Unbiased Scarpa's Ganglion Neuronal Count Using Stereology in Ototoxicity

Abstract

Objectives: To obtain unbiased stereologic estimates of the vestibular ganglion neuronal number from 7 subjects with a history of gentamicin (n = 3) and streptomycin (n = 4) aminoglycoside ototoxicity, and compare the results with those from normative age-matched controls.

Methods: Specimens from the archival temporal bone collection from subjects with a history of aminoglycoside toxicity were used. Normative age-matched controls were used. Estimates were obtained using the optical fractionator unbiased stereologic technique. The group means were compared using unpaired, 2-tailed student t test. Significance was set at 0.05.

Results: The average total number of vestibular ganglion neurons in the aminoglycoside group was 20,733 (CV = 0.073). The average total number of vestibular ganglion neurons in the age-matched normal subjects was 24,902 (CV = 0.109). The vestibular ganglion neuronal count was significantly reduced in the aminoglycoside group (^P = 0.0039).

Conclusion: This study uses an unbiased stereologic technique to demonstrate a significant decline in the number of vestibular ganglion neurons in patients with a documented history of streptomycin and gentamicin ototoxicity. The decline may be secondary to deafferentation or to a direct effect of aminoglycosides on the ganglion.