1. Anatomy and Physiology of the Eustachian Tube Dr. Krishna Koirala

2. Links the pharynx to the middle ear Eustachius (1562) : Pharyngotympanic tube Antonio Valsalva : Eustachian tube Develops from tubotympanic recess which is derived from endoderm of 1 st pharyngeal pouch 36 mm long in adults Directed anteriorly, inferiorly and medially from anterior wall of middle ear forming angle of 45 0 with horizontal and sagittal planes Enters the nasopharynx 1.25 cm behind posterior end of inferior turbinate

4. Parts Lateral 1/3 - bony Medial 2/3 - fibro- cartilaginous Junction between 2 parts -- isthmus, narrowest part of Eustachian tube

6. Anatomy of medial 2/3rd Cartilage plate –Lies postero-medially –Consists of medial and lateral laminae separated by elastin hinge Fibrous tissue and Ostmann’s fat pad lie infero- laterally

7. Muscles 1. Tensor veli palatini or dilator tubae 1. Tensor veli palatini or dilator tubae 2. Levator veli palatini 2. Levator veli palatini 3. Salpingopharyngeus 3. Salpingopharyngeus 4. Tensor tympani 4. Tensor tympani Nerve supply 1. Sphenopalatine ganglion 2. Mandibular nerve 3. Tympanic plexus

9. Lining epithelium −Respiratory epithelium Arterial supply –Ascending pharyngeal & middle meningeal arteries Venous drainage −Pharyngeal & pterygoid venous plexus Lymphatic drainage −Retropharyngeal node

10. Endoscopic Anatomy Medial end forms tubal elevation / torus tubaris Lymphoid collection over torus is called Gerlach’s tubal tonsil Postero-superior to torus is fossa of Rosenmüller

11. Adult vs. Child (< 7 yr)

12. Adult vs. Children (< 7 yrs) ADULTINFANT Length36 mm18 mm Angle with horizontal45 0 10 0 LumenNarrowerWider Angulation at isthmusPresentAbsent CartilageRigidFlaccid Elastic recoilEffectiveIneffective Ostmann’s fatMoreLess

13. Physiology Bony part is always open Fibro-cartilaginous part closed at rest and opens on swallowing, yawning, sneezing Active opening by contraction of tensor veli palatini Passive opening by contraction of levator veli palatini ( ? releases the tension on tubal cartilage) Closure : Elastic recoil of elastin hinge and deforming force of Ostmann’s fat pad

14. E.T. opening

15. Functions 1.Ventilation & maintenance of atmospheric pressure in middle ear for normal hearing 2.Drainage of middle ear secretions into nasopharynx by mucociliary clearance, pumping action & 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

16. Functions

17. Conditions of Dysfunction

18. Bluestone’s Flask Model

19. Adult vs. Pediatric

20. TM perforation and nose blowing

21. O.M.E. & Barotrauma

22. Grommet insertion in O.M.E.

23. Tests for E.T. function

24. 1. Valsalva Maneuver Forced expiration with mouth & nose closed Otoscopy shows lateral bulging of Tympanic membrane

26. 2. Frenzel Maneuver Hands free Valsalva Compression of nasopharyngeal air by muscles of tongue Otoscopy shows lateral bulging of tympanic membrane

27. 3. Toynbee Maneuver More physiological Swallowing with mouth & nose closed Otoscopy shows retraction of tympanic membrane

28. Air pressure is alternately increased & decreased within external auditory canal Mobility of tympanic membrane is observed Normal mobility indicates good patency of Eustachian tube 4. Pneumatic otoscopy & Siegelization

29. Siegelization

30. Pneumatic Otoscope

31. Normal Tympanic Membrane

32. Eustachian Tube dysfunction

33. Early otitis media with effusion

34. Late otitis media with effusion

35. Acute suppurative otitis media

36. Ear drum perforation

37. 5. Politzerization Rubber tube attached to a Politzer bag put into one nostril and both nostrils are pinched Patient asked to swallow or repeat “k” Politzer bag is squeezed simultaneously Otoscopy shows lateral bulging of ear drum in patent Eustachian tube

40. 6. E.T. catheterization E.T. catheter passed along nasal floor till it touches posterior wall of nasopharynx Catheter rotated 90° medially & pulled forward till it impinges on posterior nasal septum Catheter rotated 180° laterally, & its tip inserted into opening of E.T. Politzer bag attached to outer end of catheter

41. Air pushed into E.T. catheter by squeezing Politzer bag Examiner hears by Toynbee auscultation tube put in pt's ear Blowing sound  normal E.T. patency Blowing sound  normal E.T. patency Bubbling sound  middle ear fluid Bubbling sound  middle ear fluid Whistling sound  partial E.T. obstruction Whistling sound  partial E.T. obstruction No sound  complete obstruction of E.T. No sound  complete obstruction of E.T.

42. Eustachian tube catheter

44. 7. Tymapanometry Type C = E.T. dysfunction Type B = fluid in middle ear

45. 200 mm H 2 O pressure is created in patient’s external auditory canal Patient asked to swallow 10 times Residual pressure in patient’s external auditory canal after 10th swallow is noted Test repeated with -ve 200 mm H 2 O pressure created in patient’s external auditory canal 8. William’s pressure equalization test

46. William’s Test Residual PressureResult Up to + 50 mm H 2 Onormal E.T. function + 51 to + 100 mm H 2 Omild dysfunction + 101 to + 199 mm H 2 Omoderate dysfunction + 200 mm H 2 Osevere dysfunction

47. 9. Sono-tubometry Sound made in pt’s nasal cavity & detected with stethoscope in patient’s external auditory canal Sound made in pt’s nasal cavity & detected with stethoscope in patient’s external auditory canal Loud sound = patent Eustachian tube Loud sound = patent Eustachian tube 10. Eustachian tube Salpingogram Dye instilled through E.T. catheter & X-ray taken Dye instilled through E.T. catheter & X-ray taken 11. C.T. scan & M.R.I. of skull

48. 12. Trans-nasal E.T. video-endoscopy 13. Test for E.T. patency in T.M. perforation Saccharine crystal / antibiotic ear drop / methylene blue placed in middle ear via ear drum perforation Saccharine crystal / antibiotic ear drop / methylene blue placed in middle ear via ear drum perforation Sweet taste / bitter taste / blue staining of secretions indicates patent Eustachian tube Sweet taste / bitter taste / blue staining of secretions indicates patent Eustachian tube

49. Patulous Eustachian Tube Aural fullness, humming tinnitus, autophony, hearing own breath sounds (tympanophonia) Symptoms resolve in supine position, in forward bending with head between knees, in U.R.T.I. and aggravated by mastication Otoscopy: T.M. moves during breathing Associated conditions: radiation therapy, hormonal therapy, nasal decongestants, 3 rd trimester pregnancy, stress, sudden weight loss, multiple sclerosis Treatment: Reassurance, weight gain, oral potassium iodide

50. Patulous Eustachian Tube Contd… Surgical interventions –Electro-cauterization of E.T. orifice –Peri - tubal injection with Teflon paste –Transposition of tensor veli palatini muscle medial to pterygoid hamulus –Plugging of E.T. orifice in Middle ear and myringotomy & grommet insertion