[Cogan syndrome as a rare cause of deafness].

Cogan syndrome is a rare systemic disease characterized by the occurrence of audiovestibular and ocular symptoms. We present the case of a 62-year-old female patient who received a cochlear implant after unilateral deafness. Despite successful implantation, the disease progressed with chronic headache, recurrent otitis, fluctuating intracochlear impedances, and slowly progressing hearing loss in the contralateral ear. Through interdisciplinary collaboration, the diagnosis of Cogan syndrome was established, and biological therapy was initiated.