Typewriter tinnitus: An investigative comparison with middle ear myoclonic tinnitus and its long-term therapeutic response to carbamazepine.

OBJECTIVES

Due to its rarity and similar sound, typewriter tinnitus (TT) can be misdiagnosed as middle ear myoclonic tinnitus (MEMT). We aim to clarify the characteristics of TT compared to MEMT, and the long-term therapeutic response to carbamazepine.

METHODS

Fourteen patients with TT and 28 patients with MEMT were enrolled.

RESULTS

TT patients were older than MEMT patients, and their tinnitus symptoms were mostly unilateral. Tinnitus symptoms, which is associated with dizziness, facial spasm, and head motion, were more common in TT, whereas MEMT were more related to noise. Acoustic reflex decay perturbation and low loudness discomfort level were diagnostic signs in MEMT patients, while decreased level of wave II in ABR was the most reliable sign in TT patients. All TT patients exhibited partial or complete response to carbamazepine, but there was a relapse rate after withdrawal of the drug was 60%. Increase in age and longer duration of symptoms were the risk factors of relapse of TT.

CONCLUSION

The different characteristics observed in this study will be helpful to diagnose TT and MENT. Duration of tinnitus was the most important long-term prognostic factor of the carbamazepine trial, which indicates the importance of its earlier diagnosis.