Eustachian Tube - Anatomy physiology and Disorders UG.pptx

prepared this presentation for undergraduate MBBS students. Please go through this and provide your valueable suggestions to improve . Thank You Dr Diwash Sunar MBBS, MS - ENT (AIIMS, New Delhi) Lecturer - Birat Medical College Teaching Hospital [email protected]

1. Anatomy, Physiology and Disorders of Eustachian Tube Dr. Diwash Sunar MBBS (Manipal, KU) MS – ENT Head & Neck Surgery ( AIIMS, New Delhi ) Lecturer – BMCTH, KU

2. Learning Objectives Anatomy of the Eustachian Tube Anatomy Adult v/s Pediatric Physiology of the Eustachian Tube: Disorders of the Eustachian Tube: Identify common disorders associated with the Eustachian tube Tests to evaluate the function of Eustachian tube

3. Pre - Test

4. Eustachian Tube (ET) Also called “ Auditory Tube” / “Pharyngotympanic Tube ” 31-44mm long Oseteo-cartilagenous canal (mean 36mm ) Lateral 1/3 rd (12mm)is bony and medial 2/3 rd (24mm) is fibrocartilaginous Connects anterior mesotympanum with lateral wall of nasopharynx (1.25 cm behind the posterior end of Inferior Turbinate) Bony cartilaginous junction is the narrowest part of ET – known as Isthmus

5. The bony part of ET lies completely within the petrous part of the temporal bone. Torus tubarius is the posterior and superior elevated mucosal part around nasopharyngeal opening Ostmann’s fat pad lympho-adipose body, situated around the pharyngeal end in the inferolateral aspect. It occupies the space between the ET proper and the TVP muscle . It contributes to the protection of the ET and the middle ear from reflux of nasopharyngeal secretions. In malnourished persons this pad of fat is lost causing patulous ET.

6. Direction of ET – Downward, Forward and Medially ET is lined by pseudostratified ciliated columnar epithelium Tensor veli palatini, Levator veli palatini and Salpingopharyngeus muscle attach to the cartilaginous part

7. Blood supply : ET receives blood supply from Ascending pharyngeal Artery and Middle meningeal arteries Venous drainage - The Pharyngeal and pterygoid venous plexus Retropharyngeal lymph node is the draining lymph node.

8. Muscles of the Eustachian Tube 4 muscles are associated with the ET: Tensor veli palatini (TVP) Levator veli palatini (LVP) Salpingopharyngeus Tensor tympani ET is closed at rest and opens during swallowing or yawning Active opening of the ET is induced by TVP muscle contraction Closure of the tube is a passive phenomenon. - It takes place secondarily to the passive reapproximation of the tubal walls by extrinsic forces exerted by the surrounding tissues and also by the recoil of elastic fibers of the hinge portion.

9. Eustachian Tube mucosa The lumen of ET - lined by a pseudostratified, columnar epithelium of a ciliated type , which sweeps material from the middle ear to the nasopharynx. The mucosa is continuous with the lining of the tympanic cavity at its distal end, as it is with the nasopharynx at its proximal end. Associated with these ciliated epithelial cells are the goblet cells figuring about 20 % of the cell population

10. The floor mucosa of the tube - numerous goblet cells, copious ciliated cells, and glands The roof mucosa of the tube - less goblet cells and cuboidal ciliated cells without seromucous glands. 2 different morpho-functional corridors in the ET lumen: 1. Superior corridor: the roof for the ventilation function 2. Inferior corridor: the floor with its mucociliary clearance function

11. ET is relatively straighter, smaller (18-21mm) and much wider in children. Angle is 10 degree in children, whereas 45 degree in adult with horizontal plane Natural anatomy of flaccid cartilage in children make ET vulnerable to retrograde refulx Infant v/s Adult ET

12. Anatomical differences of the Eustachian tube between infants and adults

13. Nerve supply of ET cartilagenous portion of the ET - pharyngeal branch of the sphenopalatine ganglion deriving from the M axillary nerve (V2) bony portion of the ET - Tympanic plexus deriving from the glossopharyngeal nerve (IX)

14. PHYSIOLOGY Lumen of ET allows the passage of 2 different physical substances: Gaseous - for middle ear ventilation fluid - for the middle ear clearance The bony portion is patent at all times; fibrocartilaginous portion is closed at rest and opens intermittently. Brief intermittent periods of ET opening occur in normal individuals to ensure middle ear ventilation. The ET opens 1.5 times every minute. Every opening lasts about 0.5 seconds These openings are the result of the contractions of TVP muscle Due to its reduced caliber , this segment plays a protective role for the middle ear against recurrent otitis media in preventing nasopharyngeal secretions to enter the middle ear cavity. Nasopharyngeal end is closed in resting condition The contraction of palatini muscles and salpingopharyngeus muscles (Yawning and swallowing) opens ET

15. FUNCTIONS OF EUSTACHIAN TUBE Middle Ear pressure equalization with atmospheric pressure Protection of Middle ear from pressure fluctuation at the nasopharynx level Drainage of middle ear secretions Poor functioning of ET generates Negative middle ear pressure, which leads to retraction of tympanic membrane, and collection of fluid in middle ear

16. ET DISORDERS

17. ET Dysfunction The factors for malfunctiong of ET is divided into 3 types 1. Functional obstruction - when ET is persistently closed ( Cleft Palate ) 2. Mechanical obstruction ( Adenoiditis , Obesity, Nasopharyngeal mass ) 3. Inflammation – intrinsic cause of dysfunction ( URTI, Smoking )

18. It is one of the common problem in paediatric age group, especially in winter season Bottle feeding and incorrect feeding position are the risk factors. Breastfeeding has a much lesser chance of infection than bottle feeders, because of protective effect of breast milk.

19. Predisposing / Risk Factors for ET dysfunction URTI Rhinosinusitis Allergy Enlarged adenoids, nasopharyngeal mass, tumors Cleft palate Down syndrome Smoking Radiation exposure GERD

20. In Cleft Palate – ET dysfunction is due to Abnormalities of Torus Tubarius as TVP does not insert into the torus tubarius Otitis media with effusionis the most common finding in such patients

21. In Down Syndrome – ET dysfunction is due to Poor tone of TVP and abnormal shape of Nasopharynx.

22. Symptoms of ET dysfunction Ear fullness Ear pain Tinnitus Hearing loss # hearing evaluation reveals N egative Rinne's test Lateralization of Weber test on the side of ET Dysfunction.

23. Impairment of the ET function can be divided into two main categories: Eustachian tube dysfunction when the tube does not open properly or patulous Eustachian tube when the tube remains inappropriately patent.

24. Eustachian Tube Dysfunction (ETD) ETD is result of mucosal inflammation with edema and obstruction, or anatomical extrinsic obstruction Dilatatory dynamic dysfunction of the ET is a strong contributor for ET disorders in infants. Anatomical extrinsic obstruction must always be ruled out. In children and adolescent, anatomical obstruction could be frequently due to adenoid hypertrophy . In adults presenting unilateral ET dysfunction, nasopharyngeal tumors must be ruled out Intrinsic blockage of the ET is more common than anatomical extrinsic obstruction. It is often the result of mucosal inflammation (mucosal disease), possibly due to allergies or laryngopharyngeal reflux. Tobacco use results in a loss of the normal ciliary clearance of the mucosa and causes frequently ET dysfunction.

25. Patulous Eustachian Tube Patulous ET occurs when the ET tube remains patent for prolonged time beyond the normal brief interval of opening This condition could be related to Ostmann’s fat pad atrophy that may develop after substantial weight loss or post-pregnancy. Patients with patulous ET typically complain of A utophonia and Aural fullness . When patients lie down, the symptoms usually abate due to venous engorgement of ET mucosa.

26. Tests for ET Dysfunction No diagnostic test is proposed as a gold standard for diagnosing ETD. combination of tests + clinical features establishes the diagnosis.

27. 1. Valsalva's Maneuver The creation of positive nasopharyngeal pressure increases middle ear pressure by blowing against closed nostrils and lips. The force is transmitted to the middle ear via the ET, pushing the tympanic membrane outward. TM perforation – hissing sound Middle ear discharge – Crackling sound Only 60-65% people can do this test Contraindications : Atrophic scar of TM  TM can rupture Infection of nose / nasopharynx

28. 2. Toynbee's Maneuver The negative middle ear pressure is generated by creating negative nasopharyngeal pressure by swallowing against closed lips and nostrils. The otoscopic examination shows the inward movement of the tympanic membrane.

29. 3. Frenzel's Maneuver It is more effective than the above maneuvers . Nasopharyngeal pressure is further increased by convexing the posterior tongue superiorly. (blow after touching palate by tongue) 4. Politzer's Test It is the perception of sound on auscultation of the external ear by modifying the pressure in the nostril by Politzer bag.

30. 5. Eustachian Tube Catheterization The Eustachian tube catheter is passed along the floor of the nasal cavity to the nasopharynx. The catheter is turned medially by 90° and pulled forward till it hinges behind the nasal septum, then turned 180° laterally. The catheter lies opposite the ET opening. Politzer bag is attached with a catheter, and the air is insufflated . The air entry sound can be heard by auscultation of the external ear. The bulging tympanic membrane can be observed on otoscopy.

31. Complications : Injury to ET opening bleeding Transmission of nasal and nasopharyngeal infection into middle ear Rupture of atrophic areas of TM

32. 6. Impedance Test (Tympanometry) It is the most commonly employed test for Eustachian tube function assessment. The C type of reflex is observed in ET dysfunction (peak at negative pressure)

33. 7. Nasal Endoscopy and Radiology It may help document the obstructive type of ETD. Nasal endoscopy is good enough to establish the cause of Eustachian tube dysfunction in cooperative patients. X-ray nasopharynx is required in uncooperative and young patients to check the hypertrophy of adenoids. CT scan is needed in selected cases.

34. Management of Eustachian Tube Dysfunction The treatment of ETD is correcting causative factors ( eg;adenoidectomy , cleft palate repair, cholesteatoma excision with tympanoplasty)