Otosclerosis typically begins at

Ans. d (Fistula antefenestrum) (Ref. Bhargava ENT 6th ed., p 76; PL Dhingra, 3rd ed., p 114)# in otosclerosis, the oval window is involved in 85% of cases and the round window in 15%, respectively, with otosclerosis and conductive deafness.# Infact, the commonly involved site is the anterior oval window region {fistula ante fenestrum).OTOSCLEROSIS# Introduction:- Otosclerosis (otospongiosis) refers to a condition where the enchondral bone around the otic capsule is replaced by multiple foci of spongy vascular irregular bone. The spongy bone later becomes calcified and sclerotic.# Etiology & location:- 70% familial, autosomal dominant. 0- F: M - 3: 1; more common in pregnancy.- Age of onset 20-30 yrs- White races.# Clinical features:- Deafness, conductive (in cochlear, sensorineural loss is present), Tinnitus.- Ear drum: Normal- In active otosclerosis, pink patch (Flamingo tint) present over promontory (Schwartz Sign), i.e., Schwartz sign is =>Red hue may be seen through the tympanic membrane of promontory.- Paracusis Willisi (Patient hears better in noisy surroundings) 0- Depression in audiogram and Carhart's notch. 0- Reduced compliance at ambient pressure, i.e., type As tympanogram is diagnostic. Q# CT scan:- Otosclerosis is divided into two types:# Fenestral Otosclerosis- Fenestral otosclerosis is the most common form and involves the oval window and the footplate of the stapes. Imaging Finding is a subtle bony rarefaction at the anterior wall of the oval window.# Retrofenestral (Cochlear) Otosclerosis- It presents as a sensorineural or mixed hearing loss. On CT scanning, a ring of lucency around the cochlea is characteristic of it ("double ring sign")-- Diagnosis of otosclerosis is usually based on clinical & audiologic findings, & CT is rarely indicated.# Medical treatment of otosclerosis- Sodium fluoride- Indication: Cochlear otosclerosis- It reduces osteosclerotic bone resorption.- It has anti-enzymatic action on proteolytic enzymes, which are cytotoxic to cochlear cells# Surgical treatment- Fenestration operation- Mobilization of stapes- Stapedectomy (Treatment of choice)- Indications:# Otosclerosis with bone conduction level of 0-25 dB speech range and air conduction 45-65 dB.# Air-bone gap should be at least 20 dB.