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OTOSCLEROSIS
Lecture
BY Dr Mazhar
Iftikhar
Anatomy
Otic Labyrinth Periotic Labyrinth Otic Capsule
Definition
Primary localized disease of bony otic capsule
Irregular spongy bone replaces dense enchondral bone
Characterised by; Spongy bone Hearing loss
Aetiology
Anatomical basis Hereditary 50% Race white> negroes Sex females> males Age of onset 20 - 30 Autoimmune type II collagen Measles virus antibodies
Incidence
Clinical otosclerosis upto 3.5%
Histological otosclerosis upto 13%
Pathology
Grossly; Chalky white May be Red /inc vascularity Spongy bone
Histopathology
Globuli Interossei Areas of;
Bone resorption New bone formation Vascular proliferation Connective tissue stroma
Spongiotic bone
Distribution of lesion
Anterior to oval window 90% Round window 30% Cochlear labyrinth 25% Stapes footplate 12% Posterior to oval window 5-10%
Pathology of CHL
Conductive hearing loss 5-60 dB
Expansion to ant of oval window 30-40dB
Bony ankylosis >40dB Narrowing & impairment of annular
lig at post stapediovestibular joint
Pathology of SNHL
Subject of much controversy Atrophy /Hylinization of spiral
ligament cytokines
Pathology of vestibular symptoms
Scarpa’s ganglion Soluble toxic substances Direct invasion
Symptomatology
Slowly progressive hearing loss Apparent at 25 – 30 dB loss
Paracusis Willisii Characteristic soft speech Tinnitis Dizziness & vertigo rarely
Physical Exam
Careful Otoscopic Exam Microscopic Exam
Rule out other causes Tympanic memb normal Middle ear pneumatized Reddish blush (schwartze sign )
Classic Audiometric Findings
Negative Rinne test Low frequency CHL Carhart notch Type A/As tympanogram Diphasic or absent reflexes
Imaging Studies
CT Scanning MRI
Treatment
A. Observation
Least risky Least expensive When no intervention recquired Audiogram on yearly basis
B. Nonsurgical Measures.
1. Sodium Flouride Therapy Reduces bone resorption Inc bone formation Inhibit proteolytic enzymes
2. Bisphosphonates Anti resorptive/inhibit osteoclasts
B. Nonsurgical Measures
3. Amplification Conventional hearing aid Bone-anchored hearing aids
C. Surgical Measures
Indications Air conduction level 45 – 65 dB Bone conduction level 0 – 25 dB Air-Bone Gap 15 dB Discrimination score >60%
Surgical technique
Anaesthesia Tympanomeatal flap raised Ossicular chain inspected & palpated Divisionh of stapedius tendon Crurectomy Stapedotomy Insertion of prothesis & packing
Recent Advances
LASER use Cochlear Implantation
Revision Surgery
Encourage to use hearing aids Failure may be due to
Incus erosion Poorly positioned prosthesis Mallius or Incus fixation Reobliteration
Prognosis
Immediate success Decline slowly After Stapedotomy 3dB decline per
decade After stapedectomy 9dB decline
per decade
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