A Case of Bilateral Sensorineural Hearing Loss with Different Onset Times and Severities Between the Right and Left Ears Developing During Treatment for Brain Metastases in a Patient with Lung Adenocarcinoma

The clinical/demographic backgrounds of patients with sudden sensorineural hearing loss (SSNHL) vary from healthy young people to elderly people with multiple pre-existing diseases. Herein, we report the case of a 65-year-old male lung adenocarcinoma patient with brain metastasis who presented with SSNHL in the left ear. As expected from the pre-existing disease, brain MRI suggested metastatic disease in the left internal auditory canal including the cochlear nerve fibers, as the cause of the SSNHL. With steroid administration, the pure tone audiometry thresholds on the left side improved within one week, even though the speech discrimination score of the left ear was low. After two months, further improvement of the pure tone audiometry thresholds in the left ear was observed, but the hearing level at high frequencies in the right ear was notably worse as compared with that at the patient’s first visit.