Neurosurgical Management of Patients with Alpha-Gal Syndrome.

Alpha-gal syndrome (AGS) is an immunoglobulin E-mediated hypersensitivity to galatcose-alpha-1,3-galactose (alpha-gal), a carbohydrate compound present in nonprimate mammalian products. Initial exposure to alpha-gal most often occurs through a tick bite, most commonly the lone star tick in the United States. Repeated exposure to alpha-gal may elicit severe allergic reactions, including anaphylaxis. The allergy restricts dietary intake and may significantly impact perioperative risk, as many medications, anesthetics, and intraoperative surgical products utilize bovine or porcine-derived agents, including those containing magnesium stearate, glycerol, and gelatin. Here, we review the perineurosurgical care of two individuals with AGS and highlight pertinent clinical practices and perioperative management of these patients.

Tumor biomechanical stiffness by magnetic resonance elastography predicts surgical outcomes and identifies biomarkers in vestibular schwannoma and meningioma.

Variations in the biomechanical stiffness of brain tumors can not only influence the difficulty of surgical resection but also impact postoperative outcomes. In a prospective, single-blinded study, we utilize pre-operative magnetic resonance elastography (MRE) to predict the stiffness of intracranial tumors intraoperatively and assess the impact of increased tumor stiffness on clinical outcomes following microsurgical resection of vestibular schwannomas (VS) and meningiomas. MRE measurements significantly correlated with intraoperative tumor stiffness and baseline hearing status of VS patients. Additionally, MRE stiffness was elevated in patients that underwent sub-total tumor resection compared to gross total resection and those with worse postoperative facial nerve function. Furthermore, we identify tumor microenvironment biomarkers of increased stiffness, including αSMA + myogenic fibroblasts, CD163 + macrophages, and HABP (hyaluronic acid binding protein). In a human VS cell line, a dose-dependent upregulation of HAS1-3, enzymes responsible for hyaluronan synthesis, was observed following stimulation with TNFα, a proinflammatory cytokine present in VS. Taken together, MRE is an accurate, non-invasive predictor of tumor stiffness in VS and meningiomas. VS with increased stiffness portends worse preoperative hearing and poorer postoperative outcomes. Moreover, inflammation-mediated hyaluronan deposition may lead to increased stiffness.

Matrix metalloproteinase 9: An emerging biomarker for classification of adherent vestibular schwannoma.

Background: The progression of vestibular schwannoma (VS) is intricately linked with interactions between schwannoma cells and the extracellular matrix. Surgical resection of VS is associated with substantial risks as tumors are adherent to the brainstem and cranial nerves. We evaluate the role of matrix metalloproteinase 9 (MMP9) in VS and explore its potential as a biomarker to classify adherent VS. Methods: Transcriptomic analysis of a murine schwannoma allograft model and immunohistochemical analysis of 17 human VS were performed. MMP9 abundance was assessed in mouse and human schwannoma cell lines. Transwell studies were performed to evaluate the effect of MMP9 on schwannoma invasion in vitro. Plasma biomarkers were identified from a multiplexed proteomic analysis in 45 prospective VS patients and validated in primary culture. The therapeutic efficacy of MMP9 inhibition was evaluated in a mouse schwannoma model. Results: MMP9 was the most highly upregulated protease in mouse schwannomas and was significantly enriched in adherent VS, particularly around tumor vasculature. High levels of MMP9 were found in plasma of patients with adherent VS. MMP9 outperformed clinical and radiographic variables to classify adherent VS with outstanding discriminatory ability. Human schwannoma cells secreted MMP9 in response to TNF-α which promoted cellular invasion and adhesion protein expression in vitro. Lastly, MMP9 inhibition decreased mouse schwannoma growth in vivo. Conclusions: We identify MMP9 as a preoperative biomarker to classify adherent VS. MMP9 may represent a new therapeutic target in adherent VS associated with poor surgical outcomes that lack other viable treatment options.

A nomogram to predict long-term facial nerve function after vestibular schwannoma resection: a contemporary multi-institutional study.

OBJECTIVE: The objective of this study was to develop a nomogram to predict long-term facial nerve (FN) function after vestibular schwannoma (VS) resection. METHODS: A retrospective cohort study of two tertiary academic skull base referral centers was performed. Consecutive adults > 18 years of age with sporadic unilateral VS who underwent resection between September 2016 and May 2021 were included. FN function in the immediate postoperative period and at the most recent evaluation was measured. RESULTS: A total of 306 patients (mean age 49 years, 63% female) were included, with a mean follow-up of 18 months. The mean maximum tumor diameter was 19 mm (range 1-50 mm), and 80 (26.1%) tumors were > 25 mm. Overall, 85% of patients showed good immediate postoperative FN function (House-Brackmann [HB] grade I or II) and 89% maintained good FN function at > 12 months of follow-up. An intraoperative FN electromyographic (EMG) response ≥ 100 µV to 0.05 mA of stimulation (OR 18.6, p < 0.001) was the strongest predictor of good HB grade in the immediate postoperative period. EMG response ≥ 100 µV (OR 5.70, p < 0.001), tumor size ≤ 25 mm (OR 3.09, p < 0.05), and better immediate postoperative HB grade (OR 1.48, p = 0.005) predicted good long-term FN function on multivariable analysis. A point-of-care nomogram based on these data predicted long-term FN function with a sensitivity of 89% and specificity of 69%. CONCLUSIONS: Better immediate postoperative HB grade, intraoperative FN EMG response ≥ 100 µV, and tumor size ≤ 25 mm strongly predicted good long-term FN function after VS resection. A point-of-care nomogram based on these variables could serve as a useful tool for postoperative counseling and prognosis of long-term FN recovery.

Advantages and caveats of endoscopic to the infratemporal fossa as isolated and combined techniques.

Objective: Identify the benefits and caveats of combining minimal access approaches to the infratemporal fossa (ITF), such as the endoscopic transnasal, endoscopic transorbital, endoscopic transoral, and endoscopic sublabial transmaxillary approaches to address extensive lesions not amenable to a single approach. The study provides anatomical metrics including area of exposure and degree of surgical freedom. Methods: Five human cadaveric specimens (10 sides) were dissected to expose and methodically analyze the anatomical intricacies of the ITF using the following minimal access approaches: endoscopic transnasal transpterygoid (EETA), endoscopic sublabial transmaxillary, endoscopic transorbital via infraorbital foramen, and endoscopic transoral techniques. Area of exposure at the pterygopalatine fossa and surgical freedom at the ITF were obtained for each approach. Results: The endoscopic sublabial transmaxillary sinus and the combined approach afford a significantly greater exposure than an isolated EETA. The difference in exposure (mean) between the endoscopic sublabial transmaxillary and EETA was 1.62 ± 0.85 cm2 (p < 0.001), and the difference between the combined approach and EETA was 4.25 ± 0.85 cm2 (p < 0.001). Conclusions: Combining minimal access endoscopic approaches to the ITF can provide significantly greater exposure than an isolated EETA; thus, providing enhanced access to address lesions with extensive involvement of the ITF, especially those with superolateral and inferolateral extensions. In addition, some approaches may have an adjunctive role to the resection, such as the endoscopic transoral approach offering the potential for early control of the internal maxillary artery and its branches, some of which may be supplying the tumor in the ITF; or the endoscopic transorbital approach yielding a direct line of sight to the superior ITF and middle cranial fossa. Level of Evidence: NA.

Endoscopic precaruncular medial transorbital and endonasal multiport approaches to the contralateral skull base: a clinicoanatomical study.

OBJECTIVE: Minimally invasive endoscopic endonasal multiport approaches create additional visualization angles to treat skull base pathologies. The sublabial contralateral transmaxillary (CTM) approach and superior eyelid lateral transorbital approach, frequently used nowadays, have been referred to as the "third port" when used alongside the endoscopic endonasal approach (EEA). The endoscopic precaruncular contralateral medial transorbital (cMTO) corridor, on the other hand, is an underrecognized but unique port that has been used to repair CSF rhinorrhea originating from the lateral sphenoid sinus recess. However, no anatomical feasibility studies or clinical experience exists to assess its benefits and demonstrate its potential role in multiport endoscopic access to the other contralateral skull base areas. In this study, the authors explored the application and potential utility of multiport EEA combined with the endoscopic cMTO approach (EEA/cMTO) to three target areas of the contralateral skull base: lateral recess of sphenoid sinus (LRSS), petrous apex (PA) and petroclival region, and retrocarotid clinoidocavernous space (CCS). METHODS: Ten cadaveric specimens (20 sides) were dissected bilaterally under stereotactic navigation guidance to access contralateral LRSS via EEA/cMTO. The PA and petroclival region and retrocarotid CCS were exposed via EEA alone, EEA/cMTO, and EEA combined with the sublabial CTM approach (EEA/CTM). Qualitative and quantitative assessments, including working distance and visualization angle to the PA, were recorded. Clinical application of EEA/cMTO is demonstrated in a lateral sphenoid sinus CSF leak repair. RESULTS: During the qualitative assessment, multiport EEA/cMTO provides superior visualization from a high vantage point and better instrument maneuverability than multiport EEA/CTM for the PA and retrocarotid CCS, while maintaining a similar lateral trajectory. The cMTO approach has significantly shorter working distances to all three target areas compared with the CTM approach and EEA. The mean distances to the LRSS, PA, and retrocarotid CCS were 50.69 ± 4.28 mm (p < 0.05), 67.11 ± 5.05 mm (p < 0.001), and 50.32 ± 3.6 mm (p < 0.001), respectively. The mean visualization angles to the PA obtained by multiport EEA/cMTO and EEA/CTM were 28.4° ± 3.27° and 24.42° ± 5.02° (p < 0.005), respectively. CONCLUSIONS: Multiport EEA/cMTO to the contralateral LRSS offers the advantage of preserving the pterygopalatine fossa contents and the vidian nerve, which are frequently sacrificed during a transpterygoid approach. This approach also offers superior visualization and better instrument maneuverability compared with EEA/CTM for targeting the petroclival region and retrocarotid CCS.

Modified Function-Preserving Endoscopic Endonasal Extracapsular Resection of a Large Orbital Apex Cavernous Hemangioma.

BACKGROUND AND IMPORTANCE: Various invasive oculoplastic procedures are commonly utilized to control the rectus muscles and widen the surgical corridor through the endoscopic endonasal removal of large orbital apex cavernous hemangiomas (OACHs). They require additional transconjunctival incision, rectus muscle insertional retraction, or muscle deinsertion at the globe that might not be safe and lead to prolonged postoperative extraocular muscle dysfunction. In this article, the authors described a modified 3-handed extracapsular technique for the resection of a large OACH without an additional procedure for rectus muscle control. The aim is to achieve a safe gross total tumor removal while minimizing the procedure-related complications. An intraoperative video is included, along with a stepwise cadaveric dissection relevant to the approach. CLINICAL PRESENTATION: A 71-year-old female presented with progressive left-sided blurred vision, binocular diplopia, and mild proptosis. Contrast-enhanced brain MRI revealed a large heterogeneous enhanced inferomedial intraconal mass in the left orbital apex, mostly consistent with cavernous hemangioma. Gross total tumor removal was achieved through a modified 3-handed endoscopic endonasal extracapsular approach. The diplopia was resolved, and significant visual improvement was achieved. Computed tomography scan demonstrated complete tumor removal, and histological examination confirmed the diagnosis. CONCLUSION: Endoscopic endonasal resection of large OACH can be feasibly performed by using a modified 3-handed extracapsular technique through the generous use of Q-tip swab applicators within the natural separation plane around the tumor capsule and a sequential traction-countertraction method. Subsequently, a gross total removal and optimal postoperative functional outcome are attainable through minimal rectus muscle fiber violation and intraconal fat manipulation.

Fully Endoscopic Minimally Invasive Trans-Eyebrow Supraorbital Translaminar Approach to Third Ventricle Craniopharyngiomas: Technical Nuances and Stepwise Illustrative Description.

BACKGROUND: Traditional microsurgical approaches for addressing intraventricular craniopharyngioma provide limited access to the retrochiasmatic area and tumors with significant lateral or rostrocaudal extensions. Extended endoscopic endonasal approaches can effectively overcome many of limitations, yet they require a favorable working angle between the optic chiasm and pituitary gland, as well as the involvement of the third ventricle floor by the tumor. METHODS: Herein, the authors describe the surgical nuances of a keyhole technique for resecting third ventricle craniopharyngiomas via a fully endoscopic minimally invasive trans-eyebrow supraorbital translaminar approach (ESOTLA). A case description detailing the key surgical steps and application of the approach is provided, along with a series of cadaveric photographs to highlight the relevant anatomy and step-by-step dissection process. RESULTS: The patient is a 44-year-old man who presented with polyuria, low urine specific gravity, and panhypopituitarism. Brain magnetic resonance imaging revealed a solid-cystic heterogeneous-enhanced retrochiasmatic mass within the third ventricle, consistent with craniopharyngioma. A 1-stage ESOTLA was indicated based on the narrow pituitary-chiasm angle and the high functional status of the patient. Near-total resection was achieved, and no new postoperative neurologic or endocrine change was observed. Targeted therapy was implemented based on the histologic result, and the most recent surveillance magnetic resonance imaging showed no evidence of the residual tumor. CONCLUSIONS: By combining a keyhole approach with variable-angle endoscopic visualization through a smaller bony and soft tissue exposure, ESOTLA can provide enhanced illumination within the third ventricle, potentially addressing cosmetic concerns and limited exposure area/angle of freedom associated with its conventional microsurgical counterpart.

Customized ventral bony and dural opening in the transplanum/transtuberculum and transclival variants of extended endoscopic endonasal approach to suprasellar craniopharyngiomas: an approach-based stepwise cadaveric dissection and clinical applicability.

BACKGROUND: Optimal initial exposure through an extended endoscopic endonasal approach (EEA) for suprasellar craniopharyngiomas ensures safe and unrestricted surgical access while avoiding overexposure, which may prolong the procedure and increase neurovascular adverse events. METHOD: Here, the authors outline the surgical nuances of a customized bony and dural opening through the transplanum/transtuberculum and transclival variants of the extended EEA to suprasellar craniopharyngiomas based on the tumor-pituitary stalk relationship. A stepwise cadaveric dissection and intraoperative photographs relevant to the approaches are also provided. CONCLUSION: Safe maximal resection of suprasellar craniopharyngiomas through extended EEAs can be feasibly and safely achieved by implementing of tailored ventral exposure.

Management of recurrent giant hemangiopericytoma: illustrative cases.

BACKGROUND: Hemangiopericytoma (HPC) is a rare malignancy accounting for 0.4% of intracranial tumors. HPCs are characterized by local aggressiveness, high rates of recurrence, and a tendency to metastasize to extracranial sites. These features make management of HPCs challenging, often requiring a combination of radical resection and radiation. Given their rarity, optimal treatment algorithms remain undefined. OBSERVATIONS: The authors report a series of four patients who underwent resection of intracranial HPC. Mean age at presentation was 49.3 years. Three patients had reoperation for progression of residual tumor, and one patient was surgically retreated for recurrence. One patient received adjuvant radiotherapy following initial resection, and three patients received adjuvant radiotherapy following resection of recurrent or residual disease. There was one death in the series. Average progression-free survival and overall survival following the index procedure were 32.8 and 82 months, respectively. Progression occurred locally in all patients, with metastatic recurrence in one patient. LESSONS: The current gold-standard treatment for intracranial HPC consists of gross-total resection followed by radiation therapy. This approach allows satisfactory local control; however, given the tendency for these tumors to recur either locally or distally within or outside of the central nervous system, there is a need for salvage therapies to improve long-term outcomes for patients.

Preoperative prescription opioid use as an independent predictor of 90-day mortality and adverse events in craniotomy and craniectomy patients.

OBJECTIVE: A growing body of literature suggests that preoperative opioid exposure is an independent predictor of poor outcomes in surgical patients. No outcomes data exist on preoperative opioid use and craniotomies/craniectomies. The objective of this study was to determine the impact of preoperative opioid use on 90-day adverse events after craniotomy or craniectomy. METHODS: A single-center retrospective cohort study of 2445 patients undergoing a craniotomy/craniectomy between January 1, 2013, and October 1, 2018, was conducted. Baseline demographics, pre- and postoperative opioid use (morphine milligram equivalents [MMEs]), and surgical metrics were recorded. Patients were categorized based on whether they took prescription opioids preoperatively, defined as within 1 month of surgery, or were opioid naive. The outcomes were mortality and adverse events 90 days after craniotomy/craniectomy. RESULTS: Overall, 26.6% of patients composed the preoperative opioid group. The median daily MME intake among this group was 34.6 (IQR 14.1-90) MMEs. Lower employment rates (p < 0.001), uninsured status (p = 0.016), and intravenous drug use (p = 0.006) were associated with preoperative opioid use. Preoperative opioid use was associated with increased venous thromboembolism (p = 0.001), acute kidney injury (p = 0.002), acute respiratory failure (p < 0.001), myocardial infarction (p = 0.002), delirium (p < 0.001), and infection (p < 0.001). Preoperative opioid use was an independent predictor of overall 90-day adverse events (OR 1.643, 95% CI 1.289-2.095; p < 0.001) and 90-day mortality (OR 1.690, 95% CI 1.254-2.277; p < 0.001). CONCLUSIONS: Preoperative opioid use was independently associated with 90-day postoperative adverse events and mortality. Opioid use increases vulnerability in craniotomy/craniectomy patients and necessitates close monitoring to improve outcomes.

Staged Resection of Difficult-to-Treat Intracranial Meningiomas: A Systematic Review of the Indications, Surgical Approaches, and Postoperative Outcomes.

Introduction Meningiomas-the most common extra-axial tumors-are benign, slow-growing dural-based lesions that can involve multiple cranial fossae and can progress insidiously for years until coming to clinical attention secondary to compression of adjacent neurovascular structures. For complex, multicompartmental lesions, multistaged surgeries have been increasingly shown to enhance maximal safe resection while minimizing adverse sequela. Here, we systematically review the extant literature to highlight the merits of staged resection. Methods PubMed, Scopus, and Web of Science databases were queried to identify articles reporting resections of intracranial meningiomas using a multistaged approach, and articles were screened for possible inclusion in a systematic process performed by two authors. Results Of 118 identified studies, 36 describing 169 patients (mean age 42.6 ± 21.3 years) met inclusion/exclusion criteria. Petroclival lesions comprised 57% of cases, with the most common indications for a multistaged approach being large size, close approximation of critical neurovascular structures, minimization of brain retraction, identification and ligation of deep vessels feeding the tumor, and resection of residual tumor found on postoperative imaging. Most second-stage surgeries occurred within 3 months of the index surgery. Few complications were reported and multistaged resections appeared to be well tolerated overall. Conclusions Current literature suggests multistaged approaches for meningioma resection are well-tolerated. However, there is insufficient comparative evidence to draw definitive conclusions about its advantages over an unstaged approach. There are similarly insufficient data to generate an evidence-based decision-making framework for when a staged approach should be employed. This highlights the need for collaborative efforts among skull base surgeons to establish an evidentiary to support the use of staged approaches and to outline those indications that merit such an approach.

Final report of the phase II NEXT/CNS-GCT-4 trial: GemPOx followed by marrow-ablative chemotherapy for recurrent intracranial germ cell tumors.

Background: Patients with relapsed intracranial germinoma can achieve durable remission with standard chemotherapy regimens and/or reirradiation; however, innovative therapies are required for patients with relapsed and/or refractory intracranial nongerminomatous germ cell tumors (NGGCTs) due to their poor prognosis. Improved outcomes have been reported using reinduction chemotherapy to achieve minimal residual disease, followed by marrow-ablative chemotherapy (HDCx) with autologous hematopoietic progenitor cell rescue (AuHPCR). We conducted a phase II trial evaluating the response and toxicity of a 3-drug combination developed for recurrent intracranial germ cell tumors consisting of gemcitabine, paclitaxel, and oxaliplatin (GemPOx). Methods: A total of 9 patients with confirmed relapsed or refractory intracranial GCT were enrolled after signing informed consent, and received at least 2 cycles of GemPOx, of which all but 1 had relapsed or refractory NGGCTs. One patient with progressive disease was found to have pathologically confirmed malignant transformation to pure embryonal rhabdomyosarcoma (without GCT elements), hence was ineligible and not included in the analysis. Patients who experienced sufficient responses proceeded to receive HDCx with AuHPCR. Treatment response was determined based on radiographic tumor assessments and tumor markers. Results: A total of 7 patients achieved sufficient response and proceeded with HDCx and AuHPCR, and 5 subsequently received additional radiotherapy. A total of 2 patients developed progressive disease while receiving GemPOx. Myelosuppression and transaminitis were the most common treatment-related adverse events. With a mean follow-up of 44 months, 4 patients (3 NGGCTs, 1 germinoma) are alive without evidence of disease. Conclusions: GemPOx demonstrates efficacy in facilitating stem cell mobilization, thus facilitating the feasibility of both HDCx and radiotherapy.

Contralateral Nasofrontal Trephination: A Novel Corridor for a "Dual Port" Approach to the Petrous Apex.

BACKGROUND AND OBJECTIVES: Expanded endonasal approaches (EEAs) have proven safe and effective in treating select petrous apex (PA) pathologies. Angled endoscopes and instruments have expanded indications for such approaches; however, the complex neurovascular anatomy surrounding the petrous region remains a significant challenge. This study evaluates the feasibility, anatomic aspects, and limitations of a contralateral nasofrontal trephination (CNT) route as a complementary corridor improving access to the PA. METHODS: Expanded endonasal and CNT approaches to the PA were carried out bilaterally in 15 cadaveric heads with endovascular latex injections. The distance to the PA, angle between instruments through the 2 approach portals, and surgical freedom were measured and compared. RESULTS: Three-dimensional DICOM-based modeling and visualization indicate that the CNT route reduces the distance to the target located within the contralateral PA by an average of 3.33 cm (19%) and affords a significant increase in the angle between instruments (15.60°; 54%). Furthermore, the vertical vector of approach is improved by 28.97° yielding a caudal reach advantage of 2 cm. The area of surgical freedom afforded by 3 different approaches (endonasal, endonasal with an endoscope in CNT portal, and endonasal with an instrument in CNT portal) was compared at 4 points: the dural exit point of the 6th cranial nerve, jugular foramen, foramen lacerum, and petroclival fissure. The mean area of surgical freedom provided by both approaches incorporating the CNT corridor was superior to EEA alone at each of the surgical targets (P = <.001). CONCLUSION: The addition of a CNT portal provides an additional avenue to expand on the classical EEA to the PA. This study provides insight into the anatomic nuances and potential clinical benefits of a dual-port approach to the PA.

Unusual Atrophic Nervus Intermedius in a Patient with Refractory Nervus Intermedius Neuralgia and History of Ipsilateral Sudden-Onset Central Facial Palsy and Sensorineural Hearing Loss: Cadaveric-Clinical Images with Surgical Video.

Nervus intermedius (NI) arises from the superior salivary nucleus, solitary nucleus, and trigeminal tract. It leaves the pons as 1 to 5 roots and travels between the facial and vestibulocochlear nerves before merging with the facial nerve within the internal auditory canal. The mastoid segment of the facial nerve then gives rise to a sensory branch that supplies the posteroinferior wall of the external auditory meatus and inferior pina. This complex pathway renders the nerve susceptible to various pathologies, leading to NI neuralgia. Here, the authors present an unusual intraoperative finding of an atrophic NI in a patient with refractory NI neuralgia and a history of ipsilateral sudden-onset central facial palsy and microvascular decompression for trigeminal neuralgia. The patient underwent NI sectioning via the previous retrosigmoid window and achieved partial ear pain improvement. The gross size of the NI is compared with a cadaveric specimen through stepwise dissection. This case highlights the potential significance of subtle central ischemic events and subsequent atrophy of NI in the pathogenesis of NI neuralgia, as well as the ongoing need to investigate the therapeutic efficacy of nerve sectioning.

Supraorbital Eyebrow Approach for Translamina Terminalis Resection of Third Ventricle Metastasis: 2-Dimensional Operative Video.

Tumors involving the third ventricle are rare, accounting for 0.6%-0.9% of all brain tumors. This deep-seated cavity is surrounded by critical neurovascular structures, making safe surgical resection of lesions in this region challenging. Traditionally, tumors of the third ventricle have been approached through a craniotomy and microsurgical resection.1-4 The supraorbital keyhole approach is a minimally invasive technique that can be used with minimal retraction of the brain and limited craniotomy while establishing a surgical field comparable with what can be achieved using traditional transcranial approaches. In this video, we describe the case of a 54-year-old man who underwent a supraorbital eyebrow approach for translamina terminalis resection of papillary thyroid carcinoma metastasis to the third ventricle. A gross total resection was achieved. The results achieved in our series are comparable with previously published reports of patients who underwent surgical resection of metastatic lesions involving the third ventricle.5-11 The patient consented to the procedure and to the publication of his image.

Management of frontoethmoidal osteoma causing pneumocephalus and cerebrospinal fluid leakage with minimally invasive techniques: illustrative cases.

BACKGROUND: Osteoid osteoma is a common benign bone tumor frequently seen in the frontoethmoid region. However, involvement of the skull base is rare, with few cases previously reported. OBSERVATIONS: The authors report two cases of spontaneous, symptomatic frontoethmoidal osteoma: one presented with neurological deficit secondary to tension pneumocephalus and the other with cerebrospinal fluid leakage. The first case was managed with a transfrontal sinus craniotomy and pneumocephalus decompression with osteoma resection and skull base reconstruction. The second case was managed with a uninaral endoscopic endonasal approach to the anterior skull base with osteoma resection and reconstruction. LESSONS: Given the paucity of cases with associated tension pneumocephalus described in the literature, it was relevant to describe the authors' experience with surgical decision-making and the expected outcomes among patients with this pathology when using minimally invasive techniques.

Morphometric Comparison of Endoscopic Endonasal Transpterygoid and Precaruncular Contralateral Medial Transorbital Approaches to Sphenoid Sinus Lateral Recess.

BACKGROUND AND OBJECTIVES: The endoscopic endonasal transpterygoid approach (TPA), minimally invasive compared with the sublabial transmaxillary and transcranial approaches, still accounts for morbidity in benign lateral recess of sphenoid sinus (LRSS) pathologies. Others have suggested an alternative route to the LRSS, the endoscopic contralateral medial transorbital approach (cMTO). However, no quantitative evidence exists to support the clinical application of this approach. This cadaveric study, in a controlled laboratory setting, provides a morphometric comparison of the TPA and cMTO for accessing the LRSS. The study also details the anatomy and technical nuances for optimizing the cMTO corridor. METHODS: Ten fresh preinjected human cadaveric specimens (20 sides) were dissected with neuronavigation, completing endoscopic cMTO and TPA on each side. Four parameters-working distance to lateral recess, surgical exposure area, angle of attack (AoA), and surgical freedom-were measured for each approach. Relevant osteological measurements in 10 dried human skulls were recorded. RESULTS: The mean distance from the superior margin of the lacrimal sac impression to the inferior margin of the trochlear fossa was 10.29 ± 1.13 mm, and that from the anterior ethmoidal artery foramina to the posterior lacrimal crest was 9.63 ± 1.23 mm. The mean exposure area around the LRSS was significantly higher in TPA (614.09 ± 40.38 mm2) than in cMTO (391.19 ± 59.01 mm2, P = .001). The mean AoA was 9.83° and 10.24° in the cMTO and TPA, respectively, in the craniocaudal direction (P = .529). In the horizontal plane, it was 9.29° and 10.76° (P = .012). There was no significant difference in surgical freedom between the cMTO and TPA (804.61 and 806.05 mm3, respectively; P = .993). CONCLUSION: Although comparatively limited exposure area, the cMTO approach has a similar AoA and surgical freedom as TPA and offers better visualization and ergonomic advantages. cMTO provides a feasible, less morbid, multiport technique for benign sphenoid sinus lateral recess pathologies.

The infundibulochiasmatic angle and the favorability of an endoscopic endonasal approach in type IV craniopharyngioma: illustrative case.

BACKGROUND: Lesions located in the floor of the third ventricle are among the most difficult to access in neurosurgery. The neurovascular structures can limit transcranial exposure, whereas tumor extension into the third ventricle can limit visualization and access. The midline transsphenoidal route is an alternative approach to tumor invading the third ventricle if the tumor is localized at its anterior half and a working space between the optic apparatus and the pituitary infundibulum exists. The authors introduce the "infundibulochiasmatic angle," a valuable measurement supporting the feasibility of the translamina terminalis endoscopic endonasal approach (EEA) for resection of type IV craniopharyngiomas. OBSERVATIONS: Due to a favorable infundibulochiasmatic angle measurement on preoperative magnetic resonance imaging (MRI), an endoscopic endonasal transsellar transtubercular approach was performed to resect a type IV craniopharyngioma. At 2-month follow-up, the patient's neurological exam was unremarkable, with improvement in bitemporal hemianopsia. Postoperative MRI confirmed gross-total tumor resection. LESSONS: The infundibulochiasmatic angle is a radiological tool for evaluating the feasibility of EEA when resecting tumors in the anterior half of the third ventricle. Advantages include reduced brain retraction and excellent rates of resection, with minimal postoperative risks of cerebrospinal fluid leakage and permanent pituitary dysfunction.