and management options for facial spasms. Primary Hemifacial spasm (HFS) may be treated using pharmacotherapy, botulinum toxin injections or microvascular decompression surgery. Microvascular decompression has the potential to reverse the pathological changes of the disease and has proved to be the most successful of all treatment options. Other facial spasms are exceedingly difficult to treat and may need neuromodulation as an option. The following article attempts to review the clinical features and therapeutic approaches to managing patients with facial spasms.

Correlation between fractional anisotropy changes in the targeted ventral intermediate nucleus and clinical outcome after transcranial MR-guided focused ultrasound thalamotomy for essential tremor: results of a pilot study

OBJECTIVE

This study evaluated changes of fractional anisotropy (FA) in the ventral intermediate nucleus (VIM) of the thalamus after transcranial MR-guided focused ultrasound (TcMRgFUS) thalamotomy and their associations with clinical outcome.

METHODS

Clinical and radiological data of 12 patients with medically refractory essential tremor (mean age 76.5 years) who underwent TcMRgFUS thalamotomy with VIM targeting were analyzed retrospectively. The Clinical Rating Scale for Tremor (CRST) score was calculated before and at 1 year after treatment. Measurements of the relative FA (rFA) values, defined as ratio of the FA value in the targeted VIM to the FA value in the contralateral VIM, were performed before thalamotomy, and 1 day and 1 year thereafter.

RESULTS

TcMRgFUS thalamotomy was well tolerated and no long-term complications were noted. At 1-year follow-up, 8 patients demonstrated relief of tremor (improvement group), whereas in 4 others persistent tremor was noted (recurrence group). In the entire cohort, mean rFA values in the targeted VIM before treatment, and at 1 day and 1 year after treatment, were 1.12 ± 0.15, 0.44 ± 0.13, and 0.82 ± 0.22, respectively (p < 0.001). rFA values were consistently higher in the recurrence group compared with the improvement group, and the difference reached statistical significance at 1 day (p < 0.05) and 1 year (p < 0.01) after treatment. There was a statistically significant (p < 0.01) positive correlation between rFA values in the targeted VIM at 1 day after thalamotomy and CRST score at 1 year after treatment. Receiver operating characteristic curve analysis revealed that the optimal cutoff value of rFA at 1 day after thalamotomy for prediction of symptomatic improvement at 1-year follow-up is 0.54.

CONCLUSIONS

TcMRgFUS thalamotomy results in significant decrease of rFA in the targeted VIM, at both 1 day and 1 year after treatment. Relative FA values at 1 day after treatment showed significant correlation with CRST score at 1-year follow-up. Therefore, FA may be considered a possible imaging biomarker for early prediction of clinical outcome after TcMRgFUS thalamotomy for essential tremor.

Pragmatism and the Importance of Interdisciplinary Teams in Investigating Personality Changes following DBS

Gilbert and colleagues (2018) point out the discrepancy between the limited empirical data illustrating changes in personality (and related concepts of identity, agency, authenticity, autonomy, and self, i.e., PIAAAS) following implantation of deep brain stimulating (DBS) electrodes and the vast number of conceptual neuroethics papers implying that these changes are widespread, deleterious, and clinically significant. Their findings are reminiscent of C. P. Snow’s essay on the divide between the two cultures of the humanities (representing the conceptual publications) and the sciences (representing the empirical work). This division in the literature raises significant ethical concerns surrounding unjustified fear of personality changes in the context of DBS and negative perceptions of clinician-scientists engaged in DBS. These concerns have real world implications for funding future innovative, DBS trials aimed to reduce suffering as well as hampering true interdisciplinary scholarship. We argue that the philosophical tradition of pragmatism and the value it places on empirical inquiry, experiential knowledge, and inter-disciplinary scholarship – reflecting diverse ways of knowing – provides a framework to start to address the important questions Gilbert and colleagues raise. In particular, we highlight the importance of expert clinician knowledge in contributing to the neuroethical questions raised by Gilbert and colleagues. Finally, we provide illustrative examples of some of our interdisciplinary empirical research that demonstrate the iterative cycle of inquiry characteristic of pragmatism in which conceptual neuroethics questions have led to empirical studies whose results then raise additional conceptual questions that give rise to new empirical studies in a way that highlights the contributions of the humanities and the sciences.

7.0T ultrahigh-field MRI directly visualized the pedunculopontine nucleus in Parkinson's disease patients

OBJECTIVES

The pedunculopontine nucleus (PPN) is considered a promising new target for neurostimulation in Parkinson's disease (PD) patients with postural instability and gait disturbance that is refractory to other treatment modalities. However, the PPN is typically difficult to visualize with magnetic resonance imaging (MRI) at clinical field strengths, which greatly limits the PPN as a viable surgical target for deep brain stimulation (DBS). Thus, the aim of this study is to directly visualize the PPN based on 7.0T ultrahigh-field MRI.

METHODS

Five PD patients were enrolled and scanned using the MP2RAGE sequence on a 7.0T ultrahigh-field MRI scanner. Then, the MP2RAGE sequences were imported into a commercially available navigation system. The coordinates of the directly localized PPN poles were recorded in the navigation system relative to the anterior commissure-posterior commissure plane.

RESULTS

Our results indicated that the PPN presented intermediate signal intensity in the 7.0T ultrahigh-field MR images in comparison with the surrounding structure, such as the hypo-intensity of the periaqueductal gray and the hyperintensity of the neighboring white matter tracts, in PD patients. The mean coordinates for the rostral and caudal poles of PPN were 6.50 mm and 7.20 mm lateral, 1.58 mm and 2.21 mm posterior, and 8.89 mm and 13.83 mm relative to the posterior commissure.

CONCLUSION

Our findings provide, for the first time, direct visualization of the PPN using the MP2RAGE sequence on a 7.0T ultrahigh-field MRI, which may improve the accuracy of stereotactic targeting of the PPN and improve the outcomes in patients undergoing DBS.

Changes in self-perception in patients treated with neurostimulating devices

BACKGROUND

In recent years, qualitative changes in self-perception have been reported in individual patients undergoing brain stimulation to treat their neurological disease. We here report a first systematic study addressing these unwanted treatment effects in a semiquantitative way.

HYPOTHESES

Hypothesis 1 (H1): Changes in self-perception can be detected and documented in patients following interventions with various neurostimulating devices using standardized assessment tools. Hypothesis 2 (H2): Central nervous-implanted neurostimulating devices (deep brain stimulation [DBS]) will have a greater impact on the patient's self-perception than "peripheral" implanted devices (implanted vagus nerve stimulation [iVNS]) and external devices (transcutaneous vagus nerve stimulation [tVNS] or transcutaneous electrical trigeminal nerve stimulation [eTNS]).

METHODS

Application of a newly developed semiquantitative questionnaire (FST-questionnaire [Fragebogen zur Veränderung der Selbstwahrnehmung unter tiefer Hirnstimulation]: Questionnaire regarding changes in self-perception while treated with DBS) to systematically assess changes in self-perception in a single-center, cross-sectional pilot-study at the University Hospital Freiburg, Germany on 50 patients (44% male; age 50 years [range: 27-73 years]), undergoing neurostimulation (DBS, iVNS, tVNS, or eTNS) to treat Parkinson's disease or epilepsy.

RESULTS

Standardized assessment detected alterations in self-perception in all treatment groups (H1 approved). This included rare self-alienating changes in self-perception. Unexpectedly, peripheral neurostimulation had similar effects as central stimulation techniques.

CONCLUSIONS

Properly designed questionnaires - like the FST-questionnaire as standardized assessment tool - can detect changes in self-perception in patients during neurostimulatory treatment in a wide spectrum of brain stimulation techniques. This may provide a strategy to systematically identify the subgroup of patients liable to experience such problems during treatment already prior to treatment decisions.

The Role of a Neuropsychologist on a Movement Disorders Deep Brain Stimulation Team

The term movement disorders is misleading in the implication that the symptoms are limited to motor problems. Most movement disorders include a variety of neurobehavioral and neurocognitive symptoms that require neuropsychological expertise. The goal of this paper is to provide a rationale and practical roadmap for neuropsychologists' involvement in a Movement Disorders team with a specific focus on pre-operative deep brain stimulation (DBS) evaluations. Pragmatic recommendations regarding requisite skills, clinical practice, recommendations, communication, and benefits are outlined.

Surgical treatments for essential tremor

INTRODUCTION

Essential tremor is the most common form of pathologic tremor. Surgical therapies disrupt tremorogenic oscillation in the cerebellothalamocortical pathway and are capable of abolishing severe tremor that is refractory to available pharmacotherapies. Surgical methods are raspidly improving and are the subject of this review. Areas covered: A PubMed search on 18 January 2018 using the query essential tremor AND surgery produced 839 abstracts. 379 papers were selected for review of the methods, efficacy, safety and expense of stereotactic deep brain stimulation (DBS), stereotactic radiosurgery (SRS), focused ultrasound (FUS) ablation, and radiofrequency ablation of the cerebellothalamocortical pathway. Expert commentary: DBS and SRS, FUS and radiofrequency ablations are capable of reducing upper extremity tremor by more than 80% and are far more effective than any available drug. The main research questions at this time are: 1) the relative safety, efficacy, and expense of DBS, SRS, and FUS performed unilaterally and bilaterally; 2) the relative safety and efficacy of thalamic versus subthalamic targeting; 3) the relative safety and efficacy of atlas-based versus direct imaging tractography-based anatomical targeting; and 4) the need for intraoperative microelectrode recordings and macroelectrode stimulation in awake patients to identify the optimum anatomical target. Randomized controlled trials are needed.

Molecular Therapy of Melanocortin-4-Receptor Obesity by an Autoregulatory BDNF Vector

Mutations in the melanocortin-4-receptor (MC4R) comprise the most common monogenic form of severe early-onset obesity, and conventional treatments are either ineffective long-term or contraindicated. Immediately downstream of MC4R-in the pathway for regulating energy balance-is brain-derived neurotrophic factor (BDNF). Our previous studies show that adeno-associated virus (AAV)-mediated hypothalamic BDNF gene transfer alleviates obesity and diabetes in both diet-induced and genetic models. To facilitate clinical translation, we developed a built-in autoregulatory system to control therapeutic gene expression mimicking the body's natural feedback systems. This autoregulatory approach leads to a sustainable plateau of body weight after substantial weight loss is achieved. Here, we examined the efficacy and safety of autoregulatory BDNF gene therapy in Mc4r heterozygous mice, which best resemble MC4R obese patients. Mc4r heterozygous mice were treated with either autoregulatory BDNF vector or YFP control and monitored for 30 weeks. BDNF gene therapy prevented the development of obesity and metabolic syndromes characterized by decreasing body weight and adiposity, suppressing food intake, alleviating hyperleptinemia and hyperinsulinemia, improving glucose and insulin tolerance, and increasing energy expenditure, without adverse cardiovascular function or behavioral disturbances. These safety and efficacy data provide preclinical evidence that BDNF gene therapy is a compelling treatment option for MC4R-deficient obese patients.

Clinical Ethics in the Context of Deep Brain Stimulation for Movement Disorders

OBJECTIVE

Discuss common clinical ethical challenges encountered in working with patients who are candidates for deep brain stimulation (DBS) for the treatment of motor symptoms of Parkinson's disease (PD).

METHOD

The relevant literature is reviewed and supplemented by descriptive, ethically challenging cases stemming from decades of combined experience working on DBS teams. We outline ethical arguments and provide pragmatic recommendations to assist neuropsychologists working in movement disorder teams.

RESULTS

The goals of the pre-operative neuropsychological DBS assessment include: (1) identification of potential cognitive risk factors; (2) identification of relevant neuropsychiatric or neurobehavioral factors; (3) assessment of level of family support; and (4) systematic assessment of patient's and family member's goals or expectations for DBS. The information gleaned from the pre-operative neuropsychological assessment is highly relevant to the most commonly studied clinical ethics challenges encountered in DBS: (1) assessment of risk/benefit; (2) determinations regarding inclusion/exclusion; (3) autonomy; and (4) patient's perception of benefit and quality of life.

CONCLUSIONS

Neuropsychologists are particularly well poised to provide unique and important insights to assist with developing the most ethically sound practices that take into account patient's values as well as fiduciary responsibilities to the patient, the team, the profession, and the broader community.

MRI-Guided Focused Ultrasound in Parkinson's Disease: A Review

MRI-guided focused ultrasound is a new technology that enables intracranial ablation. Since lesioning ameliorates some of the symptoms of PD, this technology is being explored as a possible treatment for medication resistant symptoms in PD patients. The purpose of this paper is to review the clinical use and treatment outcomes of PD patients treated to date with this technology.

Stereotactic Laser Ablation for Medically Intractable Epilepsy: The Next Generation of Minimally Invasive Epilepsy Surgery

Epilepsy is a common, disabling illness that is refractory to medical treatment in approximately one-third of patients, particularly among those with mesial temporal lobe epilepsy. While standard open mesial temporal resection is effective, achieving seizure freedom in most patients, efforts to develop safer, minimally invasive techniques have been underway for over half a century. Stereotactic ablative techniques, in particular, radiofrequency (RF) ablation, were first developed in the 1960s, with refinements in the 1990s with the advent of modern computed tomography and magnetic resonance-based imaging. In the past 5 years, the most recent techniques have used MRI-guided laser interstitial thermotherapy (LITT), the development of which began in the 1980s, saw refinements in MRI thermal imaging through the 1990s, and was initially used primarily for the treatment of intracranial and extracranial tumors. The present review describes the original stereotactic ablation trials, followed by modern imaging-guided RF ablation series for mesial temporal lobe epilepsy. The developments of LITT and MRI thermometry are then discussed. Finally, the two currently available MRI-guided LITT systems are reviewed for their role in the treatment of mesial temporal lobe and other medically refractory epilepsies.

Interventional magnetic resonance imaging-guided subthalamic nucleus deep brain stimulation for Parkinson's disease: Patient selection

BACKGROUND

Interventional magnetic resonance imaging (iMRI) guided deep brain stimulation (DBS) for Parkinson's disease (PD) has been shown to be effective. The costs of a dedicated intraoperative MRI may be prohibitive. The procedure can also be performed in a diagnostic scanner, however this presents challenges for utilization of time when the scanner is used both as a diagnostic and an interventional unit. This report outlines our novel methodology for patient selection for implantation in a diagnostic MR scanner, as an attempt to streamline the use of resources. A retrospective review of our outcomes is also presented.

METHODS

DBS candidacy evaluation included a PD questionnaire-39. Anxiety, age, difficulties in communication and body habitus were factors that were assessed in selecting patients for this technique. Eleven patients underwent iMRI-guided DBS implantation in the subthalamic nucleus. All patients were implanted bilaterally. Unified PD rating scale (UPDRS) part III and L-dopa dose were compared pre- and post-stimulation. A cohort of 11 DBS patients not selected for iMRI-guided DBS were also reported for comparison.

RESULTS

For the iMRI-guided patients, mean "Off" UPDRS III score was 47.6 (standard deviation [SD] 8.26). Postoperative "On" medication, "On" stimulation UPDRS III was 13.6 (SD 5.23). Mean preoperative L-dopa dose was 1060 mg (SD 474.3) and mean postoperative L-dopa dose was 320 (SD 298.3).

CONCLUSION

iMRI-guided DBS is a newly emerging technique for surgical treatment of patients with PD. We present a novel scoring system for patient selection assessing anxiety, age, ability to communicate, and body habitus to identify patients who will be benefited most from this technique.

Deep brain stimulation complicated by bilateral large cystic cavitation around the leads in a patient with Parkinson's disease

Deep brain stimulation (DBS) is an approved and effective therapy for patients suffering from advanced Parkinson's disease (PD). Several clinical trials have indicated significant motor function improvement in patients undergoing subthalamic nucleus stimulation. This therapy is, rarely, associated with complications, mostly related to infections, seizures or stimulation-induced side effects. We report a case of a 71-year-old man with a 10-year history of PD who underwent bilateral placement of subthalamic nucleus DBS. As a complication, the patient showed subjective postoperative cognitive decline, and subsequent MRI showed peri-lead oedema, which progressed to large cystic cavitation around the leads without indication of infection. The patient received steroid therapy and the cavitations regressed without surgical intervention.

Disease-modifying therapeutic directions for Lewy-Body dementias

Dementia with Lewy bodies (DLB) is the second leading cause of dementia following Alzheimer's disease (AD) and accounts for up to 25% of all dementia. DLB is distinct from AD in that it involves extensive neuropsychiatric symptoms as well as motor symptoms, leads to enormous societal costs in terms of direct medical care and is associated with high financial and caregiver costs. Although, there are no disease-modifying therapies for DLB, we review several new therapeutic directions in treating DLB. We discuss progress in strategies to decrease the level of alpha-synuclein, to prevent the cell to cell transmission of misfolded alpha-synuclein, and the potential of brain stimulation in DLB.

Practical considerations and nuances in anesthesia for patients undergoing deep brain stimulation implantation surgery

The field of functional neurosurgery has expanded in last decade to include newer indications, new devices, and new methods. This advancement has challenged anesthesia providers to adapt to these new requirements. This review aims to discuss the nuances and practical issues that are faced while administering anesthesia for deep brain stimulation surgery.

Deep brain stimulation in Huntington's disease: assessment of potential targets

Huntington's disease (HD) is an autosomal-dominant neurodegenerative disorder that has very few effective therapeutic interventions. Since the disease has a defined neural circuitry abnormality, neuromodulation could be an option. Case reports, original research, and animal model studies were selected from the databases of Medline and PubMed. All related studies published up to July 2014 were included in this review. The following search terms were used: "Deep brain stimulation," "DBS," "thalamotomy," "pallidal stimulation," and "Huntington's Disease," "HD," "chorea," or "hyperkinetic movement disorders." This review examines potential nodes in the HD circuitry that could be modulated using deep brain stimulation (DBS) therapy. With rapid evolution of imaging and ability to reach difficult targets in the brain with refined DBS technology, some phenotypes of HD could potentially be treated with DBS in the near future. Further clinical studies are warranted to validate the efficacy of neuromodulation and to determine the most optimal target for HD.

Successful subthalamic nucleus deep brain stimulation therapy after significant lead displacement from a subdural hematoma

A 57-year-old man with a 21 year history of Parkinson's disease underwent bilateral subthalamic nucleus deep brain stimulation (DBS) placement. One week postoperatively he developed an acute left subdural hematoma from a fall with significant displacement of the DBS leads. It was promptly evacuated, the patient slowly recovered neurologically, and the leads again moved near to the original position. Six months of stimulation therapy attained 50% reduction in symptoms. This case report demonstrates the movement of DBS leads due to brain shift and their ability to come back to previous location once the brain shift is corrected.

A groove technique for securing an electrode connector on the cranial bone: case analysis of efficacy

Objective

A groove technique for securing an electrode connector was described as an alternative surgical technique in deep brain stimulation (DBS) surgery to avoid electrode connector-related complications, such as skin erosion, infection, and migration.

Methods

We retrospectively reviewed 109 patients undergoing one of two techniques; the standard technique (52 patients using 104 electrodes) and the groove technique (57 patients using 109 electrodes) for securing the electrode connector in DBS surgery, regardless of patient disease. In the standard percutaneous tunneling technique, the connector was placed on the vertex of the cranial surface. The other technique, so called the groove technique, created a groove (about 4 cm long, 8 mm wide) in the cranial bone at the posterior parietal area. Wound erosion and migration related to the connectors were compared between the two techniques.

Results

The mean follow-up period was 73 months for the standard method and 46 months for the groove technique. Connector-related complications were observed in three patients with the groove technique and in seven patients with the standard technique. Wound erosion at the connector sites per electrode was one (0.9%) with the groove technique and six (5.8%) with the standard technique. This difference was statistically significant. The electrode connector was migrated in two patients with the groove technique and in one patient with the standard technique.

Conclusions

The groove technique, which involves securing an electrode using a groove in the cranial bone at the posterior parietal area, offers an effective and safe method to avoid electrode connector-related complications during DBS surgery.

[The use of neuromodulation for the treatment of tremor]

BACKGROUND

Tremor may be a disabling disorder and pharmacologic treatment is the first-line therapy for these patients. Nevertheless, this treatment may lead to a satisfactory tremor reduction in only 50% of patients with essential tremor. Thalamotomy was the treatment of choice for tremor refractory to medical therapy until deep brain stimulation (DBS) of the ventral intermedius nucleus (Vim) of the thalamus has started being used. Nowadays, thalamotomy is rarely performed.

METHODS

This article is a non-systematic review of the indications, results, programming parameters and surgical technique of DBS of the Vim for the treatment of tremor.

RESULTS

In spite of the fact that it is possible to achieve similar clinical results using thalamotomy or DBS of the Vim, the former causes more adverse effects than the latter. Furthermore, DBS can be used bilaterally, whereas thalamotomy has a high risk of causing disartria when it is performed in both sides. DBS of the Vim achieved an adequate tremor improvement in several series of patients with tremor caused by essential tremor, Parkinson's disease or multiple sclerosis. Besides the Vim, there are other targets, which are being used by some authors, such as the zona incerta and the prelemniscal radiations.

CONCLUSION

DBS of the Vim is a useful treatment for disabling tremor refractory to medical therapy. It is essential to carry out an accurate patient selection as well as to use a proper surgical technique. The best stereotactic target for tremor is still unknown, although the Vim is the most used one.

[Surgery for behavioral disorders: the state of the art]

BACKGROUND

Surgery for behavioral disorders (SBD) is becoming a more common treatment since the development of neuromodulation techniques.

METHODS

This article is a non-systematic review of the history, current indications, techniques and surgical targets of SBD. We divide its history into 3 eras: the first era starts in the beginning of psychosurgery and finishes with the development of stereotactic techniques, when the second one starts. It is characterized by the realization of stereotactic lesions. We are traveling through the third era, which begins when deep brain stimulation (DBS) starts to be used for SBD.

RESULTS

In spite of the serious mistakes committed in the past, nowadays, SBD is reawakening. The psychiatric disorders which are most frequently treated by surgery are: treatment-resistant depression, obsessive-compulsive disorder and Tourette syndrome. Furthermore, some patients with abnormal aggression were surgically treated. There are several stereotactic targets described for these disorders. Vagus nerve stimulation may be also used for depression.

CONCLUSION

The results of DBS in these disorders seem to be encouraging. However, more randomized trials are needed in order to establish the effectiveness of SBD. It must be taken in mind that a proper patient selection will help us to perform a safer procedure as well as to achieve better surgical results, leading SBD to be more accepted by psychiatrists, patients and their families. Further research is needed in several topics such as: physiopathology of behavioral disorders, indications of SBD and new surgical targets.

Factors predicting incremental administration of antihypertensive boluses during deep brain stimulator placement for Parkinson's disease

Hypertension is common in deep brain stimulator (DBS) placement predisposing to intracranial hemorrhage. This retrospective review evaluates factors predicting incremental antihypertensive use intraoperatively. Medical records of Parkinson's disease (PD) patients undergoing DBS procedure between 2008-2011 were reviewed after Institutional Review Board approval. Anesthesia medication, preoperative levodopa dose, age, preoperative use of antihypertensive medications, diabetes mellitus, anxiety, motor part of the Unified Parkinson's Disease Rating Scale score and PD duration were collected. Univariate and multivariate analysis was done between each patient characteristic and the number of antihypertensive boluses. From the 136 patients included 60 were hypertensive, of whom 32 were on angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB), told to hold on the morning of surgery. Antihypertensive medications were given to 130 patients intraoperatively. Age (relative risk [RR] 1.01; 95% confidence interval [CI] 1.00-1.02; p=0.005), high Joint National Committee (JNC) class (p<0.0001), diabetes mellitus (RR 1.4; 95%CI 1.2-17; p<0.0001) and duration of PD >10 years (RR 1.2; 95%CI 1.1-1.3; p=0.001) were independent predictors for antihypertensive use. No difference was noted in the mean dose of levodopa (p=0.1) and levodopa equivalent dose (p=0.4) between the low (I/II) and high severity (III/IV) JNC groups. Addition of dexmedetomidine to propofol did not influence antihypertensive boluses required (p=0.38). Intraoperative hypertension during DBS surgery is associated with higher age group, hypertensive, diabetic patients and longer duration of PD. Withholding ACEI or ARB is an independent predictor of hypertension requiring more aggressive therapy. Levodopa withdrawal and choice of anesthetic agent is not associated with higher intraoperative antihypertensive medications.

Activation of the central nervous system induced by micro-magnetic stimulation

Electrical and transcranial magnetic stimulations have proven to be therapeutically beneficial for patients suffering from neurological disorders. Moreover, these stimulation technologies have provided invaluable tools for investigating nervous system functions. Despite this success, these technologies have technical and practical limitations impeding the maximization of their full clinical and preclinical potential. Recently, micro-magnetic stimulation, which may offer advantages over electrical and transcranial magnetic stimulation, has proven effective in activating the neuronal circuitry of the retina in vitro. Here we demonstrate that this technology is also capable of activating neuronal circuitry on a systems level using an in vivo preparation. Specifically, the application of micro-magnetic fields to the dorsal cochlear nucleus activates inferior colliculus neurons. Additionally, we demonstrate the efficacy and characteristics of activation using different magnetic stimulation parameters. These findings provide a rationale for further exploration of micro-magnetic stimulation as a prospective tool for clinical and preclinical applications.

Successful deep brain stimulation surgery with intraoperative magnetic resonance imaging on a difficult neuroacanthocytosis case: case report

BACKGROUND AND IMPORTANCE

Chorea acanthocytosis is a progressive hereditary neurodegenerative disorder characterized by hyperkinetic movements, seizures, and acanthocytosis in the absence of any lipid abnormality. Medical treatment is typically limited and disappointing.

CLINICAL PRESENTATION

We report on a 32-year-old patient with chorea acanthocytosis with a failed attempt at awake deep brain stimulation (DBS) surgery due to intraoperative seizures and postoperative intracranial hematoma. He then underwent a second DBS operation, but under general anesthesia and with intraoperative magnetic resonance imaging guidance. Marked improvement in his dystonia, chorea, and overall quality of life was noted 2 and 8 months postoperatively.

CONCLUSION

DBS surgery of the bilateral globus pallidus pars interna may be useful in controlling the hyperkinetic movements in neuroacanthocytosis. Because of the high propensity for seizures in this disorder, DBS performed under general anesthesia, with intraoperative magnetic resonance imaging guidance, may allow successful implantation while maintaining accurate target localization.

Posttraumatic stress disorder: neurocircuitry and implications for potential deep brain stimulation

Posttraumatic stress disorder (PTSD) is a prevalent and highly disabling psychiatric disorder that is notoriously difficult to treat. At some point in their lifetimes, 5-8% of men, 10-14% of women, and up to a quarter of combat veterans carry this diagnosis. Despite pharmacological and behavioral therapies, up to 30% of patients are still symptomatic 10 years after initial diagnosis. Recent advances in imaging have implicated changes in the limbic and autonomic corticostriatopallidothalamocortical (CSPTC) circuitry in the pathogenesis of this disease. Deep brain stimulation modulates CSPTC circuits in movement and other neuropsychiatric disorders. In this review, we discuss the salient clinical features and neurocircuitry of PTSD and propose a neuromodulation strategy for the disorder.

Deep brain stimulation for treatment-resistant depression

BACKGROUND

Major depressive disorder is a common and disabling illness and is the leading cause of disability worldwide. Despite aggressive medical, behavioral, and electroconvulsive therapies, a significant number of patients remain refractory to treatment. Deep brain stimulation (DBS) has proven efficacy in neurobehavioral disorders and, in a general sense, works by modulation of corticostriatopallidothalamocortical circuits implicated in these disorders.

METHODS

Current data, treatment rationales, and future directions are presented.

RESULTS

The two targets most commonly used for DBS in treatment-resistant depression are the subgenual cingulate gyrus and the ventral capsule/ventral striatum. Data on DBS of these regions are preliminary, with promise shown in early studies.

CONCLUSIONS

Early work suggests DBS may become a therapeutic option in treatment-resistant depression. Further study is justified given the immense burden of disease.

Surgery of the mind, mood, and conscious state: an idea in evolution

Since the beginning of recorded history, humans have sought a physical means of altering disordered behavior and consciousness. This quest has spawned numerous innovations in neurosurgery and the neurosciences, from the earliest prehistoric attempts at trepanation to the electrocortical and anatomic localization of cerebral function that emerged in the 19th century. At the start of the 20th century, the overwhelming social impact of psychiatric illness intersected with the novel but imperfect understanding of frontal lobe function, establishing a decades-long venture into the modern origin of psychosurgery, the prefrontal lobotomy. The subsequent social and ethical ramifications of the widespread overuse of transorbital lobotomies drove psychosurgery to near extinction. However, as the pharmacologic treatment of psychiatric illness was established, numerous concomitant technical and neuroscientific innovations permitted the incremental development of a new paradigm of treating the disordered mind. In this article, we retrospectively examine these early origins of psychosurgery and then look to the recent past, present, and future for emerging trends in surgery of the psyche. Recent decades have seen a revolution in minimalism, noninvasive imaging, and functional manipulation of the human cerebrum that have created new opportunities and treatment modalities for disorders of the human mind and mood. Early contemporary efforts were directed at focal lesioning of abnormal pathways, but deep-brain stimulation now aims to reversibly alter and modulate those neurologic activities responsible for not only psychiatric disorders, but also to modulate and even to augment consciousness, memory, and other elements of cerebral function. As new tools become available, the social and medical impact of psychosurgery promises to revolutionize not only neurosurgery, but also humans' capability for positively impacting life and society.

Intracranial hemorrhage after removal of deep brain stimulation electrodes

Object

Many previous studies have shown that placement of deep brain stimulation (DBS) electrodes carries a considerable risk of hemorrhage. To date, no studies have evaluated the incidence of intracranial hemorrhage after removal of DBS electrodes. The authors performed a retrospective chart review to identify the incidence and trends in hemorrhage after DBS electrode removal.

Methods

A retrospective chart review of all DBS electrodes removed at the Cleveland Clinic between October 2000 and May 2010 was performed. All patients underwent postoperative CT scanning. Each patient was evaluated for age, sex, side of placement, target, duration of lead placement, reason for removal, and medical comorbidities.

Results

A total of 78 lead removals were performed in the 10-year period (1300 leads were implanted during the same period). Of the 78 leads removed, 10 (12.8%) resulted in hemorrhages seen on postoperative CT scans. The hemorrhages were superficial cortical in 6 cases of lead removal (60%) and deep in 4 cases (40%). No statistically significant correlation to any of the factors evaluated was found. All hemorrhages were asymptomatic. The authors' retrospective study of 78 DBS lead removals revealed a high risk of intracranial hemorrhage (12.8% per lead). The risk of hemorrhage during removal is significantly greater than the risk of hemorrhage during implantation (2.0% per lead at the authors' center during the same period). There were more superficial hemorrhages, and all hemorrhages were asymptomatic.

Conclusions

Removal of DBS leads carries a significantly higher risk of postoperative hemorrhages that are seen on images but are not clinically symptomatic.

Five-year follow-up of 10 patients treated with globus pallidus internus deep brain stimulation for segmental or multisegmental dystonia

INTRODUCTION

Globus pallidus internus (GPi) deep brain stimulation (DBS) represents a validated, effective, and safe treatment for patients affected by generalized dystonia resistant to conservative treatment. Segmental and multisegmental dystonia have more recently been proposed as further indications for GPi DBS despite the lack of long-term homogenous follow-up. Here we present an original and detailed long-term follow-up (5 years) of a homogeneous population of 11 patients affected by segmental or multisegmental dystonia.

MATERIALS AND METHODS

Ten patients underwent bilateral GPi DBS electrode implantations under a Leksell stereotactic guide, with intraoperative neurophysiological monitoring. The follow-ups at 1, 3 and 5 years were collected using video-BFMDRS for motor and disability scores. The statistical analysis of the results is provided.

RESULTS

We reported a statistically significant improvement in motor and disability overall scores until 5 years after treatment. At the last follow-up, even the single motor subitems were statistically improved.

DISCUSSION

We observed a continuous and statistically significant improvement in all of the motor subitems and in the overall disability score until the 3-year follow-up. These results did not improve any further but they appeared steady at the last follow-up. We also report a significant improvement in the cranial-cervical subitems.

CONCLUSIONS

GPi DBS should definitely be considered a safe and effective treatment also for segmental and multisegmental dystonia even in cases of relevant or prevalent cranial-cervical involvement.

Deep brain stimulation in children with dystonia: experience from a tertiary care center

OBJECTIVE

To investigate the efficacy and safety of deep brain stimulation (DBS) of the globus pallidus internus (GPi) in children with dystonia.

METHODS

Retrospective chart review of patients (≤21 years) with dystonia who underwent GPi DBS. Outcome measures were assessed by the Burke-Fahn-Marsden Dystonia Rating (BFMDR) movement and disability scales pre- and post-DBS.

RESULTS

Eight patients underwent DBS; mean age of onset was 7.5 ± 4.8 years (7 were male). Mean age at DBS was 14.1 ± 4.6 years. Etiology of dystonia was primary in 6 patients and secondary in 2. There was significant improvement of BFMDR movement as well as BFMDR disability scales in 6 patients with primary dystonia with modest improvement in those scales in 2 patients with secondary dystonia. Hardware-related problems were observed in 2 and infection was noted in 1.

CONCLUSIONS

GPi DBS is an effective and safe therapy in pediatric patients with primary as well as selected cases of secondary dystonia.

Deep brain stimulation for intractable psychiatric disorders

Deep brain stimulation (DBS) has virtually replaced ablative neurosurgery for use in medication-refractory movement disorders. DBS is now being studied in severe psychiatric conditions, such as treatment-resistant depression (TRD) and intractable obsessive-compulsive disorder (OCD). Effects of DBS have been reported in ∼100 cases of OCD and ∼50 cases of TRD for seven (five common) anatomic targets. Although these published reports differ with respect to study design and methodology, the overall response rate appears to exceed 50% in OCD for some DBS targets. In TRD, >50% of patients responded during acute and long-term bilateral electrical stimulation in a different target. DBS was generally well tolerated in both OCD and TRD, but some unique, target- and stimulation-specific adverse effects were observed (e.g., hypomania). Further research is needed to test the efficacy and safety of DBS in psychiatric disorders, compare targets, and identify predictors of response.

Subthalamic nucleus targeting using interpeduncular cistern as an internal landmark

BACKGROUND

Internal landmarks for the subthalamic nucleus (STN) have been used in past. This study uses a yet-unused internal landmark to refine STN targeting.

OBJECTIVE

To determine the effect of the width of the interpeduncular cistern (IPC) on STN targeting during placement of deep brain stimulation (DBS) for Parkinson disease.

METHODS

Fifty consecutive patients with Parkinson disease underwent 90 STN DBS implantations. X, Y, and Z coordinates for the tip of the DBS electrodes and the active contact were recorded. Internal landmarks such as width of the third ventricle, width of IPC at a predefined point, and anterior commissure-posterior commissure length were measured. Statistical analysis was done using linear regression analysis and Pearson correlation coefficient.

RESULTS

The average IPC diameter at the predefined point was 7.59 mm (range, 5- to 14 mm). Average X, Y, and Z coordinates for the location of the tip of lead were 11.5, -3.5, -5.4, and those of the location of active contact were 12.5, -1.9, -1.4 from the midcommissural point. The mediolateral location of the tip of the DBS as well as the location of the active contact for long-term stimulation were greatly dependent on IPC width (r = 0.83) (P = .0022).

CONCLUSION

The width of the IPC is a strong predictor of laterality of STN DBS electrode placement in patients with Parkinson disease. It can be used as an additional internal landmark for refining STN targeting using the simple formula X coordinate for STN target = 0.6 × IPC width + 7 mm.

Subthalamic nucleus high-frequency stimulation generates a concomitant synaptic excitation-inhibition in substantia nigra pars reticulata

Deep brain stimulation is an efficient treatment for various neurological pathologies and a promising tool for neuropsychiatric disorders. This is particularly exemplified by high-frequency stimulation of the subthalamic nucleus (STN-HFS), which has emerged as an efficient symptomatic treatment for Parkinson's disease. How STN-HFS works is still not fully elucidated. With dual patch-clamp recordings in rat brain slices, we analysed the cellular responses of STN stimulation on SNr neurons by simultaneously recording synaptic currents and firing activity. We showed that STN-HFS caused an increase of the spontaneous spiking activity in half of SNr neurons while the remaining ones displayed a decrease. At the synaptic level, STN stimulation triggered inward current in 58% of whole-cell recorded neurons and outward current in the remaining ones. Using a pharmacological approach, we showed that STN-HFS-evoked responses were mediated in all neurons by a balance between AMPA/NMDA receptors and GABA(A) receptors, whose ratio promotes either a net excitation or a net inhibition. Interestingly, we observed a higher excitation occurrence in 6-hydroxydopamine (6-OHDA)-treated rats. In vivo injections of phaseolus revealed that GABAergic pallido-nigral fibres travel through the STN whereas striato-nigral fibres travel below it. Therefore, electrical stimulation of the STN does not only recruit glutamatergic axons from the STN, but also GABAergic passing fibres probably from the globus pallidus. For the first time, we showed that STN-HFS induces concomitant excitatory-inhibitory synaptic currents in SNr neurons by recruitment of efferences and passing fibres allowing a tight control on basal ganglia outflow.