Absorbable gelatin sponge (Gelfoam) has been used for many years in middle ear surgery. Although the sponge is generally well tolerated, fibrosis occasionally forms in the mesotympanum; some studies indicated that the absorbable gelatin sponge may be responsible. Many of these studies lack statistical analysis. We prospectively studied three absorbable hemostatic agents in the middle ear of adult male Sprague-Dawley rats to determine which promotes fibrosis to the greatest degree: absorbable gelatin sponge (Gelfoam), absorbable gelatin sheet (Gelfilm), or absorbable collagen sheet (Instat). The materials were implanted in the middle ear through a post-auricular approach and the temporal bones were serially harvested at different time intervals so we could examine histologic changes. The nonimplanted ear served as surgical control. Examination of the specimens at 6, 8, and 10 weeks by light microscopy revealed that although absorbable gelatin film and collagen-absorbable hemostat are well tolerated in this animal model, absorbable gelatin sponge promoted the presence of fibrosis to a significantly greater degree, (p = 0.0344). We conclude that absorbable gelatin sponge promotes fibrosis more frequently than do collagen-absorbable hemostat and absorbable gelatin film in this animal model.

Hypothyroidism is not commonly considered a complication of radiotherapy for head and neck cancer. A series of 96 patients treated with radiotherapy alone or combined with surgery for head and neck cancer was retrospectively studied. All patients had radiation ports that included the thyroid gland. Hypothyroidism after radiotherapy was documented in 26% of all patients. The majority of patients had subclinical hypothyroidism manifested by elevated thyroid-stimulating hormone (TSH) levels. The incidence of hypothyroidism dramatically increased to 65% when radiotherapy was combined with surgery that included a partial thyroidectomy. In addition, we report the unusual occurrence of massive head, neck, and hypopharyngeal edema caused by severe hypothyroidism in two patients. We advocate routine monitoring of head and neck cancer patients for hypothyroidism after radiotherapy involving the thyroid gland and recommend levothyroxine replacement therapy for subclinical hypothyroidism.

Adhesion of the tympanic membrane to the promontory may occur in chronic otitis media or in the postoperative ear. Silicone plastic sheets are commonly used to form a physical barrier to adhesion. These sheets are generally well tolerated, but they are subject to occasional extrusion, encapsulation, or foreign body reaction. The ideal barrier to adhesion formation would be a nonreactive, flexible, absorbable substance that would obviate long-term toxicity considerations. In this study polydioxanone sheets were compared with silicone plastic sheets in the middle ear of the Mongolian gerbil. The eustachian tube was cauterized to create severe tympanic membrane retraction. A fabricated sheet of polydioxanone was implanted in the middle ear of 30 Mongolian gerbils and compared with silicone plastic sheets implanted in another group of 30 animals. A sham operation was performed on the other ear to serve as a surgical control. Evaluation of the temporal bones at 5, 10, and 15 weeks showed no significant differences in the rate of adhesion formation, effusion formation, or polymorphonuclear infiltration by the Fisher exact test. There was histologic evidence that polydioxanone was still providing an effective barrier at 10 weeks. The results of this study demonstrate that polydioxanone sheets are as effective and as well tolerated as silicone plastic sheets in an animal model. Further study of polydioxanone in this role is warranted.

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