Role of cervical vestibular evoked myogenic potentials (cVEMP) and auditory brainstem response (ABR) in the evaluation of vestibular schwannoma / Papel dos potenciais evocados miogênicos vestibulares cervicais (cVEMP) e potencial evocado auditivo de tronco encefálico (PEATE) na avaliação do schwannoma vestibular

Abstract Introduction: Cervical vestibular evoked myogenic potentials (cVEMP) can assess the integrity of the inferior vestibular nerve thereby promising to be a useful tool in the audiological test battery to diagnose vestibular schwannoma. Objective: To ascertain the utility of cVEMP in diagnosis of vestibular schwannoma in conjunction with the ABR and to evaluate whether the size of lesion has any effect on the cVEMP measures. Methods: Case-files of 15 known cases of vestibular schwannoma whose pure tone audiometry, auditory brainstem response (ABR), cVEMP and radiological investigation findings were available, were included in the study. Patients were categorised as large or small tumours based on the size. The absolute and inter-peak latencies of ABR, amplitudes of waves V and I, and inter-aural latency difference of wave V of ABR; and latency of P1 and N1 of cVEMP and amplitude of P1-N1 complex were considered in the study. Results: There were eight large and nine small tumours. All the patients with large tumours showed significant severity of hearing loss whereas only three out of nine patients with small tumours showed severe to profound deafness in the affected ear. The rest showed hearing status ranging from normal hearing sensitivity to moderate hearing loss. Most of the patients with large tumours showed complete absence of ABR in the affected ears with no identifiable wave-peaks. ABR in small tumours exhibited delayed III-I and delayed V-I interpeak latency interval (IPL). Four out of five patients with large unilateral tumours revealed contralateral effects of reduced amplitude or absence of cVEMP. On the contrary, six out of eight unilateral small tumours showed a normal cVEMP response in the contralateral ear. Both the patients with NF2 in the present study demonstrated cVEMP abnormalities. Conclusion: ABR and cVEMP, when used in combination, can be of immense use in identification of neuro-otologic conditions such as vestibular schwannoma and bilateral tumours in NF2. In the evaluation of unilateral vestibular schwannoma, abnormal contralateral findings of cVEMP and ABR are strongly indicative of the tumour size >2.5 cm. In unilateral severe to profound loss wherein ABR in poorer ear cannot give information of site-of-lesion, cVEMP can help in the differentiation.

Resumo Introdução: Os potenciais evocados miogênicos vestibulares cervicais (cVEMP) podem avaliar a integridade do nervo vestibular inferior, prometem assim ser uma ferramenta útil na bateria de testes audiológicos para o diagnóstico de schwannoma vestibular. Objetivo: Determinar a utilidade de cVEMP no diagnóstico de schwannoma vestibular em conjunto com PEATE e avaliar se o tamanho da lesão tem qualquer efeito sobre as medidas do cVEMP. Método: Quinze casos diagnosticados com schwannoma vestibular cujos exames de audiometria tonal pura, potencial evocado auditivo de tronco encefálico (PEATE), cVEMP e investigação radiológica estavam disponíveis foram incluídos no estudo. Os pacientes foram classificados como portadores de tumores grandes ou pequenos. As latências absolutas e interpico de PEATE as amplitudes das ondas V e I e a diferença de latência interaural da onda V da PEATE e a latência de P1 e N1 de cVEMP e amplitude do complexo P1-N1 foram consideradas no estudo. Resultados: Havia oito tumores grandes e nove pequenos. Todos os pacientes com tumores grandes apresentavam perda auditiva grave enquanto apenas três dos nove pacientes com pequenos tumores apresentaram surdez grave a profunda na orelha acometida. O restante apresentou audição que variou de normal a perda auditiva moderada. A maioria dos pacientes com tumores grandes demonstrou ausência completa de PEATE nas orelhas acometidas sem picos de onda identificáveis. O PEATE em tumores pequenos apresentou intervalo de latência interpico (ILI) tardia III-I e tardia V-I. Quatro em cada cinco pacientes com tumores grandes unilaterais revelaram efeitos contralaterais de amplitude reduzida ou ausência de cVEMP. Ao contrário, seis dos oito tumores pequenos unilaterais apresentaram resposta de cVEMP normal na orelha contralateral. Ambos os pacientes com NF2 no presente estudo demonstraram anormalidades na cVEMP. Conclusão: PEATE e cVEMP, quando usadas em combinação, podem ser úteis na identificação de condições neuro-otológicas como schwannoma vestibular e tumores bilaterais em NF2. Na avaliação de schwannoma vestibular unilateral, achados contralaterais anormais de cVEMP e PEATE são fortemente indicativos de tumor >2,5 cm. Na perda unilateral grave a profunda, na qual o PEATE na orelha mais prejudicada não fornece informações do local da lesão, cVEMP pode ajudar na diferenciação.

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. .

The extracisternal approach in vestibular schwannoma surgery and facial nerve preservation / A abordagem extracisternal na cirurgia de schwannoma vestibular e preservação do nervo facial

The classical surgical technique for the resection of vestibular schwannomas (VS) has emphasized the microsurgical anatomy of cranial nerves. We believe that the focus on preservation of the arachnoid membrane may serve as a safe guide for tumor removal. Method The extracisternal approach is described in detail. We reviewed charts from 120 patients treated with this technique between 2006 and 2012. Surgical results were evaluated based on the extension of resection, tumor relapse, and facial nerve function. Results Overall gross total resection was achieved in 81% of the patients. The overall postoperative facial nerve function House-Brackmann grades I-II at one year was 93%. There was no recurrence in 4.2 years mean follow up. Conclusion The extracisternal technique differs from other surgical descriptions on the treatment of VS by not requiring the identification of the facial nerve, as long as we preserve the arachnoid envelope in the total circumference of the tumor. .

A técnica cirúrgica clássica para ressecção de schwannomas vestibulares enfatiza a anatomia microcirúrgica dos nervos cranianos. Acreditamos que o foco na preservação da membrana aracnóide pode servir como parâmetro seguro para a remoção do tumor. Método A abordagem extracisternal é descrita em detalhe. Analisamos o prontuário de 120 pacientes tratados com esta técnica entre 2006 e 2012. Os resultados cirúrgicos foram baseados em extensão de ressecção, recorrência tumoral e função do nervo facial. Resultados Ressecção total foi obtida em 81% dos pacientes. O resultado global da função do nervo facial (House-Brackmann graus I-II) após um ano da cirurgia foi de 93%. Não houve recidiva em um seguimento médio de 4,2 anos. Conclusão A técnica extracisternal difere de outras descrições cirúrgicas no tratamento de schwannoma vestibular pois não requer a identificação do nervo facial, contanto que o plano de aracnóide seja preservado em toda circunferência do tumor. .

Role of magnetic resonance imaging in evaluation of cerebellopontine angle tumors

Objective: to determine the role of MRI in evaluation of different Cerebellopontine angle tumors, and differentiation between them

Materials and Method: This study was conducted in the period between January 2009 and December 2012. Fifty four patients with CPA masses were selected on bases of neurotological complains that related to CPA

Results: Cerebellopontine angle masses in this study were classified into two groups: acoustic neuromas and non acoustic neuromas CPA masses. Twenty eight of cases [51.8%] were acoustic neuromas in which 26 cases were unilateral acoustic neuromas and 2 cases with bilateral neuromas, the remaining 26 cases [48.2%] were other non acoustic CPA masses. These included, one trigeminal neuroma [1.9%], 6 [11.1%] cases were CPA meningiomas, 6 [11.1] cases were epidermoid, 3 [5.6%] cases were arachnoid cyst, 2 [3.7%] cases were glomus jugulare tumors, 3 [5.6%] cases metastatic tumors and 5 [9.2%] cases were intraaxial and intraventricular tumors extending to the CPA, this included 2 cases cerebellar hemangioblastoma, 1 case pontine glioma and 2 cases were fourth ventricular ependymoma

Conclusion: MR imaging is considered the imaging method of choice to assess CPA tumors and to distinguish between them

Vestibular schwannoma: 825 cases from a 25-year experience

Introduction: Acoustic nerve tumors have been recognized as a clinico-pathologic entity for at least 200 years, and they represent 90% of cerebellopontine angle diseases. Histologically, the tumors are derived from Schwann cells of the myelin sheath, with smaller tumors consisting of elongated palisade cells, while in large tumors, cystic degeneration can be found in the central areas, possibly due to deficient vascularization. We retrospectively reviewed 825 cases of vestibular schwannomas, reported between January 1984 and August 2006, in which the patients underwent surgery to remove the tumor. Objective: To evaluate signs, symptoms, aspects of clinical diagnosis, including the results of audiological and imaging studies, and surgical techniques and complications. Methods: A retrospective chart review. The medical records of all patients undergoing surgical treatment for schwannoma during the period indicated were reviewed. Results and Conclusion: Hearing loss was the first symptom reported in almost all cases, and tumor size was not proportional to the impairment of the auditory threshold. The surgical techniques allowed safe preservation of facial function. In particular, the retrolabyrinthine route proved useful in small tumors, with 50% preservation of hearing...

[Magnetic resonance imaging findings in sudden sensorineural hearing loss]

Sudden deafness [SD] is one of the major complaints of patients who referred to otolaryngology or neurology clinics. Most of the cases have idiopathic etiology; but some of them have other causes that must be diagnosed by appropriate diagnostic modalities such as Magnetic Resonance Imaging [MRI]. In this study, we showed the findings of MR Imaging in 32 patients with SD. Determination of MRI findings in sudden sensorineural hearing loss. We had performed gadolinium enhanced brain MRI, along Brainstem Auditory Evoked Potentials [BAEP] before treatment in 32 patients with SD referring to ENT Clinics of Kashani hospital in Isfahan and Amiralmomenin hospital in Rasht from August 2005 to September 2008 and were analyzed their results. Abnormal findings in MRI were reported in 6 cases [19.35%]. In 3 cases [2 females, 1 male] were found cerebello-pontine angle tumors in the same side of suggesting 8th cranial nerve schwannoma [acoustic neurinoma]. In one 45 years old male were found multiple hyperintense lesions in T2 and FLAIR that were hypo to isosignal in T1 and PD in pons, left cerebellar hemisphere and middle cerebellar peduncle that were more compatible with infectious, carcinomatous or lymphomatous processes and in 2 other cases, inflammatory process in mastoid regions, like mastoiditis were seen. Subcortical and periventricular lesions were found in one patient, compatible with migrainous changes and without any relating to SD. In one case MRI was normal but were found abnormal BAEP findings which indicatived an auditory neuropathy. In the investigation of the etiology of SD in patients, MRI is an invaluable instrument and can identify and clear up structural causes of sudden deafness

Mixed vestibular schwannoma and meningioma without neurofibromatosis

The co-existence of meningioma and schwannoma as 2 distinct histologic components within the same tumor has been described in neurofibromatosis 2 [NF2], but the co-existence of both tumors without evidence of NF2 is much rarer. Here, we are reporting a case of mixed schwannoma with meningioma without clinical evidence of NF2. In an adult Saudi lady with progressive left-sided hearing loss, left cerebellopontine tumor was diagnosed by MRI, and the histopathological diagnosis revealed that this tumor was composed of vestibular schwannoma and meningioma. This case is discussed with literature review

Neurinoma del acústico (schwanoma vestibular): revisión y actualización de la literatura: [revisión] / Acoustic neuroma (vestibular schwannoma): a literature review: [revision]

El neurinoma del acústico corresponde al tumor más frecuente del ángulo pontocerebeloso. En su etiopatogenia se involucran factores genéticos que permiten su aparición, estando en algunos casos ligados a enfermedades como la neurofibromatosis tipo 2 expresándose de manera bilateral. Clínicamente se divide en 4 estadios que desencadenan una diversa gama sintomatológica de acuerdo al grado de compresión y ocupación del conducto auditivo interno y tronco encefálico, sin embargo la hipoacusia sigue siendo el síntoma más importante en su presentación. Estos son el estadio intracanalicular, cisternal, de compresión de tronco encefálico e hidrocefálico. Habitualmente alcanzan un tamaño que fluctúa entre los pocos milímetros hasta más de 3 centímetros de diámetro dividiéndose en pequeños, medianos y grandes. Asimismo se ha dicho que poseen un lento crecimiento e historia natural incierta mostrando la mayoría de los estudios cifras de crecimiento entre los 1-3 mm/año. Para la orientación diagnóstica la audiometría de tonos puros sigue siendo el examen más orientador en una primera etapa, sin embargo el estudio imagenológico con resonancia magnética contrastada con gadolinio resulta fundamental para la confirmación en la actualidad. En lo que al manejo respecta existen 3 alternativas razonables dependiendo del caso en particular como son la conducta expectante, la microcirugía y la radioterapia estereotáxica o Gamma Knife. Cada una de ellas posee factores a favor como en contra, por lo que la decisión terapéutica final se tomará considerando la velocidad de crecimiento, el tamaño tumoraly sintomatología siendo fundamental las prioridades del paciente.

Acoustic neuroma is the most frequent ponto cerebellar angle tumor. Genetic factors are involved in its etiology and in occasions its origins can be linked to diseases such as bilaterally expressing type 2-neurofibromatosis. Clinically acoustic neuromas can be classified in 4 stages, which result in diverse symptoms, according to the degree of brain stem and internal auditory canal compression or obstruction; however, hearing loss remains as the most important presenting symptom. The four stages are: intracanalicular, cisternal, brain stem compressive and hydrocephalic. Frequently they reach between few millimeters to more than 3 centimeters in diameter, and are accordingly ranked as small, medium-sized, and large. They have been reponed as having slow growth and uncertain natural history; in most studies growth rafes fluctuate between 1-3 mm/year Pure tone audiometry is the procedure of chote for diagnosis orientation in the first place, however, gadolinium-contrasted magnetic resonance imaging is currently pivotal for diagnosis confirmation. As for management, there are three reasonable alternatives, depending on a given case particularity. These are monitoring, microsurgery and stereotactic radiotherapy or gamma knife. Each one of them has its pros and cons, and thus the final therapy decisión will depend on the symptoms and tumor growth rate andsize, príorizlng thepatient well-being.

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.

Schwannoma vestibular: involução tumoral espontânea / Vestibular Schwannoma: spontaneous tumor involution

A história natural dos schwannomas vestibulares ainda não está totalmente elucidada, mas sua maioria tende a apresentar crescimento lento, muitos permanecendo sem sintomas durante toda a vida do paciente. Cerca de 69 por cento deste tipo de tumor diagnosticados não apresentam crescimento e, destes, 16 por cento chegam a apresentar regressão tumoral. Considerando os tumores que apresentam crescimento, cerca de 70 por cento crescem menos de 2 mm ao ano. O avanço nos métodos de diagnóstico por imagem, particularmente à ressonância magnética com contraste de gadolínio, permite o diagnóstico cada vez mais de lesões com sintomas mínimos e tamanhos menores. O tratamento de escolha para estes tumores ainda é a ressecção completa do tumor. As técnicas cirúrgicas apresentaram grande avanço nas últimas décadas, o que possibilitou diminuição da mortalidade. Assim, a cirurgia, que antes tinha como objetivo apenas a ressecção completa do tumor, agora visa também à preservação da audição e da função do nervo facial. Considerações finais: Considerando-se sua história natural, abre-se a possibilidade de uma conduta conservadora já que o ritmo de crescimento no primeiro ano após o diagnóstico prediz o comportamento do tumor nos próximos anos. A conduta conservadora não implica em repúdio à cirurgia, devendo ser utilizada em casos de aumento tumoral, piora dos sintomas ou desejo do paciente. Além disso, em relatos de literatura não há diferença estatisticamente significante entre os pacientes submetidos à cirurgia logo após o diagnóstico ou após conduta conservadora inicial, no que diz respeito às seqüelas pós-operatórias.

The natural history of Vestibular Schwannomas (VS) is yet not totally known, but most of them have the tendency to slow growth, sometimes without any kind of symptoms during the individual’s entire time. About 69 percent of diagnosed VS do not grow at all and 16 percent of these can even regress. Considering tumors that grow, about 70 percent have grown less than 2mm an year. Advanced radiological diagnosis, especially magnetic resonance imaging with gadolinium helps us diagnose small and less symptomatic tumors. Treatment of choice still is complete tumor resection. Surgical approaches have improved considerably and have helped preserve facial nerve function and hearing. Considering VS’s natural history, there is a possibility for conservative treatment for these tumors, because their growth in the first year after diagnosis predicts tumor growth behavior in the next years. Surgery should be done in cases of tumor growth, patient’s desire or symptoms worsening. Moreover, in terms of postoperative sequelae, there is no difference between patients who underwent surgery immediately after diagnosis and those who underwent initial conservative treatment for these tumors.

Acoustic neuroma (vestibular schwannoma): surgical results on 240 patients operated on dorsal decubitus position

OBJECTIVE: To evaluate the result of the surgical treatment of vestibular schwannoma (VS) operated in dorsal decubitus (mastoid position). METHOD: 240 patients with a VS underwent a retrosigmoid craniotomy for tumor resection in dorsal decubitus (mastoid position). The function of 7th and 8th cranial nerves was monitored during surgery and the opened internal auditory canal (IAC) was reconstructed using a vascularized dura flap, muscle and fibrin glue. RESULTS: Complete tumor removal was achieved in 99 percent of the cases, with a mortality of 1.6 percent. The facial nerve function was preserved in 85 percent of cases and hearing in 40 percent of the patients (with preoperative hearing) with tumors of up 1.5 cm in diameter. The incidence of cerebrospinal fluid leak was 5.8 percent and meningitis 2.9 percent. Venous air embolism was registered in 3 percent of cases; it was not associated to mortality. CONCLUSION: Surgical removal of VS in dorsal position has several advantages; the morbidity and mortality are very low.

OBJETIVO: Avaliar o resultado do tratamento cirúrgico de pacientes portadores de schwannoma do vestibular (SV) operados em decúbito dorsal (posição de mastóide). MÉTODO: 240 pacientes foram submetidos a craniotomia retrosigmóide na posição de mastóide. A função do VII e VIII nervos cranianos foi monitorizada durante a cirurgia e a reconstrução da abertura do conduto auditivo interno foi realizada com retalho vascularizado de dura-mater, músculo e cola de fibrina. RESULTADOS: A exérese foi completa em 99 por cento dos casos, com mortalidade de 1,6 por cento. Houve preservação da função do nervo facial em 85 por cento dos casos e da audição em 40 por cento dos pacientes com audição prévia e tumores menores de 1,5 cm. A incidência de fístula liquórica foi 5,8 por cento e meningite 2,9 por cento. Embolia gasosa foi registrada em 3 por cento dos casos, não associada à mortalidade. CONCLUSÃO: O tratamento cirúrgico dos SV utilizando-se a posição de mastóide tem várias vantagens, com baixa morbidade e mortalidade.

Associação entre tamanho e potencial proliferativo em neurinomas do acústico / Size and proliferative index correlation in acoustic neuromas

Schwanomas do acústico são os tumores mais freqüentes localizados no ângulo pontocerebelar. Os mecanismos moleculares que levam a sua geração e crescimento ainda não são bem conhecidos. Várias características clínicas, radiológicas e imuno-histoquímicas já foram estudadas e correlacionadas ao crescimento tumoral. Estudamos e correlacionamos aspectos clínicos e imuno-histoquímicos (MIB-1) de 11 schwanomas do acústico operados no Hospital São Paulo/UNIFESP. O tamanho dos tumores correlacionou-se com o índice proliferativo (Ki-67), não havendo correlação com significância estatística entre a idade dos pacientes, duração dos sintomas e índice proliferativo.

A Case of Medullomyoblastoma of Cerebellopontine Angle Mimicking Acoustic Neuroma

Medulloblastoma is a common malignant central nervous system neoplasm found mainly in children. One the contrary, medulloblastoma of the cerebellopontine angle, the location of the tumor is very unusual. This is the the first case of the medullomyoblastoma, a rare form of medulloblastoma, occurring in the cerebellopontine angle. A 15-year-old boy experienced a sudden hearing loss in the left ear. Conservative medical treatment failed, and temporal MR imaging revealed a heterogeneously enhancing mass at the left cerebellopontine angle cistern and in the internal auditory canal; therefore, the lesion was regarded as a typical acoustic neuroma. Few days before surgery, an ipsilateral facial palsy developed, and a follow-up MR imaging showed a rapid growth of the previous lesion. The extended translabyrinthine approach permitted surgical removal. And under pathological diagnosis of malignancy, radiation therapy and series of chemotherapy was performed.

A hypothesis of epiarachnoidal growth of vestibular schwannoma at the cerebello-pontine angle: surgical importance.

AIMS: The purpose of this study is to clarify the rearrangement of the arachnoid membrane on the vestibular schwannoma during its growth in relation to adjacent neurovascular structures for a better understanding of dissecting plane of arachnoid during surgery. METHODS: Arachnoid membrane over the tumour was investigated during surgery with suboccipital transmeatal approach in twenty-six tumours. All microsurgical procedures were recorded with a video and reviewed. The tumour growth was classified into five stages depending upon the tumour diameter in the cerebello-pontine (CP) angle: Stage 1; purely intracanalicular (2 cases), Stage 2; less than 5 mm (2 cases), Stage 3; > or = 5 and <15 mm (8 cases), Stage 4; > or = 15 and <25 mm (9 cases) and Stage 5; > or = 25 mm (5 cases). Rearrangement of the arachnoid on the tumour was conceptualised throughout all stages. RESULTS: All tumours of Stage 1 and 2 were entirely located in the subarachnoid space of the cerebello-pontine cistern without arachnoidal rearrangement, while all tumours of Stages 3 to 5 were enveloped, in the CP angle, with invaginated arachnoid membrane consisting of cerebello-pontine cistern except two surfaces; the medial pole and the tumour surface under the facial and cochlear nerves near the porus. CONCLUSION: The tumour originates subarachnoidally within the internal auditory meatus (IAM) and grows epiarachnoidally in the CP angle. Rearrangement of the arachnoid begins with its adhesion on the medial pole of the tumour along the porus, resulting in the arachnoidal invagination into the cerebello-pontine cistern with further growing of the tumour.

Vestibular Schwannoma with Malignant Transformation: A Case Report

We describe a rare case of malignant transformation in a vestibular schwannoma in a 33-yr-old woman. She presented herself with headache, tinnitus, and hearing loss and underwent posterior fossa explorations three times during the short period of 3 months. The clinicopathological features of the original tumor were typical of benign vestibular schwannoma. Despite a comlpete microsurgical excision, two months later, the tumor recurred locally with a rapid increase in size causing a progressive worsening of neurological symptoms. A diagnosis of malignant schwannoma was made for the recurrent tumor on the basis of the microscopic findings of high cellularity, moderate pleomorphism, and the presence of mitotic cells. Repeat magnetic resonance imaging performed a month after the second surgery unexpectedly showed definite tumor enlargement. She remained clinically stable following the third debulking of the tumor and adjuvant radiotherapy. We propose that this recurrent tumor represent malignant transformation from a benign vestibular schwannoma which was an unusual occurrence in a patient without neurofibromatosis.

Neurinoma del acústico: presentación de un caso clínico

El neurinoma del nervio acústico es una neoplasia del ángulo pontocerebeloso con una frecuencia del 6 por ciento de tumores intracraneales y una incidencia de un caso por cien mil individuos al año; no tiene relación con el sexo. Clínicamente se caracteriza por hipoacusia neurosensorial progresiva unilateral acompañada de síntomas auditivos, síntomas trigeminales, diplopía, cefalgias, síntomas de disfunción cerebelosa, aumento de la presión intracraneal, disfunción facial y disfagia. Los exámenes complementarios para definir su diagnóstico incluyen audiometría tonal, prueba de discriminación del habla, potenciales evocados del tronco, tomografía axial computarizada (TAC) y resonancia magnética nuclear con gadolinio...

Neurofibromatosis tipo 2. Alteraciones otoneurológicas: presentación de un caso / Type 2 neurofibromatosis. Otoneurologic alterations: report of a case

La neurofibromatosis tipo 2 (NF2) es un raro desorder autosómico dominante caracterizado por la presencia de neurinomas acústicos bilaterales (schwanomas vestibulares). Se revisan los hallazgos otoneurológicos en un paciente masculino de 48 años de edad que acudió por hipoacusia bilateral de más de ocho años de evolución. El paciente fue sometido a resección completa de la tumoración derecha ante la falta de audición, mejorando de esta manera las alteraciones secundarias debidas a los efectos compresivos

Neurofibromastosis tipo 1 (Enfermedad de Von Recklinghausen): un caso en el Hospital Universitario de Caracas / Neurofibromastosis tipo 1 (Von Recklinghausen disease): a case in the Hospital Universitario de Caracas

La neurofibromatosis es una enfermedad hereditaria en sus dos formas clínicas, NF-1 o enfermedad de Von Ricklinghausen o la NF-2, también llamada neurofibromatosis central. Es importante determinar los diferentes parámetro clínicos para diferenciar ambas entidades que incluyen: La presencia de lesiones cutáneas, déficit neurológicos focales o territoriales, así como la presencia de hipoacusia, este síntoma de vital importancia para el otorrinolaringólogo. En este trabajo presentamos un caso en el Hospital Universitario de Caracas; se presentan resultados de estudios audiológicos tomográficos e IRM; así como anatomo patológicos