Mental Nerve Injury Research Articles

Transoral endoscopic thyroid surgery via the tri-vestibular approach with a hybrid space-maintaining method: A preliminary report.

Transoral endoscopic thyroid surgery has been introduced in a few institutions. The purpose of this study was to present an innovative hybrid space-maintaining method for the tri-vestibular approach. Eighteen consecutive patients underwent transoral endoscopic thyroidectomy. Three incisions were made in the vestibule. The surgical space was maintained with CO2 insufflation along with a suspension device. Thyroidectomy and central neck dissection (CND) were performed safely and effectively. The mean operation time was 124 minutes for a simple lobectomy, subtotal thyroidectomy, and isthmectomy in 8 patients, 172 minutes for hemithyroidectomy with ipsilateral CND in 8 patients, and 205 minutes for total thyroidectomy with ipsilateral CND in 7 patients. Transient superior laryngeal nerve (SLN) injury occurred in 3 patients and transient mental nerve injury was found in 1 patient. No evidence of recurrence or metastasis was found at follow-up. This approach brings satisfactory cosmetic effect along with minimal invasion. Further study is needed to verify its validity.

Safety and Outcomes of the Transoral Endoscopic Thyroidectomy Vestibular Approach

Natural orifice transluminal endoscopic surgery thyroidectomy is a novel approach to avoid surgical scars. To compare the safety and outcomes of the transoral endoscopic thyroidectomy vestibular approach (TOETVA) with those of open thyroidectomy (OT). This study retrospectively reviewed all TOETVA and OT operations performed from April 1, 2014, through August 31, 2016, at Police General Hospital, Bangkok, Thailand. All patients who underwent TOETVA and patients who underwent OT were included. Exclusion criteria were (1) previous neck surgery, (2) substernal goiter, (3) lymph node or distance metastasis, and (4) suspicious invasion to the adjacent organs. Propensity score matching was conducted to reduce selective bias. Operative time, blood loss, and complications related to thyroid surgery. Of the 425 patients who underwent transoral endoscopic thyroidectomy (mean age, 35.3 [12.1] years; age range, 16-81 years; 389 [92.2%] female), 422 successfully were treated with the TOETVA; 3 patients were converted to a conventional operation because of bleeding. Twenty-five patients (5.9%) had transient recurrent laryngeal nerve palsy, and 46 (10.9%) had transient hypoparathyroidism. None had permanent recurrent laryngeal nerve palsy or permanent hypoparathyroidism. Three patients (0.7%) had transient mental nerve injury; all cases resolved by 4 months. One patient developed postoperative hematoma treated by OT. Twenty patients (4.7%) had seroma treated by simple aspiration. Operative time was longer for the TOETVA compared with the OT group (100.8 [39.7] vs 79.4 [32.1] minutes, P = 1.61 × 10-10). The mean (SD) visual analog scale score for pain was lower in the TOETVA group (1.1 [1.2] vs 2.8 [1.2], P = 2.52 × 10-38). Estimated mean (SD) blood loss (36.9 [32.4] vs 37.6 [23.1] mL, P = .43) and rate of complications (45 of 216 [20.8%] vs 38 of 216 [17.6%], P = .41) were not significantly different in the TOETVA vs OT group. The TOETVA was performed as safely as OT, requires only conventional laparoscopic instruments, and avoids incisional scars; thus, the approach may be an option for select patients.

A Survey of the Opinion and Experience of UK Dentists Part 3: An Evidence-Based Protocol of Surgical Risk Management Strategies in the Mandible.

Implant surgery in the mandible can cause serious complications that can be life threatening. The incidence and cause of iatrogenic trigeminal nerve injury (TNI) related to dental implant surgery was investigated in a survey of the opinion and experience of the UK dentists and reported by the authors in part 1 of this series of articles. Part 2 reported on the risk assessment and management of implant-related inferior alveolar nerve (IAN), mental nerve (MN), and lingual nerve (LN) injuries. This article evaluates the significance of these findings and recommends an evidence-based protocol of risk management strategies to reduce the risk of TNI related to dental implant surgery. A survey was distributed among 405 dentists attending an Association of Dental Implantology (ADI) congress, of which 187 completed the survey. In this study, the strategies to manage the risk of TNI included unilateral staging of implant placement (57%) and identification the MN when placing implants (43%). Twelve percent used drill stops when operating in the mandible. Nineteen dentists used steroids (eg, dexamethasone) routinely preoperatively and postoperatively. Twenty-six dentists used basic cone beam computed tomography minimally invasive techniques, and 70% encountered a large anterior loop of the IAN. Most dentists (76%) allowed a 2- to 4-mm safety zone radiologically above the IAN when placing implants, and over half of the responders (56%) used implants that were 10 mm in length. Given the elective nature of implant surgery, TNI should be fully avoidable. The evidence suggest that TNI can be minimized with meticulous attention to accurate assessment and surgical planning as well as carrying out the surgery with a high degree of precision. In part 3 of their series of articles, the authors presented an evidence-based protocol that comprises preoperative, intraoperative, and postoperative risk management strategies for dental implant surgical procedures in the mandible.

Transoral endoscopic surgery for papillary thyroid carcinoma: initial experiences of a single surgeon in South Korea.

PurposeThe transoral endoscopic thyroid surgery vestibular approach (TOETVA) is one of the newest techniques which do not result in an anterior neck scar. We report herein our initial experience with TOETVA and its short-term outcomes in patients with papillary thyroid carcinoma (PTC).MethodsThis case series consisted of all consecutive patients who underwent TOETVA in our institution between August 2016 and June 2017. Indications for TOETVA were an fine needle aspiration-confirmed PTC or follicular neoplasm, an intrathyroidal tumor with a diameter of less than 2 cm, and no clinical evidence of central or lateral lymph node metastasis. A total of 20 patients underwent TOETVA and we retrospectively reviewed clinicopathologic data and short-term postoperative outcomes.ResultsAmong the 20 TOETVA cases, 7 were total thyroidectomy, 12 were lobectomy and 1 was wide isthmusectomy. Mean age was 50.8 years and mean operation time was 152 ± 51.4 minutes. Tumor size ranged from 0.2–1.4 cm and the mean size of harvested central lymph nodes was 2.8 (range, 0–10). Neither mental nerve injury nor surgical site infection occurred. One patient had transient vocal cord palsy and 1 patient developed a neck seroma. Among 7 total thyroidectomy patients, 3 patients developed transient hypocalcemia.ConclusionTransoral thyroid surgery could be an alternative surgical option for some PTC patients.

Transoral robotic thyroidectomy: lessons learned from an initial consecutive series of 24 patients.

Transoral thyroid surgery is an ideal method for minimally invasive thyroidectomy, as there is less flap dissection during the procedure and no postoperative scars. Nonetheless, technical obstacles have precluded the wide dissemination of this procedure. We present the surgical procedures and outcomes of transoral robotic thyroidectomy (TORT). From September 2012 to June 2016, we performed TORT at Korea University Hospital. We used three intraoral ports and a single axillary port for the system's four robotic arms. The surgical outcomes were retrospectively reviewed. Twenty-four female patients (mean age 39.6±11.6years; mean tumor size 1.0±1.3cm) underwent unilateral thyroid lobectomies with or without ipsilateral central neck dissection. Twenty patients had papillary thyroid carcinomas (PTC), three had benign nodules, and one had a follicular thyroid carcinoma. The mean surgical time was 232±41min; the mean hospital stay was 3.3±0.8days. The number of retrieved central lymph nodes in the PTC patients was 4.7±3.2. There were no reports of transient or permanent vocal cord palsy, recurrence, or mortality during the median follow-up period of 16.8months. Paresthesia of the lower lip and the chin due to mental nerve injury was observed in nine of the first 12 patients (six transient, three permanent), but no further reports of paresthesia were recorded after patient 12, when the locations of the intraoral incisions were modified. TORT is feasible and safe for selected patients after technical refinements, and can be a potential alternative approach for scarless thyroid surgery.

Transoral endoscopic thyroidectomy vestibular approach (TOETVA): indications, techniques and results.

The Transoral Neck Surgery (TONS) Study Group was established at the 1st International Thyroid NOTES Conference in February 2016 with the intention of standardizing and refining thyroid NOTES techniques, including both transoral endoscopic and robotic thyroidectomy approaches. Herein, the authors report the modification of indications, preparation, and step-by-step explanations for operative techniques, as well as results and postoperative care for transoral endoscopic thyroidectomy vestibular approach (TOETVA). Between February 2015 and December 2015, a total of 200 patients comprising 8 males (4%) and 192 females (96%) underwent TOETVA using 3 laparoscopic ports inserted at the oral vestibule. Of these patients, 111 presented with single thyroid nodules (55.5%), while 66 patients had multinodular goiters (33%), 12 had Graves' disease (6%) and 11 had papillary microcarcinoma (5.5%). The CO2 insufflation pressure was maintained at 6mmHg. Each surgery was performed using laparoscopic instruments and ultrasonic devices. TOETVA was performed on 200 consecutive patients. No conversion to conventional open surgery was necessary. Average tumor size was 4.1±1.78cm (1-10cm). Median operative time was 97±40.5min (45-300min). Median blood loss was 30±46.25mL (6-300mL). Mean visual analog scale measurements were 2.41±2.04 (2-7), 1.17±1.4 (0-5), and 0.47±0.83 (0-3) on the first, second, and third days, respectively. Temporary hoarseness and hypoparathyroidism occurred in 8 patients (4%) and 35 patients (17.5%), respectively. No permanent hoarseness or hypoparathyroidism occurred. Mental nerve injury occurred in 3 patients (1.5%). One patient (0.5%) developed a post-operative hematoma that required open surgery. No infection was identified. TOETVA was shown to be safe and feasible with a reasonable surgical duration and minimal pain scores. This approach shows promise for those patients who are motivated to avoid a neck scar.

Comparison of Ozone and Photo-Biomodulation Therapies on Mental Nerve Injury in Rats

This study compared photo-biomodulation (PBM) and ozone therapy (OT) for mental nerve injury by counting Schwann cells (SCs) and fasciculated nerve branches and measuring fascicular nerveareas. The effects of OT and PBM on mental nerve injury were evaluated. Mental nerves of 27 rats were partly sutured and allocated into 3 groups. Group 1 received no treatment, group 2 received OT, and group 3 received PBM. The number of fascicules beyond nerve branches and the number of SCs before and after nerve injury were evaluated histologically. A better healing pattern was observed in the treatment groups. The number of SCs was markedly larger in the OT and PBM groups than in the control group. Oral and maxillofacial surgeons should be familiar with the differential diagnosis, prevention, and management of neurosensory disturbances. This study provides insights into the management of neurosensory disturbances related to mental nerve injury using OT and PBM. This study clearly suggests that OT and PBM are promising novel methods for the treatment of mental nerve injury.

A Survey of the Opinion and Experience of UK Dentists: Part 2: Risk Assessment Strategies and the Management of Iatrogenic Trigeminal Nerve Injuries Related to Dental Implant Surgery.

Dental implant-related iatrogenic injuries are proportionally increasing with dental implant surgery. This study assessed the experience of implant-related trigeminal nerve (TG) injuries among UK dentists. Risk management strategies and management of implant-related inferior alveolar nerve (IAN), mental nerve (MN), and lingual nerve injuries were investigated. A survey was distributed among 405 dentists attending an Association of Dental Implantology (ADI) congress, of which 187 completed the survey. Most dentists (76% of 134 responses) allowed a 2 to 4 mm safety zone radiologically above the IAN when placing implants, and over half of the responders (56%) used implants that were 10 mm in length. The most frequent precautionary measure used by 73 (80%) responders was antibiotic coverage routinely to reduce the risk of infection when placing grafts in the posterior mandible. Other precautionary measures included unilateral staging of implant placement (57%), and 43% always identified the MN when placing implants. Nineteen dentists used steroids (eg, dexamethasone) routinely preoperatively and postoperatively. Twenty-six dentists used basic cone-beam CT (CBCT) minimally invasive techniques, and drill stops during implant placement were used by 14 responders. Although it is not highly recommended, steroids were used to manage the neuropathic pain and discomfort experienced by patients with IAN injuries in 40% of cases. Further training of dentists undertaking implant surgery is required so that they acquire up-to-date and evidence-based knowledge and skills in the prevention, diagnosis, and management of dental implant-related TG injuries. This training should also involve the justification and interpretation of CBCTs.

Molecular, cellular and behavioral changes associated with pathological pain signaling occur after dental pulp injury.

Persistent pain can occur after routine dental treatments in which the dental pulp is injured. To better understand pain chronicity after pulp injury, we assessed whether dental pulp injury in mice causes changes to the sensory nervous system associated with pathological pain. In some experiments, we compared findings after dental pulp injury to a model of orofacial neuropathic pain, in which the mental nerve is injured. After unilateral dental pulp injury, we observed increased expression of activating transcription factor 3 (ATF3) and neuropeptide Y (NPY) mRNA and decreased tachykinin precursor 1 gene expression, in the ipsilateral trigeminal ganglion. We also observed an ipsilateral increase in the number of trigeminal neurons expressing immunoreactivity for ATF3, a decrease in substance P (SP) immunoreactive cells, and no change in the number of cells labeled with IB4. Mice with dental pulp injury transiently exhibit hindpaw mechanical allodynia, out to 12 days, while mice with mental nerve injury have persistent hindpaw allodynia. Mice with dental pulp injury increased spontaneous consumption of a sucrose solution for 17 days while mental nerve injury mice did not. Finally, after dental pulp injury, an increase in expression of the glial markers Iba1 and glial fibrillary acidic protein occurs in the transition zone between nucleus caudalis and interpolaris, ipsilateral to the injury. Collectively these studies suggest that dental pulp injury is associated with significant neuroplasticity that could contribute to persistent pain after of dental pulp injury.

The Appropriate Retractors for Genioplasty.

Mental nerve (MN) injury is the most common complications of genioplasty; to protect the MN and oral mucosa, the authors invent and validate the appropriate retractors for genioplasty, and which can avoid the skin and mucous membrane of the lower lip, chin, and the vestibular gingiva of the mandibular incisor from paresthesia or dysesthesia. The patent application for the appropriate retractors for genioplasty is already submitted (Patent No 201610164563.3, China). The retractors provide a better surgical visual field and improve the operation efficiency while reducing the risk of surgery. And the method is simple, safe, efficient, and laborsaving.

A Survey of the Opinion and Experience of UK Dentists: Part 1: The Incidence and Cause of Iatrogenic Trigeminal Nerve Injuries Related to Dental Implant Surgery.

Dental implant-related iatrogenic trigeminal nerve (TG) injuries are proportionally increasing with dental implant surgery. This study, which is presented in greater detail over a series of articles, assessed the experience of implant-related TG nerve injuries among UK dentists. Incidence and cause of inferior alveolar nerve (IAN), mental nerve (MN), and lingual nerve (LN) injuries, together with preoperative assessment and the consent process, are presented in this article. A survey was distributed among 405 dentists attending an Association of Dental Implantology congress in the United Kingdom, of which 187 completed the survey. Most responding dentists were full-time general practitioners. Implant dentistry training was predominately through industry-organized courses. Eighty dentists encountered implant-related IAN injuries, whereas 8 encountered LN injuries. Inaccurate radiological identification of the IAN/MN and their anatomical variations (48%) were seen to be the most frequent cause of TG injuries. Disclosure of the relative risk and benefits of alternative implant treatment strategies as part of the informed consent process was not deemed to be essential by 47 (25%) of the participants. Inadequate radiological assessment was the most common cause of TG nerve injury. The use of small field of view cone beam computer tomography (CBCT) is therefore recommended when placing implants in the posterior mandible. Implant surgeons should acquire evidence-based skills in the prevention, diagnosis, and management of TG nerve injury as well as specific training on justification and interpretation of CBCT scans.

A Simplified, Reliable Approach for Advancement Genioplasty.

Advancement genioplasty is a versatile procedure able to address both functional and cosmetic issues. It is commonly performed by oral surgeons and less so by facial plastic and plastic surgeons, presumably because of its inherent risks. To present our technique for advancement genioplasty and our aesthetic and functional outcomes. A retrospective review was conducted of the medical records of 126 patients who had undergone advancement genioplasty with our modified technique in a private practice setting from September 1997, through September 2014. Our analysis was performed between January and March 2015. Description of technique and evaluation of complication rates, improvement in sleep apnea symptoms, and patient satisfaction. The 126 patients had a mean age of 39.8 years. There were 81 male and 45 female patients. The overall complication rate was 6.3% (8 of the 126 patients). Complications included plate extrusion in 2 patients, infection in 2 patients, mental nerve injury in 3 patients, and tooth root injury in 1 patient. Patients were satisfied with the aesthetic result of the procedure, which also produced an improvement in obstructive sleep apnea in 82 of 89 (92%) patients with sleep apnea. Advancement genioplasty is a valuable tool that can address both functional and aesthetic issues. The technique presented here allows safe, reliable, and effective execution of the procedure. 3.

Anatomical Variations and Biological Effects of Mental Foramen Position in Population of Saudi Arabia

Background: Understanding the anatomical variations in the position of the mental foramen is significant for different dental procedures. This study identified the position of the mental foramen among a Saudi population in the western region of Saudi Arabia. Methods: A total of 950 panoramic radiographs (PAN) were selected from a total of 1195 radiographs. The mental foramen location was determined by drawing imaginary lines parallel with the long access of the lower premolars and mesial root of the first molar on the same side. The mental foramen location was then classified into six classes (Class I-VI). Results: In the Saudi population, more than half of the mental foramina were located between the lower premolars (Class III, 57.89%), followed by class IV (41.70%) of the mental foramen was located under the second premolar apex. None of the radiographs showed that the mental foramen was located in front of the first premolar (Class I). Conclusion: For successful and secure mental nerve blocking, the anesthetic solution should be injected between the first and second premolars or under the lower 2nd premolar in the Saudi population. Additionally, caution should be taken when operating close to these areas to avoid mental nerve injury.

Unilateral Absence of Mental Foramen with Surgical Exploration in a Living Human Subject.

The mental foramen (MF) is an important anatomic landmark of the mandible, in which the somatic afferent sensory nerve of the mandibular nerve emerges as mental nerve and blood vessels. The identification and actual location of MF are important in order to avoid sensory dysfunction or paresthesia due to mental nerve injury. In the literature there are some rare reports on the anatomical variations of the MF such as its location or presence of accessory foramina. The present report describes the absence of mental foramina on the left side of the mandible, as detected by cone-beam computed tomography before impacted tooth removal and observed directly during surgery.

Transoral Endoscopic Thyroidectomy Vestibular Approach: A Series of the First 60 Human Cases.

Natural orifice transluminal endoscopic surgery has been adopted for thyroid surgery because of its potential for scar-free operation. However, the previous technique still has some limitations. Thus, we present our initial experience in transoral endoscopic thyroidectomy vestibular approach (TOETVA). From April 2014 to January 2015, we used a three-port technique through the oral vestibule, one 10-mm port for laparoscope and two additional 5-mm ports for instruments. The CO2 insufflation pressure was set at 6mm Hg. An anterior cervical subplatysmal space was created from the oral vestibule down to the sternal notch. The thyroidectomy was done endoscopically using conventional laparoscopic instruments and an ultrasonic device. A series of 60 procedures were accomplished successfully. 42 patients had single-thyroid nodules, and a lobectomy was performed. 22 patients had multinodular goiters and two patients had Graves' disease, with total thyroidectomy or Hartley-Dunhill procedures performed. Two had papillary thyroid carcinoma, and total thyroidectomy with central node dissection was performed. The median operative time was 115.5min (range 75-300min). The median blood loss was 30mL (range 8-130mL). Two patients experienced a transient hoarseness, which was resolved within 2months. One patient experienced a late postoperative hematoma, which was treated conservatively. No mental nerve injury or infections were found. The patients were discharged in an average of 3.6days (range 2-7days) postoperatively. TOETVA is safe and feasible, resulting in no visible scarring. This technique may provide a method for ideal cosmetic results.

Study of Number, Shape, Size and Position of Mental Foramen in Bangladeshi Dry Adult Human Mandible

Context: Paralysis of the mental nerve is one of the principal complications of surgery of the mandibular canal and mental foramen region. Therefore, identification of mental foramen is important for dental surgeons in nerve block and surgical procedures like apico curettage of mandibular premolars, amalgam filling, peridental surgery etc. to avoid injury to neurovascular bundle. Verification of the existence of accessory mental foramina would prevent accessory mental nerve injury during periapical surgery. Therefore, prior knowledge of morphology and morphometry of mental and accessory mental foramen to particular block may cause effective mental block anaesthesia. Besides this, mental foramen and accessory mental foramen have been found to vary in position in different ethnic groups. So, it is important to study the morphology and morphometry of mental foramen. Materials and Methods: A cross-sectional, analytical type of study was conducted in the Department of Anatomy, Dhaka Medical College using dried adult human mandibles of unknown sexes. Number and shapes of mental foramen and accessory mental foramen were observed. Size and position were determined by using digital sliding calipers. Result: Mental foramen was present in all one hundred and eighty five (185) observed mandibles and it was bilateral. Accessory mental foramen was present in 1.62% on left side while on right side, it was 0.54%. None of the mandibles presented with bilateral accessory mental foramen. Shape was predominantly oval with 55.7% on right side and 53.5% on left side while it was round in 44.3% on right side and 46.5% on left side. Mental foramen was commonly located between 1st and 2nd premolar, below 2nd premolar and between 2nd premolar and 1st molar. Conclusion: Prior knowledge of mental foramen variations helps surgeon in planning surgery in that region to avoid nerve damage and also for effective mental nerve block anaesthesia. DOI: http://dx.doi.org/10.3329/bja.v11i1.20501 Bangladesh Journal of Anatomy, January 2013, Vol. 11 No. 1 pp 7-10

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

PurposeTo 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 methodsA 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. Results209 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. ConclusionFixation 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.

Single stage surgery for contouring the prominent mandibular angle with a broad chin deformity: En-bloc Mandibular Angle-Body-Chin Curved Ostectomy (MABCCO) and Outer Cortex Grinding (OCG)

BackgroundVarious surgical options are reported to address the Asian 'squared face', characterized by a prominent mandibular angle (PMA) associated with an oversized chin deformity; but shortcomings lie in the requirement of multi-stage procedures with the risk of further revision surgery. We have developed a single-stage “Mandibular Angle-Body-Chin Curved Ostectomy (MABCCO) and Outer Cortex Grinding (OCG)” surgical technique to shorten the period of the surgical treatment and minimize the inherent surgical risks in the multi-staged procedures. MethodsA retrospective study involving patients (n = 36) presented with prominent mandibular angle and an oversized chin who underwent the operation described from 2010 to 2012 with at least 12 months of follow-up. The surgical and aesthetic outcomes were evaluated through clinical assessment, photography, imaging analysis including preoperative and post-operative patient satisfaction rates. ResultsAll the patients were satisfied with the improvement in their appearance following surgery; specifically the 'smoothness' of the mandibular inferior border with no 'second mandibular angle'. The width of the mandible was reduced with G–G distance reduced from 119.9 mm ± 3.9–109.7 mm ± 3.5 (p < 0.05). A significant preoperative and post-operative gonial angle (G-A) was found at the left (110.7° ± 9.6 vs 139.9° ± 11.5, p < 0.05) and right side of mandible (111.3° ± 10.7 vs 140.7° ± 11.8, p < 0.05). There was no iatrogenic inferior alveolar nerve or mental nerve injury and a stable aesthetic outcome beyond the first year. ConclusionWe demonstrated favourable surgical and aesthetic outcomes with our single-stage en-bloc curved osteotomy surgical technique to reshape the prominent mandibular angle with a broad chin deformity with no increased in surgical risks but a high satisfaction rate and stable outcomes.

Dual Plane Augmentation Genioplasty Using Gore-Tex Chin Implants.

BackgroundThe chin shape and position is important in determining the general shape of the face, and augmentation genioplasty is performed alone or in combination with other aesthetic procedures. However, augmentation genioplasty using osteotomy is an invasive and complex procedure with the potential to damage mentalis muscle and mental nerve, to affect chin growth, and prolonged recovery. Our aim was to present our experience with a modified augmentation genioplasty procedure for hypoplastic chins using a Gore-Tex implant.MethodsTwo vertical slit incisions were made at the canine level to create a supraperiosteal pocket between the incisions, preserving the periosteum and mentalis muscle. Minimal sub-periosteal dissection was performed lateral to the incisions along the mandibular border. The both wings of implant were inserted under the periosteum to achieve a stable dual plane implantation.ResultsIn total, 47 patients underwent dual plane chin augmentation using a Gore-Tex implant between January 2008 and May 2013. The mean age at operation was 25.77 years (range, 15-55 years). There were 3 cases of infection; one patient was treated with antibiotics, the others underwent implant removal. Additionally, two patients complained of postoperative parasthesia that spontaneously improved without any additional treatment. Most patients were satisfied with the postoperative outcomes, and no chin growth problems were observed among the younger patients.ConclusionDual plane Gore-Tex chin augmentation is a minimally-invasive operation that is simple and safe. All implants yielded satisfactory results with no significant complications such as mental nerve injury, lower lip incompetence, or chin growth limitation.

Temporal mismatch between pain behaviour, skin Nerve Growth Factor and intra-epidermal nerve fibre density in trigeminal neuropathic pain

BackgroundThe neurotrophin Nerve Growth factor (NGF) is known to influence the phenotype of mature nociceptors, for example by altering synthesis of neuropeptides, and changes in NGF levels have been implicated in the pathophysiology of chronic pain conditions such as neuropathic pain. We have tested the hypothesis that after partial nerve injury, NGF accumulates within the skin and causes ‘pro-nociceptive’ phenotypic changes in the remaining population of sensory nerve fibres, which could underpin the development of neuropathic pain.ResultsEleven days after chronic constriction injury of the rat mental nerve the intra-epidermal nerve fibre density of the chin skin from had reduced from 11.6 ± 4.9 fibres/mm to 1.0 ± 0.4 fibres/mm; this slowly recovered to 2.4 ± 2.0 fibres/mm on day 14 and 4.0 ± 0.8 fibres/mm on day 21. Cold hyperalgesia in the ipsilateral lower lip was detectable 11 days after chronic constriction injury, although at this time skin [NGF] did not differ between sides. At 14 days post-injury, there was a significantly greater [NGF] ipsilaterally compared to contralaterally (ipsilateral = 111 ± 23 pg/mg, contralateral = 69 ± 13 pg/mg), but there was no behavioural evidence of neuropathic pain at this time-point. By 21 days post-injury, skin [NGF] was elevated bilaterally and there was a significant increase in the proportion of TrkA-positive (the high-affinity NGF receptor) intra-epidermal nerve fibres that were immunolabelled for the neuropeptide Calcitonin Gene-related peptide.ConclusionsThe temporal mismatch in behaviour, skin [NGF] and phenotypic changes in sensory nerve fibres indicate that increased [NGF] does not cause hyperalgesia after partial mental nerve injury, although it may contribute to the altered neurochemistry of cutaneous nerve fibres.