Tympanic bulla pneumatization following experimental mastoidectomy in a porcine animal model

The effect of mastoidectomy on mastoid pneumatization was investigated in an animal model. Experimental mastoidectomy was performed on the air cell system of the tympanic bullae in 10 four-week-old piglets. The developmental process of this structure is very similar to that of the human mastoid air cell system. Two piglets each were decapitated at 1 and 2 weeks, and 1, 3 and 5 months after the operation, and hematoxylin and eosin sections of the bullae were examined histopathologically. The development of the tympanic bulla itself was not affected by the operation. However, inside the bulla, a great amount of bone tissue had proliferated peripheral to the surgical cavity without new formation of normal pneumatized cells. When mastoidectomy was performed in the course of the pneumatization, subsequent pneumatization did not occur in this animal model. This result suggests that mastoidectomy in childhood may arrest the new formation of mastoid air cells in humans.