Comparison of prognosis in two methods for the lingual nerve repair: direct suture with vein graft cuff and collagen allograft method

Evaluating Lingual Nerve Repair Outcomes: A Systematic Review

PURPOSE

The lingual nerve (LN) is susceptible to injury during oral and maxillofacial procedures, leading to neurosensory deficits. Advances in microsurgical techniques necessitate a comprehensive review of overall effectiveness and influencing factors.

METHODS

A systematic review was performed via Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify studies. Inclusion criteria were full text availability, studies written in english, and studies published after 2000 reporting LN repair. The primary outcome was sensory improvement defined via functional sensory recovery (FSR) or neurosensory testing (NST). Sex, time from injury to repair, method of repair, and graft length were examined to see if each influenced outcomes.

RESULTS

A sample of 786 subjects across 17 studies was examined. Most patients were female (73.3%) and suffered injuries from third molar extractions (72.8%). Of the studies, 10 defined improvement by FSR with a total of 88.8% (500/563) of nerves achieving such. Of those achieving FSR, 91% did so within a year. The remaining 7 studies defined sensory improvement by individually setting various NST thresholds, with the combined improvement rate being 88.6% (203/229). Positive outcomes were achieved with graft lengths up to 70 mm. Results on time to repair were mixed. The methods of repairs were not different based on statistical analysis short of performing an equivalence trial.

CONCLUSION

Conclusions made from studies using FSR were similar to studies using NST, meaning the method of measuring outcomes does not seem to be a confounder. FSR is the superior scale due to being objective and standardized. LN repair produced high rates of sensory improvement, which is expected to occur within 1 year postoperative. Sex and graft length did not influence outcomes. More research is needed to determine the effect of time to repair on efficacy. Most methods of repair produced similar outcomes, suggesting multiple valid techniques exist.

Assessing the Efficacy of Allogeneic Nerve Grafts in Trigeminal Nerve Repair: A Systematic Review

PURPOSE

Our primary objective was to assess the efficacy of allogeneic nerve grafts in inferior alveolar nerve or lingual nerve repair. We hypothesized that using allogeneic nerve grafts would be effective, as evidenced by achieving high rates of functional sensory recovery (FSR). Additionally, we looked if sex, time from injury to repair, etiology of nerve damage, and graft length affected outcomes.

METHODS

A systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was conducted. PubMed and Scopus databases were searched using specific search strategies to generate eligible studies. Inclusion criteria encompassed studies reporting use of allogeneic grafts, assessing FSR using either Medical Research Council Scale or Neurosensory Testing, and published within the past 15 years.

RESULTS

Across 10 studies conducted between 2011 and 2023, analysis was performed on 149 patients and 151 reconstructed nerves. Allogeneic nerve grafts showed an average FSR rate of 88.0%. Kaplan-Meier analysis of time to FSR postoperatively revealed that of those achieving FSR, 80% achieved it within 6 months and 98% achieved it by 1 year. The mean graft length was 29.92 mm ± 17.94 mm. The most common etiology for nerve damage was third molar extractions (23.3%). Sex distribution among patients revealed that 85 were female (57.0%) and 64 were male (43.0%).

CONCLUSION

Our primary hypothesis was supported as nerve allografts achieved high rates of FSR. FSR was achieved in normative timeframes, which is 6 to 12 months postoperatively. Furthermore, allografts reduced the risk of posttraumatic trigeminal neuropathy. Time from injury to repair, graft length, etiology of nerve damage, and sex did not affect FSR. As the assessed variables in our study did not affect outcomes, there needs to be a more nuanced approach to understanding and addressing various factors influencing sensory recovery.

Application of Tinel's test combed with clinical neurosensory test distinguishes spontaneous healing of lingual nerve neuropathy after mandibular third molar extraction

BACKGROUND

Extraction of the mandibular third molar, the most frequent and important surgical procedure in the clinical practice of oral surgery, is associated with the risk of injury of the lingual nerve. Neuropathy of the lingual nerve poses diagnostic challenges regarding the transient or permanent nature of the injury. No consensus or criteria have been established regarding the diagnosis of lingual nerve neuropathy. We applied both Tinel's test and clinical neurosensory testing together, which can be easily used at the bedside in the early stages of injury. Therefore, we propose a new method to differentiate between lesions with the ability to heal spontaneously and those that cannot heal without surgery.

RESULTS

Thirty-three patients (29 women,  4 men; mean age, 35.5 years) were included in this study. For all patients, the median interval between nerve injury and initial examination was 1.6 months and that between nerve injury and the second examination before determining the need for surgical management was 4.5 months. The patients were assigned to either group A or B. The spontaneous healing group (group A, n = 10) revealed a tendency for recovery within 6 months after tooth extraction. In this group, although there were individual differences in the degree of recovery, a remarkable tendency for recovery was observed based on clinical neurosensory testing in all cases. None of the patients were diagnosed with allodynia. In seven cases, the Tinel test result was negative at the first inspection, and in three cases, the result changed to negative at the second inspection. Conversely, in group B(n = 23), no recovery trend was observed with regard to clinical neurosensory testing, and nine patients had allodynia. Further, the Tinel test result was positive for all patients in both examinations.

CONCLUSIONS

Our findings indicate that in case of transient lingual nerve paralysis, clinical neurosensory testing findings deteriorate immediately after tooth extraction and gradually recover, while Tinel's test shows a negative result. Using Tinel's test and clinical neurosensory testing together enabled early and easy identification of the severity of the lingual nerve disorder and of lesions that would heal spontaneously without surgical management.