Temporalis Transposition

The principle of the temporalis transposition procedure is to transpose an innervated, vascularized strip of temporalis muscle for immediate restoration of facial symmetry at rest and potentially to restore facial motion. The muscle is innervated by a motor branch of the trigeminal nerve and derives its blood supply primarily from the deep temporal branch of the internal maxillary artery, which enters the muscle on its deep surface. Through a hemicoronal incision, a 2-cm strip of the muscle is elevated, rotated over the zygomatic arch, and sutured to the lateral edge of the orbicularis oris muscle to achieve the desired upward pull and restore symmetry at rest. The distal end of the muscle is split and sutured around the commissure. Overcorrection of the upward pull is essential. The patient then learns to smile by activating the innervated temporalis flap through motions such as biting or clenching teeth. Indications for temporalis muscle transposition include

(1) absence of distal facial nerve fibers, (2) motor endplates not likely to be viable, (3) associated soft tissue defect in the cheek, and (4) alternative to or failed neural anastomosis procedures. The advantages of temporalis muscle transfer are ease of performance, immediate restoration of midfacial symmetry, and potential for restoring movement. Its disadvantages are (1) the restored facial motion is not spontaneous and has to be learned by activating the temporalis muscle,

(2) chronic temporal mandibular joint pain from loss of temporalis function, (3) bulkiness over the zygomatic arch, and (4) temporal depression, which can be minimized by reconstructing the temporal fossa. If the defect is not very deep, a temporoparietal fascial flap (TPFF) may be sufficient to prevent postoperative temporal fossa hollowing. The temporoparietal fascia is a thin fascial layer between the subcutaneous fat and the superficial layer of the temporalis fascia supplied by the superficial temporal artery. The TPFF

is elevated and set aside prior to elevation of the temporalis muscle and can later be rotated into the temporal defect. If additional augmentation is required, an alloplastic implant, such as a Silastic block, Gore-Tex (W.L. Gore & Associates, Flagstaff, AZ), AlloDerm (Life Cell Corp., Woodlands, Tx) or hydroxyapatite cement (Bone-Source, Leibinger, Carroll-ton, TX) can be placed in the temporal fossa and covered with the TPFF.

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