Ocular palsy following Le Fort 1 osteotomy: a case report

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.

The pterygomaxillary junction: An imaging study for surgical information of LeFort I osteotomy

Maxillary osteotomy is a common surgical procedure and often involves separation of the pterygomaxillary junction (PMJ), which is a “blinded” procedure with inherent risks. Knowledge of the PMJ structure is essential. It remains unclear whether patients with different facial types have different PMJ structures, or different surgical outcome. This study evaluated the computed tomographic images of 283 consecutive patients who received orthognathic surgery. Patients were classified into Angle class I, II, III and cleft lip/palate groups. The results showed that the PMJ was 5.1 ± 1.4 mm in thickness, 9.7 ± 1.7 mm in width, and 102.0 ± 4.0 degrees relative to the sagittal plane in the level of posterior nasal spine. There were no statistically significant differences in these measurements among the groups. The class III group demonstrated significantly smaller angle relative to the maxillary occlusal plane. The cleft group showed significantly longer vertical distance between the posterior nasal spine and the lower border of PMJ, shorter distance between the second molar and PMJ, and longer distance between the descending palatine artery and PMJ. With regard to postoperative outcome, the cleft group showed higher incidence of pterygoid plate fracture. The results in this study provide additional surgical anatomic information.

Evaluation of strain values of critical anatomic regions for two different pterygomaxillary approaches in Le Fort I osteotomy: An experimental study

Background

The purpose of this experimental study was to measure stresses both on the pterygoid plates and the skull base following two different pterygomaxillary approaches in Le Fort I osteotomy.

Material and Methods

The prepared skull models were randomly divided into 2 groups of 7. In the first group (A), the pterygomaxillary area was left intact. In the second group (B), pterygomaxillary separation was performed with a fine bur. The stresses were measured by using strain gauges. These strain gauges were attached to 6 different anatomical sites. The skull models were mounted on a servo-hydraulic testing unit. Each model was then subjected to a continuous linear tension until a plastic deformation was seen.

Results

The statistical analyses showed that there were no significant differences (p >.05) between the 2 groups regarding the strain values. Moreover, no statistical differences (p >.05) were found between the two groups in terms of maximum applied forces.

Conclusions

Considering the clinical conditions, the present study shows that when Le Fort I osteotomy performed without pterygomaxillary separation, there is no significant stress on the skull base during the downfracture. Moreover, it is considered that there is no need for an excessive force applied to perform downfracture in Le Fort osteotomies without pterygomaxillary separation.

Key words:Le Fort I, osteotomy, strain, base of skull, pterygoid process.

Three-dimensional finite element model to predict patterns of pterygomaxillary dysjunction during Le Fort I osteotomy

The aim of this study was to determine whether non-linear three-dimensional finite element analysis (3D-FEA) can be applied to simulate pterygomaxillary dysjunction during Le Fort I osteotomy (LFI) not involving a curved osteotome (LFI-non-COSep), and to predict potential changes in the fracture pattern associated with extending the cutting line. Computed tomography (CT) image data (100 snapshots) after LFI were converted to 3D-CT images. 3D-FEA models were built using preoperative CT matrix data and used to simulate pterygomaxillary dysjunction. The pterygomaxillary dysjunction patterns predicted by the 3D-FEA models of pterygomaxillary dysjunction were classified into three categories and compared to the pterygomaxillary dysjunction patterns observed in the postoperative 3D-CT images. Extension of the cutting line was also simulated using the 3D-FEA models to predict the risk and position of pterygoid process fracture. The rate of agreement between the predicted pterygomaxillary dysjunction patterns and those observed in the postoperative 3D-CT images was 87.0% (κ coefficient 0.79). The predicted incidence of pterygoid process fracture was higher for cutting lines that extended to the pterygomaxillary junction than for conventional cutting lines (odds ratio 4.75; P<0.0001). 3D-FEA can be used to predict pterygomaxillary dysjunction patterns during LFI-non-COSep and provides useful information for selecting safer procedures during LFI-non-COSep.

Idiopathic sixth nerve palsy after bimaxillary surgery: a complication or a sequential pathology independent from surgery?

This was a case of a 21-year-old female patient with a very rare and unexpected symptom "diplopia occurring due to the idiopathic sixth nerve palsy" encountered after 2 weeks following bimaxillary surgery performed for the correction of class III malocclusion deformity.

Preoperative and Postoperative CT Scan Assessment of Pterygomaxillary Junction in Patients Undergoing Le Fort I Osteotomy: Comparison of Pterygomaxillary Dysjunction Technique and Trimble Technique-A Pilot Study

PURPOSE

To determine the rate of complications and occurrence of pterygoid plate fractures comparing two techniques of Le Fort I osteotomy i.e., Classic Pterygomaxillary Dysjunction technique and Trimble technique and to know whether the dimensions of pterygomaxillary junction [determined preoperatively by computed tomography (CT) scan] have any influence on pterygomaxillary separation achieved during surgery.

MATERIALS AND METHODS

The study group consisted of eight South Indian patients with maxillary excess. A total of 16 sides were examined by CT. Preoperative CT was analyzed for all the patients. The thickness and width of the pterygomaxillary junction and the distance of the greater palatine canal from the pterygomaxillary junction was noted. Pterygomaxillary dysjunction was achieved by two techniques, the classic pterygomaxillary dysjunction technique (Group I) and Trimble technique (Group II). Patients were selected randomly and equally for both the techniques. Dysjunction was analyzed by postoperative CT.

RESULTS

The average thickness of the pterygomaxillary junction on 16 sides was 4.5 ± 1.2 mm. Untoward pterygoid plate fractures occurred in Group I in 3 sides out of 8. In Trimble technique (Group II), no pterygoid plate fractures were noted. The average width of the pterygomaxillary junction was 7.8 ± 1.5 mm, distance of the greater palatine canal from pterygomaxillary junction was 7.4 ± 1.6 mm and the length of fusion of pterygomaxillary junction was 8.0 ± 1.9 mm.

DISCUSSION

The Le Fort I osteotomy has become a standard procedure for correcting various dentofacial deformities. In an attempt to make Le Fort I osteotomy safer and avoid the problems associated with sectioning with an osteotome between the maxillary tuberosity and the pterygoid plates, Trimble suggested sectioning across the posterior aspect of the maxillary tuberosity itself. In our study, comparison between the classic pterygomaxillary dysjunction technique and the Trimble technique was made by using postoperative CT scan. It was found that unfavorable pterygoid plate fractures occurred only in dysjunction group and not in Trimble technique group. Preoperative CT scan assessment was done for all the patients to determine the dimension of the pterygomaxillary region. Preoperative CT scan proved to be helpful in not only determining the dimensions of the pterygomaxillary region but we also found out that thickness of the pterygomaxillary junction was an important parameter which may influence the separation at the pterygomaxillary region.

CONCLUSION

No untoward fractures of the pterygoid plates were seen in Trimble technique (Group II) which makes it a safer technique than classic dysjunction technique. It was noted that pterygoid plate fractures occurred in patients in whom the thickness of the pterygomaxillary junction was <3.6 mm (preoperatively). Therefore, preoperative evaluation is important, on the basis of which we can decide upon the technique to be selected for safer and acceptable separation of pterygomaxillary region.

Evaluation of Post-operative Complication Rate of Le Fort I Osteotomy: A Retrospective and Prospective Study

Le Fort I osteotomy has become a routine procedure in elective orthognathic surgery. This procedure is often associated with significant but rare post-operative complications. The study was conducted to evaluate the rate of post-operative complications following conventional Le Fort I osteotomy. Twenty-five healthy adult patients who had to undergo Le Fort I osteotomy without segmentalization of maxilla were included in the study based on indications of surgery. All the patients were followed up for a period of 6 months post-operatively to assess the rate of various post-operative complications such as neurosensory deficit, pulpal sensibility, maxillary sinusitis, vascular complications, aseptic necrosis, unfavourable fractures, ophthalmic complications and instability or non-union of maxilla, etc. The results of our study showed a post-operative complications rate of 4 %. Neurosensory deficit and loss of tooth sensibility were the most common findings during patient evaluation at varying follow-up periods while one patient presented with signs and symptoms of maxillary sinusitis post-operatively. Neurosensory as well as sinusitis recovery took place in almost all the patients within 6 months. It was concluded that thorough understanding of pathophysiological aspects of various complications, careful assessment, treatment planning and the use of proper surgical technique as well as instrumentation may help in further reducing the complication rate.

Factors predictive of pterygoid process fractures after pterygomaxillary separation without using an osteotome in Le Fort I osteotomy

OBJECTIVE

This study demonstrated pterygomaxillary disjunction patterns and elucidated factors related to unfavorable pterygomaxillary junction fractures in Le Fort I osteotomy without using an osteotome.

STUDY DESIGN

Clinical and anatomical data obtained from computed tomography images (100 sides) were analyzed for their ability to predict patterns of pterygomaxillary disjunction.

RESULTS

Separation of the pterygomaxillary junction was most frequently performed at the maxillary tuberosity (48.0%). Twenty-eight pterygoid plates were fractured. Male gender, increased age, thickness of the pterygomaxillary junction, and length of the maxillary tuberosity were significant risk factors for pterygoid process fractures. We also identified that a pterygomaxillary junction thickness less than 2.6 mm and a maxillary tuberosity length of more than 11.5 mm indicated a statistically significant risk of pterygoid process fractures.

CONCLUSIONS

Prediction of frangible pterygoid plates by preoperative quantitative evaluation of morphometric values provides useful information for selecting safe procedures.

Evaluation of pterygomaxillary anatomy using computed tomography: are there any structural variations in cleft patients?

PURPOSE

Structural characteristics of the pterygomaxillary region in patients with cleft lip and palate (CLP) have not been fully investigated. This study aimed to evaluate the regional anatomy of the pterygomaxillary junction of patients with CLP using computed tomography.

MATERIALS AND METHODS

The pterygomaxillary structures of patients with unilateral or bilateral CLP were compared with those of a control group using axial computed tomography. The thickness and width of the pterygoid plate, the distance from the greater palatine foramen to the lateral pterygomaxillary junction, the lateral and medial pterygoid plate lengths, and the maxillary posterior transverse width were investigated with axial computed tomography just beneath the level of the inferior nasal concha and approximately 3 to 5 mm above the nasal floor. The difference between the cleft and noncleft sides or the right and left sides of each group and the measurement differences between the groups were statistically compared.

RESULTS

The study group was composed of 14 patients with unilateral CLP and 6 with bilateral CLP, and the control group were 20 age- and gender-matched patients with skeletal Class III without CLP. Patients with unilateral CLP and those with bilateral CLP were statistically equivalent for all radiographic variables. In patients with CLP, the width of the pterygomaxillary region and the greater palatine foramen region were on average 1.5 to 1.8 mm larger than in control patients (P < .05). Lateral pterygoid plate length and maxillary posterior transverse width were similar in the 2 groups. However, the patients with CLP showed a 2.3-mm shorter medial pterygoid length (P < .05).

CONCLUSION

Patients with CLP had larger and thicker pterygomaxillary dimensions, and the results imply that careful attention to pterygomaxillary anatomy is needed in patients with CLP undergoing Le Fort I surgery.

Facial palsy after inferior alveolar nerve block: case report and review of the literature

Bell's palsy is an idiopathic and acute, peripheral nerve palsy resulting in inability to control facial muscles on the affected side because of the involvement of the facial nerve. This study describes a case of Bell's palsy that developed after dental anaesthesia. A 34-year-old pregnant woman at 35 weeks of amenorrhea, with no history of systemic disease, was referred by her dentist for treatment of a mandibular left molar in pulpitis. An inferior alveolar nerve block was made prior to the access cavity preparation. 2h later, the patient felt the onset of a complete paralysis of the left-sided facial muscles. The medical history, the physical examination and the complementary exams led neurologists to the diagnosis of Bell's palsy. The treatment and results of the 1-year follow-up are presented and discussed. Bell's palsy is a rare complication of maxillofacial surgery or dental procedures, the mechanisms of which remain uncertain.

Prospective study of the incidence of serious posterior maxillary haemorrhage during a tuberosity osteotomy in low level Le Fort I operations

The incidence of serious haemorrhage in Le Fort I osteotomy is low and attempts to reduce this further have led to the development of various techniques to minimise vascular injury. This includes the tuberosity osteotomy and was published over two decades ago. This technique has not been widely adopted as shown by a recent UK survey of consultants, which suggested that only 12 (7%) of the 175 surgeons who responded, routinely use tuberosity osteotomy in non-cleft low level Le Fort I procedures. The aim of the study was to examine prospectively the incidence of serious haemorrhage from the posterior maxilla during tuberosity osteotomy. We report 35 consecutive patients who have had no operative or postoperative vascular complications.