[Possible reasons for cerebrospinal fluid gusher in cochlear implantation with inner ear abnormality]

Objective: To discuss the possible reasons for cerebrospinal fluid (CSF) gusher in cochlear implantation (CI) with inner ear abnormality. Method: A retrospective analysis was performed on 340 cases who underwent CI from January 2013 to December 2016 in Division of Otology, Otorhinolaryngology Hospital, the First Affiliated Hospital of Zhengzhou University. Among them, 96 cases had inner ear abnormalities. Imaging examinations were performed on these patients, and classification of inner ear malformation was done according to the results. Results: Among the cases with inner ear abnormality, 9.4% (9/96) suffered from CSF gusher during CI. The inner ear abnormalities were found to be as follows: 3 cases had incomplete partition type Ⅰ; 1 case had incomplete partition type Ⅰ with semicircular canal dysplasia; 1 case had common cavity deformity; 1 case had enlarged vestibular aqueducts and common cavity deformity; 2 cases had Mondini deformity. All of these cases had bony defect in the fundus of the internal acoustic meatus observed on CT scans. Another case was type 1 cochlear aqueduct with round window aplasia. Conclusions: Defects in the modiolus or fundus of the internal acoustic meatus is the main reason for CSF gusher during CI. A patent cochlear aqueduct is another possible reason.