Parasagittal Meningiomas: The Impact of Sinus Opening and Grade of Resection on Clinical Outcome and Recurrence in a Consecutive Series of Patients.

BACKGROUND: Surgical management of parasagittal meningiomas (PMs) remains controversial in the literature. The need to pursue a resection as radical as possible and the high risk of venous injuries contribute to making the sinus opening a widely argued choice. This study aimed to analyze factors affecting the risk of recurrence and to assess clinical outcomes of patients who underwent surgical resection of PMs with conservative or aggressive management of the intrasinusal portion. METHODS: A single-institution retrospective review of all patients with PM surgically treated between January 2013 and March 2021 was conducted. RESULTS: Among 56 patients, the sinus was opened in 32 patients (57%), and a conservative approach was used in 24 patients (43%). The sinus opening was found to be a predictive factor of radical resection (Simpson grade [SG] I-II) (P = 0.007). SG was the only predictive factor of recurrence (P < 0.001). The radical resection group (SG I-II) showed recurrence-free survival at 72 months of about 90% versus 30% in the non-radical resection group (SG III-IV) (log-rank test = 14.21, P < 0.001). Aggressive management of the sinus and radical resection were not found to be related to permanent deficit (P = 0.214 and P = 0.254) or worsening of Karnofsky performance scale score (P = 0.822 and P = 0.933). CONCLUSIONS: Removal of the intrasinusal portion of the tumor using standard procedures is not associated with a higher risk of permanent deficit or worsening of Karnofsky performance scale and reduces the risk of recurrence.

Anatomical landmarks during high-magnification microsurgery for a safe and effective resection of high-grade gliomas: how I do it.

BACKGROUND: Gross total resection, when possible, is the first crucial treatment for high-grade gliomas, as it has been demonstrated to be associated with longer survival. Different intraoperative tools, such as neuronavigation, fluorescent agents, and intra-operative ultrasound, have been developed to help neurosurgeons to extend the resection. METHODS: We describe the high-magnification microsurgery technique used during the first surgical removal for high-grade gliomas. We illustrate the key anatomical "markers" of normal brain parenchyma, which guide the surgery. CONCLUSION: High-magnification microsurgery is an anatomically based approach that allows the identification of key anatomical "markers" of normal brain parenchyma in order to resect high-grade gliomas safely and effectively.

Key role of microsurgical dissections on cadaveric specimens in neurosurgical training: Setting up a new research anatomical laboratory and defining neuroanatomical milestones.

Introduction: Neurosurgery is one of the most complex surgical disciplines where psychomotor skills and deep anatomical and neurological knowledge find their maximum expression. A long period of preparation is necessary to acquire a solid theoretical background and technical skills, improve manual dexterity and visuospatial ability, and try and refine surgical techniques. Moreover, both studying and surgical practice are necessary to deeply understand neuroanatomy, the relationships between structures, and the three-dimensional (3D) orientation that is the core of neurosurgeons' preparation. For all these reasons, a microsurgical neuroanatomy laboratory with human cadaveric specimens results in a unique and irreplaceable training tool that allows the reproduction of patients' positions, 3D anatomy, tissues' consistencies, and step-by-step surgical procedures almost identical to the real ones. Methods: We describe our experience in setting up a new microsurgical neuroanatomy lab (IRCCS Neuromed, Pozzilli, Italy), focusing on the development of training activity programs and microsurgical milestones useful to train the next generation of surgeons. All the required materials and instruments were listed. Results: Six competency levels were designed according to the year of residency, with training exercises and procedures defined for each competency level: (1) soft tissue dissections, bone drilling, and microsurgical suturing; (2) basic craniotomies and neurovascular anatomy; (3) white matter dissection; (4) skull base transcranial approaches; (5) endoscopic approaches; and (6) microanastomosis. A checklist with the milestones was provided. Discussion: Microsurgical dissection of human cadaveric specimens is the optimal way to learn and train on neuroanatomy and neurosurgical procedures before performing them safely in the operating room. We provided a "neurosurgery booklet" with progressive milestones for neurosurgical residents. This step-by-step program may improve the quality of training and guarantee equal skill acquisition across countries. We believe that more efforts should be made to create new microsurgical laboratories, popularize the importance of body donation, and establish a network between universities and laboratories to introduce a compulsory operative training program.

Surgical morbidity of the extradural anterior petrosal approach: the Lariboisière experience.

OBJECTIVE: Concerns about the approach-related morbidity of the extradural anterior petrosal approach (EAPA) have been raised, especially regarding temporal lobe and venous injuries, hearing impairment, facial nerve palsy, cerebrospinal fluid fistula, and seizures. There is lack in the literature of studies with detailed analysis of surgical complications. The authors have presented a large series of patients who were treated with EAPA, focusing on complications and their avoidance. METHODS: The authors carried out a retrospective review of patients who underwent EAPA at their institution between 2012 and 2021. They collected preoperative clinical characteristics, operative reports, operative videos, findings on neuroimaging, histological diagnosis, postoperative course, and clinical status at last follow-up. For pathologies without petrous bone invasion, the amount of petrous apex drilling was calculated and classified as low (< 70% of the volume) or high (≥ 70%). Complications were dichotomized as approach related and resection related. RESULTS: This study included 49 patients: 26 with meningiomas, 10 brainstem cavernomas, 4 chondrosarcomas, 4 chordomas, 2 schwannomas, 1 epidermoid cyst, 1 cholesterol granuloma, and 1 osteoblastoma. The most common approach-related complications were temporal lobe injury (6.1% of patients), seizures (6.1%), pseudomeningocele (6.1%), hearing impairment (4.1%), and dry eye (4.1%). Approach-related complications occurred most commonly in patients with a meningioma (p = 0.02) and Meckel's cave invasion (p = 0.02). Gross-total or near-total resection was correlated with a higher rate of tumor resection-related complications (p = 0.02) but not approach-related complications (p = 0.76). Inferior, lateral, and superior tumoral extension were not correlated with a higher rate of tumor resection-related complications. No correlation was found between high amount of petrous bone drilling and approach- or resection-related complications. CONCLUSIONS: EAPA is a challenging approach that deals with critical neurovascular structures and demands specific skills to be safely performed. Contrary to general belief, its approach-related morbidity seems to be acceptable at dedicated skull base centers. Morbidity can be lowered with careful examination of the preoperative neuroradiological workup, appropriate patient selection, and attention to technical details.

Combined petrosal approach for resection of a large left petroclival meningioma.

Petroclival meningiomas represent the most complex lesions in skull base surgery, being closely related to critical neurovascular structures. The combined petrosal approach allows a wide exposure of the petroclival region and provides multiple angles of attack, limiting brain retraction. The authors present the case of a 54-year-old man with a large left petroclival meningioma responsible for headaches, dysphagia, and trigeminal neuralgia. The lesion was resected using a combined petrosal approach. A progressive improvement of the preoperative symptoms was observed. Postoperative MRI showed a near-total resection of the tumor, along with reexpansion of the brainstem. The video can be found here: https://stream.cadmore.media/r10.3171/2022.1.FOCVID21226.

Endoscopic-Assisted Microsurgical Resection of Right Recurrent Meckel's Cave Meningioma Extended to Cavernous Sinus.

Objective This study was aimed to present the complete removal of a large recurrent Meckel's cave meningioma. Design This study is a case report. Setting The study was conducted at Department of Neurosurgery and Skull Base Laboratory at Lariboisiére Hospital, Paris. Participant A 53-year-old male was presented with a severe V1, V2, and V3 hypoesthesia and pain. He was operated 7 years ago for a right Meckel's cave meningioma with postoperative V1-V2 hypoesthesia. Magnetic resonance imaging (MRI) showed a large tumor recurrence extending into the cavernous sinus (CS), posterior fossa (PF), sphenoid sinus (SS), pterygopalatine (PPF), and infratemporal fossa (ITF; Fig. 1 ). Main Outcome Measures Radiological results and postoperative course were assessed for this study. Results The previous right frontotemporal approach was used. The lateral wall of the orbit, the middle fossa floor and the anterior temporal base were drilled to expose the orbit, PPF, and ITF. Foramen ovale (FO), foramen rotondum (FR), and superior orbital fissure (SOF) were opened. The meningoorbital band was cut and the lateral wall of CS was elevated ( Fig. 2 ). The inferior orbital fissure was opened and tumor removed into the ITF, PPF, and orbit. After entering Meckel's cave from above, tumor was removed from PF. After microsurgical tumor removal, a 45-degree endoscope was used to remove tumor remnant and mucosa into SS. A watertight dural closure with pericranium was performed, reinforced with autologous fat and fibrin glue. Postoperative MRI showed complete tumor resection ( Fig. 1 ). The patient experienced a right-side keratitis that resolved within 10 days and a V3 hypoesthesia that improved at 2 months. Conclusion This surgical case shows how the anatomical knowledge is mandatory in skull base surgery and how the integration of microsurgical and endoscopic-assisted techniques allows to obtain optimal results. The link to the video can be found at: https://youtu.be/qxt_389AdWU .

Lariboisiere Hospital pre-operative surgical checklist to improve safety during transpetrosal approaches.

BACKGROUND: Transpetrosal approaches are technically complex and require a complete understanding of surgical and radiological anatomy. A careful evaluation of pre-operative magnetic resonance imaging and computed tomography scan is mandatory, because anatomical or pathological variations are common and may increase the risk of complications related with the approach. METHODS: Pre-operative characteristics of venous and petrous bone anatomy were analysed and correlated with intraoperative findings, using injected magnetic resonance imaging and thin-slices computed tomography scan. These data regularly checked before each transpetrosal approach were progressively included in the presented checklist. RESULTS: Transpetrosal approaches have been used in 101 patients. Items included in the checklist were petrous bone pneumatization, angle between petrous apex and clivus, dehiscence of petrous carotid artery, dehiscence of geniculate ganglion, distance between superior semicircular canal and middle fossa floor, distance between cochlea and middle fossa floor, sigmoid sinus dominance, transverse sigmoid sinus junction depth to the outer cortical bone, jugular bulb height (high or low), location of the vein of Labbé, characteristics of superior petrosal vein complex. CONCLUSION: The presented checklist provides a systematic scheme of consultation of characteristic of venous and petrous bone anatomy for transpetrosal approaches. In our experience, the use of this checklist reduces the risk of complications related with approach, by minimizing the neglect of crucial information.

The mini-combined transpetrosal approach: an anatomical study and comparison with the combined transpetrosal approach.

BACKGROUND: The combined transpetrosal approach (CTPA) is a versatile technique suitable for challenging skull base pathologies. Despite the advantages provided by a wide surgical exposure, the soft tissue trauma, complex and time-consuming bony work, and cosmetic issues make it far from patient expectations. In this study, the authors describe a less invasive modification of the CTPA, the mini-combined transpetrosal approach (mini-CTPA), and perform a quantitative comparison between these two approaches. METHODS: Five human specimens were used for this study. CTPA was performed on one side and mini-CTPA on the opposite side. The surgical freedom, petroclival and brainstem area of exposure, and maneuverability for 6 anatomical targets, provided by the CTPA and mini-CTPA, were calculated and statistically compared. The bony volumes corresponding to each anterior petrosectomy were also measured and compared. Three clinical cases with an operative video are also reported to illustrate the effectiveness of the approach. RESULTS: The question-mark skin incision done along the muscle attachments permits an optimal cosmetic result. Even though the limited incision, the smaller craniotomy, and the less extensive bone drilling of mini-CTPA provide a smaller area of surgical freedom, the areas of exposure of petroclival region and brainstem were not statistically different between the two approaches. The antero-posterior maneuverability for the oculomotor foramen (OF), Meckel's cave (MC) and the REZ of trigeminal nerve, and the supero-inferior maneuverability for OF, MC, Dorello's canal, and REZ of CN VII are significantly reduced by the smaller opening. The bony volume of anterior petrosectomy resulted similar among the approaches. CONCLUSIONS: The mini-CTPA is an interesting alternative to the CTPA, providing comparable surgical exposure both for petroclival region and for brainstem. Although the lesser soft tissue dissection and bony opening decrease the surgical maneuverability, the mini-CTPA may reduce surgical time, potential approach-related morbidities, and improve cosmetic and functional outcomes for the patients.

A new simple and free tubular device for microscopic transcortical approach to deep-seated lesions: technical note and case example.

BACKGROUND: Surgery for deep-seated brain tumors remains challenging. Transcortical approaches often require brain retraction to ensure an adequate surgical corridor, thus possibly leading to brain damage. Various techniques have been developed to minimize brain retraction such as self-retaining retractors, endoscopic approaches, or tubular retractor systems. Even if they evenly distribute the mechanical pressure over the parenchyma, rigid retractors can also cause some degree of brain damage and have significant disadvantages. We propose here a soft cottonoid retractor for microscopic resection of deep-seated and ventricular lesions. METHODS: Through a small corticectomy, a channel route with a blunt cannula is developed until the lesion is reached. Then, a "balloon-like system" made with a surgical glove is progressively inflated, dilatating the surgical corridor. A mini-tubular device, handmade by suturing a surgical cottonoid, is positioned into the corridor, unfolded, and sutured to the edge of the dura, to prevent it from being progressively expelled from the working channel. This allows a good visualization of the lesion and surrounding structures under the microscope. RESULTS: Advantages of this technique are the softness of the tube walls, the absence of rigid arm to hold the tube, and the possibility for the tube to follow the movements of the instruments and to modify its orientation according to the working area. CONCLUSION: This simple and inexpensive tubular working channel for microscopic transcortical approach is a valuable alternative technique to traditional self-retaining retractor and rigid tube for the microsurgical resection of deep-seated brain tumors.

Hidden intra-meatal CSF fistula related to VP shunt as a cause for fatal tension pneumocephalus after vestibular schwannoma resection.

BACKGROUND: Cerebrospinal fluid (CSF) leak through petrosal air cells is a known complication after drilling the posterior wall of the internal acoustic canal (IAC) for resection of vestibular schwannoma (VS). Whereas mild pneumocephalus is common after retrosigmoid craniotomy, tension pneumocephalus has been rarely documented. OBJECTIVE: To testify a case of fatal tension pneumocephalus after VS resection in a patient with ventriculo-peritoneal (VP) shunt and to propose possible recommendations to limit the risk of this dramatic complication. METHODS: A case of fatal tension pneumocephalus after VS resection in presence of hidden CSF fistula is illustrated with pre- and post-operative images. RESULTS: In the uneventful situation of concomitant post-operative CSF fistula in presence of VP shunt, tension pneumocephalus may occur. The negative pressure created by the shunt system and the presence of osteo-dural defect allow the air to enter and, at the same time, prevent the outflow. CONCLUSION: After VS resection, tension pneumocephalus can occur as a consequence of CSF fistula from petrosal air cells in the presence of functioning VP shunt. Precautions as pre-operative increase to 'virtual-off' the pressure of the valve, subsequences CT scans after surgery and sealing of the petrous air cells are recommended to avoid such as fatal complication.

Intracranial Meningiomas Decrease in Volume on Magnetic Resonance Imaging After Discontinuing Progestin.

BACKGROUND: The behavior of meningiomas under influence of progestin therapy remains unclear. OBJECTIVE: To investigate the relationship between growth kinetics of intracranial meningiomas and usage of the progestin cyproterone acetate (PCA). METHODS: This study prospectively followed 108 women with 262 intracranial meningiomas and documented PCA use. A per-meningioma analysis was conducted. Changes in meningioma volumes over time, and meningioma growth velocities, were measured on magnetic resonance imaging (MRI) after stopping PCA treatment. RESULTS: Mean follow-up time was 30 (standard deviation [SD] 29) mo. Ten (4%) meningiomas were treated surgically at presentation. The other 252 meningiomas were followed after stopping PCA treatment. Overall, followed meningiomas decreased their volumes by 33% on average (SD 28%). A total of 188 (72%) meningiomas decreased, 51 (20%) meningiomas remained stable, and 13 (4%) increased in volume of which 3 (1%) were surgically treated because of radiological progression during follow-up after PCA withdrawal. In total, 239 of 262 (91%) meningiomas regressed or stabilized during follow-up. Subgroup analysis in 7 women with 19 meningiomas with follow-up before and after PCA withdrawal demonstrated that meningioma growth velocity changed statistically significantly (P = .02). Meningiomas grew (average velocity of 0.25 mm3/day) while patients were using PCA and shrank (average velocity of -0.54 mm3/day) after discontinuation of PCA. CONCLUSION: Ninety-one percent of intracranial meningiomas in female patients with long-term PCA use decrease or stabilize on MRI after stopping PCA treatment. Meningioma growth kinetics change significantly from growth during PCA usage to shrinkage after PCA withdrawal.

Pre-surgical fMRI Localization of the Hand Motor Cortex in Brain Tumors: Comparison Between Finger Tapping Task and a New Visual-Triggered Finger Movement Task.

Introduction: Pre-surgical mapping is clinically essential in the surgical management of brain tumors to preserve functions. A common technique to localize eloquent areas is functional magnetic resonance imaging (fMRI). In tumors involving the peri-rolandic regions, the finger tapping task (FTT) is typically administered to delineate the functional activation of hand-knob area. However, its selectivity may be limited. Thus, here, a novel cue-induced fMRI task was tested, the visual-triggered finger movement task (VFMT), aimed at eliciting a more accurate functional cortical mapping of the hand region as compared with FTT. Method: Twenty patients with glioma in the peri-rolandic regions underwent pre-operative mapping performing both FTT and VFMT. The fMRI data were analyzed for surgical procedures. When the craniotomy allowed to expose the motor cortex, the correspondence with intraoperative direct electrical stimulation (DES) was evaluated through sensitivity and specificity (mean sites = 11) calculated as percentage of true-positive and true-negative rates, respectively. Results: Both at group level and at single-subject level, differences among the tasks emerged in the functional representation of the hand-knob. Compared with FTT, VFMT showed a well-localized activation within the hand motor area and a less widespread activation in associative regions. Intraoperative DES confirmed the greater specificity (97%) and sensitivity (100%) of the VFMT in determining motor eloquent areas. Conclusion: The study provides a novel, external-triggered fMRI task for pre-surgical motor mapping. Compared with the traditional FTT, the new VFMT may have potential implications in clinical fMRI and surgical management due to its focal identification of the hand-knob region and good correspondence to intraoperative DES.

The Rostral Mucosa: The Door to Open and Close for Targeted Endoscopic Endonasal Approaches to the Clivus.

BACKGROUND: Extended endoscopic endonasal approaches (EEAs) have progressively widened the armamentarium of skull base surgeons. In order to reduce approach-related morbidity of EEAs and closure techniques, the development of alternative strategies that minimize the resection of normal tissue and alleviate the use of naso-septal flap (NSF) is needed. We report on a novel targeted approach to the clivus, with incision and closure of the mucosa of the rostrum, as the initial and final step of the approach. OBJECTIVE: To present an alternative minimally invasive approach and reconstruction technique for selected clival chordomas. METHODS: Three cases of clival chordomas illustrating this technique are provided, together with an operative video. RESULTS: The mucosa of the rostrum is incised and elevated from the underlying bone, as first step of surgery. Following tumor resection with angled scope and instruments, the mucosa of the sphenoid sinus (SS) is removed and the tumor cavity and SS are filled with abdominal fat. The mucosal incision of the rostrum is then sutured. A hangman knot is prepared outside the nasal cavity and tightened after the first stitch and a running suture is performed. CONCLUSION: We propose, in this preliminary report, a new targeted approach and reconstruction strategy, applying to EEAs the classic concept of skin incision and closure for transcranial approaches. With further development in the instrumentations and visualization tools, this technique may become a valuable minimally invasive endonasal approach for selected lesions.

Tumor Growth Rate as a New Predictor of Progression-Free Survival After Chordoma Surgery.

BACKGROUND: Currently, different postoperative predictors of chordoma recurrence have been identified. Tumor growth rate (TGR) is an image-based calculation that provides quantitative information of tumor's volume changing over time and has been shown to predict progression-free survival (PFS) in other tumor types. OBJECTIVE: To explore the usefulness of TGR as a new preoperative radiological marker for chordoma recurrence. METHODS: A retrospective single-institution study was carried out including patients reflecting these criteria: confirmed diagnosis of chordoma on pathological analysis, no history of previous radiation, and at least 2 preoperative thin-slice magnetic resonance images available to measure TGR. TGR was calculated for all patients, showing the percentage change in tumor size over 1 mo. RESULTS: A total of 32 patients were retained for analysis. Patients with a TGR ≥ 10.12%/m had a statistically significantly lower mean PFS (P < .0001). TGR ≥ 10.12%/m (odds ratio = 26, P = .001) was observed more frequently in recurrent chordoma. In a subgroup analysis, we found that the association of Ki-67 labeling index ≥ 6% and TGR ≥ 10.12%/m was correlated with recurrence (P = .0008). CONCLUSION: TGR may be considered as a preoperative radiological indicator of tumor proliferation and seems to preoperatively identify more aggressive tumors with a higher tendency to recur. Our findings suggest that the therapeutic strategy and clinical-radiological follow-up of patients with chordoma can be adapted also according to this new parameter.

Multilevel Postoperative Cervical Epidural Hematoma: Complete Removal Through Catheter Drainage of the Unexposed Blood Collection.

BACKGROUND: Postoperative spinal epidural hematoma is a rare complication of anterior cervical discectomy and fusion. This condition may rapidly produce severe neurologic deficits, often requiring a prompt surgical decompression. A multilevel extension of the epidural bleeding has been rarely described after anterior cervical procedures. In such cases, the choice of the most suitable surgical approach may be challenging. Herein, we describe an effective surgical decompression of a C2-T1 ventral epidural hematoma following anterior cervical discectomy and fusion at the C5-C6 level. METHODS: By reopening the previous approach, the C5-C6 intersomatic cage was removed and the surgical field inspected for bleeding. After removal of the spinal epidural hematoma at this level, a lumbar external drainage catheter was inserted into the epidural space to perform multiple irrigations with saline solution until the washing fluid was clear. RESULTS: Immediate postoperative cervical computed tomography and magnetic resonance imaging revealed gross total removal of the epidural hematoma and complete decompression of the spinal cord all along the affected tract. Early postoperative neurologic examination revealed mild lower extremity weakness that fully recovered within hours. CONCLUSIONS: Although rare, multilevel epidural hematoma following anterior cervical decompression represents a serious complication. The revision of the previous anterior cervical approach may be considered the first treatment option, allowing to control the primary bleeding site. Catheter irrigation of the epidural space with saline solution may be a useful technique for removal of unexposed residual blood collection, avoiding the need for posterior laminectomy or other unnecessary bone demolition.

Microsurgical anatomy of the amygdaloid body and its connections.

The amygdaloid body is a limbic nuclear complex characterized by connections with the thalamus, the brainstem and the neocortex. The recent advances in functional neurosurgery regarding the treatment of refractory epilepsy and several neuropsychiatric disorders renewed the interest in the study of its functional Neuroanatomy. In this scenario, we felt that a morphological study focused on the amygdaloid body and its connections could improve the understanding of the possible  implications in functional neurosurgery. With this purpose we performed a morfological study using nine formalin-fixed human hemispheres dissected under microscopic magnification by using the fiber dissection technique originally described by Klingler. In our results the  amygdaloid body presents two divergent projection systems named dorsal and ventral amygdalofugal pathways connecting the nuclear complex with the septum and the hypothalamus. Furthermore, the amygdaloid body is connected with the hippocampus through the amygdalo-hippocampal bundle, with the anterolateral temporal cortex through the amygdalo-temporalis fascicle, the anterior commissure and the temporo-pulvinar bundle of Arnold, with the insular cortex through the lateral olfactory stria, with the ambiens gyrus, the para-hippocampal gyrus and the basal forebrain through the cingulum, and with the frontal cortex through the uncinate fascicle. Finally, the amygdaloid body is connected with the brainstem through the medial forebrain bundle. Our description of the topographic anatomy of the amygdaloid body and its connections, hopefully represents a useful tool for clinicians and scientists, both in the scope of application and speculation.

Characteristics and management of hydrocephalus associated with vestibular schwannomas: a systematic review.

Hydrocephalus (HC) can be associated with vestibular schwannoma (VS) at presentation. Although spontaneous resolution of HC after VS removal is reported, first-line treatment is varied including preoperative ventriculoperitoneal (VP) shunt, external ventricular drainage (EVD), or lumbar drainage (LD). We performed a systematic review to clarify optimal management of HC associated with VS at presentation, as well as characteristics of patients with initial and persistent HC after VS removal, and prevalence of HC associated with VS. Fourteen studies were included. Patients were grouped according to the timing of HC treatment. The overall rate of VP shunts was 19.4%. Among patients who received VS removal as first-line treatment, 6.9% underwent permanent shunts. In a subgroup of 132 patients (studies with no-aggregate data), t test analysis for mean tumor size (P = 0.02) and mean CSF protein level (P < 0.001) demonstrated statistically significant differences between patients with resolved HC (3.48 cm and 201 mg/dL) and patients with persistent HC (2.46 cm and 76.8 mg/dL) after VS resection. Transient treatment of HC using EVD or LD further resolved the HC in 87.5% and 82.9% of patients, respectively, before and after VS removal. The overall prevalence of HC associated with VS in a population of 2336 patients was 9.3%. Schwannoma removal as first-line treatment is justified by its low rate of persistent HC requiring VP shunt (roughly 7%). Patients with smaller VS and lower CSF proteins present higher risk of persistent HC after schwannoma removal. Temporary treatment of HC contributes to its resolution, both before and after VS removal.

Extreme Lateral Supracerebellar Infratentorial Approach: Surgical Anatomy and Review of the Literature.

OBJECTIVE: The extreme lateral supracerebellar infratentorial (ELSI) approach has the potential to access several distinct anatomical regions that are otherwise difficult to reach. We have illustrated the surgical anatomy through cadaveric dissections and provided an extensive review of the literature to highlight the versatility of this approach, its limits, and comparisons with alternative approaches. METHODS: The surgical anatomy of the ELSI has been described using 1 adult-injected cadaveric head. Formalized noninjected brain specimens were also dissected to describe the brain parenchymal anatomy of the region. An extensive review of the literature was performed according to each targeted anatomical region. Illustrative cases are also presented. RESULTS: The ELSI approach allows for wide exposure of the middle and posterolateral incisural spaces with direct access to centrally located intra-axial structures such as the splenium, pulvinar, brainstem, and mesial temporal lobe. In addition, for skull base extra-axial tumors such as petroclival meningiomas, the ELSI approach represents a rapid and adequate method of access without the use of extensive skull base approaches. CONCLUSIONS: The ELSI approach represents one of the most versatile approaches with respect to its ability to address several anatomical regions centered at the posterior and middle incisural spaces. For intra-axial pathologies, the approach allows for access to the central core of the brain with several advantages compared with alternate approaches that frequently involve significant brain retraction and cortical incisions. In specific cases of skull base lesions, the ELSI approach is an elegant alternative to traditionally used skull base approaches, thereby avoiding approach-related morbidity.

The Current State of Radiomics for Meningiomas: Promises and Challenges.

Meningiomas are the most common primary tumors of the central nervous system. Given the fact that the majority of meningiomas are benign, the preoperative risk stratification and treatment strategy decision-making highly rely on the conventional subjective radiologic evaluation. However, this traditional diagnostic and treatment modality may not be effective in patients with aggressive-growing tumors or symptomatic patients with potential risk of recurrence after surgical resection or radiotherapy, as this passive "wait and see" strategy could miss the optimal opportunity of intervention. Radiomics, a new rising discipline, translates high-dimensional image information into abundant mathematical data by multiple computational algorithms. It provides an objective and quantitative approach to interpret the imaging data, rather than the subjective and qualitative interpretation from relatively limited human visual observation. In fact, the enormous amount of information generated by radiomics analyses provides radiological to histopathological tumor information, which are visually imperceptible, and offers technological basis to its applications amid diagnosis, treatment, and prognosis. Here, we review the latest advancements of radiomics and its applications in the prediction of the pathological grade, pathological subtype, recurrence possibility, and differential diagnosis of meningiomas, and the potential and challenges in general clinical applications. In this review, we highlight the generalization of shared radiomic features among different studies and compare different performances of popular algorithms. At last, we discuss several possible aspects of challenges and future directions in the development of radiomic applications in meningiomas.