Peripheral Vestibular System Histopathologic Changes following Head Injury without Temporal Bone Fracture.

Abstract

Vestibular symptoms such as dizziness and vertigo are common after head injury and may be due to trauma to the peripheral vestibular system. The pathophysiology of peripheral vestibular symptoms following head injury without temporal bone (TB) fracture, however, is not well understood. Herein, we investigate the histopathology of the peripheral vestibular system of patients who sustained head injury without a TB fracture. Otopathology study. Otopathology laboratory. TB of subjects with a history of head injury without TB fractures were included and evaluated by light microscopy. Specimens were assessed for qualitative and quantitative characteristics, such as number of Scarpa's ganglion cells in the superior and inferior vestibular nerves, vestibular hair cell and/or dendrite degeneration in vestibular end organs, presence of vestibular hydrops, and obstruction of the endolymphatic duct. Five cases (n = 5 TBs) had evidence of vestibular pathology. There was a decrease of 48.6% (range, 40%-59%) in the mean count of Scarpa's ganglion cells as compared with that of normative historical age-matched controls. Moderate to severe degeneration of the vestibular membranous labyrinth was identified in the posterior, superior, and lateral canals in several cases (50%, n = 4 TBs). The maculae utriculi and sacculi showed mild to severe degeneration in 2 cases. Additional findings include vestibular hydrops (25%, n = 2 TBs) and blockage of the endolymphatic duct (n = 1 TB). Otopathologic analysis of patients with a history of head injury without TB fracture demonstrated peripheral vestibular otopathology. Future studies are necessary to determine if otopathology findings are directly attributable to head injury.