This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Otosclerosis, Subject name: ENT
[{'content': 'True about tympanic membrane: (PGI Dec 2007) \nSelect and explain. \nA. Tympanosclerosis with increased compliance, B. Ossicular disruption with intact tympanic membrane and increased compliance, C. Fluid in middle ear cavity increases compliance, D. Otosclerosis reduces compliance', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. D (Otosclerosis reduces compliance) Tympanometry Tympanometry is an objective test1, widely used in clinical practice & is particularly useful in children. It is based on the principle that when a sound strikes tympanic membrane, some of the sound energy is absorbed while the rest is reflected. A stiffer tympanic membrane reflects more sound energy than a complaint one "by changing the pressures in a sealed external auditory canal & then measuring the reflected sound energy, it is possible to find the compliance or stiffness of the tympano-ossicular system & thus find the healthy or diseased status of the middle ear. By chatting the compliance of tympano -ossicular system against various pressure changes, different types of graphs called tympanogram are: Type - A : Normal Tympanogram \' Type - As: Compliance is lower at or near ambient air pressure. Seen in fixation of ossicles e.g. otosclerosis or malleus fixation. Types AD- High compliance at or near ambient pressure. Seen in the ossicular discontinuity or thin & lax tympanic membraneQ. Type - B :A flat or dome-shaped graph. No Change in compliance with pressure changes. Seen in middle ear fluid or thick tympanic membrane Type - C: Maximum compliance occurs with negative pressure in excess of 100 mm of H20. Seen in retracted tympanic membrane & may show fluid in middle ear(r) Fig.: Types of tympanogram', 'role': 'assistant'}]