Sensorineural Hearing Loss in Chronic Otitis Media

Conductive hearing loss due to chronic otitis media (COM) can be treated by surgery. COM, however, may be associated with functional damage to the inner ear. Sensorineural hearing loss (SNHL) due to COM has been found to be significant by some authors, whereas it has been considered negligible by others. The present study aimed to answer the question Does COM cause SNHL ?

120 patients with unilateral COM admitted for tympano-mastoidectomy were selected for this observational case-control study. Air conduction threshold (ACT) and bone conduction threshold (BCT) averages were calculated at the speech frequencies (500, 1000, 2000Hz) and 4 KHz, in affected (case ear) and non affected (control ear) and then entered in the questionnaire along with intraoperative findings. Multiple statistical tests were used to clarify the relationships between SNHL and COM.

COM was seen to be associated with SNHL. The Threshold shift was more accentuated at 4 KHz in older patients. SNHL at 4 KHz seemed to be higher than that at the speech frequencies. There was a significant positive relationship between the elevated BCT and duration of COM. The relationship between elevated BCT and cholesteatoma was also significant.

The inner ear is vulnerable to COM. The proximity of the sensory cells to the potential source of harm (inflamed middle ear) may mean higher exposure, as reflected by the fact that sensory cells processing high frequencies are more seriously damaged. SNHL in affected ear is strongly dependant on duration of disease.