The human ear consists of three components. These are the outer or external ear canal, the middle ear and the inner ear. They are interconnected serially and the ear drum is placed between the external ear canal and the middle ear. All three components are important for normal reception of sound and the main nerve that carries the sound impulses to the brain leads off from the inner ear. The middle ear contains a string of very small bones that link the ear drum to the inner ear. The middle ear is connected to the throat area by a tube called the Eustacian tube. This tube serves two purposes. It helps to drain out the normal secretions from the middle ear and it also helps to equalize the pressures of the middle ear and the outside environment. These processes are quite important to maintain the integrity of the middle ear and to facilitate the normal conduct of sounds through the middle ear. The inner ear also contains a mechanism for maintenance of posture.

In perception of sound, the ear works by receiving sound waves and sending messages to the brain. The outer ear includes the part of the ear one can see and the ear canal. The sound waves go through the ear canal and impinge on the eardrum and cause it to vibrate. The vibration of the eardrum leads to a process that makes the tiny bones in the middle ear to move. This movement sends the sound waves to the inner ear from where it is conducted to the brain by the auditory nerve.

All three components of the ear can get infected and cause some problems. By far, the commonest is infection of the middle ear. All over the world, ear infections occur in a considerable proportion of children and in the United States of America alone, it has been estimated that around ten million children a year suffer from ear infections. Although these problems are commonly seen in the Sri Lankan medical institutions, we have no accurate statistics of the exact magnitude of these infections.

The external or outer ear canal infections are uncommon and are usually caused by bacteria or fungi. There may be some pain in the ear but the predominant symptoms are those of ear irritation and blockage. There may be a discharge containing pus from the ear. These are easily treated with either systemic or local antibacterial and antifungal agents. These usually resolve without any undue long-term problems.

The more important types of ear infections involve the middle ear. Such infections could be caused by viruses or bacteria and are most common in children under the age of three because the Eustachian tube is so small and narrow. This makes it so much easier for it to get blocked, especially with colds and upper respiratory infections. The direction of the Eustachian tube in infants is more horizontal than vertical and this makes drainage difficult, making them more susceptible to middle ear infections. Fluid collects and blocks the tube and this will contribute to the growth of bacteria in the ear. However, most children outgrow ear infections as the structure and shape of their ear canal changes allowing fluids to drain easily. The childhood risks of getting middle ear infections are increased by exposure to cigarette smoke, history of previous ear problems, family history of ear infections, attending day-care centres, premature birth, frequent upper respiratory tract infections, taking a bottle to bed, use of soothers or pacifiers and susceptibility to upper respiratory tract allergies. Very often, middle ear infections are a complication of a cold or virus. The Eustachian tube becomes clogged with mucus and the pressure in the ear rises and the ear becomes infected. Acute otitis media is the medical term for the common middle ear infection. When caused by bacteria, middle ear infections tend to cause significant problems.

Middle ear infections present with fever and ear ache. In very young children and infants the child or baby may cry inconsolably and may pull and tug at the affected ear. They are quite irritable as well. If the infection is not adequately controlled in time, the pressure builds up within the middle ear and ultimately leads to rupture of the ear drum. Once that occurs, a discharge containing pus appears from the ear canal. Once the pressure is relieved by the rupture of the ear drum, the pain eases but the discharge becomes more prominent. If untreated or treated inadequately, the situation gets on to a chronic stage and becomes a persistent problem. Such situations do lead to defective hearing. In addition, the infection could spread to the adjoining bone and cause a chronic bone infection. This is quite difficult to treat and may need surgical drainage as well. Spread of the infection upwards leads to it being the cause of meningitis which is an infection of the coverings of the brain. This is a serious complication which needs urgent assessment and treatment. Rarely, the bugs spread into the blood stream and cause infections at remote sites. This too is a grave complication that needs urgent treatment.

Acute middle ear infections should only be diagnosed by a qualified doctor after looking into the ear with a special instrument known as the auroscope. It lights up the ear canal and allows visualisation of the ear drum. In acute infective states, the drum appears to be inflamed, red and some times bulging outwards. Movement of the drum too may be impaired. With air and fluid collections in the middle ear, gas bubbles too may be seen. Once a middle ear infection is diagnosed appropriate treatment should be instituted. These will consist of appropriate antibiotics and decongestant nose drops to reduce the upper respiratory congestion and open up clogged Eustacian tubes. These nose drops need to be used only for a limited period of time and it is not a good practice to use them for prolonged periods of time In acute otitis media, the child should feel a lot better with treatment within about 48 hours and if this is not the case, re-examination and re-thinking is needed on the part of the doctors treating the child. Anyhow, it is advisable for the child to be re-evaluated, even when the response is quite good, after a period of 7 to 10 days to ensure complete recovery.

In some instances fluid collects in the middle ear following an infection. This is known as otitis media with effusion and is commonly referred to as "glue ear" as well. This could lead to a feeling of fullness in the ear and reduction in the powers of hearing. Usually the fluid goes away with treatment in 2 to 3 months and hearing returns to normal. This condition, when it is prolonged and becomes troublesome, often requires the insertion of small plastic tubes known as grommets through the ear drum to equalize pressures and allow drainage. These devices also allow air into the middle ear so that fluid can drain out down the Eustachian tube. They’re inserted through the eardrum during surgery under anaesthesia and stay in place for an average of 6 to 9 months. The tubes are usually left in place until they fall out on their own or a doctor decides that the child no longer needs them. Middle ear infections and fluid in the ear are the most common causes of temporary hearing loss in children. Children who have ongoing problems with hearing may have trouble developing their speech and language skills. Repeated ear infections are known to cause scarring of the delicate tissues of the middle ear and lead to permanent hearing loss as well. If a child’s ears are always clogged and blocked while they are developing their speech, this will most likely result in slow speech and show up as problems with the development of learning. Thus, it is imperative that formal hearing tests are performed on children who have troublesome and niggling ear infections.

There are a couple of things which could be done to prevent middle ear infections. One is breast feeding. It has now been established that in addition to a multitude of other protective effects of breast milk, it specifically plays a role in preventing middle ear infections, especially during infancy. The other useful thing to do is to prevent children under the age of two years feeding from a bottle while lying flat on their backs. This could lead to some of the milk actually getting into the Eustachian tubes. In addition, some of the vaccines used in children such as the Haemophilus influenzae b or Hib vaccine and the pneumococcal vaccine, protect them against middle ear infections as a significant proportion of such infections are caused by these organisms. Children in day care centres tend to have more colds and a higher risk of ear infection. Although it would be best to keep an ill child at home, this may not always be possible. Parents should work with day care centre staff to ensure proper hand-washing, tissue use and cleanliness.

Infections of the inner ear too may cause problems in childhood. These are quite rare and are mostly due to viral infections. In addition to the sound conducting pathways, the inner ear also contains a specialised organ called the labrynth that is intimately concerned with the maintenance of position in space. Children affected by inner ear infections have ringing noises in the ear, show up with dizziness and in severely affected cases demonstrate a marked inability to maintain posture and not even be able to stand up straight. In the acute phase, some drugs could be used to mitigate these symptoms. Most of these viral infections are self-limiting and will resolve over a period of time without any undue long-term effects. These infections are quite uncommon and can be diagnosed only by a detailed evaluation.

The writer would appreciate some feed-back from the readers. Please e-mail him at bjcp@sltnet.lk or write to him at the following address :-

Dr, B.J.C.Perera, Consultant Paediatrician, Asiri Medical Hospital, 181, Kirula Road,
Colombo 5.