残存聴力活用型人工内耳（EAS)例

EAS (electric and acoustic stimulation) is a hybrid system which has two parts, a cochlear implant and a hearing aid. This system is useful for patients with residual acoustic hearing in the lower frequencies. Herein, we report one case in which EAS implantation was useful. The patient was a 23-year-old woman with bilateral hearing loss from childhood. She had residual hearing at low tones. She had the greatest difficulty while having a conversation with someone. She complained of dizziness and vertigo sometimes. Equilibrium function testing showed bilateral vestibular hypofunction of the inner ear. CT and MRI revealed no inner ear anomalies. We treated this patient by EAS implantation. Complete hearing preservation at low frequencies was achieved at 1 year and 6 months after the operation. Speech discrimination testing at 6 months after the operation revealed marked improvement of monosyllable recognition from 50% to 95%. The c-VEMP at 1 year after the operation was normal. These results indicate that EAS may be useful for patients with residual hearing.