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A 64-year-old woman was affected with sudden bilateral hearing loss. She initially visited us complaining of right-sided accordingly hearing loss, which was diagnosed as right sudden deafness, and treated. Thereafter she indicated that vertigo, with right tinnitus, had increased. She was subsequently diagnosed with Meniere's disease. Thereafter she visited us complaining of left-sided hearing loss. After numerous clinical visits and extensive examinations, including MRI, she was diagnosed as having a bilateral acoustic tumor, although she didn't have the cafe-au-lait spots, induration under the skin, or small nodules of the iris and juvenile cataractas that are characteristic of Recklinghausen's disease. As her symptoms were atypical and the course of her disease was unusual for patient affected with an acoustic tumor in consideration of her age, we didn't recommend surgery. Presently she uses a hearing aid in the left ear.

The effects of relatively low dose Gamma Knife irradiation on acoustic schwannoma were evaluated in 29 patients followed over 2 years after treatment. The mean dose delivered to the tumor periphery was 12.1 Gy. Lowering of the magnetic resonance signal intensity in the tumor center appeared in 69% and signs of tumor shrinkage appeared in 59% of cases. The cyst in the tumor enlarged in 3 cases, and 2 cases developed hydrocephalus. The percentage of pure-tone hearing preservation was 82% at 3 months, 73% at 6 months, 68% at 12 months. 64% at 18 months and 59% at 24 months in 22 out of 29 cases. Relatively low dose Gamma Knife radiosurgery was effective in suppressing tumor growth, with preservation of hearing.

Sound lateralization is considered useful in diagnosing retrocochlear lesions. Interaural time difference (ITD) discrimination has been considered more important than interaural intensity difference (IID) discrimination in diagnosing retrocochlear lesions. The purpose of this study was to determine whether testing sound lateralization by IID and ITD discrimination is useful in patients with acoustic neurinomas (AN). Twenty patients (15 to 74 years old) with unilateral AN were studied by testing IID and ITD discrimination using a self-recording device by delivering 500 Hz band noise through head-phones. Auditory brainstem response (ABR) testing and magnetic resonance imaging (MRI) were also performed in all patients. IID discrimination abnormalities were found in 25% of all patients, and ITD discrimination abnormalities in 85%. Five patients (25%) showed both IID and ITD discrimination abnormalities. One of the three patients with both normal IID and ITD discrimination showed waves I and V, and two of them showed waves I, III and V. One of the five patients with both IID and ITD discrimination abnormalities showed no response, two of them showed only wave I, the other two showed waves I, III and V. Two patients with latency prolongation between waves III and V had both IID and ITD discrimination abnormalities, and seven patients with latency prolongation between waves I and III had normal ITD discrimination or slightly abnormal ITD discrimination and normal IID discrimination. Three of the four patients with large tumors (> 3 cm) had both IID and ITD discrimination abnormalities, while two patients with small ear tumors (< 1 cm) had both normal IID discrimination and normal ITD discrimination. Normal ITD discrimination or slightly abnormal ITD discrimination was found in the majority of patients with wave III. Impairment of ITD discrimination was well correlated with wave III abnormalities. Patients with latency prolongation between waves III and V showed a high degree of ITD discrimination abnormality. Impairment of IID discrimination was related to a high degree of cochlear nerve damage or brainstem damage. We emphasize that IID discrimination is important in the neurological diagnosis of AN, in addition to ITD discrimination. Sound lateralization testing was a useful screening test for diagnosing AN, because tumor size influenced lateralization in every patient, and ITD discrimination was closely correlated with the ABR findings.

Single photon emission computed tomography (SPECT) was performed on 16 patients with acoustic neurinoma before and 1 and 2 years after Gamma Knife surgery. 201T1C1-SPECT was used to determi

A case of multiple neurilemmoma in the cauda equina, the posterior mediastinum and peripheral nerves is reported. A 24 year old male presented with gait disturbance and muscle weakness in the lower extremities. His past history included the presence of multiple neurilemmomas in the left upper extremities.Myelography and MR imaging showed tumors in the intradural space between the thoracic level and the sacral level. All resected tumors showed the same pattern of Antoni A tissue and Antoni B tissue. In comparing this patient with neurofibrolmatosis type 2, we conclude that the diagnosis of this patient is neurilemmomatosis and not neurofibromatosis because of the absence of cardinal features of neurofibromatosis. Patients with neurilemmomatosis should be carefuly observed for the development of other neuro mas such as acoustic neurinoma.

Ten patients (5 male, 5 female) with acoustic neurinoma underwent stereotactic radiosurgery with a gamma unit. Their ages ranged from 29 to 68 years (mean, 52 years). The follow-up periods were 20 to 38 months (mean, 26 months). The doses delivered to the tumor were 9.9 to 13.5 Gy at the periphery and 17 to 30 Gy at the center. Neuroimaging studies showed that 6 tumors became smaller, 3 were unchanged, and 1 was larger. Severe complications such as hydrocephalus were not seen. Hearing was presereved with a change in the pure tone audiometric threshold of 10 dB or less in 6 of the 8 patients tested. One patient became deaf 5 months after surgery. His CT scan had shown large cysts in the tumor before surgery. Indications for this type of therapy for such patients must be decided cautiously.

Gross intratumoural haemorrhage in acoustic neurinoma is rare. The authors describe seven patients, out of a consecutive 99 cases of acoustic neurinoma operated by the first author, who presented with haemorrhage. Risk factors for haemorrhage appear to be large size, mixed Antoni type and secondary vascular changes.

Thirty-seven patients with acoustic neurinoma were analyzed clinically, 20 males and 16 females, 27 to 71 years of age (average 49.4).The sizes of the tumors ranged from intrameatal to 60mm in diameter.Hearing loss or tinnitus were the chief complaint of all patients, and seven complained of dizziness.There was no correlation between tumor size and hearing level, frequency or duration of distress.Abnormal test results were auditory brain stem response (ABR) and caloric nystagmus in many patients.Five patients with tumors larger than 30 mm showed abnormal equilibrium test results (OKN, ETT etc.), but none of the other patients did.Conventional X-rays (Stenver's projection) showed an enlarged internal auditory canal in 20 pa-tients (54%).There are no typical symptoms of acoustic neurinomas, but unilateral sensorineural hearing loss, tinnitus, diminished caloric response, widening of the internal auditory canal on plain X-rays were found to be useful parameters in the screening process.ABR and Gd-enhanced MRI is the most useful and reliable examination for the diagnosis of acoustic neurinoma in the early stage.

The effectiveness of stereotactic gamma-radiosurgery for treating acoustic neurinoma was evaluated by measuring the volumes of the tumor, non-enhanced tumor, and cerebellar edema in 13 patients with acoustic neurinoma who were followed up for 9 to 15 months (median 12.7 mos) after treatment. The tumor volume and non-enhanced volume tended to reach a maximum after 6 months, and cerebellar edema volume after 9 months, then decreased gradually thereafter. Hearing loss tended to increase gradually, but involvement of the facial nerve was transient.

Angular acceleration of head movement was measured during stepping in patients with unilateral vestibular disorder (acoustic neurinoma before surgery (pre-AT), 10; acoustic neurinoma after surgery (post-AT), 9; acute peripheral vestibular disorder (APVD), 4).1) In patients with post-AT or APVD, the amplitude of specified angular acceleration toward the affected side was significantly higher than that toward the normal side.2) The amplitude of specified angular acceleration showed a negative correlation with the degree of CP (canal paresis) on the calorigram in patients with pre-AT, but a positive correlation in those with APVD.3) The amplitude of specified angular acceleration showed a negative correlation with the degree of DP (directional preponderance) in Barany's rotation test in all the patients.4) These findings suggest that the function of the semicircular canals and compensation by the vestibular spinal reflex in patients with unilateral vestibular disorder can be detected by measuring the specified angular acceleration during stepping.

Preoperative and postoperative vestibular function was determined in 9 patients with acoustic neurinoma treated by stereotactic radiosurgery with a gamma unit at Tokyo University Hospital. All of the patients had good vestibular function (CP

Vestibular symptoms before and after removal of acoustic neurinoma were studied in 47 patients in relation to the origin and size of the tumor and the caloric response. Vertigo and/or dizziness had been noted preoperatively in 26 of the 47 patients (55%). The incidence of such vestibular symptoms was significantly higher when the tumor originated in the superior vestibular nerve (SVN) than when its origin was the inferior vestibular nerve (IVN). No significant difference was seen in relation to tumor size. In patients with a small acoustic tumor or a normal caloric response preoperatively, postoperative vertigo tended to be prolonged. In 9 patients who were operated on through a middle cranial fossa approach, the duration of vertigo after surgery was analyzed further in relation to preservation of the remaining vestibular nerve. When tumors were IVN origin, postoperative vertigo lasted longer when the SVN was resected than when it was those preserved.

Twenty three patients of acoustic tumors treated with gamma knife were evaluated during follow-up period ( mean 16 months, 6 months to 25 months ). The tumors became to decrease in size 1 year after gamma knife surgery more than 50% of all tumors. Hearing preservations were performed 73% of patients with preoperative hearing level, and 100% of the patients with hearing in class 1 or 2 of House and Brackmann classification before gamma knife surgery. One patient developed mild facial paresis and 1 patient had hydrocephalus successfully treated with V-P shunt operation. These low complications may lead conclusion that gamma knife surgery is effective alternative therapy for small to mediam sized acoustic neurinoma.

A 46-year-old woman complained of discomfort of the left side of her tongue. Six months later, she complained of a subjective loss of speech discrimination on the left side, but hearing loss was not seen on a pure-tone audiogram. One year later, a C-P angle tumor was found by MRI and a dip of 500 Hz was seen on her audiogram. At that time, she complained of numbness around the left corner of her mouth and discomfort of the left side of her face. However, the internal acoustic meatus was not enlarged on plain craniograms or a CT scan. During the course of her illness, the woman did not complain of tinnitus, and nystagmus was not observed either through Frenzel's glasses or by electronystagmography.We conclude that, although there was no tumor in the internal acoustic meatus, the brain stem may have been compressed by the tumor with cyst formation, thereby causing such atypical symptoms and clinical course.This case emphasizes 'the importance of recognizing the neurological relationship between hearing loss and other cranial nerve symptoms.

Of 200 patients with acoustic neurinoma undergoing an operation via the retrosigmoid transmeatal approach in the semisitting position, 18 patients had a high jugular bulb on the tumor side. The frequency was 9%. From a neurosurgical point of view, a jugular fossa above the low border of the internal auditory canal (IAC) is classified as a high one. All 200 patients were evaluated by computed tomography with bone window reconstruction of high-resolution thin axial slices (1.5 mm). High jugular bulbs were classified into three grades as follows: Grade I, jugular bulb situated less than 1.5 mm above the low border of IAC; Grade II, jugular bulb between 1.5 and 3.0 mm above the low border of the IAC; Grade III, jugular bulb > 3 mm above the low border of IAC. There were eight patients with Grade I, six patients with Grade II, and four patients with Grade III. In these patients, in order to open the IAC without concomitant injury of the jugular bulb, the superior posterior portion of the porus was drilled away. Opening the jugular fossa was unavoidable in Grade III cases. No difference was noted in functional preservation of facial or cochlear nerve between HJB cases and normal jugular bulb cases, but HJB cases had a higher frequency of air embolism during tumor removal than did normal cases (16 versus 5%), especially Grade III cases (two of four). There was no mortality or morbidity in the cases of air embolism. Details of the surgical procedure in such cases are discussed.

A case of cavernous hemangioma in the internal auditory canal was reported. The chronology of this case was similar as one of Ménière's disease. The neurotological findings in this case were no specific findings to differentiate cavernous hemangioma from acoustic neurinoma. The high-resolution computed tomography (HRCT) revealed calcium stippling in the lesions, whereas magnetic resonance imaging (MRI) demonstrated a low signal intensity on both T1- and T2-weighted images. Comparison of HRCT and MRI findings is most useful for differential diagnosis of intracanalicular tumors.

Resumen Desde Septiembre de 1976 hasta Febrero de 1990 se han tratado 30 pacientes afectos de una paralisis facial periferica yatrogena secundaria a la actuacion neuroquirurgica en el angulo pontocerebeloso o a cirugia de la glandula parotida practicandoseles una anastomosis hipogloso-facial que se complemento con la hipoglosohipogloso en un 43,33% de los casos. Los pacientes se distribuyeron en dos grupos: anastomosis precoces y tardias, constatandose en el grupo de las primeras un 61,54% de reinervaciones excesivas, y en las segundas un 94,12% de resultados buenos y excelentes. En este estudio se analizan y discuten estos resultados.

Other names: central neurofibromatosis; bilateral acoustic neurofibromatosis; bilateral acoustic neurinoma; bilateral acoustic schwannomas. Inheritance: autosomal dominant with almost complete penetrance; frequency is 3/10 newborns; neomutation represent 50% of cases; variable expressivity from mild disease through life (Gardner type) to severe condition at young age (Wishart type: with more than 3 tumours).

Objective: Auditory disorders of the contralateral ear in patients with unilateral acoustic neurinoma have previously been reported using the auditory brainstem response. From our survey of the literature, there is no reported result about electrocochleography (ECoG) in the contralateral ear of acoustic neurinoma cases. In the present study, we reported ECoG and pure-tone audiometric results of the contralateral ears in cases of unilateral acoustic neurinoma and the relationship between ECoG findings and tumor size was discussed. Methods: ECoG and pure-tone audiometry were performed for the contralateral ears in 27 cases of unilateral acoustic neurinoma, and the relationships between tumor size and contralateral ECoG findings and between pure-tone threshold and ECoG findings were investigated. As for ECoG findings, the negative summating potential to the compound action potential ratio (–SP/AP ratio) was examined. The tumor size was assessed by magnetic resonance imaging. Results: Abnormal –SP/AP ratio exceeding 0.40 of the upper limit of the normal range was found in 7 (25.9%) of 27 ears. Incidences of abnormal –SP/AP ratio were 30.0% in large tumors (n = 10), 33.3% in mid-size tumors (n = 6) and 18.2% in small tumors (n = 11). There was no correlation between the incidences of abnormal –SP/AP ratio and tumor size. Moreover, there was no correlation between the –SP/AP ratio and pure-tone threshold at the ECoG recording. Conclusion: These results suggest that any size of acoustic neurinoma may affect contralateral electrocochleographic findings. One possible cause may be dysfunction of the olivocochlear efferent system and another may be endolymphatic hydrops (e.g. delayed endolymphatic hydrops). Currently, however, the causes of –SP/AP ratio increase are still unknown and further investigations are required.

Conclusion: Evoked oto-acoustic emission (EOAE), in particular the slow component, is fragile with the inner ear lesions and is apt to disappear in impaired ears. This presence is thought to mean that inner ear is not badly damaged, and that the presence of EOAEs in early stage sudden deafness carries a good prognosis. Narrow-band EOAE analysis would open a potentially promising way to manage sensorineural deafness. Objective: The aim of present study was to evaluate the characteristics of EOAEs from pathologic ears by a narrow-band EOAE analysis, which allowed us to investigate amplitude, frequency content and latency of EOAEs simultaneously and also to easily detect weak echoes in cases with inner ear lesions. Materials and Methods: EOAEs were analyzed by investigating narrow-band frequency contents of EOAEs, filtered by a 100-Hz step of pass bandwidth in frequency regions from 1.0 to 2.0 kHz, and by 500 Hz of pass bandwidth in the frequency ranges of 0.5–1.0 and 2.0–5.0 kHz. EOAE testing was performed in 40 normal ears and 111 ears with pathologic disorders, including sudden deafness, Ménière’s disease and surgically proven acoustic neurinomas. Spontaneous oto-acoustic emission was investigated in some cases. In acoustic neurinoma, especially computed tomography scan and magnetic resonance imaging tests were performed to assess the tumor size. Results: (1) Narrow-band EOAE analysis revealed that EOAEs from normal ears were composed of two main echo trains and several sub-echoes. The main echo trains were divided into a fast component with a short latency of 10 ms. (2) EOAEs could often be detected from ears with moderate to severe hearing loss >45 dB HL in early stage sudden deafness. The prognosis of sudden deafness was good in cases where both a fast component and slow component were detected in the acute stage within 2 weeks after the deafness onset, and was pessimistic, when either or both of them failed to recover. (3) In Ménière’s disease, EOAE was found in 6 (40%) of 15 cases with hearing loss >50 dB, and detected in 54 (90%) of 60 cases with slight to moderate deafness

Subarachnoid haemorrhage (SAH) of the posterior fossa in cases of acoustic neurinoma is very rare. The authors present the clinical, neuroradiological and histological findings of an acoustic neurinoma presenting with SAH. The literature regarding this subject is reviewed and the pathogenesis of haemorrhage from neurinoma is discussed.

The authors have reviewed hearing results obtained in 99 patients operated on via the suboccipital approach for acoustic neurinoma, who were not deaf prior to surgery (pure tone average less than 70 dB). Tumor size was less than 10 mm in four cases, 10 to 19 mm in 26 cases, 20 to 29 mm in 39 cases, and 30 mm or greater in 30 cases. Removal was macroscopically complete in 92 cases and incomplete in seven, including four cases with bilateral acoustic neurofibromatosis. Hearing was preserved in 29 patients (29.3%), of whom 23 had neurinomas smaller than 30 mm and six had tumors exceeding 30 mm in size. Postoperative hearing was good in eight cases (four with neurinomas less than 20 mm and four with neurinomas greater than 20 mm), serviceable in four cases (three with neurinomas less than 20 mm and one with a tumor greater than 30 mm), and poor in 17 cases (eight with neurinomas less than 20 mm and nine with tumors greater than 20 mm). Fifty-seven patients underwent intraoperative brain-stem auditory evoked potential monitoring: the rate of hearing preservation was found to be higher in this group than in the 42 without monitoring (p less than 0.05). A statistical study using stepwise regression analysis showed that the two preoperative factors most significantly associated with postoperative hearing preservation are a good auditory level for low frequencies measured by pure tone audiometry and a small-sized tumor. Overall results indicate that, even if hearing is more easily preserved when the neurinoma is small and the preoperative auditory condition is good, the surgeon should try to save hearing in all patients who have preserved hearing before surgery.

Five cases of unilateral dilatation of the internal auditory canal with positive neuro-otological findings are presented. Acoustic neurinoma was ruled out by MRI or CT.The unilateral dilatation of the internal auditory canal was thought to due to so-called patulous canal in one patient and to neurofibromatosis in one. It appeared to be a normal variant in three patients. In patient with a patulous canal, there was ballooning of the internal ear canal. The causes of the ipsilateral positive neuro-otological findings were unknown.Undoubtedly, temporal bone tomography and neuro-otological examinations play important roles in the diagnosis of acoustic neurinoma, but we should consider the possibility of misdiagnosis due to false positive results of these examinations. The final diagnosis of acoustic neurinoma must rely on MRI findings.

We reported a case of diffuse metastatic leptomeningeal carcinomatosis (DMLC) with vertigo and hearing loss as early symptoms. From the examinations of a hearing test, internal auditory meatus tomography, caloric test, and auditory brain stem response, acoustic neurinoma was suspected firstly, and was ruled out finally by differential diagnosis. No remarkable findings were revealed in either CT or MRI and the cytological examination of cerebrospinal fluid showed many atypical cells, and the final diagnosis was DMLC. We made some discussions on this case and other cases reported in the literature.

Resumen Exponemos nuestra experiencia en el tratamiento de los neurinomas del acustico con radiocirugia, mediante un aparato de telecobaltoterapia (Theraton 80), acoplado a un sistema de esterotaxia, en cinco pacientes ancianos, cuya edad promedio fue de 70 anos. Todos ellos presentaban patologias graves asociadas que impedian el tratamiento quirurgico. El diametro promedio del tumor era de 21 mm. Se administro radioterapia (Radiocirugia), con una dosis promedio de 2.770 cGy (rango 2500 a 3750 cGy) en una sola sesion, mediante un promedio de 17,8 campos isocentricos con un colimador de 20 mm. de diametro. La reparticion de la isodosis se hizo de la siguiente manera: en los casos 2 y 4 el 90% de la isodosis alcanzo la periferia del tumor, en el caso 5 el 80%, en el caso 3 el 40%, mientras que en el caso 1, solo el 20% de la isodosis alcanzo la periferia del tumor. La radiacion fue bien tolerada por todos los pacientes. La TAC de control puso de manifiesto la disminucion del tamano de la lesion en 3 pacientes y la aparicion de una zona hipodensa central en 2. Un paciente desarrollo hidrocefalia y radionecrosis de cerebelo que preciso derivacion del LCR y tratamiento con corticoides. Dos pacientes tuvieron una buena recuperacion, otro tenia una moderada incapacidad y 2 se han estabilizado, pero son incapaces de valerse por si mismos, dependencia que ya la tenian. Consideramos que la radiocirugia estereotaxica empleando cobalto 60 (Co 60), es una alternativa a la extirpacion quirurgica o a la simple observacion clinica y tomodensitometrica, en pacientes ancianos o con patologias graves asociadas.

Gross intratumoral haemorrhage is rare in vestibular schwannomas. The authors describe the clinical features of this entity in 6 patients, the histopathologic findings in 5 of them, and discuss possible factors predisposing to haemorrhage in these tumors. Detailed radiological and histopathological evaluation identified two factors which may be associated with higher likelihood of haemorrhage, namely preoperative radiation therapy and vascular abnormalities. Tumor size may not be a major risk factor for haemorrhage. Good outcomes can be achieved with microsurgical management. The histological features presented here differ clearly from findings in previously published case reports.

Los tumores cerebrales son infrecuentes durante el embarazo. Los neurinomas del acústico pueden ser sintomáticos por primera vez durante la gestación y representan el 6-8% de las neoplasias intracraneales. El objetivo de esta comunicación es presentar el caso de una primigesta adolescente que presentó sintomatología neurológica de afectación del VIII par y de fosa posterior, característica de la neurofibromatosis tipo 2. Brain tumors are infrequent during pregnancy. Neurinomas of auditive nerve can get to be symptomatic during gestation, representing 6-8% of the intracranial neoplasias. The objective is to report a case of a pregnant adolescent who present a neurological symptoms of VIII pair affectation and posterior cranial fossa, characteristic of the neurofibromatosis type 2.

Article, 信州医学雑誌 39(6): 751-790(1991)

✓ The brain-stem auditory evoked responses (BAER's) recorded from 56 patients with acoustic neurinomas were analyzed. Ten of the patients had intracanalicular tumors and 46 had extracanalicular tumors. It was possible to obtain BAER's following stimulation of the affected side in 28 patients and after stimulation of the unaffected side in all 56. Five patients (11%) had normal BAER's following stimulation of both sides; three of these patients had intracanalicular tumors. Among BAER's obtained following stimulation of the affected ear, the mean interpeak latency (IPL) for peaks I to III associated with extracanalicular tumors was significantly prolonged relative to controls (p < 0.001), and linear regression analysis revealed a significant positive correlation between tumor size and IPL of peaks I to III (p < 0.05). Analysis of the 56 BAER's recorded after stimulation of the unaffected side revealed a significant positive correlation between the IPL's of peaks III to V and tumor size (p < 0.001). This correlation was not strengthened when accounting for the degree of brain-stem compression. Finally, evidence of preserved function within the auditory pathway, even in the presence of partial hearing loss, is presented. This finding suggests that more patients might benefit from surgical procedures that spare the eighth cranial nerve.

Eighty-five patients with acoustic neurinomas underwent stereotactic radiosurgery with the gamma unit at the University of Pittsburgh (Pittsburgh, PA) during its first 30 months of operation. Neuroimaging studies performed in 40 patients with more than 1 year follow-up showed that tumors were smaller in 22 (55%), unchanged in 17 (43%), and larger in one (2%). The 2-year actuarial rates for preservation of useful hearing and any hearing were 46% and 62%, respectively. Previously undetected neuropathies of the trigeminal (n = 12) and facial nerves (n = 14) occurred 1 week to 1 year after radiosurgery (median, 7 and 6 months, respectively), and improved at median intervals of 13 and 8 months, respectively, after onset. Hearing loss was significantly associated with increasing average tumor diameter (P = 0.04). No deterioration of any cranial nerve function has yet developed in seven patients with average tumor diameters less than 10 mm. Radiosurgery is an important treatment alternative for selected acoustic neurinoma patients.

POLGON (polarized light goniometer) was used to evaluate relative angular changes of shoulders while stepping in patients with unilateral acoustic neurinoma. The mean angular change of shoulders (M. A. C. S.) and its coefficient of variation (C.V.) were selected as parameters of stepping.1. M. A. C. S. was larger on the affected than on the intact side in patients with those with small tumors (1.0 to 1.9 cm).2. In those with advanced tumors, both M. A. C. S. were increased.3. In those with tumors large enough to exert pressure on the midbrain, M. A. C. S. was increased on the affected side.4. The C. V. was influenced by vision.These results suggest that POLGON is useful for determining the stage of acoustic neurinoma from the viewpoint of disequilibrium.

An unusual case of paraganglioma arising from the internal auditory meatus and growing into the cerebello-pontine angle is reported. Clinical features, pre-operative radiological appearances and intra-operative findings were indistinguishable from those of an acoustic neurinoma. However, the paraganglionic nature of the tumour was confirmed by the electron microscopic evidence of neurosecretory features.

Simultaneous development of histologically different primary brain tumors aside from phacomatoses or previous irradiation is rare, and its preoperative diagnosis is still difficult. We report two such cases, a 49-year-old male with an acoustic neurinoma and a cerebellar hemangioblastoma and a 69-year-old female with a parietal convexity meningioma and an ipsilateral frontal lobe astrocytoma. The tumors in the first case developed closely, so some local stimulation probably acted as a developmental factor. However, the tumors in the second case developed in distant areas and were considered coincidental.

It is well known that some patients with acousic neurinoma present with sudden hearing loss as a symptom. However, audiograms specific for acoustic neurinoma have not yet described.In our institutes, 12 out of 34 patients with acoustic neurinoma had sudden hearing loss as their chief complaint. Four of these 12 had audiograms indicating sensory neural hearing loss with “valley type” patterns.We describe these four patients and urge that any patient with sudden hearing loss who has a “valley type” audiogram be evaluated for possible acoustic neurinoma.

Resumen Se describe el caso de una paciente de 13 anos de edad, sin antecedentes de neurofibromatosis, afecta de un neurinoma del VIII par izquierdo e hidrocefalia. El sindrome de hipertension endocraneal fue la clinica que motivo su ingreso hospitalario, no requiriendo ser derivada la hidrocefalia tras la extirpacion precoz del tumor. Se comenta ademas en este articulo: la imagen quistica de la Tomografia Computarizada (TC) cerebral como forma de presentacion radiologica infrecuente; la edad de aparicion de la lesion en la paciente, habiendose descrito solo 15 casos en la infancia; y la dificil preservacion del nervio facial en neurinomas de gran tamano tras la cirugia.

Eine Umfrage unter franzosischen HNO-Arzten sollte ermitteln, ob diese – selbst von einem Vestibularisschwannom betroffen – die gleiche Therapie wahlen wurden, die sie ihren Patienten empfehlen. Die Ergebnisse sind jetzt im Lancet veroffentlicht worden [1].