Congenital contraction and closure of the canal have been observed in various degree.

Inflammations are similar to those of the skin, and may be either in the form of boils, which are somewhat frequent, or of a diffuse inflammation. The former have the characters of cutaneous boils, with which they may be associated; the latter result chiefly from injuries, but also from the acute exanthemata, chiefly small-pox, from erysipelas, and from ordinary skin eruptions. The disease may extend to the osseous wall of the canal and lead to caries or necrosis, but these are more frequently the consequences of affections of the middle ear. In more chronic cases/we have the usual new-formation of tissue of chronic inflammations, resulting in thickenings of the cutaneous lining of the canal, and also in some cases in hyperostosis, which may greatly contract the canal.

Exostoses not infrequently spring from the osseous wall.

Accumulations of cerumen very frequently occur to such an extent as to occlude the canal and cause deafness. They are usually dry and are composed of cerumen mixed with epidermis, hair, dust, etc. The accumulation is due either to excessive secretion or to some impediment to the escape of the wax.

Foreign bodies and Parasites are met with in the meatus. The former consist of a great variety of materials introduced from without and met with chiefly in children. Insects and their larvae are occasionally found in the ear, the latter chiefly in cases where purulent discharge exists. The acarus folliculorum also occurs.

Fungi belonging to the family of the Aspergillus have been frequently observed growing in the meatus, chiefly in its inner recesses and on the tympanic membrane. They cause obstruction of the canal and may give rise to serious inflammations.