Classification of pars flaccida retraction pocket
Pars flaccida retractions have a vital role to play in the pathophysiology of cholesteatoma. Tos et al classified pars flaccida retraction in to four stages.
Stage I: Pars flaccida is dimpled and is more retracted than normal. It is not adherent to the malleus.
Figure showing Toss stage I retraction
Stage II: In this stage the retraction pocket is adherent to the handle of malleus. The full extent of the retraction pocket can be clearly seen.
Figure showing Toss stage II retraction pocket
Stage III: In this stage part of the retraction pocket may be hidden. There may also be associated erosion of the outer attic wall (scutum).
Figure showing Toss stage III retraction pocket
Stage IV: In this stage there is definite erosion of the outer attic wall. The extent of the retraction pocket cannot be clearly seen as most of it are hidden from the view.
Figure showing Toss stage IV retraction pocket
This classification described by Toss is fairly simple to apply, the only difficulty being the difficulty in making a distinction between stages 3 and 4. Hence for practical purposes these two stages are grouped together.