Diffuse Leptomeningeal Glioneuronal Tumor: First Description of Metastasis to the Lung and Bone Marrow.

Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a rare neoplasm of the central nervous system (CNS) that primarily affects the leptomeninges. However, it can also involve the brain parenchyma and spinal cord. We report the first case of metastasis of this primary CNS tumor to the lung and bone marrow. An 18-year-old male was diagnosed with DLGNT through meningeal biopsy after multiple events of transient neurologic signs and symptoms that included recurrent episodes of encephalopathy, seizures, cerebral vasospasms, cranial nerve palsy, and urinary dysfunction. Five months after diagnosis, the patient presented with pancytopenia and pulmonary effusion. At that time, he was being treated with temozolomide, after radiation treatment to the brain and spinal cord. Bone marrow biopsy and pleural cytology revealed systemic metastases from the primary CNS tumor. He was then treated with chemotherapy with carboplatin and vincristine which improved his condition for two and a half months. Unfortunately, the patient died of a high systemic metastatic burden. Primary CNS tumors rarely produce systemic metastases, and this is the first report of DLGNT with bone marrow and pulmonary metastases. Chemotherapy with carboplatin and vincristine should be considered as a treatment for patients with DLGNT, as the patient presented a systemic response with clinical and radiological improvement.

Use of a Pericranial Flap Technique for Deep Brain Stimulation Hardware Protection and Improved Cosmesis.

OBJECTIVES: Deep brain stimulation (DBS) has become an established neuromodulation therapy; however, surgical site complications such as hardware skin erosion remain an important risk and can predispose to infection, requiring explantation of the system. Nuances of surgical technique can affect wound healing, cosmetic outcome, comfort, and risk of infection. In this study, we describe our experience with a layered closure technique using a vascularized pericranial flap for improving cosmesis and protection of the implanted hardware against skin erosion and infection. MATERIALS AND METHODS: We retrospectively reviewed 636 individuals (746 lead implantations) who underwent DBS surgery by a single academic neurosurgeon between 2001 and 2020. A layered pericranial flap closure technique for the burr-hole and connector sites was instituted in 2015. We assessed the effects of a multimodal infection prevention approach that included the pericranial flap on hardware complication rates compared with the premultimodality cohort, and we report the nuances of the technique. RESULTS: In our institutional experience, we found that implementation of a pericranial flap closure technique can enhance the subjective cosmetic result at the burr-hole cover site and increase patient comfort and satisfaction. In addition, we found a decrease in hardware infection rates in the current cohort with a multimodal infection prevention regimen that includes the pericranial-flap technique (n = 256, 2015-2020 period) to 1.2% (p = 0.006), from 6.9% in the earlier cohort (n = 490, 2001-2015 period). CONCLUSIONS: The report highlights the potential of a pericranial-flap closure technique as a surgical adjunct to improve DBS surgical site healing and cosmesis and may, as part of a multimodal strategy, contribute to decreased risk of skin breakdown and hardware infection.

Practical methods for segmentation and calculation of brain volume and intracranial volume: a guide and comparison.

Background: Accurate segmentation and calculation of total brain volume (BV) and intracranial volume (ICV) (further-volumetry) may serve various clinical tasks and research studies in neuroscience. Manual segmentation is extremely time consuming. There is a relative lack of published broad recommendations and comparisons of tools for automated volumetry, especially for users without expertise in computer science, for settings with limited resources, and when neuroimaging quality is suboptimal due to clinical circumstances. Our objective is to decrease the barrier to entry for research and clinical groups to perform volumetric cranial imaging analysis using free and reliable software tools. Methods: Automated volumetry from computed tomography (CT)/magnetic resonance imaging (MRI) scans was accomplished using 3D Slicer (v. 4.11.0), FreeSurfer (v. 7.1.1), and volBrain (v. 1.0) in a cohort of 39 patients with ischemic middle cerebral artery territory brain infarcts in the acute stage. Visual inspection for accuracy was also performed. Statistical analysis included coefficient of determination (R2) and Bland-Altman (B-A) plots. A multifaceted comparison between 3D Slicer, FreeSurfer, and volBrain from practical user perspective was performed to compile a list of distinguishing features. Results: BV: FreeSurfer, 3D Slicer, and volBrain provide similar estimations when high quality T1-MRI scans with 1 mm slices (3D scans) are available, whereas 3 mm and thicker slices (2D scans) introduce a dispersion in results. ICV: the most accurate volumetry is provided by 3D Slicer using CT scans. volBrain uses T1-MRIs and also provides good results which agree with 3D Slicer. Both of these methods may be more trustworthy than T1 MRI-derived FreeSurfer calculations. Conclusions: All three studied tools of automated intracranial and brain volumetry-3D Slicer, FreeSurfer, and volBrain-are free, reliable, require no complex programming, but still have certain limitations and significant differences. Based on our investigation findings, the readers should be able to select the right volumetry tool and neuroimaging study, and then follow provided step-by-step instructions to accomplish specific volumetry tasks.

Surgical Treatment of Propriospinal Myoclonus: A Case Report.

Propriospinal myoclonus (PSM) is a rare segmental movement disorder characterized by repetitive irregular myoclonic jerks of the trunk and/or axial limbs at the resting state. It is imperative to make a correct diagnosis as other movement disorders can be mistaken for or mask PSM. Therefore, a battery of neuroimaging and neurophysiological testing must be undertaken. In our case report, we discuss a patient who was diagnosed with PSM concurrently with cervical degenerative stenosis and then had a successful outcome via surgical decompression and arthrodesis of the cervical spine. We documented the patient's postoperative course and achievement of complete remission, sustained at a 41-month follow-up. We then grouped our case together with five other PSM cases in the literature to offer readers a broader context of the role of surgical spinal intervention in ameliorating PSM.

Reproducible asystole following vagal nerve stimulator lead replacement: a case report.

BACKGROUND: Vagal nerve stimulation (VNS) is approved therapy for the treatment of intractable epilepsy. The stimulation of either nerve, left or right, is effective. However, due to the anatomic and physiological effects of cardiac innervation, the right vagus nerve is typically avoided in order to minimize the risk of cardiac bradyarrhythmias. The location of the VNS lead contacts on the nerve can also have an effect, namely, more distally placed contacts have been associated with lower risk of cardiac arrhythmias, presumably by avoiding vagal cervical cardiac branches; however, our case demonstrates reproducible asystole despite left sided, distal VNS lead placement. CASE PRESENTATION: We report a 28-year-old male patient with pharmacoresistant generalized clonic-tonic seizures. The VNS therapy with 1.5 mA output and 16% duty cycle drastically reduced his seizure burden for several years. The breakthrough seizures along with stabbing pain episodes at the implantable pulse generator (IPG) site have prompted the VNS lead revision surgery with new lead contacts placed more caudally than the old contacts. However, the intraoperative device interrogation with 1 mA output resulted in immediate asystole for the duration of stimulation and it was reproducible until the output was decreased to 0.675 mA. CONCLUSIONS: Our case highlights the possibility of new severe cardiac bradyarrhythmias following surgical VNS lead replacements even in patients without preoperatively known clinical side effects. We suggest preoperative electrocardiography and cardiology consultation for detected abnormalities for all patients undergoing new VNS implantations, as well as revision surgeries for VNS malfunctions. Intraoperatively, the surgeon and anesthesia team should be vigilant of cardiac rhythms and prepared for the immediate management.

Allergy Considerations in Implanted Neuromodulation Devices.

OBJECTIVES: Allergic reactions are rare and poorly understood complications of neuromodulation device implantation. There are currently no guidelines for management of allergic reactions to these devices and their components. Here we review the published cases of allergic reactions to implanted neuromodulatory devices and leverage the experiences of other specialties that deal with similar complications to formulate recommendations for prevention and management. MATERIALS AND METHODS: A review and assessment of the literature. RESULTS: Allergic reactions to a number of implantable devices have been observed and published. In dentistry and orthopedics, metals such as nickel are the most frequent cause of allergic reactions. In interventional cardiology, where devices closely resemble neuromodulatory devices, titanium, silicone, and polyurethanes are the most common causes of allergic reactions. In neurosurgery, allergic reactions to implantable neuromodulatory devices are rare, and we summarize 13 cases published to date. Such allergic reactions generally present as local dermatitis, erythema, and pruritus, which can be difficult to distinguish from surgical site infection. In one published case, symptoms resolved with corticosteroid treatment, but all other cases required explantation. The successful reimplantation with a modified device was reported in some cases. CONCLUSIONS: Patients should be screened for a personal history of contact allergy before implantation procedures. A multidisciplinary approach to suspected cases of postoperative allergic reactions involving collaboration between neurosurgeons and other implanting physicians, dermatologists or allergists, and device manufacturers is recommended. In cases where an allergic reaction is suspected, an infectious etiology should be ruled out first. Clinical suspicion can then be supported with the use of patch testing, interpreted by an experienced dermatologist or allergist. If patch testing supports an allergic etiology, the implanting physician and the device manufacturer can work together to modify the device for safe reimplantation.

Nucleus Basalis of Meynert Stimulation for Dementia: Theoretical and Technical Considerations.

Deep brain stimulation (DBS) of nucleus basalis of Meynert (NBM) is currently being evaluated as a potential therapy to improve memory and overall cognitive function in dementia. Although, the animal literature has demonstrated robust improvement in cognitive functions, phase 1 trial results in humans have not been as clear-cut. We hypothesize that this may reflect differences in electrode location within the NBM, type and timing of stimulation, and the lack of a biomarker for determining the stimulation's effectiveness in real time. In this article, we propose a methodology to address these issues in an effort to effectively interface with this powerful cognitive nucleus for the treatment of dementia. Specifically, we propose the use of diffusion tensor imaging to identify the nucleus and its tracts, quantitative electroencephalography (QEEG) to identify the physiologic response to stimulation during programming, and investigation of stimulation parameters that incorporate the phase locking and cross frequency coupling of gamma and slower oscillations characteristic of the NBM's innate physiology. We propose that modulating the baseline gamma burst stimulation frequency, specifically with a slower rhythm such as theta or delta will pose more effective coupling between NBM and different cortical regions involved in many learning processes.

Frameless Functional Stereotactic Approaches.

The stereotactic frame has served as the gold standard apparatus for accurate and precise targeting of deep brain structures since 1947. Despite passing the test of time, the stereotactic frame has several limitations from the perspective of both neurosurgeons and patients. Therefore, there was a need to develop a frameless system that had equivalent accuracy and reliability to the frame. This need was met with 3 commercially available frameless stereotactic systems designed specifically for deep brain stimulation surgery: Nexframe, STarFix, and ClearPoint. Over the past decade, the frameless and frame-based systems have been extensively investigated by numerous studies and found to be equivalent in experimental and clinical accuracy as well as in clinical outcomes. This chapter summarizes the findings of those studies along with the discussion of sources of stereotactic errors. The procedural aspects, advantages, and disadvantages of each frameless system are reviewed. Frameless stereotaxy is a safe, accurate, and effective technique for functional stereotactic approaches and provides a viable alternative to the frame-based systems.

The role of anticoagulants, antiplatelet agents, and their reversal strategies in the management of intracerebral hemorrhage.

New anticoagulant and antiplatelet medications have been approved and are prescribed with increased frequency. Intracranial hemorrhage is associated with the use of these medications. Therefore, neurosurgeons need to be aware of these new medications, how they are different from their predecessors, and the strategies for the urgent reversal of their effects. Utilization of intraluminal stents by endovascular neurosurgeons has resulted in the need to have a thorough understanding of antiplatelet agents. Increased use of dabigatran, rivaroxaban, and apixaban as oral anticoagulants for the treatment of atrial fibrillation and acute deep venous thrombosis has increased despite the lack of known antidotes to these medications.