Patulous Eustacian Tube
Schwartze first described patulous eustachian tube in 1864 when he noted a scarred atrophic eardrum moving synchronously with respiration. This condition was first fully described in 1867 by Jago, who had a patulous eustachian tube. Problem Patulous tube is a troublesome but benign condition in which the eustachian tube remains abnormally patent. Frequency Incidence of patulous eustachian tube is 0.3-6.6%, and 10-20% of persons who have it are bothered enough by symptoms to seek medical attention. This condition is more common in females than in males and is usually present in adolescents and adults; it is rarely found in young children. Etiology In most instances, patulous eustachian tube is idiopathic. Weight loss (sometimes caused by chronic illness) and pregnancy are identified as important predisposing factors. Neurologic disorders that may cause muscle atrophy (eg, stroke, multiple sclerosis, motor neuron disease) have been implicated. Adhesion formation in the nasopharynx following adenoidectomy or radiotherapy may also predispose individuals to a patulous tube. The condition is sometimes associated with medications (eg, oral contraceptives, diuretics). Other predisposing factors include fatigue, stress, anxiety, exercise, and temporomandibular joint syndrome. Pathophysiology Under normal resting conditions, the eustachian tube is closed and only opens with swallowing or autoinflation. In unaffected individuals, closure of the eustachian tube is maintained by luminal and extraluminal factors, which include intrinsic elasticity of the tube, surface tension of moist luminal surface, and extraluminal tissue pressure. Muscle tone of tensor veli palatini dilates the lumen; damage to tensor veli palatini following cleft palate surgery may produce a patulous tube. Weight loss can also lead to abnormal patency caused by reduced tissue pressure and loss of fat deposits in the eustachian tube region. Pregnancy alters opening pressures of the eustachian tube because of the change in surface tension; estrogens acting on prostaglandin E affect surfactant production. Scarring in the postnasal space following adenoidectomy may result in traction of the tube in a patent position.
Major symptoms of patulous eustachian tube include fluctuating aural fullness, roaring tinnitus synchronous with nasal respiration, audible respiratory sounds, distorted autophony (ie, the abnormal perception of one’s own breath and voice sounds) with echoing occasionally severe enough to interfere with speech production, and sensation of plugged ear. Autophony is the most frequent symptom associated with patulous tube. Vertigo and hearing loss can also occur because patulous eustachian tube allows excessive pressure changes to occur in the middle ear; these pressure changes are then transmitted to the inner ear through ossicular movement. Some patients may have difficulty eating because the noise of chewing is transmitted to the ear. Patulous eustachian tube is often misdiagnosed because symptoms mimic those of middle ear effusion. Symptoms may relate to cyclical changes occurring in the mucosa of the eustachian tube. Some patients find relief from the associated increased mucosal congestion by lying down, by putting the head between the knees, or during upper respiratory tract infection. Compression of the jugular veins produces peritubular venous congestion and may relieve symptoms. Patients sometimes sniff repetitively to close the eustachian tube, and this may lead to long-term negative middle ear pressure. Decongestants or a ventilation tube in the drum can worsen symptoms. Diagnosis can often be made based on history alone.
Examination findings are usually unremarkable; canals and eardrums appear normal. The eardrum can be atrophic secondary to the constant drum motion from breathing or sniffling. Synchronous movement of the tympanic membrane with respiration is exaggerated with forced respiration or with the patient breathing in and out through the nose with one nostril occluded; the tympanic membrane moves medially on inspiration and laterally on expiration. With the patient sitting upright, small movements of pars flaccida occur, which disappear when the patient is supine. Examine the ear with an operating microscope to detect subtle movements. Indications Surgery is indicated if the patient continues to have significant otologic symptoms despite medical therapy. Contraindications Surgical therapy is contraindicated in patients who are pregnant or have mild symptoms. These patients need informative reassurance alone. Workup Imaging Studies CT scanning in an axial plane has been used to show the presence of a patulous eustachian tube.CT scanning may be useful in making the diagnosis in some patients.Radiology only assists in the diagnosis of anatomic patency. Other Tests Tympanometry may detect movements of the tympanic membrane with nasal respiration, especially with the patient in an erect position.Distorted sounds of nasal respiration and speech may be heard with a microphone placed in the external meatus.With sonotubometry, a test sound is introduced into the nasal vestibule and a microphone is fitted into the external auditory meatus. With a patulous tube, sound pressure level in the external canal is at a maximum; because the tube does not close, no sudden drop in transmitted sound occurs.Observe a regular change in middle ear pressure when increasing or decreasing the ambient pressure during the measurement of impedance in a pressure chamber. Usual variations in pressure with opening and closing of the tube are not seen because the tube remains open all of the time. Diagnostic Procedures In some patients with patulous tube, direct nasopharyngoscopy may show the continuous presence of a triangular opening of the eustachian tube orifice.Transnasal endoscopic (video analysis) exam has been used to study the nasopharyngeal opening of the eustachian tube during rest, swallowing, and yawning.
Patients who are pregnant and those with mild symptoms (most patients) need informative reassurance alone. Patients who have symptoms during pregnancy are symptom-free after delivery. Advise patients to do the following: Increase or regain lost weightAvoid diureticsRecline or lower head when symptoms occur Topical administration (nasal preparation) with anticholinergics may be effective for some patients. Estrogen (Premarin) nasal drops (25 mg in 30 mL normal saline, 3 gtt tid) or oral administration of saturated solution of potassium iodide (10 gtt in glass of fruit juice tid) has been used to induce swelling of the eustachian tube opening. Nasal medication containing diluted hydrochloric acid, chlorobutanol, and benzyl alcohol has been demonstrated to be effective in some patients. This has been reported to be well tolerated with little or no adverse effects. Approval by the Food and Drug Administration (FDA) is pending. Reserpine and SSKI have also been advocated.
The following methods may be used for treatment of a narrow lumen caused by inflammatory response or scar tissue: Bezold’s remedy of insufflation of a solution of salicylic acid and boric acid (1:4 ratio) (Repeat treatments are always necessary.)Eustachian tube diathermy with sequential application of ureteric diathermy probeCautery with 20% silver nitrate Electrocoagulation has been discarded because of morbidity (ie, damage to middle cranial fossa dura, damage to mandibular nerve). The following methods may be used for treatment of a narrow lumen caused by extrinsic compression: Paraffin injectionTeflon injection anterior to the eustachian tube orifice (Serious complications may occur.)Gelfoam injection (Results are good, but temporary; very little morbidity is associated.) Autologous fat or cartilage graft plugging of the eustachian tube at its nasopharyngeal orifice, in conjunction with myringotomy & ventilation tube placement, has been successful in some patients.Alter function of palatal muscles with or without pterygoid hamulotomyStroud et al (1974) described transposition of tensor veli palatini tendon medial to pterygoid hamulus (transpalatal approach).Transection of tensor veli palatini is another option.Occlusion of the eustachian tubeBluestone and Cantekin (1981) recommend occlusion of bony eustachian tube with an intravenous indwelling catheter via anterior tympanotomy. A catheter is filled with methyl methacrylate glue, and the tympanostomy tube is inserted to aerate the middle ear and prevent development of serous effusion. The catheter can be removed at any time. Dr. Pou at Harvard has been doing this successfully. A modification of the Bluestone technique involves placement of the catheter through myringotomy.Myringotomy and insertion of a ventilating tubeThis may provide temporary relief for some patients.These steps are relatively simple to perform and reversible and have minimal complications.Occasionally, myringotomy and insertion of a ventilating tube result in increasing the patient’s discomfort.Surgical scar tissue removal in nasopharynx: This may benefit patients with adhesions from a prior operation. Outcome and Prognosis Patients with vestibular symptoms experience improvement of vertigo with treatment of patulous tube.
Future and Controversies
A discussion of the merits of different treatments is restricted by insufficient numbers and by lack of adequate long-term follow-up data to allow valid conclusions to be drawn. Very little basic research has been performed to investigate mechanisms responsible for normal eustachian tube function. Until more basic research and properly conducted trials are performed, this situation is likely to remain.