Midfacial Degloving Approach
This approach which was popularised by Casson et al and Conley is best suited for inferiorly located tumors with minimal ethmoidal involvement. This is more suited for bilateral lesions. This procedure is not suited for extensive tumors which extent higher into the anterior labyrinth with involvement of frontal sinus area.
This surgery is ideally performed under general anesthesia. Bilateral temporary tarsorraphy is performed. The area of surgery is liberally infiltrated with 1% xylocaine mixed with 1 in 200,000 units adrenaline. Infiltration minimizes troublesome bleeding during surgery. The areas to be infiltrated include:
Subperichondrial plane of nasal septum
Membranous portion of nasal septum
Inferior and middle turbinates on both sides
Floor of the nose on both sides
Nasal vestibule on both sides
Bilateral intercartilagenous infiltration extending around the dorsum of the nose, and the anterior wall of maxilla on both sides, up to the glabella of frontal bone.
Transcutaneous injection into the orbit along its medial wall
Sublabial infiltration from the third molar across the midline to the opposite third molar
Trans oral greater palatine injection is also given
The procedure is started with complete transfixion incision, which is connected to bilateral intercartilagenous incisions. Elevation of soft tissue from the nasal dorsum is performed through the intercartilagenous space. The soft tissue elevation over dorsum of nose is continued over the anterior wall of maxilla on both sides. Elevation of soft tissue should also continue over the glabella and frontal bone. Supero laterally the elevation should extend up to the medial canthal region. The intercartilagenous incision is extended laterally and caudally across the floor of the vestibule to be connected with the transfixation incision. This results in a full circumvestibular incision on both sides.
After the transnasal incisions are completed the sublabial incision is performed. It extends from the first molar on oneside across the midline up to the first molar on the opposite side. This incision can be extended up to the third molar if more exposure is needed. The incision is carried down the submucosa, and muscles over anterior wall of maxilla. At the pyriform aperture region this incision is connected to intranasal incisions. Periosteal elevators are used to elevate the soft tissue over the anterior walls of both maxilla up to the level of the orbital rim taking care to protect the infraorbital vessels and nerve. The entire midfacial skin is stripped from the dorsum of the nose and anterior wall of maxilla. This flap includes the lower lateral cartilages, columella with its medial crura. The elevation is continued till the level of glabella superiorly and medial canthus laterally. The bony nasal pyramid and the attached upper lateral cartilages are exposed completely. Two rubber drains (Penrose type) are passed through the nose and upper lip and are used to retract the midfacial flap along with the upper lip. Once in every 15 minutes one of the drain should be released to allow blood supply to the middle portion of the upper lip.
Midfacial degloving approach exposure
Figure showing the nasal incisions made in midfacial degloving approach
The anterior wall of the maxilla is drilled out. Infraorbital neurovascular bundle should be identified and preserved. Bone removal continues superomedially towards the ethmoidal complex. Nasolacrimal sac and duct need to be managed before bony cuts of maxillectomy are performed. Nasolacrimal duct can be transected at the orbital floor level.
The whole anterior wall of maxillary sinus is drilled out including the lateral portion of nasal bone including the edge of the pyriform aperture.
Figure showing the extent of resection
Bone cuts for medial maxillectomy:
Cut along the nasal bone from the pyriform aperture to the glabella a few millimeters anterior to the nasomaxillary groove.
A horizontal cut is made just below the glabella directed posteriroly towards the frontoethmoid suture line.
Antero posterior cut along the fronto ethmoidal suture line.
Oblique cut of the orbital floor from the orbital rim medial to the infraorbital foramen extending postero medially to join the fronto ethmoid cut in the posterior ethmoid region. All these bone cuts should include the attached soft tissues.
The posterior attachment to the ascending process of palatine bone is severed using a heavy scissors.
Complications of midfacial degloving:
Anesthesia over infraorbital nerve area
Nasal valve stenosis