Complement activation in sudden deafness.

OBJECTIVE To test whether complement activation is associated with sudden deafness. DESIGN Plasma samples obtained from patients in the acute phase of sudden deafness were analyzed for complement activation measured by C3bc levels and terminal complement complex. Comparisons were made with plasma samples from healthy controls. PATIENTS Twenty-five adult patients with unilateral sudden deafness. The criteria for inclusion were symptoms of hearing loss for not longer than 14 days and a hearing loss of 35 dB or more measured at entry. RESULTS Levels of C3bc were higher in patients compared with controls (P<.001). There were no differences in the formation of terminal complement complex in patients and controls. CONCLUSIONS The elevated levels of C3bc in patients with sudden deafness indicate an activation of the first part of the complement cascade and therefore suspected inflammatory causes. Measurements of C3bc levels might identify patients with sudden deafness who would benefit from treatment with anti-inflammatory drugs.