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What is glue ear?
Glue ear is a condition where there is a build up of fluid in the middle ear. Other names for it include serous or secretory otitis media (SOM), otitis media with effusion (OME), catarrhal or non-suppurative otitis media.
How common is it?
It is the commonest cause of hearing loss in childhood, with up to 50% of all children having an episode at some stage. The prevalence, that is the number of affected individuals at a particular point in time, depends on age but in children aged 2 to 7 years of age is about 20%.
What is the middle ear?
The ear consists of three parts. The outer ear includes the pinna ( the floppy part attached to the side of the head) and the outer ear canal. The middle ear is the space between the eardrum and the inner ear. It contains the three little bones of hearing, the ossicles. Sound energy comes down the ear canal and vibrates the eardrum which then vibrates the bones of hearing, and in this manner the sound energy is transmitted to the inner ear. The workings of the inner ear are complex but in essence the cochlea converts sound energy to electrical energy which is conducted along the hearing nerve to the brain where it is recognized as sound.
What happens in glue ear?
The middle ear is normally full of air. It is connected to the area at the back of the nose, the postnasal space, by a tube, the Eustachian tube. This tube is normally closed at rest, but opens when we yawn or swallow. With time, the air in the middle ear is slowly absorbed by the lining of the middle ear, producing a low pressure. The air pressure at the back of the nose is the same as the air pressure outside. Normally, every time we swallow or yawn, the Eustachian tube opens and air flows from the back of the nose to the middle ear to equalize the pressure in the middle ear with the atmospheric pressure outside.
If something stops the Eustachian tube opening, the pressure in the middle ear cannot equalize, and continues to become more and more negative. Initially this sucks in the eardrum, but later fluid leaks out of the lining of the middle ear and fills the middle ear. The fluid is thin to start with but over time becomes thick and tenacious like glue, hence the term glue ear.
What causes glue ear?
There are many factors which may influence opening of the tube. A cold or other infection of the nose and back of the nose ( postnasal space) can cause swelling of the lining around the Eustachian tube opening, preventing it from opening. Glue ear is commoner in children who have a lot of contact with other children, for example at playgroup, and this is thought to be related to catching infections from other children. Glue ear is also commoner in the winter months, again probably related to infection.
Allergy and rhinitis (inflammation of the lining of the nose) can also cause inflammation and swelling of the opening of the Eustachian tube and interfere with its normal function.
In children, the shape and position of the Eustachian tube is different to that in adults, and it does not function very well, leading to glue ear, but as children get older the shape and position changes, and the tube starts to work better, so they become less likely to develop glue ear. In children with other problems such as cleft palate or Down’s syndrome, the muscles which normally open the Eustachian tube do not work very well so again these children are likely to have glue ear.
Swellings at the back of the nose, such as enlarged adenoids, may press on the opening of the tube and prevent it opening. Adenoids are often enlarged in children aged between two and five years, but after this age the head gets bigger more quickly than the adenoids so these get relatively smaller and often become less of a problem.
Glue ear may also be associated with passive smoking. It should be mentioned that many of these theories sound plausible but direct evidence to support them is limited.
In adults, tumours in the postnasal space can press on the Eustachian tube opening causing glue ear, although this usually only occurs in one ear. Pressure changes such as those that occur while flying can lead to barotrauma and fluid in the middle ear.
What problems does glue ear cause?
A middle ear which is full of fluid is a rich breeding ground for infecting organisms such as bacteria and so children with glue ear are likely to have a lot of acute ear infections, with pain and fever and feeling unwell. Of course, ear infections will make the lining of the middle ear and Eustachian tube more swollen so the fluid cannot drain out of the middle ear and air cannot get in, and so glue ear persists.
If the middle ear is full of fluid, the eardrum cannot vibrate, and so sound cannot be conducted from the outer ear to the inner ear, and the child cannot hear very well. It is common for children to have periods of glue ear and decreased hearing, especially after a cold. If this hearing loss is only present for a short period of time it is unlikely to cause long term problems, but if the hearing loss persists it will interfere with learning, speech and language development. Unfortunately, glue ear is commonest in children aged between two and five years, and this is a critical period for acquiring speech and language skills.
If a child cannot hear well and therefore does not respond to questions or instructions, his parents or teachers may think this is deliberate. Also, if the child cannot hear or communicate well, he may get upset and actually become badly behaved.
Glue ear can also affect the balance system and some young children with glue ear are noted to be clumsy or slightly off balance by their parents.
What are the complications of glue ear?
The eardrum (tympanic membrane) can be damaged by glue ear. An acute middle ear infection may burst through the eardrum, discharging the pus in the middle ear, relieving the pain and allowing the infection to settle. This is one of the natural ways an acute middle ear infection settles, and usually the hole in the eardrum (perforation) heals by itself. Occasionally it may not heal and the eardrum is left with a permanent hole, which can lead to recurrent ear infections and hearing loss.
With longstanding glue ear, after recurrent infections and perforations or after surgery for glue ear, the eardrum may become scarred with chalky patches developing in it (tympanosclerosis) This does not usually cause much in the way of problems unless the tympanosclerosis is very widespread, in which case the eardrum is very stiff and immobile, leading to hearing loss. It is more likely that an inexperienced observer may see the white patches and not recognize them as being fairly harmless and become unduly concerned.
When glue ear is longstanding, the eardrum become thin and weak, either due to enzymes in the glue itself or due to recurrent infections. A weakened and thin (atelectatic) ear drum may become more and more sucked in, forming a little pouch (retraction pocket). Even if the glue disappears, a retraction pocket can cause problems. It may become so sucked in that it sticks to the little bones of hearing in the middle ear, the ossicles, and eventually erodes these, causing a permanent hearing loss. The retracted pouch may become stuck to the medial wall of the middle ear, and this case the eardrum will not be able to vibrate and there will be a hearing loss. The pouch may also fill up with dead skin which can get infected and produce a discharge from the ear (a cholesteatoma). A cholesteatoma can lead to serious complications and usually requires surgery to make the ear safe.
How do I know if my child has glue ear?
The commonest symptoms are hearing loss which may come and go, recurrent ear infections, delayed speech and language development, and poor attention or misbehaviour. Young children may pull at the ear, while older children may ask for questions to be repeated or turn the television up loud. Poor balance or a discharging ear due to a perforation, retraction pocket or cholesteatoma are less common. If you suspect your child has glue ear then you should consult your general practitioner.
What will my general practitioner do?
Your general practitioner will ask questions about the problems described above and examine the patient, with particular attention to the ears. This is done using an instrument called an otoscope which shines a light into the ear canal and allows the eardrum to be seen. There may be wax in the way so the eardrum is not visible, and it takes a lot of practice to recognize the changes in the eardrum due to glue ear. The patients hearing levels also need to be measured. Not all medical practitioners have the equipment to measure hearing levels, the surgery may be noisy so the measurements may not be accurate, there may be wax in the way, and young children need special hearing tests which require a lot of time and expertise. For all these reasons, it may not be possible for your general practitioner to reach an accurate diagnosis, so he or she may refer you to the ear, nose and throat (ENT) department locally.
What happens in the ENT clinic?
The ENT specialist will again ask some questions and examine the patient. If there is wax in the ears, this can be removed. The eardrum can be examined using an otoscope, or if necessary a microscope which allows examination in more detail. Obviously the middle ear cannot be seen directly because the eardrum is in the way, so deciding whether there is fluid in the middle ear can be difficult. The eardrum may be sucked in (retracted), it may be dull or have a slightly golden colour due to the fluid in the middle ear, there may be bubbles visible behind the eardrum, or there may be other features such as a retraction pocket or an acute infection.
The patient will also need to have a hearing test in a sound proofed booth. Tones are played at different loudness levels in each ear through headphones and the patients is asked to press a button when he hears a noise. In this way the hearing levels for each ear can be determined. Small children cannot be tested this way, and need special children’s hearing tests.
The movement of the eardrum can also be assessed using an instrument called a tympanometer. A small probe is put in the outer ear canal, sounds are played through it and the reflected sound from the eardrum measured at different pressures. When there is fluid in the middle ear, the eardrum does not move and this can be detected by the tympanometer.
By putting together the results of these investigations the specialist can decide whether glue ear is present or not.
Does glue ear need treatment?
The majority of cases of glue ear resolve spontaneously. As a rough guide, if one hundred children have glue ear, 50% of these, that is 50, will be better within 3 months. Of the remaining 50, another 50%, that is 25, will be better after another three months, and so on. Although most cases of glue ear will resolve without treatment, there will be a few that linger on for months or years, and there are unfortunately a very small number of patients who are destined to have problems with glue ear into adult life.
Does this matter? If hearing is impaired at a critical age when speech and language are developing, these may be delayed which is undesirable. Hearing loss may interfere with learning at school and educational achievement. Recurrent ear infections are obviously uncomfortable and distressing, may lead to time off school, may lead to a damaged eardrum, and in rare cases may . Glue ear may cause only a minor hearing loss but lead to slow thinning of the eardrum and rotting of the ossicles and thereby produce long term damage. These are all serious consequences, and although it is true that most cases resolve without treatment, it is not possible to predict which cases will resolve and which will not. For this reason, most ENT specialists will assess the patient initially to confirm the presence of glue ear, but will usually review the patient in 3 or 4 months time and reassess to see if glue ear is still present before deciding on treatment. If hearing loss is persistent and there is evidence of impaired speech, language, learning or behaviour then treatment is indicated. If hearing in only one ear is affected, and hearing in the other ear is normal, then treatment is not indicated, unless there is evidence of damage to the eardrum or bones of hearing, or the affected ear gets recurrent infections.
What treatment is available?
Broadly speaking, treatment can be divided into medical and surgical.
Medical treatment includes the use of long term low dose antibiotics. Trimethoprim or Amoxycillin in a low dose e.g. 2 milligrams per kilogram bodyweight may given once a day for 6 to 12 weeks. The reasoning behind this is that repeated infections or a chronic infection may produce swelling of the Eustachian tube lining, preventing it from opening and draining and ventilating the middle ear, and so the glue ear cannot resolve. Antibiotics may break this vicious circle and allow the swelling to settle, thereby allowing air into the middle ear again.
Decongestants such as Sudafed should allow any swelling inside the nose and at the back of the nose to settle, helping the Eustachian tube to open, but unfortunately the results are not as good as one might expect, and even when there is a response it is usually short lived. Decongestants applied locally to the nose in the form of nose drops e.g. Ephedrine nose drops may be more effective, but can only be used for short periods at a time otherwise they may cause irreversible damage to the lining of the nose.
Patients with swelling of the lining at the back of the nose due to rhinitis may benefit from treatment of the rhinitis with a nasal steroid spray.
The Otovent nasal balloon is a small balloon on a nozzle which is inserted in one nostril, the other nostril is closed and the patient tries to blow up the balloon through his nose. This produces high pressures at the back of the nose and forces air up the Eustachian tube into the middle ear. Not all patients are able to do this but in those that can, the nasal balloon is effective in the short term.
Other medical treatments such as steroids or complementary medicine therapies have little evidence to support them.
A hearing aid can be used to overcome the hearing loss, but this will do nothing to prevent recurrent ear infections or drain the fluid and prevent further complications such as weakening the eardrum or rotting away of the ossicles.
What are the surgical options?
Surgical treatment consists of insertion of ventilation tubes, removal of the adenoids (adenoidectomy) or a combination of these. The adenoids may be enlarged and pressing on the opening of the Eustachian tube, or may be acting as a focus of infection.
Adenoidectomy is an operation usually performed under a general anaesthetic. There is always a slight risk of a reaction or something going wrong during a general anaesthetic but the risk in someone who is generally fit and well is very small. The patient is put to sleep, a gag is used to hold the mouth open, and the adenoids, which are located in the postnasal space at the back of the nose, are removed. They can be cut out with a curette, pressure and a pack is used to control the bleeding, and then the pack is removed. Sometimes the bleeding may persist despite all the surgeon’s efforts to control it, and in such cases it may be necessary to leave a pack in the postnasal space to control the bleeding. An alternative technique is to use diathermy to remove the adenoids, which results in bleeding areas being cauterised during the operation, but with either technique, there is a small risk of bleeding once the patient has left the operating theatre and returned to the ward. The patient will usually stay in hospital overnight and go home the next day. Adenoidectomy, especially when performed in conjunction with insertion of ventilation tubes, is an effective treatment for glue ear, but in view of the possible problems described above, is often not used on the first occasion. Surgical treatment usually consists of insertion of ventilation tubes initially, but if the glue ear recurs and further surgical treatment is necessary, then removing the adenoids at the same time as inserting more ventilation tubes is often beneficial. In patients where the main complaint is of recurrent ear infections, then the likely source of the infections may well be the adenoids, and these should be removed first. If the recurrent ear infections are felt to be due to recurrent tonsil infections then the tonsils may also need to be removed.
Ventilation tubes:
Sometimes, when a hole is made in the eardrum, no fluid is found! This may be because the fluid had disappeared by itself before surgery, but this was difficult to tell just by examining the ears before surgery. Sometimes the fluid may be driven out by the gases used for the anaesthetic. The surgeon may warn the patient or parents beforehand that no fluid may be found, and in this case insertion of grommets may not be necessary.
More detail:
Glue ear is the commonly used term for a non-purulent collection of fluid in the middle ear, although the terms middle ear effusion or otitis media with effusion (OME) are more acceptable in the medical literature. Other terms used to describe this condition include catarrhal, seromucinous, secretory and exudative otitis media.
Incidence:
It is the commonest cause of hearing loss in childhood. The incidence, that is the number of new cases per year depends on the age of the population under consideration, and has been reported as about 42% in three year old children (Maw 1997). Prevalence, that is the number of affected individuals at a particular point in time, depends on age but in children aged 2 to 7 years of age is of the order of 20% ( Haggard and Hughes 1991).
Aetiology:
The main aetiological factors are thought to be Eustachian tube dysfunction, infection or a combination of these factors.Eustachian tube dysfunction may be due to palatal defects such as cleft palate, where the pull of the tensor palati muscle is deficient and this is thought to result in impaired eustachian tube opening. Glue ear is almost invariably present in such cases (Grant et al 1988), and there is some evidence of improvement in glue ear following cleft palate repair. Ciliary dysfunction such as that seen in Kartagener’s syndrome is associated with glue ear, and impairment of ciliary function by tobacco smoke may be one reason why passive smoking is associated with glue ear.
Although the effusion in glue ear is non-suppurative, glue ear often follows on from an episode of acute otitis media, and positive bacterial cultures have been demonstrated in up to 50% of cases of middle ear effusion. The organisms isolated are the same as those isolated from acute middle ear infections, namely Streptococcus pneumoniae, Haemophilus influenzae, Moxarella catarrhalis and Streptococcus pyogenes. The eustachian tube in children is shorter and more horizontal than in adults, and it is possible this configuration is more conducive to ascending infection leading to glue ear, which may explain why as the tube adopts a more adult configuration by the age of 7 the prevalence of glue ear decreases.
It has been demonstrated that the adenoid enlarges more rapidly than the nasopharynx between the age of 3 and 5 years (Jeans et al 1981), leading to nasopharyngeal obstruction. A simplistic view is that enlarged adenoids may directly impinge on the eustachian tube orifice, although the effect on eustachian tube function may be related to altered nasal and oral breathing patterns secondary to the nasopharyngeal obstruction. The adenoids may also be responsible for ascending infection leading to glue ear.
Other factors implicated include race, with Eskimos and American Indians being more commonly affected than Caucasians. Poor living conditions and pollution have been implicated (Harvey 1975), as has passive smoking (Strachan et al 1988). Breast feeding may have a small protective effect.
Pathophysiology:
Two main mechanisms are postulated for the persistent presence of middle ear fluid. The vacuum theory assumes that a prolonged negative middle ear pressure leads to a transudate of fluid from the mucosal lining of the middle ear. Middle ear gases are absorbed by the middle ear mucosa producing a negative middle ear pressure, and in the presence of impaired eustachian tube opening, the pressure cannot be equalised with external atmospheric pressure. In the presence of middle ear infection, the middle ear mucosa may be hyperaemic and absorption of middle ear gases may be increased.
An alternative theory proposes that subacute middle ear infection may produce an exudates of fluid into the middle ear. Infection may also cause oedema of middle ear and eustachian tube mucosa leading to obstruction of the eustachian tube and hence impaired drainage of the middle ear fluid. Both theories may be partially correct.
Natural history:
An understanding of the natural history of glue ear is crucial to understanding the indications for intervention. Persistent middle ear effusion following acute otitis media, whether viral or bacterial, is very common but the majority resolve within 6 weeks. A study on preschool children with glue ear demonstrated approximately 50% improved in every 3 months (Zielhuis et al 1990), with only about 5% of effusions lasting more than one year. The implication is that if left alone, the majority of effusions will clear without treatment. However, the concern of otolaryngologists and of parents is that there is no way to accurately predict which children will improve spontaneously and which will eventually require intervention. In the meantime, while waiting for spontaneous resolution, there may be impairment of education and speech and language development, behavioural problems, and complications of glue ear such as recurrent attacks of acute otitis media or permanent damage to the tympanic membrane or ossicles. The difficulty is determining the optimal time to wait before starting treatment so as to minimise unnecessary interventions but also to minimise complications of untreated glue ear.
Presentation:
The commonest presentation is with fluctuating or constant conductive hearing loss. Babies may pull at the affected ear or ears. Young children may complain that they cannot hear, but often the parents notice that their children ask for things to be repeated, say “Eh?” or “What?” a lot and have the television volume turned up. Delayed speech and language acquisition or unclear pronunciation may be noticed. There may be complaints of inattention or behavioural problems at school. These features are a direct result of the middle ear effusion on hearing.
Other effects of glue ear include imbalance although the exact mechanism is unclear. It is not uncommon for parents to admit on direct questioning that their toddlers with glue ear seem to be clumsy or are slow walking. A common presentation of glue ear is with recurrent episodes of acute otitis media, which at times lead to perforation of the tympanic membrane with discharge of pus and relief of symptoms. The majority of these perforations heal spontaneously within a few weeks but on occasion the perforation may become persistent. Recurrent episodes of acute otitis media cause pain, fever and malaise, but in addition can lead to more serious consequences such as suppurative labyrinthitis if the infection spreads to the inner ear or intracranial complications including meningitis and cerebral abscess if the infection spreads in that direction. The tympanic membrane may become thin and atelectatic due to loss of the fibrous middle layer, either due to enzymes in the middle ear effusion or as a result of recurrent middle ear infection. Atelectatic tympanic membranes may become retracted and adherent to the ossicles, and this may in turn lead to necrosis of the ossicles with a permanent conductive hearing loss, which will require a hearing aid or surgical reconstruction to correct. Ossicular erosion may also be related to recurrent acute otitis media. Atelectatic tympanic membranes may also lead to the formation of retraction pockets and cholesteatoma, a collection of squamous epithelium within the middle ear, which in most cases will require surgery to make the ear safe. These complications of glue ear are infrequent but can have serious consequences.
Diagnosis:
This is usually made on the basis of the symptoms as described above and some additional tests. Otoscopic examination of the ears may demonstrate a retracted, dull tympanic membrane, a golden appearance due to the middle ear fluid or perhaps bubbles visible behind the tympanic membrane, but interpretation of the appearance is not always straightforward, and even experienced observers may only be correct 75% of the time. Examination under a microscope in clinic is more helpful. Tympanometry can be used to assess the mobility of the tympanic membrane, with a flat trace suggesting fluid in the middle ear causing immobility of the tympanic membrane. Hearing tests such as pure tone audiometry or play audiometry in younger children give an indication of the severity of any hearing loss. All these factors are taken into consideration when determining if glue ear is present and if treatment should be instituted. However, the most accurate way of determining if fluid is present in the middle ear is to make a small hole in the tympanic membrane (a myringotomy) under a general anaesthetic. Trials have shown that in between 10 to 30% of cases where glue ear has been diagnosed, no fluid is found in the middle ear! This may reflect incorrect diagnosis, but in some cases the anaesthetic gases used may drive the fluid out of the middle ear. In any case, it is important to reassess the patient prior to surgical treatment for glue ear to make sure the fluid has not resolved spontaneously while waiting for treatment.
Results of treatment:’
Autoinflation- A meta-analysis of the studies regarding use of autoinflation balloons for glue ear suggests there may be some benefit but this is likely to be short lived (Reidpath et al 1999)
Glue ear has been reported as one of the commonest causes of vestibular dysfunction in children, and this vestibular dysfunction can be improved by insertion of ventilation tubes (Grolz et al 1991, Grace et al 1990).
Insertion of ventilation tubes has been shown to significantly reduce behavioural problems in children with glue ear as opposed to a wait and see policy (Wilks et al 2000).
Combined adenoidectomy and insertion of ventilation tubes is more effective than either treatment alone (Maw et al 1993)
Ventilation tubes improve verbal comprehension and expressive language skills as compared to watchful waiting (Maw et al 1999)
One study (Hellier et al 1997) found grommet insertion produced improvement in hearing (92.1%), a reduced frequency of ear infections (74.1%), a reduction in postoperative GP visits (87%), less time missed from school (70.7%), as well as a variety of improvements in children's speech, education and general behaviour. Overall, 96.7% of parents were satisfied that the decision to insert grommets in their child was correct
Treatment options: When considering treatment options, the natural history, that is the tendency for spontaneous resolution of glue ear needs to be remembered.
Medical: Medical treatment options are generally unsatisfactory and of limited benefit.
There is little evidence to support the use of decongestants, especially in the oral form. Topical decongestants in the form of nasal drops and sprays may be of benefit where there is oedema of the mucosal lining of the nose and nasopharynx interfering with Eustachian tube function, although the evidence for this is limited. The most common medical treatments used by ENT specialists are long term antibiotics and autoinflation devices. Short term use of antibiotics, for example for one to two weeks, is not felt to be of great benefit, although some studies have reported a short term improvement in persistent effusions with the use of co-amoxiclav compared to placebo (Van Balen et al, 1996). Most ENT specialists prefer to use a six to twelve week course of Amoxycillin or Trimethoprim at a low dose such as 2 mg per kilogram bodyweight, and some studies (Mandel et al 1996) have shown an improvement with Amoxycillin compared to placebo. Significant side effects are unlikely with such low doses but can occur, and widespread use of antibiotics may lead to the development of resistant organisms. Low dose long term antibiotics may indeed help to prevent recurrent ear infections and aid resolution of a chronic low grade infection, but the improvement seen may just be due to the natural history of glue ear. A meta-analysis of the available evidence (Williams et al 1994) concluded that antibiotics have a limited short term beneficial effect on glue ear, but no long term benefit has been demonstrated. The main role of long term antibiotics may be in those cases where parents are reluctant to consider surgical intervention but would like to try something.
There is no evidence to support the use of antihistamines for glue ear.
Some reports have suggested a limited improvement with steroids (Rosenfeld 1995),but there is no convincing evidence to support the use of steroids in glue ear, especially when the adverse side effects of steroids are considered.
Treatment of associated allergy ant rhinitis mat be of benefit (Scadding et al 1993)
Surgery
The simplest form of surgery is to make an opening into the middle ear through the tympanic membrane, a myringotomy, and aspirate the middle ear fluid. When the fluid is thick and glue like, this may be difficult. In addition, the hole created in the tympanic membrane is likely to heal very quickly, usually within a week or two, and the middle ear effusion is likely to recur. For this reason, myringotomy is usually accompanied by insertion of a ventilation tube.
Ventilation tubes:
Grommets- The most familiar ventilation tube in the UK is a grommet, of which there are different makes, such as Shah or Shepard grommets. The variations between the different types are relatively small, and selection of which grommet to use is often determined by the surgeon’s preference. The basic design is of a small plastic tube with a hole in the middle which sits in the tympanic membrane, providing a passage for air to enter the middle ear space from the outside. The grommet is held in place by flanges which lie on either side of the tympanic membrane. The flanges may be elongated in certain areas to allow easier insertion of the grommet. Different sizes are available, such as the “baby Shah grommet” for use in narrow ear canals.
These grommets are designed to be extruded by the natural forces from the epithelium of the tympanic membrane, and most grommets extrude between nine and eighteen months after insertion. The hope is that by the time the grommet extrudes, Eustachian tube function will have improved and the glue ear will not recur. However, there is no guarantee of this, and up to 30% of patients may require further insertion of grommets, or even multiple re-insertions. Insertion of grommets is a manoeuvre to buy time while waiting for spontaneous improvement of middle ear ventilation; it is not a cure for the underlying cause.
Technique: Grommet insertion in children is performed under a general anaesthetic, although insertion under local anaesthesia is possible in adults. Local anaesthesia may be achieved by application of an anaesthetic compound such as Emla cream directly onto the tympanic membrane and leaving this in place for approximately one hour before removing it. An alternative is to inject local anaesthetic solution such as 1% Lignocaine into the skin of the ear canal and behind the ear canal. Once the patient is anaesthetised, the ear is examined using a microscope, and any obstructing wax or debris is removed. An incision is made in the tympanic membrane using a sharp knife. It is recommended that a radial incision is made in the anterior and inferior area of the tympanic membrane as this carries the least risk of damage to the middle ear structures. As much middle ear fluid as possible is aspirated using suction, although it can be difficult to remove thick glue like material. The grommet is grasped using crocodile forceps and partially inserted through the incision, then manipulated using a curved needle until it sits securely with the flanges on either side of the tympanic membrane. An improvement in hearing is often noticed immediately in the post operative period, although it may take a few weeks for any remaining middle ear fluid to resolve. The patient is allowed to go home the same day provided there are no problems, and followed up in the outpatient clinic.
Problems:
Any general anaesthetic carries a risk of a reaction or problem during the anaesthetic, but this risk is very small with modern anaesthetics. The risk of a serious problem from an anaesthetic in a fit patient is estimated at about one in 80,000. During surgery, problems may be experienced if the ear canal is very narrow, and it may be difficult to insert a grommet, even a small baby Shah grommet. It is possible to damage the ossicles or other middle ear structures during surgery but this is unlikely in the hands of a competent surgeon. The grommet may be pushed too far and fall into the middle ear. It can be removed by elevating the tympanic membrane for access, but it can also be safely left in the middle ear and there no reports of problems caused by leaving the grommet in the middle ear. The grommet may become blocked by dried blood but this usually clears spontaneously.
Post operatively, the grommet may become infected leading to discharge. However, discharge is usually due to middle ear infection, either due to organisms ascending via the Eustachian tube or gaining access to the middle ear via the grommet. Reported rates of discharge following grommet insertion vary from 12% to 64% (Pringle 1993). Occasionally the grommet may become infected and cause persistent discharge and removal may be required in such cases. Traditionally it has been believed that swimming with grommets in place results in water leaking through the grommet into middle ear causing infection and discharge, and the advice to the patient has been to wear earplugs and a bathing cap for swimming. However, a significant pressure is required to force water through the grommet against the effects of surface tension, approximately 12 to 23 cm H2O (Pringle 1993). Thus water is unlikely to get into the middle ear while swimming on the surface, but water pressure while diving will be sufficient to force water through the grommet. Soapy water has a lower surface tension and is also more likely to go through the grommet at lower pressures. Studies have not shown an increased incidence of discharge in patients with grommets who go swimming (Pringle 1993).
Insertion of grommets produces patches of calcification, tympanosclerosis, in up to 60% of patients (Tos and Stangerup 1989). However, the hearing loss from this is not noticeable (Tos and Stangerup 1989), unless the tympanosclerosis affects virtually the entire tympanic membrane, which is very rare. When a grommet extrudes, it may leave a residual perforation in 1-2% of cases (Strachan et al 1996). This may slowly close with time, may not cause any symptoms in which case it does not require any treatment, or may lead to recurrent infections or prevent swimming in which case it can be repaired surgically.
Results: Ventilation tubes eliminate the conductive hearing loss due to middle ear fluid and produce improvement of hearing to normal levels while the ventilation tube is in position and patent. Dysequilibrium which occurs in up to 22% of children with glue ear is improved in up to 85% of these cases with insertion of ventilation tubes (Grace and Pfleiderer 1990).
Ventilation tubes can improve mild retraction of the tympanic membrane but do not seem to prevent the development of attic retraction pockets.
As mentioned earlier, about one third of patients require insertion of more than one set of grommets, and multiple insertions of grommets carry risks associated with anaesthesia and scarring of the tympanic membrane. Multiple grommet insertions are commoner in children who have their first set of grommets at a young age. To avoid multiple operations, long stay ventilation tubes were developed.
Long stay ventilation tubes- Theses are available in a variety of forms, including Goode T-Tubes and Shah permavent tubes. Insertion is rather more demanding than insertion of grommets, and the T-tubes are designed with larger flanges to stay in position for a prolonged period of time. The same complications can occur with T-tubes as with grommets. In addition, because the same tube stays in position for many years, it can become blocked with wax and require cleaning or replacement. Discharge is also more of a problem with T-tubes than grommets. The main problem with T-tubes is the high incidence of residual perforation following extrusion or removal, up to 25-40% (Strachan et al 1996).
Adenoidectomy: The adenoids are implicated in the aetiology of glue ear, whether by direct effects on Eustachian tube function or by acting as a source of infection, and adenoidectomy has been advocated as a treatment for glue ear. Studies suggest adenoidectomy alone may not be as effective as ventilation tubes alone ( Dempster et al 1993), but a combination of adenoidectomy and ventilation tubes is most effective (Maw and Bawden 1993), and adenoidectomy seems to reduce the number of further grommet insertions required ( Maw and Bawden 1994). Adenoidectomy also reduces the number of episodes of acute otitis media during the first few years. However, due to the risk of bleeding following adenoidectomy, the fact that it requires a slightly longer general anaesthetic and usually requires overnight stay in hospital, in many departments it is not performed as a first line procedure.
Tonsillectomy: There is no evidence to support the use of tonsillectomy for treatment of glue ear.
What treatment should be given?
Medical treatments on the whole only produce a short term benefit. Surgical treatment should only be considered in the presence of persistent glue ear present for three months or more, with significant hearing loss causing morbidity. Unilateral glue ear causing hearing loss is unlikely to cause significant morbidity and therefore is usually kept under observation, unless complications such as changes in the tympanic membrane develop. There is some evidence to suggest that prolonged hearing loss in one ear at a young age may interfere with development of binaural “stereo” hearing ( Moore et al 1991)but this needs further evaluation.
Exact treatment pathways differ from doctor to doctor, but one approach would be to insert grommets as a day case as the first surgical intervention, and if a second set of grommets was required, an adenoidectomy could be performed at the same time. If a third set of grommets was required, insertion of long stay ventilation tubes could be considered to reduce the number of operations required.
When should T-tubes be removed? There is no easy answer to this. If the T-tube is blocked or infected, removing it may be beneficial. If the tube is not causing any problems, the decision is more difficult. If the tube is removed too early, the middle ear effusion may recur. The tube cannot be left in indefinitely as it may restrict swimming and diving, and the risk of a residual perforation when the tube comes out is related to the duration of tube insertion. Sometimes the tube is only present in one ear, and if the other ear is healthy at that stage, this may suggest Eustachian tube function has improved and it is safe to remove the t-tube. The chances of a residual perforation can be reduced by freshening the edges of the perforation when the tube is removed. The decision about timing of t-tube removal will need to be discussed carefully with the patient or parents.
Glue ear in Adults:
Some children will continue to have poor Eustachian tube function and glue ear into adult life and require permanent ventilation tubes. Some adults will have poor Eustachian tube function secondary to allergy, rhinitis and sinusitis and tackling these problems may well improve middle ear ventilation. Temporary middle ear effusions are not uncommon following pressure changes as in flying, especially when the patient has recently had a cold. These usually resolve with the aid of decongestant nasal drops or sprays. Glue ear in one ear only needs to be investigated carefully as this may be the presenting sign of a cancer or other growth in the postnasal space pressing on the Eustachian tube. Examination of the postnasal space is mandatory in such patients, and usually requires a flexible endoscope. Even with the endoscope, some small tumours may be missed, so persistent glue ear in one ear requires examination of the postnasal space under a general anaesthetic and biopsy of the postnasal space.
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