Tympanogram.

Types of curves in tympanogram:

Type A – Normal pressure and normal compliance in normal ear.

Type A_s – Reduced compliance (‘s’ means stiffness leading to reduced compliance) and normal pressure.

• Seen in
  • Otosclerosis or other ossicular fixation
  • Tympanosclerosis

Type A_d – Increased compliance (‘d’ means discontinuity leading to increased mobility) and normal pressure.

• Seen in
  • Ossicular discontinuity
  • Thin and lax TM

 

Type B – Flat or dome shaped graph i.e. reduced compliance.

Seen in case of:Serous otitis media.

Thick tympanic membrane.

Type C – Normal compliance but negative pressure due to eustachian tube obstruction.

• Seen in case of:
  • Retracted tympanic membrane,
  • Early stages before collection of fluid in middle ear.