A minimally invasive endoscope assisted retrosigmoid approach for removal of arachnoid cysts in the internal auditory canal: a step by step description / Abordagem retrosigmoide minimamente invasiva assistida por endoscopia para remoção de cistos aracnóides no conduto auditivo interno: descrição passo a passo

Abstract Introduction: Arachnoid cyst in the internal auditory canal is a quite rare pathology but due to its compressive action on the nerves in this district should be surgically removed. Several surgical techniques have been proposed but no surgeons have used the minimally assisted endoscope retrosigmoid approach for its removal. Objective: To investigate the feasibility of using a minimally invasive endoscope assisted retro-sigmoid approach for surgical removal of arachnoid cysts in the internal auditory canal. Methods: Minimally invasive endoscope assisted retrosigmoid approach allows to access to the internal auditory canal through a minimally invasive retrosigmoid approach that combines the use of a microscope and an endoscope. It is performed in six steps: soft tissue step, bone step, dura step, cerebellopontine angle step (performed using an endoscope and a microscope), microscope-endoscope assisted arachnoid cysts removal and closure. We tested minimally invasive endoscope assisted retrosigmoid approach for removal of arachnoid cysts in the internal auditory canal on two human cadaveric heads (specimens) of subjects affected from audio-vestibular disorders and with arachnoid cysts in the internal auditory canal confirmed by magnetic resonance imaging. Results: The mass was completely and successfully removed from the two specimens with no damage to the nerves and/or vessels in the surgical area. Conclusion: The results of our study are encouraging and support the feasibility of using minimally invasive endoscope assisted retrosigmoid approach for removal of arachnoid cysts in the internal auditory canal. While further clinical in-vivo studies are needed to confirm the accuracy and safety of using the minimally invasive endoscope assisted retrosigmoid approach for this specific surgery, our group has successfully used the minimally invasive endoscope assisted retrosigmoid approach in the treatment of microvascular compressive syndrome, schwannoma removal and vestibular nerve resection.

Resumo Introdução: O cisto aracnóide no conduto auditivo interno é uma doença bastante rara, mas, devido à sua ação compressiva sobre os nervos deste local, ele deve ser removido cirurgicamente. Várias técnicas cirúrgicas foram propostas, mas ninguém utilizou a abordagem retrosigmoide minimamente invasiva assistida por endoscopia para a sua remoção. Objetivo: Investigar a viabilidade do uso da abordagem retrosigmoide minimamente invasiva assistida por endoscopia para remoção cirúrgica de cistos aracnóides no conduto auditivo interno. Método: A abordagem retrosigmoide minimamente invasiva assistida por endoscopia permite o acesso ao conduto auditivo interno através de uma abordagem retrosigmóide minimamente invasiva que combina o uso de um microscópio e um endoscópio. É realizada em seis etapas: do tecido mole, óssea, dura-máter, do ângulo pontocerebelar (realizado com um endoscópio e um microscópio), remoção e fechamento assistidos por endoscópio-microscópico. Testamos a abordagem retrosigmoide minimamente invasiva assistida por endoscopia para remoção de cistos aracnóides no conduto auditivo interno em duas cabeças de cadáveres humanos (espécimes) de indivíduos afetados por distúrbios auditivos-vestibulares e com cistos aracnóides no conduto auditivo interno confirmado por imagem de ressonância magnética. Resultados: A lesão foi removida completamente e com sucesso nos dois espécimes sem dano aos nervos e/ou vasos na área cirúrgica. Conclusão: Os resultados do nosso estudo são encorajadores e apoiam a viabilidade do uso da abordagem retrosigmoide minimamente invasiva assistida por endoscopia para remoção de cistos aracnóides no conduto auditivo interno. Embora mais estudos clínicos in vivo sejam necessários para confirmar a precisão e a segurança do uso da abordagem retrosigmoide minimamente invasiva assistida por endoscopia para essa cirurgia específica, nosso grupo utilizou com sucesso a abordagem retrosigmoide minimamente invasiva assistida por endoscopia no tratamento da síndrome compressiva microvascular, remoção de schwannoma e ressecção do nervo vestibular.

Localización preoperatoria de la trepanación inicial en el abordaje retrosigmoideo. Revisión de literatura y aplicación quirúrgica / Preoperative location of the initial trepanation in the retrosigmoid approach. Literature review and surgical application

Objetivo: Evaluar una técnica eficaz y reproducible que permita determinar el sitio de la trepanación inicial en el abordaje retrosigmoideo. Materiales y métodos: Se empleó una muestra de 22 pacientes a fin de analizar la relación de la transición transverso ­ sigmoidea (TTS) con el asterion y la ranura digástrica. Todos los casos contaban con TC de cortes finos (1 mm de espesor). Se subdividieron los pacientes en dos grupos. Grupo 1: pacientes con patologías variables, sin alteraciones estructurales en la fosa posterior. Grupo 2: pacientes en los que se realizó un abordaje retrosigmoideo con planificación prequirúrgica del sitio de trepanación inicial. Discusión: Las referencias óseas (asterion y punto digástrico) pudieron identificarse en la totalidad de las TC 3D analizadas. Se analizaron las distancias empleando un sistema de coordenadas. La TTS se registró en el 78% de los casos anterior e inferior al asterion. En ningún caso se encontró la TTS superior al asterion, la ubicación en sentido inferior varió entre 0 mm y 25,5 mm (media 12,5 mm). En el plano anteroposterior, se registró una distancia entre -6,41 mm y 14,5 mm (media 4,09 mm), demostrando una gran variabilidad individual, comparable con lo descripto en la literatura. En el grupo 2, pudo predecirse de manera precisa la localización de la TTS, exponiendo la misma con la trepanación inicial. Conclusión: Se describe un método sencillo, eficaz, de libre acceso, que permite la ubicación del keyhole en el abordaje retrosigmoideo

Objective: To assess an effective and reproducible technique that allows determining the emplacement of the initial burr-hole in the retrosigmoid approach. Materials and methods: A sample of 22 patients was used to analyze the relation among the transverse - sigmoid transition (TTS), the asterion and the digastric groove. All cases had a thin-slice, 1-mm-thick Computed Tomography (CT). Patients were subdivided into two groups. Group 1: patients with variable pathologies, without structural modification of posterior fossa anatomy. Group 2: patients in which a retrosigmoid approach was performed with preoperative surgical planning of the initial burr-hole. Discussion: Bone references (asterion and digastric point) could be identified in the totality of the analyzed 3D CT. The distances were measured using a coordinate system. TTS was recorded in 78% of the cases inferior and anterior to the asterion. In no case the TTS was found superior to the asterion. It was 0 mm to 25.5 mm (mean 12.5 mm) inferior; and a distance between -6.41mm to 14.5mm (mean 4.09mm) in the anteroposterior plane was recorded, demonstrating a large individual variability. In group 2, the location of the TTS could be accurately predicted, exposing it with the initial burr-hole. Conclusion: A simple, effective and access free method is described, which allows the emplacement of the keyhole in the retrosigmoid approach

Reconstruction of anterior inferior cerebellar artery by occipital artery through extended retrosigmoid approach / 中华显微外科杂志

Objective To explore the feasibility of occipital artery(OA) to anterior inferior cerebellar artery (AICA) through the extended retrosigmoid approach,also perform a systemic microanatomical study of OA and AICA with the exposure of extended retrosigmoid approach,find the easy way to perform the procedure.Methods From September,2016 to January,2017,5 adult cadaveric heads injected with colored latex (total 10 sides) were performed the extended retrosigmoid approach,and measured the caliber of distal occipital artery (OA),the final length of the OA harvest,the reliable landmark of the OA harvest,and the distance from the flocculonodular segment of anterior inferior cerebellar artery (AICA) to the OA,the diameter of AICA flocculonodular segment branch.Whole procedure of OA to IACA bypass also be performed.Statistical analysis was performed.Results By the extended retrosigmoid approach,AICA flocculonodular segment could be easily exposure,the average diameter was 1.2 mm,the OA branch could be harvested in average was (72.3±3.3)mm in length from the occipital sulcus,and the average distance between occipital sulcus and AICA flocculonodular segment was (47.6±l.9)mm.The bypass procedure also could be performed through the proper corridor.Conclusion The Extended retrosigmoid approach is a safe and efficient way to perform the OA-AICA bypass procedure,and the procedure is easier to be performed than other surgical approaches.

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. .

Abordaje retrosigmoideo / Retrogigmoid approach

OBJETIVO: describir en forma detallada, paso a paso, la realización de un abordaje retrosigmoideo. DESCRIPCIÓN: posición: existen 3 posiciones descritas para la realización de este abordaje, semisentada, decubito dorsal y en banco de plaza. Incisión: se extiende desde la parte superior del pabellón auricular hasta 2 cm por debajo del vertice mastoideo, y 1 cm medial a la ranura digástrica. Disección de partes blandas: se realiza una disección subperiostica, teniendo especial cuidado con la vena hemisaria mastoidea (posible fuente de embolia aérea). Craniectomía: es necesario identificar previamente algunos puntos anatómicos de referencia para la ubicación de los senos transverso y sigmoides. En la etapa final de la remoción ósea, se procede al fresado de la porción más superior y lateral del abordaje, con la necesaria exposición de la porción inferior del seno transverso y de la porción medial del seno sigmoides. Apertura dural: se realiza una apertura en forma de letra "C" (lado izquierdo), o letra "C invertida" (lado derecho), con base medial, comenzando en la porción superior y medial de duramadre expuesta. Disección microquirúrgica: dependiendo de la ubicación de la patologia a abordar se debe realizar una retracción gentil del hemisferio cerebeloso hacia medial. En la mayoría de los casos es necesario abrir la cisterna cerebelobulbar, con el objeto de evacuar LCR. CONCLUSIÓN: el refinamiento alcanzado actualmente hace que el abordaje retrosigmoideo sea el más utilizado para el tratamiento de las múltiples patologías ubicadas en la región del ángulo pontocerebeloso. El acceso que proporciona esta vía a la mayoría de los nervios craneales que se encuentran en la fosa posterior, y a sus complejos neurovasculares correspondientes, lo convierte en un abordaje de obligatorio aprendizaje para todo neurocirujano

OBJECTIVE: the aim of this paper is to describe, step by step, the retrosigmoid approach to accessing the cerebellopontine angle (CPA). DESCRIPTION: patient position: three potential positions have been described for this approach: semi-sitting, dorsal decubitus and park bench. Incision: The incision extends from the top of the ear to 2 cm below the mastoid apex, and 1 cm medial to the digastric groove. Soft tissue dissection: A subperiosteal dissection is performed, taking special care to avoid the mastoid emissary vein. CRANIOTOMY: At the outset, it is necessary to identify certain anatomical landmarks to localize the transverse and sigmoid sinuses. Dural opening: The dural incision is made in the shape of the letter "C" on the left side or an inverted letter "C" on the right. Microsurgical dissection: Depending on the location of the pathology being treated, it may be necessary to perform gentle cerebellar retraction medially. CONCLUSIONS: the refinements now achieved with the retrosigmoid approach make it the most widely-used approach for the treatment of lesions located within the CPA. The access provided by this approach to the vast majority of the cranial nerves in the posterior fossa, as well as their neurovascular complexes, makes it a mandatory approach for all neurosurgeons to learn

Morphologic measurement of entry points and landmarks of retrosigmoid approach using volume rendering with thin-section computed tomography and its significance / 吉林大学学报(医学版)

Objective To research the jugular foramen,internal auditory pore (IAP)and the turning point between its components by imageological methods and to provide theoretical basis for retrosigmoid approach in the operation of acoustic neurinoma.Methods The skulls of 100 volunteers were scanned to get the final result with thin-section computed tomographic image. High-resolution spiral CT multiplane reformation was used to reform images that were parallel to the Frankfort horizontal plane to measure the distance between the turning point of retrosigmoid (A),the edge of jugular foramen(B)and the lower edge of the internal auditory canal(C)(denoted AC,AB,BC) and the shortest distance from the jugular foramen to AC.The angles between AC,AB and sagittal axis(α,β) were measured.Results The distance of AC was (44.94 ± 3.84)mm,the distance of AB was (43.68 ± 4.56)mm.The distance of BC was (6.15 ±2.04)mm,and the shortest distance between jugular foramen and AC was (5.21±0.23)mm.The angleαwas measured as (39.50±4.74)°,and the angleβwas measured as (46.35± 5.51)°.Conclusion The research measure the distance and angle between entry points and landmarks of retrosigmoid approach and the safe distance.

Three-dimensional individual digital anatomy for microsurgery of cerebellopontine angle region tumor / 中华显微外科杂志

Objective To summary the microsurgery clinical experience of 21 patients with cerebellopontine angle tumor by the help of three dimensional individual digital anatomy. And to evaluate the value of three dimensional individual anatomy in the treatment of tumors in cerebellopontine angle. Methods Between January 2011 and November 2011,21 patients with various cerebellopontine angle tumor,managed at the Third Affiliated Hospital of Sun Yat-Sen University, underwent CTA scan, and reconstruct the local anatomy by 3D view software. According to the individual anatomical model, the microsurgery program by restrosig moid approach was developed. Results All patients had reposition of the bone flap at original site after craniectomy during the same operative setting mentioned above with retrosigmoid approach. No complication was noted.Patients did not have any delayed postcraniectomy pain at operation site.Postoperative computed tomography of the skull showed good healing and shaping of the suboccipital bone at the surgical region. Conclusion With the help of three dimensional individual anatomy, the microsurgery of cerebellopontine angle tumor underwent less postoperative complications.This study provides a safe and effective individualized microsurgical methods by restrosig moid approach.

Retrosigmoid Approach in the Removal of Vestibular Schwannoma

BACKGROUND AND OBJECTIVES: The use of several approaches, involving different cerebellopontine angles, has enabled vestibular schwannoma removal to be tailored to each patient's pathology and physiological status. The retrosigmoid approach provides simple and direct access to cerebello-pontine angle lesions. SUBJECTS AND METHODS: We retrospectively assessed outcomes in 35 consecutive patients who underwent vestibular schwannoma removal via the retrosigmoid approach. RESULTS: Of the 35 patients, 12 were men and 23 women; their age was 52.5+/-10.4 years (range, 35-75 years). One tumor was small (3 cm). Symptoms included hearing disturbance (31 patients, 89%), tinnitus (14 patients, 40%), headache (12 patients, 34%), vertigo (11 patients, 31%), and facial palsy (9 patients, 25%). Postoperative complications included facial palsy, intracranial hemorrhage, dysphagia, and disseminated intravascular coagulopathy, with facial palsy remaining permanently. Four patients (11.4%) had tumor regrowth, at a mean of 36.3 months after primary surgery. The mean diameter of regrowing tumors was 20.5+/-4.4 mm (range 14.5-25.0 mm). CONCLUSIONS: The retrosigmoid approach for vestibular schwannoma removal was associated with higher rates of facial palsy and hearing loss. This approach, however, can minimize injury to the lower cranial nerve.

Retrosigmoid Approach in the Removal of Vestibular Schwannoma

BACKGROUND AND OBJECTIVES: The use of several approaches, involving different cerebellopontine angles, has enabled vestibular schwannoma removal to be tailored to each patient's pathology and physiological status. The retrosigmoid approach provides simple and direct access to cerebello-pontine angle lesions. SUBJECTS AND METHODS: We retrospectively assessed outcomes in 35 consecutive patients who underwent vestibular schwannoma removal via the retrosigmoid approach. RESULTS: Of the 35 patients, 12 were men and 23 women; their age was 52.5+/-10.4 years (range, 35-75 years). One tumor was small (3 cm). Symptoms included hearing disturbance (31 patients, 89%), tinnitus (14 patients, 40%), headache (12 patients, 34%), vertigo (11 patients, 31%), and facial palsy (9 patients, 25%). Postoperative complications included facial palsy, intracranial hemorrhage, dysphagia, and disseminated intravascular coagulopathy, with facial palsy remaining permanently. Four patients (11.4%) had tumor regrowth, at a mean of 36.3 months after primary surgery. The mean diameter of regrowing tumors was 20.5+/-4.4 mm (range 14.5-25.0 mm). CONCLUSIONS: The retrosigmoid approach for vestibular schwannoma removal was associated with higher rates of facial palsy and hearing loss. This approach, however, can minimize injury to the lower cranial nerve.

Schwannomas intracraneanos: nuestra experiencia (2000-2009) / Intracraneal schwannomas: our experience (2000-2009)

Objective. To present and evaluate the surgical results in the treatment of intracranial schwannomas. Method. We present 26 patients with intracranial schwannomas for a period of 10 years treated with surgery, analyze kind ofpresentation and postoperative results. Results. One of the cases corresponded to schwanoma of III pair, another case to schwanoma of the V pair, two other cases corresponded to schwanoma of the IX pair and twenty two cases corresponded to schwanomas of the VIII pair. Average age was 51,95 años (19-73). Total resection was made in 25 patients, partial resection was made in other. Facial nerve preservation was made in the remaining 22 patients. Preservation auditory nerve function was made in all the cases. We had 3 cases of cerebrospinal fluid leak.There were no mortal cases associated to the surgical procedure. Conclusion. The goal of treatment of intracranial schwanomas is total resection with anatomical and functional preservation of neurological structures around. This could be accomplished by retrosigmoid approach by experienced neurosurgeons.

Neuralgía del glosofaríngeo: presentación de dos casos / Glosspharyngeal neuralgia: report of two cases

Objective. To present 2 cases of glossopharyngeal neuralgia treated by microvascular decompression. Description. Case one. 37-year- old male suffering pain in the posterior region of the left half of the tongue for 3 years. The diagnosis was left glossopharyngeal neuralgia. We performed microvascular decompression with Teflon felt. The patient has improved however he is still under medication. Case two. 59-year-old female suffering pain in the posterior third of the left half of the tongue. The diagnosis was left glossopharyngeal neuralgia. We performed microvascular decompression with Teflon. Symptoms completely disappeared. Conclusion. Glossopharyngeal neuralgia is infrequent. It can be treated with microvascular decompression with good results.

A microscopic anatomy study of the retrosigmoid keyhole approach / 中国医师进修杂志

Objective To observe the microscopic anatomy structures of petroclival region via the retrosigmoid keyhole approach,then provide an anatomic basis for clinical application.Method Six adult cadaveric heads 6xed by 10% formaldehyde solution were used for simulating the retrosigmoid keyhole approach to observe major microscopic anatomy structures.Results By means of adjusting the microscope,structures such as the ipsilateral trigeminal nerves,cranial nerve,acoustic nerve,posterior nerves,anterior and lateral pons,lateral cerebellar hemisphere,anterior inferior cerebellar artery,vertebral artery,posterior inferior cerebellar artery were exposed via this keyhole approach.Conclusion This retrosigmoid keyhole approach is according with the minimally invasive principle,and represents a reasonable option for accessing the petroclival region.

Microanatomy and virtual anatomy of retrosigmoid approach / 解剖学报

Objective To explore the related structures of retrosigmoid approach by microanatomy and virtual anatomy and provide a reliable approach with more morphologic data. Methods Twenty sides of 10 adult cadaveric heads were dissected to simulate retrosigmoid approach under the microscope. The neurovascular structures of pontocerebellar trigone were observed, and the related structures were simultaneously measured based on the junction of superior petrosal sinus and sigmoid sinus and internal acoustic pore. The internal auditory canal was opened by drilling the margin of the internal auditory meatus and its structures were watched. With the help of Dexotroscope system, the data of five patients' CT and MRI were applied to reconstruct and anatomize the structure of retrosigmoid approach. Results It was found that the distance from the junction of superior petrosal sinus and sigmoid sinus to the trigeminal nerve was (38.50±2.64)mm, to the acoustic-facial bundle (27.80±2.25)mm, to the glossopharyngeal nerve (32.70±2.11)mm, to the hypoglossal nerve (44.30±2.05)mm, and the distance from internal acoustic pore to the trigeminal nerve was (5.68±1.55)mm, to the abducent nerve (13.80±1.81)mm, to the tentorium of cerebellum (5.00±0.66)mm, to the glossopharyngeal nerve (6.34±1.24)mm. The pontocerebellar trigone was divided into the anterior compartment, the middle compartment, the posterior compartment built on the acoustic-facial bundle and the glossopharyngeal nerve. Their structures were displayed after drilling the margin of the internal auditory meatus. Dexotroscope system clearly displayed asterion, the angle of transverse and sigmoid sinus, jugular foramen, internal acoustic pore, basilar artery and its branches, and theirs spatial relationship.Conclusion The three compartments of the pontocerebellar trigone are helpful to understand the feature of the neurovascular layer, the measurement is favorable to quantize the relation of the related structures and to judge the space of each compartment. Recognizing the anatomical marker of internal acoustic pore can support preservation of the inner structures. Virtual anatomy of Dexotroscope system can display local anatomical structure respectively. Both microanatomy and virtual anatomy have their advantages and disadvantages respectively and integration can be beneficial to understand neurovascular structures in the pontocerebellar trigone.

Long-term facial nerve clinical evaluation following vestibular schwannoma surgery / Avaliação clínica tardia do nervo facial no pós-operatório de schwannoma vestibular

BACKGROUND: Facial function is important in accompaniment of patients operated on vestibular schwannoma (VS). OBJETIVE: To evaluate long term facial nerve function in patients undergoing VS resection and to correlate tumor size and facial function in a long-term follow-up. METHOD: Transversal study of 20 patients with VS operated by the retrosigmoid approach. House-Brackmann Scale was used preoperatively, immediately after surgery and in a long-term follow-up. Student t test was applied for statistic analysis. RESULTS: In the immediate postoperative evaluation, 65 percent of patients presented FP of different grades. Improvement of facial nerve function (at least of one grade) occurred in 53 percent in the long-term follow-up. There was statistically significant difference in facial nerve outcome in long-term follow-up when tumor size was considered (p<0.05). Conclusion: The majority of patients had improvement of FP in a long-term follow-up and tumor size was detected to be a factor associated with the postoperative prognostic.

CONTEXTO: A função facial é importante para acompanhamento dos pacientes operados de schwannoma vestibular (SV). OBJETIVO: Avaliar o grau de paralisia facial (PF) em pacientes operados de SV, correlacionando tamanho do tumor com função facial na avaliação tardia. MÉTODO: Estudo transversal com análise seriada de 20 pacientes com SV operados pela via retrosigmóide-transmeatal. A Escala de House-Brackmann foi utilizada no pré-operatório, pós-operatório imediato e pós-operatório tardio. O teste t de Student foi aplicado para análise estatística. RESULTADOS: No pós-operatório imediato, 65 por cento dos pacientes apresentaram graus variados de PF, sendo que 53 por cento destes obtiveram melhora de pelo menos um grau de House-Brackmann na avaliação tardia. Houve diferença significativa no resultado da função facial no pós-operatório tardio quando o tamanho do tumor foi considerado (p<0.05).Conclusão: A maioria dos pacientes da amostra apresentou melhora da PF no pós-operatório tardio, sendo o tamanho do tumor um fator associado ao prognóstico.

Microsurgical resection of large acoustic neurinoma through suboccipital retrosigmoid approach / 中国微创外科杂志

Objective To evaluate the safety and efficacy of microsurgical resection of large acoustic neurinoma via the suboccipital retrosigmoid approach.Methods Forty-nine patients with large acoustic neurinoma(≥4 cm) underwent microsurgical resection through suboccipital retrosigmoid approach.The craniotomy was performed by way of an unilateral S-shaped suboccipital incision.With microsurgical techniques the outmost layer of the arachnoid membrane was preserved in order to avoid damaging to the surrounding vital structures.The tumor was resected intracapsularly from the superior pole and the internal auditory meatus was finally opened.The last pieces of tumor were removed by sharp dissection from the facial nerve bidirectionally,and were resected cautiously in a piecemeal fashion.Results Of the 49 patients,45 patients(92%) received a total resection of the tumors,and 4 patients(8%) subtotal resection.No patients died.The facial nerve was preserved anatomically in 42 patients(86%) and functionally in 36 patients(73%).The acoustic nerve was preserved anatomically in 7 patients(14%) and functionally in 3 patients(6%).One patient experienced a postoperative haematoma,and a re-operation was required.No recurrence was seen in 37 patients during a follow-up for 6 months ～ 5 years(mean,2.8 years).These patients had recovered for normal work and daily activities.Conclusions Microsurgical operation through suboccipital retrosigmoid approach is a favorable treatment for large acoustic neurinomas.The procedure can improve the rate of total resection,decrease the morbidity and mortality,and effectively protect the function of the acoustic and facial nerves.

Presigmoid Transpetrosal Approach for Recurrent Acoustic Neurinomas: Indications and Surgical Results

OBJECTIVE: In order to facilitate total removal with preservation of the facial nerve, the authors applied presigmoid(PS) approach in some patients with recurrent acoustic neurinoma(AN) patients who had undergone previous retrosigmoid(RS) approaches. The surgical outcomes of PS approach were retrospectively analyzed and compared to those of RS approaches and we suggest the indication of PS approach for recurrent AN. METHODS: From 1989 to 1999, twenty-one of 183 operated AN patients underwent re-operation due to regrowth of the residual tumors. Nine of the 21 recurrent tumors were removed by PS approach and 12 cases underwent RS approach. The surgical extent of removal and the facial nerve preservation rate were compared between the two different approaches. RESULTS: In PS approaches, the total removal was achieved in four patients(44%) and the facial nerve could be identified and preserved anatomically in all patients. Among 12 cases who underwent RS approaches, the rate of total removal was 44% and the facial nerve identified and preserved in only 5 cases (42%). The rate of facial nerve preservation was significantly different between two modes of approaches (p=0.0007). CONCLUSION: PS transpetrosal approach is recommended in recurrent AN patients who had underwent RS approach previously and already lost the hearing. Early identification of the facial nerve and easy removal of the tumors can be achieved using the PS approach.

The treatment of acoustic neuroma with microsurgery by retrosigmoid approach / 中华显微外科杂志

Objective To investigate the operative methods and clinical significance of the treatment for large acoustic ncuroma with microsurgery by retrosigmoid approach.Methods 15 cases of large acoustic neuroma treated with microsurgery by retrosigmoid approach were systematic analyzed,including the operative approach,microsurgical technique,disposal after operation,prevention and cure of complications.Results Tumors were totally removed in 12 cases and were subtotally removed in 3 cases.Facial nerve was kept ana- tomic intact in 13 cases(86.7%) and acoustic nerve was kept anatomic intact in 6 cases(40.0%).The short period complications happened in 3 cases and no patient died in this series.Conclusion Treatment for large acoustic neuroma with microsurgery by retrosigmoid approach is a safe method,which give small hurt brain tissue and benefit to increase the total removal rate and protect effectively the function of facial nerve and acoustic nerve.