OTOSCLEROSIS

1. OTOSCLEROSIS Dr.Nayana V G Senior Resident YMC

2. Anatomy of ear

3. CONDUCTION

4. INTRODUCTION • Otosclerosis – “Hardening of the ear” • Primary & exclusive disease of otic capsule (bony labyrinth and footplate of stapes) • Characterized by alternate phases of bone resorption and formation. • Mature lamellar bone is removed by osteoclasis & replaced by woven bone of greater thickness cellularity & vascularity

5. Seen exclusively in humans. • Clinical otosclerosis-location of bony changes or its secondary effects results in evident clinical manifestations. • Histological otosclerosis-bony changes are present, but not clinically manifested.

6. OTOSCLEROSIS -HISTORY • ANTONIO VALSALVA (1735) First descriptions of ankylosisof stapes to margins of oval window. • VON TROLTSCH. (1881) Coined the term otosclerosis. • JOHN J SHEA –described the operation of stapedectomy in 1958

7. EMBRYOLOGY-OTIC CAPSULE 4 wks– otic capsule arises from mesenchyma surrounding otic vesicle. 8 wks- cartilaginous framework is begun. 16 wks– absorption of cartilage occurs & ossification begins from 14 centres which fuses to form a single bony box without the presence of a single suture line. BONY LABYRINTH , FOOTPLATE OF STAPES

8. REGIONS WHERE RESIDUAL CARTILAGE NOTED Fissula ante fenestram Fissula post fenestram Enchondral layer of cochlea Round window SCC.

9. LAYERS OF BONY LABYRINTH • ENDOSTEAL– innermost layer lining bony labyrinth formed by internal perichondrium. • ENCHONDRAL–middle layer which develops from the cartilage & later ossifies into bone. • PERIOSTEAL- outer layer which adds bulk to the otic capsule. ( islands of cartilage left unossifiedin the enchondral layer later give rise to otosclerosis)

10. STAPES - ANATOMY • Head, ant.crura, post.crura & footplate. Footplate is a thin oval osseous platform attached by annular ligament to margins of oval window. Footplate normally-blue In otosclerosis-white

11. OTOSCLEROSIS-ETIOLOGY • UNCLEAR; multiple theories available. • Unstable rests of embryonic cartilage within the labyrinthine capsule > immune reaction > recruitment of inflammatory monocytes > enzyme activity. • Type ll collagen autoimmunity. • Hereditary factors – autosomal dominant with incomplete penetrance(40%); also associated with abnormalities in COL1A1 gene.

12. Endocrinologic factors – more in women; pregnancy and menopause seems to stimulate activity in otosclerosis. • Infections – measles virus • Changes in vascularity • Associated with pagets disease and osteogenesis imperfecta.

13. EPIDEMIOLOGY • AGE -20 to 30yrs; youngest – 6 yrs • SEX – male:female – 1:2 (histologic otosclerosis – 1:1 ) - b/lotosclerosis – women - asymmetric deafness- men

14. RACE – white > black.- Caucasian – 15% - Asian -10% - African American -1% - Native American -0% • Nonclinical otosclerosis is seen 10 times more common than clinical.

15. STAPEDIAL • COCHLEAR • HISTOLOGIC

16. Stapedialotosclerosis • Commonest variety causing stapes fixation and COHL ANTERIOR FOCUS-lesionstarts just in front of oval window. POSTERIOR FOCUS-lesion starts behind the oval window. CIRCUMFERENTIAL-around the margin of stapes footplate.

17. BISCUIT TYPE in the footplate ;but annular ligament being free OBLITERATIVE- completely obliterate the oval window niche

18. Cochlear Otosclerosis • Involves region of round window or other areas in the otic capsule and cause SNHL. • Possible causes of cochlear degeneration are 1) Bony invasion of scala tympani 2) Circulatory changes- venous obstruction in the basal turn of the cochlea by otosclerotic bone -> incompetence of the venous drainage of the anterior and middle spiral veins 3)Toxic metabolites from abnormal bones. Mainly 6 enzymes-alpha –chymotrypsin, LDH, ribonuclease, acid phosphatase, collagenase and trypsin

19. COMMON SITES • 3Area in front of oval window-commonest(80%) • Round window- 2nd most common. • Other sites- apical medial wall of the cochlea, posterior to oval window, the posterior IAC, cochlear aqueduct and semicircular canals.

20. HISTOLOGY(Early phase and late phase) • EARLY PHASE lesion consist of osteoclasts(most active),histiocytes, osteoblasts etc . osteoclasts cause bone resorption around preexisting blood vessels -> widening of vascular channels and widening of micro circulation -> reddish hue through an intact TM if active focus reaches promontory (SCHWARTZE SIGN).

21. HISTOLOGY CONTD.. • EARLY PHASE Areas becomes rich in amorphous ground substance &deficient in mature collagen resulting in formation of new spongy bone. Spongy bone appears densely blue in h-e staining blue mantles of manasse Foci of peri vascular bony invasion coalesce and enlarge within otic capsule ( otospongiosis )

22. HISTOLOGY CONTD.. • LATE PHASE -formation of dense sclerotic bone in areas of previous bony resorption. - dilated vascular spaces are narrowed due to dense bony deposition. ( although otosclerosis begin in enchondral bone , as spongiosis & sclerosis continue , the endosteal and periosteal layers get involved as well.)

23. CLINICAL FEATURES Young female Slowly progressive b/l hearing loss over a period of many yrs. Worsened during pregnancy Positive family history of hearing loss &its surgical correction70% Negative history for infections or trauma as a possible cause of conductive HL. Monotonous, well modulated soft speech.

24. HEARING LOSS CONDUCTIVE HL(stapedialotosclerosis) -70% bilateral -noticed by around 20-30 yrs -slowly progressive -better hearing in presence of background noise-Paracusiswillisi unilateral COHL –less noticed; pts have difficulty in direction of sound SNHL(cochlear otoslerosis) Mixed HL (combined variety)

25. TINNITUS Present in about 75%. U/l or B/l. Roaring , hissing or pulsatile character. Indication of sensorineural degeneration . Also as a result of abnormal degree of vascularity of otosclerotic bone in pts without cochlear degeneration. More common in early stages & may disappear as the lesion matures.

26. VERTIGO In about 25%. Usually of transient nature. Due to action of toxic enzymes on vestibular labyrinth and vestibular hydrops secondary to cochlear otosclerosis.

27. SIGNS Otomicroscopy TM is normal in most of the pts. Schwartze’s sign /flamingo flush – red blush over promontory or area ant to oval window - + in about 10%. Tuning fork tests Rinne -ve with 256, 512 &1024 as disease progress. Weber lateralizes depending upon degree of conductive(towards worser ear) &sensorineural HL (towards better ear). ABC – normal or decreased in SNHL.

28. INVESTIGATIONS Key objective measurement Characterizes the severity of disease Hallmark – slowly widening air-bone gap beginning in low frequencies.(increase in annular ligament stiffness first affect low frequency response of the ear) COHL range from 5 – 60 dB depending on stapes fixation Variable degrees of SNHL may also be present.

29. Carhart’s notch 20-30 dB loss of bone conduction at 2000 Hz Highly characteristic of otosclerosis Actually reflects the elimination of middle ear contribution to bone conducted hearing rather than a loss in cochlear sensitivity. Usually disappears after successful stapedectomy. .

30. Investigation….. TympanogramNormal in early cases ; As type curve in ossicular fixation. Computed tomography (CT) of the temporal bone EARLY PHASE –radiolucent area in &around cochlea LATE PHASE – diffuse sclerosis

31. TREATMENT MEDICAL HEARING AIDS SURGICAL COMBINATIONS

32. TREATMENT Observation:- In unilateral & Bilateral CoHL with 30-40dB (if it does not hamper job performance)patient to be followed up once in every 6 to 12 months. Amplification:- Low grade hearing aid for mild to moderate HL. Patients who cannot undergo surgery Advanced otosclerosis After stapedectomy. In profound hearing loss cochlear implantation can be considered.

33. MEDICAL TREATMENT To mature involved bone & decrease osteoclastic actiivity. SODIUM FLOURIDE:- Mechanism of action:-flourine comes in contact with bone , F ion replacing the hydroxyl ion in bone -> Flouroapatite complex is much more stable than hydroxyapatite crystals found in normal cells. Lead to positive ca++ balance

34. Indication of NaF Therapy • Patients with OS shows progressive SNHL disproportionate to the age. • Cochlear otosclerosis • Pt’s with radiological demonstration of spongiotic lesion on cochlear capsule. • Positive Schwartze sign. • Post operatively with active foci, NaF can be given.

35. Chronic nephritis& nitrogen retention. • Chronic rheumatoid arthritis. • Pregnancy & lactation. • Allergic to flouride. • Patients with skeletal flourosis. • In children before full skeletal growth has been completed. • Oral NaF 30 to 120 mg daily • Combined with 400units of vitaminD& 10mg of CaCo3 daily.

36. Surgical management • Stapedectomy • Stapedotomy Surgical Goal in otosclerosis is restoration of the transmission mechanism for sound from TM through ossicular chain to OW bypassing resistance of fixed stapes.

37. Stapedectomy Stapedectomy is the treatment of choice for the conductive component of otosclerosis. This is a technique of stapes extraction with tissue coverage of OW & polyethylene strut reconstruction of stapes.

39. STAPEDOTOMY Surgical development of small fenestra placed centrally in the stapedial foot plate A small fenestra of 0.8mm placed centrally on FP A piston prosthesis is inserted to a depth of 0.25mm in the vestibule. Piston crimped to the long process of incus. A tissue seal made around the piston Stapedotomy may also be performed by using laser,Co2 laser provides precise control& less complications.

41. SUMMARY Hearing loss in OS is progressive CoHL that begins in 20s & progress to mild, moderate or rarely severe hearing loss with SNHL component. Surgery for OS evolved over the past 70yr to a safe & effective method of restoring hearing Complications are rae. O.P procedure under LA. Hearing aids & medical management can be a option for pt not choose/fit to have surgery.