Tos & Poulsen Classification of Pars Flaccida Retraction

The Tos and Poulsen Classification (1980) is used to classify retraction of the pars flaccida¹
- The pars flaccida is also known as Shrapnell’s membrane.
The classification system is divided into 5 types:
- Type 0: Normal pars flaccida.
- Type I: Retraction towards the neck of the malleus, with a visible air space behind the pocket.
- Type II: Pars flaccida is retracted and adherent to the neck of the malleus with no visible air space.
- Type III: Retraction extends beyond the bony annulus, with or without slight bone resorption of the annulus.
- Type IV: Definite bony erosion of the annulus.
The corresponding classification system for retraction of the pars tensa is the Sadé Classification.

Tos and Poulsen classification of pars flaccida retraction

Tos, M., and G. Poulsen. “Attic retractions following secretory otitis.” Acta Oto-Laryngologica 89.3-6 (1980): 479-486. ↩

Last updated October 13, 2022