Nerve Injuries Associated with Facial Trauma

Injury to Anatomic Structures Due to Fixation Device in Management of Mandibular Fracture

INTRODUCTION

ORIF is the gold standard for the management of mandibular fractures. The chances of postoperative complications are due to infection, damage of the inferior alveolar nerve canal, or tooth root during the fixation of the fracture fragments. Fixation hardware placed in the vicinity of the vital structures may encroach on the anatomic structures, leading to postoperative complications.

AIM

The aim of this study is to evaluate the injury to the anatomic structures in the proximity of the fracture line due to the fixation device.

MATERIAL AND METHODS

This retrospective study was conducted in a tertiary care teaching hospital from July 2021 to June 2023. The cases of maxillofacial trauma reported and referred from peripheral centers were considered duly, applying the inclusion and exclusion criteria. Patients having mandibular fractures from one mandibular foramen to another with or without associated other facial fractures were treated by ORIF under general anesthesia. The patient was followed up at 1 week, 1 month, 3 months, and 6 months. The cases of postoperative complications were further investigated by CBCT.

RESULT

There were 67 patients (56 males and 11 females) with 86 fracture lines in the age group of 18-55 years with an average age of 35.2 years. Postoperatively 7 patients presented with unilateral paresthesia of the lower lip and chin region. CBCT revealed that the mean distance of the screw from the inferior alveolar nerve canal was 3.02 mm. None of these cases had injury to the nerve canal or roots of teeth. All the patients recovered from paresthesia within 6 months.

DISCUSSION

Complications like injury to the inferior alveolar nerve (IAN) with sensory disturbances to the lower lip and chin, as well as tooth/tooth root fractures, may occur due to mandibular fracture, surgical manipulation, and fixation devices. The anatomic structures in the vicinity of the fracture line can be damaged during the fixation of the fracture fragments by the bone plates and screws. In the present study, it was found that 7 out of 67 patients presented with unilateral paresthesia of the lower lip and chin. CBCT analysis showed a considerable distance of 3.02 mm from the inferior alveolar nerve canal to the screws. There was no evidence of hardware encroachment on the IAN or tooth roots.

CONCLUSION

Selection and placement of appropriate fixation devices, particularly the length of the bone screws, are crucial to avoid injury to the anatomic structures.

Relation of Mandibular Canal Discontinuity and IAN Paresthesia in Operated Cases of Mandibular Fracture

INTRODUCTION

Mandibular fractures are common in maxillofacial trauma, often requiring surgical intervention for optimal recovery. One critical concern during such procedures is the potential for nerve damage, specifically involving the mandibular canal. This study aims to investigate whether the presence of postoperative mandibular canal discontinuity is associated with an increased risk of nerve damage.

METHODOLOGY

A retrospective analysis was conducted on a cohort of 72 postoperative mandibular fracture patients. In total, 58 patients had entire mandibular canal continuity, while 14 showed discontinuity. Clinical records and follow-up data were examined to assess the occurrence of nerve injury. Statistical analysis was performed to determine the significance of any correlation.

RESULTS

Of the 14 patients with mandibular canal discontinuity, 9 (64.28%) exhibited paresthesia. In patients where mandibular canal continuity was maintained, 5 (8.62%) patients reported paresthesia. These results suggest a higher incidence of paresthesia in patients with mandibular canal discontinuity, albeit with a small sample size. Notably, only 3 patients in the discontinuity group did not show any sign of improvement, while the remaining patients in both groups demonstrated complete recovery in 6 months of follow-up period.

DISCUSSION

The findings suggest a potential link between mandibular canal discontinuity and an increased risk of paresthesia in postoperative mandibular fracture patients. It is hypothesized that discontinuity may lead to nerve compression, irritation, or direct damage during healing. The observed complete recovery in most patients, including those with paresthesia, highlights the potential for the nervous system to repair itself over a period of time. However, further studies with larger sample sizes are warranted to establish a more definitive correlation.

CONCLUSION

This study provides preliminary evidence that mandibular canal discontinuity may contribute to a higher incidence of paresthesia in postoperative mandibular fracture patients. Clinicians should be cautious when addressing mandibular fractures to minimize the risk of nerve damage, particularly in cases involving canal discontinuity. The encouraging trend of complete recovery among the majority of patients suggests a positive prognosis for nerve healing.

Inferior alveolar nerve dysfunction in mandibular fractures: a prospective cohort study

Objectives

To assess the prevalence and recovery of inferior alveolar nerve dysfunction (IAND) in mandibular fractures.

Materials and Methods

This was a prospective cohort study. Clinical neurosensory testing was done preoperatively and the IAND was categorized as mild, moderate or severe. Postoperatively, neurosensory testing was repeated at 1 day, 1 week, 1 month, 3 months and every 3 months thereafter.

Results

A total of 257 patients with 420 fractures were included in the study with a mean age of 31.7 years. Body fractures (95.9%) had the highest incidence of IAND, followed by the angle fractures (90.1%) and symphysis fractures (27.6%). The condyle and coronoid fractures did not have any IAND and hence were excluded from further study. After eliminating those cases, 232 patients remained in the study with 293 fractures. The overall prevalence of IAND in fractures occurring distal to the mandibular foramen was 56.3%. The changes until 1 week were minimal. From 1 month to 6 months, there was a significant reduction in the severity of IAND. A significant number of cases (60.0%) were lost to follow-up between 6 and 9 months. At 6 months, 23.9% of cases still had some form of IAND and 95.0% of the symphysis, 59.0% of the angle and 34.8% of the body fractures with IAND had become normal.

Conclusion

This study documents the reduction in the degree of severity of IAND in the first six months and provides the basis for future studies with longer periods of follow-up.

Does the Lag Time Between Injury and Treatment Play a Role in Recovery of Inferior Alveolar Nerve Neurosensory Disturbances Following Mandibular Body Fracture?

BACKGROUND

The lag time between injury and treatment (LTIT) plays an important role in reduction of complications in mandibular fractures. The aim of this study was to measure the effect of LTIT on recovery of the inferior alveolar nerve (IAN) neurosensory disturbances (NSDs) following surgical management of mandibular body fractures.

METHODS

This was a prospective cohort study. Patients who had a unilateral mandibular body fracture with paresthesia were studied. Paresthesia was evaluated by 2-point discrimination (TPD) test, brush stroke test and self-reporting before and 6 months after the surgical procedure.

RESULTS

Forty-five patients were studied. There was a correlation between LTIT and TPD test result and self-reported paresthesia at 6 months, postoperatively (P = 0.001). Fifteen patients (33.3%) had complete improvement in NSD 6 months after treatments (group 1) and 30 patients (group 2) had hyposthesia (N = 17, 37.77%) and paresthesia (N = 13, 28.88%). There was a significant difference in LTIT between groups 1 and 2 at 6 months postoperatively (P = 0.001). Cox regression model demonstrated the hazard ratio increased significantly for self-reported NSD when treatment was done 10 days after trauma (P = 0.001, confidence level = 95%).

CONCLUSION

It seems that conduction of open reduction with internal rigid fixation shortly after mandibular fracture may shorten the recovery time of NSDs of the IAN following mandibular body fractures.

Post-traumatic and postoperative neurosensory deficits of the inferior alveolar nerve in mandibular fracture: a prospective study

Objectives

We evaluated and recorded post-traumatic and postoperative neurosensory deficits of the inferior alveolar nerve (IAN) in mandibular fracture in order to identify associated risk factors.

Materials and Methods

This was a prospective cohort study composed of 60 patients treated for mandibular fracture. The primary study variable was the change between the post-traumatic IAN neurosensory examination score and the score after fracture reduction. Risk factors were categorized as demographic, anatomic, fracture displacement, and treatment. Appropriate descriptive and bivariate statistics were computed.

Results

Sixty patients with unilateral mandibular fracture reported within 24 hours of injury were evaluated over a one-year period. A post-traumatic neurosensory deficit was observed in 52 patients (86.7%), the percentage of which was reduced to 23.3% over the follow-up period. Abnormal postoperative neurosensory scores were significantly higher in angle fracture cases (33.3%) compared to body fracture cases (11.1%). When recovered and non-recovered neurosensory scores were compared by fracture location, 88.9% of body fracture cases showed significant recovery compared to 66.7% of mandibular angle fracture cases. Cases with less than 5 mm fracture displacement showed statistically significantly higher neurosensory recovery scores (90.6%) compared to those with more than 5 mm fracture displacement (60.7%).

Conclusion

Use of a miniplate with mono-cortical screws does not play a role in increasing IAN post-traumatic neurosensory deficit. Early management can reduce the chances of permanent neurosensory deficit. Mandibular fracture displacement of 5 mm or more and fracture location were found to be associated with an increased risk of post-traumatic IAN neurosensory score worsening.

Management of mandibular angle fractures using a 1.7 mm 3-dimensional strut plate

AIM

We report our experience with the use of 1.7 mm 3-dimentional (3D) strut plate for the management of mandibular angle fractures.

METHODS

This prospective study enrolled 15 patients in whom mandibular angle fractures were treated with 1.7 mm 3D plate using trans-buccal trochar. Patients were evaluated at 72 h, 2 weeks, 6 weeks and 12 weeks for fracture stability, occlusion, soft-tissue swelling, infection and post-operative inferior alveolar nerve damage. Other complications like wound dehiscence, non-union, mal-union and hardware failure were also assessed.

RESULTS

In the immediate post-operative period, fracture instability was seen in 1 (6.7%) patient which resolved by 2 weeks. Mild occlusal discrepancy was also noted in 1 (6.7%) patient. Wound dehiscence was seen in 5 (33.3%) patients and all resolved by local measures. 1 (6.7%) patient developed post-operative nerve paraesthesia. Immediate post-operative radiographic evaluation demonstrated optimal reduction in all cases with no inferior border gaping. No case of infection, hardware failure, non-union and mal-union was noted.

CONCLUSION

Within the limitations of the study, 1.7 mm 3D strut plate was found to be effective for management of non-communited mandibular angle fractures.

Evidence-based outcomes following inferior alveolar and lingual nerve injury and repair: a systematic review

The inferior alveolar nerve (IAN) and lingual (LN) are susceptible to iatrogenic surgical damage. Systematically review recent clinical evidence regarding IAN/LN repair methods and to develop updated guidelines for managing injury. Recent publications on IAN/LN microsurgical repair from Medline, Embase and Cochrane Library databases were screened by title/abstract. Main texts were appraised for exclusion criteria: no treatment performed or results provided, poor/lacking procedural description, cohort <3 patients. Of 366 retrieved papers, 27 were suitable for final analysis. Treatment type for injured IANs/LNs depended on injury type, injury timing, neurosensory disturbances and intra-operative findings. Best functional nerve recovery occurred after direct apposition and suturing if nerve ending gaps were <10 mm; larger gaps required nerve grafting (sural/greater auricular nerve). Timing of microneurosurgical repair after injury remains debated. Most authors recommend surgery when neurosensory deficit shows no improvement 90 days post-diagnosis. Nerve transection diagnosed intra-operatively should be repaired in situ; minor nerve injury repair can be delayed. No consensus exists regarding optimal methods and timing for IAN/LN repair. We suggest a schematic guideline for treating IAN/LN injury, based on the most current evidence. We acknowledge that additional RCTs are required to provide definitive confirmation of optimal treatment approaches.

Inferior alveolar and mental nerve injuries associated with open reduction and internal fixation of mandibular fractures: a Seven Year retrospective study

PURPOSE

To document adverse neurosensory changes in the inferior alveolar nerve (IAN) and mental nerve (MN) after surgical mandibular fracture treatment and to identify risk factors associated with these changes.

MATERIALS AND METHODS

A retrospective study of patients surgically treated for mandibular fractures. The primary study variable was the postoperative change in IAN/MN neurosensory examination after fracture fixation. Risk factors were categorized as demographic, anatomic, experience of the operator, fracture displacement and number of miniplates placed at each fracture site. Appropriate statistics were computed.

RESULTS

209 patients with 293 fractures were analysed. One hundred twenty fractures (41%) were located between the lingula and mental foramen, and 173 fractures (59%) were located distal to the mental foramen. Two hundred seventeen (41%) were displaced by 5 mm or more. In 38 fractures (13%), the IAN/MN neurosensory status worsened after treatment. In a multivariate model, fracture displacement, operator inexperience and two plate fixation were associated with a statistically significant risk (P ≤ 0.05) for postoperative deterioration of IAN/MN sensation.

CONCLUSION

Fixation with two miniplates, fracture displacement of 5 mm or more and operator inexperience were associated with an increased risk for deterioration of the IAN/MN neurosensory status after treatment of mandibular fractures.

Fixation of mandibular angle fractures with a 2.0-mm 3-dimensional curved angle strut plate

PURPOSE

The aim of this study was to evaluate our experience and complication rate with the use of a 3-dimensional 2.0-mm curved angle strut plate for mandibular angle fracture fixation.

PATIENTS AND METHODS

This was a retrospective evaluation of 37 patients with noncomminuted mandibular angle fractures fixated with a transorally placed curved 2.0-mm strut plate. Postoperative intermaxillary fixation was used in 5 patients for a mean period of 22 days. A nonchewing diet was prescribed for 6 weeks. Records were reviewed for demographic information, medical history, fracture characteristics, operative management, and complications.

RESULTS

Two patients developed infections requiring plate removal and reapplication of fixation. Both of these patients had a molar in the fracture line that was left in place during the first operation. One patient developed a mucosal wound dehiscence without consequence. After a mean follow-up period of 10 weeks, 39.4% of patients with a postinjury/pretreatment inferior alveolar nerve deficit reported a return to normal sensation. All patients who developed a sensory deficit as a result of surgery reported full recovery of sensation. A persistent sensory deficit appeared to be related to fracture displacement.

CONCLUSION

Fixation of noncomminuted mandibular angle fractures with a 2.0-mm curved angle strut plate was predictable. This plate is low in profile, strong yet malleable, facilitating reduction and stabilization at both the superior and inferior borders. Development of a postoperative infection appeared to be related to failure of removal of a molar in the fracture line. The infection rate of 5.4% found in this study compares favorably with that seen with reconstruction plates. Use of this plate did not appear to cause a permanent sensory deficit in this study.

Perioperative neurosensory changes associated with treatment of mandibular fractures

PURPOSE

The purpose of this study was to document perioperative neurosensory changes in the inferior alveolar nerve (IAN) after mandibular fracture treatment and to identify risk factors associated with these changes.

MATERIALS AND METHODS

This was a prospective cohort study composed of patients treated for mandibular fractures. The primary study variable was the change between the postinjury/pretreatment IAN neurosensory examination score and the score after fracture reduction. Risk factors were categorized as demographic, anatomic, and treatment. Appropriate descriptive, bivariate, and multivariate statistics were computed.

RESULTS

The cohort was composed of 61 patients with 97 fractured sides. Forty-seven fractures (49%) were located between the lingula and mental foramen, and 50 fractures (51%) were located distal to the mental foramen. Thirty-nine fractures (41%) were displaced by 5 mm or more. Abnormal preoperative IAN neurosensory examinations were documented in 81% of the fractured sides. Fifty-three fractures (54%) were treated by closed reduction and 44 (46%) by open reduction and internal fixation. In 82 fractures (85%), the IAN neurosensory score was unchanged or improved after treatment. In a multivariate model, preoperative neurosensory score, displacement, and treatment were associated with a statistically significant risk (P < or =.05) for postoperative deterioration of IAN sensation.

CONCLUSION

Open reduction and internal fixation, fracture displacement of 5 mm or more, and a normal preoperative IAN neurosensory examination were associated with an increased risk for deterioration of the IAN neurosensory score after treatment of mandibular fractures. Additional studies are indicated to determine long-term IAN neurosensory function after mandibular fracture treatment and the factors that affect prognosis.