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At least 667 records · Page 37Linked to original sources
PubMed1997

Prognostic factors in intraoperative facial nerve monitoring for acoustic neuroma.

OBJECTIVES: To determine the predictive value of intraoperative threshold stimulus for facial nerve outcome and the prevalence and prognostic value of persistent trains of activity and frequent spontaneous or mechanically induced contractions during acoustic neuroma surgery. STUDY DESIGN: Prospective recording and subsequent review of facial nerve activity. SETTING: Tertiary referral centre. PATIENTS AND METHODS: Consecutive patients undergoing acoustic neuroma surgery. Intraoperative facial nerve activity was digitised and stored on a personal computer for future analysis. Operative events were flagged. Recordings were available in 27 patients. MAIN OUTCOME MEASURES: Frequent mechanically induced contractions (< 20), prolonged trains of facial nerve activity (total time > 199 seconds), and facial nerve brainstem stimulus threshold were correlated with facial nerve outcome. RESULTS: A brainstem stimulus threshold > 0.1 mA was significantly associated with intermediate or poor facial nerve function (House-Brackmann grade > 2) on the sixth postoperative day, at 1 month and 6 months. Patients with normal or near-normal facial function on the first day and a threshold of > 0.1 mA were significantly more likely to develop a delayed facial nerve palsy. Frequent contractions were noted in 74% of patients and persistent train activity in 59%. Neither was predictive of facial nerve outcome. CONCLUSIONS: An elevated brainstem threshold is helpful in predicting delayed facial nerve palsy and suboptimal facial nerve outcome. Persistent train activity and frequent contractions, do not have major prognostic significance.

Adult↗
PubMed1997

[History of the tuning fork. I: Invention of the tuning fork, its course in music and natural sciences. Pictures from the history of otorhinolaryngology, presented by instruments from the collection of the Ingolstadt German Medical History Museum].

BACKGROUND: G. Cardano, physician, mathematician, and astrologer in Pavia, Italy, in 1550 described how sound may be perceived through the skull. A few years later H. Capivacci, also a physician in Padua, realized that this phenomenon might be used as a diagnostic tool for differentiating between hearing disorders located either in the middle ear or in the acoustic nerve. The German physician G. C. Schelhammer in 1684 was the first to use a common cutlery fork in further developing the experiments initiated by Cardano and Capivacci. For a long time to come, however, there was no demand for this in practical otology. THE INVENTION OF THE TUNING FORK: The tuning fork was invented in 1711 by John Shore, trumpeter and lutenist to H. Purcell and G.F. Händel in London. A picture of Händel's own tuning fork, probably the oldest tuning fork in existence, is presented here for the first time. There are a number of anecdotes connected with the inventor of the tuning fork, using plays on words involving the name Shore, and mixing up pitch-pipe and pitchfork. Some of these are related here. The tuning fork as a musical instrument soon became a success throughout Europe. THE PHYSICS OF THE TUNING FORK: The German physicist E. F. F. Chladni in Wittenberg around 1800 was the first to systematically investigate the mode of vibration of the tuning fork with its nodal points. Besides this, he and others tried to construct a complete musical instrument based on sets of tuning forks, which, however, were not widely accepted. J. H. Scheibler in Germany in 1834 presented a set of 54 tuning forks covering the range from 220 Hz to 440 Hz, at intervals of 4 Hz. J. Lissajous in Paris constructed a very elaborate tuning fork with a resonance box, which was intended to represent the international standard of the musical note A with 435 vibrations per second, but this remained controversial. K. R. Koenig, a German physicist living in Paris, invented a tuning fork which was kept in continuous vibration by a clockwork. H. Helmholtz, physiologist in Heidelberg, in 1863 used sets of electromagnetically powered tuning forks for his famous experiments on the sensations of tone. Until the invention of the electronic valve, tuning forks remained indispensible instruments for producing defined sinusoidal vibrations. The history of this development is presented in detail. The diagnostic use of the tuning fork in otology will be described in a separate article.

Acoustics↗
PubMed1977

Distinct auditory and lateral line nuclei in the midbrain catfishes.

The catfish torus semicircularis (TS) comprises two major nuclei, which are specialized to process separately inputs of three acousticolateral modalities: VIII nerve acoustic input in one, and lateral line mechanoreceptive and electroreceptive input in the other. Electrophysiological recording and mapping experiments demonstrate a medial auditory region, a lateral electroreceptive region, and an intercalated mechanoreceptive region in the TS Nissl and Golgi-Cox preparations distinguished two rostrocaudally elongate, nuclear divisions, which correlate, one with the auditory and the other with the mechano- and electroreceptive regions. The medially positioned auditory nucleus is here called the nucleus centralis. The nucleus centralis appears as a rostrally flattened cylinder of uniformly packed cells, covered dorsally and laterally by a fiber rind. Cells within this nucleus conform to one of three general cell types based upon somatic and dendritic morphology: type 1 cells, which are the most abundant" have a single major primary dendrite and an axon typically arising from the same somatic pole; type 2 cells have two major primary dendrites and an axon, which issues from a third distinct somatic pole; and type 3 cells have several major primary dendrites and their axons are associated with one of the major somatic poles. No systematic orientation of dendrites could be found in the nucleus centralis. The laterally positioned lateral line nucleus, to be called the nucleus lateralis, includes two subdivisions: a large pars lateralis containing predominantly electroreceptive units, and a smaller, ventromedial pars medialis encompassing predominantly mechanoreceptive units. Each subdivision is found to be somatotopically organized, inputs from the head projecting to rostral areas and inputs from the tail to caudal areas. Although the cell types resemble those described for the nucleus centralis, a greater degree of cytoarchitectural orderliness is discernible: (a) cells in the nucleus lateralis group into four, alternating cell-poor cell-rich, layers; and (b) the dendritic fields of many type 1 and type 2 cells located in layer II tend to orient in a rostrodorsal-caudoventral attitude, perpendicular to the laminar planes. Fink-Heimer preparations of brains with unilateral, lateral line lobe lesions demonstrate heavy fiber and terminal degeneration confined to the nucleus lateralis on both sides. Lateral line fibers ascend bilaterally in the lateral halves of the lateral lemnisci. At the level of the dorsal oculomotor nucleus the lemniscal fibers in this portion split into two fascicles, one proceeding rostrally to innervate the rostral portion of the nucleus lateralis, and the other arching back dorsolaterally to innervate the caudal portions of the nucleus.

Animals↗
PubMed2002

A method for the direct electrical stimulation of the auditory system in deaf subjects: a functional magnetic resonance imaging study.

PURPOSE: To develop a safe functional magnetic resonance imaging (fMRI) procedure for auditory assessment of deaf subjects. MATERIALS AND METHODS: A gold-plated tungsten electrode has been developed which has zero magnetic susceptibility. Used with carbon leads and a carbon reference pad, it enables safe, distortion-free fMRI studies of deaf subjects following direct electrical stimulation of the acoustic nerve. Minor pickup of the radio frequency (RF) pulses by the electrode assembly is difficult to eliminate, and a SPARSE acquisition sequence is used to avoid any effects of unintentional auditory nerve stimulation. RESULTS: The procedure is demonstrated in a deaf volunteer. Activation is observed in the contralateral but not the ipsilateral primary auditory cortex. This is in sharp contrast to studies of auditory processing in hearing subjects, but consistent with the small number of previous positron emission tomography (PET) and MR studies on adult deaf subjects. CONCLUSION: The fMRI procedure is able to demonstrate whether the auditory pathway is fully intact, and may provide a useful method for preoperative assessment of candidates for cochlear implantation.

Adult↗
PubMed1996

Different effects of noise and salicylate and their interactions on the guinea pig cochlea.

We investigated the effects of noise and salicylate on the guinea pig cochlea by monitoring the acoustic nerve compound action potential (CAP) as well as the 2f1-f2 distortion product in the cochlear microphonics (DP-CM). The alterations of DP-CMs by noise and salicylate revealed an apparent difference, even when the noise-induced and salicylate-induced CAP threshold shifts were equal. This result indicated that noise and salicylate might have an effect on different sites in the cochlea. Combined effects were altered by changing the order in which the two agents were applied. The existing noise-induced damage attenuated the additional ototoxicity of salicylate. In contrast, attenuation did not occur when salicylate administration preceded noise exposure. Considering known effects of noise and/or salicylate altering mechano-electrical transduction (MET) and electro-mechanical transduction of the cochlear outer hair cells, our results seem to suggest that the MET plays a key role in the transduction mechanism in the cochlea.

Animals↗
PubMed1984

Early auditory evoked potentials: developmental aspects and validity in neuropaediatric and audiologic disorders.

Auditory evoked potentials and in this context especially five waves in the first 10 ms (early auditory evoked potentials = EAEP) are a diagnostic aid in topodiagnosis of posterior fossa diseases. This is due to waves I to V which arise along the acoustic nerve and in brain stem structures such as medulla, pons and mid-brain. Besides an indication about the site of a lesion in the posterior fossa, wave V allows an objective threshold determination. The present results were gained in normal children aged 1-3 years and in children with neuropaediatric and audiologic disorders.

Adolescent↗
PubMed1982

Frequency-dependence of early auditory evoked responses in the guinea pig.

Neural auditory responses in the guinea pig, monitored by surface electrodes (brain stem potentials and frequency-following responses) and by electrodes at the round window, were analyzed for evidence of frequency dependence in the range from 500 Hz to 15 kHz. The characteristics of the brain stem potentials and frequency-following responses with stimuli near threshold intensity for frequencies below 2 kHz indicate that this activity derives from the excitation of apical regions of the basilar membrane. The same interpretation applies to the potentials recorded at the round window. Comparison of the responses seen with surface electrodes and those appearing at the round window reveals that the broad potential PI of the brain stem response to low-frequency stimuli corresponds to the compound action potential, while the frequency-following responses correspond to phase-locked responses in the acoustic nerve.

Animals↗
PubMed1989

Magnetic resonance imaging of jugular foramen neurinomas.

Four cases of jugular foramen neurinoma, extending from the posterior fossa into the temporal bone through the jugular foramen, are reported. The information provided by magnetic resonance imaging was compared with that by computed tomography. Due to the excellent sensitivity, the absence of bone artifacts, and the ease of imaging in any plane, magnetic resonance imaging gave better information particularly about the location of the tumour than X-CT scan did. It included the dumb-bell shaped tumour through the jugular foramen, the extra-axial nature of the tumour, and the precise anatomical relationships between the tumour and the facial and acoustic nerves or the internal carotid artery. Sagittal and coronal views clearly demonstrated the superior and inferior margins of the tumour. The information is very useful not only for preoperative diagnosis but also for planning the surgical approaches and postoperative follow-up.

Adult↗
PubMed2005

Middle cranial fossa arachnoid cysts causing sensorineural hearing loss.

Arachnoid cyst of the middle cranial fossa has never been reported to present with sensorineural hearing impairment. We report the case of a 15-year-old girl who complained of progressive hearing loss on the right side for 4 years. The pure tone audiometry revealed sensorineural hearing loss with an average of 63 dB, and the auditory brain stem response demonstrated absence of all waves on the right side. Magnetic resonance imaging showed giant arachnoid cysts occupying the bilateral middle cranial fossa and extending to the parietal and prepontine areas with the atrophic change of the right facial-acoustic nerve cord and a decrease in signal intensity of the right cochlea and vestibule. The cystoperitoneal shunting procedure was suggested, but the parents hesitated about the surgical treatment. The patient has not received any surgical intervention, and her hearing has been stable for 1 year during the follow-up period. This case represents the first report that sensorineural hearing loss is a possible presenting symptom when arachnoid cysts of the middle cranial fossa are massive.

Adolescent↗
PubMed2000

Therapeutic considerations in cerebellopontine angle lipomas inducing hemifacial spasm.

Lipoma is a very rare tumour at the cerebellopontine angle. We report a case of incomplete hemifacial spasm, associated with a lipoma involving and compressing both facial and acoustic nerves at their origin in the brainstem. The patient was treated with medical therapy (botulinum toxin A) and surgery. We present a review of the last ten years of the literature, with particular regard to management.

Botulinum Toxins, Type A↗
PubMed2006

A pediatric patient with neuro-Behçet's disease.

Behçet's disease is rare in childhood. We describe a 10-year-old boy with neuro-Behçet's disease (NB) who presented with fever, headache, vertigo, and hearing loss. An examination of the cerebrospinal fluid (CSF) revealed pleocytosis as well as elevated protein and interleukin (IL)-6 levels. Brain magnetic resonance imaging (MRI) showed hyperintensity of the right thalamus and midbrain on T2-WI, and gadolinium (Gd) enhancement of left acoustic nerve origin. HLA-B51 was positive. Prednisolone combined with methotrexate resulted in a complete remission. Brain MRI and the CSF IL-6 level were useful for the diagnosis and monitoring of this pediatric patient with NB.

Behcet Syndrome↗
PubMed1987

Clinical neurophysiological examination of deafness associated with juvenile motor neurone disease.

Three patients with the syndrome of progressive severe deafness, associated with juvenile onset of motor neurone disease, were examined using conventional audiometry and brainstem auditory evoked response (BAER) recordings, and electrocochleographic recordings were made in two of them. Findings indicate that the deafness had resulted from loss of acoustic nerve fibers and/or sensory cells of the spiral ganglion.

Adolescent↗
PubMed1981

Subarachnoid hemorrhage due to trigeminal neurinoma.

A patient with the initial symptoms of trigeminal neuralgia suddenly developed facial and acoustic nerve palsies after experiencing a spontaneous subarachnoid hemorrhage. The cause of the hemorrhage was found when a trigeminal neurinoma with an old intracapsular hematoma was exposed.

Adult↗