Nervus intermedius: Microsurgical and anatomic relationships to the cerebellopontine angle neurovascular complex.

Background: The nervus intermedius (NI) comprises fibers originating from the trigeminal, superior salivary, and solitary tract nuclei, which join the facial nerve (cranial nerve [CN] VII). Neighboring structures include the vestibulocochlear nerve (CN VIII), the anterior inferior cerebellar artery (AICA), and its branches. Microsurgical procedures at the cerebellopontine angle (CPA) benefit from understanding NI anatomy and relationships, especially for the microsurgical treatment of geniculate neuralgia, where the NI is transected.

Coding cerebral bypasses: a proposed nomenclature to better describe bypass constructs and revascularization techniques.

Objective: Bypass surgery has evolved into a complex surgical art with a variety of donor arteries, recipient arteries, interpositional grafts, anastomoses, and suturing techniques. Although innovation in contemporary bypasses has increased, the literal descriptions of these new bypasses have not kept pace. The existing nomenclature that joins donor and recipient arteries with a hyphen is simplistic, underinformative, and in need of improvement.

Prognostic value of the Simpson grading scale in modern meningioma surgery: Barrow Neurological Institute experience.

Objective: Recently, the prognostic value of the Simpson resection grading scale has been called into question for modern meningioma surgery. In this study, the authors analyzed the relationship between Simpson resection grade and meningioma recurrence in their institutional experience.

Methods: This study is a retrospective review of all patients who underwent resection of a WHO grade I intracranial meningioma at the authors' institution from 2007 to 2017.

Tailoring the surgical corridor to the basilar apex in the pretemporal transcavernous approach: morphometric analyses of different neurovascular mobilization maneuvers.

Background: The pretemporal transcavernous approach (PTA) provides optimal exposure and access to the basilar artery (BA); however, the PTA can be invasive when vital neurovascular structures are mobilized. The goal of this study was to evaluate mobilization strategies to tailor approaches to the BA.

Methods: After an orbitozygomatic craniotomy, 10 sides of 5 cadaveric heads were used to assess the surgical access to the BA via the opticocarotid triangle (OCT), carotid-oculomotor triangle (COT), and oculomotor-tentorial triangle (OTT).

Dissection of the Petrosal Presigmoid-Retrolabyrinthine Approach for the Petroclival Region on a Cadaver: 2-Dimensional Operative Video.

Skull base epidermoid tumors, meningiomas, and schwannomas can be accessed by different techniques depending on the location and size of the lesion. Small lesions located anterior to the internal acoustic meatus (IAM) can be accessed via the subtemporal approach, and lesions located posterior to the IAM can be approached via retrosigmoid craniotomy. However, expansive lesions that are located anterior to the IAM and extend posteriorly toward the lower clivus can be accessed via the petrosal approach.

Preoperative embolization versus no embolization for WHO grade I intracranial meningioma: a retrospective matched cohort study.

Objective: The controversy continues over the clinical utility of preoperative embolization for reducing tumor vascularity of intracranial meningiomas prior to resection. Previous studies comparing embolization and nonembolization patients have not controlled for detailed tumor parameters before assessing outcomes.

Methods: The authors reviewed the cases of all patients who underwent resection of a WHO grade I intracranial meningioma at their institution from 2008 to 2016.

Zygomatic-Meatal Perpendicular Projection Lines: Bony Landmarks for Early Identification of the Temporal Horn of the Lateral Ventricle.

Objective: Localization of the temporal horn of the lateral ventricle (TH) may be required during temporal lobe and ambient cistern surgery. Most available anatomic landmarks for TH localization are based on adjacent cortical landmarks that are inherently variable or subtle. This study aimed to localize the anterior tip of the TH relative to adjacent bony landmarks.

Using the Post-Descendens Hypoglossal Nerve in Hypoglossal-Facial Anastomosis: An Anatomic and Histologic Feasibility Study.

Background: Hypoglossal-facial anastomosis (HFA) is a popular facial reanimation technique. Mobilizing the intratemporal segment of the facial nerve and using the post-descendens hypoglossal nerve (ie, the segment distal to the take-off of descendens hypoglossi) have been proposed to improve results. However, no anatomic study has verified the feasibility of this technique.

Exposure of the V1 Segment of the Vertebral Artery: Stepwise Cadaveric Surgical Simulation.

Background: Surgical exposure of the V1 segment of the vertebral artery (V1-VA) at the lower neck may be necessary to address intravascular (atherosclerotic) and extravascular (external compression by neoplastic or degenerative) pathologies. The adjacent anatomy at the lower cervical region is complex and relatively unfamiliar to neurosurgeons compared to that of upper cervical levels. High-quality cadaveric images simulating the surgical approach to V1-VA are important for learning the relevant anatomy.

The side door and front door to the upper retroclival region: a comparative analysis of the open pretemporal and the endoscopic endonasal transcavernous approaches.

Objective: The pretemporal transcavernous approach (PTA) and the endoscopic endonasal transcavernous approach (EETA) are both used to access the retroclival region. A direct quantitative comparison of both approaches has not been made. The authors compared the technical nuances of, and surgical exposure afforded by, each approach and identified the key elements of the approach selection process.

Microsurgical Anatomy of the Meningeal Branch of the Dorsolateral Medullary Plexus.

Background: Meningeal branches originating from intradural arteries may be involved in several diseases such as meningeal tumors and arteriovenous lesions. These "pial-dural" arterial connections have been described for anterior cerebral, posterior cerebral, and cerebellar arteries. However, to the best of our knowledge, meningeal supply originating from the arterial plexus over the dorsolateral aspect of the medulla oblongata (dorsolateral medullary plexus [DLMP]) has not been described.

Survival Outcomes Among Patients With High-Grade Glioma Treated With 5-Aminolevulinic Acid-Guided Surgery: A Systematic Review and Meta-Analysis.

High-grade glioma (HGG) is associated with a dismal prognosis despite significant advances in adjuvant therapies, including chemotherapy, immunotherapy, and radiotherapy. Extent of resection continues to be the most important independent prognosticator of survival. This underlines the significance of increasing gross total resection (GTR) rates by using adjunctive intraoperative modalities to maximize resection with minimal neurological morbidity.

Quantitative analysis of ipsilateral and contralateral supracerebellar infratentorial and occipital transtentorial approaches to the cisternal pulvinar: laboratory anatomical investigation.

Objective: The cisternal pulvinar is a challenging location for neurosurgery. Four approaches for reaching the pulvinar without cortical transgression are the ipsilateral supracerebellar infratentorial (iSCIT), contralateral supracerebellar infratentorial (cSCIT), ipsilateral occipital transtentorial (iOCTT), and contralateral occipital transtentorial/falcine (cOCTF) approaches. This study quantitatively compared these approaches in terms of surgical exposure and maneuverability.

Surgical treatment of falcotentorial meningiomas: a retrospective review of a single-institution experience.

Objective: Meningiomas at the falcotentorial junction represent a rare subgroup of complex meningiomas. Debate remains regarding the appropriate treatment strategy for and optimal surgical approach to these tumors, and surgical outcomes have not been well described in the literature. The authors reviewed their single-institution experience in the management, approach selection, and outcomes for patients with falcotentorial meningiomas.

Styloidogenic Jugular Venous Compression Syndrome: Clinical Features and Case Series.

Background: Styloidogenic jugular venous compression syndrome (SJVCS) is a rare cause of idiopathic intracranial hypertension (IIH).

Objective: To elucidate the pathophysiology and the hemodynamics of SJVCS.

Methods: We conducted a retrospective review of medical records, clinical images, dynamic venography, and manometry for consecutive patients with SJVCS undergoing microsurgical decompression from April 2009 to October 2017.

Contralateral Interhemispheric Transfalcine Approach for Intra-Axial Medial Occipital Lesion: 2-Dimensional Operative Video.

Safe access to intra-axial mesial cortical lesions is challenging. When approached through standard transcortical approaches, normal white matter tracts such as the superior longitudinal fasciculus, corona radiata, and optic radiations may be violated en route to the lesion. Conversely, use of ipsilateral interhemispheric approaches necessitates retraction and manipulation of edematous and friable perilesional tissue.

Retromastoid-transmuscular identification and harvest of the occipital artery during retrosigmoid craniotomy.

Objective: Harvesting the occipital artery (OA) is challenging. The subcutaneous OA is usually found near the superior nuchal line and followed proximally, requiring a large incision and risking damage to the superficially located OA. The authors assessed the anatomical feasibility and safety of exposing the OA through a retromastoid-transmuscular approach.

Fluorescence Image Histology Pattern Transformation Using Image Style Transfer.

Confocal laser endomicroscopy (CLE) allow on-the-fly intraoperative imaging in a discreet field of view, especially for brain tumors, rather than extracting tissue for examination with conventional light microscopy. Fluorescein sodium-driven CLE imaging is more interactive, rapid, and portable than conventional hematoxylin and eosin (H&E)-staining. However, it has several limitations: CLE images may be contaminated with artifacts (motion, red blood cells, noise), and neuropathologists are mainly trained on colorful stained histology slides like H&E while the CLE images are gray.

Efficient harvest of the occipital artery in the retrosigmoid approach: Technical note.

The occipital artery (OA) can be used as a donor artery in many types of bypasses; however, harvesting this artery in the depths of its course is challenging. In order to safely harvest the OA, a large hockey-stick-shaped incision is often used, even when only a retrosigmoid approach is needed for the intracranial procedure. In this article, we describe a detailed technique whereby the OA is harvested via a suboccipital subperiosteal-transperiosteal dissection technique.

Posterior Inferior Cerebellar Artery (PICA) Reanastomosis After Excision of a Ruptured p2-PICA Aneurysm: 2-Dimensional Operative Video.

Posterior inferior cerebellar artery (PICA) aneurysms have an increased tendency towards a fusiform morphology precluding primary clip reconstruction. The management of these complex aneurysms might require cerebral revascularization to preserve flow in a distal PICA territory. This video illustrates a case of a ruptured p2-PICA aneurysm excision followed by a PICA reanastomosis.

The Inferior Nuchal Line as a Simple Landmark for Identifying the Vertebral Artery During the Retrosigmoid Approach.

Background: The V3 segment of the vertebral artery (V3-VA) is at risk during various approaches to the craniovertebral junction. Several landmarks have been defined to identify V3-VA, but these landmarks are not routinely exposed during a retrosigmoid (RS) approach, where musculocutaneous dissection inferiorly towards the foramen magnum can threaten this arterial segment.

Objective: To find a landmark that will identify the V3-VA during the RS approach, and analyze the inferior nuchal line (INL) as this novel landmark.

Anatomical assessment of the digastric branch of the facial nerve as a landmark to localize the extratemporal facial nerve trunk.

Purpose: Localization of the facial nerve trunk (FNT) [i.e., the portion of the facial nerve between the stylomastoid foramen (SMF) and pes anserinus] may be required during various surgical interventions such as parotidectomy and hypoglossal-facial anastomosis.

Travels to the tropics: Deutschtum and Fedor Krause's visits to Brazil.

Fedor Krause, the father of German neurosurgery, traveled to Latin America twice in the final years of his career (in 1920 and 1922). The associations and motivations for his travels to South America and his work there have not been well chronicled. In this paper, based on a review of historical official documents and publications, the authors describe Krause's activities in South America (focusing on Brazil) within the context of the Germanism doctrine and, most importantly, the professional enjoyment Krause reaped from his trips as well as his lasting influence on neurosurgery in South America.

Transcavernous Approach to the Upper Basilar and Retroclival Area-Cadaveric Surgical Simulation Video: 2-Dimensional Operative Video.

The transcavernous approach (TcA) is an extension of the pterional approach that widens access to the central and lateral skull base regions. Through working between the nerves and vascular structures within the cavernous sinus, the TcA enables enhanced exposure of areas and structures including but not limited to the retrosellar area, Meckel's cave, and the basilar trunk. When the basilar apex and retrosellar regions are targeted, the TcA offers a valuable solution to the problem of the restricted space between the neurovascular structures of the central skull base through opening and widening the 2 major triangles of the cavernous sinus roof: the clinoidal and oculomotor triangles.

Anatomical Analysis of the Vagoaccessory Triangle and the Triangles Within: The Suprahypoglossal, Infrahypoglossal, and Hypoglossal-Hypoglossal Triangles.

Background: Rootlets of the lower cranial nerves create a web that limits microsurgical maneuverability in the cerebellomedullary cistern (CMC). The vagoaccessory triangle (VAT) and 2 triangles within it were defined to identify surgical routes to aneurysms of the posterior inferior cerebellar artery (PICA). Dividing the VAT into 2 triangles (suprahypoglossal [SHT] and infrahypoglossal [IHT]), although elegant, oversimplifies CMC anatomy.