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.

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.

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.