8.3\ Auricular Reconstruction

8.3.1\ Discussion

Ear reconstruction is performed to reproduce the normal appearance of the auricle for conditions such as microtia. Autogenous rib cartilage reconstruction has been one of the more traditional methods. The cartilage grafts often appear calcified (Fig. 8.3). High-density porous polyethylene (Medpor) is a more recent option. Medpor is a

Fig. 8.4  Auricular reconstruction with porous polyethylene. Coronal (a) and sagittal (b) CT images show a low-­attenuation left auricular implant that has near-anatomic configuration

stable alloplastic implant material that can integrate with host tissues and is relatively resistant to infection. For auricular reconstruction, the prosthesis is enveloped in a temporoparietal fascial flap with full-thickness skin graft coverage in order to provide good cosmetic results and minimize the risk of implant extrusion. On CT, Medpor ear prostheses demonstrate attenuation values between fat and soft tissue and are shaped to resemble the natural morphology of the auricle (Fig. 8.4).

a

b

8.4\ Canaloplasty

and Meatoplasty

8.4.1\ Discussion

Canaloplasty and meatoplasty consist of surgically widening the bony external auditory canal and soft tissue/cartilaginous meatus, respectively. This can be performed for treating congenital or acquired canal stenosis and other lesions such as exostoses. Canaloplasty is also often performed as part of a transcanal approach in order to augment­ surgical exposure during middle ear surgery. Meatoplasty is often performed in conjunction with canal wall down mastoidectomy to provide postoperative access to the resultant mastoid cavity for evacuation of debris in the office. The resulting appearance on CT is an external auditory canal with a relatively capacious lumen (Fig. 8.5). In particular, thinning, irregularity, and/ or flattening of the bone, soft tissue thickening, and bony wall defects are common findings on

postoperative imaging and should not be mistaken for pathology. Complications of canaloplasty include canal restenosis, temporomandibular joint violation, osteonecrosis, and facial nerve palsy— especially if the distal aspect of the mastoid portion of the facial nerve courses lateral to the tympanic annulus thereby being at risk of drill trauma in the posterior-inferior aspect of the external auditory canal. If persistent pain, trismus, or delayed healing is encountered after canaloplasty, radiologic assessment of the integrity of the anterior canal wall is made to determine if the temporomandibular joint has been violated and assessment of whether this has resulted in a prolapse of joint capsule into the canal lumen. Chronic otitis externa and failed epithelialization after canaloplasty may suggest the possibility of iatrogenic osteonecrosis from excessive burning of the bone by a drill bur that was applied with insufficient irrigation, which will appear as a lytic defect on CT.