How I do it: hearing preservation in large vestibular schwannomas using vestibular nerve fiber preservation technique.

BACKGROUND: To improve hearing function after resection of large vestibular schwannomas, we describe a strategy of vestibular-nerve-fiber preservation. Anatomical considerations and stepwise dissection are described. METHOD: Steps include locating the vestibular nerve at the brainstem and identifying a dissection plane between nerve fibers and tumor capsule. Using this plane to mobilize and resect tumor reduced manipulation and maintained vascularity of underlying cochlear and facial nerves. CONCLUSION: Preservation of hearing function is feasible in large vestibular schwannomas with vestibular-nerve-fiber preservation. Reducing manipulation and ischemic injury of underlying cochlear and facial nerves thereby helped facilitate hearing preservation, even in large tumors.

Refining the predictive value of preoperative apparent diffusion coefficient (ADC) by whole-tumor analysis for facial nerve outcomes in vestibular schwannomas.

BACKGROUND: Apparent diffusion coefficient (ADC) in MRI has been shown to correlate with postoperative House-Brackmann (HB) scores in patients with vestibular schwannoma despite limited methodology. To rectify limitations of single region of interest (ROI) sampling, we hypothesize that whole-tumor ADC histogram analysis will refine the predictive value of this preoperative biomarker related to postoperative facial nerve function. METHODS: Of 155 patients who underwent resection of vestibular schwannoma (2014-2020), 125 patients were included with requisite clinical and radiographic data. After volumetric analysis and whole-tumor ADC histogram, regression tree analysis identified ADC cutoff for significant differences in HB grade. Outcomes were extent of resection, facial nerve function, hospital length of stay (LOS), and complications. RESULTS: Regression tree analysis defined three quantitative ADC groups (× 10-6 mm2/s) as high (> 2248.77; HB 1.7), mid (1468.44-2248.77; HB 3.1), and low (< 1468.44; HB 2.3) range (p 0.04). The mid-range ADC group had significantly worse postoperative HB scores and longer hospital LOS. Large tumor volume was independently predictive of lower rates of gross total resection (p <0.0001), higher postoperative HB score (p 0.002), higher rate of complications (p 0.04), and longer LOS (p 0.003). CONCLUSIONS: Whole-tumor histogram yielded a robust regression tree analysis that defined three ADC groups with significantly different facial nerve outcomes. This likely reflects tumor heterogeneity better than solid-tumor ROI sampling. Whole-tumor ADC warrants further study as a useful radiographic biomarker in patients with vestibular schwannoma who are considering surgical resection.

Novel classification of foramen magnum meningiomas predicted by topographic position relative to neurovascular bundle.

PURPOSE: Proximity to critical neurovascular structures can create significant obstacles during surgical resection of foramen magnum meningiomas (FMMs) to the detriment of treatment outcomes. We propose a new classification that defines the tumor's relationship to neurovascular structures and assess correlation with postoperative outcomes. METHODS: In this retrospective review, 41 consecutive patients underwent primary resection of FMMs through a far lateral approach. Groups defined based on tumor-neurovascular bundle configuration included Type 1, bundle ventral to tumor; Type 2a-c, bundle superior, inferior, or splayed, respectively; Type 3, bundle dorsal; and Type 4, nerves and/or vertebral artery encased by tumor. RESULTS: The 41 patients (range 29-81 years old) had maximal tumor diameter averaging 30.1 mm (range 12.7-56 mm). Preoperatively, 17 (41%) patients had cranial nerve (CN) dysfunction, 12 (29%) had motor weakness and/or myelopathy, and 9 (22%) had sensory deficits. Tumor type was relevant to surgical outcomes: specifically, Type 4 demonstrated lower rates of gross total resection (65%) and worse immediate postoperative CN outcomes. Long-term findings showed Types 2, 3, and 4 demonstrated higher rates of permanent cranial neuropathy. Although patients with Type 4 tumors had overall higher ICU and hospital length of stay, there was no difference in tumor configuration and rates of postoperative complications or 30-day readmission. CONCLUSION: The four main types of FMMs in this proposed classification reflected a gradual increase in surgical difficulty and worse outcomes. Further studies are warranted in larger cohorts to confirm its reliability in predicting postoperative outcomes and possibly directing management decisions.

Surgical outcomes in large vestibular schwannomas: should cerebellopontine edema be considered in the grading systems?

PURPOSE: Large (> 3 cm) vestibular schwannomas pose complexity in surgical management because of narrow working corridors and proximity to the cranial nerves, brainstem, and inner ear structures. With current vestibular schwannoma classifications limited in information regarding cerebellopontine edema, our retrospective series examined this radiographic feature relative to clinical outcomes and its possible role in preoperative scoring. METHODS: Of 230 patients who underwent surgical resection of vestibular schwannoma (2014-2020), we identified 107 patients with Koos grades 3 or 4 tumors for radiographic assessment of edema in the middle cerebellar peduncle (MCP), brainstem, or both. Radiographic images were graded and patients grouped into Koos grades 3 or 4 or our proposed grade 5 with edema. Tumor volumes, radiographic features, clinical presentations, and clinical outcomes were evaluated. RESULTS: The 107 patients included 22 patients with grade 3 tumors, 39 with grade 4, and 46 with grade 5. No statistical differences were noted among groups for demographic data or complication rates. Unlike grades 3 and 4 patients, grade 5 patients presented with worse hearing (p < 0.001), larger tumors (p < 0.001), lower rates of gross total resection (GTR), longer hospital stays, and higher rates of balance dysfunction. CONCLUSION: With edema detected in 43% of this cohort, special considerations are warranted for grade 5 vestibular schwannomas given the preoperative findings of worse hearing, lower GTR rates, longer hospital stays, and 96% who pursued postoperative balance therapy. We propose that grade 5 with edema offers a more nuanced interpretation of a radiographic feature that holds relevance to treatment selection and patient outcomes.

Endocrinological outcomes after transcranial resection of tuberculum sellae meningiomas: a systematic review and meta-analysis.

Tuberculum sellae meningiomas (TSMs) arise from the anterior skull base. Endocrine status after TSM resection is an important determinant of quality of life. We sought to better characterize the risk of postoperative endocrinopathy for patients with TSM undergoing open transcranial approach (TCA) microsurgical resection. A systematic review was conducted following MOOSE and PRISMA guidelines. Results were screened against predefined criteria, which included studies evaluating endocrinopathy rates after open transcranial microsurgery for TSM. Outcome incidence was calculated using random-effect meta-analysis of proportions. Eight studies met the inclusion criteria, comprising 406 patients. The average age of the cohort was 52.2 years, and a majority (70%) of the patients were female. The pooled incidence of postoperative transient diabetes insipidus (DI) was 7.5% (95% CI 2.9-12%; p = 0.001; I2 = 75.9%) and permanent DI was 1.6% (95% CI 0.3-2.7%; p = 0.01; I2 = 0%). The pooled rate of postoperative hypopituitarism was 3.6% (95% CI 1.6-5.7%; p < 0.001; I2 = 22.2%), while the incidence of hyperprolactinemia was 1.3% (95% CI 0.1 = 2.6%; p = 0.036; I2 = 8.74%). The incidence of SIADH was 4% in one study but was not included in the meta-analysis. Endocrinopathy after TSM microsurgical resection is rare, but the available studies' poor quality of evidence and inconsistent methodology may reflect that it is underreported in the literature. Nevertheless, clinicians should consider the risk of hormonal impairment and counsel their patients accordingly when selecting a TCA for these lesions.

A two-stage combined anterolateral and endoscopic endonasal approach to the petroclival region: an anatomical study and clinical application.

OBJECT: The pretemporal transcavernous anterior petrosal (PTAP) approach and the combined petrosal (CP) approach have been used to resect petroclival meningiomas (PCMs). In this cadaveric anatomical study, a two-stage combined PTAP and endoscopic endonasal far medial (EEFM) approach (the PTAPE approach) was compared morphometrically to the CP approach. A case study provides a clinical example of using the PTAPE approach to treat a patient with a PCM. The key elements of the approach selection process are outlined. METHODS: Five cadaveric specimens underwent a CP approach and 5 underwent a PTAPE approach. The area of drilled clivus, length of multiple cranial nerves (CNs), and the area of brain stem exposure were measured, reported as means (standard deviations) by group, and compared. RESULTS: The total area of the clivus drilled in the PTAPE group (695.3 [121.7] mm2) was greater than in the CP group (88.7 [17.06] mm2, P < 0.01). Longer segments of CN VI were exposed via the PTAPE than the CP approach (35.6 [9.07] vs. 16.3 [6.02] mm, P < 0.01). CN XII (8.8 [1.06] mm) was exposed only in the PTAPE group. Above the pontomedullary sulcus, the total area of brain stem exposed was greater with the PTAPE than the CP approach (1003.4 [219.5] mm2 vs. 437.6 [83.7] mm2, P < 0.01). Similarly, the total exposure of the medulla was greater after the PTAPE than the CP exposure (240.2 [57.06] mm2 vs. 48.1 [19.9] mm2, P < 0.01). CONCLUSION: A combined open-endoscopic paradigm is proposed for managing large PCMs. This approach incorporates the EEFM approach to address the limitations of the PTAP and the CP approach in a systematic fashion. Understanding the anatomical findings of this study will aid in tailoring surgical approaches to patients with these complex lesions.

Hydroxyapatite cement cranioplasty for reconstruction of translabyrinthine approach: aesthetic results, long-term satisfaction, quality of life, and complications.

BACKGROUND: Translabyrinthine approaches (TLAs) for resection of skull base neoplasms are complex with variable reconstruction techniques. Fat grafts in conjunction with hydroxyapatite bone cement techniques have seldom been described in terms of possible superiority to other skull base reconstruction techniques. We sought to determine the impact of this skull base reconstruction technique on clinical outcomes and patient's satisfaction. METHOD: We performed a retrospective analysis of all patients who underwent translabyrinthine approaches for resection of CPA lesions over a 5-year period. Both post-op objective and subjective markers of reconstruction, as well as postoperative complications, were collected and analyzed. RESULTS: Sixty-nine patients were included, 34 underwent reconstruction with hydroxyapatite and fat (rHAC) and 35 with fat alone (rF). rHAC was associated with fewer cranial wound superficial infection/dehiscence (0% vs 14.3%; p = 0.029) and shorter length of stay (mean ± standard deviation) (6.9 ± 7.4 vs 4.4 ± 3.7 days, p = 0.008). Postoperative subjective characterization of rHAC demonstrated improved satisfaction scores (1.38 ± 0.5 vs 1.83 ± 1; p = 0.049) and fewer reports of post-operative irregularities (11.5% vs 37.5%; p = 0.017). CONCLUSION: The use of hydroxyapatite for cranial reconstruction after translabyrinthine approaches has improved patient satisfaction and decreased cranial defects in our small series. Postoperative complications are consistent with other described methods, but with shorter hospital stay, decreased risk of superficial wound dehiscence/infection, and a perceived superiority in preventing percutaneous post-op CSF leaks.

Long-term disease control and treatment outcomes of stereotactic radiosurgery in cavernous sinus meningiomas.

BACKGROUND: Most of the current knowledge on the clinical effects of stereotactic radiosurgery (SRS) on the treatment of cavernous sinus meningiomas (CSM) is based on series with limited follow-up. However, determining the role of radiation in a tumor with slow disease progression such as CSM necessitates long term follow up. OBJECTIVE: To review and pool metadata in the literature to determine the long-term outcomes of SRS with respect to clinical and radiographic tumor control of CSM. METHODS: A systematic search was conducted following MOOSE guidelines. Results were screened against predefined criteria, which excluded studies with a median follow-up less than 5 years. The incidences of each outcome were calculated using random-effects metanalysis of proportions. RESULTS: Seven studies met the inclusion criteria, comprising 645 patients. The median follow-up was 74 months (range 62-87). Progression-free-survival at 5, 10, and 15 years was 93.4% (95% CI 89.1-96.7%), 84.9% (95% CI 77-91.4%), and 81.3% (95% CI 74-87.7%), respectively. Clinical response to SRS at last follow-up defined as improvement of cranial nerve deficits was found in in 36.4% (95% CI 26.3-47.1%) of patients, while worsening or onset of new cranial nerve deficits was found in 11.5% (95% CI 7.9-15.7%). Radiological regression was found in 57.8% (95% CI 43-71.8%), while tumor progression was found in 8.5% (95% CI 5.2-12.6%). CONCLUSION: SRS achieves excellent disease control and radiographic response in CSM. Although the risk of long-term cranial neuropathies is minimal, it is relatively higher to what has been previously reported in early series with limited follow-up.

The 100 most-cited articles on vestibular schwannoma: historical perspectives, current limitations, and future research directions.

There has been a steady increase of vestibular schwannoma (VS) research in the body of literature. To delineate the most impactful works on VS, a bibliometric analysis is warranted. The Thomson Reuters Web of Sciences database was queried to identify all articles on VS published to June 2020. The articles were sorted in descending order of the number of citations. Titles and abstracts of the top 100 most-cited articles were screened to identify the research area, publication year, author, and country of publication. Our query yielded 6477 research publications. The 100 most-cited articles were cited 15804 times. The most productive decade was the 1990s (40% of the top 100 articles). Twenty-five journals contributed to all included articles. Journal of Neurosurgery contributed most of the articles (20%). Most common contributing country was the USA (60%). "Operative treatment" was the most common research topic (68%), followed by other aspects such as medical management (13%), epidemiology (12%), diagnosis (5%), or translational medicine (2%). The current analysis highlights the importance of the multimodal approach in the study and treatment of VS. While emphasizing the relevance of including highly cited articles in the current education of VS, our results point out the deficiency in certain research areas with high impact in other fields of neuro-oncology, such as translational medicine and molecular epigenetics.

Combined biportal unilateral endoscopic endonasal and endoscopic anterior transmaxillary approach for resection of lesions involving the infratemporal fossa.

BACKGROUND: Approaching tumors involving the infratemporal fossa (ITF) is technically challenging due to the complex relationships between several neurovascular structures and the deep-seated location of these lesions. METHODS: The authors describe in detail a minimally invasive approach to the ITF, consisting on a single-nostril endoscopic endonasal transmaxillary approach aided by an anterior transmaxillary port (EEA-ATMa). Anatomical landmarks and surgical tenets of this approach are highlighted and reviewed with the goal to guarantee successful tumor resection and avoid operative complications. CONCLUSION: The EEA-ATMa is technically feasible and offers excellent surgical exposure to the anterior and lateral aspect of ITF, without the need of transecting the Vidian nerve or performing a wide septectomy.

Impact of vestibular nerve preservation on facial and hearing outcomes in small vestibular schwannoma surgery: a technical feasibility study.

BACKGROUND: Management of small vestibular schwannomas (VSs) remains controversial. When surgery is chosen, the preservation of facial and cochlear nerve function is a priority. In this report, we introduce and evaluate a technique to anatomically preserve the vestibular nerves to minimize manipulation and preserve the function of the facial and cochlear nerves. METHODS: The vestibular nerve preservation technique was prospectively applied to resect small VS tumors in patients with serviceable preoperative hearing (American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) class A or B). Clinical and radiological data were recorded and analyzed. RESULTS: Ten patients met the inclusion criteria. The mean (SD) age was 40.4 (12.5) years. Follow-up ranged from 6 weeks to 2 years. The maximum tumor diameter parallel to the internal auditory canal ranged from 10 to 20 mm (mean, 14.9 (3.1) mm). There were three Koos grade 3 and seven Koos grade 2 tumors. Gross total resection was achieved in all cases. Both the facial and cochlear nerves were anatomically preserved in all cases. Postoperatively, 7 patients (70%) remained in the AAO-HNS class A or B hearing category. None of the patients had new vestibular symptoms, and all had House-Brackmann grade 1 facial function. Nervus intermedius dysfunction was observed in 1 patient preoperatively, which worsened postoperatively. Two patients had new nervus intermedius symptoms postoperatively. CONCLUSION: Improvement of facial nerve and hearing outcomes is feasible through the intentional preservation of the vestibular nerves in the resection of small VSs. Longer follow-up is required to rule out tumor recurrence.

Defining the timing and role of acute postoperative imaging in pituitary adenoma surgery: clinical study.

BACKGROUND: The ideal timing of postoperative imaging after pituitary adenoma surgery has yet to be determined. We reviewed our pituitary database to determine whether timing of routine postoperative imaging has significantly changed patients' clinical course or outcomes. METHODS: Retrospective chart review of patients undergoing resection of pituitary adenoma at our university center between 2012 and 2017 was performed. Timing and indication for postoperative imaging, findings of immediate and delayed postoperative imaging, as well as re-operations and radiosurgery details were recorded. Visual functions such as acuity and visual fields were used as clinical outcome indicators. Statistical analysis was run using Microsoft Excel. RESULTS: Five hundred and nineteen patients were identified; 443 had imaging data in our system and were included in the study. Early (< 90 days) MRIs were obtained in 71 patients and late (≥ 90 days) in 372 patients. We found statistical differences in our demographic groups including larger tumors in the early MRI group (early mean 12.33 cm3, late mean 4.64 cm3, p < 0.001) and higher Knosp grade (p = 0.0006). We found a significant difference in rates of return to the OR (16.9% in the early group and 4.84% in the late group; p < 0.001). There was a significant difference in the rate of residual identified on first postoperative MRI: 52.11% in the early group and 29.57% in the late group (p < 0.001). There was no difference in visual outcomes between the patient cohorts. CONCLUSION: After surgical treatment of pituitary adenoma, MRI obtained before 3 months is associated with higher rates of return to OR but no difference in long-term clinical outcomes. Due to cost efficiency, we argue for a delayed first postoperative MRI. The timing of MRI should also be governed by other factors such as large pituitary macroadenomas or postoperative complications. We recommend a consistent institutional protocol for determining the most cost-effective follow-up of postoperative pituitary patients.

The predictive value of preoperative apparent diffusion coefficient (ADC) for facial nerve outcomes after vestibular schwannoma resection: clinical study.

OBJECT: Diffusion MRI has been used to predict intraoperative consistency of tumors. Apparent diffusion coefficient (ADC) has shown predictive value as an imaging biomarker in many CNS tumors but has not been studied in a large cohort of patients with vestibular schwannoma. In this study, we examine the utility of ADC as a predictive biomarker for intraoperative tumor characteristics and postoperative facial nerve outcome. METHODS: A retrospective review of patients who underwent vestibular schwannoma resection at our institution from 2008 to 2018 yielded 87 patients, of which 72 met inclusion criteria. Operative reports and clinical records were reviewed for clinical data; MRI data were interpreted in a blinded fashion for qualitative and quantitative biomarkers, including tumor ADC. RESULTS: Mean tumor ADC values did not predict intraoperative consistency or adherence (p = 0.63). Adherent tumors were associated with worse facial nerve outcomes (p = 0.003). Regression tree analysis identified 3 ADC categories with statistically different facial nerve outcomes. The categories identified were ADC < 1006.04 × 10-6 mm2/s; ADC 1006.04-1563.93 × 10-6 mm2/s and ADC ≥ 1563.94 × 10-6 mm2/s. Postoperative and final House-Brackmann (HB) scores were significantly higher in the intermediate ADC group (2.3, p = 0.0038). HB outcomes were similar between the group with ADC < 1006.04 × 10-6 mm2/s and ≥ 1563.94 × 10-6 mm2/s (1.3 vs 1.3). CONCLUSIONS: Middle-range preoperative ADC in vestibular schwannoma suggests a less favorable postoperative HB score. Preoperative measurement of ADC in vestibular schwannoma may provide additional information regarding prognostication of facial nerve outcomes.

Surgical management of craniopharyngiomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section.

BACKGROUND AND OBJECTIVE: Craniopharyngiomas are locally aggressive neuroepithelial tumors infiltrating nearby critical neurovascular structures. The majority of published surgical series deal with childhood-onset craniopharyngiomas, while the optimal surgical management for adult-onset tumors remains unclear. The aim of this paper is to summarize the main principles defining the surgical strategy for the management of craniopharyngiomas in adult patients through an extensive systematic literature review in order to formulate a series of recommendations. MATERIAL AND METHODS: The MEDLINE database was systematically reviewed (January 1970-February 2019) to identify pertinent articles dealing with the surgical management of adult-onset craniopharyngiomas. A summary of literature evidence was proposed after discussion within the EANS skull base section. RESULTS: The EANS task force formulated 13 recommendations and 4 suggestions. Treatment of these patients should be performed in tertiary referral centers. The endonasal approach is presently recommended for midline craniopharyngiomas because of the improved GTR and superior endocrinological and visual outcomes. The rate of CSF leak has strongly diminished with the use of the multilayer reconstruction technique. Transcranial approaches are recommended for tumors presenting lateral extensions or purely intraventricular. Independent of the technique, a maximal but hypothalamic-sparing resection should be performed to limit the occurrence of postoperative hypothalamic syndromes and metabolic complications. Similar principles should also be applied for tumor recurrences. Radiotherapy or intracystic agents are alternative treatments when no further surgery is possible. A multidisciplinary long-term follow-up is necessary.

Correction to: Preservation of olfaction in anterior midline skull base meningiomas: a comprehensive approach.

Result is incorrect.

Preservation of olfaction in anterior midline skull base meningiomas: a comprehensive approach.

BACKGROUND: Olfaction is an undervalued sense in neurosurgery. Attempted surgical resection of anterior cranial fossa meningiomas puts the olfactory pathway at risk. Preservation of olfaction may increase the postoperative quality of life. Objective assessment of olfaction may inform clinical decision-making and influence the selection of operative approaches for surgical resection. METHODS: We reviewed all patients who underwent surgical resection for midline anterior skull base meningiomas from July 1, 2014, through December 31, 2017. Patient demographics, tumor size, operative approach, pre- and postoperative deficits, and Simpson grade were collected and analyzed. Postoperative olfaction was assessed by clinical evaluation as well as objective evaluation using the University of Pennsylvania Smell Identification Test (UPSIT). RESULTS: Twenty-eight patients (10 male, 18 female) were included with an average age of 53.8 years (range 27-80 years). Twenty-six patients underwent craniotomy for resection, while 2 patients had endoscopic approaches. Average tumor volume was 402.1 cm3 (6.6-2507.7 cm3). Preoperatively, five patients (17.8%) presented with olfactory impairment. Objectively, 50% of patients (14/28) consented and completed the UPSIT. The average postoperative UPSIT score was 25.8/40 (9/40-38/40). Two patients not identified on clinical assessment alone demonstrated postoperative olfactory deficit on UPSIT (2/14). CONCLUSION: There are limited published studies evaluating olfaction in patients who undergo skull-based approaches for anterior fossa meningiomas. Our series showed the highest olfaction preservation rate (87.5%) using a comprehensive strategy and multitude of surgical approaches based on the olfactory function and tumor characteristics.

Transposition of the paraclival carotid artery: a novel concept of self-retaining vascular retraction during endoscopic endonasal skull base surgery technical report.

BACKGROUND: Fixed retraction of the internal carotid artery (ICA) has previously been described for use during transcranial microscopic surgery. We report the novel use of a self-retaining microvascular retractor for static repositioning and protection of the ICA during expanded endonasal endoscopic approaches to the paramedian skull base. METHODS: The transmaxillary, transpterygoid approach was performed in five cadaver heads (ten sides). The self-retaining microvascular retractor was used to laterally reposition the pterygopalatine fossa contents during exposure of the pterygoid base/plates and the paraclival ICA to expose the petrous apex. Maximum ICA retraction distance was measured in the x-axis for all ten sides. RESULTS: The average horizontal distance of ICA retraction measured at the mid-paraclival segment for all ten sides was 4.75 mm. In all cases, the carotid artery was repositioned without injury to the vessel or disruption of the surrounding neurovascular structures. CONCLUSIONS: Static repositioning of the ICA and other delicate neurovascular structures was effectively performed during endonasal, endoscopic cadaveric surgery of the skull base and has potential merits in live patients.

Unilateral endonasal transcribriform approach with septal transposition for olfactory groove meningioma: can olfaction be preserved?

BACKGROUND: Loss of olfaction has been considered inevitable in endoscopic endonasal resection of olfactory groove meningiomas. Olfaction preservation may be feasible through an endonasal unilateral transcribriform approach, with the option for expansion using septal transposition and contralateral preservation of the olfactory apparatus. METHODS: An expanded unilateral endonasal transcribriform approach with septal transposition was performed in five cadaver heads. The approach was applied in a surgical case of a 24 × 26-mm olfactory groove meningioma originating from the right cribriform plate with partially intact olfaction. RESULTS: The surgical approach offered adequate exposure to the anterior skull base bilaterally. The nasal/septal mucosa was preserved on the contralateral side. Gross total resection of the meningioma was achieved with the successful preservation of the contralateral olfactory apparatus and preoperative olfaction. Six months later, the left nasal cavity showed no disruption of the mucosal lining and the right side was at the appropriate stage of healing for a harvested nasoseptal flap. One year later, the preoperative olfactory function was intact and favorably viewed by the patient. Objective testing of olfaction showed microsomia. CONCLUSIONS: Olfaction preservation may be feasible in the endoscopic endonasal resection of a unilateral olfactory groove meningioma through a unilateral transcribriform approach with septal transposition and preservation of the contralateral olfactory apparatus.