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In 1989, the Acoustic Neuroma Association established a multisurgeon, multi-institutional registry to collect data related to the treatment of patients with acoustic neuroma. This report analyzes information from the 1579 surgically treated patients who were entered in the registry between January 1, 1989, and February 28, 1994.
OBJECTIVES: On the basis of survey results of the Acoustic Neuroma Association (ANA), we report patient ratings of postoperative headache (POH) symptoms, determine its effect on quality of life (QOL), and review the literature regarding POH after acoustic neuroma (AN) treatment. STUDY DESIGN: In this cohort study, 1,657 patients who underwent surgical treatment of AN reported their experiences of POH. METHODS: A detailed questionnaire was mailed to members of the ANA to identify preoperative and postoperative headache symptoms, complications, and long-term effects on physical and psychosocial function. Questions were answered by 1657 (85.4%) respondents that were intended to qualify and quantify the effects of POH, including QOL issues. Responses were analyzed by tumor size, surgical approach, and patient age and sex. Statistical analysis was performed with the SPSS software. RESULTS: Preoperative headache was reported in approximately one third of respondents. Typical POHs occurred more than once daily (46%), lasted 1 to 4 hours in duration (43.1%), and were of moderate intensity (62.6%). The worst headaches were rated as "severe" by 77% of respondents. Treatment most often reported for typical headaches were nonprescription medications including nonsteroidal anti-inflammatory drugs in 61.3% (P < .01) and regular use of narcotics in 15%. Patients who underwent the retrosigmoid approach were significantly more likely to report their worst POH as "severe" (82.3%) compared with the translabyrinthine (75.2%) and middle fossa approaches (63.3%). Women and younger patients tended to have poorer outcomes with regard to POHs. CONCLUSIONS: In this large cohort study of AN patients, POH was a significant morbidity among AN patients with persistent headaches. Treating physicians should be aware of the risk factors identified and the effect POH has on the QOL when counseling patients regarding optimal treatment management.
The study by Brenkman et al. [J. Acoust. Soc. Am. 82, 1646-1654 (1987)] of malleus umbo and anterior crus of stapes displacement in 14 human temporal bones shows a mean -7.3-dB/oct slope above 1.0 kHz for stapes displacement in response to a 80-dB SPL input at the eardrum. The slope they obtained for midfrequency (1.0-4.0 kHz) stapes displacement is significantly flatter than what was found previously [Gyo et al., Acta Otolaryngol. 103, 87-95 (1987); Gundersen, Prostheses in the Ossicular Chain (University Park, Baltimore, MD, 1971); Kringlebotn and Gundersen, J. Acoust. Soc. Am. 77, 159-164 (1985); Vlaming and Feenstra, Clin. Otolaryngol. 11, 353-363 (1986a)]; in these studies, stapes displacement rolled off at -12.0 to -14.9 dB/oct above 1.0 kHz. It appears that their mean midfrequency stapes displacement slope has been flattened by some unusual results in a small number of ears. Possible reasons for these results are discussed.
In this work acoustic microcavitation in water is studied primarily at 0.75 MHz and 1% duty cycle. To detect cavitation, two kinds of acoustic detectors are used. The first one is an unfocused, untuned 1-MHz receiver transducer that serves as a passive detector. The other one is a focused 30-MHz transducer that is used in pulse-echo mode and is called the active detector. Cavitation itself is brought about by a focused PZT-8 crystal driven in pulse mode. The active detector is arranged confocally with respect to the cavitation transducer. Both the interrogating pulse and the cavitation pulse arrive simultaneously at the common focus, which is the region of cavitation. With the test chamber filled with clean water, no cavitation is observed, even when the cavitation transducer is driven to give its peak output of 22 bar peak negative. Cavitation is, however, observed when polystyrene microparticles are added to the host water. Our view of how these smooth, spherical, monodispersed microparticles give rise to cavitation is described with some estimates. An attempt has been made to understand whether the presence of "streaming" affects the thresholds, and it has been found that the active detector field affects the cavitation process.
The feasibility of using evoked oto-acoustic emission (EOAE) measurement for intra-operative monitoring of cochlear function was assessed during removal of an acoustic neuroma in a 53-year-old woman with normal hearing on the operated side prior to surgery. The high level of noise in the operating theatre was the only material problem encountered and this was not sufficient to prevent recording of identifiable waveforms. During manipulation of the brainstem, damage to the cochlea was indicated by an increase in EOAE latency and its eventual disappearance. A total hearing loss in the operated ear was revealed after surgery. Monitoring cochlear function with EOAEs is probably best considered at present as an adjunct to auditory brainstem response monitoring of the composite cochlea and eighth nerve, thus providing differential information.
The results are presented from a consecutive operative series of 62 acoustic neuromas in 60 patients following the introduction of improved neurophysiological monitoring techniques. Twenty-two patients had usable preoperative hearing. Thirty tumours were less than 2.5 cm diameter and 32 greater in size. Operation was via a 3-4-cm diameter retromastoid craniectomy. The internal auditory meatus was opened by an ENT surgeon (RM) using a drill and the facial nerve identified by stimulation. The tumour was then centrally evacuated by a neurosurgeon (MT/HC) using an ultrasonic aspirator, and the thin exterior part of the tumour carefully dissected off the nerves in or around the capsule with constant stimulation and monitoring of facial EMG, BSAEP and electrocochleography. A new type of stimulation probe has been designed and coupled to a stimulator/integrator/tone burst generator (SB) so that continuous immediate direct feedback to the surgeon is possible. A variable amplitude discriminator rejects baseline EMG (> 50 microV) and a gating circuit prevents stimulus artefact (during monopolar stimulation) from causing interference. By these means the VII nerve could be identified even when translucent and undefinable as a nerve bundle. Anatomical preservation was possible in 98% of VII nerves. Full facial function was present in 20 cases immediately postoperatively. Full delayed recovery occurred in 23 cases giving an eventual total in House Grade I of 69%. Seven other cases recovered to House Grade II. There was therefore 81% satisfactory facial nerve function. This percentage is exactly the same for larger and for smaller tumours. Anatomical preservation of the VIII nerve was achieved in 24/62 (39%) of the whole series and 11/16 (69%) of those with a hearing loss of < 50 dB. Functional preservation of hearing described as usable by the patient (< 65 dB) was achieved in 7/22 cases (32%), 3/13 (23%) in tumours < 2.5 cm and 4/9 (44%) in those > 2.5 cm diameter. Hearing preservation of < 50 dB in patients with preoperative hearing threshold < 50 dB and tumours of < 2.5 cm was 3/11 (27%). Monitoring by BSAEP and ECochG was technically unsatisfactory because the responses were affected by drilling and stimulation. Acoustic nerve preservation should be attempted in all cases with measurable hearing, regardless of tumour size.
Acoustic rhinometry (AR) is a technique of nasal patency assessment, ever more frequently used in clinical practice. As yet, no generally accepted recommendations has been developed concerning the method of examination performing. In the paper the technique of examination is presented and the recommendations of the Committee for Standardisation of Acoustic Rhinometry, European Rhinologic Association are discussed.
The aim of this article is to carry out a critical analysis of the clinical applications of acoustic oto-emissions based on analysis of more than 1,000 adult and pediatric audiometric records. The principal technical and clinical properties of acoustic oto-emissions are described. The clinical value would seem to be very limited in adult audiology, whereas this examination would appear to be a reliable and non invasive method for screening in children at risk of cochlear deafness. In this respect, the investigation is principally limited by middle ear pathology and involvement of the central auditory pathways.
Time characteristics of brain stem acoustic evoked potentials and acoustic reflex of the intra-aural muscles were measured in workers with occupational hypoacusis having normal and delayed capacity for speech discrimination. The findings provided evidence for inhibition of speech information analysis at the level of the brain stem and dissociation of interaction between the brain stem nuclei.
Acoustic and other tumors of the cerebellopontine angle are not uncommon, and they usually have otologic symptoms or findings. Early diagnosis depends on a high index of suspicion and a thorough evaluation of patients with suspected tumors. This is a report of 24 cases selected from a group of 184 surgically confirmed tumors. Had the cases been evaluated only on the basis of pure tone or speech audiometry or on the basis of plain roentgenograms, the diagnosis might not have been made. Audiological examination should include the acoustic reflex test. The results of this test indicated a retrocochlear problem (absence or decay of the reflex) in 19 of 24 cases (80%). The test was positive in 11 of 12 patients with normal or near normal hearing and in seven of eight patients with normal x-ray films.
Acoustical and histological properties of dog kidney parenchyma are examined in vitro to determine sources of acoustic scattering in the normal kidney. The speed of sound, attenuation, backscatter, effective scatterer size and scattering strength were measured within the frequency range 1-15 MHz and at eight angles of incidence with respect to the predominant nephron orientation. Significant angular dependence, or anisotropy, was observed in backscatter coefficient and scattering strength estimates; attenuation was found to be weakly anisotropic. All three parameters, each measured at 19 degrees C, exhibited values that were maximum for perpendicular incidence and minimum for parallel incidence. Speed of sound and scatterer size estimates were observed to be independent of scanning angle. Comparisons between these data for renal cortex and histological observations suggest that the glomerulus is the principal scatterer at low frequencies, and renal tubules and blood vessels at high frequencies.
This paper describes the application of a novel broadband acoustic sensor to evaluating the acoustic emissions from cavitation produced by a typical commercial 20 kHz sonochemical horn processor. Investigations of the reproducibility of the processor, and of the variation in cavitation emissions as a function of output setting and sensor location are described, and resulting trends discussed in terms of the broadband integrated power in the megahertz frequency range. Companion studies with a conventional membrane hydrophone have illustrated for the first time that cavitation emissions produced by a sonochemical horn processor can extend to frequencies beyond 20 MHz, and the sensor shows that significant nonlinearity can be seen in measured cavitation activity with increasing nominal output power.
A large, flat ultrasonic transmitter and a small receiver are developed for studies of material properties in acoustic transmission goniometry. While the character of the wave field produced by the transmitter can be considered as a plane wave as observed by the receiver, diffraction effects are noticeable near critical angles and result in the appearance of weak but detectable arrivals. Transmitted ultrasonic waveforms are acquired in one elastic silicate glass and two visco-elastic acrylic glass sample plates as a function of the angle of incidence. Phase velocities are determined from modeling of the shape of curves of the observed arrival times versus angle of incidence. The waveform observations are modeled using a phase propagation technique that incorporates full wave behavior including attenuation. Subtle diffraction effects are captured in addition to the main bounded pulse propagation. The full propagation modeling allows for various arrivals to be unambiguously interpreted. The results of the plane wave solution are close to the full wave propagation modeling without any corrections to the observed wave field. This is an advantage as it places confidence that later analyses can use simpler plane wave solutions without the need for additional diffraction corrections. A further advantage is that the uniform bounded acoustic pulse allows for the detection of weak arrivals such as a low energy edge diffraction observed in our experiments.
The authors respond to Fitch's comments [H. Fitch, J. Acoust. Soc. Am. 86, 2017-2019 (1989)] on an earlier paper. New analyses are presented to address the question of whether F1 differences observed in the original report are an artifact of linear predictive coding (LPC) analysis techniques. Contrary to Fitch's claims, the results suggest that the F1 differences originally reported are, in fact, due to changes in vocal tract resonance characteristics. It is concluded that there are important acoustic-phonetic differences in speech when talkers speak in noise. These differences reflect changes in both glottal and supraglottal events that are designed to maintain speech intelligibility under adverse conditions.
The vibroacoustic behavior of an elastic, simply supported rectangular plate covered by a locally reacting decoupling layer supporting thickness deformation is presented. The model simulates the vibration and acoustic response of the system immersed in water and subjected to a point force disturbance. A simplified version of the theory is derived in the limiting case of a large decoupling (low mechanical impedance of the layer/high frequency). An appropriate vibratory indicator, representative of the acoustic attenuation provided by the decoupling treatment, and independent of the structure dimensions, is also investigated from the perspective of small-scale laboratory characterization.
The extent of hearing fatigue as a consequence of acoustic impacts is an important factor in predicting an anticipated hearing impairment. It is essential to know whether hearing fatigue is due to physiological or pathological conditions. Mass screenings of thousands of soldiers suffering from hearing fatigue due to acoustic impact, showed that hearing fatigue is subject to considerable individual fluctuation. The time of recovery, or rather the time required by the auditory reception to return to the preimpact threshold, is of paramount importance. Recovery from an audiometrically traceable TTS within 10 minutes can be considered unobjectionable. Recovery time of up to half an hour can be found in 10--20% of the screened personnel, depending on the impact. This is within physiological variation range and can be considered unobjectionable. Recovery times of a TTS of up to 3 hours constitute a limit beyond which pathological effects in the cochlea can be expected. Recovery times of 24 hours and more signify a definite impairment if impacts continue.
Spontaneous, tone-like emissions produced by normal ears and measured in the closed outer ear canal can be affected by mechanical and acoustical events. Such effects can be measured in steady-state conditions as well as for transient stimulation, and are seen in response to the stapedius reflex, to ear canal air pressure changes, and to the presentation of external tones. Frequency and level of the emissions follow certain characteristics which are described and discussed. The emissions seem to react with 2 ms delay and with an exponential rise and decay, the time constant of which is about 13 ms.
We studied the middle and inner ears of seven adult coruros (Spalacopus cyanus), subterranean and social rodents from central Chile, using free-hand dissection and routine staining techniques. Middle ear parameters that were focused on here (enlarged bullae and eardrums, ossicles of the "freely mobile type") are believed to enhance hearing sensitivity at lower frequencies. The organ of Corti was of a common mammalian type and revealed three peaks of higher inner hair cell densities. Based on a position frequency map, frequencies were assigned to the respective peaks along the basilar membrane. The first peak at around 300-400 Hz is discussed with respect to the burrow acoustics, while the peak around 10-20 kHz is probably a plesiomorphic feature. The most pronounced peak at around 2 kHz reflects the frequency at which the main energy of vocal communication occurs. The morphology of the ear of the coruro corresponds to the typical pattern seen in subterranean rodents (low frequency and low-sensitivity hearers), yet, at the same time, it also deviates from it in several functionally relevant features.