It is an acute inflammation of middle ear by pyogenic organisms. Here, middle ear implies middle ear cleft, i.e. eustachian tube, middle ear, attic, aditus, antrum and mastoid air cells.
AETIOLOGY
It is more common expecially in infants and children of lower socioeconomic group. Typically, the disease follows viral infection of upper respiratory tract but soon the pyogenic organisms invade the middle ear.
ROUTES OF INFECTION
Via eustachian tube : It is the most common route. Infection travels via the lumen of the tube or along subepithelial peritubal lymphatics. Eustachian tube in infants and young children is shorter, wider and more horizontal and thus may account for higher incidence of infections in this age group. Breast or bottle feeding in a young infant in horizontal position may force fluids through the tube into the middle ear and hence the need to keep the infant propped up with head a little higher. Swimming and diving can also force water through the tube into the middle ear.
Via external ear : Traumatic perforations of tympanic membrane due to any cause open a route to middle ear infection.
Blood-borne : This is an uncommon route.
PREDISPOSING FACTORS
Anything that interferes with normal functioning of eustachian tube predisposes to middle ear infection. It could be:
□ Recurrent attacks of common cold, upper respiratory tract infections, and exanthematous fevers like measles, diphtheria, whooping cough.
□ Infections of tonsils and adenoids.
□ Chronic rhinitis and sinusitis.
□ Nasal allergy.
□ Tumours of nasopharynx, packing nose or nasopharynx for epistaxis.
□ Cleft palate.
Bacteriology : Most common organisms in infants and young children are Streptococcus pneumonia (30%), Hsaemophilus influenzae (20%) and Morexella catarrhalis (12%). Other organisms include streptococcus pyogenes, staphylococcus aureus and sometimes pseudomas aeroginosa. In about 18-20%, no growth is seen. Many of the strains of H. influenzae and Morexella catarrhalis are b-lactamase producing.
PATHOLOGY AND CLINICAL FEATURES
The diseases runs through the following stages:
□ Stage of tubal occlusion
□ Stage of pre-suppuration
□ Stage of suppuration
□ Stage of resolution or complication
Stage of tubal occlusion : Oedema and hyperaemia of nasopharyngeal end of eustachian tube blocks the tube, leading to absorption of air and negative intratympanic pressure. There is retraction of tympanic membrane with some degree of effusion in the middle ear but fluid may not be clinically appreciable.
Symptoms. Deafness and earache are the two symptoms but they are not marked. There is generally no fever.
Signs. Tympanic membrane is retracted with handle of malleus assuming a more horizontal position, prominence of lateral process of malleus and loss of light reflex. Tuning fork tests show conductive deafness.
Stage of pre-suppuration : If tubal occlusion is prolonged, pyogenic organisms invade tympanic cavity causing hyperaemia of its lining. Inflammatory exudate appears in the middle ear. Tympanic membrane becomes congested.
Symptoms. There is marked earache which may disturb sleep and is of throbbing nature. Deafness and tinnitus are also present, but complained only by adults. Usually, child runs high degree of fever and is restless.
Signs. To begin with, there is congestion of pars tensa. Leash of blood vessels appear along the handle of malleus and at the periphery of tympanic membrane imparting it a cart-wheel appearance. Later, whole of tympanic membrane including pars flaccida becomes uniformly red.
Tuning fork tests will again show conductive type of hearing loss.
Stage of suppuration : This is marked by formation of pus in the middle ear and to some extent in mastoid air cells. Tympanic membrane starts bulging to the point of rupture.
Symptoms. Earache becomes excruciating. Deafness increases, child may run fever of 102-103°F. This may be accompanied by vomiting and even convulsions.
Signs. Tympanic membrane appears red and bulging with loss of landmarks. Handle of malleus may be engulfed by the swollen and protruding tympanic membrane and may not be discernible. A yellow spot may be seen on the tympanic membrane where rupture is imminent. In pre-antibiotic era, one could see a nipplelike protrusion of tympanic membrane with a yellow spot on its summit. Tenderness may be elicited over the mastoid antrum.
X-rays of mastoid will show clouding of air cells because of exudate.
Stage of resolution : The tympanic membrane ruptures with release of pus and subsidence of symptoms. Inflammatory process begins to resolve. If proper treatment is started early or if the infection was mild, resolution may start even without rupture of tympanic membrane.
Symptoms. With evacuation of pus, earache is relieved, fever comes down and child feels better.
Signs. External auditory canal may contain blood tinged discharge which later becomes mucopurulent. Usually, a small perforation is seen in antero-inferior quadrant of septum. Hyperaemia of tympanic membrane begins to subside with return to normal colour and landmarks.
Stage of complication : If virulence of organism is high or resistance of patient poor, resolution may not take place and disease spreads beyond the confines of middle ear. It may lead to acute mastoiditis, subperiosteal abscess, facial paralysis, labyrinthitis, petrositis, extradural abscess, meningitis, brain abscess or lateral sinus thrombophlebitis.
TREATMENT
Antibacterial therapy : It is indicated in all cases with fever and severe earache. As the most common organisms are Strept. pneumoniae and H. influenzae, the drugs which are effective in acute otitis media are ampicillin (50 mg/kg/day in 4 divided doses), amoxicillin (40 mg/kg/day in 3 divided doses). Those allergic to these penicillins can be given cefaclor, co-trimoxazole or erythromycin. In cases where beta-Iactamase-producing H. influenzae or Moraxella catarrhalis are isolated, antibiotics like amoxicillin-clavulanate, augmentin, cefuroxime axetil or cefixime may be used. Antibacterial therapy must be continued for a minimum of 10 days, till tympanic membrane regains normal appearance and hearing returns to normal. Early discontinuance of therapy with relief of earache and fever, or therapy given in inadequate doses may lead to secretory otitis media and residual hearling loss.
Decongenstant nasal drops : Ephedrine nose drops (1% in adults and 0.5% in children) or oxymetazoline (Nasivion) or xylometazoline (Otrivin) should be used to relieve eustachian tube oedema and promote ventilation of middle ear.
Oral nasal decongestants : Psudoephedrine (Sudafed) 30 mg twice daily or a combination of decongestant and antihistaminic (Triominic) may achieve drops which are difficult to administer in children.
Analgesics and antipyretics : Paracetamol helps to relieve pain and bring down temperature.
Ear Cleaning : If there is discharge in the ear, it is dry-mopped with sterile cotton buds and a wick moistened with antibiotic may be inserted.
Dry local heat: It helps to relieve pain.
Myringotomy : It is incising the drum to evacuate pus and is indicated when (a) drum is bulging and there is acute pain, (b) there is an incomplete resolution despite antibiotics when drum remains full with persistent conductive deafness, (c) there is persistent effusion beyond 12 weeks.
All cases of acute suppurative otitis media should be carefully followed till drum membrane returns to its normal appearance and conductive deafness disappears.