Perfusion-weighted imaging in vestibular schwannoma: the influence that cystic status and tumor size have on perfusion profiles / Perfusão por ressonância magnética em schwannoma vestibular: influência do tamanho e estádio cístico no perfil da perfusão

Abstract Objective: The perfusion profile of vestibular schwannomas (VSs) and the factors that influence it have yet to be determined. Materials and Methods: Twenty patients with sporadic VS were analyzed by calculating parameters related to the extravascular extracellular space (EES)—the volume transfer constant between a vessel and the EES (Ktrans); the EES volume per unit of tissue volume (Ve); and the rate transfer constant between EES and blood plasma (Kep)—as well as the relative cerebral blood volume (rCBV), and by correlating those parameters with the size of the tumor and its structure (solid, cystic, or heterogeneous). Results: Although Ktrans, Ve, and Kep were measurable in all tumors, rCBV was measurable only in large tumors. We detected a positive correlation between Ktrans and rCBV (r = 0.62, p = 0.031), a negative correlation between Ve and Kep (r = -0.51, p = 0.021), and a positive correlation between Ktrans and Ve only in solid VSs (r = 0.64, p = 0.048). Comparing the means for small and large VSs, we found that the former showed lower Ktrans (0.13 vs. 0.029, p < 0.001), higher Kep (0.68 vs. 0.46, p = 0.037), and lower Ve (0.45 vs. 0.83, p < 0.001). The mean Ktrans was lower in the cystic portions of cystic VSs than in their solid portions (0.14 vs. 0.32, p < 0.001), as was the mean Ve (0.37 vs. 0.78, p < 0.001). There were positive correlations between the solid and cystic portions for Ktrans (r = 0.71, p = 0.048) and Kep (r = 0.74, p = 0.037). Conclusion: In VS, tumor size appears to be consistently associated with perfusion values. In cystic VS, the cystic portions seem to have lower Ktrans and Ve than do the solid portions.

Resumo Objetivo: O perfil de perfusão do schwannoma vestibular (SV) não tem sido estudado, nem os fatores que o influenciam. Materiais e Métodos: Vinte pacientes com SV esporádico foram analisados usando Ktrans, Ve, Kep e rCBV e correlacionados com tamanho e estádio cístico. Resultados: Ktrans, Ve e Kep foram medidos em todos os casos. rCBV só foi possível em tumores grandes. Ktrans e rCBV estavam correlacionados positivamente (r = 0,62, p = 0, 0 31 ) . Ve e Kep estavam negativamente correlacionados (r = -0,51, p = 0,021). Ktrans estava correlacionado positivamente com Ve em SVs sólidos (r = 0,64, p = 0,048). Em SVs pequenos, Ktrans foi menor (0,13 vs 0,029, p < 0,001), Kep foi maior (0,68 vs 0,46, p = 0,037) e Ve foi menor (0,45 vs 0,83, p < 0,001) que nos SVs grandes. Ktrans e Ve foram menores dentro dos cistos que nas porções solidas dos SVs císticos (0,14 vs 0,32, p < 0,001; 0,37 vs 0,78, p < 0.001, respectivamente). Foi encontrada correlação positiva em Ktrans (r = 0,71, p = 0,048) e Kep (r = 0,74, p = 0,037) entre as áreas sólidas e císticas. Conclusão: Nos SVs, o tamanho está consistentemente associado com os valores da perfusão. Nos SVs císticos, as porções císticas parecem ter valores menores de Ktrans e Ve do que nas porções sólidas.

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

Abstract 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.

Three-dimensional sampling perfection with application optimized contrasts using different flip angle evolutions sequence in preoperative evaluation of acoustic neuroma / 中国医学影像技术

Objective To investigate the clinical value of three-dimensional sampling perfection with application optimized contrasts using different flip angle evolutions (3D-SPACE) sequence in preoperative evaluation of acoustic neuroma.Methods Totally 57 patients with acoustic neuroma confirmed by surgery and pathology were enrolled.All patients underwent preoperative routine head MR and 3D-SPACE sequence.The position,size and shape of the tumors were observed,and the display rate of surrounding cranial nerves was evaluated with 3D-SPACE sequence.The results were compared with those of conventional MRI and operation.Results All 57 patients were found with single tumor.The tumor in 1 patient (1/57,1.75％) limited in the internal auditory canal,and those in another 56 patients (56/57,98.25％) exceed the internal auditory canal crossing growth.The inner auditory canal fundus in 26 patients (26/57,45.61 ％) were completely filled by the tumors,while those in another 31 patients (31/57) were uncompletely filled.3D-SPACE sequence showed 21 patients (21/57,36.84％) with solid type lesions,35 patients (61.40％,35/57) with solid with cystic type lesions and 1 patient (1/57,1.76％) with cystic type lesion.The coincidence rate of lesion types showed with 3D-SPACE sequence and intraoperative findings was 85.96 ％ (49/57).The display rate of trigeminal nerve internal cisternal segment,lower cranial nerves cisternal segment,abducens nerve cisternal segment,facial nerve internal acoustic meatus segment,facial nerve cisternal segment and acoustic nerve cisternal segment was 100％ (57/57),100％(57/57),75.44％ (43/57),50.88％ (29/57),17.53％ (10/57) and 19.30％ (11/57),respectively,all significantly increased compared with those of conventional MRI (all P＜0.05).Conclusion 3D-SPACE sequence can accurately display the relationship between tumor and adjacent cranial nerves,therefore has important clinical value in preoperative evaluation of acoustic neuroma.

Relationship between clinical characters of acoustic neuroma and cellular immunity / 中国耳鼻咽喉头颈外科

OBJECTIVE To explore the relationship between the clinical characteristics of acoustic neuroma and the number ofT lymphocytes in tumor tissues.METHODS Clinical data of 65 patients diagnosed with VS were retrospectively collected.Peripheral blood samples of the patients were collected and the number of T lymphocytes were counted by flow cytometry.Immunohistochemistry was carried out with the fresh tumor samples compared with 8 normal cranial nerve controls.The expression level of each immune protein was analyzed its correlation with clinical characters was explored.RESULTS The CD3+,CD4+ and CD8+ T lymphocytes in the peripheral blood are not significantly correlated with clinical data.In the tumor tissues,the number of CD4+ and CD8+ T lymphocytes are much larger than those in normal cranial nerves,and negatively correlated with preoperative hearing.The number of CD8+ T lymphocytes has a negative relationship with postoperative facial nerve function.In addition,CD4 and CD8 expression levels in the tumor samples from patients younger than 40 are much higher than those in elder patients.Foxp3 is not detected in the normal cranial nerves.The number of Foxp3+ T lymphocytes is negatively correlated with preoperative hearing.CONCLUSION The CD4+ and CD8+ T lymphocytes mediated cellular immunity play an important role in the development of acoustic neuroma,as well as the reservation and restoration of nerve function.

Retrolabyrinthine approach for cerebellopontine angle region surgeries / 中国耳鼻咽喉头颈外科

OBJECTIVE To evaluate the application ofretrolabyrinthine approach in cerebellopontine angel(CPA) region surgeries.METHODS A total of 42 patients underwent microscopic-endoscopic cooperative surgeries for CPA lesions via retrolabytinthine approach were reviewed.They were hospitalized from January 1st 2011 to January 1st 2016 in our institution.The microscopic-endoscopic technique was applied in all surgeries.RESULTS Complete removal was obtained in all tumor resections and satisfactory symptom-relief was achieved in all microvascular decompressions and neurectomies.In cases with acoustic neuroma and cholesteatoma,useful hearing (AAO-HNS classes A,B and C) was obtained in 66.7％(6/9) patients.No facial paralysis and postoperative complications such as cerebrospinal fluid leakage occurred during follow-up.In cranial nerve rhizopathies cases,complete relief was achieved in all patients.No facial paralysis and other lower cranial nerve dysfunction occurred.CONCLUSION With the preservation of labyrinthine structures,the microscopic-endoscopic cooperative surgeries for CPA lesions via retrolabytinthine approach could increase the hearing preservation level without facial nerve injury.Retrolabyrinthine approach is a good option for cranial nerve rhizopathies and tumors smaller than 15 mm in diameter without involvement of the fundus of internal auditory canal in the CPA region.

Surgical strategy for patients with small acoustic neuroma / 中国耳鼻咽喉头颈外科

OBJECTIVE To summarize surgical treatment effects and to discuss surgical strategy for Small acoustic neuroma.METHODS The clinical data of 26 patients with small acoustic neuroma treated with surgery in our department were analyzed retrospectively.25 patients with preoperative hearing grading of C and D received the labyrinthine approach acoustic neuroma resection,and 1 patient with preoperative hearing grading of B received middle fossa approach acoustic neuroma resection.The preoperative and postoperative hearing level,incidence of tinnitus,balance disturbance and weakness of facial muscles were analyzed retrospectively.The control and recurrence of the tumor,the incidence of complications were recorded.RESULTS Total resection was achieved in 25 cases (96％),and in 1 cases achieved sub total resection due to the fact that the tumor was too adhesive to the facial nerve The follow-up time ranged from 6 months to 7 years with 7 cases lost contact.No deaths nor intracranial infection were encountered.Cerebrospinal fluid rhinorrhea was found in 1 cases after the operation and eustachian tube blockage was performed.All patients(100％) had their facial nerve reserved and 16 patients (88％) had their cochlea nerve reserved.17patients(89.5％) had intact facial nerve function and 2 patients suffered from level Ⅲ facial nerve paralysis (House-Brackmann grade) post operatively.6 patients suffered from vertigo pre-operatively and 5 of them reported disappearance of vertigo after the surgery.Of the 13 patients who did not have vertigo before the surgery,1 patient complained sense of dizziness and unsteady walking post-operatively.5 patients (33.3％) reported disappeared or alleviated tinnitus,8 patients (53％) had the same degree of tinnitus and 2 patients reported worsened tinnitus post-operatively.For patients who did not have tinnitus before the surgery,no tinnitus was reported post-operatively.CONCLUSION treatment strategy for small acoustic neuroma requires personalized setting based on the age of the patient,the combined systemic disease,the severity of the symptoms and the growth rate of the tumor.For patients without practical hearing,the tumor could be removed with labyrinthine approach,and the integrity of the cochlear nerve should be preserved as far as possible,for further reconstruction of hearing ability and cochlear implantation.

Combined application and evaluation of two types of auditory monitoring in acoustic neuroma surgery / 中国耳鼻咽喉头颈外科

OBJECTIVE To explore the significance of intraoperative auditory monitoring(IAMA) in surgery of acoustic neuroma and to compare the value of auditory brainstem response(ABR) and cochlear nerve action potential(CNAP) in auditory monitoring.METHODS Retrospective analysis of 12 cases of acoustic neuroma from January 2016 to December 2016 was performed.All patients have a practical hearing(AAO-HNS,grade class a,b),the ABR waveform can be elicited,wave v differentiation,All tumors were removed via posterior sigmoid sinus approach.RESULTS ABR waveform of all patients were prolonged with different degrees of change(0.68±0.41) ms compared with the preoperative data.Amplitude of CNAP diverse in different individuals,with an average prolong compared to the data before operation(0.25±0.16) ms.In all 12 cases,8 (66.7％) patients remained usable hearing after the operation,4 cases(33.3％) failed to have a usable hearing.Among these 4 patients,3 showed disappearance of wave v,1 patient showed wave v latency prolong in the ABR,meanwhile,2 patients showed P1 dissapear,2 patients showed P1 latency prolong in CNAP.The intraoperative auditory monitoring could play a role in preventing the hearing damage in the procedure.Drilling,noise,surgical nerve stretch or thermal injury may cause the hearing damage.A 5 minutes pause could get some degree of regain,with the amplitude rise again.CONCLUSION A combination use of the ABR and CNAP monitoring has a certain significance in surgery of acoustic neuroma.ABR waveform is stable and reliable,but costs longer time;CNAP stack quickly and improve monitoring sensitivity,but waveform varies.Vibration and noise caused by drilling,nerve stretch during operation and heat damage can be monitored timely.Combined use of ABR and CNAP monitoring can enhance the auditory preservation rate during acoustic neuroma surgery.

Factors of hearing preservation in acoustic neuroma surgery / 中华耳鼻咽喉头颈外科杂志

Over the past 50 years, the focus of acoustic neuroma surgery has shifted from low mortality and tumor resection to retention of neurological function. Hearing preservation is another point in addition to facial nerve function preservation. Hearing preservation rates overall ranged from 2% to 93% in recent studies. Characteristics such as approach, pre-operative neurological function, tumor size, nerve of origin and fundal fluid of the internal auditory canal have been reported as possible influencing factors. This review provides a summary of recent studies and describes the prognostic factors that predict hearing preservation.

Influence of different tumor resection extent on facial nerve function and tumor recurrence in acoustic neuroma surgery / 中国医师进修杂志

Objective To observe the influence of different tumor resection extent on facial nerve function and tumor recurrence in acoustic neuroma surgery.Methods A total of 118 patients with acoustic neuroma operated by the same surgeon from January 2009 to December 2015 were enrolled retrospectively.All patients were treated via suboccipital retrosigmoid transmeatal approach.The neartotal resection strategy was used during operation.Part of the tumors closely adhered to the facial nerveswere not removed forcibly.If there was tumor residue partly,the internal auditory canal was not drilled open.The relationship between facial nerve function or tumor recurrence and tumor resection degree was analyzed.The patients with recurrent tumor were treated with Gamma knife.Results In 118 patients,1 patient (0.8％) died during the operation.The follow-up time ranged from 8-90 months.The total resection rate of acoustic neuroma was 19.5％ (23/118),the near-total resection rate was 74.6％(88/118),and subtotal resection rate was 5.9 ％ (7/118).The recurrence rate was 16.1％ (19/118),in total resection group was 0,in near-total resection group was 15.9％ (14/88),in subtotal resection group was 5/7,there was significant difference (x2 =21.980,P ＜ 0.01).The good rate of facial nerve function after procedure was 90.7％ (107/118),in total resection group was 73.9％ (17/23),in near-total resection group was 95.5 ％ (84/88),in subtotal resection group was 6/7,and there was significant difference between total resection group and near-total resection group (x2 =14.168,P ＜ 0.05).After Gamma knife treatmentthe tumor volume increased again in 3 patients (2.5 ％) during the follow up period,and they were reoperated.Conclusions After near-total resection of acoustic neuroma,the assisted Gamma knife therapy may effectively control the growth of acoustic neuroma,and significantly improve the retention rate of facial nerve function.For the improvement of the quality of life,it is a feasible treatment scheme in the patients with tumors closely adhered to the facial nerves.

The facial nerve functional recovery law and tumor size impact after acoustic neuroma surgery / 天津医药

Objective To explore the facial nerve functional recovery law after resection of acoustic neuroma,and the influence of tumor size on postoperative facial nerve function. Methods According to the House-Brackman (HB) facial nerve function classification method, 89 patients with acoustic neuroma were performed microsurgical resection with the ret?rosigmoid approach and facial nerve preservation. The HB classification method was used to evaluate the facial nerve func?tion at operation, 15 d, 45 d, 3 m, 6 m, 12 m and more than 12 m after surgery. The recovery pattern of neurological function after operation was analyzed. al. According to the tumor size, patients were divided into three groups: diameter < 30 mm group (n=23), 30-40 mm group (n=31) and≥40 mm group (n=35). The facial nerve function was compared between different groups with early postoperative (within 15 days) and long-term (more than 12 months). Results The facial nerve function was the worst in 15 days after operation (excellence rate was 52.81%), but the function was returned to normal in postopera?tive 3 months (excellent rate reached 80.90%). After postoperative 12 months, almost all patients returned to normal func?tion (excellent rate was 91.01%), and the facial nerve recovery was more smoothly (excellent rate was 92.13%). Tumor size had remarkable effect on facial nerve function in the early postoperative period (χ2=23.34, P<0.05), and long-term period (χ2=14.46, P<0.05). And tumor size was positively correlated with classification of facial nerve function in the early stage (r=0.476, P<0.05) and long-term stage (r=0.379, P<0.05). The excellent rates of postoperative facial nerve function were decreased with the increased diameters of tumor size. Conclusion The facial nerve function may appear deterioration in early postoperative period (within 15 days) in patients with acoustic neuroma, which can return to the normal level in 12 months. The diameter of tumor is one of important factors influencing the early and long-term prognosis of postoperative fa?cial nerve function.

Far Infrared Thermography Analysis with Acoustic Neuroma / 中国医学影像学杂志

PurposeTo analyze the far infrared thermography characteristics before and after surgery in patients with acoustic neuroma.Materials and Methods Thirty-two patients with acoustic neuroma were included as observation group and 40 normal healthy individuals as control group. Un-cooled thermal imaging system (ATIR-M301B) was used with working temperature of 20-25℃. Craniofacial infrared images were collected to analyze temperature differences among different detection zones.Results Far infrared thermography revealed that there were no obvious temperature differences between both sides of supraorbital region, endocanthion region, frontal region and buccal region in the control group (P>0.05). The temperature differences in bilaterally symmetrical parts of supraorbital region, endocanthion region, frontal region, buccal region were significantly higher in observation group (t=1.557, 1.714, 1.483 and 1.569,P<0.05). The craniofacial temperatures of 32 patients changed after operation, and the differences reduced in supraorbital region, endocanthion region, frontal region, and buccal region (t=2.655, 2.462, 2.897 and 4.465,P<0.05).Conclusion Far-infrared thermography inspection can detect abnormal temperature changes.

Facial reanimation by hypoglossal-facial neurorrhaphy

Objective: Facial palsy may still occur after removal of large vestibular schwannomas. The aim of this paper is to describe the outcome of patients submitted to facial reanimation and make a concise revision about modern techniques available to reanimate a paralyzed face. Methods: A retrospective study of was performed about the surgical results of 12 patients submitted to hypoglossal-facial neurorrhaphy. These patients were submitted to radical removal of large vestibular schwannomas (> 3 cm) before and anatomic preservation of the facial nerve was not possible. Results: In 10 cases (83%) patients had a good outcome with House-Brackmann facial grading III. In two other cases the facial grading was IV and VI. All patients were follow-up for at least one year after the reanimation procedure. Conclusion: Hypoglossal-facial neurorrhaphy is a very useful technique to restore facial symmetry and minimize the sequela of a paralyzed face. Long last palsy seemed to be the main reason of poor outcome in two cases...

Paralisia facial pode ocorrer após remoção de schwannomas vestibulares volumosos.Neste artigo é descrito o resultado obtido em pacientes submetidos à reanimação facial, bem comoé realizada uma revisão concisa das técnicas modernas disponíveis para reanimação de uma faceparalisada. Métodos: Estudo retrospectivo do resultado cirúrgico de 12 pacientes submetidos àneurorra&a hipoglosso-facial. Todos esses pacientes foram operados anteriormente de schwannomasvestibulares volumosos (> 3 cm) e não foi possível a preservação anatômica ou funcional do nervofacial. Resultados: Em 10 casos (83%), observou-se boa recuperação da paralisia e gradação &nal IIIna escala de House-Brackmann. Em dois outros casos, um paciente evoluiu com grau IV e outro comgrau VI. Todos os pacientes foram seguidos por pelo menos um ano após o procedimento. Conclusão:A neurorra&a hipoglossal-facial é uma técnica útil para restaurar a simetria facial e minimizar as sequelasde uma face paralisada. Paralisia de longa duração foi a causa de insucesso em dois casos nesta série...

A Case of Gastric Cancer Manifesting as a Solitary Brain Metastasis in the Cerebellopontine Angle That Mimicked Acoustic Neuroma / 전남의대학술지

At the time of diagnosis, about 20% of patients with gastric cancer have stage IV disease involving the liver, lung, and bone. Brain metastasis from gastric cancer is exceedingly rare, with an incidence of <1% of clinical cases. A 59-year-old man was admitted with hearing loss in the left ear and left facial palsy for 1 month. A magnetic resonance imaging scan revealed a tumor in the cerebellopontine angle that extended to the inner auditory canal and that was clinically diagnosed as acoustic neuroma. After complete resection, histological examination showed metastatic poorly differentiated carcinoma. Further investigation revealed advanced gastric cancer involving the antrum with no evidence of the involvement of other sites except the brain parenchyma. Palliative total gastrectomy was performed and the surgical specimen revealed a poorly cohesive carcinoma that was histopathologically identical to that of the resected brain tumor. Here we report this rare case of gastric cancer that initially presented as a solitary brain metastasis mimicking acoustic neuroma.

A Case of Gastric Cancer Manifesting as a Solitary Brain Metastasis in the Cerebellopontine Angle That Mimicked Acoustic Neuroma / 전남의대학술지

At the time of diagnosis, about 20% of patients with gastric cancer have stage IV disease involving the liver, lung, and bone. Brain metastasis from gastric cancer is exceedingly rare, with an incidence of <1% of clinical cases. A 59-year-old man was admitted with hearing loss in the left ear and left facial palsy for 1 month. A magnetic resonance imaging scan revealed a tumor in the cerebellopontine angle that extended to the inner auditory canal and that was clinically diagnosed as acoustic neuroma. After complete resection, histological examination showed metastatic poorly differentiated carcinoma. Further investigation revealed advanced gastric cancer involving the antrum with no evidence of the involvement of other sites except the brain parenchyma. Palliative total gastrectomy was performed and the surgical specimen revealed a poorly cohesive carcinoma that was histopathologically identical to that of the resected brain tumor. Here we report this rare case of gastric cancer that initially presented as a solitary brain metastasis mimicking acoustic neuroma.

Application of intraoperative neurophysiological monitoring for the large acoustic neuroma / 肿瘤研究与临床

ObjectiveTo explore the function of intraoperative monitoring by brainstem auditory evoked potential and free electromyography during the operation of large acoustic neuroma for improving the operation more accurately and safely. MethodsThe intraoperative monitoring of affected cranial nerve and brainstem function respectively by brainstem auditory evoked potential and free electromyography was performed in 26 patients with large acoustic neuroma. According to the monitoring result the strategy and method of surgery was adjusted. Facial nerve function was assessed using the House-Brackmann facial nerve grading system immediately after two weeks of surgery.Results23 cases (88 ％) achieved total resection,3 cases(12 ％)achieved subtotal resection. The facial nerve was preserved anatomically in 25 patients.According to the House-Brackmann facial nerve grading system,21 cases (80 ％) got preserve of facial nerve function in grade Ⅰ - Ⅱ, 3 cases(12 ％)got preserve of facial nerve function in grade ]Ⅲ-Ⅳ and 1 cases (4 ％) got preserve of facial nerve function in grade Ⅴ after two weeks of surgery.ConclusionIntraoperative physiological monitoring may increase the anatomical and functional preservation rate of affected cranial nerve and also may improve the operation more accurately and safely.

Microsurgery for acoustic neuroma and the facial-acoustic nerve protection / 中国基层医药

Objective To explore the protection of the facial-acoustic nerve during microsurgery for acoustic neuroma via the suboccipital retrosigmoid approach. Methods The clinical data of 25 cases with acoustic neurinoma treated by the suboccipital retrosigmoid approach were retrospectively analyzed. Results Total removal was achieved in 22 patients and subtotal in 3 patients. 20 with Cochlear nerve anatomic preservation at 2 weeks after surgery and 3 patients with effective hearing and 13 patients lost effective hearing but retained measurable hearing and 9 patients completely lost hearing( the New Hannover Classification V grade). The facial nerve was preserved anatomically in 18,H-B Grade I ～ IV in 15,Grade V ～ VI in 10. There were not cerebrospinal fluid leakage, intracranial infection and death in all cases. Conclusion When operating,the relation between the tumor and the important structure surrounding could should be understood fully. Then removed the tumor piece by piece with microsurgical techniques. That the effective way to keep the facial nerve and its function being protected,and could improve the prognosis of the operation.

Endoscope-assisted lateral skull base surgery / 中国医师进修杂志

Objective To explore the therapeutic efficacy and complications of endoscope-assisted lateral skull base surgery. Methods Assisted by hard-tube ear endoscope, 11 patients with acoustic neuroma were operated via labyrinthine approach and retrosigmoid approach, and 5 patients with petrous apex cholesteatoma were operated via middle cranial fossa approach and mastoid-middle cranial fessa approach. Results Among 11 patients with acoustic neuroma, total removal was achieved in 9 cases (81.8%), subtotal in 2 cases (18.2%). Facial nerves and cochlear nerves were preserved completely during operation. After operation there was no facial paralysis in 9 cases (81.8%), mild peripheral facial paralysis in 2 cases (18.2%), the same hearing level as that of preoperation in 2 patients (18.2%), hearing impairment in different degrees in 9 cases (81.8%), among which moderate sensorinural hearing loss in 1 patient (9.1%), moderate to severe in 2 patients (18.2%), severe in 3 patients (27.3%), profound in 3 patients (27.3%). Among 5 patients with petrous apex cholesteatoma, total removal was achieved in all cases. After operation, preoperative facial paralysis in 3 patients disappeared within 9 months, and moderate to severe conduction deafness appeared in 2 patients. Conclusions The application of ear endoscope in lateral skull base surgery can improve the total removal of lesions and the salvage rate of vessels and nerves. However, its disadvantages make it only be an assistant method for micresurgery.

Experimental study on the relationship between F wave recording, facial nerve function and its pathological changes in the pressure-induced rat model of acoustic neurinoma / 肿瘤研究与临床

Objective To explore the value of F wave recording in evaluating facial nerve function and its pathological changes in the pressure-induced rat models of acoustic neurinoma. Methods 58 rats in different groups were conducted F wave recording and biotinylated dextran amine(BDA) retrograde tracing for their right facial nerve one week after establishing models. Their latencies, amplitudes and F/M rates were analyzed first. 72 hours after BDA was injected into right whisker muscle, the rats were infused with 4% polyoxymethylene, then pontines and facial nerves in the CPA cistern were obtained. Pontiues were cut into frozen sections for histochemical staining with avidin-horseradish peroxidase (HRP)-DAB and Nissl 's counterstaining, calculating the positive BDA neurons ratio(BDA+-N%)in facial nuclear. Facial nerves were cut and stained with toluidine blue for light-micrescope inspection, and/or stained for transmission electron microscope observation. Correlating F/M with BDA+-N% and the facial nerve pathological findings. Results F/M are 97.66 % and 97.48 % in normal and pseudo-operation group, respectively, when stimulus are 1.4 mA; while 77.13 %, 48.91% and 11.54 % in from small to large tumor model groups because F waves were delayed in latencies or increasinglylost (P <0.001). Similarly, BDA+-N% are 98.37 % and 97.96 % in the above two control groups, while 77.28 %, 48.28 % and 11.55 % in from small to large tumor model groups (P < 0.001). Thus F/M are positively correlated with their BDA+-N% in all groups (r =0.996,P <0.001). Facial nerve examinations under light and electron microscope show increasing pathological changes along with increasing "tumor" size. Conclusion The findings of F wave recording in facial nerve may reflect its functional status and pathological changes. Therefore, F wave detection may help electrophysiological monitoring during acoustic neurinoma resection and facial nerve function evaluation after surgery.

MICROSURGICAL ANATOMY OF THE ANTERIOR INFERIOR CEREBELLAR ARTERY / 解放军医学杂志

The anatomy of the trunks and branches of anterior inferior cerebellar artery(AICA) was studied and its surgical importance especially in the operation for acoustic neuroma(AN), was discussed.15 fresh adult cadavers were perfused with ABS via internal carotid artery and vertebral artery and then dissected under operation microscope in detail. AICA was constantly present in all specimens. The incidence of labyrinthine artery(LA), recurrent perforating artery(RPA), subarcuate artery(SA),and cerebellar subarcuate artery (Cer.SA) was 100%,86.7%,80% and 16.7%, respectively. 97.1% of LA entering the internal auditory meatus (IAM) were located under the facial vestibulocochlear nerve complex, 56.7% of RPA passed between it ,and 75% of SA was located posteroinferiorly to it .60.7% of the loop of AICA was situated close to the IAM, and 53.6% of them lay between the Ⅶ and Ⅷ cranial nerves. These data may be helpful in microneurosurgical operation and radiography.

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.