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At least 1,117 records · Page 62Linked to original sources
PubMed1991

Recurrence after incompletely resected acousticus neurinomas.

It is known that the recurrence rate is high when an acoustic neurinoma is incompletely excised, but the details of the process of recurrence are still unclear. We reviewed the recurrence of acoustic neurinomas, as evaluated by computed tomography (CT) or magnetic resonance imaging (MRI), in 51 consecutive patients over the past 10 years who underwent tumor resection and had postoperative follow-up by CT or MRI. The factors promoting recurrence related to incomplete excision of tumor were analyzed. Total resection of the tumor was performed in 22 patients (43%), nearly total resection in 17 patients (33%) and subtotal resection in 12 patients (24%). The recurrence rates were 29% (5 of 17 patients) and 25% (2 of 8 patients) for nearly total and subtotal resection, respectively, whereas no recurrence occurred following total resection. Of the patients having nearly total resection, all recurrences arose from residual tumor in the internal auditory meatus (5 of 12 patients). In contrast, there were no recurrences from residual tumor at the site of the brain stem (none of 4 patients). Acoustic neurinomas should be totally removed through neurosurgical and neuro-otological approaches whenever possible. If a small fragment of tumor is left in the internal auditory meatus due to fear of damaging the facial or cochlear nerves, it should be strictly followed up by CT or MRI.

Adolescent↗
PubMed1992

Postoperative hearing recovery in a case of delayed hearing loss after acoustic neurinoma removal.

Delayed postoperative hearing loss after acoustic neurinoma removal is seldom observed. The presented case illustrates the phenomenon of delayed postoperative hearing loss which was observed 4 days after removal of a large acoustic neurinoma. Intraoperative brainstem auditory evoked potentials (BAEP) revealed a gradual loss of wave V with preservation of wave I. In animal experiments a dissociated loss of BAEP has been associated with impairment of microcirculation due to secondary edema. Vasoactive treatment was initiated and after 11 days a partial hearing recovery could be documented. Transient disturbance in microcirculation of vasa nervorum of the cochlear nerve is assumed to be responsible for postoperative hearing fluctuation.

Audiometry, Pure-Tone↗
PubMed2006

[A case of infarction in brainstem and cerebellum as a initial symptom with bilateral hearing loss].

A 56-year old male presented with a sudden onset of bilateral hearing difficulty. He complained of dizziness and gait disturbance at the onset and subsequently developed bilateral hearing loss and tinnitus. Brain MRI revealed multiple infarcts in bilateral middle cerebellar peduncles, bilateral cerebellar hemispheres and the right cerebral peduncle. Three dimentional computed tomography angiography (3D-CTA) showed severe stenosis of bilateral vertebral arteries. Infarcts were located in the border zone between anterior inferior cerebellar artery (AICA) and superior cerebellar artery (SCA), suggesting hemodynamic infarctions. Auditory brain stem responses (ABR) were recorded three times. The initial ABR demonstrated all waves except for wave I on day 14. Wave I on the left was normal, while wave I peak latency on the right was prolonged. On day 61, all waves were recorded, although peak latencies of waves III to V and interpeak intervals of the wave I to III on the right side were prolonged. Involvements of the cochlear nerve and pontine auditory pathway were suggested from the ABR abnormalities in this case.

Anterior Cerebral Artery↗
PubMed1990

[Localization of leu enkephalin in animal and human brain stem].

At investigating brains of humans, rabbits and pigeons by means of the cytochemical method, using peroxidase-++--antiperoxidase complex, an immune positive reactivity to ++leu enkephalin has been revealed in neurons of the substantia nigra, in the grey substance of the aqueduct area, in the posterior nucleus of the cochlear nerve, in the ventral part of the giant-cellular reticular nucleus in the nucleus of the solitary tract and in capillaries of the brain also. By means of some ultrastructural investigations certain places have been determined where synapsis and deposition of neuropeptides take place. These are specialized endotheliocytes, pericytes and neurons, situating especially close to the capillary wall.

Animals↗
PubMed1989

Monitoring of intraoperative auditory brainstem responses.

Intraoperative ABR monitoring provides a measure of reassurance when a surgical procedure places the cochlear nerve or its blood supply in jeopardy. ABR monitoring has demonstrated its place in the operating room during retrolabyrinthine vestibular nerve section for vertigo, and in acoustic neuroma operations, when hearing preservation is a high priority in surgical outcome.

Brain Stem↗
PubMed1989

Preservation of hearing in the surgical removal of cerebellopontine angle tumors.

It is claimed that postsurgical hearing preservation is possible in about 5 to 8 per cent of cases of acoustic neuroma. Even with small tumors, hearing preservation can be accomplished in about half of the patients who are fortunate to have anatomic integrity of facial and cochlear nerves, as well as intact inner ear blood supply at the end of the surgical procedure. Monitoring of seventh and eighth nerve function through evoked potentials may be important. On the other hand, even if evoked potentials are preserved during surgery with wave V latency and amplitude similar to preoperative recording, hearing may still be completely lost during the immediate postoperative period. There is no predictable pattern that assures postoperative preservation of hearing. In Case 2, the seventh and eighth nerves as well as the inner ear blood supply were carefully dissected and anatomically and electrophysiologically preserved during the intraoperative period. At the end of the surgical procedure, the evoked potentials were the same as preoperatively. Nevertheless, the patient ended up with no detectable hearing postoperatively. We feel that the suboccipital-retrosigmoid transcanal approach can be safely used for the removal of cerebellopontine angle tumors of all sizes. We believe the argument that "only the translabyrinthine approach can accomplish total tumor removal" is not valid. No complications have been attributed by having the patient in the semisitting position. Older patients, who cannot tolerate the semisitting position, are operated on while in the park bench position. Planned subtotal removal of a CPA tumor is done with the patient in the supine position (transmastoid-retrolabyrinthine or retrosigmoid). The relationship between the otologic surgeon and neurosurgeon is very important. The surgical approach used should be selected on the basis of the combined experience of the surgical team. Finally, an attempt should be made to preserve facial nerve function and hearing in all suitable patients. The postoperative course using the suboccipital-retrosigmoid approach is usually benign, and the patients are discharged from the hospital between 7 and 10 days following surgery. The translabyrinthine approach, in our opinion, should be reserved for smaller lesions in patients with anacusis or with residual hearing that is not worth saving.

Adult↗
PubMed1989

[Life-threatening complications and severe neurologic sequelae in surgery of acoustic neurinoma].

Surgical treatment of acoustic neurinoma carries a high risk of mortality. Recent history of successful management sparing the facial, mixed, and even cochlear nerves, as well as of a substantially lower incidence of postoperative complications or neurological sequelae, should not give grounds for any false sense of security to undermine one's alertness during the pre, peri- and postoperative phases of the intervention. The overall mortality rate for surgical neurinoma cases was 0.7%. Severe, disabling CNS-related neurological sequelae, chiefly affecting the cerebellum, occurred in 0.4% of cases.

Adolescent↗
PubMed1987

Diagnostic value of extratympanic electrocochleography in Menière's disease.

In order to examine the usefulness of the noninvasive extratympanic electrocochleography (ECochG) in the diagnosis of Menière's disease, the results of extratympanic ECochG, performed on 28 normally hearing ears, 3 ears with otosclerosis and 325 ears with sensorineural hearing loss of various origins including 56 Menière ears, were analyzed. The characteristics of summating potential (SP) parameters in Menière ears were different from those of ears with hair cell loss due to streptomycin and kanamycin ototoxicity and noise, while there was no difference between the action potential (AP) of the cochlear nerve parameters of Menière ears and ears with hair cell loss. A much higher incidence of increased-SP/AP amplitude ratios in Menière's disease was observed than in hearing loss of other origins. The results demonstrate the usefulness of noninvasive extratympanic ECochG in the diagnosis of Menière's disease.

Action Potentials↗
PubMed1986

Evidence for hair cell degeneration as the primary lesion in hearing loss of the elderly.

All patients in a geriatric unit showed a hearing loss with a mean value of approximately 60 dB HL. Auditory brain stem evoked responses had normal amplitudes but, in most cases, waves I and II were absent. Extratympanic electrocochleograms produced well-marked action potentials with evidence of a type of recruitment. These results suggest a primary disturbance of cochlear function peripheral to the cochlear nerve. Examination of stained surface preparations of the organ of Corti showed complete atrophy of all hair cells at the end of the basal coil and severe outer hair cell loss in all three coils. This was accompanied by a severe alteration - giant stereociliary degeneration - in some surviving cells in all cases, but no other consistent alterations in the cochlea. These findings point towards degenerative change in the hair cells as the basis for hearing loss in the elderly.

Aged↗
PubMed1985

[Removal of acoustic neuromas of the cerebellopontile angle with transtemporal approach by the middle cranial fossa].

The enlarged transtemporal middle fossa approach to the cerebello-pontine angle is adequate for complete removal of acoustic neuromas up to 4.0 cm in diameter (sizes B and C according to Fisch). A description of the surgical technique and the results of 63 operations are presented (13, 23 and 27 tumours of sizes A, B and C respectively). 51 tumours were completely removed, 6 had a voluntary palliative incomplete resection for medical reasons or on the only remaining hearing ear. Only 6 patients (one in the last 40 consecutive cases) had an incomplete resection due to the limited exposure of the tumour. In 44 ears the cochlear nerve could be preserved, 28 of which showed postoperative hearing function (8 size A, 10 size B, 10 size C). There was no operative mortality, no severe hemorrhage nor any permanent neurological complication. The facial nerve function was well preserved in 48 of 56 patients followed up.

Adolescent↗
PubMed1985

[Purely phasic neurons of the medial geniculate body--markers of changes in the signal].

The majority of neurons in the medial geniculate body responded with short bursts of activity to increments of the noise signal, and some of them--to decrements of the signal as well. Responses to changes in the signal envelope were only observed in narrow intensity range different for different neurons. The data suggest that division of neurons into groups acting within local dynamic ranges related to the cochlear nerve level, remains on the medial geniculate body level so as the ability of the organism to detect small changes in the signal envelope is maintained by the convergence of information from local detectors.

Animals↗
PubMed1980

Doctors' discussion.

On this evening four cases were discussed. Case One concerned a young boy who was first seen at the OMG at 6 months of age with severe hearing loss since birth. A lively discussion followed on whether a hearing aid could improve hearing by stimulation of the cochlear nerve. Case Two is that of a 14-year-old boy who was first seen at the OMG at the age of 9 years with complete paralysis of the left side of his face since he was 5 months of age. An interesting discussion of what might be done to alleviate the child's paralysis after a negative exploration of the nerve was included. Case Three involves a 10-year-old girl with an only hearing ear whose mother felt that a hearing aid would worsen hearing. A discussion of the sensitivity of ears owing to recruitment in patients with Meniere's disease follows this case. Case Four is that of a 36-year-old stewardess who was subjected to a rapid decompression while on a routine airline flight.

Adolescent↗
PubMed1978

[Auditory prosthesis (author's transl)].

1. Replacement of a non-functioning cochlea by a prosthetic device appears to be quite feasible. 2. In their current form, such prostheses provide only a rudimentary auditory perception, permitting discrimination of some simple noises, but providing substantial aid in lip reading. Speech perception is limited to a few words. 3. Further improvements of the prosthesis must take the patho-physiological situation into account: (a) It will be necessary to establish connections between individual electrodes and limited groups of cochlear nerve fibers so as to achieve a correct space/time/amplitude distribution of the applied signals; (b) signal components which are to be transmitted to selected nerve-fiber groups have to be encoded in such a way that they can be correctly processed by those fibers. 4. Only the future will show if the current prosthesis can still be improved. Even if one assumes that substantial improvements can be made, it is doubtful that "normal" speech perception can be restored.

Animals↗
PubMed1980

[Frequency characteristics of the masking effect: relationship between the characteristic variation factor and the frequency of the tone being masked].

The irregularity coefficient of the frequency characteristics of masking effect is a function of the frequency of masking tone with constant intensity (10 dB SL). The coefficient is growing by 9--12 dB per octave of the masking tone reaching 60 dB at the frequency 10 kHz. Similar dependence was found by measuring the frequency threshold curves of the cochlear nerve fibers. These values of the coefficient could not be obtained with the aid of classical model of the cochlea.

Auditory Perception↗
PubMed1995

[Analysis of antigenity of membranous labyrinth proteins of guinea pigs].

An electrophoretic dot immunobinding assay and a modified western blotting method were established. The components and antigenity of the membranous labyrinth proteins of guinea pigs were analysed. There are the same epitopes between some components of the antigen, between the antigen and extractives of acoustic nerve, cochlear nuclei, kidney and Klebsiella pneumoniae. The antigen distributes in stria vascularis, spiral ligament, spiral ganglion, the organ of Corti and Reissner's membrane etc.

Animals↗