The condition
The Eustachian tube is a narrow tube which links the back of the nose to the middle ear. It is normally closed but opens when we swallow, yawn or chew. The Eustachian tube has three main functions: to protect the middle ear from pathogens; to ventilate the middle ear, which can help to keep the air pressure equal on either side of the eardrum, enabling the eardrum to work and vibrate properly; and to help drain secretions from the middle ear cleft.
Eustachian tube dysfunction (ETD) is the inability of the Eustachian tube to adequately perform these functions. However, the precise function and mechanisms of the Eustachian tube and the underlying causes of dysfunction are complex and not fully understood.1 From a diagnostic perspective, ETD is also poorly defined.
Eustachian tube dysfunction may occur when the mucosal lining of the tube is swollen, or does not open or close properly.2 If the tube is dysfunctional, symptoms such as muffled hearing, pain, tinnitus, reduced hearing, a feeling of fullness in the ear or problems with balance may occur. Long-term ETD has been associated with damage to the middle ear and the eardrum.3 Complications include otitis media with effusion (glue ear), middle ear atelectasis (retraction of the eardrum), and chronic otitis media.1,3 However, the role of the Eustachian tube in the development of other middle ear conditions is not fully understood.1 Middle ear ventilation is increasingly seen as being associated with other mechanisms, such as those relating to gaseous exchange through the middle ear mucosa.4,5 Therefore, it may be that problems with middle ear ventilation (and therefore symptoms and signs previously attributed to ETD) may not all be associated with problems with or dysfunction of the Eustachian tube. Abnormal patency (patulous Eustachian tube) is a separate condition, in which the Eustachian tube remains intermittently open, causing an echoing sound of the person’s own heartbeat, breathing, and speech.
Aetiology and prevalence
The lining of the Eustachian tube can become swollen and the Eustachian tube can become dysfunctional following the onset of an infectious or inflammatory condition such as an upper respiratory tract infection, allergic rhinitis or rhinosinusitis, leading to difficulties in pressure equalisation, discomfort and other symptoms.6,7 Nasal septal deviation has also been associated with symptoms of ETD; this is based on some studies which suggested that, in patients who were unable to equalise pressure during scuba training or submarine service, submucous resection of the nasal septum resolved apparent ETD symptoms.8–11 Dysfunction of the Eustachian tube may also be related to failure of the muscles associated with Eustachian tube opening.1 Extrinsic compression of the Eustachian tube potentially due to inflammation or enlargement of the adenoids, tumour or trauma may also result in ETD,2,12 although these conditions and their management are beyond the scope of this review. The incidence of ETD is disproportionately high in patients with cleft palate who may be considered a discrete clinical population.12 Other potential risk factors include tobacco smoke, reflux and radiation exposure.13–15 There appears to be no association with sex,1 although it has been suggested that ethnicity and geographical factors (such as proximity to the poles) are associated with increased incidence and prevalence.1,16
There are limited data on ETD prevalence and incidence, which may reflect the lack of consensus regarding how ETD is defined. A UK national study of hearing17 reported that 0.9% of the 2708 adults assessed (from an initial sampling of 48,313) were considered to have ETD, based on otoscopic examination and audiological assessment. However, this may be an underestimate; a recent study stated that most otolaryngologists encounter a much higher incidence of the condition in their practices.18
Diagnosis
There are no comprehensive guidelines on diagnosis of ETD.19 Diagnosis is generally based on medical history and clinical examination to identify potential underlying causes.19 The UK national survey defined ETD as the presence of a normal or abnormal but intact tympanic membrane with a middle ear pressure of < –100 mmH2O and an air–bone gap of ≥ 15 decibels (dB).17 The criteria were used for a presumptive diagnosis of ETD. The authors noted that it was a relatively non-specific category, which may include patients in the early or late stages of an episode of otitis media with effusion. However, the presence of either of these signs is not usually considered to be either necessary or sufficient for the diagnosis of ETD in clinical practice; while negative middle ear pressure often indicates ETD, patients with ETD may have normal middle ear pressure and those with negative middle ear pressure may be asymptomatic. Moreover, while an intact eardrum was a requirement of the survey criteria, several investigators include patients with perforated eardrums.20–25
Although not used in the survey, symptoms of dysfunction are usually a necessary condition for diagnosis in clinical practice. Common diagnostic factors include the inability to ‘clear’ or ‘pop’ the ear with changes in barometric pressure, together with other patient-reported symptoms (e.g. aural fullness, pain, muffled hearing).19 There are a number of tests that are used to inform diagnosis: otoscopy, tympanometry and nasal endoscopy are initial options in a secondary care setting. Evidence on the predictive value of Eustachian tube function tests is limited, and several tests may be needed for a more reliable and comprehensive assessment of Eustachian tube function.1 Currently, there is no commonly used patient-reported outcome measure. A scale for the assessment of ETD [the 7-item Eustachian Tube Dysfunction Questionnaire (ETDQ-7)] was tested for validity; this is a questionnaire addressing a range of symptoms associated with ETD, which is completed by the patient. The data available on reliability were based on a relatively small number of patients (n = 50) and controls (n = 25), but the test discriminated patients and controls and exhibited good test–retest reliability.26 However, this represents a recent development and it is not yet widely used. Another relevant scale which is also completed by patients, the 22-item Sinonasal Outcome Test (SNOT-22), has been used to assess symptoms of the related condition of rhinosinusitis.27
The lack of clearly defined diagnostic criteria, together with the uncertainty relating to the aetiology of ETD, presents a key challenge in undertaking a review of interventions for its treatment. Lack of consensus on the necessary features for diagnosis, including clinical history, requires additional awareness of the risk of error and bias in the selection of studies, as well as increasing the probability of clinical heterogeneity in the included studies.
Current research and guidance
Research on treatments for ETD as a distinct condition in adults is limited. A single systematic review was identified in the scoping searches for the current review (see the review protocol).28 Published in 2002, the previous review had a limited search (MEDLINE and PubMed only) and included a range of interventions and preclinical studies as well as those in both children and adults. It has been recommended that this review be updated.29 The only guidance relating to ETD treatment which was identified by the scoping searches was issued by the National Institute for Health and Care Excellence (NICE) on balloon dilatation of the Eustachian tube in November 2011.30 Based on a rapid review of literature,31 three case series were identified,32–34 of which two were published only as conference abstracts.32,34 The guidance concluded that current evidence on the efficacy and safety of the procedure is inadequate in quantity and quality. NICE recommended that the intervention should only be used in the context of research; future research should address the efficacy of the procedure in the short and longer term, report data on safety outcomes, clearly describe which parts of the Eustachian tube are treated and report subjective measurements of symptom improvement as well as objective measurements of Eustachian tube function.
Other systematic reviews of existing research which were identified assessed treatments for related conditions such as childhood glue ear and otitis media with effusion.35–37 NICE guidance has also been issued on the treatment of these conditions.38 There have also been Cochrane reviews in conditions such as tympanic membrane retraction pockets in adults and children.39
Management
Although ETD symptoms are common, they are often mild and generally resolve after a few days. Simple actions such as swallowing, yawning, chewing or forced exhalation against a closed mouth and nose can help to equalise pressure in the middle ear and resolve symptoms. However, symptoms sometimes persist, in which case treatment may be desirable. There are a number of non-surgical and surgical treatment options aimed at improving Eustachian tube function, but there is limited consensus about management.
Non-surgical
Non-surgical management strategies include:
Active observation, which involves monitoring the symptoms to determine whether or not they naturally resolve.
Supportive care, which includes advice about self-management such as to swallow, yawn, or chew to help equalise the pressure in the middle ear.
Pressure equalisation methods, which is a technique whereby the Eustachian tube is reopened by raising the pressure in the nose. This can be achieved in several ways, including forced exhalation against a closed mouth and nose (Valsalva manoeuvre). Other methods include blowing up a balloon through each nostril, using an anaesthetic mask36 or the use of mechanical devices.40,41 The aim is to introduce air into the middle ear, via the Eustachian tube, equalising the pressures and allowing better fluid drainage.
Nasal douching, in which the nasal cavity is washed with a saline solution to flush out excess mucus and debris from the nose and sinuses.42
Decongestants, antihistamines, nasal or oral corticosteroids which are aimed at reducing nasal congestion and/or inflammation of the lining of the Eustachian tube.
Antibiotics, for the treatment of rhinosinusitis.
Simethicone, which is currently being investigated in adults to assess whether or not it can help to break up bubbles that may block the opening of the Eustachian tube in the back of the nose during a cold, allowing air to pass between the nose and middle ear.43 This is not currently a management option used in the UK.
Surgical
We understand that, currently, the main surgical treatment in the UK is a pressure equalising tube (also known as tympanostomy tube, ventilation tube or grommet) which is inserted into the eardrum through a small incision. Pressure equalising tubes typically extrude after 6–9 months. Long-acting tubes are occasionally used, although these may be prone to crusting, infection, obstruction and permanent tympanic membrane perforation. This may be performed under either general or local anaesthesia. Newer surgical methods which are mainly used in the context of research include:
Balloon dilatation (dilatation) of the Eustachian tube, a procedure which aims to dilate the Eustachian tube and improve its function. It consists of introducing a balloon catheter into the Eustachian tube through the nose, under transnasal endoscopic vision. The balloon is filled with saline. Pressure is maintained for approximately 2 minutes, following which the balloon is emptied and removed. The procedure has been performed experimentally under local and general anaesthesia.
Transtubal application of fluids, an emerging approach for the application of fluids to the middle ear via the Eustachian tube. The transtubal application approach involves placing a nasal microendoscope within the Eustachian tube under local anaesthesia via its nasopharyngeal opening. Subsequently, fluids are applied through an additional working channel after microendoscopic evaluation.44
Eustachian tuboplasty, an emerging treatment in which a laser or rotary cutting tool is used to strip away enlarged mucous membranes and cartilage to clear obstruction to the Eustachian tube. Tuboplasty has been used in patients with chronic ETD as an alternative to pressure equalising tubes which may have extruded on numerous occasions.23,32 The intervention has also been used for middle ear atelectasis or serous effusion.45
There is no consensus on indications for treatment, or on the optimal timing of the interventions. Surgical interventions are generally (though not exclusively) used where ETD is resistant to other interventions. A step-up approach is usually adopted, from primary to secondary and tertiary care settings. Treatment choice is based on aetiology, severity and persistence of symptoms, as well as the degree of invasiveness of the treatment and surgical preference.
Decision problem
Although diagnostic and treatment suggestions exist, for example websites such as BMJ (British Medical Journal) Best Practice, there is a lack of comprehensive diagnostic and treatment guidelines and no recent systematic review assessing the effectiveness of interventions for ETD in adults. The National Institute for Health Research (NIHR) Health Technology Assessment (HTA) commissioning brief requested a wide systematic review including best available evidence in order to provide primary and secondary care practitioners with evidence about the value of referral, advise surgeons on the effectiveness of surgical interventions and inform recommendations for future research.
As outlined above, key challenges in undertaking a systematic review of treatments for ETD are that ETD is an ill-defined condition and there is a lack of consensus about its diagnostic criteria. In order to provide an informative overview of the evidence, a pragmatic approach was taken regarding how the condition was defined.
The aim of the systematic review was to determine the clinical effectiveness of treatments for adult ETD, and to identify gaps in the evidence in order to inform future research.
