Hearing Function after CyberKnife for Vestibular Schwannoma: A Systematic Review.

Introduction CyberKnife (CK) radiosurgery is a treatment strategy for vestibular schwannoma (VS). Objectives To evaluate hearing preservation (HP) after CK for VS. Data Synthesis The study was conducted following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement, and it was registered at the International Prospective Register of Systematic Reviews (PROSPERO, under number CRD42021250300). The inclusion criteria were based on the population, intervention, comparison, outcome, timing and study design (PICOTS) strategy: population - patients with VS; intervention - CK; Comparison - none; Outcome - serviceable HP defined by Gardner and Robertson as grades I or II, or by the American Academy of Otolaryngology and Head and Neck Surgery as classes A or B; timing - mean follow-up longer than 1 year; and study design - retrospective or prospective studies. The exclusion criteria were: studies not published in English; studies published before January 2000 and after October 2021; and studies only including patients with neurofibromatosis type 2 or submitted to a previous treatment. The PubMed/MEDLINE, EMBASE, Web of Science, Cochrane Library, LILACS, and IBECS databases were used and last searched on October 27th, 2021. Statistical heterogeneity was assessed using I 2 statistics. The appraisal checklist was used to assess the risk of bias in the included studies. A total of 222 studies were analyzed, and 13 were included in the synthesis, which represents 493 participants with serviceable hearing before intervention. The mean HP rate after CK using a random effects model was of 68% (95% confidence interval [95%CI]: 59-76%) at a mean follow-up of 42.96 months. Conclusion The longer follow-up period was associated with a lower HP rate after CK radiosurgery for VS in the qualitative synthesis.

Combined open maxillectomy and endoscopic endonasal resection of a giant V2 trigeminal schwannoma.

BACKGROUND: Trigeminal schwannoma is a rare type of tumor that arises from the Schwann cells of the trigeminal nerve. METHOD: We present a case of a patient with a giant V2 trigeminal schwannoma with painful swelling in the left maxilla. A complete resection using a combined open maxillectomy and endoscopic endonasal approach was performed. CONCLUSION: This case highlights the importance of a multidisciplinary approach to perform a combined open and endoscopic approach for safe resection while preserving adequate speech and swallowing.

Neurofibroma Involving a Bifid Median Nerve in a Pediatric Patient: A Case Report.

Neurofibromas are benign peripheral nerve sheath tumors that typically develop within cutaneous nerve branches but can involve major nerves as well. They can be sporadic or associated with neurofibromatosis type 1. In this report, we describe the surgical treatment of a pediatric patient with neurofibromatosis type 1 presenting with a neurofibroma of a bifid median nerve. Involvement of the median nerve was not evident on preoperative examination or imaging, therefore altering the risk-benefit ratio of the procedure. After bifid nerve involvement was identified intraoperatively, the patient's parents were counseled on the risks and benefits of surgical excision before resuming the case. Ultimately, the neurofibroma was resected, and the patient experienced no neurological deficits after surgery.

Tumor maligno melanocítico de la vaina neural en mediastino posterior / Malignant melanotic nerve sheath tumor of the posterior mediastinum

Resumen El schwannoma melanótico (SM) es una variante rara e infrecuente caracterizada por el depósito citoplasmáti co de melanosomas (melanina). A diferencia de las otras variantes de schwannomas, tienen capacidad de malig nización. Por poseer características y comportamiento distintos al resto de los schwannomas, fue reclasificado como "tumor maligno melanocítico de la vaina neural" en la 5ta edición de la clasificación de los tumores del sis tema nervioso central de la Organización Mundial de la Salud en 2021. Presentamos dos casos de SM de ubicación mediastinal en los que se realizó una resección quirúrgi ca completa.

Abstract Melanotic schwannoma (MS) is a rare and infrequent subtype of schwannoma characterized by cytoplasmic deposits of melanosomes (melanin). Unlike the other schwannomas, it could have malignant transforma tion. Due to distinctive characteristics and atypical behavior from classic schwannomas subtypes, MS were renamed and reclassified as "melanocytic malignant neural sheath tumor" in the 5th ed. of the World Health Organization's classification of central nervous system tumors in 2021. We present two cases of MS that under went complete surgical resection.

The endoscopic transcanal approach to the internal auditory canal: an anatomic study.

PURPOSE: The internal auditory canal (IAC) plays a key role in lateral skull base surgery. Although several approaches to the IAC have been proposed, endoscope-assisted transcanal corridors to the IAC have rarely been studied. We sought to provide a step-by-step description of the transcanal transpromontorial approach to the IAC and analyze anatomic relationships that might enhance predictability and safety of this approach. METHODS: Ten cadaveric specimens were dissected and the extended transcanal transpromontorial approach to the IAC was established. Various morphometric measurements and anatomic landmarks were reviewed and analyzed. RESULTS: The proposed technique proved feasible and safe in all specimens. There was no inadvertent injury to the jugular bulb or internal carotid artery. The chorda tympani, a key landmark for the mastoid segment of the facial nerve, was identified in all dissections. The spherical recess of the vestibule and middle turn of cochlea are important landmarks for identification of the labyrinthine segment of the facial nerve. Identification of all boundaries of the working area is also essential for safe access. Among various morphometric measurements, the modiolus-IAC angle (≈ 150°) proved particularly consistent; given its ease of use and low variability, we believe it could serve as a landmark for identification and subsequent dissection of the IAC. CONCLUSIONS: The extended transcanal transpromontorial approach to the IAC is feasible and safe. Relying on anatomic landmarks to ensure preservation of the involved neurovascular structures is essential for a successful approach. The modiolus-IAC angle is a consistent, reproducible landmark for IAC identification and dissection.

[Malignant melanotic nerve sheath tumor of the posterior mediastinum]. / Tumor maligno melanocítico de la vaina neural en mediastino posterior.

Melanotic schwannoma (MS) is a rare and infrequent subtype of schwannoma characterized by cytoplasmic deposits of melanosomes (melanin). Unlike the other schwannomas, it could have malignant transformation. Due to distinctive characteristics and atypical behavior from classic schwannomas subtypes, MS were renamed and reclassified as "melanocytic malignant neural sheath tumor" in the 5th ed. of the World Health Organization's classification of central nervous system tumors in 2021. We present two cases of MS that underwent complete surgical resection.

El schwannoma melanótico (SM) es una variante rara e infrecuente caracterizada por el depósito citoplasmático de melanosomas (melanina). A diferencia de las otras variantes de schwannomas, tienen capacidad de malignización. Por poseer características y comportamiento distintos al resto de los schwannomas, fue reclasificado como "tumor maligno melanocítico de la vaina neural" en la 5ta edición de la clasificación de los tumores del sistema nervioso central de la Organización Mundial de la Salud en 2021. Presentamos dos casos de SM de ubicación mediastinal en los que se realizó una resección quirúrgica completa.

Retrosigmoid versus middle fossa approach for hearing and facial nerve preservation in vestibular schwannoma surgery: A systematic review and comparative meta-analysis.

BACKGROUND: Vestibular schwannomas (VS) are benign tumors arising from vestibular nerve's Schwann cells. Surgical resection via retrosigmoid (RS) or middle fossa (MF) is standard, but the optimal approach remains debated. This meta-analysis evaluated RS and MF approaches for VS management, emphasizing hearing preservation and Cranial nerve seven (CN VII) outcomes stratified by tumor size. METHODS: Systematic searches across PubMed, Cochrane, Web of Science, and Embase identified relevant studies. Hearing and CN VII outcomes were gauged using the American Academy of Otolaryngology-Head and Neck Surgery, Gardner Robertson, and House-Brackmann scores. RESULTS: Among 7228 patients, 56 % underwent RS and 44 % MF. For intracanalicular tumors, MF recorded 38 % hearing loss, compared to RS's 54 %. In small tumors (<1.5 cm), MF showed 41 % hearing loss, contrasting RS's lower 15 %. Medium-sized tumors (1.5 cm-2.9 cm) revealed 68 % hearing loss in MF and 55 % in RS. Large tumors (>3cm) were only reported in RS with a hearing loss rate of 62 %. CONCLUSION: Conclusively, while MF may be preferable for intracanalicular tumors, RS demonstrated superior hearing preservation for small to medium-sized tumors. This research underlines the significance of stratified outcomes by tumor size, guiding surgical decisions and enhancing patient outcomes.

A light in the darkness: sodium fluorescein-assisted peripheral nerve sheath tumors resection - a comprehensive systematic review and single-arm meta-analysis.

The treatment for peripheral nerve sheath tumors (PNSTs) is based on surgical excision and the primary goal is to improve symptoms whilst preserving neurological function. In order to improve this technique, surgeons may use sodium fluorescein (SF) to help visualize the neoplasm and, consequently, facilitate its removal. Aiming to assess the efficacy of this emerging surgical strategy, we conducted a systematic review and single-arm meta-analysis. We conducted a systematic search on the PubMed, Embase, and Web of Science databases, following the PRISMA guidelines. Studies without outcomes of interest, case series with less than four patients, letters, comments, technical notes, editorials, reviews, and basic research papers were excluded. The outcomes considered for this study were: the number of tumors that achieved total resection, subtotal resection, or near total resection, the approach/technique utilized by the surgeon, SF-related complications, and total complications. Five studies, with a total of 175 individuals, were included in our survey. Notably, 70% of the neoplasms presented by the patients were schwannomas. Considering extracranial lesions, we found a proportion of 96% (95% CI: 88 - 100%) in total resection, 0% (95% CI: 0-1%) in near total resection, and 4% (95% CI: 0-12%) in subtotal resection, all linked to an amount of 185 analyzed PNSTs. Furthermore, a proportion of 1% (95% CI: 0 - 2%) in SF-related complications was spotted among 183 patients. Finally, total complications analysis accounted for 11% (95% CI: 0 - 25%) among 183 individuals. We concluded that SF-assisted resection of PNSTs is a suitable and relatively safe technique, linked to minimum complications, of which the majority was not associated with the chemical compound itself. Future research is necessary to increase the number of patients available in the current literature and, therefore, enhance future analyses.

Schwannoma-like Breast Metastasis in the Meckel Cave: Case Report / Metástase de mama semelhante a um schwannoma no cavo de Meckel: Relato de caso

Tumors of the Meckel cave are very rare lesions, especially if they are malignant. We report the case of a patient who presented with a breast metastasis in the Meckel cave and a clinical presentation similar to that of a fifth nerve schwannoma.

Os tumores do cavo de Meckel são lesões muito raras, especialmente se forem malignos. Relatamos o caso de uma paciente que apresentou metástase mamária no cavo de Meckel e quadro clínico semelhante a schwannoma do quinto nervo.

Multiple Medullary Schwannoma Associated with Lumbar Disc Herniation and Cauda Equina Syndrome: Case Report / Schwannoma medular múltiplo associado a hérnia de disco lombar e síndrome da cauda equina: Relato de caso

Introduction Schwannoma is a Schwann cells neoplasm that can occur in various parts of the nervous system, including the medullar region of the cauda equina. Bone involvement is uncommon. Objective To report a multiple schwannoma case that was initially diagnosed as cauda equina syndrome. Clinical Case We report the case of a 44-year-old male who presented with pain irradiating to the lower limbs, urinary retention, and saddle paresthesia. Imaging exams revealed tumors in the cervical spine and in the T12/L1, L2/L3, and L3/L4 levels, the last three causing nervous compression. Histopathological analyses confirmed a Schwannoma pattern. Results The case was solved by surgical resection. Conclusion The case was solved and, in the end, the patient was stable and with improved pain and waits for a cervical surgery.

Introdução Schwannoma é uma neoplasia de células de Schwann que pode ocorrer em diversas partes do sistema nervoso, incluindo a região medular da cauda equina. O acometimento ósseo é incomum. Objetivo Relatar um caso de schwannoma múltiplo que foi diagnosticado inicialmente como síndrome da cauda equina. Relato de caso Relatamos o caso de um paciente masculino de 44 anos que apresentou quadro álgico com irradiação para os membros inferiores, retenção urinária e parestesia em cela. Exames de imagem revelaram tumores na cervical e em níveis de T12/L1, L2/L3 e L3/L4, com os três últimos causando compressão nervosa. A análise histopatológica comprovou padrão de schwannoma. Resultados A correção do quadro se deu através da ressecção cirúrgica. Conclusão O quadro foi resolvido com o paciente apresentando-se estável e com melhora do quadro álgico. O paciente aguarda cirurgia a nível cervical.

Endoscopic third ventriculostomy in hydrocephalus secondary to vestibular schwannomas / Tercer ventriculostomía endoscópica en la hidrocefalia secundaria a schwanomas vestibulares

Introduction: Treatment options for hydrocephalus related to posterior fossa tumors have been extensively studied in the pediatric population, but the value of endoscopic third ventriculostomy in hydrocephalus secondary to vestibular schwannoma in adults, is controversial. A systematic search of the medical literature was carried out in Pubmed/Medline and SciElo for the identification and inclusion of articles, in addition to the preprint servers bioRxiv and medRxiv. The following descriptors were used: hydrocephalus and vestibular schwannomas or acoustic neuromas or acoustic neurinomas and endoscopic third ventriculostomy. The initial search found 195 articles. After selection, 5 articles were chosen for the study. Objective: To specify the role of the endoscopic third ventriculostomy in hydrocephalus secondary to vestibular schwannomas. Development: The articles included a total of 82 patients, in which an improvement of the symptoms was achieved in 86.6 percent of the cases. The decrease in ventricular diameter was reported in 82.9 percent of the cases and was only found explicit in 3 articles. Although the failure criteria used were varied, 2 of them predominated: the persistence of progressive symptomatic hydrocephalus and/or the need for shunt placement. Endoscopic third ventriculostomy failure only represented 14.6 percent. Conclusions: Third ventriculostomy is an acceptable technique with relative success for the treatment of symptomatic obstructive hydrocephalus secondary to vestibular schwannomas(AU)

Introducción: Las opciones de tratamiento para la hidrocefalia relacionada con tumores de fosa posterior han sido ampliamente estudiadas en la población pediátrica, pero es controvertido el valor de la tercer ventriculostomía endoscópica, en la hidrocefalia secundaria a schwanoma vestibular en adultos, previo a la resección del tumor. Se realizó una búsqueda sistemática de la literatura médica en Pubmed/Medline y SciElo para la identificación e inclusión de artículos, además de los servidores de preprint bioRxiv y medRxiv. Se utilizaron los siguientes descriptores: hydrocephalus y vestibular schwannomas o acoustic neuromas o acoustic neurinomas y endoscopic third ventriculostomy. La búsqueda inicial encontró 195 artículos. Después de la selección, se eligieron 5 artículos para el estudio. Objetivo: Especificar el papel de la tercer ventriculostomía endoscópica en la hidrocefalia secundaria a schwanomas vestibulares. Desarrollo: Los artículos incluyeron un total de 82 pacientes, en los que se logró una mejoría de los síntomas en el 86,6 por ciento de los casos. La disminución del diámetro ventricular se reportó en el 82,9 por ciento de los casos y solo se encontró explícita en 3 artículos. Aunque los criterios de fracaso utilizados fueron variados, predominaron dos de ellos: la persistencia de hidrocefalia sintomática progresiva o la necesidad de colocación de derivación. La falla de la tercer ventriculostomía endoscópica solo representó el 14,6 por ciento. Conclusiones: La tercera ventriculostomía endoscópica es una técnica aceptable y con relativo éxito para el tratamiento de la hidrocefalia obstructiva sintomática secundaria a schwanomas vestibulares(AU)

Middle Ear Cholesteatoma and Vestibular Schwannoma Resection Followed by Cochlear Implant: Surgical Challenges and Audiological Outcomes.

(1) Background: The occurrence of vestibular schwannoma (VS) associated with cholesteatoma is rare. A hearing impairment is one of the most significant issues in such cases. Moreover, the presence of middle and inner ear pathologies combined may represent a surgical challenge. No studies have described a combined surgical approach for these coexisting conditions (VS and cholesteatoma), nor the hearing rehabilitation outcomes of using cochlear implants for these patients. (2) Case Report: This paper is on a female patient who underwent simultaneous surgical treatments for VS and middle ear cholesteatoma in the right ear followed by a cochlear implant, describing the technique and the audiological results. (3) Conclusions: The surgical approach was successful and enabled the resection of lesions with the auditory nerve and cochlea preservation. Cochlear implantation in the right ear showed positive postoperative results, with an improvement in the results with the CI in silent and noisy environments.

Intracanalicular vestibular schwannomas: facial and hearing outcomes according to the location of the tumor in relation to the nerves of the internal auditory canal.

OBJECTIVE: The objective was to evaluate whether the position of the nerves within the internal auditory canal (IAC) has any effect on preoperative and postoperative cochlear and facial nerve function in patients with intracanalicular vestibular schwannoma (VS) resected through the retrosigmoid transmeatal approach. METHODS: Forty-four patients with sporadic intracanalicular VS, from a series of 710 patients with VS who underwent operations from January 1993 to April 2022, were retrospectively reviewed. The pattern of displacement of the cranial nerves and tumor within the IAC was recorded. Tumors were divided into 2 types: type T1A lesions had only anteriorly displaced nerves, and type T1B had posteriorly displaced vestibular nerves and anteriorly displaced facial and cochlear nerves. Differences in surgical outcomes between groups in terms of facial nerve function and hearing preservation were evaluated. RESULTS: Thirty-five cases (79.5%) were T1A tumors and 9 were T1B (20.5%). Gross-total resection and anatomical preservation of the facial and cochlear nerves were achieved in all patients. Postoperatively, all patients with T1A VS maintained normal facial nerve function; however, among T1B VS patients, 6 (67%) retained House-Brackmann grade I, 2 worsened to grade II, and 1 worsened to grade III at 6 months (p = 0.006). The 27 T1A VS patients with serviceable hearing maintained this status, and an additional patient with nonserviceable hearing improved to serviceable hearing; among T1B VS patients, only 2 of the 5 patients with serviceable hearing remained as such, 2 evolved to nonserviceable hearing, and 1 lost hearing after surgery (p = 0.0022). T1B VS patients had a 24-fold risk of facial nerve deterioration (relative risk [RR] 25.2, 95% CI 1.42-448.57, p = 0.028) and a 32-fold risk of hearing deterioration (RR 32.7, 95% CI 1.93-553, p = 0.016) after surgery. CONCLUSIONS: In intracanalicular VS, postoperative cochlear and facial nerve function are directly related to the location of the tumor in relation to the nerves, with worse outcomes in cases where the tumor is located between the vestibular and facial-cochlear nerves.

Brazilian Society of Otology task force - Vestibular Schwannoma ‒ evaluation and treatment.

OBJECTIVE: To review the literature on the diagnosis and treatment of vestibular schwannoma. METHODS: Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on vestibular schwannoma were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions. RESULTS: The topics were divided into 2 parts: (1) Diagnosis - audiologic, electrophysiologic tests, and imaging; (2) Treatment - wait and scan protocols, surgery, radiosurgery/radiotherapy, and systemic therapy. CONCLUSIONS: Decision making in VS treatment has become more challenging. MRI can diagnose increasingly smaller tumors, which has disastrous consequences for the patients and their families. It is important to develop an individualized approach for each case, which highly depends on the experience of each surgical team.

Tratamiento multimodal en los schwanomas vestibulares grandes / Multimodal Treatment for Large Vestibular Schwannomas

Introducción: Los schwanomas vestibulares son lesiones clasificadas como grado I por la Organización Mundial de la Salud. Las opciones conductuales incluyen la observación, la radiocirugía o la resección microquirúrgica endoscópica. Objetivo: Describir el rol del tratamiento multimodal en los schwanomas vestibulares. Métodos: Se realizó una búsqueda sistemática de literatura médica para la identificación e inclusión de artículos en las siguientes bases de datos: PubMed/Medline, SciELO y Google Scholar, además de los servidores de preprints BioRvix y MedRvix. Se usaron los siguientes descriptores: vestibular schwanoma OR acoustic neuroma AND nerve centered approach OR combined approach AND partial resection OR subtotal resection OR near total resection. Se excluyeron editoriales, cartas al editor, libros, revisiones, metaanálisis y aquellos artículos con método deficiente de más de 20 años de publicación o sin mención al tema de interés. Fueron incluidos 16 artículos. Desarrollo: Los artículos incluyeron un total de 699 pacientes, de los cuales solo 228 (32,6 porciento) recibieron radioterapia en el período posoperatorio. El período de seguimiento promedió 49,6 meses. La preservación de la función facial se logró en el 88,3 porciento de los casos y el control tumoral en el 80,7 porciento. El estado de la preservación auditiva solo fue informado en el 50 porciento de los estudios. El uso de la radioterapia adyuvante mostró gran variabilidad. Conclusiones: El tratamiento multimodal para los schwanomas vestibulares grandes -compuesto por la resección subtotal, vaciamiento intratumoral, seguido de radiocirugía- se ha convertido en una opción plausible. Se necesita la publicación de mayor cantidad de reportes para ofrecer recomendaciones y estratificar la conducta(AU)

Introduction: Vestibular schwannomas are lesions classified as grade I by the World Health Organization. Behavioral options include observation, radiosurgery or endoscopic microsurgical resection. Objective: To describe the role of multimodal treatment for vestibular schwannomas. Methods: A systematic search of medical literature, for the identification and inclusion of articles, was carried out in the databases PubMed/Medline, SciELO and Google Scholar, as well as in the preprint servers BioRvix and MedRvix. The following descriptors were used: vestibular schwannoma OR acoustic neuroma AND nerve centered approach OR combined approach AND partial resection OR subtotal resection OR near total resection. Editorials, letters to the editor, books, reviews and metaanalyses were excluded, as well as articles with deficient method of more than 20 years of publication or not mentioning the topic of interest. Sixteen articles were included. Development: The articles included a total of 699 patients, of which only 228 (32.6 ) received radiotherapy in the postoperative period. The average follow-up period was 49.6 months. Preservation of facial function was achieved in 88.3 percent of cases; and tumor control, in 80.7 percent. Hearing preservation status was reported in only 50 percent of the studies. The usage of adjuvant radiotherapy showed great variability. Conclusions: Multimodal treatment for large vestibular schwannomas -composed of subtotal resection and intratumoral draining, followed by radiosurgery- has become a plausible option. The publication of a greater amount of reports is necessary to provide recommendations and stratify the behavior(AU)

Factores radiológicos predictores de grado de resección en pacientes con schwannomas vestibulares / Radiological factors that predict the degree of resection and functional preservation in patients with vestibular schwannomas

Introducción: Existen diversos factores predictores de grado de resección en la cirugía de los schwannomas vestibulares (SV). Nuestro equipo en Tucumán realizó un estudio sistemático perioperatorio con un protocolo específico de resonancia magnética (RM) en estos pacientes. El objetivo del presente estudio fue determinar la utilidad de la RM como predictor de grado de resección de los SV. Materiales y métodos: Se realizó un estudio de serie, de tipo correlacional, descriptivo y retrospectivo de pacientes operados de SV, por nuestro equipo en Tucumán, entre enero 2014 y diciembre 2020 (n:92). Se realizó correlación estadística, entre las características imagenológicas con el grado de resección. Resultados: Un tumor sólido aumenta 39,19 veces la probabilidad de tener una resección completa en comparación con un tumor quístico. Conclusión: La RM permite definir adecuadamente la consistencia tumoral; un tumor sólido se asocia a una mayor probabilidad de resección total(AU)

Background: There are various predictors of degree of resection surgery for vestibular schwannomas (SV). Our team in Tucumán carried out a systematic perioperative study with a specific magnetic resonance imaging (MRI) protocol in these patients. The objective of the present study was to determine the usefulness of MRI as a predictor of the degree of resection of VS. Methods: A serial, correlational, descriptive, and retrospective study of patients operated on for SV was carried out by our team in Tucumán, between January 2014 and December 2020 (n: 92). Statistical correlation was made between the imaging characteristics with the degree of resection. Results: A solid tumor increases 39.19 times the probability of having a complete resection compared to a cystic tumor. Conclusion: MRI allows to adequately define tumor consistency; a solid tumor is associated with a higher probability of total resection(AU)

Microsurgical Resection of a Giant Trochlear Nerve Schwannoma: 2-Dimensional Operative Video.

We present the case of a 17-year-old male, who complained of a 1-year onset of pulsatile headache, dysphagia, speech changes, and emotional lability. Neuroimaging revealed a large left-sided contrast-enhancing tumor located at the infratentorial space consistent with a large trochlear nerve schwannoma. The tumor was compressing the brainstem, obstructing the outflow of the third and lateral ventricles causing hydrocephalus, and disturbing the cortico-bulbar pathways bilaterally leading to the diagnosis of pseudobulbar palsy. After the patient consented the surgical procedure, he was operated through a subtemporal transtentorial approach placed in the lateral position. A lumbar drain was used for brain relaxation during the procedure and image guidance to define the limits of surgical exposure. A microsurgical technique was used, aiming to preserve the cranial nerves and the vascular structures running through the perimesencephalic cisterns. Gross total resection was achieved and clinical course remained uneventful aside from a transient third nerve palsy. Symptoms improved and the three-month follow-up revealed an almost complete function of the oculomotor nerve (Video 1). Trochlear nerve schwannomas are the rarest variety of the cranial nerve schwannomas. Depending on tumor size, clinical and neuroimaging signs of mass effect and brainstem compression, treatment can be observation, microsurgical resection through cranial base approaches or radiosurgery.1-5.

Schwanoma palatino en paciente pediátrico de 12 años: una rara presentación clínica / Palatine Schwannoma in a 12 year-old pediatric patient: a rare clinical presentation

El schwanoma es un tumor neural que se origina en las células de Schwann presentes en la vaina nerviosa cuya localización más frecuente a nivel oral es el dorso de lengua, siendo mucho más frecuente en adultos. En población pediátrica la presentación es muy rara siendo lengua su ubicación más frecuente, mientras que a nivel palatino solo se conocen 11 reportes en menores de 16 años. El objetivo de este reporte es presentar un caso clínico inusual de schwanoma palatino en un niño chileno de 12 años de edad, quien fue derivado con diagnóstico clínico presuntivo de carcinoma mucoepidermoide. El caso se complementó con radiografía panorámica, Conebeam, y luego biopsia incisional. Finalmente, se diagnosticó schwanoma palatino variedad sólida. Es importante considerar al schwanoma como diagnóstico diferencial en casos de tumores palatinos, en especial en casos pediátricos ya que se pueden presentar similares características clínicas a tumores de glándula salival.

The Schwannoma or neurilemmoma tumor originates from Schwann cells present in nerve sheaths. At oral level, its most frequent location is at the back of the tongue, being much more frequent in adults. In the pediatric population, this occurrence is rare and most frequently found in the tongue. At palatal level, only 11 reports are known in children under 16 years of age. The aim of this report is to present an unusual clinical case of palatal schwannoma in a 12-year-old Chilean boy, referred with a clinical diagnosis of mucoepidermoid carcinoma. The case was complemented with panoramic radiography and Cone beam, for its subsequent incisional biopsy. Finally, a solid palatal schwannoma was diagnosed. It is important to consider schwannoma as a differential diagnosis in cases of palatal tumors, especially in pediatric cases, since they can present similar clinical characteristics to salivary gland tumors.

Hybrid Neurofibroma/Schwannoma of the Oral Cavity: A Rare Case Report and Literature Review.

Hybrid peripheral nerve sheath tumors show combined features of more than one type of conventional benign peripheral nerve sheath tumors. There are few cases reported of hybrid peripheral nerve sheath tumors in the head and neck region. A 68-year-old female patient was referred for evaluation of an oral swelling lasting five years. Intraoral examination revealed a small mobile nodule located in the lower vestibule. The patient underwent excisional biopsy and microscopic evaluation showed typical features of neurofibroma enclosing areas with palisading nuclei compatible with Antoni A pattern, which are seen in schwannomas. These regions showed strong and diffuse immunoreactivity for S100 protein and moderate positivity in the neurofibroma area. CD34 was positive in the neurofibroma area and entrapped axons were positive for neurofilament. The final diagnosis was oral hybrid neurofibroma-schwannoma tumor. Hybrid peripheral nerve sheath tumors, although extremely rare, may arise within the oral cavity. To the best of our knowledge, this is the first neurofibroma-schwannoma tumor reported in the oral cavity. Recognizing hybrid peripheral nerve sheath tumors as a distinct clinicopathological entity is important because they may also be associated with syndromic disorders.

Sacral schwannoma: case report and review of the literature.

Schwannomas are tumors of the macroglia cells, most frequently localized to the brain, in the pontocerebellar angle. We present the case of a 53 year-old female patient who presented multiple times with diffuse abdominal pain and was initially diagnosed as having a complex right adnexal mass. Exploratory laparotomy found a retroperitoneal mass and later on, the presence of a sacral schwannoma was found, suspected initially on contrast magnetic resonance imaging of the abdomen and pelvis, and confirmed by means of lesional biopsy and histopathology. This is a rare and unusual presentation accounting for only 5% of this tumor location and poses a challenge for imaging diagnosis, directly impacting the approach to the patient and any future interventions. There are few reports in the literature about giant sacral schwannomas, but these tumors have been found to extend within the spinal space towards the vertebral space, even occupying part of the abdomen. Hence, the importance of recognizing the presence of this tumor as well as its imaging features.