Mastoid abscess
Mastoiditis is an inflammatory process of the mastoid air cells in the temporal
bone. In some patients, the infection spreads beyond the mucosa of the middle
ear cleft, and osteitis in the mastoid air-cell system or periosteitis of the
mastoid process develops, either directly by means of bone erosion through the
cortex or indirectly via the emissary vein of the mastoid.