A Comparison Between the Efficacy of Trigeminal Ganglion Radiofrequency Thermocoagulation and Ultrasound-Guided Maxillary-Mandibular Nerve Pulsed Radiofrequency in the Treatment of Trigeminal Neuralgia: A Randomized Clinical Trial.

Background and objective Trigeminal neuralgia (TN) is a debilitating disorder characterized by acute episodic attacks of pain that significantly impair patients' quality of life and overall functioning. Initial therapeutic strategies to treat this condition include pharmacological options, particularly carbamazepine. In cases with resistance to dose escalation and polypharmacy, interventional procedures may be warranted. The primary aim of this study was to compare the efficacy of trigeminal ganglion (TG) radiofrequency thermocoagulation (RFT) and ultrasound (US)-guided maxillary/mandibular (max/mand) nerve pulsed radiofrequency (PRF) for treating TN, based on the findings at six months post-treatment. The secondary aims were to assess the impact of these interventions on drug consumption and interventional safety based on adverse events. Methods This prospective, randomized, single-blind study was conducted at a single pain clinic. Forty-four patients were randomized into two groups. Group RFT received TG RFT at 60 °C, 65 °C, and 70 °C for 60 seconds each, whereas Group PRF received max/mand PRF for 240 seconds. Pain relief was assessed by using the numeric rating scale (NRS) and intervention effectiveness on medication consumption was evaluated by using the Medication Quantification Scale III (MQS III). The rates of intervention-related adverse events were also compared. Results Both RFT and PRF significantly alleviated pain at one and six months post-treatment compared to baseline (p<0.05). No statistical differences were found in the NRS and MQS III scores between the groups. At six months, 77.3% of RFT patients and 63.9% of PRF patients experienced at least 50% pain relief, with no statistically significant difference. Hypoesthesia occurred in two RFT patients, and masseter weakness was observed in one patient, while no adverse events were reported in the PRF group. Conclusions TG RFT and max/mand PRF are effective treatments for TN. US-guided max/mand PRF, which avoids RFT-associated complications and radiation exposure, may be the superior and preferable option. In this study, the potential space between the coronoid process and maxilla was used to access the maxillary nerve during the maxillary block and PRF procedures, in contrast to the classical approach through the mandibular notch. Further large-scale randomized controlled trials are required to gain deeper insights into the topic.

Assessment of traumatic mandibular nerve using MR neurography sequence: a preliminary study.

BACKGROUND: Iatrogenic mandibular nerve damage resulting from oral surgeries and dental procedures is painful and a formidable challenge for patients and oral surgeons alike, mainly because the absence of objective and quantitative methods for diagnosing nerve damage renders treatment and compensation ambiguous while often leading to medico-legal disputes. The aim of this study was to examine discriminating factors of traumatic mandibular nerve within a specific magnetic resonance imaging (MRI) protocol and to suggest tangible diagnostic criteria for peripheral trigeminal nerve injury. METHODS: Twenty-six patients with ipsilateral mandibular nerve trauma underwent T2 Flex water, 3D short tau inversion recovery (STIR), and diffusion-weighted imaging (DWI) acquired by periodically rotating overlapping parallel lines with enhanced reconstruction (PROPELLER) pulse sequences; 26 injured nerves were thus compared with contra-lateral healthy nerves at anatomically corresponding sites. T2 Flex apparent signal to noise ratio (FSNR), T2 Flex apparent nerve-muscle contrast to noise ratio (FNMCNR) 3D STIR apparent signal to noise ratio (SSNR), 3D STIR apparent nerve-muscle contrast to noise ratio (SNMCNR), apparent diffusion coefficient (ADC) and area of cross-sectional nerve (Area) were evaluated. RESULTS: Mixed model analysis revealed FSNR and FNMCNR to be the dual discriminators for traumatized mandibular nerve (p < 0.05). Diagnostic performance of both parameters was also determined with area under the receiver operating characteristic curve (AUC for FSNR = 0.712; 95% confidence interval [CI]: 0.5660, 0.8571 / AUC for FNMCNR = 0.7056; 95% confidence interval [CI]: 1.011, 1.112). CONCLUSIONS: An increase in FSNR and FNMCNR within our MRI sequence seems to be accurate indicators of the presence of traumatic nerve. This prospective study may serve as a foundation for sophisticated model diagnosing trigeminal nerve trauma within large patient cohorts.

Effectiveness and Distribution of Anesthesia for a Modified Extra Oral Maxillo-Mandibular Nerve Block for Dento-Alveolar Procedures: A Prospective Cohort Study.

Aim: To evaluate the effectiveness of a modified maxillo-mandibular nerve block technique that includes anesthetizing the maxillary and mandibular nerve with single injection. Materials and Methods: A prospective, clinical cohort study was carried out including patients who presented for surgical removal of maxillary and mandibular third molars. All patients were administered maxilla-mandibular nerve block through a single injection on one side. Three clinical neurosensory tests were used for mapping the area of anesthesia and to assess and grade objectively the effect of the block. Light touch (LT), two-point discrimination (TPD), pin prick (PP) and Electric pulp testing (EPT) were used for all branches of maxillary and mandibular nerve. An extra oral mapping chart for depth of anesthesia was maintained for each patient to categorize the grades as nil, intermediate and highly anesthetized areas. Results: 62 patients were assessed in the study. EPT showed greater depth of pulpal anesthesia in posterior teeth than the anterior in both maxilla and mandible. PP and TPD tests also showed that the anesthetic effect varied between posterior divisions demonstrating extreme anesthesia compared to the anterior divisions. Conclusion: This technique was found to be successful for surgical extractions involving the maxillary and mandibular regions. Supplementary Information: The online version contains supplementary material available at 10.1007/s12663-022-01755-w.

The anterior loop of the inferior alveolar nerve within the mentonian foramen: a scoping review.

PURPOSE: The aim of this study is to delineate the safety zone concerning the anteriorization of the AL and correlate it with the behavior of the AL, analyzing its feasibility. METHODS: Adhering to the Joanna Briggs Institute (JBI) manual guidelines, both the protocol and this review were conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) checklist. MeSH terms, combined with free terms, were utilized to search for articles in the following databases: Embase, LILACS, LIVIVO, PubMed/MEDLINE, Scopus, Web of Science, and grey literature. RESULTS: Fifteen articles were select following the eligibility criteria. An average safe zone of 4.75 mm in humans was observed, with a prevalence 60.8% and average anterior length of the AL of 2.09 mm in humans. CONCLUSION: The AL has varied patterns across different populations, then, it could not be asserted a 100% safe zone. Preoperative analysis of the AL with CBCT is always necessary. While it could be stated that a safe zone should be employed as an inviolable region, stipulated measures of a safe zone should be regarded as an area of greater attention in preoperative planning.

The Pterygomandibular Space: A Volumetric Evaluation Using the Novel A-Silicone Injections Method.

Inferior alveolar nerve block (IANB) is one of the most common procedures in operative dentistry, and a deep understanding of the normal anatomical variation of the pterygomandibular space (PM) is essential for its safe and successful administration. This cadaveric anatomical study aimed to use A-silicone injections to evaluate the volume of the PM. This study was conducted using 46 human cadaver heads (25 males and 21 females). A craniometric analysis was performed using the cadavers' ages, the number of silicone cartridges (carpules) used to fill the pterygomandibular space, Izard's Facial Index (FI), and the Cranial Index (CI). A Halstead mandibular block was performed by injecting 1.7 mL A-silicone cartridges (as an equivalent to standard local aesthetic carpules volume) into the PM. The cured silicone was extracted from the dissected mandibles. The volume (length, width, and thickness) of the extracted silicone and the number of silicone cartridges used to fill the space were evaluated. The results showed that there are statistically significant positive correlations between the CI and the width of the right PM, as well as the width and length of the left PM. A statistically significant correlation was found between the width of the left PM and the age of the cadaveric heads; the higher the age, the thicker the space on both sides. The volume of the PM corresponded to 1.5 cartridges on average.

The Effect of Delayed Photobiomodulation Therapy on Inferior Alveolar Nerve Recovery After Third Molar Removal: A Triple-Blinded Randomized Clinical Trial.

Background: Third molar removal is the primary reason for inferior alveolar nerve (IAN) damage, with 2% causing persistent neurosensory deficits. This study aimed to investigate how delayed photobiomodulation therapy affects long-lasting neurosensory disturbances. Methods: This study was conducted on patients with neurosensory disturbances lasting longer than 6 months. Patients were randomly allocated to the study and control groups, with the study group receiving a low-power diode laser (continuous wavelength of 810 nm, power of 200 mW) on 16 points (30 sec at each) for 12 sessions (2 sessions/week), while the control group received a placebo treatment by switched-off laser probe. Visual analog scale (VAS; ranging from 1 to 5), static light touch, two-point discrimination, direction discrimination, pinprick, and thermal discrimination tests were performed on each visit up to 9 months post-therapy to evaluate the recovery status. Results: Each group comprised 18 participants. The mean time since injury was 8.26 ± 2.05 and 8.38 ± 1.98 months for the control and intervention groups, respectively (p = 0.81). There was a significant improvement in the intervention group on the static light touch (p = 0.041), two-point discrimination (p = 0.028), VAS (p = 0.031), and pinprick (p = 0.014) tests on the 11th session and subsequent visits and also on direction discrimination test on the 12th session (p = 0.044) and after that. There was no significant difference in the thermal discrimination tests between the two groups (p > 0.05). Conclusion: Photobiomodulation demonstrated potential benefits in resolving persistent neurosensory deficits of the IAN, with noticeable improvements typically observed after around 35 days of treatment initiation (10 sessions).

Coexistence of a retroesophageal right subclavian artery with a left maxillary artery medial to the mandibular nerve.

This case report describes the coexistence of a retroesophageal right subclavian artery and left maxillary artery which passed deep to the mandibular nerve. An 88-year-old woman died of acute heart failure, and the postmortem revealed that the right subclavian artery originated from the aortic arch as the last branch at the level of the fourth thoracic vertebra, then passed between the esophagus and the vertebral column. The artery then ascended right superiorly and passed behind the anterior scalene muscle. The right vertebral artery arose from the retroesophageal right subclavian artery and entered the transverse foramen of the sixth cervical vertebra. The left maxillary artery branched at the common trunk of the posterior deep temporal and the inferior alveolar arteries. The maxillary artery then turned anteromedially and branched to give the middle meningeal artery. The mandibular nerve gave off the buccal nerve, deep temporal nerve and a thick nerve just below the foramen ovale. The auriculotemporal nerve that branched from the thick nerve ran deep to the maxillary artery. The maxillary artery turned anteriorly, passing deep to the branches. The artery then split to give the buccal artery and the anterior deep temporal artery. In the pterygopalatine section, the maxillary artery branched off to form the common trunk of the infraorbital and sphenopalatine arteries and the posterior superior alveolar artery. It may be necessary to pay attention to the course of the maxillary artery and its relationship to the mandibular nerve branches, when a retroesophageal right subclavian artery is seen.

The Management of a Geriatric Patient Using Dabigatran Therapy on Dentigerous Cyst with Oral Bleeding.

Jaw cysts represent a great matter of interest in oral and maxillofacial surgery. Jaw cyst surgery is a common intervention in oral surgery but, in the case of a multidisciplinary patient, the oral surgeon needs to meet with other specialists. A cyst is an epithelium-lined sac containing fluid and/or semisolid material due to epithelial cell proliferation, degeneration, and liquefaction; the hypertonic solution withdraws liquids from the surrounding tissues, while internal pressure exerts an equal strength on the cyst walls. Dentigerous cysts are the second most common odontogenic cysts after radicular cysts, and commonly few or no symptoms are reported. However, the most common diagnosis for dentigerous cyst is represented by eruption of the affected tooth or accidental diagnosis. Commonly, dentigerous cysts may be related to impacted third molars; in the case of impacted third molars and a dentigerous cyst, the tooth should be removed along with the cyst in the same intervention. Mandibular dentigerous cysts are common in children and adults, while dentigerous cysts are a rare neoformation in elderly patients. Treatment usually involves removal of the entire cyst and the associated unerupted tooth. This intervention may be more difficult if the cyst is large, the third molar is in contact with the mandibular nerve, and/or the patient has a medical history that may represent a relative or absolute contraindication. We present the case of a rare symptomatic manifestation of dentigerous cyst in an elderly patient in treatment with dabigatran therapy; for the treatment of dentigerous cysts in the elderly, we suggest a multidisciplinary approach with the use of the histological examination and a careful follow-up.

An Unusual Case of Unilateral Marginal Mandibular Nerve Palsy Associated with Odontogenic Space Infection.

Odontogenic space infections are common in dental practice, characterized by localized abscess formation with potential to spread to adjacent anatomical spaces. Neurogenic involvement in odontogenic infections is primarily found to be associated with sensory nerve branches, however involvement of motor nerves in odontogenic space infection leading to facial asymmetry has not been widely reported. In this case report, the authors present an unusual finding of facial asymmetry due to isolated marginal mandibular nerve weakness in a patient with a submandibular space infection. Supplementary Information: The online version contains supplementary material available at 10.1007/s12663-023-02019-x.

The alveolar canals and foramina in the first edition of Terminologia Oroanatomica: a preview.

Anatomy was initially developed out of necessity to decrease surgery complications. Over time, anatomists and surgeons have sometimes used different terms for the same anatomical structures, thus resulting in numerous discrepancies in terminology between anatomy and surgery. To avoid any confusion or misunderstanding and to better elucidate the oral anatomy terms, the Federative International Programme for Anatomical Terminology (FIPAT) organized a group of specialists on oral anatomy, Terminologia Oroanatomica (ToA) working group, composed of dentists, anatomy researchers, anatomy educators, oral and maxillofacial surgeons, and oral and maxillofacial radiologists. Within the ToA working group, major anatomical structures in the mandible, such as the mandibular canal, were focused and discussed to determine the most appropriate term, i.e., inferior alveolar canal. Although yet to be approved by the International Federation of Associations of Anatomists (IFAA), this article will preview some changes suggested by the ToA.

Multislice computed tomography demonstrating mental nerve paresthesia caused by periapical infection: A case report.

Components derived from an infected lesion within the bone can spread through various passages in the mandible, particularly via the mental foramen. Radiologically, the spread of infection is typically nonspecific and challenging to characterize; however, multislice computed tomography (MSCT) can effectively detect pathological changes in soft tissues and the bone marrow space. This report describes the case of a 55-year-old woman who experienced mental nerve paresthesia due to a periapical infection of the right mandibular second premolar. MSCT imaging revealed increased attenuation around the periapical lesion extending into the mandibular canal and loss of the juxtamental foraminal fat pad. Following endodontic treatment of the tooth suspected to be the source of the infection, the patient's symptoms resolved, and the previous MSCT imaging findings were no longer present. Increased bone marrow attenuation and obliteration of the fat plane in the buccal aspect of the mental foramen may serve as radiologic indicators of inflammation spreading from the bone marrow space.

Dexamethasone and concentrated growth factors on peripheral nerve injury: A clinic-relevant animal study.

BACKGROUND: Mandibular nerve injury is a common clinical condition that affects clinicians' management and patients' quality of life. In the literature, there are various effective treatments available. The primary purpose of this study was to determine and compare the effects of dexamethasone and concentrated growth factor (CGF) on regeneration in patients with nerve trauma that mimics clinical situations. METHODS: In this study, 36 rats were divided into 3 groups: the control, dexamethasone and CGF groups. The inferior alveolar nerve was traumatized through the extraction socket after mandibular molar tooth extraction in each group. RESULTS: The data showed a decrease in the control (4.5-4), dexamethasone (3-2), and CGF (4-3) groups according to the histological injury severity score (HISS) results. Compared with those in the other groups, the number of degenerative axons and edematous areas observed via histological examination were significantly lower in the CGF groups. Similarly, compared with those in the control group, the nNOS and Neurofilament-H positivity in the dexamethasone group on the 30th day (2,2 to 1,1 respectively) was significantly lower. The positivity of all the primary antibodies in the 3rd and 30th day CGF groups was significant compared than that in the dexamethasone 30th day group. CONCLUSION: According to the results of the analysis of the immunohistopathological and HISS data, the CGF groups exhibited greater regeneration than did the dexamethasone groups.

The location of mandibular foramen relative to the occlusal plane: a study on anatolian dry mandible.

Purpose: The study aims to evaluate the location of mandibular foramen (MF) with respect to the occlusal plane (OP) and its location on the ramus using Anatolian dry mandibles. Materials and methods: A total of 115 dry mandibles with mandibular molars were analyzed. The distance between the MF and the OP was examined with a flat metal plate. Group A was above the OP; group L was at level, and group B was below the OP. The distances between the MF and anterior border (A-MF), sigmoid notch (U-MF), posterior border (P-MF), and lower border (L-MF) were measured. The symmetry between the two sides was examined. Pearson chi-square and Student's t-test were performed for statistical analysis. Results: According to the analysis, 50.23% of MF was located below the OP (p<0.05). The mean distances of Groups A and B were 3.45 and 4.78 mm, respectively. There was no difference between the left and right in groups (p>0.05). The distance A-MF was 14.71 mm. There was no statistical difference between the distances A-MF and P-MF or U-MF and L-MF. Conclusion: Half of the MF (50.23%) was located below the occlusal plane with a mean distance of 4.78 mm. It may be helpful to place the needle 3-4 mm above the OP and 1.5-2 mm back of the anterior border to obtain a successful inferior alveolar nerve block. The MF was located at the center of the medial surface of the ramus.

Preservation of the inferior alveolar vasculonervous bundle in mandibular resective therapies: systematic review and report of two cases

Background: Segmental surgical resection is a frequently indicated procedure to treat aggressive mandibular tumors. One of the most important complications derived from this technique is permanent paresthesia of the inferior alveolar nerve (IAN), which significantly affects the quality of life of patients who experience it. This could be avoided through maneuvers that preserve the IAN. The objective of this paper is to review the main techniques for IAN preservation and to present 2 cases with the technique used by the author. Material and Methods: A systematic review was performed according to the PRISMA guidelines, apropos of two clinical cases reported in this study. The MEDLINE/PubMed and Scopus databases were searched. Several variables were considered and are presented in detail in the form of tables and figures. In addition, 2 case reports with NAI preservation techniques are presented. Results: 13 articles were finally obtained for analysis. 127 patients were evaluated, reporting mandibular resections associated with various pathologies. Various surgical techniques were used, all with the same goal of maintaining the IAN. In most of the patients, the maintenance of sensitivity was achieved, which was verified with different methods. Conclusions: Preservation of the IAN in maxillofacial surgical procedures where surgical resection of the mandibular bone has been performed is an alternative that has demonstrated successful results in terms of reducing postoperative sequelae and is currently positioned as a necessary and feasible procedure. (AU)

Successful radiofrequency thermocoagulation of the mandibular nerve for intractable pain associated with medication-related osteonecrosis of the jaw: a case report.

BACKGROUND: Bisphosphonates may cause serious adverse events, including osteonecrosis of the jaw. This article describes a case of successful application of radiofrequency thermocoagulation for pain caused by osteonecrosis of the jaw. CASE PRESENTATION: An 86-year-old woman who had received alendronate sodium hydrate for osteoporosis was diagnosed with osteonecrosis of the right mandible after dental treatment. Despite repeated conservative and debridement treatments, the patient could not eat due to intractable pain; accordingly, her condition was debilitated. The patient was referred to our pain management clinic for radiofrequency thermocoagulation of the right mandibular nerve. Immediately after the procedure, her pain drastically improved and she could eat; moreover, the pain has not recurred for 3 years. CONCLUSION: Our findings demonstrate that minimally invasive radiofrequency thermocoagulation may have long-term effects in patients with chronic pain caused by osteonecrosis of the jaw that is refractory to conservative treatment.

A novel extraoral ultrasound-guided approach for mandibular nerve block in Rahmani sheep.

BACKGROUND: Regional anesthesia is the favored choice in ruminant animals compared to general anesthesia, primarily due to its high safety margin and reduced demand for cost-intensive equipment in addition to its field applicability. Ultrasound-guided nerve block has gained significant attention in the field of veterinary medicine. This study utilized twenty-seven sheep of the native Rahmani breed to both demonstrate and evaluate the effectiveness of the ultrasound guided inferior alveolar nerve block technique. METHODS: The research comprised three phases: Phase 1 involved an anatomical examination of mandibles and sheep heads to locate the mandibular foramen and delineate the mandibular nerve course. Phase 2 included ultrasound-guided injection of methylene blue dye at specific sites along the mandibular nerve in cadaveric sheep heads. In Phase 3, clinical implementation of ultrasound-guided inferior alveolar nerve blocks was conducted in 27 live sheep, assessing efficacy, onset, and duration. RESULTS: Vertical extraoral ultrasound-guided nerve block was achieved successfully in 25 sheep (98%). A preliminary cadaveric study showed good distribution of the injectate at the mandibular nerve site. The mean onset time was 138 ± 18 s, and the mean duration time was 54 ± 4.1 min. Prominent analgesia of the ipsilateral mandible, medial surface of the cheek, and lateral border of the tongue was observed. CONCLUSIONS: Ultrasound-guided mandibular nerve block holds promise as a technique for providing effective and safe anesthesia in sheep undergoing mandibular procedures.

Inferior alveolar nerve repositioning surgical techniques and outcomes - a systematic review.

Inferior alveolar nerve (IAN) lateralization (IANL) or transposition (IANT) are both techniques allowing for dental implant placement in posterior atrophic mandibles. The aim of this study was to systematically review the implant survival rate and the complications associated with IAN reposition techniques with simultaneous implant placement in atrophic posterior mandibles. This systematic review was conducted following PRISMA guidelines (Preferred Reporting Items for Systematic review and Meta-Analysis). The review was designed to answer the following PICO question: Is IAN repositioning (I) a safe and efficient technique (O) to treat patient looking for fixed dental rehabilitation of an atrophic posterior mandible (P). Thirty-three articles were reviewed, including a total of 899 patients, and approximately 950 IAN repositioning procedures. Dental implant survival rate ranged between 86.95% and 100% with a mean dental survival rate of 90.16%. Among the 269 patients who underwent IANT, there were 93% immediate neurosensory disturbance, and 15% persistent neurosensory disturbance. Among the 350 patients who underwent IANL, there were 93% immediate neurosensory disturbance, and 6% persistent neurosensory disturbance. IANT and IANL are reliable techniques allowing safe dental implant placement in atrophic posterior mandible with high patient satisfaction. IANL seems to cause less persistent neurosensory disturbances compared to IANT. The level of evidence is poor due to the high number of bias present in the included studies. IAN neurosensory disturbance assessment should be better homogenized in order to increase comparability.

Intraosseous schwannoma of the mandible: new case series, literature update, and proposal of a classification.

Intraosseous schwannoma of the mandible is rare, with diagnostic and therapeutic challenges. The aims of this study were to report new cases of intraosseous schwannoma of the mandible and to propose a clinical classification, providing suggestions for treatment methods. The cases of 13 patients treated at the authors' hospital and 86 cases reported previously in the literature were reviewed. The most common clinical feature was facial swelling (60/93). The rate of cortical thinning or expansion was 44.8% (43/96); widening of the inferior alveolar nerve canal on radiographs was observed in 15 patients.

The relationship between the auriculotemporal nerve and middle meningeal artery in a sample of the South African population.

BACKGROUND: The interaction between the auriculotemporal nerve and the middle meningeal artery within the infratemporal fossa is vital in the spread of perineural tumours. Knowledge of their morphological and morphometric variations is critical to surgeons approaching the infratemporal fossa. There is a paucity of literature on the relationship between the auriculotemporal nerve and middle meningeal artery in a South African population. Hence, the aim of this study was to document the morphology and morphometry of the auriculotemporal nerve and its relationship to the middle meningeal artery within a South African cohort. MATERIALS AND METHODS: The infratemporal fossae of 32 cadaveric specimens were dissected and the auriculotemporal nerves and middle meningeal arteries were analysed, together with their variations. RESULTS: Nine out of 32 specimens displayed one-root, 14/32 two-root, 7/32 three-root, and 2/32 four-root auriculotemporal nerves. Eighteen auriculotemporal nerves originated from the mandibular nerve, while the rest had at least one communication to the inferior alveolar nerve. The mean distance between the first and second roots of the auriculotemporal nerve was 4.69 mm. There were V-shaped formations found in 23 auriculotemporal nerves. However, the middle meningeal artery only passed through 13/23 V-shapes. The maxillary artery was of a deep course in relation to the lateral pterygoid muscle in 19/32 and superficial in 13/32 of the sample. There were 15 accessory middle meningeal arteries present in 14/32 specimens. The accessory middle meningeal arteries often arose from the middle meningeal artery (46.67%). CONCLUSIONS: The results of this study show a high possibility of variations of the auriculotemporal nerve and middle meningeal artery in the South African population. The variations and interactions should be considered during surgical procedures.

Preoperative assessment of depressor anguli oris to prevent myectomy failure: An anatomical study using high-resolution ultrasound.

BACKGROUND: Myectomies of the lower lip depressor muscles have unexplained high failure rates. This study aimed to examine the depressor anguli oris (DAO) muscle using high-resolution ultrasound to identify potential anatomical explanations for surgical failures and to determine the accuracy of utilizing preoperative ultrasound assessment to improve myectomies. METHODS: Anatomical features of DAO and the surrounding anatomy were examined in 38 hemifaces of human body donors using high-resolution ultrasound and dissection. RESULTS: The ultrasound and dissection measurements showed the DAO muscle width to be 16.2 ± 2.9 versus 14.5 ± 2.5 mm, respectively, and the location of the lateral muscle border 54.4 ± 5.7 versus 52.3 ± 5.4 mm lateral to the midline. In 60% of the cases, the facial artery was either completely covered by lateral DAO muscle fibers or was found to be in direct contact with the lateral border. Significant muscle fiber continuity was present between the DAO and surrounding muscles in 5% of cases, whereas continuity between the depressor labii inferioris and surrounding muscles was considerably more common and pronounced. CONCLUSIONS: High-resolution ultrasound can accurately reveal important preoperative anatomical information in myectomies. Two potential explanations for the surgical failures were discovered: an overlap of lateral DAO muscle fibers over the facial artery could lead to inadequate resections and continuity with the surrounding muscles might lead to muscle function takeover despite adequate resections. Both can be uncovered preoperatively by the surgeon through a brief, directed ultrasound examination, which may allow for modification of the surgical plan to reduce surgical failure.