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Over 4 years (1992–1996) we have treated 122 patients with unilateral acoustic neurinoma using the Leksell γ-knife; 121 patients had a follow-up of 2–48 months (median 24 months). Tumor volume was 0.1–17.8 cm3 (median 2.9 cm3); dose to the tumor margin was 10–17.5 Gy (median 12 Gy) delivered on 40–80% isodose (median 50%). A decrease in the tumor volume was observed in 41.3% of patients, the tumor volume was unchanged in 54.6%, and an increase in the tumor despite radio-surgery was observed in 4.1%. Hearing loss was detected in 17.4% of patients, and 3% of patients gained useful hearing after radiosurgery. The overall risk of the method is 4.3% of hearing loss. Weakness of the facial nerve was observed in 1.9% of patients; normalization of the weakness, which was present before radiosurgery, was observed in 6.3% of patients. The overall risk of facial weakness is 1% for γ-knife radiosurgery. Impairment of trigeminal neuropathy was observed in 5% of patients and improvement in 31%. Impairment of vertigo was observed in 5.8% of patients and improvement in 46%. Leksell γ-knife radiosurgery was the primary treatment in 97 patients (80.7%); microsurgical resection preceded radiosurgery in 24 patients (19.8%). Hearing loss and neuropathy of facial and trigeminal nerves before γ-knife radiosurgery were significantly more frequent in the group of patients with previous microsurgical resection than in the group with γ-knife radiosurgery as the primary treatment. After radiosurgery there was no significant difference in impairment or improvement of hearing, facial and trigeminal nerve neuropathy, and vertigo and imbalance for the groups of patients with previous microsurgery or primary γ-knife treatment. After γ-knife radio-surgery neuropathy of facial and trigeminal nerves in the group of patients with previous microsurgery was significantly worse. [ABSTRACT FROM AUTHOR]

Forty-two acoustic neurinomas and seven meningiomas in the cerebellopontine angle were reviewed, and the radiological differential diagnosis of these tumors is discussed. Though enlarged internal auditory meati and characteristic CT findings were reasonably reliable indicators for the diagnosis of acoustic neurinomas, it was angiography which substantiated their correct diagnosis. An arcuate vein was frequently demonstrated with acoustic neurinomas, but never with meningiomas. Visualization of tangled veins seems to favor a diagnosis of acoustic neurinomas. Contrary to earlier reports, tumor stains were most frequently visualized using selective external carotid arteriography. The degree of tumor stains did not aid in differentiating acoustic neurinomas from meningiomas. The importance of using angiotomography, especially in the anteroposterior projection, and external carotid angiography during prolonged injections of large amounts of contrast media, is emphasized. [ABSTRACT FROM AUTHOR]

A consecutive series of 61 patients with pre-operative hearing underwent surgical removal of a large acoustic neurinoma via the lateral suboccipital approach between 1984 and 1996. Brain-stem auditory evoked potentials (BAEP) were present in all cases before surgery and all patients underwent intra-operative monitoring of BAEP. The average tumour size including the portion within the meatus acusticus internus was 30, 5 mm (range 20 mm–49 mm). Complete tumour removal was achieved in all but three cases. In 43.1% of patients with complete tumour removal hearing was preserved initially after surgery. Delayed postoperative hearing loss was observed in 11 patients and hearing recovery in 2 patients leading to 27.5% definite hearing preservation. Hearing preservation was achieved in 37% of cases with tumour size between 20 mm–29 mm and in 23.5% of case with tumour size larger than 30 mm. These results indicate that even in large neurinoms hearing preservation should be attempted in all patients with documented pre-operative hearing and BAEP. [ABSTRACT FROM AUTHOR]

Clinical and computed tomography (CT) findings of twenty-three patients with acoustic neurinoma (AN) and eleven patients with posterior fossa meningioma (PFM) are described. AN frequently (94%) presents with the complaint of hearing loss, while PFM often (60%) presents with non-specific pains in the head or neck. The CT characteristics of AN and PFM in this series were similar to those found in most previous publications. The maximal measured mean diameter of PFM (40.2 mm) was significantly larger than that of AN (26.4 mm). Hydrocephalus was apparently influenced by tumor location rather than by its size. It is concluded that diagnostic ability has been improved in cases of CPA tumors, but not in those of non-CPA PFM, probably because of the earlier clinical presentation of the former. Clinical efforts are still necessary to detect the smaller tumors. [ABSTRACT FROM AUTHOR]

Of 79 acoustic neurinomas seen between June 1980 and June 1984, at least two CT scans were available for each of 23 tumours (21 patients); the scans were performed at intervals of at least 6 months. The volume growth rate of the tumours was either moderate, with a volume doubling time ranging from 205 to 545 days, or slow, with a doubling time ranging from 1090 days to no observable growth. No single clinical, radiological or histological feature correlated with any type of growth rate. however, some conclusions were drawn. If a primary CT scan is negative, at least 1 year should elapse before it is worthwhile taking another scan, even though audiological findings suggest growth; after an an apparently radical removal, at least 3 years should elapse before a check CT scan is worthwhile; and if a small acoustic neurinoma is diagnosed, but for some reason not operated upon, a second CT scan should be carried out 1 year later in order to reassess the case. [ABSTRACT FROM AUTHOR]

Seventy-three cisternographies with metrizamide were performed on 69 patients, mainly for diagnosis of an acoustic neurinoma. Of the 31 patients with pathological findings on cisternography 26 underwent surgery for 23 acoustic neurinomas, one neurinoma of the facial nerve, and two meningiomas. For diagnosing small tumours of the cerebellopontine cistern, cisternography is superior to all other neuroradiological methods. Tomography of the porus acusticus internus and CT scanning are the initial radiological methods in patients with signs of cerebellopontine angle lesions; if no lesion is disclosed by these two methods cisternography with metrizamide should be performed to exclude a small tumour, particularly a small acoustic neurinoma. [ABSTRACT FROM AUTHOR]

We report a case of an acoustic neurinoma that recurred more than 11 years after 'total' tumor removal through the posterior cranial fossa. Recurrent tumor had obliterated the petrous bone, filled the middle ear, and was visible grossly at the external auditory meatus. The unique behavior of this tumor implied that the site of origin was within the labyrinth, beyond the fundus of the internal auditory canal and far lateral to the usual site of acustic neurinoma origin. We offer an hypothesis as to why these tumors occasionally recur, even after clinical 'total' removal. [ABSTRACT FROM AUTHOR]

The vestibular sensory epithelia from two patients with acoustic neurinomas were examined ultrastructurally. Both patients had first undergone posterior fossa operations 8 months and 3 years before residual tumors in the acoustic canals were removed by a secondary translabyrinthine operation. Labyrinthine sensory tissues were also removed for microscopic studies. In case 1, the utricular macula and the lateral and anterior cristae were observed, with all sensory epithelia showing fairly normal findings. Myelinated nerve fibers below the sensory epithelia also appeared normal. In case 2, only the utricular macula could be observed. The sensory epithelium showed severe degeneration, disappearing sensory cells and increasing cytoplasmic filaments of both the sensory cell and the supporting cell. Myelinated nerve fibers below the sensory epithelia were only rarely found. [ABSTRACT FROM AUTHOR]

In view of recent controversies concerning the preservation of hearing in acoustic neurinoma surgery, we examined the courses of the vestibular and cochlear nerve fibers in 12 intact acoustic neurinomas studied in our department. Due to its lack of specificity, the Luxol fast blue stain was found to be inadequate for our study of the nerve fibers. In contrast, Verhoeff's stain proved to be satisfactory when combined with a highly specific immunohistochemical technique. There were macroscopically visible adherences between the tumor and the cochlear nerve in 9 out of the 12 specimens. From those specimens, histological sections were obtained in which both the cochlear nerve and tumor could be clearly identified. In these specimens the cochlear nerve was involved in the tumoral process and there was no clear cleavage plane between the nerve and the tumor. However, all these patients suffered only from minimal losses of hearing as a result of their tumors. [ABSTRACT FROM AUTHOR]

The recovery of facial nerve function after suboccipital removal of 91 acoustic neurinomas is presented. The results after anatomical preservation of the nerve (60 cases), direct anastomosis of the nerve (7 cases), nerve grafting (16 cases), and facial hypoglossal anastomosis (8 cases) are presented after a follow-up period of 31.2 months. A simplified classification was used to describe motor function. The results are compared to those in the literature. [ABSTRACT FROM AUTHOR]

Even with modern neurosurgical techniques preservation of functional hearing in acoustic neurinoma surgery is still impossible in a large number of cases. Due to the necessity of averaging the brainstem auditory evoked potentials (BAEP) this monitoring is not a real time measurement. Therefore the surgeon cannot be sure which manipulation during the tumour dissection has caused the loss of the BAEPs. The direct monitoring of the cochlear nerve (CNAP) may warn the surgeon earlier. But it is not able to explain, which manipulation has caused the worsening of the potentials. A loss of the waves after coagulation of a vessel next to the cochlear nerve may be the result of the heat or of the disturbance of the blood supply. Potentially harmful to cochlear nerve function may be the interruption of inner ear blood supply, thermal or mechanical traumta. Experimental studies are rare to nonexistent. We therefore tested selectively each trauma for its influence on the BAEPs in an animal model. In New Zealand rabbits a lateral craniectomy of the posterior fossa was performed. Care was taken not to retract the cerebellum or to open the inner ear system, because both factors might disturb the BAEPs. Each step of the operation was followed by BAEP recording. After reaching the internal auditory canal, the cerebellopontine angle of 6 animals was exposed to heated water with definitive increasing temperature. The BAEPs did not react significantly until 71 °C was reached and protein coagulation started. In the second group, the internal auditory artery of 6 rabbits was compressed with a microdissector for 3 minutes. Subsequently the BAEPs disappeared in all animals. In the last group a constant pressure of 10 g was applied to 6 cochlear nerves for 1 minute consistently causing the loss of the BAEPs. The results are statistically significant (p=0.03). We therefore concluded that the blood supply of the inner ear is of the upmost importance for cochlear nerve function. Mechanical manipulation should be minimized whereas thermal traumatization of the nerve is only critical when the nerve itself is coagulated. [ABSTRACT FROM AUTHOR]

Cystic acoustic neurinomas (ANs) are less frequent and are different from solid ANs in clinical and radiological features. We had 14 cystic ANs (13.5% of 104 cases) in the last 17 years. Computerized tomographic or magnetic resonance images allowed for the classification of these cystic ANs into three types: Type A being large single cysts with a thin tumourous wall (7 cases); type B single cysts with a thick tumourous wall (3 cases); type C multicystic (4 cases). Half of the cystic ANs were not accompanied by enlargement of the internal auditory canal, despite the largeness of the cysts. The mean size of the tumours was 29 mm in diameter. Type A cysts had a shorter clinical history than types B and C. One patient had intact hearing. In five cases, an atypical initial symptom such as facial pain, dysgeusia, facial palsy, unsteadiness or vertigo presented. The trigeminal nerve was involved in 12 cases, the facial nerve in nine. The characteristic features of cystic ANs are largeness of the tumour, a short clinical history, an atypical initial symptom, facial nerve involvement, and/or no enlargement of the internal auditory canal. In addition, the histological features are a lobular growth pattern, high nuclear atypia, and numerous macro phages. [ABSTRACT FROM AUTHOR]

We examined growth potential of residual intracanalicular tumours left from subtotal removal of large acoustic neurinomas. Eleven patients were followed-up by magnetic resonance (MR) imaging. The interval between surgery and MR study ranged from 12 to 29 years (median, 16 years). MR images of two patients showed no evidence of tumour remnant, and in six a small tumour was localized in the internal auditory canal. The other three showed an intracanalicular tumour protruding slightly towards the intracranial portion. This result suggests that the intracanalicular residual tumours have less risk of regrowth after subtotal removal of acoustic neurinomas. It is advisable to choose intracapsular subtotal removal without opening the internal auditory canal in the treatment of acoustic neurinoma, if it is large in size and there is a high risk of nerve injury. [ABSTRACT FROM AUTHOR]

Trigeminal neuralgia and hemifacial spasm are caused by vascular compression of the cranial nerves at the brainstem in the majority of cases. Trigeminal neuralgia occurring in 3.3% of acoustic neurinomas is usually assumed to be a sign of large tumour size; if associated with small tumour size, an additional pathology, such as typical vascular compression must be suspected and has to be explored at surgery. While facial paresis will usually lead to immediate radiological diagnosis of a possible cerebellopontine angle (CPA) neoplasm, facial spasm is usually not expected to be associated with a CPA tumour. We report on clinical presentation, operative findings, surgical treatment and results in 9 cases of small acoustic neurinomas associated with trigeminal neuralgia and on 4 cases associated with hemifacial spasm. The importance of the clinical characteristics is stressed; if these are typical of a vascular compression syndrome, further exploration at the time of tumour surgery and specific treatment by vascular decompression are necessary. [ABSTRACT FROM AUTHOR]

The hypoglosso-facial nerve anastomosis (HFA) is a valuable surgical procedure for the treatment of certain types of facial paralysis. HFA was performed 1 to 22 months after resection of an acoustic neurinoma in 32 patients where the operation was complicated by unilateral facial palsy. 56% of these patients obtained excellent facial function, and a total of 66% were satisfied and would have repeated the operation even with their present knowledge about the disadvantages. The recovery of facial function after any nerve anastomosis or plastic procedure is never perfect but HFA usually results in symmetry of the face in response and animation of the face during conversation. HFA is most effective when used as soon as possible after facial palsy has developed, provided a sufficient time has passed for any possible spontaneous recovery. This waiting period should not exceed six months. If the operation is done promptly the results improve, probably because only slight atrophy has occurred in the facial muscles. The disadvantages of HFA are hemiatrophy of the tongue, mass movement of the face and, in some instances, hypertonia of the face. The advantages are improved facial tone with ameliorated cosmetic result, protection of the eye, intentional facial movements controlled by the tongue, and movements associated with physiological function of the tongue. [ABSTRACT FROM AUTHOR]

The growth rate of 19 residual acoustic neurinomas was examined in a long-term follow-up study (median, 10 years; range, 5 to 17 years) following intracapsular removal. Of these, 10 (53%) had regrowth, three (16%) showed regression, and six (32%) were unchanged. The 10 acoustic neurinomas showing regrowth were divided into two categories, either solid or cystic, according to computed tomographic findings. Five acoustic neurinomas with cyst formation showed rapid regrowth, with the tumour doubling time ranging from 0.15 to 5.0 years (median, 4.5 years), and required re-operation. Five solid tumours showed slow regrowth, with the tumour doubling time ranging from 9 to 34 years (median, 15 years). Although cyst formation is a major factor in rapid regrowth, residual acoustic neurinomas without cyst formation have a slower growth potential. In this study, 74% of the residual acoustic neurinomas have never required re-operation. It is advisable to choose intracapsular removal if there is major risk of neurological deficits. [ABSTRACT FROM AUTHOR]

A total of 55 cases with unilateral acoustic neurinoma which were operated on by the lateral suboccipital approach was studied to elucidate factors which influence postoperative hearing acuity. We analyzed several factors: preoperative hearing level, tumour size, tumour consistency (cystic or solid), and anatomical location of the cochlear nerve. The size of the tumours ranged from 1.2 to 5.8 cm in diameter. Thirty of 55 cases (55%) preoperatively had remaining cochlear function. The smaller the size of tumour, the higher was the preoperative hearing level excepting those tumours with a diameter of 5 cm or greater, which had relatively good hearing and often contained large cysts. As to the consistency of the tumours, 41 were solid and 14 were cystic, where 19 (46%) and 11 (79%) cases had had preoperative hearing, respectively. Anatomical continuity of the cochlear nerve was maintained at surgery in 15 of 30 cases with preoperatively remaining hearing; cochelar function was preserved after surgery in 9 of the 15 cases. It was located counter-clockwise (caudally) to the facial nerve at an angle of 50 degrees on average when they were projected on the right side. The distance or interrelation between the two nerves had no bearing on postoperative hearing preservation. Postoperatively, hearing acuity was improved in 6 cases (20%) with a mean value of 5.6 dB, unchanged in 3 (10%), and deteriorated in 21 (70%) among the 30 cases with remaining preoperative-hearing. When the tumour was less than 2 cm or cystic, better hearing preservation was expected. Hearing was preserved in 4 cases of the 19 solid tumours (21%) and in 5 of the 11 cystic tumours (45%). No cases with preoperative hearing deficit greater than 60 dB showed postoperative improvement to a useful hearing level. [ABSTRACT FROM AUTHOR]

Of 135 cases operated upon for posterior fossa lesions 103 showed preoperative hearing. In 34 acoustic neurinomas 14 had postoperative initially preserved hearing, in 20 microvascular decompressions 19 had preserved postoperative hearing and in 49 other lesions 5 lost hearing. The relationship between preservation of hearing and the preservation or loss of brainstem auditory evoked potentials (BAEP) waves I and V in the three groups of namely: acoustic neurinomas, microvascular decompressions and other lesions are presented. It is noteworthy that only patients with preserved waves I or V are suitable candidates for intraoperative monitoring. The loss of wave V is usally associated with hearing loss (10 out of 13 cases). But hearing loss is also possible despite preservation of wave I (3 out of 60) or despite preservation of wave V (2 out of 68). The predictive value of the preservation of waves I and V is not an absolute one, but it strongly suggests preserved hearing postoperatively. The dilemma remains that once waves I or V are lost during surgery there is no certainty as to postoperative hearing. If wave V recovers after an initial loss, hearing is usually preserved but not in all cases. In wave I amplitude changes alone were more frequent than in wave V, where latency changes alone were more frequently observed. Particular surgical manoeuvres could be found to be often associated with a wave deterioration. Hearing preservation could never be achieved in patients who already preoperatively had no BAEP. It is concluded that BAEP monitoring is of great value in surgery for microvascular decompression and cerebello-pontine-angle (CPA) tumours with preserved hearing. [ABSTRACT FROM AUTHOR]

In 135 cases of posterior fossa surgery almost exclusively in the cerebellopontine angle (CPA) intraoperative monitoring of brainstem acoustic evoked potentials (BAEP) and partly somatosensory evoked potentials (SEP) was performed. The series consisted of 20 microvascular decompressions, 63 acoustic neurinomas, 7 vascular lesions and 45 other space occupying lesions, mostly in the CPA. BAEP monitoring alone was employed in 76 cases, combined BAEP und SEP monitoring less frequently. The technique of anaesthesia and intraoperative monitoring is presented in detail including an analysis of technical problems (17 in 135=13% of cases) and technical failures (11 of 135=8%). The results of monitoring brainstem pathways contralateral to the lesion are detailed. It is concluded that the technical principles of evoked potential monitoring in posterior fossa surgery are well established. The applications and limits of this technique including its modifications are described. [ABSTRACT FROM AUTHOR]

A careful examination of the shape, location and course of the 8th cranial nerve in medium-sized and large tumours exhibits three distinct variants. In all cases where cochlear function was preserved, the type III variant (12%) in the cranial nerve tumour relationship was observed. The author's experience clearly indicates that, if a tumour is resected in toto, anatomical nerve continuity cannot be preserved in the type I and II variants (48%, respect. 40%). However, in the type I and II variants the patients invariably had preoperative hearing loss. The important criteria which must be considered in order to preserve cochlear function when extirpating acoustic neurinomas are an anatomically intact nerve, the origin of the tumour and its direction of spread, further more the shape, location and course of the 8th nerve components, the quality of preoperative cochlear nerve function, the patttern of vascularization of the statoacoustic nerve and the inner ear, and lastly, but not least a possible infiltration of the vestibular and/or cochlear nerves by the tumour itself. Objective hearing function could be preserved in 62% of small neurinomas (grade II) and 10% of large tumours (grades III and IV). [ABSTRACT FROM AUTHOR]

A large cystic neurinoma of the cerebellopontine angle is reported. This case is unusual in that the clinical history, CT patterns and plain radiological findings were rather misleading for the differential preoperative diagnosis. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Neurology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Neurology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of European Archives of Psychiatry & Neurological Sciences is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: The aim of this article is to explain a surgical approach to solve a complication on a patient treated at our hospital. It is a transmandibular–cervical approach to eliminate a cerebrospinal fluid fistula in the Eustachian tube produced after the removal of an acoustic neurinoma in a patient operated multiple times without success. [Copyright &y& Elsevier]

Acoustic neurinoma affects the acousticofacial nerve and therefore in many cases is a contraindication for cochlear implantation and an indication for brainstem implant. Nevertheless benefit in these patients has been shown after tumour removal and cochlear implantation. The first case of bilateral cochlear implantation in a patient with single-sided untreated acoustic neurinoma is described here. In a 49-year-old woman with progressive hearing loss during the last 12 years we preoperatively diagnosed an acoustic neurinoma of the left side. After cochlear implantation of the right side she was sequentially implanted on the affected side as well. Before surgery radiological control of the tumour for signs of growth was performed and the patient was thoroughly informed of the situation and possible therapies and dangers. Speech discrimination scores obtained in the second implanted ear came up to the performance of the first implant after 6 months. [ABSTRACT FROM AUTHOR]

Copyright of HNO is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We retrieved information on 128 patients with vestibular schwannoma (VS) and 243 patients with Meniere's disease (MD) from the database of the otoneurologic expert system (ONE). The patients filled in a questionnaire concerning their symptoms, earlier diseases, accidents and tobacco and alcohol use. This information was then integrated with results of audiometric, otoneurologic and imaging studies. Forty-nine (38%) of the VS patients had the full triad of vertigo, hearing loss and tinnitus. The vertigo mimicked that in MD in 18 (14%) patients. The mean age of these patients was 48 years. There were 7 men and 11 women. The tumour was small (<2 cm) in eight patients and medium-sized (2-4 cm) in seven patients. The mean attack duration in these 18 patients ranged from 5 min to 4 h. The attacks most commonly (69%) occurred only once or twice a year. Their intensity was moderate. Half of the patients had spontaneous nystagmus. Caloric asymmetry >25% was detected in 61% of the patients. Tinnitus in these patients was mostly (49%) mild. Intense tinnitus was present only in 12% of patients. Headache was present in 25% of these patients. [ABSTRACT FROM AUTHOR]

136 acoustic neurinomas were operated upon by otosurgical transtemporal or translabyrinthine interventions. The otosurgical approach was used when a suboccipital craniectomy with a certain retraction of the cerebellum seemed to be avoidable. The pure otosurgical turmour removal was restricted to a tumour extension up to 2.5 cm starting from the fundus of the internal auditory meatus. The transtemporal route was used when hearing was worth saving and the translabyrinthine when the pure tone audiogram showed an average loss of 50 dB or the speech audiogram a discrimination loss of 50% or more. In larger tumours the neurosurgeon removed the intracranial part of the acoustic neurinome preserving the facial nerve and, if possible, the cochlear nerve as well. If parts of the tumour had remained within the internal auditory meatus or if some uncertainty concerning complete tumour removal persisted, an otosurgical second intervention was considered indicated. In 41 patients the cochlear nerve could be preserved at operation. 12 of these patients showed a preservation of their hearing. [ABSTRACT FROM AUTHOR]