Steps must be taken to prevent infection from the mucous surfaces implicated. This is exceedingly difficult in fractures opening into the pharynx and nose. Owing to the general condition of the patient, it is usually impossible to employ nasal douching or mouth washes, but spraying the cavities with peroxide of hydrogen or other antiseptics may be employed with benefit. In fractures of the middle fossa, the ear should be gently sponged out and the meatus plugged with gauze, retained in position by adhesive plaster or a bandage. When there is a persistent escape of blood or cerebro-spinal fluid, the dressing requires to be changed frequently. In compound fractures of the anterior fossa due to perforation through the orbit, the frontal bone should be trephined to admit of the removal of loose fragments or of any foreign body that may have entered the skull and to provide for drainage. CHAPTER XIV DISEASES OF THE BRAIN AND MEMBRANES Pyogenic diseases--Meningitis: _Varieties_--Abscess: _Varieties_--Sinus phlebitis--Intra-cranial tuberculosis. Cephaloceles--_Meningocele_--_Encephalocele_-- _Hydrencephalocele_--Traumatic cephal-hydrocele--Hydrocephalus; _Varieties_--Micrencephaly. Cerebral tumours. Tumours of the pituitary body. Epilepsy--Hernia cerebri. Surgical affections of cranial nerves--Cervical sympathetic. PYOGENIC DISEASES The most important intra-cranial conditions that result from infection with pyogenic bacteria are: meningitis, abscess of the brain, and phlebitis of the venous sinuses. The organisms most frequently associated with these conditions are the staphylococcus aureus and the streptococcus, but it is not uncommon to meet with mixed infections in which other bacteria are present--particularly the pneumococcus, the bacillus fœtidus, the bacillus coli, the bacillus pyocyaneus, and the diplococcus intracellularis. By far the most common source of intra-cranial infection is chronic suppuration of the middle ear and mastoid antrum, the organisms passing from these cavities to the interior of the skull directly through a perforation of the tegmen tympani or of the wall of the sigmoid groove, or being carried in the blood stream by the emissary veins. In some cases the infection travels along the sheaths of the facial and acoustic nerves. Less frequently infective conditions of the nasal cavity and its accessory air sinuses, and compound fractures of the skull, particularly punctured fractures, are followed by intra-cranial complications; or infection is conveyed to the inside of the skull, by way of the emissary veins, from wounds of the scalp, or from such conditions as erysipelas of the face and scalp, malignant pustule, carbuncles, or boils.