Homograft tympanoplasty in perspective. A long-term clinical-histologic study of formalin-fixed tympanic membranes used for the reconstruction of 125 severely damaged middle ears.

Abstract

This seven and a half year clinical-histologic study evaluates the effectiveness of buffered, formaldehyde-fixed homograft tympanic membranes for reconstructing the severely damaged middle ear in 125 consecutive patients. Indications for use of homograft tympanoplasty were limited to those cases in which standard tympanoplasty had already failed to produce a satisfactory hearing or anatomic result (i.e., recurrent perforations or draining radical mastoidectomy cavity), or to those cases in which there was a high risk of unsatisfactory result with standard tympanoplasty techniques (i.e., total perforation with absent malleus or congenital aural atresia). Anatomic data was documented with serial postoperative photomicrography. Audiograms were performed at yearly intervals and long-term hearing results were analyzed. Histologic studies were performed on 2 homograft tympanic membranes removed 6 months and 6 years postoperatively. Postoperative photographs of the healing donor tympanic membrane and histologic studies confirmed that the homograft collagen attracts host angioblasts, fibroblasts and epithelial cells. The initial inflammatory response (primarily lymphocytic) subsides and the host produces collagen and elastin fibers interspersed among the donor collagen. Gradually the donor collagen is resorbed. At the completion of this study, 95% (119/125) of the homograft tympanoplasties are currently intact. There were 13 immediate postoperative perforations, but 11 were repaired with a second stage underlay fascia tympanoplasty. Long-term hearing results were analyzed according to the type of ossicular reconstruction employed (mean follow-up 4 years). In 87 patients with chronic otitis media, 94% of the type I repairs maintained an air-bone gap of 25 dB or less, 85% of the type II, and 81% of the type III. Forty-four patients presented with an absent malleus and absent tympanic membrane and were reconstructed with a homograft tympanic membrane with attached malleus and a shaped incus columella. At 4 years postoperatively, 83% of these patients maintained an average air-bone gap of 25 dB or better. A similar group of 38 patients presenting with absent malleus, incus, and stapes were reconstructed with isograft temporalis fascia and a cartilage covered TORP. Only 18% of the TORP patients maintained an air-bone gap of 25 dB 4 years postoperatively. Thirty-three patients with draining radical mastoidectomy cavities were reconstructed; 97% (32/33) had a dry, self-cleansing ear with no activity restriction. Only 59% maintained an air-bone gap closure of 25 dB or better in the long-term follow-up; 30% (10/33) developed persistent eustachian tube dysfunction, usually in the second through fourth postoperative years.(ABSTRACT TRUNCATED AT 400 WORDS)