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Even though intracranial meningiomas commonly invade the optic canals, true optic nerve sheath meningiomas are extremely rare. They are insidious lesions that frequently grow in 4 stages, leading to progressive visual loss.1-4 Frequently, management includes observation for asymptomatic patients, and fractioned stereotactic radiotherapy with progressive visual loss.1,3 However, surgery is avoided due to the risk of perioperative visual loss.2-4 However, many of these cases present in the early stage of tumor growth, where an arachnoidal plane is still present, and vision can be saved by microsurgical tumor resection.2 Here we present the case of a 33-yr-old female presenting with a 3-wk history of blurred vision. Neuroimaging depicted an enhancing lesion along both optic nerves consistent with bilateral optic nerve sheath meningioma. Neuroophthalmological examination showed inferior cut of visual field bilaterally, more extensive on the left eye. Acuity was 20/20 on both eyes. Microsurgical resection of the tumor was performed through left supraorbital craniotomy, with the goal of eliminating intracranial extension and stabilizing visual function.5 The optic canal was unroofed with diamond bit drill under copious irrigation. A remarkable improvement of her visual field was observed with maintenance of acuity at 20/20 on follow-up. As the patient is attempting pregnancy, she is closely monitored without radiation. Surgery can be offered as a primary treatment of optic nerve sheath meningiomas, especially in early stages, with likely preservation and, in some cases, improvement of visual function.6 The patient consented to the procedure and the use of image. Images at 1:46 and 3:48 reprinted from Al-Mefty O, Operative Atlas of Meningiomas. 1998: Raven Press; Philadelphia, PA, with permission from LWW. Image at 2:57 reprinted from Rassi et al2; © Anil Can, 2018, used with permission. Image at 9:27 in public domain/age., (© Congress of Neurological Surgeons 2021.)

Background: Traditional treatment options for optic nerve sheath meningiomas (ONSMs) include observation, surgery, and radiotherapy, but to date none of these has become the clear treatment of choice., Objective: To evaluate the effectiveness and safety of multisession radiosurgery for ONSMs., Methods: From May 2004 to June 2008, 21 patients with ONSMs were treated by radiosurgery using the frameless CyberKnife system. Patient age ranged from 36 to 73 years (mean, 54 years). All patients were treated using multisession radiosurgery, with 5 fractions of 5 Gy each to a total dose of 25 Gy prescribed to the 75% to 85% isodose line. Patients were evaluated for tumor growth control and visual function., Results: The median pretreatment tumor volume was 2.8 mL (range, 0.3-23 mL). The mean follow-up was 30 months (range, 11-68 months). All patients tolerated treatment well, with only 1 patient in whom a mild optic neuropathy developed (which remitted after systemic steroid therapy). No other acute or late radiation-induced toxicities were observed. No patients showed ONSM progression on follow-up magnetic resonance imaging. Two patients (10%) had a partial response. No patients had worsening of visual function; visual function was stable in 65% and improved in 35% of patients., Conclusion: Multisession radiosurgery for ONSMs was found to be safe and effective. The preliminary results from this study, in terms of growth control, visual function improvement, and toxicity, are quite promising. Further investigations are warranted.

Background and Importance: Langerhans cell histiocytosis (LCH) is an uncommon disease, usually affecting the cranium and peripheral bones. We present a rare case of isolated optic chiasm involvement by LCH to highlight the importance of considering LCH in the differential diagnosis of optic chiasm lesions., Clinical Presentation: A 71-year-old woman presented with a 6-week history of worsening peripheral vision, headaches, weakness, cold sensitivity, and fatigue. She was found to have dense bitemporal hemianopsia. Magnetic resonance imaging revealed a 2-cm lesion, contrast enhancing on T1 and bright on T2 signal, involving the optic chiasm but not the pituitary gland. Preoperative considerations included optic nerve glioma, choristoma of the stalk, sarcoid, hypothalamic glioma, and Langerhans cell histiocytosis. The patient underwent a right subfrontal craniotomy for biopsy of the lesion. The optic chiasm was grossly enlarged with no tissue external to the chiasm. A midline incision was made in the lamina terminalis, and multiple biopsies were taken of firm fibrous material. Histologically, the tumor was characteristic for LCH and included a mixture of histiocytes with features of Langerhans cells, eosinophils, small lymphocytes, macrophages, neutrophils, and plasma cells., Conclusion: LCH is a rare disease, generally affecting bone, skin, lymph nodes, and in more severe cases, visceral organs. LCH involving the optic pathways is a rare condition that should be included in the differential for adults with mass lesions involving the orbit, eye, optic nerve, or chiasm. Future clinical and basic science research is needed to better understand LCH, its molecular origin, and its growth pattern.

We present an overview of the history, development, technological advancements, current application, and future trends of cranial endoscopy. Neuroendoscopy provides a safe and effective management modality for the treatment of a variety of intracranial disorders, either tumoral or non-tumoral, congenital, developmental, and degenerative, and its knowledge, indications, and limits are fundamental for the armamentarium of the modern neurosurgeon.

Objective: Many approaches have been recommended for the surgical treatment of anterior and middle cranial fossa lesions. The frontobasal approach and its many modifications have been proposed and developed for such situated lesions. An alternative approach is the frontolateral craniotomy through a supraciliary skin incision., Methods: This minimally invasive technique, a 2.5 x 3.0 cm craniotomy, just above the eyebrow through a supraciliary incision, is a simple but elegant modification of the traditional approach to the anterior cranial fossa., Results: A step-by-step description of the approach is offered in this report to facilitate a clear understanding of the lesions treatable with this minimally invasive technique., Conclusion: The supraciliary frontolateral keyhole craniotomy is a minimally invasive cosmetic approach that provides excellent exposure to a variety of intracranial lesions. This approach cannot be used for all intracranial pathologies, but is recommended for many anterior and middle cranial fossa lesions.

Objective: Pilocytic astrocytomas (PA) are Grade I brain tumors characterized by an excellent prognosis. In some cases, however, the patient has a bad outcome. The aim of our study was to search for the clinicopathological factors underlying the prognosis for patients with this disease., Methods: We reviewed the clinical, neuroradiological, and histopathological features of 80 PAs (33 cerebellar, 18 optochiasmatic, 16 brainstem, 7 spinal cord, 3 thalamic, 2 optic nerve, and 1 hemispheric) in pediatric patients., Results: Pathological examination revealed 58 classic PAs and 20 pilomyxoid astrocytomas, which are a histological variant of PAs. Two cases remained unclassified. The mean overall follow-up period was 58 months, the 5-year progression-free survival rate was 75%, and the 5-year survival rates were 100 and 92% after total and partial removal. Univariate statistical analysis revealed that partial resection, optochiasmatic PA localization, and pilomyxoid variant were associated with a worse prognosis, but the latter two parameters were too closely related to the extent of resection to be independent prognostic factors in multivariate analysis. Among the patients who underwent partial surgical removal, only invasion of the surrounding structures was related to prognosis., Conclusion: PAs are benign tumors, but some clinicopathological factors, such as partial resection, optochiasmatic location, invasion of surrounding structures, and the pilomyxoid variant, have a worse prognosis.

Objective: Surgical strategies and results for 50 patients with meningiomas involving the optic nerves are discussed and evaluated. Factors affecting the degree of resection and patient outcomes are presented. We emphasize our surgical techniques for resection of these tumors and we discuss the advantages of different approaches, depending on the relationship of the tumor to the optic nerves., Methods: Data for 50 patients with meningiomas involving the optic nerves who were surgically treated between 1991 and 2002 were reviewed, by using patient files, operative notes, and pre- and postoperative imaging and ophthalmological examination findings., Results: Thirty-one female patients and 19 male patients, with a mean age of 53 years, were treated. Thirty-one patients (62%) underwent complete tumor removal (Simpson Grade 1 or 2), and 19 patients underwent subtotal removal (Grade 4). Factors affecting the grade of resection were tumor size (P = 0.01), location (P = 0.007), and internal carotid artery encasement (P = 0.019). Patients who underwent Grade 1 or 2 resection exhibited a mean tumor size of 3.0 cm, and patients who underwent Grade 4 resection exhibited a mean tumor size of 4.1 cm. Only three patients had residual tumor on the optic nerve; all others had tumor in the cavernous sinus or at the orbital apex or exhibited vascular involvement. Visual outcomes were influenced predominantly by tumor size, preoperative visual function, and optic nerve encasement., Conclusion: Meningiomas that involve the optic nerves require special considerations and surgical techniques. Early decompression of the optic nerve within the bony canal allows identification and separation of the tumor from the nerve, permitting removal of the tumor from this area with minimal manipulation of the optic nerve.

Objective: We investigated the safety and efficacy of stereotactic radiotherapy as an alternative therapy to surgical resection for optic nerve sheath meningiomas (ONSMs)., Methods: Thirty patients and 33 optic nerves with ONSMs were treated with conventional fractionated stereotactic radiotherapy treatment (CF-SRT) between July 1996 and May 2001 with the use of a 6-MeV LINAC designed for and dedicated to radiosurgery. The LINAC technique involved daily CF-SRT involving a relocatable frame, an average of three isocenters, and high-radiation dose conformality established by noncoplanar arc beam shaping and differential beam weighting. The patients who were treated with CF-SRT were followed clinically with serial visual fields and radiographically with both magnetic resonance imaging and functional (111)In-octreotide single-photon emission computed tomography. The results of treatment were compared with a historical control group of ONSM patients who were either observed or treated surgically and then observed., Results: Our study population comprised 18 women and 12 men with a median age of 44 years (age range, 20-76 yr). The median isosurface radiation dose was 51 Gy (dose range, 50-54.0 Gy), and the median clinical follow-up time was 89 weeks (range, 9-284 wk). Of 22 optic nerves with vision before CF-SRT, 20 nerves (92%) demonstrated preserved vision, and 42% manifested improvement in visual acuity and/or visual field at follow-up. Comparison of our patients with a historical control group revealed preserved vision in only 16% of patients in a comparable period of observation, along with a 150% greater probability of visual improvement. Four patients (13%) had posttreatment morbidities, including visual loss (two patients), optic neuritis (one patient), and transient orbital pain (one patient). On magnetic resonance imaging studies, there was no evidence of tumor progression or recurrence in all patients, including tumor volume reductions noted in four patients. All six patients monitored with (111)In-octreotide scintigraphy demonstrated significant decreases in tumor activity after CF-SRT., Conclusion: To date, this article describes the largest reported series of ONSMs. Although longer follow-up is necessary, we think that CF-SRT represents a safe alternative to surgery and offers a higher likelihood of preserved or improved vision in patients with ONSM. Our analysis suggests that CF-SRT is also preferable to observation. Functional (111)In-octreotide single-photon emission computed tomographic scintigraphy provides a useful technique for the assessment of tumor control that complements serial posttreatment magnetic resonance imaging in patients with ONSMs.

Objective and Importance: Optic nerve choristoma is a rare lesion composed of adipose tissue and smooth muscle involving the optic nerve. Few cases have been reported., Clinical Presentation: A 20-year-old woman presented with a history of slowly progressive visual loss in the left eye. On T1-weighted magnetic resonance imaging studies, after frequency-selective fat saturation, an optic nerve mass was detected at the level of the optic canal with signal characteristics suggesting the diagnosis of optic nerve lipoma., Intervention: At left frontotemporal craniotomy, the intracranial optic nerve appeared thin and atrophic proximally and was covered by abundant adipose tissue distally. Because no cleavage plane could be identified between the fatty lesion and the optic nerve, which appeared splayed within the adipose tissue, the nerve was resected after an intraoperative biopsy. The presence of two heterotopic mesodermal elements, a rim of adipose tissue admixed with bundles of mature smooth muscle, extending into the nerve septa, warranted a diagnosis of optic nerve choristoma., Conclusion: Optic nerve choristoma is an uncommon optic nerve lesion. Even if imaging studies are highly suggestive of the diagnosis, pathological confirmation is required because of the high adipose tissue content in the majority of cases. The lesion, most likely malformative and nonneoplastic in nature, can be the cause of progressive visual loss.