ENT

1. ENT Ear Nose Throat

2. Otologic Surgery-Anatomy

3. External ear- Auricle (pinna) • Concentrates sound waves and conducts them into the external auditory canal • Flexible cartilage covered with thick skin • One on each side of head helps judge direction of sounds • Shape of auricle helps differentiate between sounds in front or back

4. External auditory canal • S-shaped pathway about 2.5 cm long • Made up of bone and cartilage, covered by soft, sensitive skin • Cerumen- waxy substance • Protects and lubricates canal • Secreted by sebaceous glands in the distal third of the canal • Helps trap foreign materials and reduce bacterial levels

5. Tympanic Membrane (eardrum) • Comprised of three layers • Outer layer- epithelium • Middle layer- fibrous connective tissue • Inner layer- mucous membrane • Is disc shaped, concave, translucent gray, with a diameter of about 1 cm • Protects the middle ear

6. Middle ear • Filled with air from the nasopharynx via the Eustachian tube • Communicates with the mastoid air cells of the temporal bone

7. Middle ear

8. Middle ear • Mucous membrane of the middle ear is continuous with that of the pharynx and mastoid cells, making it possible for infection to travel to the middle ear (otitis media) and the mastoid cells (mastoiditis)

9. Middle ear • Ossicles- a chain of 3 tiny, moveable bones that extend across the middle ear, from the tympanic membrane to the oval window • Malleus (hammer) • Incus (anvil) • Stapes (stirrup) • Moveable joints allow the ossicles to transmit sound across the middle ear

10. Conduction • Tympanic membrane • Malleus • Incus • Stapes • Oval window • Fluid of cochlea • Round Window • Hair Cells of the organ of Corti

11. Middle ear • Oval window- an oval shaped aperture in the wall of the middle ear leading to the inner ear. The footplate of the Stapes vibrates in the oval window, transmitting sound waves to the cochlea.

12. Middle ear • Round window- below the oval window. Round opening in the medial wall of the middle ear leading into the cochlea and covered by a membrane called the secondary tympanic membrane

13. Inner ear (labyrinth) • Bony labyrinth • Membranous labyrinth

14. Inner ear (labyrinth) • Bony labyrinth- filled with watery fluid (perilymph) that surrounds and bathes the membranous labyrinth • 3 divisions • Cochlea • Vestibule • Semicircular canals

15. Inner ear (labyrinth) • Cochlea- tubular shaped, resembling a snail shell • Organ of Corti- neural end organ for hearing • Neuroepithelium- projects thousands of hair cells that convert the wave motion into electrochemical impulses • Connected to the brain by the 8th cranial nerve (vestibulocochlear or acoustic)

16. Inner ear (labyrinth) • Vestibule-contains 2 sacs, utricle and saccule, which are gravity oriented and concerned with static equilibrium • Semicircular canals- 3- lateral, superior, and posterior canals, at approximate right angles to each other • Controls equilibrium during movement

17. Inner ear (labyrinth) • Membranous labyrinth- within it lie four (4) structures: the cochlear duct, utricle, saccule, and the semicircular ducts • Endolymph bathes and nourishes the sensory cells contained within the membranous labyrinth

18. Conduction • Tympanic membrane • Malleus • Incus • Stapes • Oval window • Fluid of cochlea • Round Window • Hair Cells of the organ of Corti

19. Ménière’s disease • Recurrent and usually progressive group of symptoms including: • Progressive deafness • Ringing in the ears • Dizziness • Sensation of fullness or pressure in the ears • Attacks occur suddenly and may last as long as 24 hours

20. Ménière’s disease Normal Membranous Labyrinth Dilated Membranous Labyrinth in Ménière’s disease (Hydrops)

21. Ménière’s disease • When one ear is affected, the other will also become involved in approximately 50% of cases • Etiology is unknown, but edema of the membranous labyrinth has been found in autopsies • TX- bed rest, antihistamines, sedatives, discontinuation of smoking, and, rarely, surgery

22. Considerations • Gloves must be powder free to prevent granuloma formation, which could lead to irreversible hearing loss • Operating microscope is used routinely, and handles or a drape will be needed

23. Considerations • Pass instruments in a manner to allow the surgeon to remain focused on the operative site • Instruments are delicate, and must be handled carefully to avoid damage

24. Considerations • When using a burr to remove bone constant irrigation is needed to combat heat buildup and bone dust accumulation

25. Considerations • Multiple suction tips must be available, as they are so fine they clog frequently • A nerve stimulator should be available • Hemostasis may be accomplished with epinephrine, gelfoam or bone wax

26. Anesthesia • Local anesthesia may be used for minor procedures on the external ear, or for procedures in which the doctor wants to test the patients hearing during the procedure

27. Anesthesia • General anesthesia is used to prevent patient movement on procedures involving the fine structures of the middle or inner ear

28. Anesthesia • In the absence of inflammation the mastoid bone lacks sensation, except for the outer periosteum, so a local anesthetic may be used

29. Positioning • Patient should be supine with the operative ear up • Dependent ear should be protected from pressure with a donut or similar headrest

30. Prep • Hair may be shaved or clipped if necessary, and/or plastic drapes may keep the field free from hair • Prep the auricle and periauricular skin • Meatus may be prepped with a swab if the eardrum is not perforated

31. Draping • Should be lint free to prevent granuloma formation • Plastic aperture drapes are common, and may be placed before or after the prep • Triangle off with 3 towels, and a fenestrated drape may be placed • Split sheets may also be utilized

32. Incisional approaches • Endaural- incision is made near the meatus • Offers direct access to the canal and tympanic membrane, or for stapes surgery

33. Incisional approaches • Transcanal- incision is made in the tympanic membrane, through the canal • For surgery on the tympanic membrane or the ossicles

34. Incisional approaches • Postauricular- incision is made behind the ear, following the posterior auricular skin fold • Used for procedures on the mastoid, middle, and inner ear

35. Surgical interventions

36. Myringotomy • Incision of the tympanic membrane, usually with placement of pressure equalization (PE) tubes • Performed to treat acute otitis media, when the exudate does not respond to antibiotic therapy • Common pediatric problem

37. Myringotomy There are a variety of PE tubes to choose from, depending on the length of time the doctor wants them to stay in.

38. Myringotomy • Care must be taken to avoid getting water in the ears while the tubes are in place • Myringotomy knife, alligator forceps, and microscope • Once the tube falls out, the incision usually heals

39. Tympanoplasty • Surgical repair of the tympanic membrane • Usually for perforation of the ear drum resulting from direct injury, blow to the ear, tears from temporal bone fractures, and lightning injury

40. Tympanoplasty

41. Tympanoplasty • Most common serious ear injury necessitating surgical intervention • Conductive hearing loss, as it may disturb ossicular continuity • Repaired using a graft (dried temporalis fascia or synthetic)

42. Mastoidectomy • Removal of diseased bone of the mastoid process, along with the cholesteatoma present in the middle ear and the mastoid • Cholesteatoma- a cystic mass composed of epithelial cells and cholesterol that is found in the middle ear.

43. Mastoidectomy

44. Mastoidectomy • Cholesteatoma- • Occurs as a congenital defect or as a serious complication of otitis media • The mass may occlude the middle ear, or enzymes produced by it may destroy the adjacent bones, including the ossicles

45. Mastoidectomy • General anesthesia usually, but can use local • Postauricular or endaural incision • Use a burr to remove diseased bone • Simple mastoidectomy- removal of the air cells

46. Mastoidectomy • Modified radical mastoidectomy- removal of the air cells and the wall of the external ear canal, preserving the ossicles

47. Mastoidectomy • Radical mastoidectomy- removal of the mastoid air cells, along with the tympanic membrane, malleus and the incus. • Stapes usually remains in place, and is covered with a temporalis fascia graft

48. Stapedectomy Removal of the stapes for otosclerosis, and replacement with a prosthesis to restore ossicular continuity and alleviate conductive hearing loss

49. Removal of Acoustic Neuroma • Benign tumor of the acoustic nerve • Symptoms may include tinnitus, progressive hearing loss, headache, facial numbness, dizziness • Typically slow growing

50. Removal of Acoustic Neuroma • Proximity to the cranial nerves and the brainstem make them dangerous intracranial lesions • Ideal TX is total removal of the tumor • Postauricular incision