NOTE: The assumption is that the procedure is a Type I tympanoplasty.
Parameters:
(1) tympanometric volume in cubic cm
(2) disease of the contralateral ear
Tympanometry measures the volume of air open to the outside. With an intact tympanic membrane it measures the volume of the external ear canal, which ranges from 0.4 to 1.0 cc. With a perforated tympanic membrane it includes the middle ear cavity and the mastoid air cells.
Disease of the contralateral ear was defined as one or more of the following:
(1) ear infection
(2) middle ear effusion
(3) ear discharge
(4) need for ventilation tube
|
Parameter
|
Finding
|
Points
|
|
tympanometric volume
|
>= 3 cc (3.0 to 6.0)
|
1
|
|
|
< 3 cc (0.7 to 2.9)
|
0
|
|
disease in contralateral ear
|
absent
|
1
|
|
|
present
|
0
|
number of predictors of success =
= SUM(points for the 2 parameters)
Interpretation:
• minimum number of predictors: 0
• maximum number of predictors: 2
• The higher the number of predictors the better the chances of successful tympanoplasty.
• For a patient with no predictors, the success rate was 19%.
• If the tympanometric volume was >= 3 cc then the success rate was 89%.
• Timing of the tympanoplasty should take into consideration of these factors, with preoperative interventions intended to normalize any problems.
Limitations:
• There are 4 possible combinations of the predictors. The exact number of patients in each group is hard to determine, Therefore the success rate for patients with a small volume but normal contralateral ear is hard to determine.
