Objectives:
1- Describe the anatomical bases related to the concept of the functional
endoscopic tympanic surgery (FETS) based on the fact that restoring adequate
tympanic cavity ventilation is one of the main key factors to
achieve
this concept and restore normal middle ear functions.
2- Review and explain the possible theory and concept of the FETS in relation
to these bases.
Methods: Fifty-five temporal bones were dissected, and the ventilation
pathways were studied utilizing otoendoscopes of different angles and an
operating microscope. In addition, the anatomy and relations of these pathways
were studied in 200 temporal bones computed tomography scans
(CT).
Results:
The
ventilation pathways of the tympanic cavity (with all of its subdivisions)
and the mastoid air cells were variable and unique for each temporal
bone. Basically, the ventilation patterns could be classified either directly
from the eustachian tube or indirectly through communicating with
other
spaces via mucosal, ligamental and/or bony apertures or isthmi. Mesotympanum,
protympanum, hypotympanum and anterior epitympanum type
C
were the only spaces directly ventilated, while retrotympanum with all of
its
recesses, anterior epitympanum types A and B, Prussak's space, von
Troeltsch
pouches, compartments of posterior epitympanum (medial and
lateral
superior and medial incudal spaces), antrum and mastoid air cells
were
indirectly ventilated. It was possible to approach most of the pathways
endoscopically
via transcanal or combined transcanal and transmastoid approaches.
Conclusions: Theoretically, ventilation pathways could be endoscopically
approached and therefore restored in certain cases. CT scans are a possible
tool to study them.