Size of typmanic membrane perforation and hearing loss

This prospective study was done to assess the level of preoperative hearing impairment in different sizes of pars tensa perforation in patients with chronic suppurative otitis media (CSOM) tubo-tympanic type undergoing myringoplasty. A total of 50 patients were recruited from the outpatient Department of Otorhinolaryngology - Head and Neck Surgery from June 2003 to May 2004. Cases of CSOM tubo-tympanic type with dry central perforation, conductive type of hearing loss were subjected to myringoplasty. Preoperative audiometric evaluations were done. While operating under microscope diameter of perforations were measured and perforations were grouped according to the size. It was observed that greater hearing loss was reported in group D perforation (44 dB), where as in group A, it was 31 dBHL. The average hearing loss at 500 Hz was 46.40 dB, at 1000 Hz was 30.90 dB and at 2000 Hz it was 31.9 dB. This shows that the hearing loss is more at lower frequencies and less as the frequencies increase. This study shows that as the size of perforation is increased, the hearing loss also increases. The hearing loss is more marked at lower frequencies as compared to higher frequencies.