MIDDLE EAR RISK INDEX (MERI)
Introduction:
• The term Middle ear risk index is used to predict the success rate of middle ear reconstruction procedures.
• For accurate prediction of the surgical results of middle ear ossiculoplasty the status of middle ear and its ossicles must be ascertained.
• Austine Kartush classification has been used as a method to define the pre reconstruction ossicular status.
Austine Kartush classification:
• This classification uses middle ear osscicular status. Four different groups have been identified:
Group A - Malleus and stapes present (commonly seen status) because of precarious vascularity of incus
Group B - Malleus present and stapes absent
Group C - Malleus absent and stapes present
Group D - Malleus and stapes suprastructure absent
Kartush added three more classes as a modification of this scheme in include ossicular fixity even when all three ossicles are present.
O - Intact ossicular chain
E - Ossicular head fixation
F - Stapes fixation
Middle ear risk index includes:
-
Austin Kartush classification of ossicular defects
-
Ear drum perforation
-
Cholesteatoma
-
Belluci classification
• Weightage is given to these 4 parameters to arrive at the middle ear risk index.
• Perforation if present adds a value of 1 to the risk index
• Cholesteatoma if present adds a value of 2 to the risk index
Austin Kartush classification
-
M+I+S += 0
-
M+S+=1
-
M-S+ = 3
-
M-S- = 4
-
Ossicular head fixation = 2
-
Stapes fixation = 3
• Presence of effusion / granulation in the middle ear adds 2 to the risk index
• History of previous surgery adds 2 to the risk factor
• History of smoking adds another 2 to the risk factor
Belluci classification uses otorrohea as an index.
• Dry Ear - 0
• Occasionally wet - 1
• Persistently wet - 2
• Persistently wet with cleft palate - 3
Totalling all these factors adds to the middle ear risk index.