Predicting hearing thresholds in occupational noise-induced hearing loss by auditory steady state responses.

OBJECTIVES: Currently available behavioral tools for the assessment of noise-induced hearing loss (NIHL) depend on the reliable cooperation of the subject. Furthermore, in workers' compensation cases, there is considerable financial gain to be had from exaggerating symptoms, such that accurate assessment of true hearing threshold levels is essential. An alternative objective physiologic tool for assessing NIHL is the auditory steady state response (ASSR) test, which combines frequency specificity with a high level of auditory stimulation, making it applicable for the evaluation of subjects with a moderate to severe deficit. The primary aim of the study was to assess the value of the multifrequency ASSR test in predicting the behavioral warble-tone audiogram in a large sample of young subjects with NIHL of varying severity or with normal hearing. The secondary goal was to assess suprathreshold ASSR growth functions in these two groups. DESIGN: The study group included 157 subjects regularly exposed to high levels of occupational noise, who attended a university-associated audiological clinic for evaluation of NIHL from 2009 through 2011. All underwent a behavioral audiogram, and on the basis of the findings, were divided into those with NIHL (108 subjects, 216 ears) or normal hearing (49 subjects, 98 ears). The accuracy of the ASSR threshold estimations for frequencies of 500, 1000, 2000, and 4000 Hz was compared between groups, and the specificity and sensitivity of the ASSR test in differentiating ears with or without NIHL was calculated using receiver operating characteristic analysis. Linear regression analysis was used to formulate an equation to predict the behavioral warble-tone audiogram at each test frequency using ASSR thresholds. Multifrequency ASSR amplitude growth as a function of stimulus intensity was compared between the NIHL and normal-hearing groups for 1000 Hz and 4000 Hz carrier frequencies. RESULTS: In the subjects with NIHL, ASSR thresholds to various frequencies were significantly and highly correlated with the behavioral warble-tone thresholds; Pearson correlation coefficients ranged from 0.6 to 0.8 over the four frequencies tested. Differences between thresholds ranged from 10 to 13 dB. The configuration of the ASSR waveforms closely approximated the behavioral audiogram. The sensitivity for screening hearing thresholds was 92%; by frequency, sensitivity ranged between 92.7 and 98.4%, but specificity was lower, especially at the low frequencies. ASSR accurately predicted moderate and severe NIHL. The mean ASSR growth amplitude to increasing stimulus level for 1000 and 4000 Hz was significantly steeper in the NIHL than in the normal-hearing group, with no significant difference between frequencies. CONCLUSIONS: The ASSR test has a high sensitivity to detect moderate to severe hearing loss in subjects with NIHL. Its use can facilitate the early identification of noise-exposed workers with NIHL. It may also serve an important medico-legal function in cases of workers' compensation. The ASSR test is not, by itself, an appropriate tool for hearing screening in the general population.

Fungal malignant external otitis.

OBJECTIVE: To investigate the clinical characteristics and outcome of fungal malignant external otitis (MEO). METHODS: The files of 60 patients treated for MEO in 1990-2008 at a tertiary medical center were reviewed for clinical characteristics and outcome, and findings were compared between patients with fungal and nonfungal infection. RESULTS: Mean duration of follow-up was 4 years. Nine patients (15%) had fungal disease; the main pathogen was Candida spp. Compared with the nonfungal MEO group, patients with a fungal infection were younger at diagnosis (average 68 vs. 74 years, p = 0.01) and had more facial nerve palsies (55% vs. 14%, p = 0.01), fewer positive bacterial cultures at presentation (33% vs. 75%, p = 0.02), and higher rates of surgery (78% vs. 18%, p = 0.0008) and hyperbaric treatment (78% vs. 4%, p = 0.0001). Eighty-nine percent had persistent infection (>2 courses of systemic antibiotics before antifungal treatment) compared with 12% in the nonfungal group (p = 0.0001). Fungal disease was associated with more persistently positive imaging findings (87.5% vs. 25%, p = 0.0001). There was no significant between-group difference in survival. CONCLUSION: Fungal MEO probably occurs secondary to prolonged antibiotic treatment for bacterial MEO. The fungal disease is more invasive than the bacterial disease, although survival is the same. Treatment should be aggressive and hyperbaric oxygen therapy should be considered.

Animal model of cochlear third window in the scala vestibuli or scala tympani.

HYPOTHESIS: The auditory impact of a cochlear third window differs by its location in the scala vestibuli or scala tympani. BACKGROUND: Pathologic third window has been investigated primarily in the vestibular apparatus of animals and humans. Dehiscence of the superior semicircular canal is the clinical model. METHODS: Fat sand rats (n = 11) have a unique inner-ear anatomy that allows easy surgical access. A window was drilled in the bony labyrinth over the scala vestibuli in 1 group (12 ears) and over the scala tympani in another (7 ears) while preserving the membranous labyrinth. Auditory brain stem responses to high- and low-frequency stimuli delivered by air and bone conduction were recorded before and after the procedure. RESULTS: Scala vestibuli group: preoperative air-conduction thresholds to clicks and tone-bursts averaged 8.3 and 9.6 dB, respectively, and bone-conduction thresholds, 4.6 and 3.3 dB, respectively; after fenestration, air-conduction thresholds averaged 40.4 and 41.8 dB, respectively, and bone-conduction thresholds, -1 and 5.6 dB, respectively. Scala tympani group: preoperative air-conduction thresholds to clicks and tone-bursts averaged 8.6 dB each, and bone-conduction thresholds, 7.9 dB and 7.1 dB, respectively; after fenestration, air-conduction thresholds averaged 11.4 and 9.3 dB, respectively, and bone-conduction thresholds, 9.3 and 4.2 dB, respectively. The changes in air- (p = 0.0001) and bone-conduction (p = 0.04) thresholds were statistically significant only in the scala vestibuli group. CONCLUSION: The presence of a cochlear third window over the scala vestibuli, but not over the scala tympani, causes a significant increase in air-conduction auditory thresholds. These results agree with the theoretic model and clinical findings and contribute to our understanding of vestibular dehiscence.

KTP/532 YAG laser treatment for allergic rhinitis.

BACKGROUND: The purpose of this study was to investigate the efficacy of the KTP/532 YAG laser to reduce nasal congestion and discharge in patients with allergic rhinitis. METHODS: Forty-eight patients with symptoms of allergic rhinitis were treated with the KTP/532 laser. All had positive skin tests for common allergens. Treatments were provided on an ambulatory basis in one to three sessions under local anesthesia with lidocaine nose spray. Outcome was determined by daily symptom reports and regular endoscopy examination and interviews for 12 months. RESULTS: Treatment was very well tolerated. There were no major side effects. At examination after 1 year, nasal obstruction was improved in 69% and nasal discharge in 40% of cases. CONCLUSION: The KTP/532 YAG laser is effective for the treatment of nasal obstruction and discharge. Comparison with other techniques showed it to be the most effective in reducing nasal discharge. It can be done as an office procedure and does not damage the nasal mucous membrane. The KTP/532 YAG laser is effective as an additional treatment for patients refractory to medication.

Revision parathyroidectomy guided by intraoperative radionuclide imaging.

BACKGROUND: Technetium-99m sestamibi scintigraphy has become one of the most popular techniques for localization of the parathyroid gland after failure of primary neck exploration. OBJECTIVE: To examine the efficacy of sestamibi with the hand-held gamma ray detecting probe for the identification of parathyroid adenomas during revision parathyroidectomy. METHODS: We reviewed six cases of probe-assisted neck exploration for parathyroid lesions following unsuccessful primary exploration. RESULTS: In all cases the pathologic glands were successfully detected and removed. CONCLUSIONS: With careful planning, a gamma ray detecting probe can be used optimally 2-3 hours after technetium-99m sestamibi injection. The probe is efficient, easy and convenient to use.