Our Management of Vestibular Schwannomas and Review of Literatures

There is no a clear consensus provided in the literature and there remain controversial on the treatment especially for small to medium size Vestibular schwannomas (VSs). Thus the treatment technique and approach preference vary from centre to centre. This problem too exists in our centre. The purpose of this paper is to develop a consensus in our hospital among our colleagues on the treatment of our VSs patients. We have been treating VSs patient by translabyrinthine approach from time to time for the last 5 years and found it to be a very efficient approach. This approach gives the most direct route to the tumor with excellent exposure of the internal acoustic meatus, cerebropontine angle (CPA) area without the need to retract the brain with facial nerve totally in control early in the surgery. The only problem was, when there is large posterior fossa component of the tumor present. This approach is safe with direct exposure to CPA area and have minimum intraoperative or postoperative complications.

Neurofibromatosis tipos 1 y 2 / Neurofibromatosis type 1 and 2

La neurofibromatosis (NF) comprende un grupo de enfermedades genéticas de herencia autosómica dominante, que se clasifican de la siguiente manera: neurofibromatosis tipo 1 (NF1), neurofibromatosis tipo 2 (NF2) y schwannomatosis (también conocida como neurofibromatosis tipo 3). Esta última es una enfermedad muy infrecuente, con una prevalencia aproximada de 1/126 000 personas, por lo que solo profundizaremos las dos primeras. La NF1, también conocida como la enfermedad de Von Recklinghausen, es la más frecuente de las tres y afecta principalmente la piel y el sistema nervioso periférico. Se caracteriza por la presencia de máculas "café con leche", pecas axilares o inguinales, nódulos de Lisch (hamartomas en el iris) y neurofibromas (tumores de la vaina de nervios periféricos). Otras manifestaciones menos frecuentes, aunque de mayor gravedad, incluyen gliomas del nervio óptico, meningiomas, neurofibromas malignos, escoliosis y displasia de la tibia. Su diagnóstico se suele realizar al nacimiento o durante los primeros años de vida, y se estima que un 50% de quienes la padecen presenta dificultades cognitivas. No hay datos concluyentes sobre la mortalidad en los pacientes con NF1, aunque se sabe que la expectativa de vida es menor que en la población general. La NF2 tiene una prevalencia considerablemente menor que la NF1 y su inicio es más tardío, afectando principalmente a adultos jóvenes. La presentación clínica típica se caracteriza por acúfenos, hipoacusia y ataxia en contexto de la presencia de schwannomas vestibulares bilaterales. Otros hallazgos menos frecuentes incluyen schwannomas de nervios periféricos, meningiomas, ependimomas o astrocitomas. La esperanza de vida es de unos 36 años, con una supervivencia media desde el momento del diagnóstico de 15 años. (AU)

Neurofibromatosis (NF) includes a group of genetic diseases with an autosomal-dominant inheritance pattern, and they are classified as follows: Neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2) and Schwannomatosis (also known as neurofibromatosis type 3). This last one is a very rare disease, with an approximate prevalence of 1/126000, so we will only deepen in the first two. NF1, also known as von Recklinghausen disease, is the most frequent, and mainly affects the skin and peripheral nervous system. Its typical manifestations are the presence of café-au-lait macules, axillary or inguinal freckles, Lisch nodules (hamartomas in the iris) and neurofibromas (peripheral nerve sheath tumors). Less frequent manifestations, although more serious, include optic nerve gliomas, meningiomas, malignant neurofibromas, scoliosis and tibial dysplasia. The diagnosis is usually made at birth or during the first years of life, and approximately 50% of patients present cognitive difficulties. There is no conclusive data on mortality in patients with NF1, although it is known that life expectancy is lower than in general population. NF2 has a considerably lower prevalence than NF1, and its onset is later in life, mainly affecting young adults. Its typical clinical presentation is characterized by tinnitus, hearing loss and ataxia in the context in the presence of bilateral vestibular schwannomas. Less frequent findings include peripheral nerve schwannomas, meningiomas, ependymomas or astrocytomas. Life expectancy is about 36 years old, with a median survival from the moment of diagnosis of 15 years. (AU)

Preoperative Identification of Facial Nerve in Vestibular Schwannomas Surgery Using Diffusion Tensor Tractography

OBJECTIVE: Facial nerve palsy is a common complication of treatment for vestibular schwannoma (VS), so preserving facial nerve function is important. The preoperative visualization of the course of facial nerve in relation to VS could help prevent injury to the nerve during the surgery. In this study, we evaluate the accuracy of diffusion tensor tractography (DTT) for preoperative identification of facial nerve. METHODS: We prospectively collected data from 11 patients with VS, who underwent preoperative DTT for facial nerve. Imaging results were correlated with intraoperative findings. Postoperative DTT was performed at postoperative 3 month. Facial nerve function was clinically evaluated according to the House-Brackmann (HB) facial nerve grading system. RESULTS: Facial nerve courses on preoperative tractography were entirely correlated with intraoperative findings in all patients. Facial nerve was located on the anterior of the tumor surface in 5 cases, on anteroinferior in 3 cases, on anterosuperior in 2 cases, and on posteroinferior in 1 case. In postoperative facial nerve tractography, preservation of facial nerve was confirmed in all patients. No patient had severe facial paralysis at postoperative one year. CONCLUSION: This study shows that DTT for preoperative identification of facial nerve in VS surgery could be a very accurate and useful radiological method and could help to improve facial nerve preservation.

Schwannomas vestibulares quísticos / Cystic vetibular schwannomas

Objetivo. Presentar nuestra experiencia en el tratamiento de los Schwannomas vestibulares quísticos comparándolos con lesiones sólidas. Material y método. Se evaluaron en forma retrospectiva los síntomas de presentación clínica, tasas de preservación facial, grado de resección quirúrgica, complicaciones postoperatorias y hallazgos histológicos de los Schwannomas quísticos pareados en base al tamaño tumoral con un grupo de lesiones sólidas. Resultados. Durante el período junio 1995 julio 2010, 27 pacientes con Schwannomas quísticos se operaron en nuestro Departamento. El diámetro promedio fue de 29,6 mm. Los síntomas de presentación clínica más frecuentes fueron la hipoacusia, inestabilidad en la marcha y parestesias faciales. Al año de cirugía, el 74% de los pacientes tenían función facial HB I-III sin diferencias significativas con el grupo de lesiones sólidas. La remoción completa fue 55,5% y 85% de los pacientes en las lesiones quísticas ysólidas respectivamente. Conclusión. Los Schwannomas quísticos deben ser evaluados en forma separada de las lesiones sólidas debido a que pueden crecer rápidamente, presentar mayor complejidad quirúrgica y desarrollar complicaciones postoperatorias con mayor frecuencia.

Objective. To present our experience treating this rare tumor variant.Material and Method. Retrospective evaluation of an institutional cystic vestibular schwannoma series, based on initial symptoms, rate of facial preservation, extent of surgical resection, postoperative complication rate and cystic lesion quantificationon histology in comparison to solid tumor type. Results. During the period June 1995-July 2010, 27 cysticschwannomas were operated on at the FLENI neurological Institute. Mean tumor diameter was 29,6mm. The most frequent presenting symptoms included hypoacusia, unsteadiness and facial paresthesias. One year after surgery, 74% of patients presented facial function HB I-III, showing no statistical difference in comparison to solid lesions. Complete surgical resectionwas possible in 55, 5% of the cystic and 85% of the solid tumor groups, respectively. Conclusion. Cystic vestibular schwannomas should be identified separately from vestibular schwannomas in general, particularlybecause they often undergo more rapid expansion, and may present greater surgical risk as well as higher rates ofpostoperative complications.

Long-term Outcomes of Gamma Knife Stereotactic Radiosurgery of Vestibular Schwannomas

OBJECTIVE: Gamma Knife Stereotactic Radiosurgery (GK SRS) has become an important treatment modality for vestibular schwannomas. We evaluated the tumor control rate, patterns of tumor volume change and preservation of hearing following low-dose radiation for vestibular schwannomas in a homogeneous cohort group in which the mean marginal dose was 12 Gy. METHODS: A total of 59 patients were enrolled in this study. All enrolled patients were followed-up for at least 5 years and the radiation dose was 11-13 Gy. Regular MRI, audiometry and clinical evaluations were done and tumor volumes were obtained from MRI using the OSIRIS program. RESULTS: The tumor control rate was 97%. We were able to classify the patterns of change in tumor volume into three categories. Transient increases in tumor volume were detected in 29% of the patients and the maximum transient increase in tumor volume was identified at 6 to 30 months after GK SRS. The transient increases in tumor volume ranged from 121% to 188%. Hearing was preserved in 4 of the 12 patients who had serviceable hearing prior to treatment. There were no other complications associated with GK SRS. CONCLUSION: Low-dose GK SRS was an effective and safe mode of treatment for vestibular schwannomas in comparison to the previously used high-dose GK SRS. Transient increases in tumor volume can be identified during the follow-up period after low-dose GK SRS for vestibular schwannomas. Physicians should be aware that these increases are not always indicative of treatment failure and that close observation is required following treatments. Unfortunately, a satisfactory hearing preservation rate was not achieved by reducing the radiation dose. It is thought that hearing preservation is a more sophisticated problem and further research is required.

The Causes and Treatment for Cerebrospinal Fluid Leak after Microsurgical Removal of Vestibular Schwannomas / 中国医师杂志

Objective To explore the causes and treatment for cerebrospinal fluid(CSF) leak after microsurgical removal of vestibular schwannomas(VS) with the suboccipital retrosigmoid approach.Methods A retrospective study was accomplished on 258 patients with VS operated through the suboccipital retrosigmoidal approach from Jan 1994 to Aug 2003.After operation,cerebrospinal fluid rhinorrhea occurred in 19 cases and subcutaneous retroauricular CSF leak occurred in 5 cases.Results In 14 cases the CSF leak was stopped after treatment by external lumbar cerebrospinal fluid drainage(CELCFD).Six patients were operated again with sealing the internal acoustic meatus and the mastoid cells with fibrin glue and muscle.The patients were followed up for 14 months to 8 years after treatment,and there was no recurrence of CSF leak or delayed onset meningitis.Conclusion CSF leak was the common complication after vestibular schwannoma removal and the most common reason was the drilled posterior wall of the internal acoustic meatus with opening of the mastoid cells.The closure of petrous air cells was very important to prevent its postoperative CSF leak.Most of the patients were successfully treated by external lumbar cerebrospinal fluid drainage and only a few cases needed revision surgery.