Otoadmittance measurements in patients with rheumatoid arthritis.

Analysis of middle ear function has for many years been accomplished by acoustic impedance measurements and this has proved of great clinical value. The vectors which contribute to impedance are functions of mass, stiffness and resistance of the system and information about these components may be obtained by use of the otoadmittance meter. The shape of the tympanogram may be altered both by pathologies which change the relative magnitude of the vectors and by variation in the probe tone frequency. Patients with rheumatoid arthritis (55 ears) were compared with a series of controls (50 ears); 38% of 'rheumatoid ears' demonstrated a marked notch on the 660 Hz susceptance curve whilst only 8% of the control group showed this abnormality. The pattern suggests a decrease in the stiffness of the transducer mechanism in rheumatoid arthritis.