What is the characteristic type of tympanogram associated with Otosclerosis?

The characteristic type of tympanogram associated with otosclerosis is Type A. A Type A tympanogram indicates normal middle ear function with normal mobility of the tympanic membrane and ossicular chain. In cases of otosclerosis, although there may be a conductive hearing loss due to the fixation of the stapes bone in the oval window, this condition often maintains a relatively normal compliance reading on the tympanogram if the middle ear space is filled with air.

In specific cases of otosclerosis, especially in its early stages, patients may still present with a normal Type A tympanogram because the tympanic membrane and the linked ossicles have not yet undergone significant compromise. This contrasts with conditions like fluid in the middle ear, which would present as Type B, or Eustachian tube dysfunction, which would typically show as Type C. Thus, while otosclerosis leads to hearing loss, it typically does not initially affect the mobility of the tympanic membrane, explaining why Type A is considered the correct association for otosclerosis.