Journal of the Royal Society of Medicine Volume 84 October 1991
Otitis media and its sequelae
N Shah FRCS DLO
The Royal National Throat, Nose & Ear Hospital, London WC1X 8DA
Keywords: otitis media; hearing loss; glue ear; treatment
Many patients with chronic otitis media are referred or present themselves for the first time with a short history of symptoms. However, a careful detailed history invariably elicits a past history of otitis media in childhood. Otitis media is a serious disease with potential lifethreatening complications. This has been recognized from ancient times. Hippocrates in 460 BC noted that 'Acute pain of the ear with continued high fever is to be treated, for the patient may become delerious and die'. It was also noted by Celsus in 25 AD that 'Inflammation and pain of the ear sometimes leads to insanity and death'. Before the days of antibiotics, one in every 40 deaths in a large hospital was caused by an intracranial complication of otitis media. Today these dreaded complications are rare in so-called developed countries, and this may be attributed to improved housing, better nutrition, higher host resistance, a decrease in virulence or change in the micro-organisms and more effective treatment. However, in the developing world these infections appear frequently, last longer and lead to a higher mortality where nutrition is poor and medical care is not readily available or too expensive'.
Acute otitis media Acute otitis media usually follows an upper respiratory infection, and is very common in young children. In the United Kingdom, acute otitis media is a disease of general practice and almost all children are treated by general practitioners23. Very few children are referred to hospital for specialist advice. The report of an MRC working party4 on acute otitis media in general practice found a peak incidence at 6 years of age, falling rapidly to a low level in adult life. Recently Bain5 and Ross et al.6 have reported a higher incidence of otitis media in infants in general practice. In a study of the epidemiology of otitis media in 2565 children from Boston, Teele et al7 disclosed an incidence of 50% by one year of age, rising to 75% by 3 years. Similarly, in Sweden, Ingvarsson et al.8 in a study of 8900 children, found that children between 6 and 11 months of age were at the greatest risk for otitis media. The recurrence rate was also higher in those who had their first attack before the age of 18 months. The incidence of otitis media and the distribution of age groups in the UK, USA and Europe are different and this is not easily explained. In the USA most children are seen by paediatricians and in the European system children are seen in local health clinics by specialists, whilst in the UK children are primarily seen in the GP's surgery at the request of a parent. It is very likely that many cases of milder attacks of otitis media without acute symptoms of pyrexia or discharge never reach the surgery.
Next to upper respiratory infection, otitis media is the most common organic disease in childhood, and yet, there is a great deal of confusion about its aetiology, pathogenesis, diagnosis and treatment. In order to gather first hand information, early this year a personal survey about otitis media amongst 45 general practitioners revealed that the incidence of otitis media in practice was 5-10% and diagnosis was based mainly on redness (colour) of the drum, earache and discharge. Formal hearing assessments were not made. Most children were treated by antibiotics and amoxycillin was the drug of choice. Follow-up was variable, from 5 to 10 days. Thereafter children were not seen again unless requested by the parents. Children with recurrent infections, discharge or persistent hearing loss noticed by the parents were referred for specialist advice. Whilst waiting for an outpatient clinic appointment many children suffered from so-called repeated attacks and were treated with further courses of antibiotics. No information was available on the resolution of the infection.
Based on Presidential Address read to Sectiokof Otology, 2 November 1990
Middle ear effusion The relationship between acute otitis media and middle ear effusion (glue ear) is unclear; however, there is a clear link, but often it is difficult to distinguish between acute infections or chronic middle ear effusion. In the Boston study6 referred to earlier it was found that middle ear effusion persisted for weeks to months following an episode of acute otitis media. Following the first attack of otitis media, 70% of children had fluid in the middle ear after 2 weeks, 40% had fluid after one month, 20% had fluid after 2 months, and 10%o had fluid after 3 months. Thus, the symptoms of acute infection diminish within a short period, but the fluid persists in the middle ear for a long time and some ears labelled as 'glue ears' are in fact unresolved otitis media. Many infants and young children with middle ear effusions- are asymptomatic and the condition often resolves spontaneously within a few weeks. Surveys of healthy children for the presence of middle ear effusions have been conducted by Sly et al.9 in the USA and by Poulson, Tos and colleagues'0 in Scandinavia in which tympanometric screening demonstrated that up to 40% of children may have effusions at one time or another. A similar study of 250 normal nursery school children in the London Borough of Camden by Shah" employing a Peters AP 61 Acoustic Impedance Bridge also disclosed a 40% incidence of unsuspected fluid in the middle ears. Many of these children were from professional parents including doctors and nurses. 0141-0768/91/ 100581-06/$02.00/0 Incidence © 1991 Middle ear effusion (glue ear) is most commonly The Royal recognized in school children and is often discovered Society of during routine screening when a child starts school. Medicine
Journal of the Royal Society of Medicine Volume 84 October 1991
Although the true incidence is not known, it is estimated that one in four children under the age of 10 years is affected some time in their early years. An average of 10 or more new cases are seen at Gray's Inn Road every working day. A large number of infants and preschool children also suffer from this condition but owing to their inability to convey the problem, the relative lack of symptoms and the difficulties of examination and diagnosis, combined with the NHS referral system, it may remain undetected for a long time during an important period of learning and speech development. An analysis ofchildren admitted under one surgeon at Gray's Inn Road in one year showed that 34% were under the age of 5 years. Of these, the average age when first seen in the clinic was 3 years. The sources of referral were as follows: community physicians, 42%; general practitioners 32%; paediatricians 12% and others 14%. Whilst many children with effusion are asymptomatic, recurrent infections and speech delay in infants, with hearing loss in older children, are the common complaints. Otitis media and middle ear eff-usion are uncommon in adults. Those who do suffer from transient episodes find it extremely difficult to cope with their work and are not prepared to wait for natural-resolution or are satisfied with reassurance. If the incidence of middle ear effusion was as common in adults as it is in children, many more patients would be referred for early opinion, advice and treatment. The reasons for referral of children at the hospital were mixed: hearing loss+speech problems, 43%; hearing loss, 41% and delayed speech, 11%. Other additional symptoms were otalgia, hyperacusis, excess wax formation, falling over, nasal obstruction, snoring and behaviour problems. The average age at which parents believed that the condition began was 22 months of age, however, 25% of parents had no idea for how long the child had been experiencing problems. The average time that elapsed between the parents' suspicion first being aroused and the child eventually being seen in the clinic was 16 months. In hospital practice, the presence of fluid in the middle ear can usually be easily identified but in a busy general practice this can be difficult. The narrowness of the canals of infants, poor co-operation, the presence of wax deep in the canal (often pushed in by cotton-buds), or a poor light source can make it very difficult to visualize the drum; and the absence of tympanometry makes it even more difficult for the correct diagnosis to be made. If the drum is visible, the typical findings are; a dull, yellow, amber coloured, retracted tympanic membrane. The malleus handle appears shorter, broader and whiter than normal. The short process is very prominent. Mobility is impaired and the light reflex is absent. However, the colour varies from normal grey to pink, slate grey, blue, dull red and rarely, green. There may be a retraction pocket, which may give an erroneous impression of being a perforation, and occasionally there is crust formation (cast) covering the entire surface of the tympanicmembrane.
Hearing tests In older children in whom reliable pure tone audiometry is possible, the audiogram reveals a
moderate 30-40 dB conductive hearing loss in the speech frequencies. In young children a free field speech discrimination test with familiar words is more reliable than a doubtful sweep audiogram. In some children the pure tone audiogram may be almost normal, and yet the parents complain that their child does not hear well and has educational problems. In a study of one group of such children, the hearing, tested by conventional pure tone audiometry, was compared with speech audiometry in free field using the Manchester word list. This showed that, even when the pure tone audiogram was normal, speech discrimination could still be impaired. Thus a pure tone audiogram alone is not an adequate guide for assessing the disability, and children with educational and speech problems need very careful assessment. Many children with hearing thresholds of 20 dB are considered to be 'within normal limits'. However, most normally hearing adults have no idea what an infant with such an apparently minor loss actually hears. A child with an unilateral hearing loss with one good (normal) ear has no serious effects; problems arise when the better hearing ear develops a fluctuating hearing loss as a result of effusion. The inherent difficulties of testing hearing in young children, combined with inadequate masking, may result in delay in recognizing that a child has no useful hearing (dead ear) in one ear or has high frequency hearing loss in both ears. Tympanometry In the years since Metz's12 initial report and subsequent studies by Brooks'3 and others, the clinical value of acoustic admittance measurements is well recognized and its routine use for both diagnosis and screening is now widespread. Although an experienced otologist can usually identify the presence of effusion in the middle ear by oto/microscopy it is difficult in some cases, particularly, infants and difficult-to-test patients. Therefore tympanometry offers an objective, reliable and quick method of testing middle ear function. Modern instruments can provide a graphic record within a few seconds. In a typical case of middle ear effusion the tympanogram is usually flat, and the acoustic reflex is absent. Tympanometry is useful in monitoring the progress of middle ear infection. As the infection resolves, there is a change in middle ear pressure which can be recorded on each visit. All children admitted for surgery should have pre-operative tympanometry and audiometry where possible and the decision to insert grommets should be made before and not at surgery. Tympanometry is also helpful in testing the patency of a grommet. Acoustic admittance measurement is an important tool in audiological evaluation but it must be remembered that tympanometry does not replace careful clinical evaluation.
Management In many children otitis mediawitheffusion is transitory and the most conservative treatment is careful followupwithoutany medication. No specific drugisavailable which will cure the disease, but most children, by the time they reach the specialist for advice, have already had trials with multiple courses of antibiotics, oral and nasal decongestants without real benefit. The aim of treatment is to remove the cause of the problem;.
Journal of the Royal Society of Medicine Volume 84 October 1991
ie, to evacuate fluid from the middle ear by myringotomy and suction, and in most cases to insert a grommet. The number of such operations performed at Gray's Inn Road in the last 10 years has more than doubled. The decision whether to operate or to wait should depend on the patient's age, speech development, degree of hearing loss, symptoms and appearance of the tympanic membrane. A young child with a history of recurrent middleear infections, speech delay or other disabilities should be operated upon without delay. During the last 2 years 45 otitis-prone infants had grommets inserted with cessation of infections and immediate improvement in their speech development. Older children with fluctuating hearing loss, few symptoms and no social or educational problems may be left alone, provided regular follow-up is maintained. However, a child with recurrent pain, behavioural or educational problems or signs of retraction pocket, even if the hearing is normal, needs early ventilation, if long-term complications are to be avoided.
The grommet The idea of introducing an indwelling tube for maintaining an opening in the tympanic membrane is not new. Politzer in the 1860s employed a hollow, hard rubber eyelet with a silk string, similar to the present day grommet. However, it was Armstrong'4 who reintroduced the use of a plastic tube. Many tubes (grommets) of different sizes, shapes and materials are readily available and used in daily practice. In a controlled study Shah15, evaluating the use of unilateral grommet, showed that the hearing in the ear with the grommet was normal as long as the tube was in place and patent. After using the Shepard grommet for a few months, it was obvious that an extended lip on the lower edge, like a shoe horn, would make the insertion of the grommet easier. This idea was put to the President of Richards Medical Co., and prototypes were available for trial in 1971. Within a few months the new Shah grommet was commercially available and is now in common use. A Shah Mini Tube, with the same design, was introduced in 1983 for very small narrow ear canals, grossly retracted, atrophic tympanic membranes, and fascial graft or drum remnant during tympanoplasty. More recently another tube - the Shah Permavent tube - made from high grade silicone has been introduced for long-term ventilation.
Equipment Whilst operating microscope models have changed, most surgeons still use the Gruber metal speculum and a large bayonet ended Agnew's myringotome. However, a black plastic speculum with large serrated upper end and an angled, oval-shaped lower end allows a better grip and view of the canal and for myringotomy a disposable, malleable sickle knife is easier to use. Although labelled 'disposable' they can be re-used after sterilization. Occasionally very fine microscissors are employed to enlarge the opening in a very thin drum when pressure with a knife is likely to tear or damage an atrophic membrane. The technique A 4 mm size speculum is introduced and gently rotated until it fits snugly in the canal. Cerumen plugs and debris are gently removed with suction or
fine forceps without trauma to the canal skin. The external canal may be irrigated with isotonic saline but it is unnecessary to use any other cleansing agents. The tympanic membrane is carefully examined. Occasionally the surface is covered with a cast, which should be gently lifted and removed. The anterior canal wall is often prominent and it may be difficult to insert the tube in the preferred anterior segment. It is advisable to make two incisions in the membrane, a smaller radial incision for the tube and another slightly larger one for aspiration of the mucoid fluid. Very often the canal is narrow in small children; the tube is then placed postero-inferiorly, and the fluid is aspirated from the anterior incision. Damage to the drum/ossicles or canal wall should be avoided. If there is excess bleeding, it should be controlled by topical application of epinephrine solution, in order to avoid blockage of the tube and secondary infection. The method of holding the grommet depends upon the site of insertion. For an anterior placement, the tube may be held at the top end of the tube, and for posteroinferior placement it is held on the inferior edge. The small triangular flange is inserted first and firm counter pressure is applied to the opposite end until the tube slips in to the middle ear like a button. It is useful to instil a few drops of clear antibioticsteroid drops (Sofradex) in the ear in order to prevent any blood clotting and blocking the tube. Air bubbles appear through the lumen of the tube; and escape of this gas varies. It is reduced in atelectatic ears, and may provide an additional useful information about the status of the middle ear mucosa-ventilation and is called an 'air bubble test'. A rolled piece of cotton wool used as a wick is placed in the meatus and it is removed after an hour. Usually the meatus and the tube are left clean, and free from blood. Parents are given written instructions on ear care on discharge from the hospital. The child is seen for a postoperative check and hearing test after 4 weeks, and thereafter at 6-monthly intervals until the grommets have extruded from the ears. Children are discharged from the clinic when the ears are free from effusion for a period of 6 months or more and the hearing has remained normal.
Special problems Severe unilateral or bilateral hearing loss associated with middle ear effusion can pose a difficult management problem. A child with middle ear effusion in the only hearing ear needs careful assessment, treatment and follow-up. In such cases, myringotomy and adeno-tonsillectomy is performed in the first instance and the insertion of grommet is deferred. In children with bilateral severe sensorineural hearing losses the presence of an ear mould in the canal often predisposes to secondary infection when there is a grommet in the ear, and the child may be unable to use or wear the hearing aid. It is important that these problems are discussed in great detail, and everyone including the child, the parents, teacher of the deaf, GP and the school are well informed so that unnecessary anxiety, frustration, multiple visits and second opinions are avoided. The effusion In most children the fluid is mucoid, but in infants it may be mucopurulent. Traditionally, the effusions
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have been thought to be sterile or to contain organisms considered to be nonpathogenic, but some effusions do yield positive bacterial cultures. Healey16, Giebink et al.17, Lim'8 and many other workers have isolated bacteria varying from 20% to 50% of cultures. The organisms commonly recovered are H. influenzae, S. pneumoniae, and Staph. aureus. Many middle ear effusions may be ofbacterial origin but the infection is limited by the defence mechanism of the middle ear. In 1972 Shah and Rees employed a disposable glass suction cannula similar to the Zollner suction tube - made from a Pasteur pipette - to obtain cultures (unpublished observations). The fluid was aspirated directly from the middle ear avoiding contamination. The results in 80 ears were as follows: sterile, 60 ears; Staph. albus, 12 ears; H. Streptococcus, 5 ears; Staph. pyogenes, 3 ears.
Complications Myringotomy and insertion of a grommet is the commonest ENT operation and it is often left to the most junior member of the surgical team. Every operation has some risks and the insertion of a grommet is no exception. In experienced hands, it is a safe procedure, but some complications may arise. A lost grommet This can only happen in the hands of an inexperienced surgeon when the incision in the tympanic membrane is rather large. Usually, it can be removed by making a separate radial incision, without recourse to tympanotomy. Occasionally, it may be completely covered with desquamated epithelium and be difficult to visualize.
Bleeding Excess bleeding is common in young children when the tympanic membrane is inflamed and thickened. However, very rarely bleeding from a high jugular bulb can also occur.
Discharge In most children, there is no discharge soon after the insertion of a grommet. However, in infants the middle ear is often filled with mucopurulent fluid (subacute otitis media) and it may continue to drain like an abscess for a few days. It is important to counsel the parents. In these children, oral antibiotics as well as topical ear drops for a few days may be prescribed, until the ears are clean and dry. Unilateral, persistent or recurrent discharge may be due to a primary cholesteatoma and this needs careful assessment. It may present as typical bilateral glue ear, but under the microscope an opaque mass may be seen under the tympanic membrane. Late discharge usually follows an upper respiratory infection, rhino-sinusitis, or entrance of water into the ear after a shampoo or swimming. It often starts as otitis externa. The combination of accumulated squamous debris around the tube, moisture and humidity provide an ideal culture medium for infection. Although the discharge is not accompanied by pain or other constitutional symptoms, it is unsightly and many parents find. it difficult to cope. These children are usually seen by their general practitioners first and oral antibiotics are commonly prescribed. The treatment required is local toilet and suction clearance. In infants where suction is difficult,
the ear can be cleaned by gentle syringing. Topical use of drops for a few days is all that is necessary. Blood stained discharge, although uncommon, can occur as a result of granulation - polyp formation around the tube - particularly with a long-term T tube. A small polyp will regress with topical treatment, but a large polyp will require careful examination under GA.
Grommets and swimming This topic is controversial and there is a difference of opinion among the specialists. There is a higher incidence of infection in infants, and in children with rhinitis/sinusitis. It is advisable to protect the ears with clean ear plugs and a bathing cap, and to avoid underwater swimming and diving. In older children the use of a nose-clip may be helpful. Unfortunately, many doctors, parents and teachers fail to realize that infection can spread via the nose and eustachian tube, even if the ears are well protected by customized silicone ear moulds. Blocked grommet The lumen of the tube can be blocked by dried secretion, when the thick fluid is not adequately aspirated. It can also be blocked by a blood clot, or the entire grommet may be -obscured by a large dried scab in the canal. Again the topical use of drops may be helpful, but occasionally the tube has to be removed or replaced.
Tympanosclerosis The presence of a grommet in the tympanic membrane will cause a reaction due to surgical trauma, bleeding, foreign body reaction and the healing-regenerative process. Theoretically, a large foreign body with a perforation should also interfere with vibration of the tympanic membrane, resulting in hearing impairment but in practice it does not seem to have a serious effect. Mackinnon'9 was one of the first to describe the association of hyalinosis with grommet insertion. He thought it due to a pathological change associated with advanced exudative otitis media and not due to the grommet itself. Tympanosclerosis is commonly observed at the site of incision but more often in the peripheral part of the tympanic membrane. There is a continuous change in the extent and location of tympanosclerosis and small areas of fibrosis and scarring disappear with time. The exact mechanism of this development is not clear. Many older patients with presbyacusis also show evidence of varying degrees of tympanosclerosis, although they have never received grommets. Following the regular use of a long-term Permavent tube in selected patients, it has been encouraging to find very little new development of tympanosclerosis and it is felt that the silicone material ofthe tube may be an important preventive factor. To clarify this point, a controlled trial using a regular Shah grommet in one year and a trimmed Permavent silicone tube in the opposite ear of new patients is underway. At the end of 11 months three grommets have extruded, showing minimal scarring in the drum; whilst all permavent tubes are in place.
Extrusion of grommet Sooner or later almost all tubes are extruded. The average period for a Shah tube to remain in place is
Journal of the Royal Society of Medicine Volume 84 October 1991
9 months and even longer when placed in the anterosuperior quadrant. In infants, following an acute infection, it is extruded earlier by pushing out through a weakened area of the drum. It is also extruded quickly from a thin atrophic membrane. After a few months the tube may appear to be in place but not functioning due to the formation of a membrane at the deeper end. It is believed that natural migration of the squamous epithelium plays an important role in extrusion of the tube. The rate and speed of migration vary with the presence or absence of inflammation. The migratory activity is enhanced in the presence of inflammation, as seen in otitis externa. The tubes stay in place longer if the epithelial debris is prevented from accumulating around the lip ofthe grommet and this can be achieved by regular use of ear drops. Migration of epithelium on the surface of the tympanic membrane was described by Alberti20 and recently by Michaels and Soucek2l. However, Bateman22 observed similar migration of the dark spot (blood clot) after a myringotomy incision. This 'ink dot test' also provides a useful guide in the management of retraction pockets. When an ink-dot placed in the deep recess, fails to migrate to the periphery, the pocket is unsafe. This is an indication for surgical intervention. Failure to extrude On very rare occasions the tube in one ear may fail to extrude naturally. This may be due to impaction in the anterior recess or to accumulation of crust around the tube. It is important to know whether the tube is patent or blocked, and the condition of the opposite ear before it is removed. If the other ear is free from recurrence of effusion for a year and the middle ear pressure as measured by tympanometry is normal, the tube may be removed under light anaesthesia. Usually the perforation left after removal of the tube will close quickly, but the margins of the perforation may be freshened at the time of removal. A tiny piece of Gelfoam may be placed to cover the defect and may promote healing and early closure.
Mastoid air cell system The relationship between chronic middle ear inflammation and pneumatization of the mastoid temporal bone is controversial. Diamant23 described his hereditary theory of pneumatization in 1940 and he believed that hereditary factors had a much more significant effect on pneumatization than the environment. X-ray studies, analysis of case records and operative findings coiifirm that over 75-80% of ears with chronic ear disease have poorly pneumatized sclerotic mastoids. Whether middle ear infection (otitis media) in infancy inhibits the development of the air cell system or a poorly developed air cell system predisposes to infection is not clear. Stangerup and Tosn2 in a prospective study of children with bilateral secretory otitis media, inserted a ventilating tube in one ear only and showed that the 'largest air cell system' was found on the side where the tube had been inserted. They also found that the children who had chronic secretory otitis media in infancy had significantly smaller air cell systems than the children who were free from middle ear disease. Children with upper respiratory infections
develop middle ear effusions, which hamper the pneumatization process and result in a smaller air cell system. In another study of 25 randomly selected patients with cleft palate, Dolan25 emphasized the association between eustachian tube function and mastoid air cell size and concluded that the air cell system was smaller in patients with otitis media. In our patients, X-rays (mastoids) carried out before and after surgery at 6 monthly intervals, showed marked improvement in aeration and clearance of the air cell system. The role of adenoids Adenoidectomy with or without tonsillectomy is often performed at the same time as insertion of grommets for chronic secretory otitis media. The number of such operations performed at Gray's Inn Road during the last 15 years has not changed. Whilt the number of tonsillectomy and adenoidectomy operations has declined, the figure for adenoidectomy operations has remained virtually the same. The indications for adenoidectomy are not clearly defined and many children with recurrent otitis media are referred for adenoidectomy in the hope of preventing further episodes of infection. Maw26, in his prospective randomized controlled studies, attempted to demonstrate a rationale for this commonly performed procedure and concluded that adenoidectomy has a significant short-term therapeutic effect. However, most children with persistent recurrences have had multiple operations, including adenoidectomy. Recurrence of effusion The aetiology and pathogenesis of middle ear effusion is not clear, but usually there is physiological dysfunction of the Eustachian tube. Insertion of a grommet bypasses the Eustachian tube and its beneficial effects are well known. Unfortunately, after extrusion of a grommet many children have a recurrence of effusion and require further surgery. This creates anxiety, and a loss of faith in the operation amongst many parents. To avoid misunderstanding and allay fear, it is important to counsel parents about the real purpose of ventilation of the middle ear cleft, namely, to restore normal hearing and prevent educational disability until the child 'grows out of it', at approximately 11-12 years of age.
Long-term ventilation Most otologists recognize the need for occasional longterm ventilation and the Goode T tube is the most commonly used. Gibb27 and East28 reported their experiences with trimmed Per Lee tubes. Although the Per Lee tube has the correct shape, it is rather large and stifffor use in children and in ears with thin atrophic tympanic membranes. Many authors have reported a high incidence ofcomplications with the use of T tubes. Crabtree29 described the use of Mesh tubes for long-term ventilation. This tube, which was originally designed for an endolymphatic shunt operation, was modified for its use in the middle ear. Personal experience with this tube, now known as 'The Shah Permavent tube',30 was presented in June 1988 at The Third International conference on Cholesteatoma and Mastoid surgery held in Copenhagen. At present this tube is regularly used for long-term ventilation of the middle ear cleft.
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Retraction pockets Persistent negative pressure in the middle ear may result in retraction of the tympanic membrane, atelectasis, erosion of bone and the development of a deep retraction pocket, as commonly seen in the attic and the posterosuperior quadrant of the tympanic membrane. Once the pocket is established migrating squamous epithelium - keratin - may accumulate and, if not evacuated, it may later invade the middle ear cleft. The true incidence, duration and susceptibility to the development of retraction pockets is not known, but, once a pocket is established, it may progress rapidly in the direction of the attic and rarely towards the hypotympanum. In patients with a poorly pneumatized air cell system and a small shallow mesotympanum, an inflammation of the middle ear cleft may lead to occlusion of the air spaces due to swelling of the mucosa. The middle ear mucosal folds - the chorda and tensor folds - may be well developed and complete but usually there are two channels connecting the attic with the mesotympanum. Once these channels are blocked, there may be complete separation of the attic from the mesotympanum. In these cases, even if the middle ear is ventilated by a tube, the retraction pocket in the attic may continue to progress towards cholesteatoma and inevitable mastoid surgery. The number of new patients seeking treatment for chronic otitis media has dropped and is likely to decline further in the next decade, provided we continue to treat middle ear infections effectively. It is our duty to inform and educate our colleagues, and to identify the children who are 'at risk', if long-term complications and mastoid surgery are to be avoided. Acknowledgments: I would like to acknowledge my grateful thanks to Mr Andrew Gardner (Clinical Photographic Department), Mr Peter Zwarts (Institute Library) and Mr John Ballantyne for a critical review of the manuscript. References 1 Gadre KC. Complications of cholesteatoma. In: Tos M, Thomsen J, Peitersen E, eds. Cholesteatoma and mastoid surgery. Amsterdam: Kugler & Ghedini, 1988:1117-21 2 Fry J. The catarrhal child. London: Butterworths, 1961 3 Fry J. Management of patients with inflammatory middle ear disease. Prescribers J 1984;24:15-19 4 MRC Report. Acute otitis media in general practice. Lancet 1957;ii:510-14 5 Bain DJG. Acute otitis media in general practice. Practitioner 1981;225:1568-75 6 Ross AK, Croft PR, Collins M. Incidence of acute otitis media in infants in a general practice. JR Coll Gen Pract 1988;38:70-2 7 Teele DW, Klein JO, Rosner BA. Epidemiology of otitis media in children. Ann Otol Rhinol Laryngol 1980; 89:5-6
8 Ingvarsson L, Lundgren K, Olofsson B, Wall S. A prospective study of acute otitis media in children. Acta Otolaryngol 1982;(suppl 388):1-52 9 Sly RM, Zambie MF, Fernandes DA. Tympanometry in Kindergarten children. Ann Allergy 1980;44:1-7 10 Poulson G, Tos M. Screening tympanometry in newborn infants during the first six months of life. Scand Audiol 1978;7:159-66 11 Shah N. Glue ears. Dev Med Child Neurol 1977;19:825-6 12 Metz 0. The acoustic impedance measured on normal and pathological ears. Acta Otolaryngol 1946;(suppl 63):1-254 13 Brooks DN. An objective method of detecting fluid in the middle ear. J Int Audiol 1968;7:280-6 14 Armstrong BW. A new treatment for chronic secretory otitis media. Arch Otolaryngol 1954;59:653-4 15 Shah N. Use of grommets in glue ears. JLaryngol Otol 1971;85:283-7 16 Healey GB, Teele DW. The microbiology of chronic middle ear effusions in children. Laryngoscope 1977; 87:1472-8 17 Giebink GS, Mills EL, Huff JS. The microbiology of serous and mucoid otitis media. Pediatrics 1979; 63:915-19 18 Lim DJ. Microbiology and cytology of otitis media with effusion. In: Sade J, ed. Secretory otitis media and its sequelae. New York: Churchill Livingstone, 1979:125-43 19 Mackinnon DM. The sequel to myringotomy for exudative otitis media. J Laryngol Otol 1971;85:773-93 20 Alberti PW. Epithelial migration on the tympanic membrane. J Laryngol Otol 1964;74:808-30 21 Michaels L, Soucek S. Development of stratified squamous epithelium of the human tympanic membrane. Am J Anat 1989;184:334-44 22 Bateman GH. Secretory otitis media. J Laryngol Otol 1957;71:261-70 23 Diamant M. Otitis and pneumatisation of the mastoid bone. Lund, Sweden: Hakon Olsons Boktryckeri, 1940: 1-149 24 Stangerup SE, Tos M. Treatment of secretory otitis media and pneumatisation. Laryngoscope 1986;96:680-4 25 Dolan KD. Mastoid pneumatisation. In: Sade J, ed. Secretory otitis media and its sequelae. Churchill Livingstone 1979:298-313 26 Maw AR. Chronic otitis media with effusion and adenotonsillectomy. In: Lim DJ, Bluestone C, Klein JO, Nelson BC, eds. Recent advances in otitis media with effusion. Philadelphia: Decker Inc 1983:299-302 27 Gibb AG. Long term tympanic ventilation by Per-Lee tubes. J Laryngol Otol 1986;100:503-8 28 East D. The use of Per-Lee ventilation tube in the management of refractory secretory otitis media. J Laryngol Otol 1986;100:509-13 29 Crabtree JA. Permanent ventilating tube. Otol Clin North Am 1970;3:61-5 30 Shah N. Prevention of chronic otitis media; prolonged ventilation by permavent tube. In: Tos M, Thomsen J, Peitersen E, eds. Cholesteatoma and mastoid surgery. Amsterdam: Kugler & Ghadini, 1988:755-7
(Accepted 12 March 1991)