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Management of chronic glue ear
Respiratory
Mini-symposium
Management of chronic glue ear
A. R.Maw many conditions affecting Eustachian tube function which may be associated with the development of middle ear effusion. There is an almost universal relationship with a cleft palate: and children with craniofacial abnormalities and syndromic conditions such as Down’s and Hurler’s syndromes frequently have middle ear fluid. Alteration of the mucociliary system by infection, allergy, immunological disturbance or cilia1 abnormality are associated with effusion. There is now evidence that the middle ear cleft behaves like a gas pocket and there are losses and gains both from the atmosphere via the Eustachian tube and also from the circulation by absorption and diffusion. Middle ear gas partial pressure composition is similar to that of mixed venous blood. Various risk factors known to be associated with the condition include, host factors (age, sex, racial, social, cultural, hygiene, nutrition, family history, immunological, physiological and pathological differences), environmental factors (climatic, seasonal, housing, crowding, schooling) and aetiological factors (micro-organisms, toxic substances and allergens). We have shown certain measurements of size in the nasopharynx to be smaller in children with glue ear compared with non affected controls.
‘Glue ear’ may be described as the presence within the middle ear cleft of an effusion which may be serous, seromucinous or mucoid but it is not frankly purulent. It is not usually associated with obvious signs or symptoms of infection, though bacteria may be cultured from the effusion in one third to one half of cases. It is known by a variety of synonyms including catarrhal, exudative, serous, secretory and non suppurative otitis media or otitis media with effusion. The latter term allows sub-division according to the type of effusion and also its duration.
Incidence and prevalence The condition runs a fluctuating course with a tendency to spontaneous resolution. Incidence and prevalence rates depend on methods used to detect the condition, and most commonly detection is by tympanometry and otoscopy. The incidence fits a logarithmic regression curve with an annual occurence of up to 40% in 2-year olds and 2% in 11-year olds. There are two prevalence peaks at 1 and 5 years of age.
Aetiology and risk factors The main factors responsible for middle ear effusions are infection and Eustachian tube dysfunction with development of a negative middle ear pressure. There is increasing evidence that the infective component of the condition originates in the nasopharynx. Whilst historically tubal dysfunction has been held as a principal cause, it now seems more likely that tubal pathology is an effect rather than a cause of the changes in the middle ear. There are, however,
Presentation and screening Presentation may be with overt hearing loss in older children but in infants the condition may be covert and detected on screening tests for hearing or may manifest itself by speech or language delay. There is usually an expressive speech abnormality and there may be behavioural problems or scholastic difficulties. Children may become insular, they may shout or increase the volume of the television, and some are seen to lip read. Sometimes episodes of acute infection are superadded to the chronic condition and then there is
A. Richard Maw MS, FRCS Consultant Otolaryngologist, Department of Otolaryngology, Bristol Royal Infirmary, Bristol BS2 8HW. Correspondence and requests for offprints to ARM. Current Paediofrics 8 1994 Longman
(1994) 4, 129-132
GroupLtd
129
130 CURRENT PAEDIATRICS otalgia and there may be otorrhoea. These episodes frequently coincide with a cold; upper respiratory tract infection, episode of allergic rhinitis or they may be a sequel to swimming.
Diagnosis Five factors help to confirm the presence of ‘glue ear’. Firstly, the history of hearing loss or of other effects due to hearing difficulty; secondly, otoscopic examination; thirdly, tympanometry which is rapid and reliable, and can be carried out in infants; fourthly, pure tone audiometry or behavioural testing using distraction techniques. The ‘gold standard’ for diagnosis of middle ear fluid is myringotomy and aspiration of the fluid. However, there has been a suggestion that nitrous oxide anaesthesia displaces middle ear fluid at operation which might account for some of the so-called ‘dry tap rate’.
Spontaneous course of the untreated disease Most episodes of ‘glue ear’ are short lived and 50% resolve within 3 months. Only 5% of cases will have persistent disease for more than a year. There is a seasonal variation to the condition and relapses and remissions may occur several years after the onset of the disease.’ There is little data regarding the long term rate of spontaneous resolution in severely affected cases which would otherwise have been treated surgically. In our study of severe established cases, in which only one ear was treated, gradual clearance of the effusion occurred in the unoperated ear without any treatment. After 1 year resolution occurred in 20%, 30% resolved after 2 years, 50% after 3, 60% after 4, 70% after 5, 85% after 7 years and 95% after 10 years. These otoscopic assessments were accompanied by a commensurate change from a flat type B to a peaked A Cl or C2 tympanometric trace. With these changes there was progressive hearing improvement. The median overall duration of the condition in its severe form without treatment has been calculated to be 6.1 years when assessed otoscopically and 7.8 years when assessed by tympanometry.2 Overall, however, and in particular in less severe cases, the natural history of the untreated condition is usually one of spontaneous resolution. Although the 95th percentile for duration in Dutch children was at 12 months, the median duration was 3 months or less.
Prevention There are few aspects of this condition which allow realistic preventative measures to be taken to reduce the incidence, duration or complications. Environmental manipulation Studies have shown a clear relationship between middle ear effusions and passive smoking. There has
been confirmation of an increased level of cotinine in children with effusions. We have shown an adverse effect, particularly of maternal smoking on the outcome of surgical treatment. Thus, removing a child from an environment of cigarette smoke may not only reduce the incidence of the condition but also improve the benefit due to surgical treatment. Knowledge that the condition is more prevalent in institutionalised children compared with those cared for at home may provide a possible means of reducing the rate of transference of upper respiratory tract infections in children of nursery school age. It is known that the surface endotoxin of haemophilus influenzae may be responsible for the induction of middle ear effusion and positive middle ear cultures for haemophilus are frequently found. It is possible that vaccination for haemophilus influenzae infection (Hib) may also result in some reduction in the incidence of the condition but many of these organisms are unencapsulated. Similarly, routine vaccination against pneumococcal infection may ultimately become a realistic option and further reduce the development of effusions.
Treatment Medical Topical and systemic decongestants, antihistamines and mucolytics and other remedies: Reasonably well controlled studies have shown that there is no significant benefit of any of these remedies. They may of course improve the child’s general catarrhal state but they will not resolve in the long term chronic effusion within the middle ear. There are no long term studies to support significant benefit from surfactant. There have been no further reports of benefit from gaseous ventilation of the middle ear with sulphahexofluoride. Reports of benefit from alternative therapies all lack support by properly executed, randomised controlled trials. Antibiotics: There have been many trials of treatment with a variety of antibiotics. A recent meta-analysis of 10 such trials performed between 1980 and 1990 in which there was adequate randomisation and use of either placebo or no drug control, suggested a rate difference in favour of antibiotics of 22.8%, but the end point was absence of effusion at the first post-treatment assessment, which was usually within weeks. None of the studies have followed cases in the long term, in a manner similar to trials of surgical treatment.3 However, an alternative interpretation of the same meta-analysis has failed to confirm a significant effect due to antibiotic treatment. These studies investigated co-trimoxazole, amoxicillin, co-amoxiclav, erythromycin, sul-
MANAGEMENT
phamethoxazole and cefaclor. From the evidence available it seems that there may be a short term benefit from antibiotics but long term data is unavailable, and all the studies show a high recurrence rate of the condition following completion of treatment. 3. Steroids: No studies of oral steroid treatment for glue ear have followed cases for more than a few weeks after discontinuing treatment. However, a meta-analysis of six trials comparing oral steroids with placebo have shown that after 7-14 days of medication there was a 3.6 times increased likelihood that the ears would be free from effusion at the end of treatment. Isolated studies have shown short term benefit with a combination of steroids with antibiotics, but again no long term data is available. There have been few studies demonstrating the effects of inhalational steroids but the management of associated nasal conditions or nasal allergy is said to improve Eustachian tube malfunction and may alter the outcome in some children. 4. Non-steroidal anti-inflammatory drugs: Aluminium ibuprofen for 2 weeks compared less favourably than trimethoprim with sulphamethoxazole or prednisolone in a study assessed after 4 and 12 weeks. A combination of antibiotics with naproxen as a prostaglandin inhibitor showed no effect on acute otitis media in relation to the development or persistence of subsequent glue ear. 5. Autoinflation: Initial studies with autoinflation of the Eustachian tube reported equivocal results and more recent attempts with conventional balloons have been ineffective. However, use of more sophisticated autoinflation equipment has been shown to have a short term therapeutic effect on chronic glue ear. We have demonstrated, in a carefully controlled prospective randomised study, that the beneficial effect may be maintained for at least 3 months, particularly if there is adequate compliance.4 6. Ampl@ication: Parental advice to provide clear, amplified speech is important in the management of all children with mild hearing impairment. Provision with a hearing aid may be beneficial in more severely affected cases, particularly if they are bilateral. There are, as yet, no properly controlled studies to show such benefit from use of hearing aids. Surgery From the description of the natural history of the condition it is clear that a ‘watch and wait’ policy must be the hallmark of management.’ In cases which do not resolve and in which there is obvious hearing difficulty or effects on speech, language, learning and behaviour as a consequence of hearing loss and in which the condition is seen to be persistent
OF CHRONIC
GLUE EAR
131
for several months, there may be a need for surgical treatment. Such treatment is directed to: relieve the hearing loss; prevent the development of complications in the middle ear cleft; reduce the rate of recurrence of the condition following treatment. There should be clear guidelines laid down for referral of cases for surgical treatment. The condition will be nearly always bilateral, though occasionally unilateral cases will need surgery. Confirmation of the presence of effusions should be made by pneumatic otoscopic examination and, if necessary, with microscopy. Tympanometry should be performed to demonstrate absence of a peak and verification of a flat type B trace. Finally, there should be assessment of hearing thresholds in each ear by appropriate behavioural testing or pure tone audiometry. Aural treatment
Under general anaesthesia myringotomy is performed, the effusion is aspirated and a ventilation tube or ‘grommet’ is inserted. Without a tube the incision heals and the effusion recurs. The choice of tube is determined by the desired period of middle ear reventilation. Usually a short stay type of tube is inserted which remains in place for 9-12 months before spontaneous extrusion from the tympanic membrane occurs. Reinsertion of such tubes on a second or subsequent occasion is generally required in about 30% of cases and parents should be warned of this. Premature extrusion and the need for reinsertion led to the development of so-called long stay or tympanostomy tubes with wider, larger intratympanic flanges. Prolonged retention leads to accumulation of debris around the tube and an unacceptably high incidence of persistent perforations once the tubes have extruded. Some surgeons recommend them for use in syndromic children or those with a cleft palate in which the condition is known to be longlasting. Such advice should be given with caution and it may be more prudent to recommend repeated insertions of short stay tubes. Non-aural treatment
There have been a variety of trials to show whether there is benefit from adenoidectomy and adenotonsillectomy in the treatment of chronic glue ear. Most of the studies have at least some problem of design. These may be either due to small numbers studied in the trial, a high ‘dry tap rate’ at operation or an unknown ‘dry tap rate’. Some studies have a short period of follow-up and those of less than 12 months comparing the effects of adenoidectomy and tube insertion are obviously
132
CURRENT PAEDIATRICS
not long enough to show any extra long term benefit which might be due to adenoidectomy. In some studies there is a significant loss to follow-up and in others both unilateral and bilateral cases are considered together. In some studies the treatment is changed during the course of the study and others fail to mention whether observations are made blind. Finally, in many there is exclusion of children with severe nasal problems and those with severe hearing loss. Few studies have assessed adenoidectomy alone but many compare the effects of adenoidectomy and tubes compared with tubes alone. Ventilation tubes have an immediate beneficial effect on hearing thresholds but after 9 months there is no difference from the effect from a tube and that from adenoidectomy. Adenoid removal has been shown to produce better normalisation of middle ear function and cases treated with adenoidectomy have less time with otitis media compared with controls during the first 2 years. Most studies have shown a greater relapse rate in non-adenoidectomy cases and we have shown significantly greater need for re-treatment with ventilation tubes in cases who have not also received adenoidectomy. Our studies show a beneficial effect of adenoidectomy on fluid clearance from the middle ear for up to four years after treatment but the most sign$cant clearance results from combination of adenoidectomy and insertion of a tube. The effect of adenoidectomy appears to be
related to the age at which surgery is carried out and, to some extent, to the size of the nasopharynx and the post nasal space airway.2 We have shown that tonsillectomy does not confer any additional benefit in terms of clearance of the effusion or tympanometric change, compared with adenoidectomy alone. At the present time many but not all adenoidectomy operations are carried out on an overnight stay basis whereas insertion of ventilation tubes is carried out as a day case. In the future it is anticipated that both operations will be day-case procedures. Complications of surgery
Aural complications following insertion of a tube may be immediate or delayed. Approximately 10% of cases develop post intubation otorrhoea and this usually resolves following treatment with topical antibiotic and steroid ear drops. Development of tympanosclerosis occurs in approximately 50% of cases treated with tubes, whereas only 3% of untreated ears develop sclerosis. Long term studies show that this condition is only infrequently associ-
ated with a hearing loss and when this occurs it is not greater than three or four decibels.6 Permanent perforation occurs after insertion of a short term grommet in about 3% of cases but with long stay tympanostomy tubes this may be up to 50%. However, this type of case is generally more severe at the outset and may have pre-existing atelectasis or collapse of the tympanic membrane, which is thin and more susceptible to perforation. Non-aural complications result from adenoidectomy. Haemorrhage occurs postoperatively in l-3% of cases, either as a primary or secondary event. In a small number of cases following removal of the adenoids there may be failure to occlude the nasopharynx during speech, giving rise to velopharyngeal insufficiency or hypernasality. Complications occurring as a result of surgery need to be distinguished from those resulting from the disease process within the middle ear cleft. Development of atelectasis or collapse of the tympanic membrane and the gradual erosion of the outer attic wall or attic retraction, appear to be related in part to the overall duration of the effusion. Insertion of ventilation tubes do not seem to prevent the development of these serious sequelae of middle ear effusions. Glue ear remains the commonest reason for admission to hospital for elective surgery in small children. There are still a large number of features of the condition and of its treatment which are contentious and require clarification. Further long term prospective studies with sufficiently large numbers of children are required to clarify the uncertainties. A multi-centre pilot study has recently been set up by the Medical Research Council to investigate these problems.
References 1. Zielhuis GA, Rach GH, Van den Broek P. Screening for otitis media with effusion in pre school children. Lancet 1989; 1: 311-314. 2. Maw AR, Bawden R. Spontaneous resolution of severe chronic glue ear in children and the effects of adenoidectomy, tonsillectomy and insertion of ventilation tubes (grommets). BMJ 1993; 306: 756-760. 3. Rosenfeld RM, Post JC. Meta-analysis of antibiotics for the treatment of otitis media with effusion. Otolaryngol Head Neck Surg 1992; 106: 378-386. 4. Blanshard JD, Maw AR, Bawden R. Conservative treatment of otitis media with effusion by autoinflation. Clin Otolaryngol 1993; 18: 188-192. 5. Effective Health Care. The treatment of persistent glue ear in children. 1992 4 University of Leeds. 6. Maw AR. Development of tympanosclerosis in children with otitis media with effusion and ventilation tubes. Clin Otolaryugol 1991; 105: 614-617.
Mini-symposium
Management of chronic glue ear
A. R.Maw many conditions affecting Eustachian tube function which may be associated with the development of middle ear effusion. There is an almost universal relationship with a cleft palate: and children with craniofacial abnormalities and syndromic conditions such as Down’s and Hurler’s syndromes frequently have middle ear fluid. Alteration of the mucociliary system by infection, allergy, immunological disturbance or cilia1 abnormality are associated with effusion. There is now evidence that the middle ear cleft behaves like a gas pocket and there are losses and gains both from the atmosphere via the Eustachian tube and also from the circulation by absorption and diffusion. Middle ear gas partial pressure composition is similar to that of mixed venous blood. Various risk factors known to be associated with the condition include, host factors (age, sex, racial, social, cultural, hygiene, nutrition, family history, immunological, physiological and pathological differences), environmental factors (climatic, seasonal, housing, crowding, schooling) and aetiological factors (micro-organisms, toxic substances and allergens). We have shown certain measurements of size in the nasopharynx to be smaller in children with glue ear compared with non affected controls.
‘Glue ear’ may be described as the presence within the middle ear cleft of an effusion which may be serous, seromucinous or mucoid but it is not frankly purulent. It is not usually associated with obvious signs or symptoms of infection, though bacteria may be cultured from the effusion in one third to one half of cases. It is known by a variety of synonyms including catarrhal, exudative, serous, secretory and non suppurative otitis media or otitis media with effusion. The latter term allows sub-division according to the type of effusion and also its duration.
Incidence and prevalence The condition runs a fluctuating course with a tendency to spontaneous resolution. Incidence and prevalence rates depend on methods used to detect the condition, and most commonly detection is by tympanometry and otoscopy. The incidence fits a logarithmic regression curve with an annual occurence of up to 40% in 2-year olds and 2% in 11-year olds. There are two prevalence peaks at 1 and 5 years of age.
Aetiology and risk factors The main factors responsible for middle ear effusions are infection and Eustachian tube dysfunction with development of a negative middle ear pressure. There is increasing evidence that the infective component of the condition originates in the nasopharynx. Whilst historically tubal dysfunction has been held as a principal cause, it now seems more likely that tubal pathology is an effect rather than a cause of the changes in the middle ear. There are, however,
Presentation and screening Presentation may be with overt hearing loss in older children but in infants the condition may be covert and detected on screening tests for hearing or may manifest itself by speech or language delay. There is usually an expressive speech abnormality and there may be behavioural problems or scholastic difficulties. Children may become insular, they may shout or increase the volume of the television, and some are seen to lip read. Sometimes episodes of acute infection are superadded to the chronic condition and then there is
A. Richard Maw MS, FRCS Consultant Otolaryngologist, Department of Otolaryngology, Bristol Royal Infirmary, Bristol BS2 8HW. Correspondence and requests for offprints to ARM. Current Paediofrics 8 1994 Longman
(1994) 4, 129-132
GroupLtd
129
130 CURRENT PAEDIATRICS otalgia and there may be otorrhoea. These episodes frequently coincide with a cold; upper respiratory tract infection, episode of allergic rhinitis or they may be a sequel to swimming.
Diagnosis Five factors help to confirm the presence of ‘glue ear’. Firstly, the history of hearing loss or of other effects due to hearing difficulty; secondly, otoscopic examination; thirdly, tympanometry which is rapid and reliable, and can be carried out in infants; fourthly, pure tone audiometry or behavioural testing using distraction techniques. The ‘gold standard’ for diagnosis of middle ear fluid is myringotomy and aspiration of the fluid. However, there has been a suggestion that nitrous oxide anaesthesia displaces middle ear fluid at operation which might account for some of the so-called ‘dry tap rate’.
Spontaneous course of the untreated disease Most episodes of ‘glue ear’ are short lived and 50% resolve within 3 months. Only 5% of cases will have persistent disease for more than a year. There is a seasonal variation to the condition and relapses and remissions may occur several years after the onset of the disease.’ There is little data regarding the long term rate of spontaneous resolution in severely affected cases which would otherwise have been treated surgically. In our study of severe established cases, in which only one ear was treated, gradual clearance of the effusion occurred in the unoperated ear without any treatment. After 1 year resolution occurred in 20%, 30% resolved after 2 years, 50% after 3, 60% after 4, 70% after 5, 85% after 7 years and 95% after 10 years. These otoscopic assessments were accompanied by a commensurate change from a flat type B to a peaked A Cl or C2 tympanometric trace. With these changes there was progressive hearing improvement. The median overall duration of the condition in its severe form without treatment has been calculated to be 6.1 years when assessed otoscopically and 7.8 years when assessed by tympanometry.2 Overall, however, and in particular in less severe cases, the natural history of the untreated condition is usually one of spontaneous resolution. Although the 95th percentile for duration in Dutch children was at 12 months, the median duration was 3 months or less.
Prevention There are few aspects of this condition which allow realistic preventative measures to be taken to reduce the incidence, duration or complications. Environmental manipulation Studies have shown a clear relationship between middle ear effusions and passive smoking. There has
been confirmation of an increased level of cotinine in children with effusions. We have shown an adverse effect, particularly of maternal smoking on the outcome of surgical treatment. Thus, removing a child from an environment of cigarette smoke may not only reduce the incidence of the condition but also improve the benefit due to surgical treatment. Knowledge that the condition is more prevalent in institutionalised children compared with those cared for at home may provide a possible means of reducing the rate of transference of upper respiratory tract infections in children of nursery school age. It is known that the surface endotoxin of haemophilus influenzae may be responsible for the induction of middle ear effusion and positive middle ear cultures for haemophilus are frequently found. It is possible that vaccination for haemophilus influenzae infection (Hib) may also result in some reduction in the incidence of the condition but many of these organisms are unencapsulated. Similarly, routine vaccination against pneumococcal infection may ultimately become a realistic option and further reduce the development of effusions.
Treatment Medical Topical and systemic decongestants, antihistamines and mucolytics and other remedies: Reasonably well controlled studies have shown that there is no significant benefit of any of these remedies. They may of course improve the child’s general catarrhal state but they will not resolve in the long term chronic effusion within the middle ear. There are no long term studies to support significant benefit from surfactant. There have been no further reports of benefit from gaseous ventilation of the middle ear with sulphahexofluoride. Reports of benefit from alternative therapies all lack support by properly executed, randomised controlled trials. Antibiotics: There have been many trials of treatment with a variety of antibiotics. A recent meta-analysis of 10 such trials performed between 1980 and 1990 in which there was adequate randomisation and use of either placebo or no drug control, suggested a rate difference in favour of antibiotics of 22.8%, but the end point was absence of effusion at the first post-treatment assessment, which was usually within weeks. None of the studies have followed cases in the long term, in a manner similar to trials of surgical treatment.3 However, an alternative interpretation of the same meta-analysis has failed to confirm a significant effect due to antibiotic treatment. These studies investigated co-trimoxazole, amoxicillin, co-amoxiclav, erythromycin, sul-
MANAGEMENT
phamethoxazole and cefaclor. From the evidence available it seems that there may be a short term benefit from antibiotics but long term data is unavailable, and all the studies show a high recurrence rate of the condition following completion of treatment. 3. Steroids: No studies of oral steroid treatment for glue ear have followed cases for more than a few weeks after discontinuing treatment. However, a meta-analysis of six trials comparing oral steroids with placebo have shown that after 7-14 days of medication there was a 3.6 times increased likelihood that the ears would be free from effusion at the end of treatment. Isolated studies have shown short term benefit with a combination of steroids with antibiotics, but again no long term data is available. There have been few studies demonstrating the effects of inhalational steroids but the management of associated nasal conditions or nasal allergy is said to improve Eustachian tube malfunction and may alter the outcome in some children. 4. Non-steroidal anti-inflammatory drugs: Aluminium ibuprofen for 2 weeks compared less favourably than trimethoprim with sulphamethoxazole or prednisolone in a study assessed after 4 and 12 weeks. A combination of antibiotics with naproxen as a prostaglandin inhibitor showed no effect on acute otitis media in relation to the development or persistence of subsequent glue ear. 5. Autoinflation: Initial studies with autoinflation of the Eustachian tube reported equivocal results and more recent attempts with conventional balloons have been ineffective. However, use of more sophisticated autoinflation equipment has been shown to have a short term therapeutic effect on chronic glue ear. We have demonstrated, in a carefully controlled prospective randomised study, that the beneficial effect may be maintained for at least 3 months, particularly if there is adequate compliance.4 6. Ampl@ication: Parental advice to provide clear, amplified speech is important in the management of all children with mild hearing impairment. Provision with a hearing aid may be beneficial in more severely affected cases, particularly if they are bilateral. There are, as yet, no properly controlled studies to show such benefit from use of hearing aids. Surgery From the description of the natural history of the condition it is clear that a ‘watch and wait’ policy must be the hallmark of management.’ In cases which do not resolve and in which there is obvious hearing difficulty or effects on speech, language, learning and behaviour as a consequence of hearing loss and in which the condition is seen to be persistent
OF CHRONIC
GLUE EAR
131
for several months, there may be a need for surgical treatment. Such treatment is directed to: relieve the hearing loss; prevent the development of complications in the middle ear cleft; reduce the rate of recurrence of the condition following treatment. There should be clear guidelines laid down for referral of cases for surgical treatment. The condition will be nearly always bilateral, though occasionally unilateral cases will need surgery. Confirmation of the presence of effusions should be made by pneumatic otoscopic examination and, if necessary, with microscopy. Tympanometry should be performed to demonstrate absence of a peak and verification of a flat type B trace. Finally, there should be assessment of hearing thresholds in each ear by appropriate behavioural testing or pure tone audiometry. Aural treatment
Under general anaesthesia myringotomy is performed, the effusion is aspirated and a ventilation tube or ‘grommet’ is inserted. Without a tube the incision heals and the effusion recurs. The choice of tube is determined by the desired period of middle ear reventilation. Usually a short stay type of tube is inserted which remains in place for 9-12 months before spontaneous extrusion from the tympanic membrane occurs. Reinsertion of such tubes on a second or subsequent occasion is generally required in about 30% of cases and parents should be warned of this. Premature extrusion and the need for reinsertion led to the development of so-called long stay or tympanostomy tubes with wider, larger intratympanic flanges. Prolonged retention leads to accumulation of debris around the tube and an unacceptably high incidence of persistent perforations once the tubes have extruded. Some surgeons recommend them for use in syndromic children or those with a cleft palate in which the condition is known to be longlasting. Such advice should be given with caution and it may be more prudent to recommend repeated insertions of short stay tubes. Non-aural treatment
There have been a variety of trials to show whether there is benefit from adenoidectomy and adenotonsillectomy in the treatment of chronic glue ear. Most of the studies have at least some problem of design. These may be either due to small numbers studied in the trial, a high ‘dry tap rate’ at operation or an unknown ‘dry tap rate’. Some studies have a short period of follow-up and those of less than 12 months comparing the effects of adenoidectomy and tube insertion are obviously
132
CURRENT PAEDIATRICS
not long enough to show any extra long term benefit which might be due to adenoidectomy. In some studies there is a significant loss to follow-up and in others both unilateral and bilateral cases are considered together. In some studies the treatment is changed during the course of the study and others fail to mention whether observations are made blind. Finally, in many there is exclusion of children with severe nasal problems and those with severe hearing loss. Few studies have assessed adenoidectomy alone but many compare the effects of adenoidectomy and tubes compared with tubes alone. Ventilation tubes have an immediate beneficial effect on hearing thresholds but after 9 months there is no difference from the effect from a tube and that from adenoidectomy. Adenoid removal has been shown to produce better normalisation of middle ear function and cases treated with adenoidectomy have less time with otitis media compared with controls during the first 2 years. Most studies have shown a greater relapse rate in non-adenoidectomy cases and we have shown significantly greater need for re-treatment with ventilation tubes in cases who have not also received adenoidectomy. Our studies show a beneficial effect of adenoidectomy on fluid clearance from the middle ear for up to four years after treatment but the most sign$cant clearance results from combination of adenoidectomy and insertion of a tube. The effect of adenoidectomy appears to be
related to the age at which surgery is carried out and, to some extent, to the size of the nasopharynx and the post nasal space airway.2 We have shown that tonsillectomy does not confer any additional benefit in terms of clearance of the effusion or tympanometric change, compared with adenoidectomy alone. At the present time many but not all adenoidectomy operations are carried out on an overnight stay basis whereas insertion of ventilation tubes is carried out as a day case. In the future it is anticipated that both operations will be day-case procedures. Complications of surgery
Aural complications following insertion of a tube may be immediate or delayed. Approximately 10% of cases develop post intubation otorrhoea and this usually resolves following treatment with topical antibiotic and steroid ear drops. Development of tympanosclerosis occurs in approximately 50% of cases treated with tubes, whereas only 3% of untreated ears develop sclerosis. Long term studies show that this condition is only infrequently associ-
ated with a hearing loss and when this occurs it is not greater than three or four decibels.6 Permanent perforation occurs after insertion of a short term grommet in about 3% of cases but with long stay tympanostomy tubes this may be up to 50%. However, this type of case is generally more severe at the outset and may have pre-existing atelectasis or collapse of the tympanic membrane, which is thin and more susceptible to perforation. Non-aural complications result from adenoidectomy. Haemorrhage occurs postoperatively in l-3% of cases, either as a primary or secondary event. In a small number of cases following removal of the adenoids there may be failure to occlude the nasopharynx during speech, giving rise to velopharyngeal insufficiency or hypernasality. Complications occurring as a result of surgery need to be distinguished from those resulting from the disease process within the middle ear cleft. Development of atelectasis or collapse of the tympanic membrane and the gradual erosion of the outer attic wall or attic retraction, appear to be related in part to the overall duration of the effusion. Insertion of ventilation tubes do not seem to prevent the development of these serious sequelae of middle ear effusions. Glue ear remains the commonest reason for admission to hospital for elective surgery in small children. There are still a large number of features of the condition and of its treatment which are contentious and require clarification. Further long term prospective studies with sufficiently large numbers of children are required to clarify the uncertainties. A multi-centre pilot study has recently been set up by the Medical Research Council to investigate these problems.
References 1. Zielhuis GA, Rach GH, Van den Broek P. Screening for otitis media with effusion in pre school children. Lancet 1989; 1: 311-314. 2. Maw AR, Bawden R. Spontaneous resolution of severe chronic glue ear in children and the effects of adenoidectomy, tonsillectomy and insertion of ventilation tubes (grommets). BMJ 1993; 306: 756-760. 3. Rosenfeld RM, Post JC. Meta-analysis of antibiotics for the treatment of otitis media with effusion. Otolaryngol Head Neck Surg 1992; 106: 378-386. 4. Blanshard JD, Maw AR, Bawden R. Conservative treatment of otitis media with effusion by autoinflation. Clin Otolaryngol 1993; 18: 188-192. 5. Effective Health Care. The treatment of persistent glue ear in children. 1992 4 University of Leeds. 6. Maw AR. Development of tympanosclerosis in children with otitis media with effusion and ventilation tubes. Clin Otolaryugol 1991; 105: 614-617.