xRead - May 2023

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C. Nduka et al.

bone whilst gently pushing away any muscle fibres with a large periosteal elevator should allow delivery of the coronoid through the nasolabial fold incision. The tendon must be completely freed and tethered only by the tem poralis neurovascular supply. Having verified that the tendon had not twisted during its passage, the coronoid can be excised taking care to preserve as much tendon as possible. Once splayed out the temporalis tendon should reach from the alar base to the modiolus. Unlike temporalis techniques that employ an interposition of fascia lata or periosteum, 7,17 the fact that the tendon is vascularised means that it will not stretch postoperatively. The smile therefore must not be over-corrected. The longest (anterior) part of the temporalis tendon elevates the alar base and corrects the nasal scoliosis, whilst the shortest part creates oral symmetry at rest. The three key-point sutures are passed through the temporalis tendon and supported by further sutures as required. Correct vectors for the smile are verified by traction on the muscle origin (Figure 4a). This manoeuvre also allows fine-tuning of the line of pull of the muscle and correct positioning necessary for the re attachment of the muscle to the temporal crest. One can also verify correct tendon positioning by electrically stimu lating the temporalis muscle belly producing a dynamic smile. This may be performed both directly and indirectly by percutaneous electrode or transcutaneous electrical stimu lation respectively. 20 Adjunctive procedures At the time of the original description of the technique, contralateral myectomies were routinely performed as balancing procedures. However, the risk of inflicting sensory loss on the normal side, as well as loss of function on the paralysed side has discouraged this approach, except in the frontal region. Botulinum toxin injection reliably allows balancing of the smile, as well as correcting the effects of over-active lower lip depressors. An active rehabilitation program that incorporates biofeedback is critical to the success of this technique as outlined previ ously. 6 Indeed, patients should be routinely seen by the speech therapist prior to surgery to optimise outcome. If good rehabilitation services are not available or utilised, the benefits of this technique may not be attained, however adherence to a rehabilitation programme enables patients to develop a spontaneous, natural smile in a rela tively short space of time. Problematic upper lid retraction is managed by levator lengthening using a strip of deep temporal fascia, and lower lid tightening can be achieved by a lateral asymmetric tarsorrhaphy. 21 More recently, a cross facial nerve graft from the unaffected side to one of the three branches of the deep temporal nerves has been performed in younger patients. 18 It is postulated that this technique acts as a trigger to further synchronise the spontaneous smile. Early results with this technique are encouraging.

subcutaneous undermining medial to the nasolabial fold. It is important that the three key-point sutures are first tested to ensure that postero-lateral traction reproduces the smile. Sutures that are placed too superficially at the key-point result in lip eversion, whereas placing the sutures too deeply into the orbicularis results in puckering of the lip (Figure 4b). The lengthened temporalis tendon with the attached coronoid process is retrieved via the nasolabial fold incision. This incision is first undermined subcutaneously for 2 cm before the dissection is deepened through the SMAS into Bichat’s fat pad. If this step is omitted, an unappealing bulge in the cheek will appear when the patient smiles. When the dissection is deepened, this should be performed bluntly to avoid damaging any residual functional facial nerve remnants. The coronoid process with the attached tendon is sometimes difficult to retrieve due to attachments to the masseter and pterygoid muscles. Constant traction on the

Discussion

Figure 4 (a) Appropriate vector traction from key-point sutures resulting in a natural smile. (b) The result from trac tion on an incorrect vector resulting in vermilion eversion and puckering of the lip mucosal.

Since its inception in 1994 the LTM has proved to be an effective and reliable technique for smile reanimation. Importantly, it is a single stage technique, is easily