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Eustachian Tube
The Eustachian tube connects the middle ear cavity to the nasopharynx. It has three parts - a bony portion, a junctional portion, and a cartilaginous portion. The cartilaginous portion is normally closed but opens during swallowing due to the action of the tensor veli palatini and levator veli palatini muscles. The Eustachian tube functions to ventilate and drain the middle ear and protect it from pressure changes and pathogens from the nasopharynx. Dysfunction can lead to conditions like otitis media and patulous Eustachian tube. Evaluation methods include otoscopy, endoscopy, Valsalva maneuver, and ty
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Eustachian Tube
- 1. EUSTACHIAN TUBE AND ITS DYSFUNCTION -Dr.Alka Kapil
- 2. Eustachian tube isa part of system including the nose , palate, rhinopharynx, and middle ear spaces
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- 4. 4 Tubo-tympanic recess,derived from endoderm of 1st pharyngeal pouch Distal portion - middle ear cavity Proximal portion - Eustachian tube cartilage and muscles - surrounding mesoderm
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- 6. Eustachian tube anatomy •Narrow osteocartilaginous channel connecting the tympanic cavity to the nasopharynx • Allows passage of : air and fluid • Begins at tymapnic orifice at protympanum & ends at pharyngeal orifice on the lateral wall of nasopharynx • Hourglass shaped of two unequal cones
- 7. • Total lengthof ET is 33 mm : -bony part 6.5mm -junctional part 3mm -cartilagionus part 23.5mm • Bony portion patent all times • Fibrocartilaginous portion that is - closed at rest - opens during swallowing or when forced to open, such as during the Valsalva maneuve • Lining epithelium: pseudo stratified ciliated columner
- 8. Mid cartilaginous portionof the Eustachian tube The cross-sectional view through the lumen shows two different compartments: 1. Rüdinger’s safety canal – filled with air or with mucus; likely always open 2. Auxiliary gap – has longitudinal mucosal folds. contributes to the clearance and protection function
- 10. Saggital cadeveric cutthrough left Middle ear bony Eustachian tube (Pr) and the canal of tensor tympani muscle (asterisk), the isthmus (I), the cartilaginous Eustachian tube (ET), and its inferiorly related levator veli palatini muscle (LVP). The superior wall of the bony Eustachian tube is formed by the tegmen tubari
- 11. Tensor veli palatini: bony wall of the scaphoid fossa and from the entire length of the short lateral lamina of the cartilage tube around the pterygoid hamulus then fans out within the soft palate and mingles with the fibers from the opposite side in the midline raphe V3
- 12. Attachment of Tensorveli palatini
- 13. Levator Veli Palatini inferioraspect of the petrous apex of the temporal bone Fanning out and blending with dorsal surface of the soft Palate related to the pumping clearance (drainage) function of the tube & Competence of the soft palate
- 14. Salphingopharyngeus muscle medial andinferior borders of the tubal cartilage via slips of muscular and tendinous fibers keep in position the pharyngeal orifice of the ET
- 15. The Eustachiantube (ET) is closed at rest. The opening of the ET is limited to Rüdinger’s safety canal. The lateral Ostmann’s fat pad transfers the pressure of the tensor veli palatini muscle to the ET. The function of the levator veli palatini muscle is restricted to the soft palate. The tensor veli palatini muscle has a dual function: opening the cranial portion and compression of the lower portion of the ET. The salpingopharyngeal muscle is an anchor chain of the cartilaginous part of the ET.
- 16. Endoscopic Anatomy • Medialend forms tubal elevation / torus tubarius • Lymphoid collection over torus is called Gerlach’s tonsil • Postero-superior to torus is fossa of Rosenmüller 16
- 17. 17 • Arterial supply:ascending pharyngeal & middle meningeal arteries • Venous drainage: pharyngeal & pterygoid venous plexus • Lymphatic drainage: retropharyngeal node
- 18. Nerve supply • Tubalmucosa – tympanic branch of cranial nerve IX • Tensor veli palatini - Mandibular branch of trigeminal • Levator veli palatini • Salpingo pharygeus Pharyngeal plexus 18
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- 23. Physiology of ET •Opens actively by contraction of tensor veli palatini & passively by contraction of levator veli palatini (it releases the tension on tubal cartilage) • Closes by elastic recoil of elastin hinge & deforming force of Ostmann’s fat pad
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- 25. 25 Functions of ET 1.Ventilation & maintenance of atmospheric pressure in middle ear for normal hearing. 2. Drainage of middle ear secretions into nasopharynx by muco-ciliary clearance, pumping action of Eustachian tube & presence of intra-luminal surface tension. 3. Protection of middle ear from :- – Ascending nasopharyngeal secretions due to narrow isthmus & angulation between 2 parts of E.T.at isthmus – Pressure fluctuations – Loud sound coming through pharynx
- 26. Sequence of eventsduring ET dilation A - ET at rest is closed. B - Proximal end of the cartilaginous lumen dilates first and is then followed by (C). C - dilation of the distal end and is open to the middle ear (ME). D - ET passively closes from the distal end to the proximal end to its resting, closed position
- 27. ET is shortand floppy in the infant crying insufflates nasopharyngeal gas into the middle ear compensate for their inefficient tubal opening mechanism But during periods of upper respiratory tract infection, nasopharyngeal secretions and viruses and bacteria—may also be insufflated into the middle ear
- 28. 28 Evaluation of eustachiantube function Aural fullness Pain and discomfort Hearing loss Tinnitus Dizziness
- 29. Pneumatic otoscopic examination •Positive pressure to the eardrum : TM move slightly inward (medially); • on releasing pressure on the pneumatic bulb TM will return to its original position
- 30. Endoscopic examination flexible fiberopticnasopharyngoscope inserted intranasally to examine the nasal cavities, nasopharynx, fossae of Rosenmüller, and pharyngeal orifices of the tubes.
- 31. • VALSALVATEST Principle :to build positive pressure in the nasopharynx so that air enter the Eustachian tube 31
- 32. Procedure of Valsalva: Patient pinches his nose with thumb and index finger Takes deep breath Closes his mouth Tries to blow air into the ears If air enters the middle ear the tympanic membrane will move outwards that can be visualized by otoscope
- 33. 33 • Inference : -Tympanic membrane perforation- a hissing sound - Discharge in the middle ear- cracking sound • Only 65% of persons can do this test • Contraindications : - atrophic scar of tympanic membrane which can rupture - infection of nose & nasopharynx
- 34. Politzer test • Donein children who are unable to perform valsalva test. • Olive shaped tip of the politzer’s bag is introduced into the patient’s nostril on the side of which the tubal function is desired to be tested. • Other nostril closed & the bag compressed while at the same time the patient swallows or says “ik,ik,ik” 34
- 35. • By meansof an auscultation tube a hissing sound is heard. • Compressed air can also be used instead of politzer’s bag • Test is also therapeutically used to ventilate the middle ear. 35
- 36. 36 Toynbee’s test • Usesnegative pressure • Ask the patient to swallow while nose is pinched • Draws air from middle ear to nasopharynx – inward movement of tympanic membrane visible otoscopically.
- 37. Negative middle-ear pressureafter the Toynbee test or only momentary negative middle-ear pressure followed by normal middle-ear gas pressure usually indicates good tubal function because it shows that the tube can open actively (the tensor veli palatini muscle contracts) and that the tubal structure is sufficiently stiff to withstand nasopharyngeal negative pressure.
- 38. Eustachian tube Catheterisation 38 Procedure Noseis anaesthetised ET catheter passed along the floor of nose till it reaches naso pharynx Rotated 90deg medially Pulled back till posterior border of nasal septum engaged Rotated 180 deg laterally – tip lies against tubular opening Politzer’s bag connected & Air insufflated Entry of air to middle ear verified (lateral bulging of t.m)
- 39. 39 Air pushed intoE.T.catheter by squeezing Politzer bag. Examiner hears by Toynbee auscultation tube put in pt's ear Inference :- Blowing sound = normal E.T.patency Bubbling sound = middle ear fluid Whistling sound = partial E.T.obstruction No sound = complete obstruction of E.T.
- 40. 40 Complications: • Injury toEustachian tube opening • Bleeding from nose • Transmission of nasal & nasopharyngeal infection into middle ear • Rupture of atrophic area of tympanic membrane
- 41. • Tympanometry (inflation-deflationtest) – +Ve & -ve pressures are created in the external ear and the patient swallows repeatedly – in patients with perforated or intact tympanic membrane • Radiological Test • Saccharine/ Methylene blue Test – Saccharine solution – Methylene blue dye – Ear drops into ear with TM perforation • Sonotubometry 41
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- 44. When the noseor nasopharynx is obstructed, unphysiologic pressures can develop in the nasopharynx and adversely affect the ET and middle ear, which is termed the Toynbee phenomenon.
- 45. Epidemiology / Causesof ET Dysfunction o Infants – short ET; immature immunity o Genetic & ethnicity o Craniofacial abnormalities – Downs; Cleft palate o Risk factors for inflammation- Passive smoking; air pollution; pacifiers; sleeping position; gastroesophageal reflux; cystic fibrosis; adenoiditis o Trauma – ET catheterisation; #maxilla o Neoplasm in nose and nasopharynx o Palatal paralysis
- 47. Reflux of nasopharyngealsecretions through the ET into the middle ear (ME) and draining out into the external auditory canal (EC)
- 48. Sequelae of ETdysfunction
- 49. Patulous Eustachian Tube •ET is abnormally patent • Causes: – Idiopathic, rapid weight loss, pregnancy (esp 3rd trim) & multiple sclerosis • Chief complaints – Autophony, hearing his own breath sounds • Pressure changes in the nasopharynx are easily transmitted to the ME • Movements of the TM can be seen with inspiration & expiration 49
- 50. The patulous tubeis open even at rest, which allows pressure regulation of middle-ear pressure, but sound pressures are transmitted to the middle ear, causing autophony
- 51. • Management – Acutecases: Usually self-limiting – Weight gain & oral administration of KI – Topical decongestants – Long standing cases: insertion of grommet; PET reconstruction ; injection of Vox implants. 51
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