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11/46. cerebellopontine angle lipomatous hamartoma of nerve: case report.

    cerebellopontine angle lipoma has been previously described in 21 patients and is frequently unresectable. An intracanalicular lipomatous hamartoma in a 60-year-old male is presented. MRI enabled a correct preoperative diagnosis to be made. Complete surgical excision, without major neurologic deficit was achieved. A review of the literature reveals that the tumor is frequently infiltrative, especially when vascular elements are prominent. The histologic characteristics and the hamartomatous nature of the lesion are discussed. ( info)

12/46. lightning and its effects on the auditory system.

    patients struck by lightning can present with a wide variety of unusual otologic problems including burns to the external auditory canal, tympanic membrane rupture, middle ear injury, and sensorineural hearing loss. Four patients who incurred various otologic problems, including one patient with previously unreported bilateral oval window fistulas following lightning injury, are presented. Audiologic, otologic, and surgical findings are reviewed as well as patient follow-up and outcome. ( info)

13/46. Progressive hereditary deafness with predominant inner hair cell loss.

    This paper presents the first case of human genetic hearing loss due to predominant inner hair cell damage investigated by psychoacoustic audiometry, auditory brainstem responses (ABR), evoked acoustic emissions (EAEs), and distortion product otoacoustic emissions (DPOEs). The genetic transmission was an autosomal dominant inheritance. The audiogram pattern was a dominant high-frequency hearing loss. EAE and DPOE properties were normal. Bronx waltzer mutant mouse with genetically determined predominant inner hair cell defects provide an interesting model to study this congenital deafness. This rare congenital deafness with predominant damage to inner hair cells cannot be detected by neonatal screening techniques using EAEs or DPOEs. ( info)

14/46. High-frequency electrostimulation hearing after mastoidectomy.

    This study was undertaken to measure the degree of high-frequency sensorineural hearing loss following mastoid surgery. Twenty-five patients undergoing mastoidectomy procedures were tested preoperatively, less than 2 days postoperatively, and at 30 days postoperatively using the Tonndorf Audimax 500 high-frequency audiometer. Electrostimulation thresholds in 1-kHz intervals, from 1 to 20 kHz, were measured, and the highest detectable frequency was determined to within 0.1 kHz. Surgical drilling time was recorded. Average drilling time was 51 minutes. A significant temporary threshold shift was observed, measurable at multiple frequencies, less than 48 hours after mastoidectomy. There was no clinically significant change in electrostimulation thresholds (measured in 1-kHz increments, from 1 to 16 kHz) preoperatively to 30 days postoperatively. A statistically significant average loss of 0.89 kHz in the highest frequency producing a measurable response was noted (p less than 0.05). Determinations of the highest measurable frequency may be the most sensitive measure of surgically-induced, high-frequency sensorineural hearing changes. ( info)

15/46. Usefulness of 1000 Hz tone-burst-evoked responses in the diagnosis of acoustic neuroma.

    The auditory brain stem response (ABR) has become widely recognized as a sensitive and cost-effective screening modality in neuro-otologic diagnosis. However, the audiometric characteristics of the test ear may obscure the interpretation of the click-evoked ABR, particularly in the face of high-frequency hearing loss. It is often unclear whether latency delays or absent responses are attributable to retrocochlear disease or simply to the magnitude of the patient's hearing loss. The acoustic click stimulus commonly used in ABR testing activates predominantly the basilar membrane in the 2000 to 4000 Hz range. Because many cochlear and retrocochlear processes are associated mainly with hearing loss in this range, we have found it helpful in selected cases to use 1000 Hz tone-burst stimuli to circumvent the effects of elevated hearing thresholds on the ABR. In this article, our experience with the use of 1000 Hz nonlinearly gated tonebursts in 17 patients with acoustic neuroma is presented. ( info)

16/46. Use of a gonadotropin-releasing hormone agonist analogue for treatment of cyclic auditory dysfunction.

    A patient with cyclic luteal phase high-frequency hearing loss is described. This was documented by pre- and post-menstrual audiograms indicating a 40-dB hearing loss in the luteal phase. This had been long-standing and was resistant to oral contraceptive therapy. A gonadotropin-releasing hormone agonist (nafarelin) was used to inhibit ovarian function and was successful in preventing loss of hearing for the 6-month treatment period. ( info)

17/46. Eighth nerve signs in a case of multiple sclerosis.

    We evaluated a 25-year-old woman with multiple sclerosis who presented with the acute onset of a profound unilateral high-frequency, sensorineural hearing loss that resolved clinically within 10 days. Click-elicited brain stem-evoked responses were abnormal at the time of presentation and demonstrated only limited recovery over a follow-up period of 11 months. magnetic resonance imaging disclosed a lesion in the eighth nerve root-entry zone and the cochlear nucleus. Our findings in this case support the hypothesis of eighth nerve root-entry zone involvement in sudden hearing loss in multiple sclerosis and reinforce the notion that click-elicited brain stem-evoked responses are useful primarily to evaluate the high-frequency regions of the auditory system. ( info)

18/46. The need for a participatory conservation programme for the reduction of noise exposure to Thai female workers.

    hearing loss induced in thirty female workers because of exposure to continuous noise was studied in a plastic bag plant in Samutprakarn Province, the largest industrial zone in thailand. The sound level in this plant was 98.5 dBA., 94.0 dBA. and 93.0 dBA. in the weaving, winding and warping sections, respectively. Results of an audiometric test showed a significant relationship between high noise level and hearing loss at frequency 4,000 Hz. A questionnaire survey found that a relatively high number of workers had various symptoms such as: 76.7% general fatigue, 70% headache, 63.3% ear distension and 56.7% vertigo. Concerning the usage of ear protective devices, it was found that 80% of the workers have never used such devices, 16.7% occasionally used them, and 3.3% have always used cotton wool to reduce the high noise level. Their reasons for non-use of ear protective devices were 1) not provided by the employer (86.7%), 2) not necessary (83.3%), 3) accustomed to the noise (63.3%), 4) nobody uses (56.7%), and 5) no loud noise (16.7%). These results point to the need for improving the work conditions and welfare services of the workers at this plant. Also, hearing conservation programmes can be instituted in developing countries through cooperation among the safety inspectorate, the employer and the workers. ( info)

19/46. Successful renal transplantation for Epstein syndrome.

    Successful cadaveric renal transplantation was accomplished in a patient with Epstein syndrome, a triad of macrothrombocytopenia, partial high-frequency hearing loss, and nephritis, which often progresses to complete renal failure. The success of the transplant demonstrates that the macrothrombocytopenia which occurs in this syndrome is not a contraindication to aggressive management of end-stage renal disease. ( info)

20/46. Autosomal recessive progressive high-frequency sensorineural deafness in childhood.

    Autosomal recessive progressive high-frequency sensorineural deafness in childhood occurred in six patients from two families. This progressive sensorineural hearing loss starts mainly in the higher frequencies. There is an abrupt decline in the audiogram that slowly decreases with the increase of the hearing loss in the lower frequencies. ( info)
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