Partial Labyrinth Removal Restricted to the Superior Semicircular Canal in Focal Combined Transpetrosal Approach: Description and Illustrative Cases.

BACKGROUND AND OBJECTIVES: The labyrinthine structures obstruct the surgical view of the deep petroclival region in the transpetrosal approach. Historically, labyrinthectomy and removal of all 3 semicircular canals, with resultant deafness, was used in patients with ipsilateral functional hearing deficits to improve access. The advent and systematization of superior and posterior semicircular canal removal (transcrusal approach) with good rates of hearing preservation has allowed a redefinition of the possibility of partial labyrinthectomy in patients without previous hearing deficits. The present manuscript is intended to describe a technical refinement of partial labyrinthectomy during focal combined petrosectomy, offering a customization of the approach through the selective removal of the superior semicircular canal for specific types of tumors. METHODS: The use of the technique is demonstrated through surgical drawings, pictures, and videos. The rationale to indicate this new approach is discussed based on clinical cases. RESULTS: Three illustrative clinical cases (petroclival meningiomas) are demonstrated. Functional hearing on the approach side has been preserved in all of them. CONCLUSION: The focal combined transpetrosal approach associated with the superior semicircular canal resection has been a promising surgical technique in the treatment of selected petroclival tumors. It has the potential to further decrease the risks of postoperative auditory and vestibular dysfunctions associated with labyrinthectomies.

Microsurgical Resection of Intracanalicular Vestibular Schwannoma via Retrosigmoid Approach: 3-Dimensional Operative Video.

Vestibular schwannomas are a multifaceted group of tumors that can present with different sizes and involvement of critical neurovascular structures.1-6 While operating on these tumors, a critical goal is postoperative preservation of facial nerve function and hearing. We present the case of a 66-year-old male with a history of severe left-sided tinnitus and progressive hearing loss (Video 1). Preoperative imaging depicted a lesion highly suggestive of an intracanalicular vestibular schwannoma. Due to worsening of symptoms and after thoughtful discussion with the patient, microsurgical resection was indicated under constant neurophysiologic monitoring. A retrosigmoid approach was employed, and the posterior wall of the internal auditory canal was opened, allowing exposure of tumor and its total resection. Postoperative imaging demonstrated complete tumor resection. The patient's symptoms improve, and there were no new neurologic deficits on follow-up. Anatomical images were a Courtesy of the Rhoton Collection, American Association of Neurological Surgeons (AANS)/Neurosurgical Research and Education Foundation (NREF).

Revisión sobre los conocimientos actuales de dehiscencia del canal semicircular posterior / Review of current knowledge of the dehiscence in the semicircular posterior canal

La dehiscencia del canal semicircular posterior es una patología rara y con baja incidencia, por ello hemos realizado una revisión de los conocimientos actuales de esta entidad. Se ha realizado una búsqueda bibliográfica desde 1998 hasta diciembre de 2016 de toda la literatura publicada sobre la misma en las bases de datos Allied and Complementary Medicine Database and the Embase, Health Management Information Consortium, Scopus, Consortium, Medline, PsycINFO y Scielo. Se han encontrado y revisado 53 trabajos relacionados con el tema. La dehiscencia del canal semicircular posterior presenta una prevalencia variable; 0,3%-4,5% en adultos y 1,2%-20% en niños. Su localización puede ser hacia el golfo de la yugular o fosa cerebral posterior. Los pacientes pueden ser asintomáticos o presentar clínica auditiva y/o vestibular. La tomografía computarizada y la prueba de potenciales vestibulares miogénicos evocados permiten establecer el diagnóstico de certeza. En el tratamiento quirúrgico la vía de abordaje de elección es la transmastoidea y las técnicas del cierre del canal son el "plugging" y el "resurfacing".

The posterior semicircular canal dehiscence is a rare pathology and it has a low incidence. We have realized a review about the current knowledge of this entity. We have performed a bibliographic research from 1998 to 2016 December about the literature published in this subject, in the data basis Allied and Complementary Medicine Database and the Embase, Health Management Information Consortium, Scopus, Consortium, Medline, PsycINFO y Scielo. I thas been found and reviewed 53 papers about the topic. The posterior semicircular canal dehiscence has a variable prevalence: 0,3%-4-5% in adults and 1,2%-20% in children. The location can be in the jugular bulb or in the posterior brain fossa. Some patients can be asymptomatic, whereas others can have auditory and/or vestibular signs and symptoms. Computed tomography and test of vestibular evoked myogenic potentials allow the diagnosis of certainty. In the surgical treatment the approach of choice is transmastoid and techniques to close the canal are plugging and resurfacing.

Surgical exposure of the internal auditory canal through the retrosigmoid approach with semicircular canals anatomical preservation.

OBJECTIVE: Evaluate the feasibility of an adequate exposure with anatomical preservation of labyrinth structures through retrosigmoid transmeatal approach (RSA) in surgeries for resection of acoustic neuromas/vestibular schwannomas (VS). METHOD: Thirty patients underwent surgical resection and were preoperatively evaluated with fine slice high definition CT scans and 3D-MRI volumetric reconstructions. Extension of internal auditory canal (IAC) opening during surgery was measured using 3 mm right-angle calibrated hook and neuronavigation parameters. Postoperatively, the extension of IAC opening and integrity of the labyrinth were confirmed through preoperatively images procedures. RESULTS: The preoperative length of IACs varied between 7.8 and 12.0 mm (mean 9.3 mm, SD 0.98, 95%CI 8.9 to 9.6, and median 9.0 mm). Postoperative images demonstrated adequate opening of the IAC and semicircular channels integrity. CONCLUSION: A complete drilling of the posterior wall of IAC through the RSA is feasible and allows direct visualization of the IAC-fundus without damaging the semicircular canals.

Surgical exposure of the internal auditory canal through the retrosigmoid approach with semicircular canals anatomical preservation / Avaliação da exposição do fundo do conduto auditivo interno através do acesso retrosigmóide-transmeatal

Objective Evaluate the feasibility of an adequate exposure with anatomical preservation of labyrinth structures through retrosigmoid transmeatal approach (RSA) in surgeries for resection of acoustic neuromas/vestibular schwannomas (VS). Method Thirty patients underwent surgical resection and were preoperatively evaluated with fine slice high definition CT scans and 3D-MRI volumetric reconstructions. Extension of internal auditory canal (IAC) opening during surgery was measured using 3 mm right-angle calibrated hook and neuronavigation parameters. Postoperatively, the extension of IAC opening and integrity of the labyrinth were confirmed through preoperatively images procedures. Results The preoperative length of IACs varied between 7.8 and 12.0 mm (mean 9.3 mm, SD 0.98, 95%CI 8.9 to 9.6, and median 9.0 mm). Postoperative images demonstrated adequate opening of the IAC and semicircular channels integrity. Conclusion A complete drilling of the posterior wall of IAC through the RSA is feasible and allows direct visualization of the IAC-fundus without damaging the semicircular canals. .

Objetivo Avaliar a possibilidade de exposição adequada preservando anatomia das estruturas labirínticas pelo acesso retrosigmóide-transmeatal (RSA) nas ressecções de schwannomas do vestibular (VS). Método Trinta pacientes foram submetidos à ressecção cirúrgica e avaliados no pré-operatório com tomografias de alta definição e reconstruções de ressonância magnética 3D. A extensão da abertura do conduto auditivo interno (CAI) foi medida e confirmada com parâmetros de neuronavegação. No pós-operatório, a extensão da abertura e a integridade do labirinto foram confirmadas por imagens de tomografia computadorizada. Resultados A extensão do CAI no pré-operatório apresentou variação de 7,8-12 mm (média 9,3 mm, DP 0,98, IC95% de 8,9-9,6 e mediana 9 mm). Imagens pós-operatórias demonstraram abertura adequada do IAC e integridade dos canais semicirculares. Conclusão A abertura completa da parede posterior do CAI pelo RSA é possível e permite a visualização direta do fundo do conduto sem prejudicar os canais semicirculares. .

Surgical anatomy of anterior and retrofacial approaches to sinus tympani.

OBJECTIVES: To define anatomic parameters indicating or limiting the use of anterior and retrofacial accesses to sinus tympani (ST). MATERIAL: Anatomic study (30 temporal bones). MAIN OUTCOME MEASURE: The profundity of the ST, the distance between the sigmoid sinus and facial nerve (SS-F), the distance from posterior semicircular canal to the facial nerve, and the capacity of adequate visualization of the ST. RESULTS: Sinus tympani depth was significantly smaller (

Tratamiento quirúrgico del vértigo: revisión bibliográfica / Surgical treatment of vertigo: a review

Se hace una revisión bibliográfica crítica de los procedimientos quirúrgicos usados para curar el síntoma vértigo, con objeto de aclarar sus indicaciones en función de resultados y de efectos nocivos. Las conclusiones a que se llegó fueron las siguientes: 1. En el vértigo producto de fístula perilinfática, se debe intervenir quirúrgicamente tan pronto sea diagnosticada y aún en casos de que solo exista una razonable sospecha. 2. En el vértigo postural paroxístico benigno incapacitante y resistente a tratamiento médico y rehabilitación física, se puede intervenir con obliteración del conducto semicircular posterior, informando al paciente, de preferencia por escrito, que existe riesgo, aunque poco probable, de que aparezca hipoacusia y acúfeno. 3. El vértigo ocasionado por la enfermedad de Meniére o por otros padecimientos, en caso de ser incapacitante y no susceptible a tratamiento médico, debe intervenirse siguiendo dos criterios: Cuando la audición ha disminuido hasta el punto de ya no ser útil, se puede emplear la gentamicina intratimpánica o la derivación del saco endolinfático; si estas fracasan, debe efectuarse laberintectomía. Cuando hay buena audición, o audición recuperable con auxiliar auditivo se puede hacer derivación del saco endolinfático; si ésta fracasa, neurectomía vestibular. 4. Hay razones para ser escéptico sobre la existencia y sobre la posibilidad diagnóstica del vértigo como producto de compresión vascular al tronco del nervio octavo, por lo que la descompresión microvascular del nervio debe considerarse como en fase experimental, y no efectuarse en ambiente clínico.