The Subzygomatic Triangle: Rapid, Minimally Invasive Identification of the Masseteric Nerve for Facial Reanimation
ABSTRACT BACKGROUND:: The masseteric nerve is a valuable donor nerve in the management of facial paralysis, however its location is less familiar to surgeons because this motor nerve is not commonly exposed in other head and neck procedures. Current techniques for masseteric nerve identification rely on physical measurements from surface or bony landmarks that may be unpredictable across patient age, ethnicity and size. We sought to identify a rapid and minimally invasive technique based on surgical anatomy independent of intra-operative physical measurements. METHODS:: A two phase fresh frozen cadaver study was performed followed by a clinical application that included 11 consecutive patients undergoing facial reanimation procedures between May 2012 and October 2012. RESULTS:: Ten cadavers were dissected and 11 clinical applications are reported. In all dissections the masseteric nerve was identified through the newly described "Subzygomatic Triangle". This triangle is formed by the zygomatic arch superiorly, the temporomandibular joint posteriorly, and the frontal branch of the facial nerve inferiorly and anteriorly. This finding was consistent across patient ages (8-49 years) and ethnicities. Through using the short scar, minimal dissection approach described in the study, average time to nerve identification was 10.2 minutes during the clinical application. CONCLUSION:: The subzygomatic triangle is a consistent anatomic landmark for rapid, reliable and minimally invasive identification of the masseteric nerve. The use of the subzygomatic triangle obviates the need for extensive dissection and surgeon reliance upon soft tissue measurements that may vary between patients of different size, gender or ethnicity. LEVEL OF EVIDENCE:: IV.
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ABSTRACT: The management of facial paralysis continues to evolve. Understanding the facial nerve anatomy and the different methods of evaluating the degree of facial nerve injury are crucial for successful management. When the facial nerve is transected, direct coaptation leads to the best outcome, followed by interpositional nerve grafting. In cases where motor end plates are still intact but a primary repair or graft is not feasible, a nerve transfer should be employed. When complete muscle atrophy has occurred, regional muscle transfer or free flap reconstruction is an option. When dynamic reanimation cannot be undertaken, static procedures offer some benefit. Adjunctive tools such as botulinum toxin injection and biofeedback can be helpful. Several new treatment modalities lie on the horizon which hold potential to alter the current treatment algorithm.Craniomaxillofacial Trauma and Reconstruction 03/2015; 8(1):1-13. DOI:10.1055/s-0034-1372522
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ABSTRACT: Introduction Botulinum toxin injections are previously reported to be a noninvasive alternative method for treating masseteric hypertrophy. However, there is debate in finding an ideal place for injection. The aim of this study is to document the anatomical landmarks for defining the motor nerve entry points (MNEPs) of the masseteric nerve in the masseter for effective botulinum toxin injections. Materials and methods Twelve sides from 6 adult fixed cadavers were used for this study. The MNEPs of the masseteric nerve were defined according to standard landmark lines including the orbitomeatal line (OML) and the line (VL), which intersects the mid-distance of the OML to the tip of the angle of mandible. Results All MNEPs were located 4.4 cm inferior to the OML. And the average anterior distance of the MNEPs to the VL was 1.4 cm and the average posterior distance was 0.6 cm. Conclusion: The ideal site of botox injection into the masseter is a rectangular area; 5 cm inferior the OML, 1 cm anterior and posterior to the VL and just above the periosteum. Based on the data of our study injections to the parotid gland and branches of the facial nerve such as the marginal mandibular and buccal can be avoided. The masseteric nerve can easily be found approximately 1.0-1.5 cm inferior to the zygomatic arch, 1 cm medial to the temporomandibular joint capsule and 1 cm superior to mandibular notch which makes its use for facial reanimations more efficient.Journal of Plastic Reconstructive & Aesthetic Surgery 12/2014; DOI:10.1016/j.bjps.2014.07.043 · 1.47 Impact Factor
Article: Reanimating the paralyzed face[Show abstract] [Hide abstract]
ABSTRACT: Facial animation is an essential part of human communication and one of the main means of expressing emotions, indexing our physiologic state and providing nonverbal cues. The loss of this important human quality due to facial paralysis can be devastating and is often associated with depression, social isolation and poor quality of life. Interruption of the neuromuscular pathway from the facial motor cortex to the facial muscles is the common causative factor in facial paralysis resulting from various etiologies. Restoring tone, symmetry and movement to the paralyzed face requires timely nerve grafting intervention in cases of reversible paralysis and the transfer of functional muscle units in irreversible paralysis. We review recent advances in these techniques.11/2013; 5:49. DOI:10.12703/P5-49