Otopathologic Patterns of Cellular Degeneration in the Peripheral Vestibular Organ Secondary to Head Trauma

Objective: This study examined patterns of cellular and neural degeneration in the peripheral vestibular system following head trauma, comparing cases with and without skull/temporal bone fractures. Methods: We analyzed 26 temporal bones (17 cases) with head trauma with fractures (six cases, nine ears) and ones without fractures (11 cases, 17 ears). Appropriate age-matched control groups comprising temporal bones without temporal bone pathology were included for comparative purposes. Histopathological analyses included counts of Scarpa's ganglion cells (ScGCs) in the superior and inferior vestibular nerves (SVN and IVN), and counts of vestibular hair cells (HCs) in the utricle, saccule, lateral semicircular canal (LSCC), and posterior semicircular canal (PSCC). Mann-Whitney U tests were used for statistical analyses. Results: The group without fractures showed a significant reduction in total ScGCs (SVN + IVN) compared to controls (p = 0.040), with a pronounced decrease in the SVN (p = 0.014). Significant reductions in type I and type II HCs were observed in the utricle (p = 0.008 and p = 0.035) and in type I HCs in the LSCC (p = 0.037). In the group with fractures, only type I HCs in the utricle were significantly reduced (p = 0.038). Conclusion: Head trauma without fractures is associated with more severe vestibular cell degeneration and greater loss of ganglion cells in the SVN in our specimens. These findings suggest that head trauma without fractures may pose a higher risk for vestibular cell damage compared with trauma with fractures.