A new method to analyze the subjective visual vertical in patients with bilateral vestibular dysfunction

OBJECTIVE: The aim of this study was to assess the subjective visual vertical in patients with bilateral vestibular dysfunction and to propose a new method to analyze subjective visual vertical data in these patients. METHODS: Static subjective visual vertical tests were performed in 40 subjects split into two groups. Group A consisted of 20 healthy volunteers, and Group B consisted of 20 patients with bilateral vestibular dysfunction. Each patient performed six measurements of the subjective visual vertical test, and the mean values were calculated and analyzed. RESULTS: Analyses of the numerical values of subjective visual vertical deviations (the conventional method of analysis) showed that the mean deviation was 0.326 +/- 1.13 degrees in Group A and 0.301 +/- 1.87 degrees in Group B. However, by analyzing the absolute values of the subjective visual vertical (the new method of analysis proposed), the mean deviation became 1.35 +/- 0.48 degrees in Group A and 2.152 +/- 0.93 degrees in Group B. The difference in subjective visual vertical deviations between groups was statistically significant (p < 0.05) only when the absolute values and the range of deviations were considered. CONCLUSION: An analysis of the absolute values of the subjective visual vertical more accurately reflected the visual vertical misperception in patients with bilateral vestibular dysfunction.

Otogelin: A glycoprotein specific to the acellular membranes of the inner ear

Efforts to identify the specific components of the mammalian inner ear have been hampered by the small number of neuroepithelial cells and the variety of supporting cells. To circumvent these difficulties, we used a PCR-based subtractive method on cDNA from 2-day-old mouse cochlea. A cDNA encoding a predicted 2910-amino acid protein related to mucin has been isolated. Several lines of evidence indicate, however, that this protein does not undergo the O-glycosylation characteristic to mucins. As confirmed by immunocytochemistry and biochemical experiments, this protein is specific to the inner ear. Immunohistofluorescence labeling showed that this protein is a component of all the acellular membranes of the inner ear: i.e., the tectorial membrane of the cochlea, the otoconial and accessory membranes of the utricule and saccule, the cupula of the semicircular canals, and a previously undescribed acellular material covering the otoconia of the saccule. The protein has been named otogelin with reference to its localization. A variety of nonsensory cells located underneath these membranes could be identified as synthesizing otogelin. Finally, this study revealed a maturation process of the tectorial membrane, as evidenced by the progressive organization of otogelin labeling into thick and spaced radial fiber-like structures.