Tractography-Enhanced Biopsy of Central Core Motor Eloquent Tumours: A Simulation-Based Study.

Safe Trajectory planning for navigation guided biopsy (nBx) of motor eloquent tumours (METs) is important to minimise neurological morbidity. Preliminary clinical data suggest that visualisation of the corticospinal tract (CST) and its relation to the tumour may aid in planning a safe trajectory. In this article we assess the impact of tractography in nBx planning in a simulation-based exercise. This single centre cross-sectional study was performed in March 2021 including 10 patients with METs divided into 2 groups: (1) tractography enhanced group (T-nBx; n = 5; CST merged with volumetric MRI); (2) anatomy-based group (A-nBx; n = 5; volumetric MRI only). A biopsy target was chosen on each tumour. Volunteer neurosurgical trainees had to plan a suitable biopsy trajectory on a Stealth S8® workstation for all patients in a single session. A trajectory safety index (TSI) was devised for each trajectory. Data collection and analysis included a comparison of trajectory planning time, trajectory/lobe changes and TSI. A total of 190 trajectories were analysed based on participation from 19 trainees. Mean trajectory planning time for the entire cohort was 225.1 ± 21.97 s. T-nBx required shorter time for planning (p = 0.01). Mean trajectory changes and lobe changes made per biopsy were 3.28 ± 0.29 and 0.45 ± 0.08, respectively. T-nBx required fewer trajectory/lobe changes (p = 0.01). TSI was better in the presence of tractography than A-nBx (p = 0.04). Neurosurgical experience of trainees had no significant impact on the measured parameters despite adjusted analysis. Irrespective of the level of neurosurgical training, surgical planning of navigation guided biopsy for METs may be achieved in less time with a safer trajectory if tractography imaging is available.

Neuromate® robot-assisted ventricular catheter insertion.

BACKGROUND AND IMPORTANCE: Insertion of ventricular catheters into small ventricles may require image guidance. Several options exist, including ultrasound guidance, frameless, and frame-based stereotactic approaches. There is no literature on management options when conventional image guidance fails to cannulate the ventricle. The accuracy of the robotic arm is well established in functional and epilepsy surgery. We report the first case using the Neuromate® robot for the placement of a shunt ventricular catheter into the lateral ventricle after a failed attempt with a more commonly used frameless electromagnetic navigation system. CLINICAL PRESENTATION: A 30-year-old man had twice previously undergone foramen magnum decompression for a Chiari 1 malformation. He subsequently developed a significant cervical syrinx with clinical deterioration and a decision was made to place a ventriculoperitoneal shunt. As the ventricles were small, frameless electromagnetic navigation was used but the ventricle could not be cannulated. The Neuromate® robot was subsequently used to place the ventricular catheter successfully. CONCLUSION: Neuromate® robot-assisted ventricular catheter placement may be considered when difficulty is experienced with more commonly used image guidance techniques.

Probabilistic mapping of deep brain stimulation in childhood dystonia.

OBJECTIVES: In adults with dystonia Probabilistic Stimulation Mapping (PSM) has identified putative "sweet spots" for stimulation. We aimed to apply PSM to a cohort of Children and Young People (CYP) following DBS surgery. METHODS: Pre-operative MRI and post-operative CT images were co-registered for 52 CYP undergoing bilateral pallidal DBS (n = 31 genetic/idiopathic dystonia, and n = 21 Cerebral Palsy (CP)). DBS electrodes (n = 104) were automatically detected, and Volumes of Tissue Activation (VTA) derived from individual patient stimulation settings. VTAs were normalised to the MNI105 space, weighted by percentage improvement in Burke-Fahn-Marsden Dystonia Rating scale (BFMDRS) at one-year post surgery and mean improvement was calculated for each voxel. RESULTS: For the genetic/idiopathic dystonia group, BFMDRS improvement was associated with stimulation across a broad volume of the GPi. A spatial clustering of the upper 25th percentile of voxels corresponded with a more delineated volume within the posterior ventrolateral GPi. The MNI coordinates of the centroid of this volume (X = -23.0, Y = -10.5 and Z = -3.5) were posterior and superior to the typical target for electrode placement. Volume of VTA overlap with a previously published "sweet spots" correlated with improvement following surgery. In contrast, there was minimal BFMDRS improvement for the CP group, no spatial clustering of efficacious clusters and a correlation between established "sweet spots" could not be established. CONCLUSIONS: PSM in CYP with genetic/idiopathic dystonia suggests the presence of a "sweet spot" for electrode placement within the GPi, consistent with previous studies. Further work is required to identify and validate putative "sweet spots" across different cohorts of patients.

Occam or Hickham? The diagnostic dilemma of an inflammatory brain lesion in the setting of pulmonary aspergillosis and previous neurosurgery.

INTRODUCTION: Occam's Razor is a precept which invites one to consider the simplest and most unifying diagnosis as correct. In the modern era, clinical diagnosis remains critical in selecting appropriate therapies yet grows ever more complex with increased information from diagnostic technologies, but not always with sufficient granularity to answer the clinical question with certainty. We present an example of this dilemma in a patient with complex partial seizures on a background of pulmonary aspergillosis and historic clipping of a middle cerebral artery (MCA) aneurysm. CASE DESCRIPTION: A 69-year-old female presented with progressive headaches, temporal lobe seizures, poor short-term memory and weight loss. She had suffered a subarachnoid haemorrhage 22 years earlier requiring surgical repair of a right MCA aneurysm. She was treated for breast cancer in 2006 followed by pulmonary aspergilloma in 2014 for which systemic antifungals were discontinued due to toxicity. Imaging revealed a right temporal inflammatory lesion adjacent to the aneurysm clip. Gastrointestinal toxicity and haemoptysis complicated the clinical and radiological response to systemic steroids. Cerebral aspergillosis was considered given her medical history despite an equivocal fungal screen, but intolerable side effects negated the continued use of systemic antifungals. Surgical exploration to establish a definitive diagnosis and potentially treat the underlying cause was recommended despite the high surgical risk involved and subsequently revealed a foreign body type granuloma, and excluded aspergillosis. Tuberculosis and other granulomatous disease processes were excluded. CONCLUSION: This case illustrates the importance of pathological diagnosis to guide therapy and reminds us that the occasional patient will encounter multiple, rare and unrelated diseases during their lifetime. A high index of suspicion is necessary in patients who have undergone surgical aneurysm repair involving muslin as it may be subject to secondary infection and or granuloma formation many years later.

Globus Pallidus Internus Deep Brain Stimulation for Dystonic Opisthotonus in Adult-Onset Dystonia: A Personalized Approach.

INTRODUCTION: Dystonic opisthotonus is defined as a backward arching of the neck and trunk, which ranges in severity from mild backward jerks to life-threatening prolonged severe muscular spasms. It can be associated with generalized dystonic syndromes or, rarely, present as a form of axial truncal dystonia. The etiologies vary from idiopathic, genetic, tardive, hereditary-degenerative, or associated with parkinsonism. We report clinical cases of dystonic opisthotonus associated with adult-onset dystonic syndromes, that benefitted from globus pallidus internus (GPi) deep brain stimulation (DBS). METHODS: Clinical data from patients with dystonic syndromes who underwent comprehensive medical review, multidisciplinary assessment, and tailored medical and neurosurgical managements were prospectively analyzed. Quantification of dystonia severity pre- and postoperatively was performed using the Burke-Fahn-Marsden Dystonia Rating Scale and quantification of overall pain severity was performed using the Visual Analog Scale. RESULTS: Three male patients, with age of onset of the dystonic symptoms ranging from 32 to 51 years old, were included. Tardive dystonia, adult-onset dystonia-parkinsonism and adult-onset idiopathic axial dystonia were the etiologies identified. Clinical investigation and management were tailored according to the complexity of the individual presentations. Although they shared common clinical features of adult-onset dystonia, disabling dystonic opisthotonus, refractory to medical management, was the main indication for GPi-DBS in all patients presented. The severity of axial dystonia ranged from disturbance of daily function to life-threatening truncal distortion. All three patients underwent bilateral GPi DBS at a mean age of 52 years (range 48-55 years), after mean duration of symptoms prior to DBS of 10.7 years (range 4-16 years). All patients showed a rapid and sustained clinical improvement of their symptoms, notably of the dystonic opisthotonos, at postoperative follow-up ranging from 20 to 175 months. In some, the ability to resume activities of daily living and reintegration into the society was remarkable. CONCLUSION: Adult-onset dystonic syndromes predominantly presenting with dystonic opisthotonus are relatively rare. The specific nature of dystonic opisthotonus remains a treatment challenge, and thorough investigation of this highly disabling condition with varying etiologies is often necessary. Although patients may be refractory to medical management and botulinum toxin injection, Globus pallidus stimulation timed and tailored provided symptomatic control in this cohort and may be considered in other carefully selected cases.

Deep brain stimulation in the management of paediatric neuropsychiatric conditions: Current evidence and future directions.

INTRODUCTION: Neurosurgery has provided an alternative option for patients with refractory psychiatric indications. Lesion procedures were the initial techniques used, but deep brain stimulation (DBS) has the advantage of relative reversibility and adjustability. This review sets out to delineate the current evidence for DBS use in psychiatric conditions, with an emphasis on the paediatric population, highlighting pitfalls and opportunities. METHODS: A systematic review of the literature was conducted on studies reporting the use of DBS in the management of psychiatric disorders. The PRISMA guidelines were employed to structure the review of the literature. Data was discussed focusing on the indications for DBS management of psychiatric conditions in the paediatric age group. RESULTS: A total of seventy-three full-text papers reported the use of DBS surgery for the management of psychiatric conditions matching the inclusion criteria. The main indications were Tourette Syndrome (GTS) (15 studies), Obsessive Compulsive Disorder (OCD) (20), Treatment Resistant Depression (TRD) (27), Eating Disorders (ED) (7) and Aggressive Behaviour and self-harm (AB) (4). Out of these, only 11 studies included patients in the paediatric age group (≤18 years-old). Among the paediatric patients, the indications for surgery included GTS, AB and ED. CONCLUSIONS: The application of deep brain stimulation for psychiatric indications has progressed at a steady pace in the adult population and at a much slower pace in the paediatric population. Future studies in children should be done in a trial setting with strict and robust criteria. A move towards personalising DBS therapy with new stimulation paradigms will provide new frontiers and possibilities in this growing field.

Deep Brain Stimulation of the Internal Pallidum in Lesch-Nyhan Syndrome: Clinical Outcomes and Connectivity Analysis.

BACKGROUND: Lesch-Nyhan syndrome (LNS) is a rare genetic disorder characterized by a deficiency of hypoxanthine-guanine phosphoribosyltransferase enzyme. It manifests during infancy with compulsive self-mutilation behavior associated with disabling generalized dystonia and dyskinesia. Clinical management of these patients poses an enormous challenge for medical teams and carers. OBJECTIVES: We report our experience with bilateral deep brain stimulation (DBS) of the globus pallidus internus (GPi) in the management of this complex disorder. MATERIALS AND METHODS: Preoperative and postoperative functional assessment data prospectively collected by a multidisciplinary pediatric complex motor disorders team, including imaging, neuropsychology, and neurophysiology evaluations were analyzed with regards to motor and behavioral control, goal achievement, and patient and caregivers' expectations. RESULTS: Four male patients (mean age 13 years) underwent DBS implantation between 2011 and 2018. Three patients received double bilateral DBS electrodes within the posteroventral GPi and the anteromedial GPi, whereas one patient had bilateral electrodes placed in the posteroventral GPi only. Median follow-up was 47.5 months (range 22-98 months). Functional improvement was observed in all patients and discussed in relation to previous reports. Analysis of structural connectivity revealed significant correlation between the involvement of specific cortical regions and clinical outcome. CONCLUSION: Combined bilateral stimulation of the anteromedial and posteroventral GPi may be considered as an option for managing refractory dystonia and self-harm behavior in LNS patients. A multidisciplinary team-based approach is essential for patient selection and management, to support children and families, to achieve functional improvement and alleviate the overall disease burden for patients and caregivers.

Subthalamic Nucleus Deep Brain Stimulation in Post-Infarct Dystonia.

Dystonia secondary to cerebral infarcts presents months to years after the initial insult, is usually unilateral and causes significant morbidity. Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is established as the most frequent target in the management of the dystonic symptoms. We report our experience with subthalamic nucleus (STN) DBS in 3 patients with post-infarct dystonia, in whom GPi DBS was not confidently possible due to the presence of striatal infarcts. Two patients had unilateral STN DBS implantation, whereas the third patient had bilateral STN DBS implantation for bilateral dystonic symptoms. Prospectively collected preoperative and postoperative functional assessment data including imaging, medication and neuropsychology evaluations were analyzed with regard to symptom improvement. Median follow-up period was 38.3 months (range 26-43 months). All patients had clinically valuable improvements in dystonic symptoms and pain control despite variable improvements in the Burke-Fahn-Marsden dystonia rating scores. In our series, we have demonstrated that STN DBS could be an alternative in the management of post-infarct dystonia in patients with abnormal striatal anatomy which precludes GPi DBS. A multidisciplinary team-based approach is essential for patient selection and management.

Upper Cervical Spinal Cord Stimulation as an Alternative Treatment in Trigeminal Neuropathy.

OBJECTIVE: To describe the indications and outcomes of upper cervical cord stimulation in trigeminal neuropathy. METHODS: A consecutive single-center series of patients was retrospectively reviewed. It included 12 patients with trigeminal neuropathy treated with upper cervical spinal cord stimulation. Clinical features, complications, and outcomes were reviewed. RESULTS: All patients had a successful trial before the definitive implantation of a spinal cord stimulator at the level of the craniocervical junction. The mean follow-up period was 4.4 years (range, 0.3-21.1 years). The average coverage in the pain zone was 72% and the median baseline, trial, and postoperative numeric rating scale (NRS) was 7, 3, and 3, respectively. When compared with the baseline, the mean reduction achieved in the postoperative average numeric rating scale was 4 points, accounting for a 57.1% pain reduction. The long-term failure rate was 25%. CONCLUSIONS: Despite there being enough evidence to consider upper cervical spinal cord stimulation as an effective treatment for patients with neuropathic trigeminal pain, a randomized controlled trial is needed to fully assess its indications and outcomes and compare it with other therapeutic approaches.

Rapid Clinical Course of Multiple Metastatic Cerebral Angiosarcoma.

Central nervous system (CNS) angiosarcoma, both primary and secondary, is an exceptionally rare malignant tumor. The behaviour of angiosarcoma is one of rapid progression with early metastatic spread but as with all sarcomas, the primary site may not clinically evident by the time metastases develop. Identification of the primary site of origin is masked by the carpet-like growth pattern that may occur in the left atrium, the most frequently encountered primary site for angiosarcoma. This rare tumor presents many diagnostic challenges. We describe the clinical and neuropathologic features of two patients with angiosarcoma of the brain and review the previously published cases described to date.