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At least 775 records · Page 43Linked to original sources
PubMed1992

Stereotactic radiosurgery in the treatment of patients with acoustic tumors.

Stereotactic radiosurgery is performed under local anesthesia, and most patients can be discharged from the hospital within 24 hours of treatment. All patients in our series returned to their preoperative level of employment or function within 5 to 7 days of treatment, and this functional level was maintained over the period of follow-up. "Tumor control" was achieved in 96% of patients during an average follow-up of 1.7 years. Tumor shrinkage occurred in 45% of patients who had at least 1.5 years of follow-up. Useful hearing preservation rates were 50% at 6 months and 30% 1 year after treatment. New delayed facial or trigeminal neuropathy occurred in 34% and 32% of patients, respectively, with a median onset of 5 to 6 months after treatment. The vast majority of cranial neuropathies were partial at onset and tended to improve over time. Other complications included tumor growth (4%), communicating hydrocephalus (4%), and transient adjacent brain parenchymal changes best seen on T2-weighted MRI (9%). Stereotactic radiosurgery is an important alternative treatment for carefully selected patients with acoustic tumors. Indications for treatment include sufficient medical problems to pose excessive surgical risk, advanced age, the presence of bilateral acoustic tumors or contralateral deafness, recurrent tumor despite surgical resection, or refusal to undergo microsurgery. Radiosurgery is contraindicated in patients with symptomatic brain stem or cerebellar compression from a large acoustic tumor. Previous posterior fossa radiotherapy is a relative contraindication that must be considered on a patient to patient basis. Stereotactic radiosurgery should be viewed as an additional weapon in our arsenal for combating acoustic tumors rather than feared as a potential replacement for surgical excision. The strategic role of stereotactic radiosurgery in the overall treatment of patients with acoustic tumors will continue to be refined as longer-term, carefully assessed results become available.

Adolescent↗
PubMed2005

[Assessment of voice acoustic parameters in female teachers with diagnosed occupational voice disorders].

BACKGROUND: Laryngovideostroboscopy is the method most frequently used in the assessment of voice disorders. However, the employment of quantitative methods, such as voice acoustic analysis, is essential for evaluating the effectiveness of prophylactic and therapeutic activities as well as for objective medical certification of larynx pathologies. The aim of this study was to examine voice acoustic parameters in female teachers with occupational voice diseases. MATERIALS AND METHODS: Acoustic analysis (IRIS software) was performed in 66 female teachers, including 35 teachers with occupational voice diseases and 31 with functional dysphonia. RESULTS: The teachers with occupational voice diseases presented the lower average fundamental frequency (193 Hz) compared to the group with functional dysphonia (209 Hz) and to the normative value (236 Hz), whereas other acoustic parameters did not differ significantly in both groups. CONCLUSIONS: Voice acoustic analysis, when applied separately from vocal loading, cannot be used as a testing method to verify the diagnosis of occupational voice disorders.

Adult↗
PubMed2006

Acoustic analysis of voice in patients treated by reconstructive subtotal laryngectomy. Evaluation and critical review.

Aim of this investigation was to analyse the voice in a group of 20 patients submitted to supracricoid partial laryngectomy (cricohyoidopexy, sparing two arytenoids) by the Multi Dimensional Voice Programme acoustic analysis system. Results revealed the following sound characteristics: high rate of noise, lack of periodic component of the signal, high rate of segments with no sound signal, vocal segments with marked air-turbulent flow, variation amplitude and frequency coefficients doubled compared to normal values, average fundamental frequency, if present, extremely variable and unsteady. These results show that the phonatory ability of the residual larynx, due to the altered anatomo-physiology of the structure after surgery, has to be completely re-estimated. In fact, the residual larynx determines a definitely reduced periodic acoustic signal, rich in noise and which can not be modulated. Good phonatory results of this treatment are basically due to preservation of a still understandable (but not perfect!) speech which, by ensuring the subjects' speech ability, overcomes and has little influence on the really poor quality of the vocal signal in these patients. However, the patient obtains a "new voice" as far as concerns acoustic features and this is very important for communication and social life. Moreover, the possibility of objectively estimating acoustic vocal function ability allows monitoring of the trend and results of possible speech therapy and/or phonosurgical rehabilitation treatment which should start from new anatomical and physiological bases, as well as from the new physical acoustic mechanism of signal production.

Aged↗
PubMed1989

The acoustic stimulation test in the anencephalus: preliminary results.

It is not yet clear whether the acoustic stimulus influences the fetus by auditory or vibrational pathways. The anencephalic fetus is an interesting model for the study of the pathway for receipt of acoustic stimulation because of the near absence of cerebral hemispheres. After the traditional nonstress test (NST), the response to acoustic stimulation was assessed in eight fetal heart rate (FHR) recordings of six anencephalic fetuses of gestational age between 18 and 39 weeks. Although four preterm fetuses demonstrated nonreactive results in the NST, two term fetuses revealed reactive NSTs. However, none of these six anencephalic fetuses responded to acoustic stimulation. These data suggest that the cerebral cortex is the origin or transmission route of the FHR response to acoustic stimulation. We hypothesize that the normal fetus might receive externally applied sounds via auditory pathways rather than vibratory pathways, at least in term pregnancy.

Acoustic Stimulation↗
PubMed1988

Diagnosis, size, and operation results in 41 acoustic neurinomas.

The diagnosis, size and operation results in 41 acoustic neurinomas (26 females and 15 males) are presented. In one case the tumor was bilateral. Out of the total of 41 tumors, 12.5% were small acoustic neurinomas. As a rule, at diagnosis the tumors were larger in females than in males. Ten of the small and medium size acoustic neurinomas had no brain stem and cerebellar symptoms or signs at all, only the 8th cranial nerve was affected. All large tumors already had brain stem symptoms and one-third of them also had cerebellar symptoms, lesions of further cranial nerves and increasing intracranial pressure. All these findings were always present in giant tumors. Neurootological functional laboratory examinations cannot be replaced by CT because of the possibility of false negative findings in the smallest acoustic neurinomas. CT and functional neurootological laboratory examinations are complementary to each other and they are not screening procedures at all. As regards morbidity and mortality, the surgical results are comparable with those of other authors using microsurgical techniques. As regards the preservation of hearing, the results are among the best particularly in tumors that were diagnosed as small or medium in this series. Thus it is apparent that the size of a diagnosed acoustic neurinoma is more important for surgical results than the chosen approach to the tumor.

Adolescent↗
PubMed1988

Evoked otoacoustic emissions in patients with acoustic neuromas.

Click-evoked otoacoustic emissions were recorded in 28 patients with surgically proven acoustic neuromas and 22 patients with brain stem pathologic disorders. Data collected in acoustic tumor ears were compared with those obtained in 30 nontumor ears demonstrating sensorineural hearing losses. Acoustic emissions were altered (increased detection-threshold or no detectable emissions) in all ears with eighth nerve tumors and were not affected in those with brain stem pathologic conditions that do not involve cochlear function. The properties of acoustic emissions were similar in both tumor and nontumor ears with hearing loss, which suggests that acoustic tumors usually produce a cochlear hearing loss.

Adult↗
PubMed1988

Otosclerosis masking coexistent acoustic neuroma.

The coexistence of an acoustic neuroma with otosclerosis can prove to be a great diagnostic dilemma. In such cases, the diagnosis of acoustic neuroma is usually delayed while more common causes of sensorineural hearing loss associated with otosclerosis or its surgery are considered. Any asymmetric progression of a sensorineural loss or shift in discrimination after stapes surgery, whether sudden or gradual, should provoke suspicion of a second pathologic process. These include perilymph fistula, labyrinthine otosclerosis or ischemia, and acoustic neuroma. The use of auditory brainstem response and acoustic reflex testing and various imaging techniques is essential for accurate diagnosis. This paper includes two cases that demonstrate this dual pathology, bringing the total to 15 such cases reported in the literature. The purposes of this paper are to alert the clinician to the diagnostic problem of acoustic neuroma coexisting with otosclerosis and to propose a means of evaluating these patients.

Adult↗
PubMed1987

Acoustic reflex dynamics and auditory brain stem responses in multiple sclerosis.

Onset latency, rise time, and amplitude measures of the acoustic reflex and auditory brain stem responses (ABRs) to clicks were elicited from normal subjects and subjects with multiple sclerosis (MS). The results indicated that MS subjects exhibited response abnormalities including prolonged rise times of the acoustic reflex and prolonged absolute latencies, interwave latencies and interaural latencies, and poor response stability of the ABR. The results of this study indicate that measurement of acoustic reflex dynamics can add to the diagnostic value of the test beyond measurement of acoustic reflex threshold and decay. The combination of complete acoustic reflex and ABR tests is a valuable contribution to the diagnosis of patients with MS who have no auditory symptoms.

Adult↗
PubMed1985

Conservative management of acoustic neuroma in the elderly patient.

A subtotal resection through the translabyrinthine approach should be used in the treatment of large symptomatic acoustic neuromas in patients over the age of 65. This approach will consistently relieve the patient's symptoms of brain stem compression, reduce postoperative morbidity and complications, and preserve facial nerve function. In the elderly, after subtotal resection, the remaining tumor in 80% of cases appears to remain dormant during the average six year follow-up (1-16 year range). Eighty percent of acoustic neuromas not operated upon, appear to grow at a slow rate (0.2 cm/yr) while 20% grow at a fast rate (1 cm/yr). Patients over the age of 65 with small acoustic neuromas do not need surgical intervention. Yearly CT scanning is recommended to determine the growth rate of the acoustic neuroma. A conservative approach should be used in the treatment of all acoustic neuromas in the elderly.

Age Factors↗
PubMedDate not supplied

Influence of ear canal air pressure on acoustic reflex threshold.

This study was undertaken to investigate the effects of ear canal air pressure variation on the threshold of acoustic reflex. The acoustic reflex threshold was obtained to 500 and 1000 Hz activating signals as pressure was varied between +/- 200 mm H2O. The results demonstrated a reduction in sensitivity of the acoustic reflex with variations in positive or negative air pressure. Observation of the conductance component of admittance consistently required higher intensity levels to elicit the acoustic reflex. Clinical implications are that external air pressure can vary within a range of +/- 80 mm H2O and continue to maintain the acoustic reflex threshold close to its value obtained at maximum compliance.

Adult↗
PubMedDate not supplied

Acoustic reflex thresholds using conventional and tracking methods.

Relationship between acoustic reflex thresholds obtained using conventional and tracking procedures was investigated. In the tracking method, the intensity of the stimulus from a self-recording audiometer is adjusted by the experimenter to bracket the acoustic reflex threshold as visually observed on the meter of an acoustic impedance measuring device. Acoustic reflex thresholds were obtained to pure tones of 500, 1000, and 4000 Hz. High correlations and no significant differences were obtained between the two threshold methods. It was concluded that the tracking method which allows easier control of stimulus parameters and response recording can provide acoustic reflex threshold data similar to those obtained using a conventional method.

Audiometry↗
PubMed1981

Cerebellar interaction with the acoustic reflex.

The involvement of the cerebellar vermis in the acoustic reflex was analyzed in 12 cats, decerebrated or in pentobarbital anesthesia. Anatomical data suggested the existence of a connection of lobules VIII with the ventral cochlear nucleus. Single cell recording and evoked potential techniques demonstrated the existence of the acoustic projection to lobulus VIII. Electrical stimulation of this area changed the tension of the middle ear muscle and caused evoked potential responses in the caudal part of the ventral cochlear nucleus. Electrical stimulation of the motor nucleus of the facial nerve evoked a slow wave in the recording taken from the surrounding of the cochlear round window. A hypothesis is proposed which postulates the involvement of the acoustic reflex in space localization of acoustic stimuli and the action of cerebellar vermis in order to assure the stability and plasticity of the acoustic reflex arc.

Animals↗
PubMed1983

A physiological study of acoustic blinking reflex in the cat.

Blinking reflex was elicited by acoustic stimulus to investigate the reflex pathway in the encéphalo isolé cat. Reflex responses were recorded using electromyography (EMG) of the orbicularis oculi. The investigation was as follows: After stimulation by a loud click sound, the EMGs of the orbicularis oculi were elicited bilaterally. Latencies were 17-20 msec on the ipsilateral side, and 19-21 msec on the contralateral side. By electrical stimulation of the peripheral nerve in the cochlea and the acoustic nerve EMGs were also obtained. The latencies of the electrical stimulation responses correlated well with the latencies in the EMGs obtained through sound stimulation. The evoked potentials after auditory and electrical stimulation were obtained in several nuclei in the brainstem. The conduction time between two nuclei was calculated by measuring the latency of discharges in each nucleus. The alteration of the evoked discharge was observed through surgical transection of the brainstem. After each successive surgery the EMG showed differences in responses. Thus, the location of the neural connections of the pathways were differentiated in the brainstem. From this, we concluded that the reflex arc has the following pathway: The acoustic input to the ventral cochlear nucleus (VCN) is relayed to the acoustic route of the superior olivary complex and to the lateral lemniscus. Then, the impulse reaches the VIIth nucleus via the pontine reticular formation in the ipsilateral side. On the other hand, the input to the VCN crosses over the trapezoid body to the superior olivary complex. Then, the impulse uses the same pathway as described for the contralateral side. Finally, the pathway of the acoustic blinking reflex is located more caudally than that of the tactual blinking reflex. The comparison of the recordings of both reflexes is useful clinically, as a diagnostic method to study the function of the brainstem.

Acoustic Stimulation↗
PubMedDate not supplied

[Blink reflex and jaw reflex in neurinoma of the acoustic and trigeminal nerves (author's transl)].

The blink reflex was studied in four patients with neurinoma of the acoustic nerve and in two patients with trigeminal neurinoma. It was abnormal in all cases except in one neurinoma of the acoustic nerve inside the canal. The jaw reflex, studied in four cases, showed unilateral impairment in two cases of trigeminal neurinoma and one case of acoustic neurinoma; it was normal in the case of acoustic neurinoma in the canal. The blink reflex and jaw reflex merit inclusion among the further tests conducted in cases of suspected neurinoma of the trigeminal or acoustic nerves. However, they are of less interest than oto-vestibular tets in the early diagnosis of neurinoma of the eighth nerve. These techniques deserve a place of choice in investigations of atypical facial neuralgia in general and suspected neurinoma of the trigeminal in particular.

Adult↗
PubMed1995

[Size of acoustic neurinomas assessed by CT and magnetic resonance scanning].

Some acoustic neuromas do not grow or grow very slowly. It is therefore of value to compare the results of measuring the size of acoustic neuromas by either CT or Magnetic Resonance Imaging (MRI) scanning with a view to being able to observe the growth rate of these tumours. Fifteen patients with acoustic neuromas had both CT- and MRI-scans performed. Two trained radiologists evaluated the size of the tumours in a blinded fashion. There was a significant difference between one observer's calculations from the CT- and the MRI-scans, and also a significant difference between the two observers' calculations from the CT-scans. No difference in calculating tumour size was found between the two observers' calculations from the MRI-scans. It is concluded that the size of acoustic neuromas i evaluated more equally by two observers using MRI-scans than when using CT-scans. By the use of repeated MRI-scanning it is possible to keep patients with acoustic nouromas under observation and avoid operation in those patients where the tumour does not grow.

Adult↗
PubMed1995

Acoustic neuroma surgery in patients over 65 years of age.

Patients over 65 years old develop acoustic neuromas with the same signs and symptoms as younger patients. Age limits beyond which surgery for acoustic neuroma is not offered have been suggested. Untreated vertigo in the older patient frequently results in a fall which causes a fracture of the femur followed by significant morbidity and mortality. A review of 62 cases done over a period of five years reveals that surgical removal of acoustic neuroma in eight patients over 65 years of age gave results equally good to those in younger patients. This study suggests that the patient's general medical condition, life expectancy and factors other than chronologic age should be considered in the indications for surgery of acoustic neuroma. Acoustic neuroma surgery for the older patient can provide gratifying results.

Adolescent↗
PubMed1994

Giant neurons in the rat reticular formation: a sensorimotor interface in the elementary acoustic startle circuit?

The mammalian acoustic startle response (ASR) is a relatively simple motor response that can be elicited by sudden and loud acoustic stimuli. The ASR shows several forms of plasticity, such as habituation, sensitization, and prepulse inhibition, thereby making it an interesting model for studying the underlying neuronal mechanisms. Among the neurons that compose the elementary startle circuit are giant neurons in the caudal pontine reticular nucleus (PnC), which may be good candidates for analyzing the neuronal basis of mammalian behavior. In a first step of this study, we employed retrograde and anterograde tracing techniques to identify the possible sources of input and the efferent targets of these neurons. In a second step, we performed intracellular recordings in vivo, followed by subsequent injections of HRP for morphological identification, thereby investigating whether characteristic features of the ASR are reflected by physiological properties of giant PnC neurons. Our observations demonstrate convergent, bilateral input from several auditory brainstem nuclei to the PnC, predominantly originating from neurons in the cochlear nuclear complex and the superior olivary complex. Almost no input neurons were found in the nuclei of the lateral lemniscus. As the relatively long neuronal response latencies in several of these auditory nuclei appear to be incompatible with the primary ASR, we conclude that neurons in the cochlear root nuclei most likely provide the auditory input to PnC neurons that is required to elicit the ASR. The giant PnC neurons have a remarkable number of physiological features supporting the hypothesis that they may be a neural correlate of the ASR: (1) they receive short-latency auditory input, (2) they have high firing thresholds and broad frequency tuning, (3) they are sensitive to changes in stimulus rise time and to paired-pulse stimulation, (4) repetitive acoustic stimulation results in habituation of their response, and (5) amygdaloid activity enhances their response to acoustic stimuli. Anterograde tracing showed that most giant PnC neurons are reticulospinal cells. Axon collaterals and terminal arbors were found in the reticular formation as well as in cranial and spinal motoneuron pools. The results of this study indicate that giant PnC neurons form a sensorimotor interface between the cochlear nuclear complex and cranial and spinal motoneurons. This neuronal pathway implies that the elementary acoustic startle circuit is composed of only three central relay stations and thus appears to be organized more simply than assumed in the past.

Acoustic Stimulation↗
PubMed1977

Acoustic microscopy of the human retina and pigment epithelium.

An acoustic microscope uses sound waves rather than light to image a sample, and displays viscoelastic rather than optical properties. The Stanford instrument, operating at frequencies near 1,000 MHz, achieves resolution and magnification that is comparable to a light microscope. Using this instrument, we examined sections of normal human retina and pigment epithelium and found that characteristic degrees of acoustic attenuation or phase shift were produced by structures such as cell nuclei, rod and cone outer segments, Bruch's membrane, red blood cells, and ocular pigment. Resolution was better with thin than thick sections, and fixation did not significantly alter the acoustic properties of the tissues studied. A comparison of iris tissue from albino and pigmented rabbits showed that melanin was a particularly strong acoustic attenuator. Acoustic microscopy may provide a new and direct means of probing the physical structure of tissues and cells.

Acoustics↗