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Background and Purpose The goal of this study was to systematically review the utility of serum biomarkers in the setting of ischemic stroke (IS) to predict long-term outcome. Methods A systematic literature review was performed using the PubMed and MEDLINE databases for studies published between 1986-2018. All studies assessing long-term functional outcome (defined as 30 days or greater) following IS with respect to serum biomarkers were included. Data were extracted and pooled using a meta-analysis of odds ratios. Results Of the total 2928 articles in the original literature search, 183 studies were ultimately selected. A total of 127 serum biomarkers were included. Biomarkers were grouped into several categories: inflammatory (32), peptide/enzymatic (30), oxidative/metabolic (28), hormone/steroid based (23), and hematologic/vascular (14). The most commonly studied biomarkers in each category were found to be CRP, S100β, albumin, copeptin, and D-dimer. With the exception of S100β, all were found to be statistically associated with >30-day outcome after ischemic stroke. Conclusions Serum-based biomarkers have the potential to predict functional outcome in IS patients. This meta-analysis has identified CRP, albumin, copeptin, and D-dimer to be significantly associated with long-term outcome after IS. These biomarkers have the potential to serve as a platform for prognosticating stroke outcomes after 30 days. These serum biomarkers, some of which are routinely ordered, can be combined with imaging biomarkers and used in artificial intelligence algorithms to provide refined predictive outcomes after injury. Ultimately these tools will assist physicians in providing guidance to families with regards to long-term independence of patients.

OBJECTIVE The discovery of dural lymphatics has spurred interest in the mechanisms of drainage of interstitial fluid from the CNS, the anatomical components involved in clearance of macromolecules from the brain, mechanisms of entry and exit of immune components, and how these pathways may be involved in neurodegenerative diseases and cancer metastasis. In this study the authors describe connections between a subset of arachnoid granulations (AGs) and the venous circulation via intradural vascular channels (IVCs), which stain positively with established lymphatic markers. The authors postulate that the AGs may serve as a component of the human brain’s lymphatic system. METHODS AGs and IVCs were examined by high-resolution dissection under stereoscope bilaterally in 8 fresh and formalin-fixed human cadaveric heads. The superior sagittal sinus (SSS) and adjacent dura mater were immunostained with antibodies against Lyve-1 (lymphatic marker), podoplanin (lymphatic marker), CD45 (panhematopoietic marker), and DAPI (nuclear marker). RESULTS AGs can be classified as intradural or interdural, depending on their location and site of drainage. Interdural AGs are distinct from the dura, adhere to arachnoid membranes, and occasionally open directly in the inferolateral wall or floor of the SSS, although some cross the infradural folds of the dura’s inner layer to meet with intradural AGs and IVCs. Intradural AGs are located within the leaflets of the dura. The total number of openings from the AGs, lateral lacunae, and cortical veins into the SSS was 45 ± 5.62 per head. On average each cadaveric head contained 6 ± 1.30 intradural AGs. Some intradural AGs do not directly open into the SSS and use IVCs to connect to the venous circulation. Using immunostaining methods, the authors demonstrate that these tubular channels stain positively with vascular and lymphatic markers (Lyve-1, podoplanin). CONCLUSIONS AGs consist of two subtypes with differing modes of drainage into the SSS. A subset of AGs located intradurally use tubular channels, which stain positively with vascular and lymphatic markers to connect to the venous lacunae and ultimately to the SSS. The present study suggests that AGs may function as a component of brain lymphatics. This finding has important clinical implications for cancer metastasis to and from the CNS and may shed light on mechanisms of altered clearance of macromolecules in the setting of neurodegenerative diseases.

Aniridia is a panocular condition characterized by impaired eye development and vision, which is mainly due to the haploinsufficiency of the paired-box-6 (PAX6) gene. Like what is seen in aniridia patients, Pax6-deficient mice Pax6(Sey-Neu/+) exhibit a varied degree of ocular damage and impaired vision. Our previous studies showed that theses phenotypes were partially rescued by PD0325901, a mitogen-activated protein kinase kinase (MEK or MAP2K) inhibitor. In this study, we assessed the long-term efficacy of PD0325901 treatment in retinal health and visual behavior. At about one year after the postnatal treatment with PD0325901, Pax6(Sey-Neu/+) mice showed robust improvements in retina size and visual acuity, and the elevated intraocular pressure (IOP) was also alleviated, compared to age-matched mice treated with vehicles only. Moreover, the Pax6(Sey-Neu/+) eyes showed disorganized retinal ganglion cell (RGC) axon bundles and retinal layers, which we termed as hotspots. We found that the PD treatment reduced the number and size of hotspots in the Pax6(Sey-Neu/+) retinas. Taken together, our results suggest that PD0325901 may serve as an efficacious intervention in protecting retina and visual function in aniridia-afflicted subjects.

Retinal ganglion cells (RGCs) exhibit compartmentalized organization, receiving synaptic inputs through their dendrites and transmitting visual information from the retina to the brain through the optic nerve. Little is known about the structure of RGC axon bundles extending from individual RGC somas to the optic nerve head (ONH) and how they respond to disease insults. We recently introduced visible-light optical coherence tomography fibergraphy (vis-OCTF), a technique for directly visualizing and analyzing mouse RGC axon bundlesin vivo. In this study, we validated vis-OCTF's ability to quantify RGC axon bundles with an increased number of RGCs using mice deficient in BCL2-associated X protein (BAX−/−). Next, we performed optic nerve crush (ONC) injury on wild-type (WT) mice and showed that the changes in RGC axon bundle width and thickness were location-dependent. Our work demonstrates the potential of vis-OCTF to longitudinally quantify and track RGC damage at single axon bundle level in optic neuropathies.SIGNIFICANCE STATEMENTNearly all clinical and preclinical studies measure the retinal nerve fiber (RNFL) thickness as the sole indicator of retinal ganglion cell (RGC) damage without investigating RGC axon bundles directly. We demonstrated visible-light optical coherence tomography fibergraphy (vis-OCTF) to directly quantify global and regional RGC axon bundle organizationsin vivoas a new biomarker for RGC health. We validatedin vivovis-OCTF measures using both confocal microscopy of the immunostained flat-mounted retina and numerical simulations. Vis-OCTF for monitoring RGC axon bundle organization has the potential to bring new insight into RGC damage in optic neuropathies.

Low bioavailability of topically applied drugs remains a significant challenge for long-term glaucoma therapy. To enhance drug delivery efficiency, we developed dendrimer gel particles that collectively exhibit structural benefits of dendrimer, hydrogel, and particles, using the inverse emulsion method coupled with the highly efficient aza-Michael addition reaction (IEaMA). This hierarchical approach would maximize the utility of the structural features of existing ocular drug delivery systems. We have tested the delivery efficiency and efficacy of two first-line antiglaucoma drugs, brimonidine tartrate (BT) and timolol maleate (TM), which were loaded into dendrimer gel particles of various sizes, i.e., nDHP (nano-in-nano dendrimer hydrogel particles, ~200 nm), μDHP3 (3 μm), and μDHP10 (9 μm). We found that nDHP was superior to μDHP3 and μDHP10 in terms of cytocompatibility, degradability, drug release kinetics, and corneal permeability. The nDHPs increased drug corneal permeability by 17-fold compared to plain drug solution and enabled zero-order prolonged drug release kinetics. The nDHP-based formulation demonstrated pronounced IOP-lowering effects in both single-dose test and 7-day chronic daily dosing test in both Brown Norway rats and glaucoma mice. Taken together, we have developed nano-in-nano dendrimer gel particles for precise dosing and enabling sustained and synergistic efficacy of antiglaucoma drugs, which could be clinically impactful for improving glaucoma treatment.

A Correction to this paper has been published: https://doi.org/10.1038/s41536-021-00125-3

Neuroanatomy laboratory training is crucial for the education of neurosurgery residents and medical students. Since the brain is a complex and three-dimensional structure, it is challenging to understand the anatomical relationship of the cortex, internal structures, arteries, and veins without appropriate adjuncts. Several injection agents&mdash, including the inks/dyes, latex, polyester, acrylic resins, phenol, polyethylene glycol, and phenoxyethanol&mdash, have been explored. Colored silicon injection protocols for the head and neck vessels&rsquo, perfusion have greatly aided the study of neuroanatomy and surgical planning. This report presents a colored silicone injection method in detail, and also highlights the technical shortcomings of the standard techniques and workarounds for common challenges during 35 human cadaveric head injections. The human cadaveric head preparation and the coloring of the head vessels are divided into decapitation, tissue fixation with 10% formalin, the placement of the Silastic tubing into the parent vessels, the cleaning of the vessels from clots, and the injection of the colored silicone into the vessels. We describe the technical details of the preparation, injection, and preservation of cadaveric heads, and outline common challenges during colored silicone injection, which include the dislocation of the Silastic tubing during the injection, the injection of the wrong or inappropriate colored silicone into the vessel, intracranial vessel perforation, the incomplete silicone casting of the vessel, and silicone leakage from small vessels in the neck. Solutions to these common challenges are provided. Ethyl alcohol fixed, colored human heads provided the long-term preservation of tissue, and improve the sample consistency and preservation for the teaching of neuroanatomy and surgical technique.

While full integration of robotic surgery has been achieved in other surgical domains, its transition into neurosurgery has been more prolonged, especially with respect to pituitary surgery. The confined working space and precise maneuvers required in endoscopic endonasal surgery makes development of an efficacious and safe robotic system difficult. Nevertheless, preclinical studies have attempted to demonstrate the feasibility of the da Vinci Surgical System (Intuitive Surgical, Sunnyvale, CA) in both transnasal and transoral approaches. In addition, unique robotics such as the concentric tube robot have been created. This system is optimized specifically for anterior skull base surgery with smaller shaft diameter arms and improved maneuverability in tight corridors. The possible role of concentric tube robotics surgery in skull base pathologies has been explored, and the novel use of telesurgery incorporated into robotic neurosurgery is discussed. An endoscopic endonasal transsphenoidal surgical system has also been developed, integrating computational methods to create a presurgical reconstructive model for surgical planning and automating the line of dissection for an enhanced approach to the sphenoid sinus. While surgical robotics for transsphenoidal surgery remain in its nascency, these preliminary findings are promising and suggest a role for robotic pituitary surgery.

Background Machine learning has emerged as a viable asset in the setting of pituitary surgery. In the past decade, the number of machine learning models developed to aid in the diagnosis of pituitary lesions and predict intraoperative and postoperative complications following transsphenoidal surgery has increased exponentially. As computational processing power continues to increase, big data sets continue to expand, and learning algorithms continue to surpass gold standard predictive tools, machine learning will serve to become an important component in improving patient care and outcomes. Methods Relevant studies were identified based on a literature search in PubMed and MEDLINE databases, as well as from other sources including reference lists of published articles. Results Radiomics and artificial neural networks comprise the majority of machine learning–based applications in pituitary surgery. Radiomics serves to quantify specific imaging features, which can then be used to noninvasively identify tumor characteristics and make definitive diagnoses, circumventing presurgical biopsy altogether. Neural networks can be adapted to predict intraoperative changes in visual evoked potentials or cerebral spinal fluid leak. In addition, these algorithms may be combined with others to predict tumor aggressiveness, gross total resection, recurrence and remission, and even total cost burden. Conclusions The field of machine learning is broad, with radiomics and artificial neural networks comprising 2 commonly used supervised learning methods in pituitary surgery. Given the large heterogeneity of pituitary and sellar lesions, the promise of machine learning lies in its ability to identify relationships and patterns that are otherwise hidden from standard statistical methods. While machine learning has great potential as a clinical adjunct during the surgical preplanning process and in predicting complications and outcomes, challenges moving forward include standardization and validation of these paradigms.

Transplantation of autologous mitochondria into ischemic tissue may mitigate injury caused by ischemia and reperfusion. Using murine stroke models of middle cerebral artery occlusion, we demonstrate that it is feasible to deliver viable mitochondria to ischemic brain parenchyma via an intra-arterial route of administration. We also show the beneficial supplemental effects of concurrent focused ultrasound activation of microbubbles, which serves to open the blood-brain barrier without hemorrhagic complications. Following delivery, mitochondria distribute through the stroked hemisphere and integrate into neural and glial cells in the brain parenchyma. Consistent with functional integration in the ischemic tissue, the transplanted mitochondria elevate concentration of adenosine triphosphate in the stroked hemisphere, reduce infarct volume and increase neuronal viability. Our results have implications for the development of interventional strategies after ischemic stroke and suggest a novel potential modality of therapy after mechanical thrombectomy.

Arteriovenous malformation (AVM) presenting with epilepsy significantly impacts patient quality of life, and it should be considered very much a seizure disorder. Although hemorrhage prevention is the primary treatment aim of AVM surgery, seizure control should also be at the forefront of therapeutic management. Several hemodynamic and morphological characteristics of AVM have been identified to be associated with seizure presentation. This includes increased AVM flow, presence of long pial draining vein, venous outflow obstruction, and frontotemporal location, among other aspects. With the advent of high-throughput image processing and quantification methods, new radiographic attributes of AVM-related epilepsy have been identified. With respect to therapy, several treatment approaches are available, including conservative management or interventional modalities; this includes microsurgery, radiosurgery, and embolization or a combination thereof. Many studies, especially in the domain of microsurgery and radiosurgery, evaluate both techniques with respect to seizure outcomes. The advantage of microsurgery lies in superior AVM obliteration rates and swift seizure response. In addition, by incorporating electrophysiological monitoring during AVM resection, adjacent or even remote epileptogenic foci can be identified, leading to extended lesionectomy and improved seizure control. Radiosurgery, despite resulting in reduced AVM obliteration and prolonged time to seizure freedom, avoids the risks of surgery altogether and may provide seizure control through various antiepileptic mechanisms. Embolization continues to be used as an adjuvant for both microsurgery and radiosurgery. In this study, the authors review the latest imaging techniques in characterizing AVM-related epilepsy, in addition to reviewing each treatment modality.

Glioma continues to be a challenging disease process, making up the most common tumor type within the pediatric population. While low-grade gliomas are typically amenable to surgical resection, higher grade gliomas often require additional radiotherapy in conjunction with adjuvant chemotherapy. Molecular profiling of these lesions has led to the development of various pharmacologic and immunologic agents, although these modalities are not without great systemic toxicity. In addition, the molecular biology of adult glioma and pediatric glioma has been shown to differ substantially, making the application of current chemotherapies dubious in children and adolescents. For this reason, therapies with high tumor specificity based on pediatric tumor cell biology that spare healthy tissue are needed. Oncolytic virotherapy serves to fill this niche, as evidenced by renewed interest in this domain of cancer therapy. Initially discovered by chance in the early 20th century, virotherapy has emerged as a viable treatment option. With promising results based on preclinical studies, the authors review several oncolytic viruses, with a focus on molecular mechanism and efficacy of these viruses in tumor cell lines and murine models. In addition, current phase I clinical trials evaluating oncolytic virotherapy in the treatment of pediatric glioma are summarized.

From their origins as cardiovascular research tools, endovascular techniques have evolved to provide a minimally invasive means of diagnosis and therapy for individuals suffering from occlusive artery disease. The techniques were pioneered by William Harvey, whose work set the stage for all subsequent endovascular experiments. These included the bold self-catheterization procedure performed by Werner Forssmann in 1929, which would lead to his dismissal by his superiors, only to regain respect within the medical community in 1956 on receiving the Nobel Prize. Charles Dotter was the first to understand the true potential of endovascular approaches after a chance recanalization that would catapult arterial catheterization first into the cardiovascular surgical arena, then into neurosurgery for intracranial stenoses. Having been meticulously evaluated and compared with open vascular procedures, endovascular neurosurgery has continued to be refined and optimized. Understanding the history and development of these techniques and their applications in neurosurgery is necessary to appreciate the current clinical utility of these procedures, serving to provide the vascular neurosurgeon a greater array of treatment options for patients. Here we explore the major scientific and technological advancements that facilitated the development of the endovascular approach to cerebral revascularization, as well as current indications and ongoing clinical trials.

OBJECTIVEThe goal of this study was to systematically review the outcomes of endoscopic endonasal surgery (EES) for pediatric craniopharyngiomas so as to assess its safety and efficacy.METHODSA systematic literature review was performed using the PubMed and MEDLINE databases for studies published between 1986 and 2019. All studies assessing outcomes following EES for pediatric craniopharyngiomas were included.RESULTSOf the total 48 articles identified in the original literature search, 13 studies were ultimately selected. This includes comparative studies with other surgical approaches, retrospective cohort studies, and case series.CONCLUSIONSEES for pediatric craniopharyngiomas is a safe and efficacious alternative to other surgical approaches. Achieving gross-total resection with minimal complications is feasible with EES and is comparable, if not superior in some cases, to traditional means of resection. Ideally, a randomized controlled trial might be implemented in the future to further elucidate the effectiveness of EES for resection of craniopharyngiomas.

Cortical spreading depression (CSD) is a pathophysiologic phenomenon that describes an expanding wave of depolarization within the cortical gray matter. Originally described over 70 years ago, this spreading depression disrupts neuronal and glial ionic equilibrium, leading to increased energy demands that can cause a metabolic crisis. This results in secondary insult, further perpetuating brain injury and neuronal death. Initially not thought to be of clinical significance, the view of CSD was modified with the advent of intracranial electroencephalography, or electrocorticography. With these improved monitoring techniques, CSD has been identified as a major mechanism by which traumatic brain injury (TBI) imparts its negative sequalae. TBI is a heterogenous disease process that runs the gamut of clinical presentations. This includes concussion, epidural and subdural hematoma, diffuse axonal injury, and subarachnoid hemorrhage. Nonetheless, CSD appears to be frequently occurring among the various types of TBI, thus allowing for the potential development of targeted therapies in an otherwise ill-fated patient cohort. Although a complete understanding of the interplay between CSD and TBI has not yet been achieved, the authors recount the efforts that have been employed over the last several decades in an effort to bridge this gap. In addition, our current understanding of the role neuroimmune cells play in CSD is discussed in the context of TBI. Finally, current therapeutic strategies using CSD as a pharmacologic target are explored with respect to their clinical use in patients with TBI.

The pathogenesis of intracranial aneurysms remains complex and multifactorial. While vascular, genetic, and epidemiological factors play a role, nascent aneurysm formation is believed to be induced by hemodynamic forces. Hemodynamic stresses and vascular insults lead to additional aneurysm and vessel remodeling. Advanced imaging techniques allow us to better define the roles of aneurysm and vessel morphology and hemodynamic parameters, such as wall shear stress, oscillatory shear index, and patterns of flow on aneurysm formation, growth, and rupture. While a complete understanding of the interplay between these hemodynamic variables remains elusive, the authors review the efforts that have been made over the past several decades in an attempt to elucidate the physical and biological interactions that govern aneurysm pathophysiology. Furthermore, the current clinical utility of hemodynamics in predicting aneurysm rupture is discussed.

Enhanced recovery after surgery (ERAS) is an evidence-based approach developed to ameliorate the patient recovery process following surgical procedures. Employing a multimodal, multidisciplinary approach, ERAS implements strategies and treatment paradigms that have been shown to improve patient outcomes, reduce hospital length of stay, and ultimately reduce healthcare costs. With a substantial body of the literature supporting the implementation of ERAS in other surgical specialties, ERAS has only recently made its foray into spine surgery. Despite this, current studies are limited to spinal deformity and degenerative disease, with limited data regarding spinal cord surgery. This is due in part to the complex nature and rarity of spinal cord lesions, making the establishment of a formal ERAS protocol difficult. In developing an ERAS protocol, there must be a consensus on what factors are important to consider and implement. To address this, we reviewed the most recent advances in intramedullary and extramedullary spinal cord surgery in order to identify elements that influence patient outcomes. Using this information, the authors provide evidence-based recommendations with the intent of introducing a framework for future ERAS protocols with respect to treating spinal cord lesions.

OBJECTIVEEnhanced recovery after surgery (ERAS) is a multidimensional approach to improving the care of surgical patients using subspecialty- and procedure-specific evidence-based protocols. The literature provides evidence of the benefits of ERAS implementation, which include expedited functional recovery, decreased postoperative morbidity, reduced costs, and improved subjective patient experience. Although extensively examined in other surgical areas, ERAS principles have been applied to spine surgery only in recent years. The authors examine studies investigating the application of ERAS programs to patients undergoing spine surgery.METHODSThe authors conducted a systematic review of the PubMed and MEDLINE databases up to November 20, 2018.RESULTSTwenty full-text articles were included in the qualitative analysis. The majority of studies were retrospective reviews of nonrandomized data sets or qualitative investigations lacking formal control groups; there was 1 protocol for a future randomized controlled trial. Most studies demonstrated reduced lengths of stay and no increase in rates of readmissions or complications after introduction of an ERAS pathway.CONCLUSIONSThese introductory studies demonstrate the potential of ERAS protocols, when applied to spine procedures, to reduce lengths of stay, accelerate return of function, minimize postoperative pain, and save costs.

While the majority of cerebral revascularization advancements were made in the last century, it is worth noting the humble beginnings of vascular surgery throughout history to appreciate its progression and application to neurovascular pathology in the modern era. Nearly 5000 years of basic human inquiry into the vasculature and its role in neurological disease has resulted in the complex neurosurgical procedures used today to save and improve lives. This paper explores the story of the extracranial-intracranial approach to cerebral revascularization.

Neuroimaging is an indispensable tool in the workup and management of patients with neurological disorders. Arterial spin labeling (ASL) is an imaging modality that permits the examination of blood flow and perfusion without the need for contrast injection. Noninvasive in nature, ASL provides a feasible alternative to existing vascular imaging techniques, including angiography and perfusion imaging. While promising, ASL has yet to be fully incorporated into the diagnosis and management of neurological disorders. This article presents a review of the most recent literature on ASL, with a special focus on its use in moyamoya disease, brain neoplasms, seizures, and migraines and a commentary on recent advances in ASL that make the imaging technique more attractive as a clinically useful tool.

Microsurgical resection of deep-seated cerebral cavernous malformations may result in a high rate of temporary and a lower, but nonetheless significant, rate of permanent disability. Use of trans-sulcal corridors may allow the surgeon to gain access to select deep-seated lesions without injury. Informed consent was obtained from this patient for a minimally invasive trans-sulcal approach to the malformation. This video illustrates the use of a trans-Sylvian, trans-sulcal approach to resect a deep insular/basal ganglia cavernous malformation in a young patient. The use of the neuronavigation is essential for success in these types of operation as this tool limits the surgeon's footprint in eloquent brain. Unlike superficial lesions where the removal of hemosiderin stained brain is possible and often safe, resection of deep-seated lesions requires the surgeon to distinguish between hemosiderin-stained brain and residual cavernous malformation. This task is not simple, and residual cavernous malformation is the most common reason for re-bleed in patients who have undergone surgery. Resection of symptomatic cavernous malformations in deep locations can be performed safely, but outcomes are heavily influenced by proper patient selection and surgeon experience. In patients with multiple cerebral cavernous malformations, such as the one in this case, genetic testing should be performed.

Resection of intrinsic brainstem tumors is fraught with a high risk of morbidity. In select cases, however, complete tumor resection is possible and can result in long-term benefit to the patient. Informed consent for the operation was obtained. In this video, we illustrate the use of a keyhole retrosigmoid craniotomy for microsurgical resection of an exophytic juvenile pilocytic astrocytoma and highlight the nuances of opening the various fissures between the brainstem and the cerebellum to obtain a more direct view of the brainstem, mapping of the brainstem surface to avoid cranial nerve nuclei, use of safe entry zones to minimize injury to critical structures, and microsurgical technique used to operate within the substance of the brainstem. In general, navigation is used to optimize placement of craniotomy and size of bony opening, to delineate the superior to inferior extent of the tumor, and to confirm that the boundary between the tumor and the normal brainstem is reached at the depth. In general, the authors attempt surgical resection of brainstem tumors that are exophytic, have clear boundaries (signal on T1 postcontrast and T2 sequences denote similar tumor boundaries), do not encapsulate the basilar artery, and do not exhibit infiltration of the deep pontine fibers (as is the case with diffuse intrinsic pontine gliomas). In properly selected patients, surgery for brainstem tumor can result in good resection with preservation of neurological function. This patient developed subtle weakness of the face after surgery, which did not improve at 3 mo, but had preserved hearing function and no further neurological deficits.

This video illustrates the case of a patient with familial cerebral cavernous malformation syndrome with a history of multiple symptomatic hemorrhages attributable to a medullary malformation. The patient had swallowing difficulties and gait instability that was progressively worsening. Informed consent was obtained for surgical exploration. The lesion was noted to abut the floor of the fourth ventricle and was approached using a suboccipital craniotomy. Several safe-entry zones on the floor of the fourth ventricle have been described. For lesions that abut the floor, or those that are exophytic, a direct point of entry into the lesion is selected. When possible, the opening into the floor of the fourth ventricle should be placed off midline. The technique of piecemeal resection of the lesion from the brainstem and preservation of normal, hemosiderin-stained brain is presented. Careful patient selection and respect for normal anatomy are of paramount importance in obtaining excellent outcomes in operations within or adjacent to the brainstem. This medullary lesion was resected completely.