Neurological emergencies are time-sensitive conditions in which rapid diagnosis and early intervention critically influence survival and functional outcomes. This review summarizes essential diagnostic strategies for neurosurgeons involved in acute care, guided by the principles of Emergency Neurological Life Support (ENLS). Initial management prioritizes stabilization of the airway, breathing, and circulation, followed by focused neurological assessment, with particular attention to pupillary findings and quantitative monitoring such as the Neurological Pupil index. Laboratory evaluation aims to promptly identify reversible systemic causes, including metabolic disturbances and coagulation abnormalities that directly affect treatment decisions in acute ischemic stroke and intracerebral hemorrhage, particularly in patients receiving anticoagulants. Neuroimaging plays a central role; non-contrast computed tomography (CT) remains the first-line modality, while CT angiography, perfusion imaging, and magnetic resonance imaging (MRI) provide complementary information for therapeutic decision-making. Imaging markers of hematoma expansion and etiological evaluation are essential in hemorrhagic stroke. Electroencephalography (EEG) is crucial for detecting nonconvulsive status epilepticus in patients with unexplained persistent impaired consciousness. Integrating clinical, laboratory, and imaging findings while recognizing common diagnostic pitfalls is essential for optimizing early neurocritical care management.
Endoscopic transsphenoidal surgery has been the most commonly performed neuroendoscopic procedure in Japan since its reimbursement category was introduced in 2012. Although the surgical technique is now largely standardized, perioperative management and operating room setup still vary among institutions. At our center, patients are positioned in a semi-Fowler's posture with the head elevated to reduce venous bleeding from the cavernous sinus, while carefully monitoring the risk of venous air embolism. A slight vertex-up angle facilitates a natural instrument trajectory and is adjusted according to lesion location. Surgery is performed using a four-hand technique, with the assistant controlling the endoscope and coordinating movements with the surgeon, adapting to anatomical constraints and the use of straight or angled endoscopes. We also describe our approach to perioperative glucocorticoid supplementation, postoperative endocrine management for pituitary disorders, and the prevention and treatment of delayed postoperative hyponatremia. Collaboration with otolaryngologists is preferred for postoperative nasal care. These strategies aim to enhance surgical safety, infection control, endocrine stability, and patient comfort while supporting continued advances in endoscopic skull base surgery.
Minimally invasive surgical techniques, including the endoscopic endonasal transmaxillary-pterygoid approach (EETMPA), the endoscopic transorbital approach (ETOA), and the endoscopic keyhole approach (EKA), have recently been applied to the surgical treatment of trigeminal schwannomas. However, criteria for patient selection and technical nuances remain sparsely reported; therefore, we describe these aspects based on our previous work. For patient selection, a sufficient surgical corridor to the tumor from the paranasal sinus must be identified on magnetic resonance imaging to perform EETMPA. To create an adequate working space, wide sphenoidotomy and ethmoidectomy are required, along with removal of the medial and posterior walls of the maxillary sinus and opening of the pterygopalatine fossa. These steps allow access to Meckel's cave through the quadrangular space, formed by the cavernous and petrous internal carotid arteries, the abducens nerve, and V2. During tumor resection, intracapsular dissection is essential to preserve normal trigeminal nerve fibers. Precise patient selection and intracapsular resection may have contributed to the favorable surgical outcomes of EETMPA for non-vestibular schwannoma. With the accumulation of further clinical experience, criteria for selecting EETMPA, ETOA, or EKA are expected to become clearer.
Endocrinological evaluation is essential in neurosurgery for pituitary-hypothalamic disorders and intracranial conditions, such as tumors, trauma, hemorrhagic/ischemic events, inflammatory diseases, and iatrogenic injuries. Appropriate selection and interpretation of hormonal tests influence diagnosis, treatment strategies, perioperative care, and long-term outcomes. Baseline assessments should include measurements of anterior pituitary hormones (ACTH, TSH, GH, LH/FSH, and prolactin) and their corresponding peripheral hormones (cortisol, free thyroxine, IGF-1, and sex steroids). Because adrenal insufficiency is life-threatening, the ACTH-cortisol axis must be prioritized, with thyroid hormone replacement initiated only after adrenal function is confirmed. If baseline tests are inconclusive, dynamic stimulation tests are used to evaluate each axis; however, test selection must consider safety, as some stimulation tests are associated with rare complications, such as pituitary apoplexy, in patients with large Pit-NETs. This review summarizes the practical aspects of endocrine testing that are relevant to neurosurgeons, including typical endocrine profiles in intracranial diseases, indications and pitfalls of stimulation tests, and perioperative monitoring and hormone replacement, in collaboration with endocrinologists.
Spinal surgery is primarily performed to improve neurological function; compared with intracranial surgery, it is rarely conducted to address life-threatening conditions. As the goal of treatment is functional recovery, postoperative complications must be minimized. Appropriate perioperative management is therefore essential, and includes careful preoperative neurological evaluation; postoperative monitoring of neurological, respiratory, and circulatory status; and early detection and management of complications. Several complications of spinal surgery require attention. Firstly, airway obstruction caused by cervical swelling after anterior cervical surgery, postoperative epidural hematoma leading to neurological deterioration, and cerebrospinal fluid (CSF) leakage are the major complications requiring urgent intervention. Cervical spine surgery has several characteristic complications, depending on the surgical approach; for example, anterior procedures may cause airway compromise, esophageal injury, or recurrent laryngeal nerve palsy, whereas posterior procedures are more commonly associated with C5 palsy and surgical site infection. Thoracic spine surgery requires careful postoperative management as the spinal canal is relatively narrow, while the spinal cord is vulnerable to ischemia. In lumbar spine surgery, symptoms primarily involve the cauda equina, while major complications include epidural hematoma, CSF leakage, and surgical site infection. Appropriate perioperative evaluation and prompt management of complications at the spinal level are essential for achieving favorable surgical outcomes.
Cerebral vascular surgery for cerebral arteriovenous malformations (cAVMs) is often challenging due to the diversity of lesions. I describe my treatment policy, embolization techniques, selection of embolic substances, and device choice. Proper use of embolization techniques is critical for safety in cAVM procedures. I use coils, NBCA, and Onyx. NBCA is employed when short-distance, reliable feeder occlusion is required. I prefer microcatheters with good contrast properties that are compatible with coils; for very thin feeders, I select microcatheter with a finer diameter. In cAVM embolization, "how to use" is more important than "what to use." I define the purpose of embolization and select the technique and material for each case.
Transarterial embolization (TAE) of dural arteriovenous fistulas (DAVFs) has evolved significantly following insurance approval of liquid embolic agents such as OnyxTM and Histoacryl® (n-butyl-2-cyanoacrylate[NBCA]). Onyx allows prolonged injection and controlled penetration into the venous side, whereas NBCA offers rapid polymerization and thrombogenicity. The success of TAE depends on the selection of appropriate delivery devices. The ultra-fine microcatheter, DeFrictor® nano, provides superior distal access to small feeders near the shunt point, thereby facilitating effective embolization. In cases where the affected sinus serves as a normal venous drainage route, sinus protection balloon-assisted TAE is useful for achieving both shunt occlusion and preservation of venous function. This technique allows retrograde embolization of multiple feeders through the venous side. Understanding the characteristics of various liquid embolic agents and specialized devices is essential for achieving complete cure and preventing recurrence. This review discusses the latest devices and effective strategies for TAE of DAVFs.
Clinically non-functioning pituitary neuroendocrine tumors (PitNETs), the most common subtype of pituitary tumors, are frequently detected because of mass effects, such as visual impairment and incidental findings. In the World Health Organization classification in 2022, pituitary adenomas have been termed PitNETs, reflecting their biological diversity. This review summarizes the diagnostic evaluations, surgical indications, pathological characteristics, and surgical techniques for non-functioning PitNETs on endoscopic endonasal transsphenoidal surgery (eTSS). Preoperative assessment requires a meticulous endocrine evaluation and detailed magnetic resonance imaging to define tumor extension and invasion, and its relationship with the surrounding neurovascular structures. Surgery is the first-line treatment for symptomatic tumors. Asymptomatic patients with radiological risk factors were selected. Pathologically, non-functioning PitNETs comprise heterogeneous subtypes defined by transcription factors, including gonadotroph, silent corticotroph, and Pit-1 lineage tumors, with some exhibiting aggressive behavior. Technical aspects of eTSS, including intrasellar and extracapsular tumor removal and extended approaches for suprasellar extension, are discussed, highlighting safe and effective tumor resection. Individualized surgical strategies based on tumor characteristics are essential to achieve optimal outcomes.
Endoscopic endonasal transsphenoidal surgery has become a cornerstone of minimally invasive skull base surgery, particularly for pituitary neuroendocrine tumors. Advances in endoscopic visualization, navigation systems, and surgical instruments have enabled safe and effective use of a direct transnasal corridor to the sella and adjacent skull base structures. However, successful execution of this approach requires a precise understanding of nasal and paranasal sinus anatomy, as well as meticulous surgical technique during the nasal and sphenoid phases of the procedure. This chapter describes the basic concepts and step-by-step techniques of the endoscopic endonasal transsphenoidal approach, with a special emphasis on nasal cavity expansion, sphenoid sinus access, and sellar floor opening. Key anatomical landmarks, including the lamellar concept of the ethmoid sinus, the sphenoid sinus natural ostium, and the relationship between the internal carotid artery and surrounding structures, are highlighted to enhance intraoperative orientation and safety. Practical guidance on mucosal incision, septal cartilage preservation, bone removal, and reconstruction strategies to prevent cerebrospinal fluid leakage is also provided. This chapter aims to establish a practical foundation for novice and intermediate surgeons, facilitating a safe transition to more advanced endoscopic skull base procedures through systematic anatomical understanding and standardized surgical techniques.
Recently, the therapeutic outcomes of most patients with functioning pituitary neuroendocrine tumors have significantly improved because of advanced surgical and medical treatments. Surgical progress is due to the evolution of endoscopic techniques, refinement of surgical instruments, and continued technical innovations. The primary therapeutic goal for functioning tumors is endocrine remission, and treatment should be implemented within a comprehensive therapeutic strategy, in which surgery is crucial. Endoscopic endonasal surgery is a microsurgical procedure and its success relies on securing an adequately wide surgical corridor while respecting the nasal cavity. In enclosed, non-invasive, functioning tumors, selective total resection should be pursued, with meticulous identification of the tumor-normal tissue interface, including extracapsular dissection, if feasible. Tumor invasion of the cavernous sinus remains the most significant independent predictor of unfavorable outcomes; however, in some cases, resection of the medial wall may offer a high likelihood of achieving remission. For large invasive tumors, surgery aims to achieve maximal safe debulking and tumor control along with adjuvant medical and/or radiation therapies.
Neuroendoscopic surgery, which allows tumor removal through a narrow surgical corridor, has been increasingly applied to intraventricular tumors. Although this approach is often regarded as minimally invasive, the restricted operative field and proximity to critical deep brain structures necessitate precise surgical manipulation. Periventricular vein injury can result in serious postoperative neurological deficits, underscoring the importance of meticulous dissection and hemostasis. During tumor removal, preservation of venous drainage should be prioritized. Aggressive resection should be avoided when strong adhesion to the veins is encountered. Gentle counterpressure using small cotton patties, combined with irrigation and suction, facilitated safe dissection and effective venous bleeding control. Hemostasis in neuroendoscopic surgery demands patience. The accurate identification of bleeding points is key. Blind coagulation in a blood-filled field should be avoided. Temporary packing with cotton patties can be effective without interrupting surgical workflow. The appropriate use of angled endoscopes and flexible transitions between the dry and wet fields is important for the reliable assessment of residual tumors and hemostasis. Furthermore, careful consideration of surgical instruments and timely conversion to microscopic surgery, when necessary, are critical for minimizing complications. Mastery of these principles can facilitate a safer neuroendoscopic management of intraventricular tumors.
In neurosurgical practice, neurological examinations must be tailored to the disease type and stage, with emphasis on findings most relevant to clinical decision-making. In spinal surgery, neurological assessment plays a crucial role in identifying the precise level and localization of lesions. Accurate evaluation requires systematic assessment of sensory disturbances based on dermatomal distribution, strength testing of key muscles with attention to myotomal innervation, evaluation of deep tendon reflexes, and assessment of bladder and bowel dysfunctions. A structured and focused examination enables clinicians to translate symptoms into accurate lesion localization. This review summarizes the essential components of neurological examinations required to identify spinal lesions and highlights the common pitfalls that may lead to diagnostic errors. Practical strategies to improve diagnostic accuracy are discussed, with particular emphasis on supporting early-career neurosurgeons in developing reliable clinical reasoning skills.
Endoscopic neurosurgery has advanced rapidly over the past three decades and now represents a core minimally invasive approach in modern neurosurgical practice. Despite technical progress, high-certainty evidence has often lagged, partly because outcome variability is driven not only by disease characteristics but also by procedure-specific complexity, surgeon proficiency, learning curves, and institution-dependent factors such as multidisciplinary team structure and perioperative workflows. This study provides a practical framework for building reproducible clinical evidence in endoscopic neurosurgery. We highlight (1) the design of high-quality clinical databases and the deliberate selection of electronic data capture (EDC) platforms to ensure standardization, completeness, auditability, and future reanalysis; (2) team-based infrastructure and governance, including clearly defined roles (e.g., surgeons, ENT collaborators, coordinators, data managers, biostatisticians) and multicenter mechanisms for oversight, data coordination, and formalized data-sharing agreements and quality-control procedures; and (3) analytical strategies for bias control, integrating appropriate statistical testing with survival analysis, multivariable modeling, propensity-based methods, effect size reporting, and learning-curve evaluation. By aligning robust data infrastructure, effective governance, and rigorous analytical methods, endoscopic neurosurgery can progress beyond anecdotal experience toward transparent, reproducible, and generalizable clinical evidence that informs clinical practice, training, and patient safety.
Endoscopic endonasal surgery (EES) has rapidly evolved as a minimally invasive option for ventral posterior fossa lesions, offering a direct midline corridor while avoiding soft-tissue dissection, cerebellar or temporal lobe retraction, and the extensive petrosectomy required in traditional open approaches. However, the indications, anatomical concepts, and technical nuances for safely applying EES to intradural posterior fossa tumors have not yet been standardized. This article presents a practical, stepwise overview of EES for posterior fossa intradural tumors arising around the clivus and ventral brainstem. Based on a three-level clival classification (high, middle, and low clivus defined by Dorello's canal and glossopharyngeal meatus), we outlined the rational selection and execution of transsphenoidal transclival, transpharyngeal transclival, and combined approaches with pituitary transposition. Detailed descriptions of the nasal and skull base exposure, management of high-flow venous and CSF bleeding, and multilayer reconstruction using fascia, rigid buttress, fat graft, and a robust rhinopharyngeal flap. By sharing a reproducible high-resolution strategy grounded in anatomical principles and reconstructive techniques, we aimed to facilitate the safe expansion of EES indications for complex posterior fossa tumors.
Pediatric neuroendoscopic surgery involves a wide range of indications and surgical techniques. Neuroendoscopy has become an essential tool in the management of hydrocephalus in children. Given the heterogeneity of clinical presentations, surgical strategies must be individualized for each case. Additionally, the procedures must consider the fragility of the pediatric brain and emphasize minimally invasive approaches. Such surgeries often involve a high proportion of intraventricular manipulation under continuous irrigation, requiring the appropriate selection of endoscopes and specialized devices suited for such environments. Furthermore, compared with adults, pediatric patients are more prone to complications, including infection, cerebrospinal fluid leakage, and subdural hematoma, necessitating meticulous management during intraoperative cerebrospinal fluid irrigation and wound closure. In this study, we describe the characteristics and key considerations of pediatric neuroendoscopic surgery based on our experience with endoscopic third ventriculostomy (ETV) for noncommunicating hydrocephalus, fenestration of arachnoid cysts, and combined procedures using flexible scopes and rigid ventriculoscopes.
In recent years, titles like "Direct Approach to the Anterior and Lateral Part of the Maxillary Sinus with an Endoscope (DALMA) " have become increasingly common at neurosurgery conferences. However, if DALMA is not performed correctly, external nasal deformities can occur. This section provides information to ensure that DALMA is performed safely and to help prevent complications. Next, the transcribriform approach is addressed. Since this study focuses on this approach, we describe the DRAF procedure and methods for crista galli resection. DRAF surgery, if not performed by surgeons with sufficient experience, may result in insufficient bone resection, thereby complicating surgical exposure. Furthermore, resection of the crista galli significantly improves the anterosuperior view, increases the mobility of the anterior skull base tissues, and ensures adequate working space. Here, we describe the surgical techniques developed or modified by the authors for these three approaches.
Neuroendoscopic intraventricular surgery provides a minimally invasive approach but is inherently challenging, as it is performed within a fragile, three-dimensional ventricular space while relying on a limited two-dimensional endoscopic view. Loss of orientation and subtle technical errors can result in hemorrhage or neural injury. This chapter describes practical strategies for achieving stable and reproducible neuroendoscopic intraventricular surgery, with emphasis on operating room setup, instrumentation, teamwork, and perioperative management. Key principles include aligning the surgeon, patient, and monitor to maintain visuomotor consistency; proactive use of navigation and intraoperative ultrasound to prevent misplacement; and gentle, deliberate manipulation of the vulnerability of ventricular structures. Instrument selection, including rigid scopes, channel-based rigid endoscopic systems, and coagulation-suction devices, is discussed from a safety-oriented perspective. A central emphasis is placed on the role of the assistant, whose responsibilities extend beyond irrigation control ( "water management" ) to include verbal cues and optimization of the surgical environment. Perioperative management, particularly external ventricular drainage (EVD) strategies, postoperative fever, and the role of neuroendoscopic ventricular irrigation in ventriculitis, are also reviewed. Collectively, these concepts highlight that successful neuroendoscopic surgery depends not only on technical proficiency but also on comprehensive surgical design and effective team coordination.
Endovascular treatment for cerebrovascular disease relies on close collaboration among physicians, nurses, and radiologic technologists. A basic understanding of devices is essential for safe and efficient procedures. This review summarizes key concepts of vascular access routes and commonly used devices from the perspective of nurses and technologists working in neuroangiography suites. First, we outline the selection of arterial and venous access, including transfemoral and transradial approaches, with attention to aortic arch variants, upper-extremity arterial anatomy, and patient factors that influence the puncture site and postprocedural care. Next, we describe the structure and roles of introducer sheaths, guiding and intermediate catheters, high-flow microcatheters, and rotating or push-type hemostatic valves, highlighting how coaxial and triaxial systems support device stability. Finally, we review hemostatic devices for access-site closure and practical aspects of contrast injectors, such as pressure limits, contrast dilution, and selection of contrast media to balance image quality with pain reduction and contrast load. The goal of organizing these foundational topics is to support team-based neuroendovascular practice and facilitate communication among all staff involved in these increasingly complex procedures.
The application of endoscopic endonasal surgery is gradually expanding to include lesions located in the midline of the skull base in addition to those in the sella turcica. Meticulous preoperative preparation and prevention and early detection of postoperative complications are important to optimize perioperative management of endoscopic endonasal surgery. Appropriate and careful treatment of any complications is required. Preoperative management predominantly involves imaging and endocrine, visual function, eye movement, and nasal cavity evaluations. Conversely, postoperative management focuses on ensuring pituitary dysfunction, while preventing cerebrospinal fluid leakage, meningitis, and nasal complications. In addition, the method of expansion of the surgical field and skull base reconstruction to reduce postoperative complications are also important. This section explains current perioperative management strategies, focusing on the preoperative and postoperative periods, for endoscopic endonasal surgery for parasellar and midline skull base lesions.
Cerebral vasospasm after aneurysmal subarachnoid hemorrhage (aSAH) is a major cause of delayed cerebral ischemia (DCI) and remains a critical determinant of neurological outcomes. DCI pathophysiology is multifactorial and involves large artery vasospasm and microcirculatory dysfunction, including endothelial injury, microthrombosis, impaired autoregulation, and cortical spreading depolarization. In Japan, pharmacological management has traditionally included fasudil hydrochloride and other agents targeting the vascular tone or platelet aggregation, often combined with strategies to remove subarachnoid blood. The recent approval of clazosentan, a selective endothelin A receptor antagonist, has introduced a new therapeutic approach to prevent vasospasm after aSAH. Clinical trials conducted in Japan have demonstrated that clazosentan reduces vasospasm-related morbidity and mortality, as well as improves clinical outcomes. However, large international trials have shown reductions in angiographic vasospasms without consistent improvements in functional outcomes, highlighting DCI's complex pathophysiology beyond large vessel narrowing. In clinical practice, clazosentan has been associated with favorable outcomes, but requires careful management because of adverse events such as fluid retention and pulmonary complications. Future strategies should focus on optimizing treatment protocols centered on clazosentan and identifying effective combination therapies that target multiple mechanisms underlying DCI.