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At least 649 records · Page 36Linked to original sources
PubMed1997

Preoperative and postoperative nasal septal surgery assessment with acoustic rhinometry.

INTRODUCTION: Acoustic rhinometry is a relatively new tool used for the measurement of the geometry of the nasal fossa. We hypothesized that acoustic rhinometry would be useful for preoperative and postoperative assessment of patients undergoing septal surgery. METHODS AND MATERIAL: Twenty-four patients undergoing septal surgery performed by two surgeons underwent preoperative and postoperative rhinometry. The indications for surgery were nasal obstruction caused by a deviated nasal septum. Rhinometry was conducted with the Eccovision Acoustic Rhinometry System (Hood Laboratories). Analysis of the data was performed with the Kwikstat program (Texasoft) and Excel (Microsoft). RESULTS: Subjective improvement in nasal patency was significantly correlated with improvement in acoustic rhinometry. CONCLUSIONS: Acoustic rhinometry is valuable in objectively confirming nasal patency after nasal septal and turbinate surgery.

Acoustics↗
PubMed1989

Acoustic otoscopy in the diagnosis of otitis media.

Acoustic otoscopy detects middle ear pathology by measuring the ability of the tympanic membrane to reflect sound. Fluid or thickening of the tympanic membrane increases sound reflection. We conducted a study to compare acoustic otoscopy with pneumatic otoscopy in identifying middle ear pathology in 80 children (160 ears) presenting to the emergency department with ear or upper respiratory complaints. We then evaluated the use of acoustic otoscopy in 34 adults (68 ears) with and without ear complaints. Using a reflectivity of 5 or more units to signify acute pathology in children, the sensitivity was 82%, and the specificity was 100%. Using a reflectivity of 6 or more units to indicate acute suppurative pathology in adults, the sensitivity was 83%, and the specificity was 95%. We found acoustic otoscopy to be objective, practical, and reproducible. We conclude that acoustic otoscopy is a valuable adjunct in the diagnosis of otitis media in children and adults.

Acoustic Stimulation↗
PubMedDate not supplied

The acoustic reflex in patients with asymptomatic multiple sclerosis.

A convenient, inexpensive test to identify multiple sclerosis during periods of symptomatic remission would be clinically advantageous. Recent studies have suggested that examination of acoustic reflex onset latency and rise time may be useful in detecting some forms of retrocochlear auditory pathology. This prospective, single-blinded study compares these features of the human acoustic reflex in a control sample, a sample with sensorineural hearing loss, and a sample with multiple sclerosis, to determine the usefulness of acoustic reflex measurements as a screening test for otherwise asymptomatic multiple sclerosis. Acoustic reflex threshold, onset latency, and rise time measurements were similar for all groups. This finding suggests that tests for abnormalities of acoustic reflex rise time and onset latency, under the conditions used in this study, may not be sufficiently sensitive to screen for the presence of otherwise asymptomatic multiple sclerosis.

Adult↗
PubMed2002

Nonlinear acoustics in diagnostic ultrasound.

The propagation of ultrasonic waves is nonlinear. Phenomena associated with the propagation of diagnostic ultrasound pulses cannot be predicted using linear assumptions alone. These include a progressive distortion in waveform, the generation of frequency harmonics and acoustic shocks, excess deposition of energy and acoustic saturation. These effects occur most strongly when ultrasound propagates within liquids with comparatively low acoustic attenuation, such as water, amniotic fluid or urine. Within soft tissues, similar effects occur, although they are limited by absorption and scattering. Nonlinear effects are of considerable importance during acoustic measurements, especially when these are used to predict in situ exposure. Harmonic generation may be used to create images. These offer improvements over conventional B-mode images in spatial resolution and, more significantly, in the suppression of acoustic clutter and side-lobe artifacts. B/A has promise as a parameter for tissue characterisation, but methods for imaging B/A have shown limited success.

Acoustics↗
PubMed2000

Calculation of cranial nerve complication probability for acoustic neuroma radiosurgery.

PURPOSE: Estimations of complications from stereotactic radiosurgery usually rely simply on dose-volume or dose-diameter isoeffect curves. Due to the sparse clinical data available, these curves have typically not considered the target location in the brain, target histology, or treatment plan conformality as parameters in the calculation. In this study, a predictive model was generated to estimate the probability of cranial neuropathies as a result of acoustic schwannoma radiosurgery. METHODS AND MATERIALS: The dose-volume histogram reduction scheme was used to calculate the normal tissue complication probability (NTCP) from brainstem dose-volume histograms. The model's fitting parameters were optimized to provide the best fit to the observed complication data for acoustic neuroma patients treated with stereotactic radiosurgery at the University of Florida. The calculation was then applied to the remainder of the patients in the database. RESULTS: The best fit to our clinical data was obtained using n = 0.04, m = 0.15, and alpha/beta = 2.1 Gy(-1). Although the fitting parameter m is relatively consistent with ranges found in the literature, both the volume parameter, n, and alpha/beta are much smaller than the values quoted in the literature. The fit to our clinical data indicates that brainstem, or possibly a specific portion of the brainstem, is more radiosensitive than the parameters in the literature indicate, and that there is very little volume effect; in other words, irradiation of a small fraction of the brainstem yields NTCPs that are nearly as high as those calculated for entire volume irradiation. These new fitting parameters are specific to acoustic neuroma radiosurgery, and the small volume effect that we observe may be an artifact of the fixed relationship of acoustic tumors to specific regions of the brainstem. Applying the model to our patient database, we calculate an average NTCP of 7.2% for patients who had no cranial nerve complications, and the average NTCP for was 66% for patients who sustained a cranial neuropathy. For the entire patient population, the actual percentage of patients suffering either facial or trigeminal neuropathy was 14.7%, whereas the calculated average NTCP was 14.8%. DISCUSSION: NTCP calculations using brainstem dose-volume histograms can be used to estimate the rate of cranial neuropathies from acoustic neuroma radiosurgery. More clinical data and further study will lead to refinement of the model with time.

Brain Stem↗
PubMed2001

Inner ear lesion alters acoustically induced c-Fos expression in the rat auditory rhomboencephalic brainstem.

The pattern of c-Fos expression was mapped in the adult rat's brain following unilateral cochlear lesions. In normal and cochlear lesioned rats, c-Fos expression was induced with sound stimuli. Acoustic stimulation consisted of pulses of four tones. An additional control group consisted of non-stimulated rats. In the cochlear nuclei (CN), c-Fos activation was scarce in isolated rats and increased strongly following sound stimulation. Following unilateral cochlear lesion, acoustically driven expression was decreased in all CN in both the lesioned and the untreated sides. The ventromedial periolivary nucleus and the rostral periolivary nucleus showed c-Fos activation in isolated conditions and were strongly activated following sound stimulation. The rest of the superior olivary complex showed no c-Fos activation in isolated rats and a weak activation following sound stimulation. Following unilateral cochlear lesions, acoustically driven expression was decreased in some, but not all superior olivary nuclei in both the lesioned and the untreated sides. In the lateral lemniscus complex, c-Fos activation was scarce in isolated rats and increased strongly after stimulation. Following unilateral cochlear lesion, acoustically driven expression decreased bilaterally in all nuclei. We have found that unilateral inner ear lesions lead to bilateral impairment of the capability of acoustic pathway neurons, to being c-Fos-activated following sound stimulation.

Acoustic Stimulation↗
PubMed1999

Acoustically and electrically evoked contralateral suppression of otoacoustic emissions in guinea pigs.

It is generally accepted that stimulation of the efferent auditory system results in changes of cochlear activity. A simple method of activating the olivocochlear pathway by contralateral electrical stimulation of the round window (ES-RW) was used in this study with the aim of comparing the efficacy of acoustically and/or electrically evoked contralateral suppression. The suppression of transient evoked otoacoustic emissions (TEOAEs) and distortion product otoacoustic emissions (DPOAEs) was elicited by contralateral acoustic stimulation (AS) (61 dB SPL continuous white noise), and/or by electrical stimulation of an electrode implanted at the contralateral round window (monopolar rectangular pulses 0.1 ms, repetition rate 300 Hz, intensity 50-100 PA) in 12 guinea pigs. The average value of contralateral suppression of TEOAEs amounted to 1.04 +/- 0.48 dB for acoustic stimulation and 0.97 +/- 0.53 dB for round window electrical stimulation. The simultaneous presentation of both acoustic and electrical stimulation had only a slight additive effect and resulted in 1.27 +/- 0.79 dB diminution of TEOAEs. The suppression of DPOAEs during contralateral acoustic and electrical stimulation was evident mainly at low and middle frequencies (14 kHz). In two guinea pigs the maximum DPOAE suppression was present at high frequencies. The average values of contralateral suppression measured at individual f2 frequencies of DPOAEs were similar to those calculated from 1/4 octave power spectrum analysis of the TEOAEs in half of the animals. The results demonstrated that contralateral ES-RW had a similar suppressive effect on TEOAEs and DPOAEs as did contralateral AS and simultaneous AS+(ES-RW). The results of spectral analysis suggested that both modes of contralateral stimulation excited similar sensory cochlear elements and induce comparable suppression of both TEOAEs and DPOAEs.

Acoustic Stimulation↗
PubMed1991

Early diagnosis of acoustic neuroma (1989) after experience of 37 cases.

Although the diagnosis of acoustic neuroma as classically described is generally thought to be easy, this is not always true for this so-called "ear tumor" which is localized within the internal auditory meatus. Recently, remarkable progress has been made in the diagnostic instrumentation and operative techniques used to treat acoustic neuroma, emphasizing the need for early diagnosis so that treatment can take place earlier than before. Through early diagnosis, some cases of total resection of acoustic neuroma have recently become possible, with preservation of not only facial nerve function, but preservation of auditory function as well. In the present report, we outline the early diagnosis of acoustic neuroma by summarizing 37 cases of acoustic neuroma experienced at our institution. We discuss historical presentations, and laboratory tests used in diagnosis including pure tone audiometry, speech audiometry, auditory brainstem evoked response (ABR), vestibular caloric stimulation, and computed tomography (CT) enhanced by introduction of air into the posterior fossa. Two representative cases are also presented. It should be emphasized that no clinical test is 100% sensitive or specific, and attention must be paid to chronological discrepancies in the patient's presentation and "cookbook"-type approaches to evaluation should be avoided.

Adult↗
PubMed1988

Clinico-statistical study on acoustic tumors with sudden hearing loss.

Acoustic tumors associated with sudden hearing loss were studied clinico-statistically to clarify the differential diagnosis between so-called sudden deafness and acoustic tumor of this type. A significant difference was found in the frequency of such abnormalities as gaze nystagmus, canal paresis in the caloric (nystagmus) test, inhibition of optokinetic nystagmus, dilatation of the internal auditory canal, and cranial nerve signs. However, there was no significant difference in such symptoms as preceding upper respiratory tract infection and rotatory vertigo at the onset of sudden deafness. In this study, most of the patients with sudden deafness had tumors of 2 cm or larger in diameter. Apart from the atypical feature of sudden onset, the acoustic tumors of this type have several characteristics. Therefore, the differential diagnosis of two diseases is not difficult if the possibility of acoustic tumor is taken into consideration and the above tests are performed for equivocal cases. The CT scan provides the most useful information for making a definite diagnosis of acoustic tumors in cases of this type.

Audiometry, Pure-Tone↗
PubMed1997

MR imaging of acoustic neuroma with high resolution fast spin echo T2-weighted sequence.

OBJECTIVE: To assess the value of high resolution 2D fast spin echo T2-weighted sequence (HR 2D-FSE T2w) for evaluating the internal auditory meatus (IAM) in patients with asymetric or unilateral sensorineural hearing loss, vs. gadolinium-enhanced T1-weighted (T1w) sequence; to suggest a screening protocol to exclude the diagnosis of acoustic neuroma in a patient with isolated unilateral sensorineural hearing loss. MATERIALS AND METHODS: One-hundred ten patients with suspected acoustic neuroma were evaluated with 1.5 T MRI system. The protocol included axial images focused on the IAM: HR 2D-FSE T2w images (4000/63, ETL = 16, 3-mm sections with 1.5 mm overlap, 18 FOV, 512 x 384 matrix) and gadolinium-enhanced T1w images (600/23, 3-mm sections, 18 FOV, 256 x 192 matrix). Two criteria for normality of the HR 2D-FSE T2w examination are defined: high homogeneous signal of the cerebellospinal fluid (CSF) and linear low signal of the nerves visible throughout the IAM. RESULTS: Overall results show no false-negative and six false-positive with HR 2D-FSE T2w sequences vs. gadolinium-enhanced T1w sequences. The sensitivity of HR 2D-FSE T2w sequences is 100%, specificity 93%, and negative preditive value 100%: normal images using HR 2D-FSE T2w sequence can rule out the diagnosis of acoustic neuroma. CONCLUSION: Using this protocol we can exclude the diagnosis of acoustic neuroma in case of normal HR 2D-FSE images and no additional gadolinium-enhanced T1w sequence is necessary. This protocol might reduce examination time, must promote recourse to MRI in the event of clinical suspicion of acoustic neuroma, and also enables savings by proposing MRI examination as a first-line exam.

Adult↗
PubMedDate not supplied

Effects of chronic low-level oral lead exposure on prepulse inhibition of acoustic startle in the rat.

Previous work has suggested that the behavioral effects of chronic low-level lead exposure on fixed interval (FI) operant behavior result from enhanced dopaminergic neurotransmission in the nucleus accumbens (Cory-Slechta et al., J Pharmacol Exp Ther 286: 794-805, 1998). The present studies were designed to further characterize the effects of chronic low-level oral lead exposure on another behavior that is modulated by dopaminergic neurotransmission in the nucleus accumbens. In these studies acoustic startle and the prepulse inhibition (PPI) of startle were studied in rats following chronic low-level oral lead exposure. Weanling male rats were treated for 5-6 weeks with lead via drinking water (250 ppm lead acetate; controls drank 250 ppm sodium acetate). Acoustic startle reactivity (95, 105, and 115 dB noise bursts) and PPI (prepulses of 1-8 dB over the 70-dB background) of startle were tested following lead exposure. Lead exposure did not affect body weight. Lead exposure also did not significantly affect baseline [i.e., no prepulse inhibition (NO-PPI)] acoustic startle as measured by 1) startle amplitude on the first startle trial (105 dB), 2) the average startle amplitude for the first ten trials (105 dB), or 3) the average startle amplitude for the NO-PPI trials during PPI testing (95, 105, and 115 dB). Lead exposure also did not affect the latency to onset for the startle response. In contrast, for both the 105 dB and 115 dB acoustic startle stimuli, chronic low-level oral lead exposure significantly attenuated the capacity of an acoustic prepulse to reduce the startle response. This effect was present whether the data were presented and analyzed as raw change from baseline or as the percentage of baseline startle. Given the strong link between the modulation of PPI and dopaminergic neurotransmission in the nucleus accumbens, the present data support the hypothesis that chronic low-level oral lead exposure facilitates dopamine neurotransmission in the nucleus accumbens.

Acoustic Stimulation↗
PubMed2000

Adductor spasmodic dysphonia and muscular tension dysphonia: acoustic analysis of sustained phonation and reading.

Acoustic phonatory events were identified in 10 women diagnosed with adductor spasmodic dysphonia (ADSD) and compared to 5 women and 5 men diagnosed with muscle tension dysphonia (MTD). The three acoustic parameters examined during sustained vowel production and reading included phonatory breaks, aperiodicity, and frequency shifts. Intra- and intermeasurer correlations showed high reliability for the measures. Findings indicated that those with ADSD produced a greater number of aberrant acoustic events than those with MTD. The results suggested that: (1) only those with ADSD show evidence of phonatory breaks during vocalization, albeit a sustained vowel or voicing during reading; (2) those with ADSD demonstrate greater variation in the type of aberrant acoustic events produced as a function of speech task. The latter point suggests that control of the larynx varies as a function of task demand, a finding not evident in the functionally based disorder of MTD. MTD is a disorder that often presents itself in a similar clinical manner to ADSD because of its perceptual commonalties and resembling laryngoscopic characteristics. The acoustic analysis presented in this study could be used as a method to assist in distinguishing between the two disorder types.

Acoustics↗
PubMed2002

Acoustical aspects of vocal function following radiotherapy for early T1a laryngeal cancer.

We evaluated acoustic voice characteristics of 18 male patients undergoing radiotherapy. The subjects were seen for voice assessment preradiotherapy and at 1 month, 3 months, 6 months, and 1 year following radiotherapy. A multidimensional voice analysis computer program (IVANS, Avaaz Innovations, 1998) was employed to evaluate measures of traditional frequency and amplitude perturbation as well as time-based and linear prediction (LP) modeled "noise" parameters of the acoustic output in conjunction with perceptual judgments of overall vocal quality. The results indicate vocal deterioration of vocal function immediately following radiotherapy with gradual and significant improvement in acoustic and perceptual features over 9 to 12 months following the radiation treatment. Measures of glottal noise demonstrated higher sensitivity than frequency-based measures of voice perturbation, and with more consistent, less variable changes in acoustical voice output from the preradiation to the 12 month postradiation periods. Future research evaluating vowel type and acoustic perturbation measures with a larger sample of subjects over a longer time period seems warranted.

Adult↗
PubMed2002

Acoustic analyses of developmental changes and emotional expression in the preverbal vocalizations of infants.

The nonverbal vocal utterances of seven normally hearing infants were studied within their first year of life with respect to age- and emotion-related changes. Supported by a multiparametric acoustic analysis it was possible to distinguish one inspiratory and eleven expiratory call types. Most of the call types appeared within the first two months; some emerged in the majority of infants not until the 5th ("laugh") or 7th month ("babble"). Age-related changes in acoustic structure were found in only 4 call types ("discomfort cry," "short discomfort cry," "wail," "moan"). The acoustic changes were characterized mainly by an increase in harmonic-to-noise ratio and homogeneity of the call, a decrease in frequency range and a downward shift of acoustic energy from higher to lower frequencies. Emotion-related differences were found in the acoustic structure of single call types as well as in the frequency of occurrence of different call types. A change from positive to negative emotional state was accompanied by an increase in call duration, frequency range, and peak frequency (frequency with the highest amplitude within the power spectrum). Negative emotions, in addition, were characterized by a significantly higher rate of "crying," "hic" and "ingressive vocalizations" than positive emotions, while positive emotions showed a significantly higher rate of "babble," "laugh," and "raspberry."

Affect↗
PubMed1998

Physical and mechanical properties of ePTFE stretch vascular grafts determined by time-resolved scanning acoustic microscopy.

OBJECTIVES: Determination of physical and mechanical characteristics and properties of thin-walled (0.39 mm) expanded polytetrafluoroethylene stretch vascular prostheses by time-resolved scanning acoustic microscopy (TR-SAM). MATERIALS AND METHODS: Samples of Stretch Gore-Tex were mounted on polymethylmethaacrylate substrate, and ethyl alcohol was used as acoustic couplant. A 10 MHz ultrasound transducer mounted on a SAM50 scanning acoustic microscope generated short, pulsed sound waves. Reflected signals were used for imaging and for computer analysis of time resolved wave forms acquired by a digital sampling oscilloscope to calculate physical and mechanical characteristics of the material. RESULTS: Graft wall thickness: 0.395 (0.352/0.401) mm; graft wall sound wave penetration velocity: 1111 (1083/1129) ms-1; acoustic impedance: 3.685 (2.975/4.370) 10(6) kg m-3s-1; attenuation coefficient: 0.144 (0.096/0.229) dB mm-1 MHz-1; material density: 3360 (2712/3982) kg m-3; elastic stiffness: 4.06 (3.35/4.83) GPa (median and (25/75) percentiles; n = 8 samples, 10 measurements spaced 100 microns apart in each sample). CONCLUSIONS: TR-SAM can effectively quantify ePTFE graft wall properties, and new data on graft properties have been provided. The acoustic impedance and elastic stiffness of the ePTFE graft wall are 2.2 and 1.6 times higher, respectively, than in human coronary arteries, and it is highly reflective of ultrasound.

Acoustics↗
PubMed2002

[High jugular bulb and its relationship with acoustic neurinoma surgery].

The jugular bulb is formed by the junction of the sigmoid sinus, inferior petrous sinus and the jugular vein. It is housed in the jugular fossa of the petrous pyramid. Variations in its size, location and relationship to the internal acoustic canal (IAC) have been reported. When the jugular bulb is located medial and less than 2 mm from the posterior wall of the internal acoustic canal, it is named as high jugular bulb. If the surgeon is not aware of this variation, damage to this structure can result in profuse haemorrhage and air embolism. This anatomical change also makes difficult the access to the intracanalicular portion of acoustic neurinomas when these tumours are excised by a retrosigmoid approach. We present the case of a patient with an acoustic schwannoma in whom a preoperative axial cranial CT revealed a high jugular bulb. To control this venous structure, we opened the IAC in a longitudinal manner achieving a total excision of the lesion preserving the function of the facial nerve. We conclude that preoperative radiological investigations in acoustic schwannomas surgery should include cranial MR and TC, to rule out the presence of a high jugular bulb. Cranial axial CT including bony windows and slices of 1.5 mm thick, should be carried out to exclude a high jugular bulb.

Brain↗
PubMed1985

Acoustic neuromas: management of 204 cases.

This paper reviews the author's personal experience with the management of 204 patients with the clinical diagnosis of acoustic neuroma. Craniotomy was performed in 181 of these cases, all of whom were proven to have acoustic neuromas. The remaining 23 cases with the clinical diagnosis of acoustic neuroma did not have tumour surgery, mainly because of advanced age or concurrent disease, although some required shunts for hydrocephalus. The management of acoustic neuromas including the selection of surgical approach depends upon the patient's age and general health, the size and growth direction of the tumour, previous surgical attempts at removal, and the presence of hydrocephalus, a contralateral tumour, and serviceable hearing. Twenty-nine other cases with the clinical diagnosis of acoustic neuroma underwent craniotomy: 20 had petrous or tentorial meningiomas encroaching on the porus acousticus or growing in the internal auditory canal, six had neuromas of the seventh cranial nerve and three had arachnoiditis occluding the internal auditory canal.

Cranial Nerve Neoplasms↗
PubMedDate not supplied

Loss of genes on chromosome 22 in tumorigenesis of human acoustic neuroma.

The application of recombinant DNA techniques has identified two fundamental mechanisms of tumorigenesis in man. The first involves a qualitative or quantitative change in an oncogene (see ref. 1 for review). In the second, discovered in embryonal tumours, a primary mutation occurs which is recessive at the cellular level to the normal allele. The growth of a tumour ensues only after a secondary change, such as chromosome loss or mitotic recombination, eliminates the normal allele, thereby unmasking the altered allele. Because its effect is recessive, the primary mutation may also occur and be transmitted in the germ line, resulting in a familial pattern for the disease. In familial cases, independent bilateral tumours are common, since the tumours result from a single event--loss of the normal genes--which can occur in any cell. This contrasts with non-familial (sporadic) cases where solitary tumours result from the infrequent occurrence of two rare events within the same cell. By a molecular genetic approach we have now shown that acoustic neuroma, one of the most common tumours of the human nervous system, is specifically associated with loss of genes on human chromosome 22 and may result from the mechanism of tumorigenesis discovered in embryonal tumours. This finding might provide a clue to the chromosomal location of the defective gene in bilateral acoustic neurofibromatosis, an autosomal dominant disorder with the hallmark of bilateral acoustic neuromas. In view of the frequent occurrence of meningiomas in patients with bilateral acoustic neurofibromatosis and the association of meningioma with loss of chromosome 22 previously reported in cytogenetic studies, we suggest that a common event underlies tumorigenesis in acoustic neuroma and meningioma.

Chromosome Deletion↗