Hearing performance of cochlear implant patients in noise.
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Adult↗
Biomedical subjects
W Gstoettner
Publications and source records attributed to W Gstoettner.
Long-term results of different treatment modalities in 37 patients with glomus jugulare tumors.
The results of different forms of treatment of 37 patients with previously untreated glomus jugulare tumors were compared retrospectively. According to the Fisch classification system, 6 patients presented with class B tumors, 19 class C and 12 patients with class D. Twenty-eight patients underwent surgery and 9 patients had primary radiation therapy (to 50 Gy). In 20 of the surgical cases (71%), radical tumor removal could be achieved and required no further treatment over a follow-up period of 8.6 years (range 2-15 years). Incomplete tumor resection with postoperative radiation therapy resulted in progressive tumor growth in three cases. One patient in this group experienced subarachnoid bleeding that had to be managed by salvage surgery. After primary radiation therapy, glomus jugulare tumors were still evident on magnetic resonance imaging scans, but showed no signs of disease progression. As a result of our experience, we found that a one-stage radical tumor resection performed in collaboration by otologic surgeons and neurosurgeons was the best treatment for patients with large glomus jugulare tumors.
Adolescent↗
Reversible sensorineural hearing impairment induced by a carotid body tumor.
A case of a 62-year-old Austrian man having a 25-year history of a right-sided carotid body tumor (CBT) is presented. Three months before being transferred to the University of Vienna for tumor resection the patient developed symptoms of tinnitus, progressive ipsilateral hearing loss and dysphagia. Pure-tone audiometry demonstrated a 50 dB right sensorineural hearing loss. A 6 x 6 x 4 cm firm, pulsatile mass was found in the right carotid triangle and extending towards the base of the skull. One week after radical tumor resection all preoperative symptoms disappeared and hearing of the right ear recovered. Review of the available literature showed that hearing loss and tinnitus are unusual symptoms of a CBT. Our findings suggest that routine audiometric evaluations in such cases of CBT patients should be obtained in order to determine the real incidence of audiological disorders.
Audiometry, Pure-Tone↗
Intracochlear position of cochlear implant electrodes.
There are many different types of cochlear implants available on the market today and they are constantly being re-evaluated and changed. Knowledge of the exact position of the electrode within the cochlea is important in order to improve the electrical stimulation of the hearing nerve by the implants. The stimulating electrodes are usually located peripherally within the scala tympani, although several attempts have been made to develop peri-modiolar located electrode arrays. In this study, our goal was to evaluate the intracochlear positions of Nucleus, Combi 40/Combi 40 +, and newly developed peri-modiolar positioned electrodes by inserting them into fresh human temporal bones. After insertion, the bones were then histologically processed with the electrodes in situ, following perilymphatic formalin perfusion and methylmethacrylate embedding. Sections of the bones 80-100 microm thick were prepared using a sawing, grinding and polishing technique. This technique resulted in excellent preservation of the inner ear structures and clear identification of each electrode. The different types of electrodes were then evaluated as to their insertion depth, trauma to cochlear structures and location in relation to the scala tympani walls.
Cadaver↗
Cochlear implantation as a successful rehabilitation for radiation-induced deafness.
Radiotherapy of the head and neck can be associated with conductive and/or sensori-neural hearing loss. We report the case of a 67-year-old man who developed complete bilateral deafness caused by labyrinthitis and radiation-induced neuritis of the acoustic nerve after postoperative radiotherapy of a nasopharyngeal carcinoma. Two years postoperatively extensive clinical workup including computed tomography and magnetic resonance imaging showed no recurrence or secondary brain tumors. To facilitate sound perception a Combi 40 cochlear implant was implanted. Because of fibrosis the insertion depth of the stimulating electrode into the scala tympani was limited and therefore a "short electrode version" was used. Six months after implantation the patient had achieved an excellent environmental sound recognition and moderate speech intelligibility. Present experiences has shown that although radiotherapy can cause damage to the labyrinth and acoustic nerves and central hearing pathways, there may still be surviving auditory nerve fibers that can be stimulated successfully by a cochlear implant.
Aged↗
Variant petrotympanic fissure as possible cause of an otologic complication during TMJ arthroscopy. A case report.
In this reported case, a variant petrotympanic fissure--opening at the height of the orifice of the Eustachian tube into the hypotympanon--was identified by high resolution computed tomography (CT) as the possible cause of a tympanic membrane perforation. Inner ear function was preserved by an otosclerotic stapes which prevented destruction of the labyrinth. The perforation was closed by a myringoplasty and was to be followed by a stapedectomy after six months to restore normal hearing. Surgeons performing temporomandibular joint arthroscopy should be aware that in a small percentage of patients a variant anatomy of the tympanic plate exists and, therefore, great care must be exercised in the manipulation of instruments near this structure. A preoperative high resolution CT with thin slices of the temporal bone might allow identification of these high risk patients.
Adult↗
MR imaging of the inner ear and cerebellopontine angle: comparison of three-dimensional and two-dimensional sequences.
OBJECTIVE: The aim of the study was to compare the ability of three-dimensional (3D) T2-weighted turbo spin-echo and gadolinium-enhanced 3D T1-weighted gradient-echo sequences with two-dimensional (2D) T2-weighted turbo spin-echo and gadolinium-enhanced T1-weighted spin-echo sequences to reveal anatomic and pathologic structures of the inner ear and cerebellopontine angle. SUBJECTS AND METHODS: Thirty-one patients underwent axial 2D T2-weighted turbo spin-echo and 3D T2-weighted turbo spin-echo MR imaging, axial and coronal 2D T1-weighted spin-echo MR imaging before and after i.v. injection of gadopentetate dimeglumine, and gadolinium-enhanced axial 3D T1-weighted gradient-echo MR imaging. The visualization of anatomic and pathologic structures on the different sequences was evaluated. Statistical analysis was performed from the data obtained from the visual evaluation of the anatomic structures on the different sequences. Signal-to-noise and contrast-to-noise ratios were calculated for the gadolinium-enhanced 3D T1-weighted gradient-echo and 2D T1-weighted spin-echo sequences, and statistical evaluation was performed. RESULTS: The 3D sequences enabled excellent visualization of 94% of all evaluated anatomic structures, and the 2D sequences enabled excellent visualization in only 3% of these structures. Pathologic structures were revealed in all cases by one or both of the 3D sequences. Diagnosis in all patients could be made by using the combination of the 3D T2-weighted turbo spin-echo and the gadolinium-enhanced 3D T1-weighted gradient-echo sequences. However, the 2D sequences failed to show pathologic structures in three patients. We found a significant statistical difference for the visualization of anatomic structures with the 3D and 2D sequences (p < .0001) and no significant statistical difference for the signal-to-noise and contrast-to-noise ratios with the 3D T1-weighted gradient-echo and 2D T1-weighted spin-echo sequences. CONCLUSION: The 3D sequences revealed anatomic structures significantly better than did the 2D sequences and showed pathologic structures considerably more often than did the 2D sequences in all patients. MR imaging of the inner ear and cerebellopontine angle performed with 3D T2-weighted turbo spin-echo and gadolinium-enhanced 3D T1-weighted gradient-echo sequences provided the most accurate imaging leading to diagnosis in cases of abnormality.
Adult↗
[Rehabilitation of patients with hearing loss by cochlear implants].
In the last decade, the rehabilitation of postlingually deaf adults and prelingually deaf children with cochlear implants has been established as a treatment of deafness. The technological development of the implant devices and improvement of the surgical technique have led to a considerable increase of hearing performance during the last years. The postlingually deaf adults are able to use the telephone and may be integrated in their original job. Prelingually deaf children can even visit normal schools after cochlear implantation and hearing rehabilitation training. In order to preoperatively establish the state of the cochlea, radiological diagnosis of the temporal bone is necessary. High resolution computerized tomography imaging of the temporal bone with coronar and axial 1 mm slices and MRI with thin slice technique (three dimensional, T2 weighted turbo-spinecho sequence with 0.7 mm slices) have proved to be valuable according to our experience. Furthermore a postoperative synoptical X-ray, in a modified Chausse III projection, offers good information about the position of the implant and insertion of the stimulating electrode into the cochlea.
Adult↗
Surgical experience with the Combi 40 cochlear implant.
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Adult↗
Speech understanding in quiet and in noise with the CIS speech-coding strategy (MED EL Combi-40) compared to the MPEAK and SPEAK strategies (Nucleus).
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Age of Onset↗
Postoperative radiographic assessment of the Combi 40 cochlear implant.
OBJECTIVE: The aims of this study were to establish a plain radiographic technique for the assessment of the postoperative appearance, position, and insertion depth of the Combi 40 cochlear implant and to correlate the radiologic findings with surgical reports. SUBJECTS AND METHODS: In an experimental study, an electrode of the Combi 40 device was inserted into the cochlea of a cadaveric skull. Digital radiographs were obtained in a modified Chausse III projection, in which the skull was placed supine on the radiography table with the infraorbitomeatal line strictly perpendicular to the film cassette. The skull was then rotated 30 degrees away from the side to be examined, and the central X-ray beam was angled 15 degrees cephalad to the infraorbitomeatal line. On these radiographs, the point of cochleostomy was marked by a needle tip and was projected inferior to the vestibule and on a line drawn through the superior semicircular canal and the vestibule. The appearance and position of the electrode was evaluated. An electrode was defined as completely inserted if all electrode contacts projected medial to the line drawn through the superior semicircular canal and the vestibule. We also studied cochlear implant insertion of the Combi 40 device in 37 patients. Postoperative digital radiographs of these patients were obtained and analyzed for the criteria as defined in the cadaveric study. In addition, the insertion depth of the electrode and the angle of insertion were measured on the radiographs. This depth was correlated with depth of insertion as estimated at surgery. RESULTS: The cadaveric study showed that the completely inserted electrode was seen on radiographs as a nonoverlapping spiral within the cochlea. All electrode contacts projected medial to the line drawn through the superior semicircular canal and the vestibule. In all 37 patients, the electrode could be seen without overlapping. According to our criteria, a completely inserted electrode was seen in 32 patients. In these patients, the insertion depth ranged from 21 to 34 mm and the angle of insertion ranged from 350 degrees to 810 degrees. In two patients, we saw a completely inserted electrode with a bend. In three patients, an incompletely inserted electrode was seen. Excellent correlation existed between the radiologic and surgical results with regard to insertion depth (r = .92). CONCLUSION: Digital radiographs obtained in the modified Chausse III projection allow clear depiction of the electrode and avoid overlapping. Such radiographs enable a reliable and accurate assessment of the position and insertion depth of the electrode of this new cochlear implant. Such images can serve as a baseline for further radiographic examinations when extrusion or slippage of the electrode is clinically suspected.
Adult↗
Cochlear implant deep electrode insertion: extent of insertional trauma.
We have recently undertaken deep insertions of the Combi-40 cochlear implant electrode (Med-E1 Corp., Innsbruck, Austria) into apical regions of the scala tympani using a cochleostomy approach. In order to examine the extent of the insertional trauma, 12 fresh human temporal bones were implanted with original Combi-40 electrodes. The specimens were histologically processed with the implants in place by employing a sawing and grinding technique. In most cases, only very discrete distortions of the epithelium of the spiral ligament occurred within the middle cochlear turns. Furthermore, a slight displacement of the basilar membrane caused by the electrode was occasionally seen. However, in 2 cases more severe damage such as basilar membrane rupture and electrode displacement was found. Attempts to insert the electrode beyond the point of first resistance resulted in electrode kinking within the basal cochlear turn with subsequent fracture of the osseous spiral lamina. According to our results, deep electrode insertions do not aggravate the insertional trauma provided no force is applied when resistance is felt.
Cochlea↗
Auditory fractal random signals: experimental data and clinical application.
In the mammalian primary cochlear afferents, fractals in the postsynaptic bursting behaviour triggered by a constant perisynaptic release of glutamatergic transmitter agonists have been demonstrated. In order to test the validity of fractally coded auditory signal transmission in man, frequency, intensity and temporal resolution tests were performed in cochlear implanted patients. All patients clearly recognized the fractally coded signals transmitted to the cochlear implants. These first results demonstrate evidence for fractally coded auditory signal transmission in man.
Adult↗
Preclinical detection of initial vestibulocochlear abnormalities in a patient with multiple sclerosis.
A 49-year-old woman presented with a third-degree continuous spontaneous nystagmus to the left which was followed by a sudden, almost complete deafness of her left ear. These symptoms were established as the sole initial presenting manifestations of multiple sclerosis (MS). Magnetic resonance imaging demonstrated a lesion within the left eight nerve root-entry zone and multiple small central lesions beneath the lateral ventricles. Pure-tone audiometry returned to normalcy after 2 weeks and speech discrimination was 100% after 10 weeks. Auditory brainstem responses (ABRs) showed abnormal parameters during a 10-month follow-up period after the acute hearing loss. Furthermore, desynchronization in ABR testing could be demonstrated 2 days before onset of hearing loss, which was interpreted as a prodromal ABR sign of the incipient MS attack.
Adult↗
Specificity of auditory brainstem response audiometry criteria in acoustic neuroma screening as a function of deviations of reference values in patients with cochlear hearing loss.
On the basis of 79 patients with cochlear hearing loss, the statistical distribution of two criteria commonly used in auditory brainstem response audiometry (ABR) was analyzed: the interaural V latency difference (ILD V) and the interaural difference of I-V interpeak interval (ID I-V). The distribution of both criteria was Gaussian. By evaluating their standard deviations the percentages of statistical false-positives were estimated. The estimated results were 24% false-positive findings using the decision criterion ILD V greater than 0.2 ms and 5.4% false-positive findings using ID I-V greater than 0.3 ms. This corresponds closely to the actual false-positive ABR rates obtained in this sample: 21.5% and 6.3%, respectively. In a separate series of 301 unselected cases with asymmetric sensorineural hearing loss, 29 ABRs were suspect for retrocochlear pathology. In 20 patients, ABRs were absent due to severe hearing loss. Retrocochlear pathology could be confirmed in only 2 cases (both from the group with ABR present). Thus, 47 ABRs (15.7% of 299) were false-positive.
Cochlear Diseases↗
Central projections from singular parts of the vestibular labyrinth in the guinea pig.
Primary afferent projections from singular parts of the vestibular labyrinth were studied in the guinea pig. The posterior ampullary nerve, the common trunk of the anterior and lateral ampullary nerves, as well as fibers innervating the macula sacculi or the macula utriculi were traced with crystals of horseradish peroxidase (HRP) lyophilisate. Posterior, as well as anterior and lateral ampullary fibers were found to project extensively to the superior vestibular nucleus, but also reached the other main vestibular nuclei. Saccular fibers projected mainly to the lateral parts of the lateral vestibular nucleus and to the adjoining descending and superior vestibular nuclei as well as to group y. Modest projections could be followed to the medial vestibular nucleus. Furthermore, a distinct saccular projection to the cochlear nuclei was evident. Utricular projections reached the four main vestibular nuclei with a denser accumulation of fibers within ventral parts of the lateral, descending and superior vestibular nuclei.
Animals↗
The origin of the vestibulo-cochlear projection in the guinea pig.
Previous tracer studies have revealed the sacculus to be connected to the vestibular and cochlear nuclei in the guinea pig. Due to its own innervation pattern, an anterior and posterior part of the sacculus can be distinguished. The present study investigated whether the two parts differ concerning their fiber contribution to the vestibulo-cochlear projection. After tracing the nerve of the posterior sacculus with horseradish peroxidase (HRP), the vestibulo-cochlear fibers were clearly recognizeable and showed distinct terminal labeling within the cochlear nuclei. In contrast, no terminals were identified in the cochlear nuclei after tracing the anterior sacculus. These results may further substantiate the guinea pig vestibulo-cochlear projection as a central pathway for saccular acoustic sensation.
Afferent Pathways↗