REANIMATION OPTIONS IN PATIENTS WITH HEMIFACIAL MICROSOMIA AND MARGINAL MANDIBULAR NERVE PALSY

Dynamic Reconstruction of Facial Paralysis in Craniofacial Macrosomia

BACKGROUND

Craniofacial microsomia is associated with maxillomandibular hypoplasia, microtia, soft-tissue deficiency, and variable severity of cranial nerve dysfunction, most often of the facial nerve. This study evaluated the incidence of patients with craniofacial microsomia and facial paralysis and their outcomes after free functioning muscle transfer for dynamic smile reconstruction.

METHODS

A single-center, retrospective, cross-sectional study was performed from 1985 to 2018 to identify pediatric patients with craniofacial microsomia and severe facial nerve dysfunction who underwent dynamic smile reconstruction with free functioning muscle transfer. Preoperative and postoperative facial symmetry and oral commissure excursion during maximal smile were measured using photogrammetric facial analysis software.

RESULTS

This study included 186 patients with craniofacial microsomia; 41 patients (21 male patients, 20 female patients) had documented facial nerve dysfunction (22 percent), affecting all branches (51 percent) or the mandibular branch only (24 percent). Patients with severe facial paralysis (n = 8) underwent midfacial (i.e., smile) reconstruction with a free functioning muscle transfer neurotized either with a cross-face nerve graft (n = 7) or with the ipsilateral motor nerve to masseter (n =1). All patients achieved volitional muscle contraction with improvement in symmetry and oral commissure excursion (median, 8 mm; interquartile range, 3 to 10 mm). The timing of orthognathic surgery and facial paralysis reconstruction was an important consideration in optimizing patient outcomes.

CONCLUSIONS

The authors' institution's incidence of facial nerve dysfunction in children with craniofacial microsomia is 22 percent. Free functioning muscle transfer is a reliable option for smile reconstruction in children with craniofacial microsomia. To optimize outcomes, a novel treatment algorithm is proposed for craniofacial microsomia patients likely to require both orthognathic surgery and facial paralysis reconstruction.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Revisiting the Topographic Anatomy of the Marginal Mandibular Branch of Facial Nerve Relating to the Surgical Approach

BACKGROUND

The marginal mandibular branch (Mbr) of the facial nerve is vulnerable to damage during rhytidoplasty, surgical reduction of the mandibular angle, parotidectomy, and excision of the submandibular gland.

OBJECTIVES

The authors sought to map the Mbr and determine the relationship between the number of Mbr offshoots and the course of the Mbr.

METHODS

The Mbr was examined in 29 hemifaces from 12 embalmed and 4 fresh cadavers (10 males, 6 females; mean age, 73.7 years).

RESULTS

The Mbr was located ≤5 mm from the gonion (Go) in 24 of 29 hemifaces (82.8%) and ≤10 mm from the intersection of the facial artery and mandible (ie, FM) in 26 hemifaces (89.7%). In 16 hemifaces (55.2%), offshoots arose from the Mbr inferior to the mandible. The Mbr ran below the Go in 14 hemifaces (48.3%) and ran below FM in 13 hemifaces (44.8%). Except for minute offshoots deep to the platysma, the Mbr was not found to pass >2 cm below the mandible. The mean (± standard deviation) quantity of Mbr offshoots was 1.5 (± 0.6). A greater number of offshoots was associated with a higher likelihood of an inferiorly located nerve. The Mbr proceeded under the lower border of the mandible in 13 hemifaces (44.8%) and reached the mandible at a mean distance of 33.1±5.2 mm anterior to the Go.

CONCLUSIONS

To avoid damaging the Mbr, surgical maneuvers should be positioned 4.5 cm anterior to the Go and 2 cm below the mandible.

Characterization of Facial Paresis in Hemifacial Microsomia

Objective

To provide an overview of the incidence, characteristics, and proposed etiologic mechanisms of facial paresis in patients with manifestations of hemifacial microsomia.

Data Sources

PubMed database for English-language studies with no date restrictions.

Review Methods

A comprehensive literature review was performed identifying all studies that discussed incidence, characterization, or etiologic mechanisms for facial paresis in hemifacial microsomia/oculo-auriculo-vertebral spectrum.

Conclusions

This review supports that the prevalence of facial weakness in the spectrum of hemifacial microsomia/oculo-auriculo-vertebral spectrum ranges from 10% to 45%. Most of these patients have involvement of all facial nerve branches or lower branches only. The most commonly involved single nerve branch has yet to be described. The 2 most common associated anomalies involve the mandible and auricle. Dysmorphogeneisis of the temporal bone and its effects on the facial nerve are most likely implicated in the cause of facial weakness.

Implications for Practice

There is a wide variety of facial nerve presentations seen within oculo-auriculo-vertebral spectrum for which the exact etiologic mechanism is unclear. Through a better understanding of the presentation and etiology surrounding facial paresis in hemifacial microsomia, improved treatment options may be offered in the management of the facial weakness.