This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: ENT
[{'content': 'Post head injury, the patient had conductive deafness and on examination, tympanic membrane was normal and mobile. Likely diagnosis is: \nSelect and explain. \nA. Distoion of ossicular chain, B. Hemotympanum, C. EAC sclerosis, D. Otosclerosis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Fracture temporal bone (more commonly longitudinal) extending to external canal: tympanic membrane is frequently torn and inner ear is spared.Blood or CSF in external and middle ear.Damage to ossicle (most frequent being incudo-stapedial joint) resulting in more severe and permanent conductive deafness.Aseptic necrosis of long process of incus can lead to late conductive deafness. Tympanic membrane is normal and mobile: In hemotympanum - tympanic membrane will appear red/blue (due to presence of blood pigments) so it is ruled out. ... Logan Tumer1Oth/ed p441 Otosclerosis and EAC sclerosis do not occur in case of head injury and hence they are ruled out', 'role': 'assistant'}]