Endoscopic Approach to the Tympanic Cavity: Tympanomeatal Flap and Canalplasty

Canalplasty represents an otologic procedure that allows to enlarge the bony external auditory canal (EAC). This approach can be performed as curative treatment (for exostoses or EAC pathologies) and as a preliminary surgical step during tympanoplasty or approaches to inner ear and lateral skull base. The remodeling of the EAC is thought to be very useful to visualize some difficult areas such as the anterior annulus and the retrotympanum, even though the introduction of the endoscopic transcanal approach has progressively changed this point of view because it provides superior visibility of all middle ear compartments. Moreover, it creates space in order to obtain easy maneuvering of surgical instruments in the middle ear cavity. This represents a very important step in transcanal transpromontorial approaches to the internal auditory canal. Similarly, it is usually needed in surgical training on ovine model due to its relatively small size of the EAC. The endoscopic atticotomy and removal of the posterior wall of the EAC in human specimens are easier than in the ovine model due to the wider size of the canal. A regular drill, a curette, or powered devices (like Piezosurgery; Mectron, Carasco, Genova) can be chosen in order to dissect the bone. Regarding the gestures during ovine training in canalplasty, there is a challenging phase of this approach, related to the necessity to elevate the tympanomeatal flap and protect it during the drilling procedure. This step is very important because it is relatively similar to the removal of exostoses/osteomas in human live surgery. This procedure is not so easy to perform under endoscopic view. All these maneuvers represent an important opportunity to improve the capacity to drill under endoscopic view in a narrow space and to gain more experience in the management of the EAC bone. These skills can be also applied during external auditory canal procedures for EAC cholesteatoma or external ear tumors.