MISCELLANEOUS AFFECTIONS OF THE SINUSES 85 Compound Fractures. These are treated on general surgical principles of cleaning the wound and removal of foreign bodies and bony spicules. Reconstruction is not undertaken in the presence of infection. It involves the correction of the bite and elevation of the bony walls of the antrum and fixation until union has occurred. Penetrating Wounds. Penetrating wounds involve the frontal and maxillary sinuses as a rule. Bullet wounds of the frontal sinus may involve the dura mater, while bullets entering the maxillary sinus may pass into the nose, the orbit or the pterygoid fossa depending on the trajectory. Surgical removal of the missile and bony fragments is undertaken with antibiotic cover. ORO-ANTRAL FISTULA An oro-antral fistula occurs most frequently through the alveolar border following dental extractions, particularly of upper molar teeth, but it may also follow a Caldwell-Luc operation in which the incision has broken down, or the spread of a malignant tumour of the maxillary sinus through the hard palate. Predisposing factors include a root abscess, a retained tooth root or a dental cyst. The early management of an oro-antral fistula following dental extraction is important. A small, clean fistula may be sutured immediately, and many fistulas heal provided that the blood clot in the lumen is un- disturbed and that antibiotics are given. In the larger fistula a temporary acrylic plate may be fitted to prevent food entering the fistula or infecting the suture line during healing. Should a tooth root have been forced into the antrum during extraction a Caldwell-Luc operation is performed, the tooth root removed and the incision and fistula are closed by sutures. Should the maxillary sinus have become infected before the patient is seen a radical antrostomy is performed. A large fistula which cannot be closed by direct suturing is repaired by sliding a palatal flap laterally to cover the defect and suturing it to the freshened buccal edge of the fistula. MUCOCELE A mucocele may arise, for no known reason, in the ethmoidal or frontal sinuses, and is characterized by the appearance and slow painless growth of a rounded swelling in the superomedial quadrant of the orbit, usually above the inner canthus. The affected sinus is distended and its bony walls are thinned. The orbital contents may be displaced forwards, downwards and laterally (Plate IV), and this causes diplopia. It is not uncommon that the swelling has been present for many months before advice is sought because enlargement is slow and painless. CLINICAL FEATURES. The characteristic swelling is obvious, and feels elastic. It is not tender and it cannot be reduced by pressure. The skin is freely movable over the swelling. The eyeball is limited in its movement medially and upwards; the pupil reacts to light and the fundus is normal. There is usually no abnormality on anterior rhinoscopy. Radiography will show the increased density and enlargement of the sinus. TREATMENT. The mucocele should be removed completely at an external fronto-ethmoidal operation, and there should be no recurrence. The cyst contains sterile green or brownish fluid.