The Effect of CO(2) and KTP laser on the cat saccule and utricle.

OBJECTIVES/HYPOTHESIS: To assess the potential carbon dioxide (CO(2)) and potassium-titanyl-phosphate (KTP) laser-related trauma to the saccule and utricle in a cat model. STUDY DESIGN: Basic science experiment utilizing cat model. METHODS: Twelve adult male cats were divided into two groups-CO(2) and KTP-to assess the potential saccule and/or utricle trauma with direct discharge of laser energy into the vestibule after the stapes was removed. Both groups were subdivided to assess the effects with acute sacrifice and three-month survival. Bone conduction auditory brain-stem response thresholds were used to monitor auditory function. Clinical observation was used to monitor vestibular function. The temporal bones were harvested, processed, and stained with hematoxylin and eosin (H&E) in all animals with the uninvolved side serving as the control. RESULTS: None of the animals demonstrated changes in bone conduction auditory brain-stem responses. None of the animals in the survival group demonstrated clinical vestibular dysfunction. Saccular and utricular wall rupture was observed in all animals sacrificed acutely. None of the saccular and utricular wall ruptures were of a size and location that could be attributed to laser trauma, and none of the saccular and utricular wall ruptures were associated with neuroepithelial trauma. CONCLUSIONS: There is no evidence of a difference between the CO(2) and KTP laser in potential laser-related trauma. Using bone-conducting auditory brain-stem response threshold and clinical monitoring of vestibular function, there was no evidence of clinical auditory or vestibular dysfunction. The histologic evidence of saccular and utricular wall rupture is more consistent with stapes extraction trauma than laser-related trauma.

Better time-intensity trade revealed by bilateral giant magnetostrictive bone conduction.

Sound lateralization tests were performed to compare the magnet coil bone-conduction headphone with the giant magnetostrictive bone-conduction headphone using 18 healthy participants. Although, no significant difference between these bone-conduction headphones was obtained for the interaural time difference and interaural intensity difference, a significant difference was obtained for the time-intensity trade. This revealed that the difference between the headphones is apparent in the integration of the heterogeneous sensations of the time and intensity difference at the cognitive level, but no difference is apparent between the homogeneous sensations of the discrimination of interaural time difference or interaural intensity difference at the sensory level. It was concluded that the difference at the cognitive level indicates the better performance of the giant magnetostrictive headphone.

Long-term sensorineural hearing deficit following radiotherapy in patients suffering from nasopharyngeal carcinoma: A prospective study.

BACKGROUND: This was a prospective study to evaluate the effect of radical external irradiation on inner ear function after treatment of nasopharyngeal carcinoma. METHODS: Pure tone audiograms were performed at regular intervals before, after, and up to 4.5 years following completion of radiotherapy. RESULTS: Two hundred ninety-four patients (526 ears) were included. Within 3 months after radiotherapy, deterioration of bone conduction threshold at 4 kHz and pure tone average (average of 0.5 kHz, 1 kHz, and 2 kHz) were noted in 164 ears (31%) and 75 ears (14%), respectively. Patients older than 50 years and ears with threshold below 60 dB at 4 kHz before radiotherapy were significant factors (p < 0.01 and p < 0. 001) associated with a 4 kHz loss. In 40% of these ears, recovery was evident at 2 years. With follow-up for 4.5 years, the probability of significant threshold deterioration increased with time. CONCLUSION: Sensorineural hearing loss started soon after radiotherapy. Early changes could be reversible while the probability of persistent hearing loss continued to increase.

Otitis media with effusion in patients with nasopharyngeal carcinoma, postirradiation.

Eighteen patients with nasopharyngeal carcinoma were subjected to eustachian tube function testing before and 6 months and 5 years after irradiation at the university hospital to investigate the chronological changes of tubal function induced by irradiation and to study the development of otitis media with effusion after irradiation. Improvement of tubal function was found 5 years after irradiation in those ears without otitis media. However, in patients who had otitis media with effusion after irradiation, deterioration of tubal function was persistent, and inflammatory reaction was detected in the upper respiratory tract, including the maxillary sinus and nasopharynx. Thus, the development of otitis media with effusion after irradiation in patients with nasopharyngeal carcinoma is attributable to both tubal and inflammatory factors. Insertion of a ventilatory tube in ears can relieve tubal obstruction but can possibly aggravate the inflammatory process. Therefore, it is our opinion that myringotomy plus local treatment may be preferable to insertion of a ventilatory tube in patients with nasopharyngeal carcinoma who have otitis media with effusion.

[Soft laser therapy in combination with tebonin i.v. in tinnitus]. / Softlasertherapie in Kombination mit Tebonin i.v. bei Tinnitus.

28 patients were treated with soft-laser therapy. Two-thirds of them had suffered from tinnitus for more than six months and had undergone different therapies before. Each patient was treated twelve times, treatment lasting ten minutes. Before therapy six ml of Tebonin were given i.v. Four minutes later, the laser was positioned at a distance of one centimetre from the patients' mastoid. The laser beam was directed two fingers above the mastoid tip aiming at the lateral wall of the contralateral orbit. Before and three weeks after treatment each patient underwent pure tone audiometry and determination of the tinnitus intensity. Patients were asked to score symptoms before and three weeks after therapy. Hearing levels before and after soft-laser therapy did not show any statistic difference. Three weeks after the last treatment, twenty patients denied any change in tinnitus. Two patients felt an improvement of tinnitus and one patient had recovered completely. Five patients remained undecided about the outcome of therapy. To sum up, according to our results, the trial so far failed to show clear benefits of soft-laser therapy for patients suffering from chronic tinnitus.

Effects of radiation on hearing in patients with malignancies of head and neck.

Patients with normal hearing at the start of radiation were tested for hearing during (30 GY) and at the end of radiation therapy (45-60 GY) in order to determine if there was any alteration in their pure tone hearing thresholds. A significant increase in the hearing threshold was found at high frequencies at the end of therapy. At the end of the course of radiation, clinical findings suggestive of middle ear changes due to radiation were seen in 33% of the ears. Patients whose ears are included in the field of radiation may have to be forewarned to expect a loss in their acuity of hearing, especially those whose professional life may depend on it.

Effects of X-ray irradiation on hearing in guinea pigs.

Effects of X-ray irradiation on the hearing with CM and ABR to both air- and bone-conduction stimuli were studied continuously from immediately after the irradiation to a few weeks later. At 2, 4, and 6 krad, only slight conductive hearing impairment was found, but at 8 krad or more, CM and ABR disappeared abruptly, after having increased briefly. Advanced sensorineural hearing loss appeared at about 10 hours after irradiation ended at 8 krad, at about 6 hours at 10 krad, and at about 3 hours at 12 krad. More severe hearing impairment was observed at higher frequencies and the endocochlear d.c. potential (EP) decreased at about 7 hours after 10 krad irradiation. Histologically, no discernible changes in the hair cells or sensory hairs were found with a scanning electron microscope at about 6 hours after 10 krad irradiation, while with a transmission electron microscope, the outer hair cells in the basal coil of the cochlea were found to be mostly destroyed. However, no changes could be found in the inner hair cells or other supporting cells.