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PubMed1991

Operative management of acoustic neuromas: the priority of neurologic function over complete resection.

The objective of surgical management of acoustic tumors is to remove them entirely and preserve facial nerve function and hearing when possible. A dilemma arises when it is not possible to remove the entire tumor without incurring additional neurologic deficits. Twenty patients who underwent intentional incomplete surgical removal of an acoustic neuroma to avoid further neurologic deficit were retrospectively reviewed. They were divided into a subtotal group (resection of less than 95% of tumor) and a near-total group (resection of 95% or more of tumor) and were followed yearly with either computed tomography or magnetic resonance imaging. The subtotal group was planned and consisted of elderly patients (mean age, 68.5 years) with large tumors (mean, 3.1 cm). The near-total group consisted of younger patients (mean age, 45.8 years) and smaller tumors (mean, 2.3 cm). The mean length of followup for all patients was 5.0 years. Ninety percent of patients had House grade I or II facial function post-operatively. Radiologically detectable tumor regrowth occurred in only one patient, who was in the subtotal resection group. Near-total resection of acoustic tumor was not associated with radiologic evidence of regrowth of tumor for the period of observation. Within the limits of the follow-up period of this study, subtotal resection of acoustic neuroma in elderly patients was not associated with clinically significant recurrence in most patients and produced highly satisfactory rates of facial preservation with low surgical morbidity.

Adult↗
PubMed2005

Diazepam suppresses the acquisition but not the expression of 'fear-potentiation' of the acoustic startle response in man.

Sudden auditory stimuli elicit a short-latency muscular response (acoustic startle response) which is enhanced during presentation of a Pavlovian conditioned stimulus (CS) that has previously been paired with an aversive unconditioned stimulus (US) ('fear-potentiation'). In rodents, acute treatment with benzodiazepines blocks both the acquisition of fear-potentiation and the expression of fear-potentiation induced by prior exposure to CS/US pairing. We examined the effect of diazepam on the acquisition and expression of fear-potentiation of the acoustic startle response in man. Forty-six male volunteers (18-30 years) participated in two sessions separated by 7 days. In session 1, they were exposed to 20 2-s presentations of a light (CS), 50% of which terminated with an electric shock to the wrist (1.8 mA, 50 ms: US). Somatosensory potentials evoked by the US were recorded from the scalp at Cz, and skin conductance responses from electrodes taped to the second and fourth fingers. In session 2, the CS was presented 20 times without the US; a random 50% of CS presentations terminated with a sound pulse (40-ms 115-dB 1-kHz); an equal number of sound pulses was presented without the CS. Electromyographic responses of the orbicularis oculi muscle to the acoustic stimuli were recorded from electrodes placed on the lower eyelid, late-latency auditory evoked potentials were recorded at Cz, and skin conductance responses from electrodes taped to the second and fourth fingers. In each session, alertness was measured using visual analogue self-rating scales and critical flicker fusion frequency. Subjects received placebo or diazepam 10mg in the two sessions in a double-blind protocol: group 1 (n 12) placebo/placebo; group 2 (n 11) placebo/diazepam; group 3 (n 12) diazepam/placebo; group 4 (n 11) diazepam/diazepam. Diazepam reduced alertness as measured by visual-analogue self-rating scales and critical flicker fusion frequency. In session 1, diazepam reduced the amplitude of the somatosensory potentials and skin conductance responses evoked by the CS. In session 2, the acoustic startle response, the N1/P2 auditory evoked response and the skin conductance response evoked by the sound stimuli were enhanced in the presence of the CS. This fear-potentiation was attenuated in subjects who received diazepam in session 1, but was not affected by the treatment given in session 2. The results indicate that diazepam blocks the acquisition of fear-potentiation of startle responses in man, as in animals, but does not prevent the expression of a previously learned response.

Acoustic Stimulation↗
PubMed1982

Neuroradiological detection of small and intracanalicular acoustic tumors: an emphasis on CO2 contrast-enhanced computed tomographic cisternography.

Seventy patients suspected clinically of having an acoustic tumor were evaluated using the computed tomographic (CT) scan as the initial neuroradiological procedure, followed by CO2 contrast CT cisternography in cases where the intravenous contrast-enhanced scan did not reveal any lesion. Forty-eight gas CT cisternograms revealed 10 small acoustic tumors, 2 of which were totally intracanalicular. The authors present a review of the basic CT anatomy of the temporal bone as it relates to acoustic tumors. Based upon the ease of performance of the procedure, the low postexamination morbidity, and the excellent diagnostic results, CO2 CT cisternography is recommended as the procedure of choice in the diagnosis of small and intracanalicular acoustic tumors.

Adult↗
PubMed1995

Outcome analysis of acoustic neuroma management: a comparison of microsurgery and stereotactic radiosurgery.

Currently, microsurgical resection of acoustic neuromas by an experienced, multidisciplinary team is thought to be the treatment of choice. During the past 20 years stereotactic radiosurgery has been used as an alternative to surgical removal. To compare the results of both microsurgery and stereotactic radiosurgery, we conducted a study of 87 patients with unilateral, previously unoperated acoustic neuromas with an average diameter less than 3 cm treated by the neurosurgical service during 1990 and 1991. Preoperative patient characteristics and average tumor size were similar between the treatment groups. State of the art microsurgical or radiosurgical techniques were used by experienced surgeons in both treatment groups. The treatment groups were compared based on cranial nerve preservation, tumor control, postoperative complications, patient symptomatology, length of hospital stay, total management charges, effect on employment status, and overall patient satisfaction. Stereotactic radiosurgery was more effective in preserving normal postoperative facial function (P < 0.05), and hearing preservation (P < 0.03) with less treatment associated morbidity (P < 0.01). Effect on preoperative symptoms were similar between the treatment groups. Postoperative functional outcomes and patients' satisfaction of their tumor management were greater after stereotactic radiosurgery when compared to the microsurgical group, although they did not reach statistical significance (P = 0.07 and P = 0.10, respectively). Patients returned to independent functioning sooner after stereotactic radiosurgery (P < 0.001). Hospital length of stay and total management charges were less in the radiosurgical group (P < 0.001). When compared to microsurgical removal, stereotactic radiosurgery proved to be an effective and less costly management strategy of unilateral acoustic neuromas less than 3 cm in diameter. For many acoustic neuroma patients, stereotactic radiosurgery should be offered as an alternative management strategy.

Adult↗
PubMed2003

One-stage removal of residual intracanalicular acoustic neuroma and hemihypoglossal-intratemporal facial nerve anastomosis: technical note.

OBJECTIVE AND IMPORTANCE: Incomplete removal of residual intracanalicular tumor and injury to the facial nerve are the main problems associated with surgery of large acoustic neuromas via the retromastoid suboccipital approach. In patients with residual or recurrent intracanalicular neuromas, the translabyrinthine approach is the preferred surgical route, allowing complete tumor removal; it may eventually also be used for exposure of the intratemporal portion of the facial nerve for a hemihypoglossal-facial nerve anastomosis when a postoperative facial palsy exists This one-stage procedure has not been described previously. CLINICAL PRESENTATION: Three patients with postoperative facial palsy and residual intracanalicular tumor after surgical removal of a large acoustic neuroma via the retromastoid suboccipital approach underwent reoperation via the translabyrinthine approach and one-stage removal of the residual tumor and hemihypoglossal-facial nerve anastomosis. All three patients had a complete facial palsy of House-Brackmann Grade VI and a residual tumor of 8 to 12 mm. TECHNIQUE: A classic translabyrinthine approach was used to open the internal auditory canal and remove the residual intracanalicular tumor. The facial nerve was exposed in its mastoid and tympanic parts, mobilized, and transected; then, the long nerve stump was transposed into the neck and used for an end-to-side anastomosis into the hypoglossal nerve. The operation resulted in variable improvement of the facial muscle function up to Grade III (one patient) and Grade IV (two patients). CONCLUSION: Reoperation via the translabyrinthine approach is indicated for removal of residual intracanalicular acoustic neuroma and realization of a hypoglossal-facial nerve anastomosis in a single procedure. It is suggested that this type of anastomosis may also be used during the initial operation for acoustic neuroma removal when the facial nerve is inadvertently sectioned.

Anastomosis, Surgical↗
PubMed2001

The acoustic advantage of hunting at low heights above water: behavioural experiments on the European 'trawling' bats Myotis capaccinii, M. dasycneme and M. daubentonii.

We have demonstrated in behavioural experiments that success in capturing prey from surfaces in 'trawling Myotis' (Leuconoë-type) depends on the acoustic properties of the surface on which the prey is presented. Two types of surface structure were ensonified with artificial bat signals to probe their acoustic characteristics. We have shown that perception of prey by echolocation is easier if the prey is presented on a smooth surface (such as calm water) than if it is presented on a structured surface (such as vegetation or the ground). This is because the smooth surface reflects a much lower level of clutter echoes than the structured one if ensonified at an angle typical for bats foraging low over water. The ensonification experiments revealed that the sound pressure level of the echo was even higher for mealworms on a smooth surface than for mealworms suspended in air. This might be because waves travelling via the surface also contribute to the echo (e.g. reflection from the surface to the mealworm, back to the surface and then to the receiver). From the behavioural experiments, we conclude that 'trawling Myotis' take isolated objects on smooth (water) surfaces for prey. Those objects reflect isolated, stationary acoustic glints back to the echolocating bats. Conversely, 'trawling Myotis' will not recognise prey if prey echoes are embedded in numerous clutter echoes. We have demonstrated marked similarities between the three European 'trawling Myotis' species M. dasycneme, M. daubentonii and M. capaccinii in echolocation behaviour, search image, foraging strategy and prey perception. We propose that a combination of prey abundance and acoustic advantages could have led to repeated and convergent evolution of 'trawling' bats in different parts of the world.

Acoustics↗
PubMed1991

The response to acoustic stimulation and the changes in brain amine levels after repeated administration of beta-phenylethylamine in rats.

Reverse tolerance to stereotyped behavior was induced after repeated administration of beta-phenylethylamine (PEA) (50 mg/kg, i.p., daily for 10 days) in rats. The reverse tolerance was maintained for at least 4 weeks after the last administration. We studied the effects of acoustic stimulation on locomotor activity 2 days and 4 weeks after withdrawal from PEA and measured the changes in brain monoamine levels 4 weeks after the withdrawal. Locomotor activity during acoustic stimulation was increased in the saline treated group, and this response was unaffected after repeated PEA treatment. Four weeks after withdrawal, significant increases in noradrenaline levels in the cerebral cortex and decreases in 5-hydroxytryptamine levels in the hypothalamus were found. The effects of acoustic stimulation on locomotor activity and the changes in brain monoamine levels were different from those of methamphetamine treatment obtained in our previous study. In conclusion, it may be suggested that the response to acoustic stimulation after repeated PEA administration in rats cannot be a model for abnormal responsiveness to environmental stimulation that is observed in chronic paranoid schizophrenics.

Acoustic Stimulation↗
PubMed2005

The influence of the Internet on decision making in acoustic neuroma.

OBJECTIVE: To determine the access to and the use of the Internet by acoustic neuroma patients as a medical information source, and the influence of the Internet on decision-making, as well as the patients' views on the quality of particular sites. MATERIALS AND METHODS: A retrospective 27-item questionnaire was sent to 138 consecutive acoustic neuroma patients diagnosed between 1997 and 2002. The study included patients treated by conservative, radiotherapeutic and surgical modalities. MAIN OUTCOME MEASURES: Patient demographics, the extent of Internet use as well as quality and quantity of available information. RESULTS: There were 86.95 per cent questionnaires available for analysis. Twenty-four per cent accessed the Internet to obtain information about acoustic neuromas. Ninety-seven per cent of patients said that the information provided in the clinic matched with the information obtained from the websites, 49 per cent said that the information obtained from the Internet did not influence decision making regarding acceptance of treatment of their tumour. Some patients said the Internet information was depressing, devastating, and they would never look up the Internet again for medical information. CONCLUSION: A significant proportion of our patients accessed the Internet for information. Caution should be exercised when advising patients regarding websites as the information on the Internet is often not controlled or checked for accuracy. Acoustic neuroma specialists and ENT surgeons in general should familiarize themselves with related websites so that patients can then be directed to high-quality sites.

Attitude to Health↗
PubMed1975

Recent advances in acoustical microscopy.

One cannot be involved in research in universities, government establishments and industry for 35 years without becoming aware of a number of misconceptions about pure science, applied science, engineering and technology in the mind of the public and also in the very places where research is carried out. There is confusion about the aims of research and development. There is uncertainty about the proper roles of universities, research establishments and industry. There is the question whether science is intrinsically good or not. The author illuminates some of these issues by relating milestones in the development of microscopy--optical as well as electron--and gives a snapshot picture of the recent work at Stanford University on the acoustic microscope as a felicitous instance of physics applied to the ever-present desire of mankind: to explore the unknown and to understand nature. Experiments with a mechanically scanning type of acoustic microscope have shown that a resolution limited only by diffraction can be attained and using a sonic frequency of 1-2 GHz, objects of less than 1 mum diameter can in principle be resolved. Various biological tissues have been explored and it appears that the acoustical images contain information substantially different from that obtained optically or electron-optically. Images have also been obtained using the harmonic radiation generated within the object and this mode of operation promises to open up yet another dimension of information. When, in due course, the full power, and the limitations, of the acoustic microscope are appreciated, its use may well lead to advances in science and technology comparable to those brought about by the introduction of the electron microscope.

Acoustics↗
PubMed1988

Magnetic resonance imaging of acoustic neuromas: the role of gadolinium-DTPA.

Magnetic resonance imaging (MRI) was performed in 20 patients with evidence on computed tomography (CT) of 21 acoustic neuromas before and after intravenous administration (0.1-0.2 mmol/kg body weight) of gadolinium-diethylene-triamine-pentaacetic acid (Gd-DTPA). Multi-section spin-echo (SE) sequences of varying repetition (TR) and echo (TE) times were performed in the transverse and coronal planes with a section thickness of 10 mm. All acoustic neuromas displayed marked enhancement on the T1-weighted (short TR/TE) SE sequence post-Gd-DTPA. The intrameatal component was particularly well demonstrated compared with non-enhanced magnetic resonance (MR) images and contrast-enhanced CT. Identification of intrameatal tumour was difficult on T2-weighted SE images and one tumour was not identified on the T1-weighted SE sequence prior to Gd-DTPA. Four of five intrameatal tumours measuring less than 8 mm could only be demonstrated on CT by using CT air meatography. Extrameatal tumour extension was demonstrated on contrast-enhanced CT, although the assessment of brain-stem involvement and displacement was not as clearly seen as on coronal MR images. In two patients with large acoustic neuromas and a cyst, the true relationship of the cyst to the tumour could only be identified on the post-Gd-DTPA scan. Magnetic resonance imaging with gadolinium-DTPA is a relatively quick, safe, well tolerated and effective method for the diagnosis of acoustic neuroma.

Adolescent↗
PubMed1989

Acoustic neuroma--the patient's perspective: subjective assessment of symptoms, diagnosis, therapy, and outcome in 541 patients.

Surgical treatment of acoustic neuroma has been reviewed in the medical literature, but assessment of outcome from the patient's perspective has received little attention. The Acoustic Neuroma Association (A.N.A.) is a large organization of acoustic neuroma patients which provides information and support services. This article reports the subjective assessment of symptoms, diagnosis, treatment, and outcome as evaluated by 541 A.N.A. members. This retrospective study presents an extensive overview of the experience of acoustic neuroma patients treated at a variety of institutions, and provides a unique perspective not previously represented in the medical literature.

Adult↗
PubMed1991

Turbinate hypertrophy in habitual snorers and patients with obstructive sleep apnea: findings of acoustic rhinometry.

Forty-five habitual snorers (mean respiratory disturbance index = 6) and 22 patients with obstructive sleep apnea syndrome (mean respiratory disturbance index = 36) were examined by polysomnography, radiocephalometry, rhinomanometry, nasopharyngeal videoendoscopy, and acoustic rhinometry. In 97% of these patients, hypertrophy of the inferior nasal turbinates was found by acoustic rhinometry, while increased nasal resistance of various degrees was measured in 93% of all patients by active anterior rhinomanometry. Acoustic rhinometry demonstrated that the most resistive segment was located in the anterior parts of the nasal cavity and was built up by two compartments: the region of the isthmus nasi and the region of the head of the inferior turbinate. In our snoring patients, the cross-sectional areas at the head of the inferior turbinate were always smaller than the cross-sectional areas in the isthmus nasi, which in normal controls presented the minimal cross-sectional values of the whole nasal cavity. While rhino-manometry can only measure the amount of nasal resistance, acoustic rhinometry can clearly determine the exact size and location of the different stenoses in the nasal cavity that contribute to the increased nasal resistance.

Acoustics↗
PubMed1993

Treatment of an acoustic neuroma in an only-hearing ear: case reports and considerations for the future.

Current options regarding the treatment of acoustic neuroma in an only-hearing ear include: observation, attempted hearing preservation surgery, and stereotactically guided radiation therapy. A patient who had a left labyrinthectomy for Menière's disease presented 15 years later with a large right acoustic neuroma. Due to anticipated profound deafness, he fit the criteria for cochlear implantation. Promontory stimulation of the left ear was positive. He underwent successful left cochlear implantation with the Nucleus 22-channel device and was successfully rehabilitated. He then underwent translabyrinthine removal of his right-sided 2.5-cm acoustic neuroma. This case is used to illustrate a new option available to those faced with treating a patient with acoustic neuroma in an only-hearing ear. How this approach may fit in with other available options will be discussed.

Cochlear Implants↗
PubMed1994

Nasal cavity area in term infants determined by acoustic rhinometry.

The present study was undertaken to determine whether a modification to commercially available acoustic rhinometry (AR) instrumentation might allow equipment designed for use in adults to determine accurately the nasal cavity configuration of infants and children. The standard wave tube was replaced with a version having a narrow (0.312-cm2) internal diameter (ID). Before use with neonates, the accuracy of this instrument was evaluated using the nasal cavity of a full-term infant cadaver. Acoustic nasal area curves were compared to area measurements of polyvinylsiloxane nasal casts and direct volume measurements of the specimen. AR correlated well with nasal cast data (r = .88) for total nasal cavity area. The acoustic method underestimated the total area at the nasal valve by only 1.8 mm2 (22.1 mm2 vs. 23.9 mm2) and overestimated choanal area by 10 mm2 (56.9 mm2 vs. 46.9 mm2). In addition, AR measured total nasal volume to within 5.2% of the value obtained by direct measurement. In a cohort of 10 normal, term infants, the mean acoustic value for total nasal valve area was 19.2 +/- 0.05 mm2 and for total nasal volume was 1.76 +/- 0.53 cm3. This, the first report of nasal area and volume information in live infants, suggests that the modified AR device has utility both in airway research and as a nasal patency screening tool in the pediatric population.

Acoustics↗
PubMed1995

Acoustic schwannoma and pregnancy: a DNA flow cytometric, steroid hormone receptor, and proliferation marker study.

For a long time, it has been speculated that pregnancy stimulates the growth of acoustic schwannomas. To test this hypothesis, immunohistochemical stains for estrogen receptor, progesterone receptor, and proliferating cell nuclear antigen (PCNA) were performed. Flow cytometric studies for DNA ploidy and S-phase fraction determinations were also performed. The study subjects included 6 female patients with unilateral acoustic tumors; at the time of tumor removal, 1 woman was pregnant and the other 5 women were 2 to 10 months postpartum. The age-sex-matched control group consisted of 6 men and 12 nonpregnant women, all with acoustic schwannomas similar in size to those of the study group. The study found no statistically significant association between the presence or quantity of estrogen or progesterone receptors and pregnancy, DNA ploidy, proliferation indices, or clinical data. Based on PCNA indices, large tumors tended to be less "biologically active" than small lesions (P < .01). The authors concluded that pregnancy does not significantly stimulate the cellular growth of acoustic schwannomas.

Biomarkers↗
PubMed1995

Unilateral acoustic tumors: how often do they recur after translabyrinthine removal?

Unilateral acoustic tumors rarely recur after total translabyrinthine removal. Review of the patient records of the House Ear Clinic revealed five recurrent tumors, for an approximate incidence of 0.3%. A questionnaire was mailed to 857 patients who were at least 9 years postoperative and failed to find any additional recurrent tumors. No preoperative or intraoperative factors were identified to predict recurrence. The average time interval from initial removal to recurrence was approximately 10 years. Flow cytometric analysis did not reveal any fundamental differences between the recurrent acoustic tumor group and a larger group of 112 acoustic tumors. Based on observed growth rates of the recurrent acoustic tumors, a single gadolinium-enhanced magnetic resonance image 5 years after surgery is advised. To prevent recurrence, a margin of normal-appearing proximal eighth cranial nerve should be removed and the nerve stump cauterized.

Adult↗
PubMed2001

Inhaled beclomethasone dipropionate improves acoustic measures of voice in patients with asthma.

BACKGROUND: Inhaled corticosteroids have the potential to produce upper-airway side effects such as hoarseness. As new compounds and delivery devices are developed and compared, it is difficult to quantify their adverse upper-airway effects. OBJECTIVE: We undertook the following study to test the ability of an acoustic analysis technique to quantify changes in vocal function in steroid-naive patients with asthma who receive inhaled beclomethasone dipropionate (BDP), 1,000 microg/d for 4 months. METHODS: Patients self-administered one of four regimens of inhaled BDP. Group 1 patients received one 250-microg puff qid via metered-dose inhaler (MDI); group 2 patients received one 250-microg puff qid via MDI with a holding chamber; group 3 patients received two 250-microg puffs bid via MDI; and group 4 patients received two 250-microg puffs bid via MDI with a holding chamber. A smaller cohort of nonsmoking asthmatic patients was managed without steroid intervention for 4 months. At baseline and again at 8 weeks and 16 weeks after the initiation of BDP treatment, patients underwent spirometry and methacholine challenge. At baseline and again at 2, 4, 8, 12, and 16 weeks, patients underwent voice recording for analysis of voice parameters. The recorded vowels were low-pass filtered (10 KHz), digitized (22 KHz), and analyzed by software to obtain two acoustic measures: (1) jitter, the cycle-to-cycle variation in the time period of the voice signal; and (2) shimmer, the cycle-to-cycle variation in voice signal amplitude. RESULTS: We recruited 77 patients for randomization to inhaled steroid therapy and 10 patients who continued to receive only occasional inhaled bronchodilator therapy. In all active treatment groups, FEV(1), FVC, and provocative concentration of methacholine causing a 20% fall in FEV(1) improved significantly after BDP treatment. Mean jitter scores, a measurement of variation in voice pitch, were not significantly influenced by BDP treatment. However, mean shimmer scores, a reflection of perturbation in vocal amplitude, fell significantly (p < 0.05) in the active treatment groups. These reductions in shimmer scores were not significantly different in the active treatment groups. Shimmer scores in the bronchodilator-treated group were unchanged during the 16 weeks of follow-up. CONCLUSIONS: Our data show that a simple and noninvasive acoustic analysis of voice is sensitive to subclinical changes associated with inhaled corticosteroid therapy. We have shown that 1,000 microg/d of inhaled BDP actually improves specific acoustic measures of voice in patients with inadequately controlled asthma. These improvements were uninfluenced by dosing schedule and whether a spacing chamber was used.

Administration, Inhalation↗
PubMed1992

Vibro-acoustic stimulation in high-risk pregnancies; maternal perception of fetal movements, fetal heart rate and fetal outcome.

Maternal perception of fetal movement in response to vibro-acoustic stimulation was compared with antenatal fetal heart rate monitoring as a test of fetal well-being in a population of gravidae with high-risk pregnancies (n = 517), admitted to the high-risk ward at Danderyd Hospital, Karolinska Institutet; a total of 2,015 tests were performed. The sensitivity and the specificity of the test compared to the fetal heart rate tracing was 81% and 89% respectively. If the test was performed within 24 hours of delivery, its predictive value for fetal asphyxia (i.e. a 5-minute Apgar score < 7) was 14% (7/49). Ten per cent of the patients felt no fetal movement in response to stimulation (irrespective of gestational age). In five cases where fetal heart rate tracings were pathological, stimulation nonetheless produced fetal movement and fetal outcome was good. Pathological heart rate tracings and no fetal movement in response to stimulation were present in 30 cases (out of 251 with no fetal movements at stimulation), in seven of which the infants had 5-minute Apgar scores < 7. Although many patients underwent repeated vibro-acoustic stimulation, there was no evidence of fetal habituation to the test. On 24 occasions (i.e. 1.2%), the patient denied vibro-acoustic stimulation, mostly because of previous discomfort due to vigorous fetal response. Where resources are limited, maternal perception of fetal movements in response to vibro-acoustic stimulation might be a useful alternative for preliminary screening of high-risk pregnancies.

Acoustic Stimulation↗