Excluding the condition already described as connected with haematoma, the inflammations of the dura mater are, for the most part, secondary to affections of the bones or sinuses. In compound fractures of the skull, suppuration may extend to the dura mater, and in some cases to the soft membranes. Caries of the bones may have a similar result. Thrombophlebitis of the sinuses, especially in cases of disease of the ear, also gives rise to suppurative inflammation, sometimes associated with gangrene of the dura mater. (See under Abscess of the Brain).