Neurological Surgery最新文献

Trigeminal schwannomas are rare, benign tumors with diverse extension patterns along the trigeminal nerve, which significantly influence surgical approach selection. This article presents strategies for selecting optimal approaches based on tumor location, classified into middle, posterior, and extracranial compartments. Commonly used approaches include the anterior transpetrosal, epidural and interdural approaches, and recently introduced minimally invasive techniques, such as the endoscopic endonasal transmaxillary-pterygoid and transorbital approaches. The anatomical accessibility, safety, and feasibility of each technique are discussed. A detailed understanding of the trigeminal nerve's membranous anatomy, including the inner reticular layer and Meckel's cave, enables subcapsular dissection while preserving functional neural structures. This article describes practical techniques, including multilayer skull base reconstruction, venous preservation modifications, and intraoperative neurophysiological monitoring, to mitigate complications, such as venous injury, cerebrospinal fluid leakage, and cranial nerve dysfunction. Additionally, it offers a comprehensive overview of the decision-making and technical nuances essential for safe and effective resection of trigeminal schwannomas in complex skull base regions.

Cerebellopontine angle lesions should be reduced as much as possible while preserving the cranial nerve and brainstem functions. However, because the lesion is located deep and surrounded by various important structures, surgical procedure is difficult to perform, and a surgical strategy is important to avoid complications. Surgical outcomes have dramatically improved with the development of skull bases and microsurgical techniques. The main surgical approaches for cerebellopontine angle lesions include the anterior and posterior combined transpetrosal, anterior transpetrosal, lateral suboccipital, and endoscopic endonasal approaches. With the recent developments in endoscopic keyhole surgery, such as the endoscopic keyhole anterior transpetrosal approach, minimally invasive surgery for skull-base lesions has gradually begun. Here, we describe the preoperative checkpoints, selection of surgical approaches, and surgical techniques for the resection of cerebellopontine angle lesions.

Neurofibromatosis type 2 (NF2), now redefined as NF2-related schwannomatosis (NF2-SWN), is a hereditary tumor syndrome characterized by bilateral vestibular schwannomas, multiple meningiomas, and other central nervous system tumors. The revised diagnostic criteria incorporate genetic testing and consideration of somatic mosaicism, enabling a more accurate and earlier diagnosis. A strong genotype-phenotype correlation has been established: truncating mutations are associated with an earlier onset and severe clinical course, whereas missense or splice-site mutations are often linked to milder phenotypes and better functional outcomes. Immune and molecular profiling have revealed distinct subtypes of vestibular schwannomas and meningiomas, reflecting differences in tumor behavior and therapeutic responses. In young patients presenting with unilateral vestibular schwannoma, clinicians should remain alert to the possibility of NF2-SWN and consider surveillance based on progression and genetic background. Targeted therapies-including bevacizumab, brigatinib, and vascular endothelial growth factor -A vaccines-have shown promise, particularly in refractory cases. Although routine intensive surveillance is not universally required, early genetic screening and long-term follow-ups may benefit select individuals. The comprehensive integration of genetic, pathological, and immunological data is essential for advancing personalized treatment strategies for NF2-SWN.

Recent advancements in reconstructive surgery for facial paralysis following cerebellopontine angle tumor resection have markedly enhanced early and maximal quality of life restoration. Contemporary management paradigms employ multidimensional strategies integrating functional and aesthetic rehabilitation, with hybrid approaches (e.g., static brow lift procedures combined with dynamic free muscle transfers) showing superior outcomes. The timing of referral to a facial paralysis specialist plastic surgeon from the onset of paralysis is critical for optimizing reconstructive outcomes and treatment selection; therefore, early consultation with neurosurgery is strongly recommended.

Hypoglossal schwannomas are extremely rare benign tumors arising from Schwann cells of the 12^th cranial nerve. Surgical management of hypoglossal schwannomas requires detailed knowledge of the anatomy around the lower cerebellopontine angle (CPA), the craniovertebral junction (CVJ), and high cervical regions. If a tumor extends through the hypoglossal canal to the extracranial space, the canal is exposed by drilling the posterior half of the occipital condyle (OC), maintaining craniovertebral stability. Based on our experience and a literature review, we proposed the following modified grading scale to facilitate surgical planning: Type A, intradural tumors; Type B, dumbbell-shaped tumors; Type C, extracranial tumors; and Type D, peripheral tumors. The standard lateral suboccipital approach without opening the foramen magnum (FM) does not always provide adequate operative exposure for intradural type tumors. The transcondylar approach with FM opening and high cervical exposure allows gross total resection of dumbbell-shaped tumors. This specific skull base approach consists of an extended lateral suboccipital craniectomy with partial removal of the OC, which provides a wider view of the lower CPA without excessive cerebellar retraction. Key techniques leading to good outcomes are drilling of the OC, soft tissue dissection around the vertebral artery, and accurate exposure of the anterolateral CVJ.

The lateral suboccipital approach is a fundamental surgical method for accessing the cerebellopontine angle. This article outlines critical aspects, including anatomical landmarks, surgical positioning, and techniques for craniotomy and dural opening, based on practices at our institution. Important landmarks include the mastoid process, asterion, and suboccipital triangle, which contains critical structures such as the vertebral artery. Preoperative three-dimensional computed tomography imaging significantly aids surgical planning through visualizing bone landmarks and venous sinus positioning. Optimal patient positioning, involving careful head flexion and rotation in the park-bench position, is essential to minimize complications such as airway edema. Accurate muscle dissection and careful handling of the mastoid emissary vein are detailed to prevent venous sinus occlusion. Significant complications associated with this procedure include cerebrospinal fluid (CSF) leakage, vertebral artery injury, and venous sinus injury. Strategies for preventing CSF leakage include meticulous dural closure using artificial dura and fat grafts. While rare, vertebral artery injury demands precise handling to prevent severe ischemic complications. Overall, careful anatomical understanding, rigorous preoperative planning, and a meticulous surgical technique are paramount to minimize complications associated with the lateral suboccipital approach.

Neuro-otologic examinations are essential to identify lesion sites in patients with hearing and balance disorders. These tests assess the functions from the peripheral sensory organs to the central auditory and vestibular pathways. They are valuable for evaluating inner ear function and detecting central nervous system involvement. Auditory tests, such as pure-tone audiometry and auditory brainstem response, help localize lesions along the auditory neural pathway. Vestibular function can be assessed using the caloric test, video head impulse test, and vestibular evoked myogenic potentials, which individually evaluate the semicircular canals and otolith organs. Additionally, eye movement recordings using the ENG or VOG during visual stimulation aid in the detection of central vestibular dysfunction. Cerebellopontine angle (CPA) tumors vary in size and extent, from small lesions within the internal auditory canal to large masses compressing the brainstem and cerebellum. Preoperative neuro-otologic assessment provides insight into the extent of the tumor and affected functional areas. This is valuable for understanding the pathophysiology of CPA tumors and contributes to surgical planning and prognosis.

In this study, the application of virtual reality (VR) neurosurgical simulation using 3-dimensional image fusion for preoperative planning of cerebellopontine angle meningiomas is described. Fusion 3-dimensional images are reconstructed from medical imaging modalities, such as computed tomography and magnetic resonance imaging, allowing precise visualization of tumors and adjacent anatomical structures. Surgical planning involves identifying a tumor's location, extent, dural attachment, and the feeding center, in particular, which is a vascular entry point that correlates with the tumor's dural attachment. Early feeding center identification and coagulation can significantly reduce intraoperative bleeding, facilitate tumor resection, and preserve surrounding healthy tissues. A medical device certificated application, namely 'GRID,'was used for preoperative simulation. Two clinical cases showed how VR simulation clarified the tumor's spatial relationship with the cranial nerves and major vessels, enabling safe and effective surgical strategies. The simulation process helped identify critical neurovascular structures, such as the trigeminal nerve, and optimized the craniotomy and approach routes. VR surgical simulation is a valuable tool for improving both operative safety and efficiency and as an educational method for neurosurgical planning and anatomical understanding.

Jugular foramen schwannoma is a rare intracranial tumor, with few opportunities for surgeons to perform tumor excision. This study aimed to provide an outline of jugular foramen schwannoma and our surgical strategy for this tumor. The surgical approach depends on tumor growth patterns with or without extracranial extension. In our institute, a lateral suboccipital retrosigmoid approach is used for intracranial tumors, and mastoidectomy is added for extracranial tumors. For accuracy and safety, neuronavigation and intraoperative neurological monitoring are applied to assist surgery. Herein details of surgical procedures are described. Because functional preservation is prioritized in surgery, intracapsular removal is recommended to prevent adhering cranial nerves from being injured by direct manipulation. Stereotactic radiosurgery has also shown good tumor control. Therefore, the goal of treatment is to achieve good tumor control without deterioration of neurological status during a patient's lifetime using both microsurgery and stereotactic radiosurgery. When considering patient-specific factors such as age and tumor size, less invasive skull base surgery is still necessary to treat jugular foramen schwannoma, for which neurosurgeons require knowledge of the anatomy around the jugular foramen and skills specific to such surgery.

This study assessed the efficacy of combining preoperative three-dimensional (3D) fusion imaging with continuous intraoperative neurophysiological monitoring to enhance the anatomical and functional visualization of cochlear and facial nerves during acoustic neuroma surgery. Data from 282 consecutive patients (2006-2023) were analyzed. In all cases, dorsal cochlear nucleus action potential (DNAP) and facial nerve root evoked electromyography (FREMAP) were continuously monitored. A novel system was implemented for real-time waveform visualization, tracking amplitude trends, and displaying nerve preservation rates, allowing for immediate identification of neural deterioration, causative maneuvers, and responses to surgical interventions. Preoperative 3D fusion imaging was performed in 199 cases, and nerve trajectory visualization was achieved in 65% of these cases. A comprehensive database integrating clinical and intraoperative data was created, and multivariate analyses was performed to identify predictors of postoperative function. Final DNAP and FREMAP preservation rates were significantly associated with hearing and facial nerve outcomes, respectively. Optimal DNAP and FREMAP thresholds, as determined using receiver operating characteristic (ROC) analysis, were ≥ 35.5% and ≥ 58.5%, respectively. These findings support the utility of real-time, continuous neurophysiological monitoring and preoperative imaging in improving nerve preservation. The surgical techniques and monitoring strategies are demonstrated in the accompanying video.