Effects of arginine vasopressin on auditory brainstem response and cochlear morphology in rats.

OBJECTIVE: This study was conducted to evaluate the relationship between hearing and cochlear histopathology after arginine vasopressin administration in rats. METHODS: A total of 30 Wistar rats were injected with either 0.02 unit/g of arginine vasopressin or the same amount of isotonic saline solution. The initial auditory brain stem response threshold was recorded and additional measurements were made at 10, 30, 60, and 90 min after injection of arginine vasopressin or isotonic saline solution. The threshold for each timepoint was compared with the initial threshold. Histological quantitative assessment of endolymphatic hydrops in the cochlea was performed using light microscopy and assessment of the basal, intermediate, and marginal cells of the stria vascularis was performed with electron microscopy. RESULTS: The auditory brain stem threshold 60 min after arginine vasopressin injection increased significantly in comparison with the initial threshold (P<0.05). Although the index for endolymphatic hydrops in rats administered arginine vasopressin was not different from that in controls (P>0.05), vacuoles in the intermediate cells were increased significantly in the treated rats (P<0.01). CONCLUSION: Hearing impairment was detected without endolymphatic hydrops in rats administered arginine vasopressin. An increase of vacuoles in the intermediate cells may account for the hearing impairment induced by arginine vasopressin injection.

Inner-ear function test in cases of posterior canal-type benign paroxysmal positional vertigo.

Otolaryngologists typically perform diagnoses and offer medical treatment for vestibular dysfunction. This vestibular dysfunction manifests as benign paroxysmal positional vertigo (BPPV), Ménière's disease, vestibular neuronitis, and so on. The etiology of BPPV is still not clear, so in this article we discuss inner-ear function, etiology, and factors related to BPPV. We examined by pure-tone audiometry and hot and cold caloric tests patients whom we identified as having diagnosed posterior canal-type BPPV. We observed canal paresis at a high rate on the affected side (p < .01). The term of recovery at the first treatment was longer in patients with canal paresis as compared to those without. Deterioration of hearing level was observed more frequently on the affected side (p < .01). The horizontal semicircular canal and cochlea are important potential sites of lesions affecting posterior canal-type BPPV, and the posterior circular canal and otolith are already considered to be sites of affecting lesions.

Correlation between arteriosclerotic changes and prognosis in patients with peripheral vestibular disorders.

Symptoms such as vertigo and unsteady gait occur in various diseases and are among the relatively common chief complaints. Even at present, the mechanisms underlying these disorders are unclear. We report a significant correlation between a prolonged period of resolution of benign paroxysmal positional vertigo (BPPV) and histories of lifestyle-related illnesses. We consider the possibility of correlating between BPPV prognosis and arteriosclerotic changes. Using carotid ultrasonography, we examined maximum intima-media thickness (IMT), maximum common carotid artery IMT, and biochemical examinations in 105 patients with peripheral vertigo. We divided patients with BPPV into groups with and without abnormal thickness of the IMT. The maximum IMT was 1.35 mm in patients with peripheral vestibular disorders. The proportion of peripheral vestibular disorder patients with a maximum IMT of > or = 1.1 mm (i.e., thickening) was 58%. The rate at which the feeling of positional vertigo remained at the halfway point in the observation period was significantly higher in the group of patients with an IMT of > or =1.1 mm (p = .0007). Our results indicate that cervical ultrasonography is useful for noninvasive examination of arteriosclerotic changes in patients with peripheral vestibular disorders. We saw indications that such patients show progression of arteriosclerotic changes. This study suggested that the arteriosclerotic change was related to prognosis.

Arteriosclerotic changes as background factors in patients with peripheral vestibular disorders.

Symptoms such as vertigo and unsteady gait occur in various diseases and are among the relatively common chief complaints. Even at present, the mechanisms underlying these disorders are unclear. We considered the possibility of peripheral vestibular disorders correlating with lifestyle-related illnesses. Under these circumstances, we assessed correlations of lifestyle-related illness as background factors for peripheral vestibular disorders and associated arteriosclerotic changes. Using carotid ultrasonography, we assessed maximum intima-media thickness (max IMT) and maximum common carotid artery IMT and evaluated biochemical examinations in 85 patients with peripheral vertigo. The patients were divided into two groups: those with benign paroxysmal positional vertigo (BPPV) and those with peripheral vestibular disorders. The frequency of abnormal IMT was significantly higher in those in the BPPV group. Calculating for average age, max IMT was significantly higher in the BPPV group. The correlation coefficient between age and max IMT was 0.343 (p < .001). All other correlation coefficients also reached statistical significance. Our results indicate that cervical ultrasonography is useful for noninvasive examination of arteriosclerotic changes in patients with peripheral vestibular disorders. Our results also indicated that peripheral vestibular disorder patients show progression of arteriosclerotic changes.

Water may cure patients with Meniere disease.

OBJECTIVES/HYPOTHESIS: We examined whether sufficient water intake is effective in the long-term control of vertigo and hearing activity in patients with Meniere disease (MD) for whom conventional therapy has proven unsuccessful. STUDY DESIGN: The authors conducted a time-series study with historical control. METHODS: Eighteen patients with MD in group 1 drank 35 mL/kg per day of water for 2 years. Twenty-nine patients with MD treated with the conventional dietary and diuretic therapy for more than 2 years during 1992 to 1999 at the same hospital were enrolled in a historical control of group 2. RESULTS: Patients in group 1 dramatically relieved vertigo and significantly improved in the hearing of the worst pure-tone average of three frequencies (0.125, 0.25, and 0.5 kHz) (low PTA) during the last 6 months of the study period. In contrast, patients in group 2 became worse in both the four- (0.5, 1, 2, and 4 kHz) frequency PTA and the low PTA, although their vertigo did improve. The number of patients whose hearing were improved, unchanged, and worse were 4, 12, and 2 in group 1 and 2, 11, and 16 in group 2, respectively. CONCLUSION: Deliberate modulation of the intake of water may be the simplest and most cost-effective medical treatment for patients with MD. Larger studies will be needed to confirm these results in a larger patient cohort.

Three-dimensional reconstruction of the human semicircular canals and measurement of each membranous canal plane defined by Reid's stereotactic coordinates.

OBJECTIVES: Equations for estimating the planar relationships of the human semicircular canals were devised by Blanks et al from a dissected bony labyrinth in a human skull. However, a similar study on the membranous semicircular canal planes has never been published. METHODS: In this study, the angle between each membranous canal plane and Reid's stereotactic horizontal plane was measured on serial histologic sections of 7 temporal bones from Japanese adults. We reconstructed the 3 semicircular canals by computer-aided 3-dimensional analysis. The angles between each pair of both bony and membranous canal planes were measured. RESULTS: In the bony labyrinth, the angles between the 2 canal planes of the lateral-anterior, anterior-posterior, and lateral-posterior pairs were 90.51 degrees +/- 2.98 degrees (mean +/- SD), 91.70 degrees +/- 1.85 degrees, and 94.52 degrees +/- 3.32 degrees, respectively. The angles between the 2 membranous canal planes of the lateral-anterior, anterior-posterior, and lateral-posterior pairs were 90.05 degrees +/- 4.74 degrees, 91.03 degrees +/- 2.93 degrees, and 91.92 degrees +/- 5.22 degrees, respectively. CONCLUSIONS: The data from our study of the membranous labyrinth showed that the angles between each canal plane and the others were much closer to 90 degrees than was found by Blanks et al for the bony labyrinth.

Three-dimensional analysis of morphological aspects of the human utricular macula.

The 3-dimensional shape of the human utricular macula and its orientation in the skull are quantitated in this report, which is one of a series. The semicircular canals and utricular macula were reconstructed in 3 dimensions on a computer from 3 human temporal bones. The 238 to 279 triangles in the entire area of the utricular macula were made by drawing lines between 2 adjacent points every 200-microm width of the utricular macula in each section. We calculated the angles between each triangle and each estimated standard axis in the skull. This study provides standard data regarding the 3-dimensional morphological aspects of the utricular macula for further investigation of the function of the utriculus. We determined that the 3-dimensional shape of the utricular macula was not a plane, but was a curved surface like that of an ellipsoid. We believe this shape is necessary for the utricular macula to detect wide-range linear acceleration.