xRead - May 2023

Refinements in smile reanimation

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noticeable site of this hollowing occurs in the 5 cm of non hair-bearing skin lateral to the lateral orbital rim. This visual stigmata further exacerbates facial asymmetry and hence a number of techniques have between attempted to minimise the loss of volume 15 including dermis fat grafts, silastic blocks, lateral arm flaps, and temporoparietal fascial flap. The LTM in itself avoids temporal hollowing by use of two manoeuvres. The first step will be familiar to surgeons who are accustomed to craniofacial approaches to the face and involves carefully preserving the superficial temporal fat pad on the coronal flap and accurately dissecting just above the deep temporal fascia. Gaining access to this plane is ach ieved using the Tessier technique where one dissects down the lateral orbital rim in the subperiosteal plane and the flap is then levered off when the tip of the periosteal elevator reaches the body of the zygoma (Figure 3). As well as causing temporal hollowing, 16 fat left on the deep temporal fascia will cause difficulty in mobilising the muscle from under the zygomatic arch and a problematic subsequent osteosyn thesis of the zygomatic osteotomy. However in a small number of suitable cases it may be possible to osteotomise the coronoid process through the nasolabial incision alone, which avoids the requirement for a zygomatic osteotomy. 22 A further important step to avoid temporal hollowing is to ensure that after the muscle has been rotated anteriorly, the remaining strip of deep temporal fascia on the lateral orbital rim during flap elevation must be fixed securely to the muscle. Supplementary video associated with this article can be found, in the online version, at doi:10.1016/j.bjps.2012.02. 006. Insertion of the temporalis to the lip Perhaps the most important part of the LTM technique is the careful insertion of the temporalis tendon to the lip. The importance of pre-operative smile analysis cannot be over-stressed, and photographs of the patient with the key points marked should be referred to intra-operatively. The key-points are located in the plane of the mimic muscles by

In the majority of patients, action of the lip elevators produces subtle pits and humps in the skin corresponding to the muscles insertion points (Figure 2). Which of these point(s) is dominant will depend on the type of smile that the patients exhibit. 10 In Rubin’s classification, most people (67%) exhibit a ‘Mona Lisa smile’ where the dominant vector originates from the corner of the mouth. In the canine smile (31%), the lip elevators dominate and contribute to a pronounced medial nasolabial fold. 11 This is a difficult smile to reanimate as the creation as an over strong vector on the medial upper lip may result in oral incompetence. The least common smile defined by Rubin is the ‘Full denture’ or “Hollywood smile” (2%) which is characterised by a strong action of both the lip elevators, and the lip depressors. Identifying this smile pre operatively is important because standard reanimation techniques will always create an asymmetric smile due to the lack of lower lip depressor action on the paralysed side. The senior author routinely uses botulinum toxin to coun teract the action of the lower lip depressors at the time of upper lip reanimation in these patients in order to symmetrize. Alternatives to botulinum toxin injections include myectomy of the depressor labii inferioris, 12 or selective marginal mandibular neurectomy. 13,14 Post operative botulinum toxin injection into the zygomaticus muscles, the levator labii superioris, lower lip depressors or platysma, is also used to manage synkinesis, contralateral hyperactivity of facial muscles or improve smile symmetry.

Surgical refinements and points of technique

Avoiding temporal hollowing One of the major disadvantages of Gillies technique 8 and its modifications 4 is the inevitable temporal hollowing that results from harvesting the temporalis muscle. The most

Figure 3 Intra-operative photo showing the subperiosteal plane of dissection passing the right lateral orbital rim (LOR) down towards the zygoma (Zyg). The temporal fat pad is carefully dissected off the deep temporal fascia (DTF).

Marking out key-points for fixation.

Figure 2