[Changes in bone conduction in the surgery of chronic otitis and its sequelae (evaluation of 800 operations)].

The authors undertook a study of changes in bone conduction (BC) during 800 operations carried out over a 5 years period (1979-1984) for chronic otitis or sequelae of chronic otitis. After elimination of ears with deafness (47) and cases unsuitable for evaluation (39), they finally included 714 records in the study. Only comparison of free and post-operative BC was made and using 4 conversational frequencies, not taking into account a deviation of 5 DB for each of these 4 frequencies. The study involved 317 myringoplasties: In 271 (i.e. 85,5%) there was no change in BC. Amongst them, 37 patients nevertheless showed a transient fall in BC. Of particular importance is the fact that almost 1/3 (11 to be exact) recovered only during the 2nd semester following surgery, a period which was even exceeded in the other 5 cases. 46 (i.e. 14.5%) were classified as "permanent" falls in BC. Amongst these in only 17 (i.e. 5%) were there "only" the three standard aggression factors for the I.O.: aspiration--scraping--manipulation of the tympano-ossicular system, without it being possible to attribute a predominant role to one more than the other. With regard to reaming of the E.A.M., those cases in which this could be considered responsible appeared to be infinitesimal. Furthermore, there was no statistically significant difference (reduced deviation test--"chi"2 test) between the number of falls in BC seen following myringoplasty with or without reaming. 83 tympanoplasties by Piston-Malleus, study of which led to the same conclusions as for myringoplasties. 118 masto-atticotomies, including 23 with posterior tympanotomy. Despite peri-labyrinthine and peri-ossicular scraping, results were essentially identical. 196 evacuation cavities (227-31 deafness) of which somewhat less than half only (46%) were ears undergoing surgery for the first time. Percentage of unchanged BC was here much more unfavourable, with 49 "permanent" falls in BC, i.e. 25%, of which, it must be said, 5 were minimal falls, and with, in 25 cases, a follow-up of less than 3 months.