Suprameatal Cochlear Implantation in a CHARGE Patient With a Novel CHD7 Variant and KALLMANN Syndrome Phenotype: A Case Report

Objective: We present the clinical findings, technique of the suprameatal cochlear implantation, postoperative auditory results, and genetic analysis of the CHD7 gene. Patient: A 19-year-old Japanese woman was referred because of progressive hearing loss since early childhood. She had used verbal language for the main mode of communication until the age of 17. Examination revealed coloboma, heart defect, choanal atresia, genital hypoplasia, and deafness, which was diagnosed as CHARGE syndrome. Examination also revealed features of Kallmann syndrome. Interventions: Cochlear implantation was performed in the left ear at age 20. Targeted resequencing of the CHD7 gene was performed by next-generation sequencing. Results: Cochlear implantation was performed using a suprameatal approach (SMA) with cartilage protection because of a venous malformation of the temporal bone. The electrode introduced into the scala tympani through the cochleostomy could be fully inserted. The electrode was covered with cartilage to avoid contact with the skin of the external auditory canal. No intra-or postoperative complications have occurred up to 4 years postoperatively, and the patient uses verbal language again as the main mode of communication. A novel variant c.6405_6406delAG,p.(Ala2137Argfs*2) in CHD7 was identified by next-generation and Sanger sequencing analyses, resulting in a 2137-amino-acid truncated polypeptide. Parental genetic screening confirmed the sporadic origin of the mutation. Conclusion: Cochlear implantation surgery using the SMA with cartilage protection technique appears to be a feasible and effective option for patients with ear anomalies that obstruct the usual approach. A novel frameshift variant c.6405_6406delAG,p.(Ala2137Argfs*2) in CHD7 was also identified in this patient.