Introduction:
The cochlear implant (CI) procedure in patients with inner ear malformations is challenging. The aim of this study was to evaluate auditory perception and speech development in children with enlarged vestibular aqueduct (EVA) and to relate the results to the diagnosis of Pendred syndrome (PS), imaging findings, surgical course, and postoperative period.

Material and methods:
The study group consisted of 49 children with EVA, aged 11 months to 15 years, with severe to profound hearing loss. The EVA patients included 22 with PS and 27 with nonsyndromic EVA (NSEVA). The control group consisted of 46 children with nonsyndromic deafness. Outcomes after cochlear implantation were evaluated annually for at least 10 years. Auditory performance was assessed by categories of auditory performance (CAP) and Meaningful Auditory Integration Scale (MAIS). Speech outcomes were evaluated by Speech Intelligibility Rating Scale (SIR) and Meaning Use of Speech Scale (MUSS). Genetic counselling, imaging studies, and vestibular testing were also evaluated when available.

Results:
All patients included in the study benefited from cochlear implants, especially when implantation was performed before the age of 3 years. After CI, EVA patients (PS and NSEVA) achieved a steeper rate of increase in auditory perception and speech intelligibility, demonstrating higher scores at each follow-up point compared to nonsyndromic patients (NS). There were no differences in auditory and speech perception between NSEVA and PS patients. In addition to EVA, the most commonly diagnosed malformation was incomplete partition type 2 (IP-2), the presence of which negatively affected postoperative outcomes. During cochleostomy, cerebrospinal fluid (CSF)/perilymph leakage was observed in 50% of implanted ears, but its presence did not affect the final outcomes.

Conclusions:
Early cochlear implantation is associated with satisfactory speech and auditory development in children with EVA. Due to the presence of inner ear malformations in patients with Pendred syndrome, detailed imaging of the temporal bone is indicated. Despite the frequent occurrence of CSF/perilymph leakage during cochleostomy, patients with EVA benefit satisfactorily from cochlear implantation.