Effect of middle ear infection on pneumatization and growth of the mastoid process. An experimental study in pigs.

The intention of this experiment was to investigate whether anatomical variations of the temporal bone such as low middle fossa dura, anterior position of the sigmoid sinus or small mastoid process, which are often seen at surgery in cholesteatoma patients, are caused by inflammation in early childhood. In 7 pigs, 1.5 ml paraffin liquid were instilled into the left tympanic cavity 2 or 7 days after birth in order to produce inflammation of the middle ear and tubal dysfunction. After six and a half months the length and area of the mastoid process were significantly smaller on the left instilled side than on the right, normal side. In all cases there was remarkable hypocellularity and increased thickness of the cortical bone strongly supporting the environmental theory of pneumatization that inflammation suppresses the pneumatization process and growth of the mastoid process.