Improved preservation of function during acoustic neuroma surgery
Hirofumi NakatomiHidemi MiyazakiMinoru TanakaTaichi KinMasanori YoshinoHiroshi ŌyamaMasaaki UsuiHiroshi MoriyamaHiromi KojimaKimitaka KagaNobuhito Saito
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Abstract:
Restoration of cranial nerve functions during acoustic neuroma (AN) surgery is crucial for good outcome. The effects of minimizing the injury period and maximizing the recuperation period were investigated in 89 patients who consecutively underwent retrosigmoid unilateral AN surgery.Cochlear nerve and facial nerve functions were evaluated during AN surgery by use of continuous auditory evoked dorsal cochlear nucleus action potential monitoring and facial nerve root exit zone-elicited compound muscle action potential monitoring, respectively. Factors affecting preservation of function at the same (preoperative) grade were analyzed.A total of 23 patients underwent standard treatment and investigation of the monitoring threshold for preservation of function; another 66 patients underwent extended recuperation treatment and assessment of its effect on recovery of nerve function. Both types of final action potential monitoring response and extended recuperation treatment were associated with preservation of function at the same grade.Preservation of function was significantly better for patients who received extended recuperation treatment.Keywords:
Acoustic neuroma
Cochlear nerve
Neuroma
Nerve Injury
Cross-sectional images of the internal auditory canal (IAC) were investigated in 23 patients with acoustic neuroma in order to clarify the widening of the IAC. The area of the IAC and the ratio of areas (neuroma side:normal side) were calculated. The shape of the IAC was fitted by an ellipse to obtain the length of the axes and the direction of the long axis. The area of the IAC was 34.2+/-12.2 mm2 in the neuroma side and 18.1+/-4.8 mm2 in the normal side. The neuroma side was larger than the normal side in all patients, and the mean ratio of areas was 1.9. However, the degrees of cochlear and vestibular damage did not correlate with the ratio of areas. The mean ratio of axes of the approximated ellipse was 1.17+/-0.09 in the neuroma side and 1.14+/-0.10 in the normal side; however, no significant difference was seen between the ratio of axes. The directions of the long axes were not always consistent with the positions of the originating nerves of the tumour. Referring to hypothetical models of enlargement of the IAC, our data suggest that the widening of the IAC in the acoustic neuroma was expansive. The data also indicated that symptoms of the acoustic neuroma were caused not only by compression of the nerves but also by other mechanisms, such as vascular insufficiency to the inner ear.
Acoustic neuroma
Neuroma
Expansive
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We examined the clinical presentation in patients with a histologically proven ingrowth of the cochlear nerve by acoustic neuroma to see whether this differs from what is known from large acoustic neuroma series. In total, 85 acoustic neuromas had an en bloc dissection to study histologically the relation between the cochlear nerve and the acoustic neuroma. In 21 of these 85 specimens, there was histologic proof of invasion of the cochlear nerve by the tumor. For 13 of these 21 tumors, sufficient clinical data could be retrieved to describe the clinical presentation in these patients. We collected clinical data such as age, sex, presenting symptoms, duration of symptoms, tone audiograms, tumor size measurements and volumetric calculations, and latency interval data I-V of brain stem evoked response audiometry and calculated whether there was any correlation among those data. We also compared these clinical data with the data from some large acoustic neuroma series. No clear difference could be shown between the clinical presentation of acoustic neuroma patients with cochlear nerve ingrowth and the clinical presentations in large acoustic neuroma series. This outcome favors the theory that the hearing impairment in acoustic neuroma patients is mainly the result of compression on the vessels of the cochlea and/or on the cochlear nerve.
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Neuroma
Cochlear nerve
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Audiogram
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Acoustic neuroma
Hypervascularity
Neuroma
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An acoustic neuroma (also known as a vestibular schwannoma) is an intracranial tumour of the vestibular nerve that is commonly treated by surgical resection. Following resection of an acoustic neuroma, patients may experience a range of symptoms that include deficits in gaze stability, mobility and balance. Vestibular rehabilitation may be useful in reducing the severity and minimizing the impact of these symptoms.
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Vestibular rehabilitation
Neuroma
Vestibular nerve
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Acoustic neuroma
Neuroma
Vestibular rehabilitation
Vestibular nerve
Vestibule
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Objective To evaluate the choice of therapeutic methods and MRI diagnosis of acoustic neuroma.Methods The MRIimaging and clinical materials of 60 patients with acoustic neuroma were analyzed,48 cases were underwent an operation,12 cases weretreated conservatively or gamma knife treatment,follow-up ranged from 1 to 4 years.Results There were 62 tumors round the internalauditory canal.There were 58 cases with single acoustic neuroma and two cases with couples acoustic neuroma.28 tumors demonstratedhypointense and 30 tumors demonstrated hypo-and isointense signals on T_1 weighted image.38 tumors demonstrated hyperintense and 24tumors demonstrated hyper-and isointense signals on T_2 weighted image.The Ⅶ,Ⅷ nerves affected side were thickened than that ofopposite side in 32 patients.After Gd-DTPA administration 24 tumors were homogeneously enhanced,26 tumors were inhomogeneously or circularly enhanced in 50 acoustic neuromas of 48 cases.Operation was still the main election for acoustic neuroma.Conclusion MRI is an effective method in the diagnosis of acoustic neuroma,and providing advice for clinics in making therapeutic programs.
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Neuroma
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Abstract In 1989, the Acoustic Neuroma Association established a multisurgeon, multi‐institutional registry to collect data related to the treatment of patients with acoustic neuroma. This report analyzes information from the 1579 surgically treated patients who were entered in the registry between January 1, 1989, and February 28, 1994.
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There have been several reports describing the presence of a dural tail on enhanced MR as being specific for or suggestive of meningioma. It has also been stated that it is a specific diagnostic sign in distinguishing meningioma from acoustic neuroma. We report a case of a dural tail in an acoustic neuroma.
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Neuroma
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