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PubMed1985

[A case of acoustic neurinoma presenting as subarachnoid hemorrhage].

A case of acoustic neurinoma presenting with subarachnoid hemorrhage is reported. The patient, a 33-year-old female, had suffered from left hearing disturbance and tinnitus for several years prior to admission. She had sudden onset of severe headache in the left posterior auricular region, nausea and vomiting while watching a play-going. Immediately she was brought to a neighboring hospital by ambulance. Lumbar puncture demonstrated xanthochromic cerebrospinal fluid with high opening pressure of 380 mmH2O or more and she was diagnosed as having subarachnoid hemorrhage (SAH). As her level of consciousness was progressively lowered, she was transferred and admitted to our hospital. Findings of plain CT scan on admission suggested that she had a brainstem hemorrhage with acute obstructive hydrocephalus. After the immediate operation of ventricle drainage, she became alert. Two weeks after admission, contrast-enhanced CT scan, internal meatus tomography and vertebral angiography were performed because she complained of tinnitus and hearing loss of her left ear. A huge lt. C-P angle tumor was revealed and its total removal was carried out successfully after V-P shunt operation for her hydrocephalic condition. Histological examination showed a typical acoustic neurinoma. The postoperative course was uneventful only with a moderate facial paresis on her left side. Acute and severe subarachnoid hemorrhage of the posterior fossa in cases of acoustic neurinoma has been reported very sporadically. However, CT examination revealed such a rare case of acoustic neurinoma and lead us to a successful surgical treatment for the patient.

Adult↗
PubMed1984

High-resolution CT and air CT cisternography in the diagnosis of acoustic neuromas.

High-resolution thin-section computed tomography (CT) is helpful in determining the real extent of large acoustic neuromas by means of multiplanar reconstructions. High-resolution CT has to be performed early in the work-up of any patient suspected of acoustic neuroma. Small acoustic neuromas, however, can easily be overlooked because a high percentage of these tumors has an almost isodense appearance (54%), and because 53% enhances after intravenous contrast injection. High-resolution air CT cisternography has to be considered the method of choice for the detection or exclusion of small acoustic neuromas. This procedure also demonstrates ingrowth of the tumor into the neurovascular bundle.

Cerebellar Neoplasms↗
PubMed1983

Interaction of short latency cortical responses to somatosensory and acoustic stimuli in anterior part of middle suprasylvian gyrus of cat's brain.

The work sums up the results of experiments in which interaction was studied between cortical short latency nonprimary responses (SNPR) produced by paired stimuli in the anterior part of the middle suprasylvian gyrus of cat's brain. In paired stimuli (somatosensory + acoustic or acoustic + somatosensory) the second stimulus (test stimulus) followed after the first stimulus (conditioning stimulus) in intervals of 20 to 400 ms. An analysis of the results demonstrates that in an animal anaesthetized with Nembutal (35 mg/kg) an interaction takes place between central systems taking part in the origin of acoustic and somatosensory SNPR in the anterior part of middle suprasylvian gyrus. On the basis of these data the authors conclude that acoustic and somatosensory SNPR in the anterior part of middle suprasylvian gyrus result from the activity of two different and independent systems.

Acoustic Stimulation↗
PubMed1984

The properties of acoustically responsive cells in the anterior suprasylvian gyrus of the cat.

The properties of acoustically responsive neurons were studied in the anterior part of the suprasylvian gyrus ( ASG ) of cats anaesthetized with pentobarbital or chloralose-urethan. The acoustic responsiveness of the cells was screened with click stimuli. Whenever an acoustic response occurred, its properties were further analysed with the aid of spectrally pure tone pulses. The most important features of the responses given to pure tones of different frequencies were (a) short latency and (b) sharp tuning to well defined frequencies. In this respect the cells showed a close resemblance to those in the primary acoustic area (AI) and differed considerably from neurons of the middle suprasylvian association field (AMSA), which lacked well defined best frequency (BF) and responded with longer latencies. At the same time the ASG neurons showed responses to somatosensory stimuli thus representing a transition between neurons of primary sensory and association areas.

Acoustic Stimulation↗
PubMed1981

[Measurements of the acoustic reflex at variable static pressures (author's transl)].

Acoustic reflex measurements are made on thirty normal and three early stage otosclerotic ears at different static pressures in the ear canal and recorded as reflex-tympanogram at 200 Hz and 660 Hz probe-tone frequency. Acoustic reflexes were elicited contralaterally with a pure-tone stimulus at 2,000 Hz. This stimulus was chosen to avoid technical artifacts. An example of a normal acoustic reflex pattern as a function of variable static pressure is presented (Fig. 1). This record was made at 20 dB above the subjects reflex threshold, using 660 Hz probe-tone frequency. The reflex deflection of susceptance is positive up to pressures of plus or minus 50 mm H2O and then becomes negative. The reflex deflection of conductance is negative in the total range. A stiffened middle-ear system shows negative reflex deflection of both admittance components. The reflex-tympanograms (Fig. 2) show the admittance component curves as a function of variable static pressure with and without eliciting the acoustic reflex in case of a normal ear, using probe-tone frequencies of 220 Hz and 660 Hz at 10 dB and at 20 dB above the subjects reflex threshold. The reflex-tympanogram in case of an early stage otosclerotic ear shows negative reflex deflection of susceptance within the total pressure range indicating pathological stiffness (Fig. 3). The reflex related change of the dynamic properties was stimulated in a mathematical model of the middle-ear (Fig. 4). The measurements could be explained in a mathematical approach.

Audiometry↗
PubMed1981

[Early diagnosis of acoustic neuroma by the vestibular tests. Indication for computerized tomography and cisternomeatography (author's transl)].

In a series of 390 cases with suspicion of acoustic neurinomas 78 such tumors could be diagnosed, including 12 early stage neurinomas. This relatively high detection quote of small neurinomas is due to a special diagnostical programme: Every patient with unilateral and sensorineural hearing loss, independent of vertigo anamnesis or of the result of x-rays must be further examined by a vestibular tests. All 78 patients with acoustic neuroma had pathological vestibular findings. The positional test turned out to be the most sensitive examination in the early diagnosis of acoustic neuromas and yields a still higher incidence than the thermic test: 95% of the patients with a neuroma showed pathological findings in the positional test. Every patient suffering from an unidentified unilateral and sensorineural hearing loss combined with a pathological result in the positional tests must be further checked by a cisternomeatography or computerized tomography using airinsufflation. Every fifth of these patients showed typical signs of an acoustic neuroma in the neuroradiological tests. 68 neuromas are operated today and verified histologically, 10 patients are still waiting for surgical treatment.

Adolescent↗
PubMed1995

Magnetic resonance imaging of acoustic schwannomas.

The magnetic resonance imaging (MRI) findings of 27 histologically proven acoustic schwannomas in 24 patients (13 men, 11 women, age 20-79 yr) are described in detail. Three patients had bilateral tumors. Twenty-two tumors (82%) had intra- and extracanalicular components, three tumors (11%) were limited to the internal auditory canal (IAC) and two tumors (7%) were limited to the cerebellopontine angle (CPA). The diameters of extracanalicular lesions in the CPA ranged from 12 to 50 mm, and most of them were round in shape. All IAC portions of CPA tumors had a funnel-shaped appearance on the axial images and short-club-shaped configuration on the coronal images. There was strong homogeneous contrast enhancement of the solid components in 12 tumors (44%) and heterogeneous enhancement in 15 tumors (56%). The cystic components of the tumors correlated well with the histologic features. All tumors could be demonstrated in their enterity by MRI. The "short-club sign", first described in this study, helped to confirm the intracanalicular component of acoustic schwannomas, which were usually found in the cerebellar cistern. The results of this study show that MRI is a sensitive imaging modality for the assessment of acoustic schwannomas located at the CPA or IAC, or in both regions. MRI is non-invasive and does not involve ionizing radiation. It should be considered the imaging examination of choice to evaluate patients with suspected acoustic schwannomas.

Adult↗
PubMed1995

Functional outcome in patients after excision of extracanalicular acoustic neuromas using the suboccipital approach.

An audit of surgery for acoustic neuroma was carried out to determine the frequency and nature of postoperative symptoms and their impact upon the patient's quality of life and vocation. Fifty-six patients were interviewed between 6 months and 5 years (mean 26 months) after surgical excision of an acoustic neuroma. The objective surgical results in these patients are good, with normal or near normal functional preservation rates of 80% for the facial nerve (House-Brackmann grade I/II), and 27.3% for a previously functioning acoustic nerve. Despite this there was no significant overall reduction in the reported occurrence of balance problems, tinnitus, headache and other neurological sequelae of the tumour after surgical excision. In 20% of the patients persistent symptoms, including deafness and facial weakness, had prevented the resumption of former social activities. As a result of these symptoms 8.6% of the patients were certified medically unfit for work, but of those employed preoperatively over 70% had returned to their jobs. The success of neuro-otological surgical management of acoustic neuroma is offset by some degree of chronic morbidity. Our patients expressed the need to know whether their symptoms would resolve, but were often too afraid to ask. Patients can be reassured that the majority resume their former social and vocational activities, but should be advised that some symptoms can persist or occur de novo after surgery. Our data suggest that early intervention would reduce the incidence of these troublesome sequelae.

Adult↗
PubMed1994

Follow-up of patients with inverted papilloma of the nasal cavities: computer tomography, video-endoscopy, acoustic rhinometry?

Seventeen patients were operated suffering from unilateral inverted papilloma of the nasal cavities, in one male associated with malignancy. We investigated these patients pre- and post-operatively by clinical examination, video-endoscopy, acoustic rhinometry, and computed tomography (CT). The aim was to find out which technique delivers reliable information about tumour recurrence in follow-up. By these controls three recurrences could be detected in a period of two-years' follow-up. Our results showed that the combination of CT, video-endoscopy and histological examination of biopsies is reliable to detect recurrence of inverted papilloma. To study the possibilities of detecting tumour recurrence by means of acoustic rhinometry, investigations on models of nasal cavities with various shape, size and location of tumour masses were undertaken. A comparison between the results of the model study and the acoustic rhinometric measurements in patients showed that growth of tumour masses can be detected by this method in an early phase under constant conditions such as nasal models. In patients, however, it is not easy to evaluate the absolute size and site of the growing tumour masses, because there are several factors which lead to false-positive interpretations, such as localized inflammations of the mucosa, crusting and nasal secretion and especially the movements of the soft palate. We conclude from our results that acoustic rhinometry does not deliver more information than obtained by video-endoscopy and CT to detect tumour recurrence in the nasal cavity.

Acoustics↗
PubMed1993

Prognostic value of cardiotocographic acoustic test in post-term pregnancies.

The aim of the study was to evaluate the prognostic value of the acoustic test in post-term pregnancies. 80 acoustic tests were done (alkaline phosphatase and oxytocinase). In 12 cases, the cardiotocographic recordings of the acoustic test were described as incorrect, 11 neonates of this were born in asphyxia. In the group of neonates responding to the stimulus correctly, all neonates were born in a generally good state. The results show that the acoustic test is characterized by high prognostic value and a correct test result can predict a good fetal state.

Acoustic Stimulation↗
PubMed1994

Stability of hearing preservation following acoustic neuroma surgery.

Identification of small acoustic neuromas has become commonplace. Frequently, affected individuals are identified prior to the development of significant hearing loss. Whereas many studies have focused on hearing preservation surgery, few have reported on stability of hearing results after resection of acoustic neuroma. Between 1985 and 1991, 36 patients underwent resection of an acoustic neuroma via a retrosigmoid, internal auditory canal approach with attempted hearing preservation. Hearing was preserved in 24 patients; 17 were available for testing for the present study. Follow-up ranged from 1.5 to 8 years. All patients underwent complete audiologic assessment; most patients also underwent auditory brainstem response testing. There was an average 6 dB increase in pure-tone average between early (1 month) postoperative and long-term postoperative test results. A binomial single subject statistic was used to assess for significant changes in speech recognition scores over time. In two subjects there was a significant decrease; however, speech recognition also improved significantly in two subjects. Five of the 17 subjects demonstrated either a significant (at least 15 dB) increase in pure-tone average or a significant decrease in speech recognition over the time-course of the study. All patients maintained usable hearing. We conclude that long-term hearing preservation is a realistic goal in selected acoustic neuroma operations.

Audiometry, Pure-Tone↗
PubMed1993

Sleep stages and EEG power spectrum in relation to acoustical stimulus arousal threshold in the rat.

This study was designed to functionally validate earlier described criteria for visual sleep scoring with respect to acoustical stimulus threshold for arousal. A further objective was to explore the relation between electroencephalographic (EEG) power spectrum and acoustical stimulus threshold for arousal. After habituation to an acoustical stimulus (a 1,000-Hz sine tone, increasing 1.5 dB per second for 45 seconds), values for latency to arousal after acoustical stimulus onset were analyzed. Arousal was determined based on EEG and electromyographic (EMG) criteria. There was a significant effect of sleep stage, with slow wave sleep 2 (SWS-2) having higher arousal threshold than slow wave sleep 1 (SWS-1), rapid eye movement (REM) sleep and transition type sleep. This indicates that the subdivision of nonrapid eye movement (NREM) sleep in the rat into SWS-1 and SWS-2 had functional validity in this paradigm. Time of day also had a significant effect, with lower arousal threshold in the last 2 hours (ninth and tenth hour of the light period) of the 8-hour registration period. Furthermore, there was a significant effect of EEG delta power density. Epochs with high delta power had increased arousal threshold relative to epochs with low arousal threshold. The results were consistent with the notion that delta activity is an indicator of depth within NREM sleep.

Acoustic Stimulation↗
PubMed1994

Determinants and impact of headache after acoustic neuroma surgery.

Headache after acoustic neuroma surgery is known to occur clinically, but has not been studied systematically until recently. In the present study, 155 patients were surveyed regarding their experience of headache and associated symptoms following resection of an acoustic neuroma: 73 percent (n = 98) of patients undergoing suboccipital resection of an acoustic neuroma and 53 percent (n = 8) of patients undergoing translabyrinthine resection of acoustic neuroma complained of headache following surgery. The average pain intensity was greater for the suboccipital approach. Only 9 percent (n = 14) reported troublesome or frequent headaches preoperatively. Headache was described most often as tension type, with episodic acute exacerbations mimicking migraine. Clinical observations suggest that most patients are treated successfully with various combinations of reassurance, tricyclic antidepressants, nonsteroidal anti-inflammatory medications, trigger-point injections, adjunctive stress management techniques (relaxation), and physical therapy. The impact of recurrent headache on work and recreational function is notable. Several possible pathophysiological and biopsychosocial models are proposed to account for the prevalent headache problem. Although spontaneous resolution usually occurs over time, additional study is needed to determine the natural history of postoperative headache once it occurs.

Cranial Nerve Neoplasms↗
PubMed1995

Evaluation of residual acoustic schwannoma using gadolinium-DTPA enhanced magnetic resonance imaging with the fat suppression technique.

After subtotal resection of acoustic schwannomas, radiographic evaluation is necessary to evaluate tumor growth. With conventional gadolinium-DTPA T1-weighted magnetic resonance imaging, tumor delineation is often obscured by surgically placed fat. This occurs because fat has the same intensity as enhanced acoustic tumor. T1-weighted magnetic resonance fat suppression techniques can be used to eliminate the strong signal of fat tissue. When this technique is used in combination with gadolinium-DTPA, the definition of pathologic structures is improved in those areas containing large amounts of fat. Twelve patients who had subtotal resection of an acoustic schwannoma underwent gadolinium-DTPA enhanced magnetic resonance imaging using the fat suppression technique. Residual tumors were more conspicuous and had improved margin definition using the fat suppression technique compared to conventional gadolinium-DTPA T1-weighted images. These refinements in magnetic resonance imaging represent a significant advance in the assessment of residual acoustic tumors.

Adult↗
PubMed1996

Comparison of acoustic immittance measures obtained with different commercial instruments.

Three acoustic admittance measurements (tympanometric peak pressure, peak compensated static acoustic admittance, and tympanometric width) were compared across seven commercially available acoustic immittance systems. Forty-nine adult subjects (45 females and 4 males), 16 to 50 years of age (mean = 27.7 years), with normal middle ear function participated in this investigation. Small but statistically significant differences were observed for each of the tympanometric variables for several of the instruments evaluated. In most instances, the differences were small enough that the same normative data could be applied across the instrumentation employed in this study; however, there were two measurement conditions, peak compensated static acoustic admittance and tympanometric width, where, for selected instruments, the range in values differed by an amount great enough to warrant consideration in clinical decision making.

Acoustic Impedance Tests↗
PubMed1996

Delayed facial palsy after acoustic neuroma resection: the role of viral reactivation.

Delayed facial palsy after acoustic neuroma resection may occur in up to 15% of cases. Prognosis is generally good if the palsy does not progress to total paralysis. However, a delayed palsy with subsequent total paralysis has a more variable final outcome, which ranges from normal function to permanent total paralysis. This delayed paralysis has been attributed to edema from surgical manipulation of the facial nerve. Steroids and intraoperative decompression of the meatal foramen have been used with some success, but some cases remain refractory to these measures. Herpes simplex virus and varicella-zoster virus are ubiquitous in the population and remain in a latent state in neural ganglia. These viruses are reactivated during times of stress. Trigeminal nerve surgery (partial sensory rhizotomy and microvascular decompression) stimulates reactivation of herpes simplex with manifestations in the sensory distribution of the trigeminal nerve in 38-94% of procedures. Prevention of this reactivation has been demonstrated in placebo-controlled trials by using prophylactic acyclovir. We present a patient who underwent translabyrinthine resection of an intracanalicular acoustic neuroma and in whom developed otalgia, vesicles on the ear canal and the ipsilateral buccal mucosa, and progressive facial palsy the week after surgery. Serologic evaluation confirmed the diagnosis of herpes zoster oticus. Reactivation of latent virus apparently occurred as a result of surgical manipulation of the facial nerve. This parallels viral reactivation seen in trigeminal nerve surgery. We propose a new theory for an additional cause of delayed facial palsy after acoustic neuroma resection-reactivation of latent herpesvirus resulting from surgical trauma. Acyclovir should be evaluated in clinical trials for a prophylactic role in patients undergoing acoustic neuroma resection or a therapeutic role in patients in whom a delayed postoperative facial palsy develops.

Cranial Nerve Neoplasms↗
PubMed1996

Assessment of the allergic reaction in seasonal rhinitis: acoustic rhinometry is a sensitive and objective method.

BACKGROUND: Seasonal allergic rhinitis constitutes an excellent in vivo model of an allergic mucosal inflammatory reaction. This offers the opportunity of studying the fundamentals of allergic inflammation in addition to improvement of knowledge on the basal pathophysiological mechanisms of the disease. So far, monitoring methods of disease activity and treatment efficacy have mainly been based upon subjective assessments, illustrating the impact of introducing reliable objective methods. OBJECTIVE: To investigate the allergic inflammatory reaction of seasonal rhinitis through different objective methods and evaluate these as indicators of disease activity and treatment efficacy. METHODS: Functional parameters, i.e. acoustic rhinometry and nasal metacholine challenge, and biological markers, i.e. blood eosinophil count, eosinophil cationic protein in serum (s-ECP) and nasal lavage fluid (n-ECP), were assessed before and at peak pollen season in 27 patients with grass pollen induced rhinitis. Patients were randomized to either nasal corticosteroid or placebo treatment and recorded nasal symptom scores. RESULTS: Acoustic rhinometry revealed a significant difference in favour of steroid treatment (P < 0.05) comparing nasal volumes before and during season. This difference primarily relied upon a decrease in the placebo group (P = 0.05). A reduction from baseline of s-ECP in the steroid group (P < 0.01) was obtained. N-ECP demonstrated a difference between treatment groups, although not significant. Symptom scores increased in all patients during the pollen season, although this was only significant in the placebo treated patients (P < 0.01). The remaining methods applied did not demonstrate further differences, either within or between treatment groups. CONCLUSION: Our results demonstrate acoustic rhinometry to be a sensitive and objective method of assessment of nasal obstruction. Furthermore, acoustic rhinometry and s-ECP reflect the impact of nasal steroid therapy on seasonal allergic rhinitis.

Acoustics↗
PubMed1997

Management of acoustic neuroma in the elderly population.

OBJECTIVE: Ongoing controversy regarding the optimal treatment of acoustic neuromas in the elderly population has prompted us to examine the our experience in order to arrive at a treatment algorithm. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral center. PATIENTS: The records of 48 elderly patients ranging from age 70 to 90 years with acoustic tumors were reviewed. INTERVENTIONS: In 34 cases, tumor size was followed through serial imaging for a mean 28.5 months (range 5-108 months). Eight of these patients subsequently required surgery for significant tumor growth. An additional 12 patients were managed surgically from the time of diagnosis. MAIN OUTCOME MEASURE: The natural history of acoustic neuromas in the elderly population. RESULTS: The mean tumor growth rate for the watched group was 0.29 cm/y. Fifteen patients demonstrated no growth whereas accelerated growth was noted in eight cases. Ten patients with tumors confined to the internal auditory canal demonstrated an average growth rate of only 0.06 cm/y over a mean interval of 38 months. For the surgically treated group, the mean tumor size at the time of resection was 2.8 cm. Resection was described as complete in 17 cases and near-total in three cases. Perioperative complication rates and facial nerve results were comparable to our figures for all age groups. There was one perioperative death. CONCLUSIONS: Elderly patients with small acoustic neuromas should be offered a trial of observation. When significant tumor growth, size, or neurologic deterioration are demonstrated, early surgical intervention is required to avoid complications associated with the removal of larger tumors.

Abdomen↗