In the case reported evaluation of unilateral endocochlear deafness in a 44-year-old man led to a diagnosis of a small intracanalicular neurinoma of the cochlear nerve which had invaded the first turn of the cochlear spiral.
Gersdorff, M., Decat, M., Duprez, T., & Deggouj, N. (1996). Intracochlear schwannoma. European Archives of Oto-Rhino-Laryngology, 253(6), 374-376. https://hdl.handle.net/2078.5/65256 (Original work published 1996)