Microsurgical Reconstruction of the Trigeminal Nerve

Relationship of the Degree of Nerve Exposure and Surgical Manipulation and Short-Term Neurosensory Disturbance Following Sagittal Split Ramus Osteotomy: A Prospective Study

BACKGROUND

Neurosensory disturbance (NSD) is a common complication after sagittal split ramus osteotomy (SSRO) due to inferior alveolar nerve (IAN) injury. The impact of intraoperative nerve manipulation on NSD remains debated.

PURPOSE

The purpose of this study was to evaluate the influence of IAN exposure and manipulation during SSRO on functional sensory recovery (FSR).

STUDY DESIGN

This was a single-center, prospective cohort study of 40 patients undergoing SSRO at Mahidol University from December 2020 to December 2021. The inclusion criteria were patients aged 20-34, ASA Class I-II. The exclusion criteria were patients with systemic bone disease, history of head and neck or neurological pathology, previous SSRO, or incomplete data collection.

PREDICTOR VARIABLE

Degree of intraoperative nerve manipulation was divided by the attending surgeon as follows; 1) Nerve fully encased in distal segment and not visible (NS); 2) Nerve encased in distal segment but partially visible (DS); and 3) Nerve partially encased in proximal segment and fully dissected free (PS).

OUTCOME VARIABLES

The area of interest was divided into the lip and chin. The primary outcome was time to FSR. The secondary outcome was subjective patient report, using a visual analogue scale, compared to FSR.

COVARIATES

The covariates were sex, age, skeletal diagnosis, degree of movement, and concomitant genioplasty/subapical procedure.

ANALYSES

Kaplan-Meier survival analysis, Cox proportional hazards regression, and Mcnemar test were utilized. P-value < .05 was significant.

RESULTS

In the lip, the median times to FSR were NS, 2 days; DS, 45 days; PS, 102 days. (Interquartile range: 77,127, 114, respectively) In the chin, the median times to FSR were NS, 23 days; DS, 92 days; PS, 87 days. (Interquartile range: 77, 161, 101, respectively.) Nerve manipulation significantly affected FSR in the lip and chin (P = .001, <0.001, respectively. Cox hazard ratios for DS and PS were lower compared to NS. Patients consistently reported more NSD compared to FSR as per Mcnemar test.

CONCLUSION AND RELEVANCE

After SSRO, FSR in the lip is prolonged when the IAN is partially encased in the proximal segment and released. This raises the question of the efficacy of surgically releasing a partially encased IAN.

Neurosensory recovery of inferior alveolar nerve gap reconstruction: a systematic review

Numerous procedures can potentially injure the inferior alveolar nerve during oral and maxillofacial surgery, eventually causing loss or alteration of local sensitivity. When its total rupture occurs, a conduit, such as an autogenous graft, can be used to join it. Due to the morbidity resulting from this technique, alternative forms of sensorineural repair have been investigated. This systematic review includes an electronic search of PubMed, Embase, LILACS, and Web of Science databases, in addition to a grey literature and manual search. Article selection was performed by two independent researchers following a predetermined inclusion criterion: human studies evaluating the regression of sensorineural disorders after any form of grafting (autogenous, allogeneic, and synthetic). Of the 789 studies, 648 were analysed. Only 11 articles met the eligibility criteria. After analysing the results, it was noted that regaining normal sensitivity was uncommon, but the majority of reconstructed nerves recovered their protective abilities. Allografts showed success rates similar to autogenous grafts, making them a viable alternative. However, clinical trials are still needed to provide solid evidence. Prognosis for sensory recovery was impacted by grafting time and patient age.

Development and Validation of Nerve-Targeted Bacteriochlorin Sensors

We report an innovative approach to producing bacteriochlorins (bacs) via formal cycloaddition by subjecting a porphyrin to a trimolecular reaction. Bacs are near-infrared probes with the intrinsic ability to serve in multimodal imaging. However, despite their ability to fluoresce and chelate metal ions, existing bacs have thus offered limited ability to label biomolecules for target specificity or have lacked chemical purity, limiting their use in bio-imaging. In this work, bacs allowed a precise and controlled appending of clickable linkers, lending the porphyrinoids substantially more chemical stability, clickability, and solubility, rendering them more suitable for preclinical investigation. Our bac probes enable the targeted use of biomolecules in fluorescence imaging and Cerenkov luminescence for guided intraoperative imaging. Bacs' capacity for chelation provides opportunities for use in non-invasive positron emission tomography/computed tomography. Herein, we report the labeling of bacs with Hs1a, a (NaV1.7)-sodium-channel-binding peptide derived from the Chinese tarantula Cyriopagopus schmidti to yield Bac-Hs1a and radiolabeled Hs1a, which shuttles our bac sensor(s) to mouse nerves. In vivo, the bac sensor allowed us to observe high signal-to-background ratios in the nerves of animals injected with fluorescent Bac-Hs1a and radiolabeled Hs1a in all imaging modes. This study demonstrates that Bac-Hs1a and [64Cu]Cu-Bac-Hs1a accumulate in peripheral nerves, providing contrast and utility in the preclinical space. For the chemistry and bio-imaging fields, this study represents an exciting starting point for the modular manipulation of bacs, their development and use as probes for diagnosis, and their deployment as formidable multiplex nerve-imaging agents for use in routine imaging experiments.

The Trigeminal Nerve Injury

Trigeminal nerve branches are never far from the operating field of the oral and maxillofacial surgeon. Increasingly the surgeon is required to provide accurate diagnosis and grading of trigeminal nerve injury, and surgical management by oral and maxillofacial surgeons will become common. Although trauma and ablative procedures for head and neck pathology can cause injuries, dentoalveolar surgical procedures remain an important cause of injury to the fifth cranial nerve, with the third division being the main branch affected. Oral and maxillofacial surgeons should be aware of strategies of avoiding iatrogenic injury, and know when referral and surgical management are appropriate.

Anatomical study: the potential movability of the inferior alveolar nerve

OBJECTIVE

Nerve repair and repositioning are procedures for treating and avoiding injury to the inferior alveolar nerve during oral and maxillofacial surgery. The present study aimed to examine how the mobility of the inferior alveolar neurovascular bundle (IAB) changes with or without removing the bone around the mental foramen (MF).

STUDY DESIGN

Six fresh-frozen cadavers (11 sides) were dissected in this study. Osteotomy in the buccal cortical bone was performed from 5 mm posterior to the MF to the distal edge of the second molar with a high-speed drill and osteotome. Next, the distance from the lateral surface of the buccal cortical bone to the retracted IAB was measured with and without removing the bone around the MF.

RESULTS

The distance from the lateral surface of the buccal cortical bone to the retracted IAB without removing the bone around the MF was 0 mm on all sides. After removing the bone, the mean distance changed by 4.71 ± 1.41 mm (range 2.83-7.90). There was no statistically significant difference between the right and left sides.

CONCLUSIONS

The results of this study support removing the bone around the MF for increased mobility of the IAB.

Our experience in the surgical management of craniofacial fibrous dysplasia: what has changed in the last 10 years?

The mainstay of treatment of craniofacial dysplasia (CFD) remains surgery once clinical observation has been excluded. Nevertheless, disagreement remains about the type of surgical intervention (remodelling versus radical resection). The aim of this paper is to present our experience until 2013 comparing CFD management between 1980 and 2002 and between 2003 and 2013 and to propose our surgical algorithm. From January 2003 to December 2013, 41 new patients (18 males and 23 females) with histologically demonstrated CFD presented to our Department. Data were compared with those of 95 patients observed and/or treated between 1980 and 2002. Considering the last period, we noted that observation (26/41 patients) was the most used method; radical resection was performed in most cases (8/15 patients), but in proportion the numbers of patients undergoing bone shaving has increased (6% between 1980 and 2002 vs 15% between 2003 and 2013), while a decrease in the number of patients undergoing excision was seen (63% between 1980 and 2002 vs. 19% between 2003 and 2013). On this basis, we believe that radical resection is the only technique to obtain resolution of fibrous dysplasia. Wait-and-see is indicated in case of stable lesions. Reconstructive techniques allow obtaining adequate aesthetical and functional results; nevertheless, in most cases adjunctive surgical refinements are required and recovery time is higher than with surgical shaving, so that most patients prefer to perform remodelling. Nevertheless, in case of aggressive lesions radical resection is mandatory, except in paediatric patients with residual large defects in which it can be acceptable to try to resolve symptoms via bone shaving, reserving more aggressive treatments in case of relapse or after skeletal maturity.

Surgical management of damaged inferior alveolar nerve caused by endodontic overfilling of calcium hydroxide paste

AIM

To evaluate the neurosensory outcome of management of damaged inferior alveolar nerves caused by endodontic overfilling and to assess the efficacy of delayed surgical intervention.

METHODOLOGY

Nine patients who underwent surgical removal of extruded endodontic material were included. All patients were evaluated for neurosensory function using a set of standardized tests. The outcome of surgical intervention was evaluated through patient interview and quantitative statistical analysis.

RESULTS

Surgical procedures included foreign body removal, microsurgical external/internal decompression, excision of neuroma followed by nerve repair, and excision of damaged nerve segment with interpositional nerve graft. Seven of the nine patients had significant improvement according to the follow-up neurosensory assessment. Four patients reported significant improvement, three patients reported mild improvement and two patients reported no appreciable improvement in the Visual Analog Scale (VAS). Two patients who reported no appreciable improvement in VAS also did not achieve FSR. In these patients, calcium hydroxide was spread widely along the IAN and a surgical approach was obtained via sagittal spit osteotomy. The mean time to reach FSR was 222.7 (±41.8) days with a range of 106-397 days. In the early repair group who received surgery within 60 days, three out of five patients achieved FSR in a mean time of 198.0 (±76.2) days. The mean time to FSR in all four subjects who received surgical attention over 60 days after injury was 241.3 (±139.8) days with a range of 106-397 days. As all four cases in the late repair group with limited amount of nerve injury achieved FSR, only 3 of 5 early repair cases with wide-spread injury achieved a similar outcome.

CONCLUSION

The results of this case series confirmed the notion that surgical management of the inferior alveolar nerve is effective in the treatment of nerve injuries caused by endodontic extrusion of calcium hydroxide paste. Delayed surgical repair of the inferior alveolar nerve can be indicated and helpful for the neurosensory recovery of damaged IAN, however, the surgical management was less effective in case of widespread nerve injuries.