SEARCH · PubMed Health

Results for “NERVES, ACOUSTIC”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources

PubMed1982

The petrous temporal bone (including the cerebellopontine angle).

Lower resolution CT scanners play an important role in the evaluation of the cerebellopontine angle, but careful integration along with the older conventional examinations is often necessary. A high-resolution CT scanner may provide all the necessary information. With proper techniques, bony changes are most clearly analyzed, and small tumors of the acoustic nerve may be directly seen in the cerebellopontine angle, and even in the internal auditory canal, with only a contrast-enhanced scan. If necessary CT-air cisternography provides the most sensitive and least morbid of the definitive, invasive examinations. In scanning only a localized region, care must be taken not to overlook abnormalities just beyond the immediate cerebellopontine angle, either within the posterior fossa or the petrous temporal bone.

Cerebellopontine Angle↗

PubMed2000

Neurogenin 1 null mutant ears develop fewer, morphologically normal hair cells in smaller sensory epithelia devoid of innervation.

The proneuronal gene neurogenin 1 (ngn1) is essential for development of the inner-ear sensory neurons that are completely absent in ngn1 null mutants. Neither afferent, efferent, nor autonomic nerve fibers were detected in the ears of ngn1 null mutants. We suggest that efferent and autonomic fibers are lost secondarily to the absence of afferents. In this article we show that ngn1 null mutants develop smaller sensory epithelia with morphologically normal hair cells. In particular, the saccule is reduced dramatically and forms only a small recess with few hair cells along a duct connecting the utricle with the cochlea. Hair cells of newborn ngn1 null mutants show no structural abnormalities, suggesting that embryonic development of hair cells is independent of innervation. However, the less regular pattern of dispersal within sensory epithelia may be caused by some effects of afferents or to the stunted growth of the sensory epithelia. Tracing of facial and stato-acoustic nerves in control and ngn1 null mutants showed that only the distal, epibranchial, placode-derived sensory neurons of the geniculate ganglion exist in mutants. Tracing further showed that these geniculate ganglion neurons project exclusively to the solitary tract. In addition to the normal complement of facial branchial and visceral motoneurons, ngnl null mutants have some trigeminal motoneurons and contralateral inner-ear efferents projecting, at least temporarily, through the facial nerve. These data suggest that some neurons in the brainstem (e.g., inner-ear efferents, trigeminal motoneurons) require afferents to grow along and redirect to ectopic cranial nerve roots in the absence of their corresponding sensory roots.

Animals↗

PubMed1997

Auditory evoked responses under total spinal anesthesia in rats.

In order to investigate the function of the auditory pathway from the cochlea to the brain stem under total spinal anesthesia, the auditory brain stem response (ABR), compound action potential of the cochlear nerve (CAP), and cochlear microphonics (CM) were simultaneously recorded in rats. Total spinal anesthesia was induced by infusion of 2% lidocaine hydrochloride at a constant rate of 0.10 mL/min into the cerebrospinal fluid through the rats' skulls. The ABR completely disappeared within 1.5 to 4 minutes. After cessation of the injection, the ABR reappeared, starting from wave I and progressing through waves II and III to wave IV. The latency change of the CAP throughout the recording period was quite similar to that of wave I of the ABR. A reduction in amplitude of the CM was observed, but the CM did not disappear during the recording period. Disappearance of the ABR was due, not to loss of cochlear function, but to anesthetic effects on the acoustic nerve and the brain stem. Monitoring of the ABR provided information on the level of neural activity in the brain stem under total spinal anesthesia.

Action Potentials↗

PubMed1998

Brain stem frequency-following response to dichotic vowels during attention.

Frequency-following responses (FFRs) were elicited by English long vowels (female /a/ and male /e/) in a dichotic listening task. Stimuli were simultaneous and of equal duration, but differing spectra permitted unique identification of vowel components in the compound FFR. Horizontal and vertical montage FFRs were recorded with putative origins in the acoustic nerve and central brain stem, respectively. FFRs obtained during attention to each vowel showed significant effects for the voice fundamental frequency, f0, which is perceptually salient and conveys paralinguistic information such as the sex of the speaker. Amplitudes of f0 were larger when vowels were attended than when ignored. These findings provide evidence of short-latency attention effects in humans and suggest that linguistic attention may initially filter inputs based on salient paralinguistic cues.

Acoustic Stimulation↗

PubMed1977

Auditory evoked brain stem potentials in a case of "locked-in" syndrome.

Auditory evoked brain stem potentials were measured in a patient with occlusion of the basilar artery about 7 mm above its origin, resulting in the "locked-in" syndrome due to infarction at the junction of the lower one third and upper two thirds of the pons. The first three waves of the evoked response originating from the acoustic nerve and auditory nuclei in the caudal pons were normal in wave form, peak latency, and voltage level. Waves IV and V, generated in the region of the lateral lemniscus and inferior colliculus in rostral pons and caudal midbrain, demonstrated prolonged peak latency and reduced voltage, indicative of slowed neural conduction in the pons above the level of the superior olivary complex. These findings suggest that auditory evoked potential recordings may have considerable value in the localization of brain stem disorders.

Acoustic Stimulation↗

PubMed1977

Neuroanatomical aspects of the gerbil inner ear: light microscope observations.

A specialization of the Mongolian gerbil inner ear allows easy access for electrophysiological recording from the auditory nerve and other structures of the internal auditory meatus. The round-window membrane is recessed, creating a cavity connecting the bulla and the external wall of the modiolus. This cavity has been named the round-window antrum. A small opening made in the dorsomedial wall of the round-window antrum gives access directly to the modiolus and internal auditory meatus, with no other openings in the cranium required. This surgery is less drastic than that needed for similar access in most other mammals. The anatomy of the specialized region is presented from studies with the light microscope. Emphasis is placed on the relationship between external features of the wall of the round-window antrum and the internal anatomy of the modiolus and internal auditory meatus. In addition, these studies reveal that cell bodies of the acoustic-nerve nucleus are located in the auditory nerve, central to the glial dome. About 22 +/- 8 cells are found in an auditory nerve. Their appearance with a Nissl stain is similar to cells found in rat, mouse, and man. The cell dendrites are preferentially oriented perpendicular to the longitudinal course of the auditory-nerve fibers. The anatomy of the gerbil auditory system should allow direct electrophysiological recording from these cells.

Animals↗

PubMed2001

Functional magnetic resonance imaging of human pontine auditory pathway.

The purpose of this study is to visualize brainstem auditory pathways by functional magnetic resonance imaging (fMRI). Eighteen healthy volunteers (age 28 to 42 years) with normal hearing function underwent fMRI examination on a 1.5 Tesla imaging system (Philips, Best, The Netherlands) with periodic click stimulation. Blood oxygen level dependent images were obtained using a three-dimensional EPI sequence with shifted echo technique (principles of echo shifting with a train of observations). Control scans without click stimulation were obtained in the identical setting. Cross correlation activation maps were calculated using a postprocessing tool (Philips). They were matched with anatomic slices of identical orientation and thickness. Five of 18 subjects were excluded because of motion artifacts. In 4/13 significant activation was observed at the root entry zone of the ipsilateral acoustic nerve corresponding to the cochlear nuclei. In 11/13 subjects, significant activation was found in the same slice contralaterally close to the floor of the 4th ventricle, corresponding to the expected region of the superior olivary nucleus. Activation of the rostral parts of the auditory pathway (inferior colliculus, medial geniculate body) was not found. In the absence of the stimulus no activation occurred in these structures. It was concluded that activation of the brainstem auditory pathways by click stimuli can be visualized by fMRI.

Acoustic Stimulation↗

PubMed1998

[The neurodystrophic component of the structural changes in the hemispheric cerebellar cortex of patients with acoustic neurinomas].

Cerebellar specimens removed in surgical treatment of acoustic nerve neurinomas were studied morphologically in 16 patients. Histochemically, morphofunctional state of the vegetative adrenergic nervous fibers and endings of the vessels and connective tissue basis of the pia mater encephali in the region of the cerebellum indicates inhibited activity of the neuromediator contour of circulation and metabolism regulation in the brain. Light and electron microscopy in the cerebellar cortex detected disorders of circulation, nervous cell dystrophy, glyocytic proliferation. Correlation was found between activity of sympathetic component of the autonomic nervous system, severity of neurodystrophic changes in the cerebellar cortex and development of pathophysiological reactions arising intraoperatively and early after operation.

Cerebellar Cortex↗

PubMed1984

[Experimental study on the effect of ultrasonic surgical aspiration on blood flow and nerve function by use of ultrasonic Doppler flowmeter and auditory brainstem evoked response].

The effect of intracranial use of an ultrasonic surgical aspirator on major cerebral vessels and nervous tissue was studied in anesthetised adult cats. Experiments were performed without suction in order to investigate only the effect of ultrasonic emulsification. The flow rate of irrigation saline over the tip of the ultrasonic aspirator was set at either slow (4 ml/min) or fast (24 ml/min). Flow in the common carotid artery and superior sagittal sinus was studied by ultrasonic Doppler flowmetry during direct or indirect (intermediated by muscle fragment) application to the vessels of ultrasonic vibration for periods of 5 min. each in increments of 20% from 20% of maximal intensity. Flow in both the carotid artery and the superior sagittal sinus changed only with direct application on vascular surface of ultrasonic vibration of at least 80% of maximal intensity; otherwise flow in these vessels was not changed. The temperature rise caused by ultrasonic vibration was studied by use of a thermister buried in the brain parenchyma of animals 2 mm from the ultrasonic vibratory probe tip. A rise above the physiological range could be prevented by sufficient irrigation. The effect of ultrasonic vibration on the brainstem was studied by using auditory brainstem evoked response (ABR) to monitor brainstem function. An ultrasonic vibratory probe was applied to the ventral surface of the brainstem exposed by transclival approach. ABR changed noticeably only when ultrasonic vibration of 60% or more of maximal intensity was applied directly; otherwise ABR was not changed. The effect of ultrasonic vibration on the intracranial acoustic nerve was also studied by ABR.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Intracanalicular neurilemmomas: clinicopathologic study.

Twenty-five patients with intracanalicular neurilemmonas were studied, the largest series yet reported. The tumors were most frequent in men by a ratio of 2:1, occurred more often on the left acoustic nerve, generally associated with long duration of symptoms and were equally distributed in the third to fifth decades, but the prevalence slightly increased in the sixth and seventh decades. A shorter length of illness occurred in younger persons as well as most patients with von Recklinghausen's disease. The length of illness ranged from six months to 35 years. Symptoms generally were limited to the auditory nerve except in three instances of involvement of the facial nerve. These three cases were the only ones with preoperative facial palsy. Posterior fossa myelogram was the most useful diagnostic acid. The rate of growth in one patient was estimated to be 1 to 2 mm per year by serial study of myelograms, but the growth rate is probably variable. CT scans were not useful in detecting small tumors. Histologically, most tumors less than 1 cm in diameter were primarily composed of Antoni type A tissue. Vascular malformations were found within the tumor in three cases. Altered blood vessels are the mechanism whereby characteristic changes occur in the cerebrospinal fluid (CSF). Small tumors generally lack blood vessels, hence are less often associated with abnormal CSF.

Adolescent↗

PubMed1977

Detection and localization of occult lesions with brainstem auditory responses.

Seven vertex-positive potentials--the brainstem auditory response--can be recorded from the human scalp within 10 milliseconds of an appropriate acoustic stimulus. The first of these potentials is generated in the acoustic nerve, the third in the pons, and the fifth in the midbrain. Measurement of the relative latencies and amplitudes of these potentials allowed detection of subclinical lesions in 37 (53 percent) of 70 patients with suspected multiple sclerosis who had no signs or symptoms of brainstem involvement by the disease. Abnormalities in the brainstem auditory response provided the first evidence of the pressence of multiple lesions in 14 (35 percent) of 40 patients with suspected multiple sclerosis who had clinical evidence of only a single spinal or cerebral lesion. Response abnormalities also suggested the presence of tumors of the posterior fossa in three patients with nonspecific symptoms and normal neurologic examinations, the test indicated the need for contrast studies, which then led to the correct diagnosis of infratentorial neoplasm.

Acoustic Stimulation↗

PubMedDate not supplied

[Using brainstem auditory evoked potentials in cerebellopontine angle tumors (author's transl)].

The brainstem electric responses on acoustic stimulation are recorded on 37 patients with verified cerebellopontine angle tumors. These responses are compared with those of 101 normal hearing young adults and those of 47 patients with cochlear hearing loss. The Interval between the latency of the first wawe (acoustic nerve) and the fifth (midbrain) or I-V delay is related to the lesion location. The I-V delay is increased in retro-cochlear hearing loss and not different of the normal in cochlear hearing loss. The delay variation is best seen by comparing the I-V delay for the two ears. The interaural I-V delay difference (ITI-V) is normally less than 0,3 msec and is greater than or equal to 0,35 ms in the tumor group. The use of ITI-V increases the reliability of the test. We have neither false positive nor false negative findings. We now use brainstem electric responses as a routine part of our office practice of neuro-otology.

Adult↗

PubMedDate not supplied

[The point of view of the radiotherapist].

During the last decade, stereotactic radiotherapy has widely improved in France. Thus one should study the present situation and its future trend. QUANTITATIVE NEED: Considering single dose radiotherapy, there are about 900 to 1,000 cases treated per year. However, the trend towards more fractionated treatment will disturb this temporary equilibrium; thus more machine time will be necessary. QUALITATIVE NEED: Stereotactic radiotherapy is practiced by multi-disciplinary teams including physicians, physicists and scientific specialists. Radiotherapists and physicist are responsible for treatment planning and evaluation as well as for clinical and methodological research. Accordingly, they should possess computers, treatment planning systems, etc. Such teams are necessary to carry out complex irradiations. GENERAL EVOLUTION: Fractionation of irradiation nowadays seems mandatory for most intracranial tumors except metastases and small regular arteriovenous malformations. Heterogeneity of lesion dose is related to the geometry and the physics of convergent fixed or mobile beams. It can be improved and the healthy tissue irradiation can be diminished using the multi-isocentric planning for complex lesion or with micro multi leaf collimators. MODALITIES OF STEREOTACTIC RADIOTHERAPY ACCORDING TO LESION TYPE: For neurinomas of the acoustic nerve, fractionated stereotactic radiotherapy yields few of the complications published after single dose stereotactic radiotherapy. The same can be said for meningiomas although some series reported very few complications after single dose stereotactic radiotherapy. Solitary metastases without systemic evolution, not situated on the mid-line, are favorable candidates for palliative single dose stereotactic radiotherapy. The conjunction with total brain irradiation seems to be useful. Small arteriovenous malformations will be treated with single dose stereotactic radiotherapy, whereas voluminous and/or geometrically complex nidus could benefit from protons or photon beams modulated by micro multi leaf collimators and a few fractions. EXTRA-CRANIAL STEREOTACTIC RADIOTHERAPY: Single dose stereotactic radiotherapy and fractionated stereotactic radiotherapy will be used as boost in various situations such as massif facial and in all sorts of tumors in the body specially when lesions are close to critical organs.

Brain Neoplasms↗

PubMed1980

Brain stem auditory evoked response development in the kitten.

The development of brain stem auditory evoked responses (BAERs), recorded from a surface electrode as short-latency, volume-conducted potentials, was studied in a series of kittens over a postnatal period ranging from birth to 60 days. Repeated, longitudinal observations on particular kittens were supplemented with observations on additional kittens during the first and second postnatal week to determine age of onset of the BAERs. The position of the animal and sound source within the recording chamber were held constant across recording sessions, as was click intensity except during recordings in which intensity effects were specifically studied. Click rates of 1, 10, 50 and 100/sec were routinely presented. Reference electrodes at the tongue, pinna and neck showed volume-conducted responses to the click stimuli and resulted in considerable distortion of the activity recorded by the vertex electrode; the forepaw, in contrast, showed no activity and a vertex-forepaw electrode configuration provided good resolution of the BAERs across development. A number of new observations were made. BAERs were first observed at 4 days of age, approximately the same age at which depth evoked potentials are first recorded in brain stem auditory nuclei. Initially the BAERs were diffuse, high threshold and fatigued rapidly, characteristics shared with depth evoked potentials in the early postnatal period. Over the first two weeks, the potentials showed marked decrease in threshold, increased resistance to fast click rates, and better definition of wave forms. All BAER components showed exponential decreases in latency. Because all of the brain stem evoked potentials could be recorded concurrently and longitudinally in the same subject a number of developmental comparisons were possible among the BAER components. Wave 1, related to the acoustic nerve in the adult cat, showed a developmental time course and adult latency similar to that reported for N1. Wave 2, related to the cochlear nucleus in the adult, showed a marked bimodality over the first month; wave 2a was a large amplitude clearly separated wave which gradually fused as an inconspicuous leading shoulder on wave 2b. Wave 2b developed with a time course and adult latency similar to that reported for the ventral cochlear nucleus. Wave 3, related to the region of the superior olivary complex in the adult, showed a clear but transient bimodality during the third week of development. Wave 5, related to the inferior colliculus in the adult, appeared later than waves 1-4 and showed a significantly slower rate of development than waves 1-4. These data indicate that differential developmental changes occur within the brain stem auditory pathway and that the BAERs provide a dynamic probe of concurrent maturational interactions.

Acoustic Stimulation↗

PubMed1989

[Audiometry findings, speech, impedance audiometry and BERA in acoustic neurinoma].

Audiometric examinations are essential in the diagnosis of acoustic neuroma. Experience with the diagnosis of 41 neurinomas of the acoustic nerve show, however, that the tactics of audiometric examinations vary from one case to the other. The basic examination is in all instances an accurate examination of the threshold of hearing. When the threshold is normal or there are slight or medium severe losses on the side of the lesion, the tympanogram, impedance and speech audiometry and BERA are supreme examinations and all other audiometric examinations are redundant. For BERA alone limiting losses are above 3000 to 4000 Hz. As soon as they pass at the above frequencies the borderline of 60 dB HL in proportion to the magnitude of these losses the amount of falsely positive findings increases rapidly and the importance of BERA in the diagnosis declines. The same applies to impedance audiometry if major losses interfere with medium and lower frequencies. In all these instances the importance of speech audiometry as well as of STAT (Supra Threshold Adaptation Test) increases, i.e. of traditional audiometric examinations, the latter of which can be used successfully also in very high losses round 80-90 dB HL.

Acoustic Impedance Tests↗

PubMed1990

Immunohistochemical localization of vimentin and S-100 antigen in small acoustic tumors and adjacent cochlear nerves.

To clarify the involvement of cochlear nerves in small acoustic tumors, we used immunoperoxidase techniques to determine the presence and distribution of vimentin and S-100 antigens in two acoustic tumor specimens and a transected vestibular nerve. Schwann cells and acoustic tumor cells failed to react positively with monoclonal antibody to vimentin. Reaction was observed in mesenchymal-appearing cells within both the normal nerve and the acoustic tumors, predominantly in association with blood vessels. Normal schwann cells and acoustic tumor cells reacted with polyclonal antibody to S-100 antigen with a similar, uniform distribution. Mesenchymal-appearing cells did not react with antibody to S-100. Immunostaining of a vestibular nerve from a Meniere's disease patient, used as a control, did not differ significantly from nerves adjacent to acoustic tumors. Because tumor cells and normal schwann cells stained similarly with antibody to S-100, it was not possible to establish with certainty if tumor cells invaded adjacent nerves.

Antigens, Neoplasm↗

PubMed2006

Age-related hearing loss in CD/1 mice is associated to ROS formation and HIF target proteins up-regulation in the cochlea.

Pathologies of senescence, in particular those of neurosensory organs represent an important health problem. The improvement of the life expectation entails the fast increase of the frequency of the age-related hearing loss (ARHL) in the population. There are numerous factors that contribute to this process, which include altered vascular characteristics, hypoxia/ischemia, genetic mutations and production of reactive oxygen species. We were interested in understanding the mechanisms involved in the cochlear degeneration in a mouse model of ARHL, the cd/1 mice. Since in human, hypoxia/ischemia is an important pathogenetic factor for inner ear disease, the regulation of HIF-1 activity in the cochlea, the presence of radical oxygen species in the cochlea and its subsequent disturbances of cellular signaling cascades were investigated. In this study, we explored auditory function of cd/1 mice at the age of 4, 12 and 24 weeks and correlated it with the presence of oxidative damage in the cochlea, and cochlear HIF-1 responsive target genes regulation, involved in pathways promoting inflammation such as tumor necrosis factor (TNF-alpha), or cell death with the p53 protein, Bax protein and surviving factors with insulin-like growth factor-1 (IGF-1). After implantation of electrodes for auditory nerve acoustic thresholds measurements, we analyzed every cochlea. First, we confirmed that the cd/1 mice presented a characteristic profile of ARHL starting at 12 weeks of age. Then, according to our previous report [Riva, C., Longuet, M., Lucciano, M., Magnan, J., Lavieille, J.P., 2005. Implication of mitochondrial apoptosis in neural degeneration in a murin model for presbyacusis. Rev. Laryngol. Otol. Rhinol. 126 (2), 67-74], we noticed many alterations in the cochlea. Histologically, at 4 weeks, intensive HIF-1alpha expression was detected in the cochlea followed by ROS formation at 12 weeks, which may lead to cochlear degeneration and induction the onset of ARHL in the cd/1 mice model. In the cochlea, while the inner and the outer hair cells remained intact at 4 and 12 weeks, the spiral ganglion was more altered. Moreover, the Schwann cells of the spiral ganglion seemed to be more vulnerable to free radical damage than the neurons and degenerated more rapidly. The mechanisms of degeneration in the spiral ganglion involved a caspase-3 and Bax mediated-apoptosis via p53 protein accumulation. Since oxygen radicals are required for the post-translational stabilization of HIF-1alpha during hypoxia, the tandem " HIF-ROS " induced multiple reactions within the cochlea, like a strong inflammatory response with increased expression of TNF-alpha, and inhibition of neuronal protection mechanisms with repression of IGF-1.

Action Potentials↗

PubMed2005

[Implication of mitochondrial apoptosis in neural degeneration of cochlea in a murine model for presbycusis].

HYPOTHESIS: Pathologies of senescence, in particular those of neurosensory organs represent an important health problem. The improvement of the life expectation entails the fast increase of the frequency of the presbyacusis in the population. The biological and molecular causes of this degenerative pathology of the inner ear are linked to the disappearance of the sensory cells (inner and outer hair cells) and are associated to nervous damages of the spiral ganglion in the cochlea. We were interested in mechanisms causing the cochlear degeneration in a model of mouse CD 1 presenting prematurely auditive losses. MATERIALS AND METHODS: We tried to correlate the evolution of the hearing and the appearance of apoptotic phenomena by marking with specific antibody, activated anti-caspase-3, in the cochlea during time. We studied the role and the involvement of proteins controlling the apoptosis as the P53 protein and from an energy point of view at the level of the mitochondria such as proteins of the Bcl-2 family and the cytochrome c in the various structures of the cochlea. RESULTS: After implantation of electrodes for auditory nerve acoustic thresholds measurements, the audition of mice CD 1 presented a characteristic profile of hearing losses which begins in the high frequencies from the age of 1 month and which quickly evolves towards the low frequencies. The observation (between the 1st and 3rd month of age) of spiral ganglion cells revealed an unchanged number of cellular bodies of type 1 neurons, on the other hand a characteristic morphology of apoptosis of glial cells with the formation of apoptotic body was noted. Indeed, glial cells expressed activated caspase-3. Furthermore, this phenomenon seems to be under the control of the pro-apoptotic protein Bax by its overexpression and a increased release of the cytochrome c. This phenomenon was followed at 3 and 6 months by the disappearance of the outer hair cells by 9 and 48% respectively. CONCLUSION: The apparition of the deafness in the murin model CD 1 allowed us to demonstrate that the degeneration of cochlear structure begins at the level of glial cells of the spiral ganglion from 3 months, followed thereafter by the deterioration of the nervous conduction between the spiral ganglion and the sensory cells. As a consequence, because of the impoverishment in nervous signals, the outer hair cells would begin to disappear during the 6th month. In conclusion, the understanding of the sequence and the cause of these mechanisms responsible for the neural degeneration and the loss of hearing could eventually, allow us to optimize the various treatments of the presbyacusis.

Adaptor Proteins, Signal Transducing↗