Otosclerosis

1. Otosclerosis Steven Powell SpR ENT

2. Outline Viva Questions Definitions Anatomy and Physiology Pathology Aetiology Clinical Features Diagnosis Treatment Options

3. Take Homes Exam! Cahart effect/ notch Multisided surgery Glasgow benefit plot

7. Paradoxes and questions Is otosclerotic bone sclerotic? Is a reparative granuloma a granuloma? Why aren�t people as grateful when you do the second side? How can the bone conduction be better than the air conduction in these patients?

8. Explain this

9. Definitions A localised hereditary disorder affecting endochondral bone of the otic capsule which is characterised by disordered resorption and deposition of bone.

10. Embryology Ectoderm forms otic pit and otocyst With neural crest cells forms membranous labyrinth Mesenchyme enclosing otocyst becomes chondrified to form otic capusle Ossification begins 16 weeks Dense bone- petrous Channels remain- oval window (footplate and annular ligament)

11. Anatomy

12. Anatomy

13. Anatomy Stapes Anterior crura, posterior crura, footplate Anterior crus thinner Stapedius inserts posteriorly into neck and posterior crus Footplate convex superiorly, straight inferiorly 3mm long, 1.4 mm wide Attached to bony margins by annular ligament

14. Physiology Middle ear is impedance matching system Higher impedance of fluid Size differential Lever action Couples sound preferentially to one window of cochlea

15. Bone Conduction- Cahart Effect

16. Pathology Normally very little remodelling of bone Bone remodelling (blasts and clasts) Active (spongiotic) areas Inactive (sclerotic) areas Commonest sites Anterior to oval window 80-90% Round window niche 30%

17. Histology

18. Pathology Clinical otosclerosis Histological otosclerosis Cochlear otosclerosis

19. Pathophysiology CHL Original thinking progressive air bone gap Bony ankylosis>otosclerosis>fibrous Now appears to be associated with stapedovestibular joint space Mucosa fibroproliferative Schwarte�s sign

20. Pathophysiology SNHL Otosclerosis in cochlear endosteum Action on spiral ligament Cytokine mediated Rare without cochlear otosclerosis

21. Pathophysiology SNHL

22. Epidemiology British Study of Hearing 2% M=F, but at CHL >30dB 3F:1M 10% prevalence in temporal bones, but ? selection

23. Aetiology Genetics Autosomal dominant, incomplete penetrance Sporadic COL1A1 gene defects Measles Autoimmune Biochemical factors Pregnancy

24. Clinical Features Decreased hearing Tinnitus (50-70%) May be no clinical signs Schwartze�s rare Normal TM Abnormal TM

25. Schwartze�s Sign

26. Investigations Pure tone audiogram Conductive hearing loss Mixed hearing loss Tympanometry CT MRI

27. Conductive Hearing Loss

28. Mixed Hearing Loss

29. CT

30. Differential Diagnosis Congenital ossicular abnormalities Ossicular fixation Ossicular errosion Ossicular dislocation Tympanosclerosis Osteogenesis imperfecta type 1!

31. Management Options Watch- natural history Conventional hearing aids BAHA Cochlear implant Stapes surgery Fluorides

32. Hearing Aids 4 scenarios Primary treatment CHL Mixed hearing loss Combination after surgery to reduce CHL to serviceable level Rescue treatment BAHA Cochlear implant (not a hearing aid)

33. History of Surgery 1876 Kessel- removed footplate 1888 Boucheron- rocked footplate Fell into disrepute 1938 Lempert- Fenestration 1952 Rosen- Mobilisation 1956 Shea- stapedectomy and prosthesis

34. Surgery Used to be threshold of 20dB gap for operating, but now CHL of 10dB may be operated on Contraindictions Pregnancy Active infection

35. Surgery Anaesthesia general v local Per-meatal or endaural Tympanomeatal flap Curette bone Assess ossicular chain Measure distance

36. Surgical Techniques- stapedotomy

37. Stapedotomy Techniques Drill Lasers Tissue to seal- vein Type of piston Size of piston

38. Surgical Techniques- Stapedectomy

39. CT

40. Surgical Problems Floating footplate Obliterated footplate CSF gusher Facial nerve dehiscence/ prolapse

41. Post-Operative Complications Conductive Hearing Loss Displacement of Prosthesis Necrosis LPI Bony regrowth

42. Postoperative Complications Sensorineural hearing loss- rates vary depending on paper 1-10% Extensive drilling Floating footplates Perilymph leak Delayed SNHL

43. Post- Operative Complications Facial nerve injury Vertigo Perilymph fistula Reparative granuloma Discomfort to noise Taste changes Cholesteatoma Meningitis

44. Stapedectomy v stapedotomy Stapedectomy Better low frequency hearing gain Stapedotomy Better HF gain Lower incidence: perilymph fistula, SNH impairment, post-op vertigo, revision surgery

45. Surgical Issues Unilateral Second side surgery

46. Glasgow Benefit Plot

47. Belfast Rule of Thumb Operated ear brought to 30dB or better or within 15dB of contralateral ear

48. Revision Surgery 92% for CHL 2% dizziness/ SNHL/ fistula More problems Adhesions Ossicular problems Higher risk SNHL

49. Paradoxes and questions Is otosclerotic bone sclerotic? Is a reparative granuloma a granuloma? Why aren�t people as grateful when you do the second side? How can the bone conduction be better than the air conduction in these patients?

50. Questions Otosclerosis is only partially sclerotic. A larger part may be spongiotic A reparative granuloma is a misnomer and is granulation tissue �Over correction� of the air bone gap is explained by the Cahart effect Second side surgery often doesn�t improve overall hearing level as demonstrated by Glasgow Benefit Plot

51. Summary Otosclerosis is a disorder of bone resorption and deposition in the otic capsule bone/ petrous temporal bone Its commonest manifestation is conductive hearing loss +/- sensorineural loss Treatment options of aiding versus surgery should be weighed up in context of the audiometry, contralateral ear and patient preference.

52. Thankyou