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A method for quantitative assessment of vestibular otopathology
1Department of Otolaryngology and Otopathology Laboratory, Massachusetts Eye and Ear Infirmary, Boston 02114, USA.
Background:
Quantitative studies of the vestibular system using serial sections from human temporal bones have been limited because it has been generally difficult to reliably differentiate hair cells from supporting cells and type I from type II hair cells.
Objectives:
1. To develop a new method to overcome the above limitations and permit quantitative assessments of types I and II vestibular hair cells in archival temporal bone sections. 2. To demonstrate that this method is reliable, valid, and repeatable. 3. To describe the advantages of this method compared with other traditional techniques. 4. To discuss the potential of this method to provide new insight into the etiology, pathology, and pathophysiology of vestibular disorders.
Study Design:
Examination of archival human temporal sections prepared for conventional light microscopy.
Methods:
The method used Nomarski (differential interference contrast) microscopy to permit visualization of the cuticular plate and stereociliary bundle, to allow unambiguous identification of hair cells. Types I and II hair cells were distinguished by their morphological characteristics. The method was used to measure the density of types I and II hair cells in each vestibular sense organ. Raw-density counts were corrected for potential double counting using Abercrombie's formula.
Results:
Intrarater and interrater reliability was strong as judged by high Pearson and Spearman correlation values (P < .01). Abercrombie's formula was shown to be valid by comparison with counts made by an unbiased calibration technique using the optical disector principle (correlation coefficients > 0.9, P < .01).
Conclusions:
The method described in this report has several advantages when compared with alternative techniques such as surface preparations. The method is applicable to archival bones, permits simultaneous evaluation of the rest of the labyrinth, is relatively inexpensive, and does not preclude other techniques of study (e.g., polymerase chain reaction and immunostaining). Case studies of temporal bones with aminoglycoside ototoxicity and Meniere's disease are used to show how this method has the potential to provide new insight into the pathology and pathophysiology of vestibular disorders.