ACUTE OUTIS MEDIA 313 grey tinge above the line. Bubbles may also be visible through the drum- head, produced by the pressure of air in the fluid and may be seen immedi- ately after inflation of the middle ear. Catheterization produces differing sounds on auscultation, being unduly loud in some cases and in others producing an interrupted gurgling sound. If catheterization results in com- plete diffusion of fluid the membrane assumes a more normal colour, but in the presence of a thickened drumhead these changes may not be seen. Ejection of the condition may also be difficult when the tympanum is full of fluid. Then the membrane may have a darker colour than normal or a distinctly yellow tinge with a glistening appearance. In some cases the colour is bluish owing to the presence of blood in the effusion. The handle of the malleus is often sharply defined. In cases where the drumhead has a full or slightly bulging appearance with dilatation of the vessels radiating from the malleus and showing as red wavy lines on its surface (see Plate X, 4), an intermediate stage between acute non-purulent and acute purulent otitis media has developed. DIAGNOSIS. The diagnosis can generally be made on the otoscopic appear- ances particularly when a hairline or bubbles of air can be seen in the tympanum. Deafness _of conductive type, shown by tuning fork tests and confirmed by audiometry, is present. The pneumatic speculum used to determine mobility of the drumhead may also demonstrate movement of the hairline and air bubbles when they are present. In uncomplicated cases successful inflation disperses fluid, equalizes pressure within the tympanum to atmospheric pressure and restores hearing. PROGNOSIS. In recent cases and in those due to obstructive causes such as adenoids the prognosis is good provided that the causal condition is adequately treated. Recurrences lead to structural changes in the middle ear with a less favourable prognosis in regard to hearing. TREATMENT. Dramagejjf fluid from the middle ear firstly by the natural route., the Eustachian tube, may be assisted by the use of decongestant nasal drops such as ephedrine hydrochloride 1 per cent in normal saline, by steam inhalations containing menthol and by the administration of an ant i- Mstarnine^preparation especially where an allergic factor is present. During inhalations Valsalva's auto-inflation may be performed but successful infla- tion may require politzerization or Eustachian catheterization carried out daily. Failure of these measures with persisting deafness requires surgical treatment, which should result in the immediate return of normal hearing. Myringotomy is preferred to needle aspiration because of the latter's frequent failure. The procedure is usually performed under general anaes- thesia employing the operating microscope. A small stab incision in the antero-inferior quadrant of the membrane permits the entry of air into the middle ear and allows aspiration of the effusion. The myringotomy incision tends to heal rapidly so that an effort should be made to obtain total aspira- tion of fluid. In cases of persistent or recurring effusion myringotomy requires to be repeated and a small plastic tube, a grommet, is inserted. This provides further drainage and aeration of the middle ear. In most cases the grommet is self-extruded in a few weeks or months. If not, it may be removed either as an outpatient in adults or under anaesthesia in children.