Facial nerve injuries after sagittal split mandibular ramus osteotomies for advancement: a report of 2 cases and review of the literature

Cranial Nerve Injuries in Orthognathic Surgery: A Review of Literature

ABSTRACT

Orthognathic surgery is increasingly utilized to correct facial deformities and dental malocclusions, as well as to enhance facial aesthetics. Significant advancements in surgical planning and execution have made it more widespread and accessible. However, unfavorable outcomes or complications can occur, leading to potentially severe and possibly long-term consequences, such as cranial nerve injuries. This literature review investigates the cranial nerve complications associated with orthognathic surgery. We conducted an extensive search across available databases, analyzing relevant studies published up to September 30, 2023. Two authors independently selected articles for full-text review based on their titles and abstracts. The eligible studies reported cranial nerve injuries in individuals who had undergone orthognathic surgery. Our findings highlight the risk of cranial nerve injuries, their possible mechanism, management, and outcomes. It is imperative for surgeons to remain vigilant and informed and to communicate such information during preoperative patient consultation.

Facial palsy after orthognathic surgery: A systematic review

It was the aim of the systematic review to evaluate the incidence of facial palsy following orthognathic surgery, and to assess the possible mechanisms of injury, subsequent management, and eventual outcomes. The protocol of this systematic review was registered in the International Prospective Register of Systematic Reviews. A thorough search of PubMed, Scopus, Cochrane Library, and CINAHL databases up to April 2022 was conducted. In total, 34 articles were selected for this review, including 54 facial palsies in 53 patients. The incidence of facial palsy was estimated to range from 0.04% to 0.77%. Most of the possible etiologies proposed involved intraoperative nerve compression or postoperative edema. Physical therapy and steroid administration were the most frequently employed management approaches. Surgical exploration for the facial nerve was executed in one patient. Forty-three facial palsies (79.6%) attained complete recovery with conservative management, whereas 11 facial palsies (20.4%) continued to show incomplete recovery during the follow-up period. Earlier facial palsy onset (timing after surgery) was related to a higher risk of continuing palsy (p = 0.018). Within the limitations of this review it seems that facial palsy following orthognathic surgery should be treated conservatively whenever appropriate.

Skeletal posterior crossbite in patient with mandibular asymmetry: an alternative solution

Introduction:

Skeletal posterior crossbite (SPCB) has a multifactorial etiology, as it may be caused by parafunctional habits, atypical position of the tongue, tooth losses and maxillary or mandibular transverse skeletal asymmetries. Skeletal involvement may lead to facial changes and an unfavorable aesthetic appearance. The treatment of SPCB diagnosed in an adult patient should be correctly approached after the identification of its etiologic factor. Surgically-assisted rapid maxillary expansion (SARME), one of the techniques used to correct SPCB in skeletally mature individuals, is an efficient and stable procedure for the correction of transverse discrepancies that may be performed in the office or in a hospital.

Objective:

This study discusses the results of asymmetrical SARME used to correct unilateral SPCB associated with transverse mandibular asymmetry.

Conclusion:

The treatment alternative used in the reported case was quite effective. At the end of the treatment, the patient presented adequate occlusion and facial aesthetics.

Peripheral facial palsy after bilateral sagittal split ramus osteotomy: case report

Bilateral sagittal split ramus osteotomy (BSSRO) is commonly used in orthognathic surgery. Although abnormal sensation in areas that are innervated by the inferior alveolar nerve is a well-known neurological complication of mandibular osteotomy, facial palsy is rare postoperatively. We present a case of peripheral facial palsy that developed the day after BSSRO to correct a mandibular protrusion in a 42-year-old man. Oral prednisolone was begun on the second day postoperatively, and was gradually tapered off over time. One month after operation, he had gradually recovered all movements in his right facial muscle and, after two months, had completely recovered without residual asymmetry. Possible causes of the palsy were compression of the facial nerve as a result of the insertion of a retractor around the posterior border of the ramus, and postoperative oedema. Peripheral facial palsy after BSSRO should be considered a rare, but possible, complication and as such, should be mentioned in consent forms.

Variant anterior digastric muscle transfer for marginal mandibular branch of facial nerve palsy

Summary:

Marginal mandibular branch of facial nerve (MMBFN) palsy is a common consequence of head and neck surgeries. MMBFN palsy results in paralysis of muscles which depress the inferior lip. Current management of MMBFN palsy involves ruination of normal neuromuscular anatomy and physiology to restore symmetry to the mouth. The article outlines the possibility to transfer variant anterior digastric musculature to accomplish reanimation of the mouth without adversely affecting normal nonvariant anatomy. The procedure may have the additional cosmetic benefit of correcting asymmetrical muscular bulk in the submental region.

[Modified Risdon approach for non-traumatic ramus surgery]

INTRODUCTION

The Risdon modified approach, for mandibular surgery, is well adapted to treatment of low subcondylar fractures. According to our experience, this approach with a low rate of complications should also be considered for non-traumatic ramus surgery.

MATERIAL AND METHODS

Twenty Risdon modified approaches were used in 11 patients for non-traumatic indications (seven bilateral osteotomies, four unilateral osteotomies, one biopsy, one bone graft). One patient was operated twice with the same approach.

RESULTS

In all cases, the planned surgery could be performed using this approach. The only complication was a case of temporary paresis of the facial nerve's mandibular branch. The scar was always considered as quite acceptable.

DISCUSSION

As for traumatology, the Risdon modified approach is an improvement for ramus non-traumatic surgery. It has a very low rate of complications, especially for the facial nerve. The intraoral approach avoids scarring, but the resulting exposure is insufficient and requires using a transcutaneous device or endoscopy. In orthognathic surgery, the wide exposure of the lateral aspect of the ramus, the corpus, and the basilar edge, facilitates important mandibular advancement.

Platelet rich plasma may enhance peripheral nerve regeneration after cyanoacrylate reanastomosis: a controlled blind study on rats

The aim of this study was to explore the ability of platelet rich plasma (PRP) to promote peripheral nerve regeneration after cyanoacrylate reanastomosis in rats. A total of 18 rats were used in this study. Bilateral sciatic neurotomies were performed in 15 rats, and then immediately reanastomosed with cyanoacrylate glue. On one side (G1), the anastomosed nerves were treated with prepared autologous PRP gel; on the contralateral side (G2) the nerves received no additional treatment. Sham surgery was undertaken on the remaining 3 rats (6 cases) where bilateral sciatic nerves were surgically approached but not cut (passive control group, (G3). Biopsies were harvested 12 weeks postoperatively and examined under the light microscope using osmic acid stain. The number of nerve fibers in the distal and proximal nerve segments of G1 and G2 as well as in G3 were counted and the results analyzed and compared. Animals in G1 and G2 showed some weakness and ulceration in their right and left feet for a few weeks postoperatively, which gradually improved during the follow-up period. The histomorphometric assessment showed a higher axon count in the distal segment of G1 (291.7 axons) compared with that of G2 (280.5 axons) (P=0.001). Similar results were noticed when the proximal segments of both groups were compared (P=0.040). These results were reflected in the values of the neurotization indices of G1 (91.9%) and G2 (89.5%) (P=0.008). The number of nerve fibers in G1 and G2 remained lower than in G3 (P=0.0001). The authors conclude that PRP may enhance the number of regenerating nerve fibers after cyanoacrylate neruoanastomosis.