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Change of bone conduction thresholds by total footplate stapedectomy in relation to age
1Division of Otolaryngology, Head and Neck Surgery, Stanford University Medical Center, CA.
Introduction:
The influence of age on threshold changes of bone conduction after stapedectomy has not been thoroughly studied. Improvement of the Carhart notch by stapes surgery might be related to age as well as an increase in cochlear sensitivity to surgical trauma.
Patients And Methods:
A retrospective study on the outcome of stapedectomy was undertaken. The results of surgery performed on 387 ears in 315 patients for otosclerosis between 1962 and 1989 were obtained. Stapedectomy, performed by a single surgeon, consisted of total stapedectomy, seal of the oval window with tragal perichondrium, and insertion of a free tragal cartilage graft.
Results:
Analysis of bone conduction changes with stapedectomy shows an average improvement of 5 to 6 dB at 0.5, 1, and 2 kHz with best improvement at 2 kHz. At 4 kHz a mean decrease of 4 dB is recognized. The improvement of bone conduction at 2 kHz is 12 dB in patients younger than 30 years compared with 4 dB in patients older than 60 years (P < .05). The youngest group was improved by 2 dB at 4 kHz, whereas the oldest group deteriorated by 5 dB (P < .05). Age relationship was apparent in all 4 frequencies.
Conclusions:
With increasing age there is less improvement in bone conduction at 0.5, 1, and 2 kHz with correction of the Carhart notch and more deterioration at 4 kHz. The cochlear sensitivity to surgical trauma increases with age. In younger patients the preoperative bone conduction levels do not reflect the true cochlear reserve. Patients younger than 40 years of age might profit more from a partial or total footplate removal in stapedectomy, as this better corrects the Carhart notch. Patients older than 40 years of age might profit from a stapedotomy as this better preserves high frequencies.