Natasha Nehra

Background: The facial nerve is the seventh cranial nerve and innervates the facial muscles and the lacrimal/ salivary glands. Paralysis of this nerve results in large disability or total loss of facial movement including laxity, corneal exposure, ptosis of the brow, respiratory collapse of the nasal vestibule, inability to smile and oral incompetence; 79% of patients in a study reported difficulties eating and 55% reporting swallowing dysfunction¹. Facial nerve paralysis can result from trauma, Bell’s palsy, parotidectomy, and a tumor on the nerve. It has significant physical, mental, and psychosocial impacts on a person’s life².

Methods: The author independently searched Pubmed and Google Scholar using the following keywords “facial nerve reconstruction”, “facial reanimation”, “cross-facial nerve grafting”, “nerve grafts”.

Results: The first study characterized the differences between an interposition (17 patients) and a masseter nerve graft (15 patients). An interposition nerve graft, typically the sural nerve, is used to bridge the gap between the two damaged facial nerve stumps. With an interposition graft, a strong smile was seen, but all smiles remained asymmetrical. With a masseter graft, the facial symmetry score was 2.3, compared to 1.6 in the interposition graft. There was slight or no synkinesis noted in the masseter nerve group. In the interposition group, severe synkinesis was noted when a strong smile was elicited³. In study two, a hypoglossal facial nerve graft was evaluated in patients with long-term facial paralysis. In 17 patients, when smiling the face was mildly asymmetrical in 59% and was designated as ‘severely disfiguring’ in 38%⁴. In the third study, a cross-facial nerve graft was used with a free flap muscle transfer in 27 patients. This technique required extensive exposure of the facial nerve and masseter transfer on the side that was affected. A spontaneous smile was achieved in 22 out of the 27 patients and the resting symmetry was improved by 3.8mm in relevant cases⁵. The fourth study evaluated temporalis facial muscle transposition in 32 patients. The smile angle on the affected and non-affected side showed statistically significant differences when evoked but not at rest. This study did not discuss eliciting a spontaneous smile.

Conclusion: Each technique has its advantages and disadvantages and comes with a steep learning curve but the cross-facial nerve graft was far superior in producing a natural, spontaneous smile. With future investigations, time for rehabilitation should be investigated and minimized while controlling for the ability to smile.

Works Cited:

1.  Secil Y., Aydogdu I., Ertekin C. Peripheral facial palsy and dysfunction of the oropharynx. J. Neurol. Neurosurg. Psychiatry. 2002;72:391–393. doi: 10.1136/jnnp.72.3.391
2. Renkonen S., Sayed F., Keski-Säntti H., Ylä-Kotola T., Bäck L., Suominen S., Kanerva M., Mäkitie A.A. Reconstruction of facial nerve after radical parotidectomy. Acta Oto-Laryngol. 2015;135:1065–1069. doi: 10.3109/00016489.2015.1050604
3. Wang WJ, Zhu WD, Tremp M, et al. Facial reanimation with interposition nerve graft or masseter nerve transfer: a comparative retrospective study. Neural Regen Res. 2022;17(5):1125-1130. doi:10.4103/1673-5374.324862
4. Kleijwegt MC, Wever C, Hensen EF, Jansen JC, Koot RW, Malessy MJA. Reestablishment of the Smile after Hypoglossal-Facial Nerve Transfer: What Can We Learn?. J Neurol Surg B Skull Base. 2023;85(5):546-552. Published 2023 Aug 11. doi:10.1055/a-2128-5191
5. Morley SE. Combining an end to side nerve to masseter transfer with cross face nerve graft for functional upgrade in partial facial paralysis-an observational cohort study. J Plast Reconstr Aesthet Surg. 2021;74(7):1446-1454. doi:10.1016/j.bjps.2020.11.015
6. Park H, Kim DJ, Chung JH, Yoon ES, Park SH. Quantitative analysis of facial symmetry and animation following intraoral orthodromic temporalis transfer in facial paralysis. Journal of Cranio-Maxillofacial Surgery. 2023;51(5):272-279. doi:https://doi.org/10.1016/j.jcms.2023.05.016