Acoustic Neuromas and the Acoustic Impedance of the Ear

1973 ◽  
Vol 38 (3) ◽  
pp. 345-353 ◽  
Author(s):  
J. H. Macrae
Keyword(s):  
Tympanic Membrane ◽  
Acoustic Neuroma ◽  
Acoustic Impedance ◽  
Theoretical Calculations ◽  
Low Frequencies ◽  
Cochlear Duct ◽  
Acoustic Neuromas ◽  
Affected Side ◽  
Contralateral Ear ◽  
Conductive System

The acoustic impedance at the tympanic membrane was measured at frequencies in the range 100–1000 Hz and found to be abnormal on the affected side in four patients with acoustic neuroma. In all four the resistance was abnormally high at low frequencies on the affected side, and in three the reactance of the affected ear was raised relative to that of the contralateral ear, particularly at low frequencies. The abnormality is attributed to an increase in the input acoustic impedance of the cochlea produced by the increase in protein content of the cochlear fluids and dilatation of the cochlear duct known to occur in acoustic neuroma. This explanation is supported by theoretical calculations carried out on an electric analogue of the conductive system, and it is suggested that similar abnormalities in the acoustic impedance at the tympanic membrane might occur in other pathologies which produce abnormal mechanical conditions in the cochlea.

Anatomical Effects of Sudden Middle Ear Pressure Changes

1979 ◽  
Vol 88 (3) ◽  
pp. 368-376 ◽  
Author(s):  
A. Axelsson ◽  
J. Miller ◽  
M. Silverman
Keyword(s):  
Tympanic Membrane ◽  
Middle Ear ◽  
Round Window ◽  
Applied Pressure ◽  
Positive Pressure ◽  
Air Bubbles ◽  
Scala Tympani ◽  
Middle Ear Pressure ◽  
Contralateral Ear ◽  
Pressure Changes

Acute middle ear (ME) and inner ear changes following brief unilateral phasic ME pressure changes (up to ± 6000/mm H2O) were studied in the guinea pig. Middle ear findings included perforation of the tympanic membrane, serous and serosanguinous exudate and hemorrhage of tympanic membrane and periosteal vessels. Changes were related to magnitude of applied pressure. Perforation and hemorrhage were more commonly seen with negative rather than positive pressure. Air bubbles behind the round window were seen with positive pressures. Occasional distortion, but never perforation of the round window, was noted. Hemorrhage of the scala tympani was observed with both positive and negative pressures; scala vestibuli hemorrhage was found with negative ME pressure. In some instances pressure direction and magnitude related changes were seen in the contralateral ear.

Translabyrinthine Approach for Acoustic Neuroma

Neurosurgery ◽  
2004 ◽  
Vol 54 (2) ◽  
pp. 391-396 ◽  
Author(s):  
John Diaz Day ◽  
Douglas A. Chen ◽  
Moises Arriaga
Keyword(s):  
Surgical Treatment ◽  
Acoustic Neuroma ◽  
Cerebellopontine Angle ◽  
Hearing Preservation ◽  
Retrosigmoid Approach ◽  
The Past ◽  
Translabyrinthine Approach ◽  
Acoustic Neuromas

Abstract THE TRANSLABYRINTHINE APPROACH has been popularized during the past 30 years for the surgical treatment of acoustic neuromas. It serves as an alternative to the retrosigmoid approach in patients when hearing preservation is not a primary consideration. Patients with a tumor of any size may be treated by the translabyrinthine approach. The corridor of access to the cerebellopontine angle is shifted anteriorly in contrast to the retrosigmoid approach, resulting in minimized retraction of the cerebellum. Successful use of the approach relies on a number of technical nuances that are outlined in this article.

Vestibular disorders and impaired path integration along a linear trajectory

2000 ◽  
Vol 10 (1) ◽  
pp. 7-15 ◽  
Author(s):  
Helen S. Cohen
Keyword(s):  
Acoustic Neuroma ◽  
Vestibular Disorders ◽  
Vestibular Input ◽  
Active Motion ◽  
Eyes Closed ◽  
Acoustic Neuromas ◽  
Vestibular Information ◽  
Lateral Distance ◽  
Eyes Open ◽  
Straight Ahead

The goal of this study was to determine if people use vestibular information to keep track of their positions while walking through a simple course. Subjects were normals and patients with chronic peripheral vestibulopathies – each of whom were tested once – and patients with acoustic neuromas tested pre- operatively and one and three weeks post-operatively. Subjects walked over a straight course, 7.62 m, with their eyes open and then with their eyes closed. The time needed for task performance, the forward distance subjects walked before veering, and the lateral distance subjects veered from the straight ahead were recorded. The angle of veering was then calculated. Normals were able to perform this task easily with eyes open or closed. With eyes closed pre-operative acoustic neuroma subjects walked significantly shorter distances before veering than normals but did not veer significantly more than normals or take longer than normals to perform the task. Chronic vestibulopathy subjects, by contrast, were significantly impaired compared to normals on all measures. With eyes open within a week after acoustic neuroma resection subjects could perform the task as well as normals. With eyes closed, however, post-operative subjects were impaired compared to their own pre-operative levels, but they had returned to their pre-operative levels at the second post-operative test. Ataxia was only weakly correlated to any measures and tumor size was not related to performance. These findings support the hypothesis that vestibular input is used for spatial orientation during active motion.

Transmastoid extracranial repair of CSF leaks following acoustic neuroma resection

1989 ◽  
Vol 103 (9) ◽  
pp. 842-844 ◽  
Author(s):  
A. K. Robson ◽  
P. M. Clarke ◽  
M. Dilkes ◽  
A. R. Maw
Keyword(s):  
Cerebrospinal Fluid ◽  
Surgical Management ◽  
Acoustic Neuroma ◽  
Complete Resolution ◽  
Sternomastoid Muscle ◽  
Translabyrinthine Approach ◽  
Suboccipital Craniectomy ◽  
Acoustic Neuromas ◽  
Good Access ◽  
Csf Leaks

AbstractAcoustic neuromas may be resected either by a suboccipital craniectomy or translabyrinthine approach; the latter gives good access without unduly traumatising the brainstem, but can lead to a higher incidence of cerebrospinal fluid (CSF) leaks. The surgical management of these leaks can be difficult; we describe a transmastoid extracranial technique using pedicled sternomastoid muscle that has produced complete resolution of the leak in all cases managed in this way.

Some Observations in a Case of Acoustic Neuroma

1978 ◽  
Vol 43 (4) ◽  
pp. 459-466 ◽  
Author(s):  
Shlomo Silman ◽  
Stanley A. Gelfand ◽  
Tong Chun
Keyword(s):  
Hearing Loss ◽  
Sensorineural Hearing Loss ◽  
Acoustic Neuroma ◽  
Recent Theory ◽  
Acoustic Neuromas ◽  
Apparent Relationship ◽  
Stapedius Reflex ◽  
The Subject ◽  
Acoustic Tumor ◽  
Insight Into

The subject was a 47-year-old male with a moderate asymmetrical sensorineural hearing loss that initially presented cochlear signs except for positive stapedius reflex results. Over the course of only five weeks, he developed the audiological constellation of retrocochlear involvement. The retrocochlear results were confirmed by the removal of an acoustic tumor. The results highlight the importance of audiological monitoring and reflex measures in the identification of acoustic neuromas. Several observations provide insight into the apparent relationship between loudness and the stapedius reflex. The findings are discussed with reference to a proposed extension of Borg’s recent theory that elevated reflex thresholds and reflex decay reflect differing degrees of the eighth nerve destruction.

scholarly journals Sigmoid Sinus Patency following Vestibular Schwannoma Resection via Retrosigmoid versus Translabyrinthine Approach

2020 ◽  
Author(s):  
Andrea Ziegler ◽  
Nadeem El-Kouri ◽  
Zaneta Dymon ◽  
David Serrano ◽  
Mariah Bashir ◽  
...  
Keyword(s):  
Acoustic Neuroma ◽  
Treatment Options ◽  
Middle Cranial Fossa ◽  
Sigmoid Sinus ◽  
Surgical Approaches ◽  
Stereotactic Radiation ◽  
Acoustic Neuromas ◽  
Significant Difference ◽  
Sinus Stenosis ◽  
Dural Venous Sinus

Abstract Introduction The treatment options for acoustic neuromas are observation with serial imaging, stereotactic radiation, or surgical resection. The most common surgical approaches are the translabyrinthine (TL), the retrosigmoid (RS), and the middle cranial fossa. During the TL approach the sigmoid sinus is decompressed with bipolar cautery to allow greater medial exposure. It is unknown if this causes any long-term narrowing or thrombus of the sigmoid sinus. Methods We performed a retrospective review of patients who underwent acoustic neuroma resection to determine if patients undergoing a TL approach for acoustic neuroma resection develop radiographic evidence of sigmoid sinus stenosis or thrombosis compared with patients undergoing a RS approach. Results A total of 128 patients were included in this study, 56 patients underwent a TL approach and 72 patients underwent a RS approach. We compared the preoperative and postoperative diameter of the ipsilateral and contralateral sigmoid sinus at proximal, midpoint, and distal locations on magnetic resonance imaging examinations. There was no significant difference between the preoperative and postoperative diameter of the ipsilateral or contralateral sigmoid sinus based on surgical approach. Conclusion Decompression of the sigmoid sinus during the TL approach does not have a significant postoperative effect on the dural venous sinus patency.

Criteria for Selecting an Optimal Device for the Contralateral Ear of Children with a Unilateral Cochlear Implant

2015 ◽  
Vol 20 (5) ◽  
pp. 314-321 ◽  
Author(s):  
Sung-Wook Jeong ◽  
Min-Young Kang ◽  
Lee-Suk Kim
Keyword(s):  
Speech Perception ◽  
Cochlear Implant ◽  
Hearing Threshold ◽  
Low Frequency ◽  
Hearing Level ◽  
Monosyllabic Word ◽  
Low Frequencies ◽  
Speech Perception In Noise ◽  
Clinical Criteria ◽  
Contralateral Ear

Objective: To identify clinical criteria for selecting the aiding device for the contralateral ear of children with a unilateral cochlear implant (CI). Methods: Sixty-five children, including 36 bilateral CI users and 29 bimodal users, participated in the study. A speech perception test (monosyllabic word test) in noise was administered. The target speech (65 dB sound pressure level) was presented from the front loudspeaker, and noise (10 dB signal-to-noise ratio) was presented from 3 directions: from in front of the child and 90° to the child's right and left sides. The test was performed using the first CI alone and under bilateral CI or bimodal conditions. The bilateral benefits to speech perception in noise were compared between bilateral CI users and bimodal users. Results: Significant benefits in speech perception in noise were evident in bilateral CI users in all 3 noise conditions. In bimodal users, the hearing threshold at low frequencies of ≤1 kHz in the nonimplanted ear affected the bilateral benefit. Bimodal users with a low-frequency hearing threshold ≤90 dB hearing level (HL) showed a significant bilateral benefit in various noise conditions. By contrast, bimodal users with a low-frequency hearing threshold >90 dB HL showed no significant bilateral benefits in all 3 noise conditions. Conclusions: Bilateral CI and bimodal listening provide better speech perception in noise than unilateral CI alone in children. The contralateral CI is better than bimodal listening for children with a low-frequency hearing threshold >90 dB HL. A hearing threshold at low frequencies of ≤1 kHz may be a good criterion for deciding on the type of device for the contralateral ear of children with a unilateral CI.

Asymmetry of the Internal Auditory Canals without Acoustic Neuroma

1978 ◽  
Vol 87 (6) ◽  
pp. 815-820 ◽  
Author(s):  
Kenneth D. Dolan ◽  
Richard W. Babin ◽  
Charles G. Jacoby
Keyword(s):  
Posterior Fossa ◽  
Acoustic Neuroma ◽  
Cerebellopontine Angle ◽  
Clinical Presentation ◽  
Internal Auditory Canal ◽  
Internal Auditory Meatus ◽  
Radiographic Appearance ◽  
The Past ◽  
Acoustic Neuromas ◽  
Normal Architecture

During the past five years, nine patients with “significant” unilateral enlargement of one internal auditory canal by polytomography were subsequently found to have freely filling canals on contrast posterior fossa myelography. The radiographic appearance of the enlarged canals varied greatly and included all the various configurations usually suggestive of acoustic neuroma. Likewise, the clinical presentation varied greatly from asymptomatic to highly suggestive of cerebellopontine angle tumor. This series underscores the essential nature of posterior fossa studies in the evaluation of potential acoustic neuromas and the variability of the normal architecture of the internal auditory meatus.

Effect of tympanic membrane perforation on middle-ear sound transmission

2009 ◽  
Vol 123 (S31) ◽  
pp. 81-89 ◽  
Author(s):  
Y Matsuda ◽  
T Kurita ◽  
Y Ueda ◽  
S Ito ◽  
T Nakashima
Keyword(s):  
Image Analysis ◽  
Tympanic Membrane ◽  
Chronic Otitis Media ◽  
Tympanic Membrane Perforation ◽  
Conduction Disturbance ◽  
Low Frequencies ◽  
Tympanic Membrane Perforations ◽  
Precise Evaluation ◽  
Membrane Perforation ◽  
Sound Conduction

AbstractTympanic membrane perforation causes a sound conduction disturbance, and the size of this conduction disturbance is proportional to the perforation area. However, precise evaluation of perforation size is difficult, and there are few detailed reports addressing this issue. Furthermore, such evaluation becomes more difficult for irregularly shaped perforations. This study conducted a quantitative evaluation of tympanic membrane perforations, using image analysis equipment.A significant correlation was found between the degree of sound conduction disturbance and the perforation area; this correlation was greater at low frequencies following a traumatic perforation. The conductive disturbance associated with chronic otitis media was significantly greater at low frequencies. Circular perforations caused only minor conduction disturbance. Perforations in the anteroinferior quadrant were associated with greater conduction disturbance. Traumatic spindle-shaped perforations and malleolar perforations were associated with greater conduction disturbance.

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