Fine Structure of the Rat Tympanic Membrane after Treatment with Local Anaesthetics

Abstract

The tympanic membrane of the rat was studied ultrastructurally after application of a local anaesthetic-lidocain spray. Already after 10 min, degenerative changes-or even necrosis-were observed on both epithelial surfaces of the eardrum. Later on, a marked hyperplasia of the epidermal layer was most characteristic, as was a proliferation of the fibroblasts of the subepithelial connective tissue. After 3 weeks the eardrum had not regained its normal appearance. No perforations were encountered and only minute substructural changes could be detected within the fibrous layer.

Key Words:

• Tympanic membrane
• fine structure
• lidocaine
• rat
• local application