A rare case of the auriculotemporal and inferior alveolar nerves communication.

This case study describes anatomical variations in the branching pattern of the posterior division of the trigeminal nerve and its clinical implications for dental and craniofacial surgery. The study presents two uncommon variations observed in an elderly male cadaver. A communicating branch connecting one of three roots of the auriculotemporal nerve and inferior alveolar nerve just before entering the mandibular foramen on the right side, and three communicating branches between the IAN and lingual nerve on the left side. The presence of such variations may complicate anesthesia associated with oral surgery procedures.

The sublingual branch of the lingual nerve: Anatomical study and suggestion for a new terminology.

The lingual nerve carries somatosensory fibers from the anterior two-thirds of tongue. The parasympathetic preganglionic fibers arising from the chorda tympani also travel with the lingual nerve in the infratemporal fossa to synapse in the submandibular ganglion to innervate the sublingual gland. However, only a few studies have investigated the specific nerve that innervates the sublingual gland and surrounding tissue i.e., the so-called sublingual nerve. Therefore, this study aimed to clarify the anatomy and definition of the sublingual nerves. Thirty sides from formalin fixed cadaveric hemiheads underwent microsurgical dissection of the sublingual nerves. The sublingual nerves were found on all sides and categorized into three branches, i.e., branches to the sublingual gland, branches to the mucosa of the floor of the mouth, and gingival branches. Additionally, branches to the sublingual gland were subcategorized into types I and II based on the origin of the sublingual nerve. We suggest that the lingual nerve branches should be categorized into five branches, i.e., branches to the isthmus of the fauces, sublingual nerves, lingual branches, posterior branch to the submandibular ganglion, and branches to the sublingual ganglion.

The complete anatomy of the lingual nerve: A meta-analysis with implications for oral and maxillofacial surgery.

Lingual nerve (LN) injury during surgical procedures in the third molar region warrants a detailed study of its common pathway and important variations. Therefore, the objective of this study was to analyze and compile the multiple anatomical variations of the LN for use in oral and maxillofacial surgery. It is anticipated that the results of the present meta-analysis may help to minimize the possible complications when performing procedures associated with this anatomical entity. Major online databases such as PubMed, Web of Science, Scopus, Embase were used to gather all relevant studies regarding the LN anatomy. The results were established based on a total of 1665 LNs. The pooled prevalence of the LN being located below the lingual/ alveolar crest was found to be 77.87% (95% CI: 0.00%-100.00%). The LN was located above the lingual/ alveolar crest in 8.21% (95% CI: 4.63%-12.89%) of examined nerves. The most common shape of the LN was established to be round with a prevalence of 40.96% (95% CI: 23.96%-59.06%), followed by oval at 37.98% (95% CI: 23.98%-53.02%) and flat at 25.16% (95% CI: 12.85%-39.77%). In conclusion, we believe that this is the most accurate and up-to-date study regarding the anatomy of the LN. The LN was found to be located below the lingual/alveolar crest in 77.87% of the cases. Furthermore, the LN was found to enter the tongue under the submandibular duct in 68.39% of the cases. Knowledge about the anatomy of the LN is crucial for numerous oral and maxillofacial procedures such as during the extraction of the third molar.

Mental and Lingual Nerve Paresthesia Following Infiltration Anesthesia for Dental Implant Placement in a Patient With Guillain-Barré Syndrome.

Guillain-Barré syndrome (GBS) is a rare rapid onset autoimmune peripheral polyneuropathy, most commonly characterized by inflammatory demyelination of peripheral nerves. Patients with GBS are considered higher risk for anesthetic-induced neurotoxicity caused by demyelination. In the present report, a case is described of a 56-year-old man with GBS who experienced mental and lingual nerve paresthesia following infiltration anesthesia for dental implant placement in the posterior mandible. The pareshesia lasted 5 months postoperatively and subsided spontaneously without any intervention. The patient was successfully restored with fixed partial dental prosthesis without any other complication. This is considered the first report of such complication in patient with GBS after local anesthesia in the oral and maxillofacial region. Possible pathogenic mechanism of the complication and clinical implications are discussed.

Surgical anatomy of the lingual nerve for palate surgery: where is located and how to avoid it.

PURPOSE: To describe the anatomic relationship of the lingual nerve with the lateral oropharyngeal structures. METHODS: An anatomic dissection of the lateral oropharyngeal wall was conducted in eight sides from four fresh-frozen cadaveric heads. Small titanium clips were placed along the lingual nerve and the most anterior and medial border of the medial pterygoid muscle. Radiological reconstructions were employed for optimal visualization; the coronal view was preferred to resemble the surgical position. The distance between the lingual nerve and the medial pterygoid muscle at its upper and lower portion was measured radiologically. The trajectory angle of the lingual nerve with respect to the pterygomandibular raphe was obtained from the intersection between the vector generated between the clips connecting the upper and lower portion of the medial pterygoid muscle with the vector generated from the lingual nerve clips. RESULTS: The mean distance from the upper portion of the medial pterygoid muscle and superior lingual nerve clips was 10.16 ± 2.18 mm (mean ± standard deviation), and the lower area of the medial pterygoid muscle to the lingual nerve was separated 5.05 ± 1.49 mm. The trajectory angle of the lingual nerve concerning to the vector that describes the upper portion of the most anterior and medial border of the medial pterygoid muscle with its lower part was 43.73º ± 11.29. CONCLUSIONS: The lingual nerve runs lateral to the lateral oropharyngeal wall, from superiorly-inferiorly and laterally-medially, and it is closer to it at its lower third.

Preoperative visualization of the lingual nerve by 3D double-echo steady-state MRI in surgical third molar extraction treatment.

OBJECTIVES: To assess the lingual nerve (LN) visualization using a 3D double-echo steady-state MRI sequence (3D-DESS). MATERIALS AND METHODS: Three readers prospectively evaluated the LN for its continuous visibility in 3D-DESS MRI in 19 patients with an indication for removal of mandibular impacted third molars, using a 5-point scale (4 = excellent to 0 = none). Six LN anatomical intermediate points (IP) were selected and checked for their detectability by a 4-point scale (4 = yes to1 = no). Inter- and intra-rater agreement was evaluated using intraclass correlation coefficient and percentage of agreement. RESULTS: The average nerve continuity score was 3.3 ± 0.46. In 35% of the cases, the entire course was continuously visible. In 10%, the proximal and 60%, the distal part of the nerve was not continuously visible. Inter- and intra-reader agreement was good (ICC = 0.76, ICC = 0.75). The average detectability score of all IP was 3.7 ± 0.41. From IP1 to IP5, the detectability was excellent; meanwhile, IP6 had lower visibility. The inter- and intra-reader percentage of agreement was 77% and 87%. CONCLUSIONS: The 3D-DESS sequence allowed accurate and continuous visualization of the LN with high reproducibility in more than one-third of the patients. This could improve the preoperative clarification of the LN position and thereby reduce complications during dentoalveolar surgical interventions. CLINICAL RELEVANCE: 3D-DESS MRI might be beneficial in clinical scenarios where the second molar is elongated or presents a difficult rotational position while simultaneously having a close positional relationship to the third molar. Thereby, osteotomy performed more lingually, indicating extended lingual flap detachment may increase the risk of LN damage.

Anatomical Relationship Between the Lingual Nerve and Submandibular Duct.

ABSTRACT: The purpose of this study was to investigate the anatomical relationship between the lingual nerve and submandibular duct. This study included 1403 patients with submandibular or sublingual gland diseases who underwent intraoral removal of submandibular gland sialoliths, submandibular glands, or sublingual glands. Of all patients, 33 patients underwent bilateral surgeries. All surgeries were performed a single surgeon, and the anatomical relationship between the lingual nerve and submandibular duct was always identified intraoperatively and recorded in the operation recorded. The anatomical relationship was investigated based on the intraoperative findings. The lingual nerve which crosses above the submandibular duct was detected in 8 of 1436 sides (0.6%). There were 4 in the right sides and 4 in the left sides. The lingual nerve below the submandibular gland was seen in 99.4%. Although the lingual nerve crosses above the submandibular duct with a rarer incidence, surgeons should beware of injuring the lingual nerve during intraoral salivary gland surgery.

An Atypical Path of the Lingual Nerve in the Retromolar Region: Incidence in Oral Surgery.

The Lingual nerve is frequently anesthetized during oral, maxillofacial, or otorhinolaryngology surgery. It originates below the oval hole in the infratemporal region, follows its path down and forward, and moves away from the medial surface of the ramus. From there, it goes just above the mylohyoid line. It approaches the lateral margin of the tongue and crosses the Wharton's canal, and divides into numerous branches. Some cases of temporomandibular joint syndrome or myofascial pain syndrome could be a result of its anatomical variations. Also, the jurisprudence has always condemned the practitioner if for not demonstrating that the path of the injured nerve presents an anomaly which makes his involvement inevitable. The purpose is to present one of the multiple atypical paths of the lingual nerve not described in the retromandibular trigone, demonstrating that its damage constitutes a risk that cannot be controlled.

Outcomes of Direct Lingual Nerve Repair After an Injury: A Systematic Review.

PURPOSE: The purpose of this study was to conduct a systematic review with meta-analysis to investigate the outcomes of direct lingual nerve repair after injury. MATERIALS AND METHODS: The studies in this review were compiled by using PubMed/Medline and ScienceDirect, which were searched by a single reviewer (M.K.) from their inception until March 10, 2020. Two independent reviewers (M.K. and V.B.Z.) who were blinded to each other's assessments reviewed full-text articles to assess for study inclusion. Outcomes were dichotomized as either functional sensory recovery (FSR) or no FSR. Clinical testing must have been assessed at a minimum of 6 months postoperatively. FSR was defined as grade S3, S3+, or S4 on the British Medical Research Council scale of neurosensory function. Studies were only eligible if they provided the number of patients treated with conduits or time from injury to repair and the associated rates of FSR with each intervention. RESULTS: The initial search using the key terms yielded 4,921 results, which was then eventually filtered down to 6 articles after multiple levels of appraisal. Five articles were retrospective cohort studies and 1 was a randomized controlled study. Four of the 6 studies reported an FSR of grade S3 or higher in 85% or more of the patients. Conduit use was not associated with a significantly greater likelihood of achieving FSR (pooled risk ratio = 1.10; 95% confidence interval, 0.96 to 1.27; P = .17). Repair within 6 months was associated with significantly improved likelihood of achieving FSR (pooled risk ratio = 0.84; 95% confidence interval, 0.71 to 0.99; P = .04). CONCLUSIONS: The use of conduits during repair was not associated with clinically significant increased FSR. Early repair was associated with a beneficial effect on FSR; however, heterogeneity was an issue with the studies. There is a lack of strong evidence owing to the nature of studies analyzed and the need for further research is required.

Dual innervation of the submandibular gland by nerve to mylohyoid and chorda tympani.

The chorda tympani typically utilises the lingual nerve and submandibular ganglion to transmit parasympathetic fibres to the submandibular gland. During a routine anatomy dissection, the submandibular gland was found to be innervated by both the lingual nerve and the nerve to mylohyoid. The clinical implications of this variant dual innervation to the submandibular gland is not clear due to its rarity: however, recognising such a variation should be borne in mind during surgical intervention near the nerve to mylohyoid.

[Reconstruction of the lower alveolar nerve during mandible resection due to benign tumors]. / Rekonstruktsiya nizhneal'veolyarnogo nerva pri rezektsii nizhnei chelyusti po povodu dobrokachestvennykh opukholei.

OBJECTIVE: Development of a method for reconstruction of the inferior alveolar nerve and evaluation of its effectiveness in resection of the lower jaw for benign tumors. MATERIAL AND METHODS: In the period from 2018 to 2020, 10 resections were performed for benign odontogenic neoplasms (myxoma, ameloblastoma, osteoblastoclastoma) at the age of 18 to 60 years. Tactile, pain and temperature sensitivity were subjectively studied. The assessment of subjective sensitivity was carried out five times: before the operation, after 21 days, after 3.6 months and a year after the operation, an electromyograph «SYNAPSIS¼ was used for an objective assessment of sensitivity. The studies were conducted twice: 21 days after the operation and 12 months later. Reinervation was carried out by two methods. Method I: by transferring the insertion from the calf nerve and applying end-to-end neuroanastomoses between the proximal and distal ends of the inferior alveolar nerve (5 patients); method II: transferring the insertion from the calf nerve to the lingual nerve. Neuroanastomoses are applied periepineurally between the distal end of the inferior alveolar nerve and the lingual nerve «end to side¼ (5 patients). RESULTS: After 12 months, all types of sensitivity were restored in the control group in all patients, and in the second group in 80%. All patients had areas of hyposthesia in terms of temperature and tactile sensitivity. The results of trigeminal evoked potentials were negative in all patients 21 days after surgery, and peaks of evoked potentials were recorded in 9 (90%) patients 12 months later. CONCLUSION: These reconstruction techniques are effective both when the proximal end of the inferior alveolar nerve is preserved, and when it is impossible to preserve it. With minimal donor damage, the sensitivity of the lower lip is restored, which significantly improves the quality of life of patients and their social adaptation.

Appearance of normal MRI anatomy of the lingual nerve using steady-state free precession sequences at 3-T.

The aim of this study is to assess the value of SSFP MRI sequence in depicting the normal anatomy of the lingual nerve (LN), particularly in the molar region, in order to help the periodontists, dentists and oral surgeons in their daily practice. The study group included 24 patients who were to undergo MR study for a reason unrelated to our purpose. All imaging was performed by using a 3.0T system with a head and neck multiarray coil. The evaluation criteria included image quality factors such as the identification of the LN, its demarcation and its contrast to surrounding tissues on a five-point scale. The LN is clearly visible throughout its course from its origin from the mandibular nerve (MN) to the mylohyoid muscle. In edentulous patients, the LN could be damaged during surgical procedures especially it during the dissection and retraction of a lingual flap and, above all, during the suture due to a direct trauma caused by the needle or indirectly during tying the knot.

Ultrasonographic characterization of lingual structures pertinent to oral, periodontal, and implant surgery.

OBJECTIVES: Increased applications of ridge augmentation in the lingual posterior mandible call for an urgent need to study its anatomy. Therefore, our first aim was to validate ultrasound in measuring the mandibular lingual structures in human cadavers. Secondarily, to test its feasibility in imaging the lingual nerve in live humans. MATERIALS AND METHODS: Nine fresh un-embalmed fully/partially edentulous cadaver heads were utilized for aim 1. Three areas in the lingual mandible were imaged (mandibular premolar, molar, and retromolar). Immediately after, biopsies were harvested from each site. The thickness of the mucosa, mylohyoid muscle, and lingual nerve diameter was measured via ultrasound and statistically compared to histology. Similarly, the lingual nerve in live humans was also imaged. RESULTS: None of the differences between the ultrasound and histology measurements reached statistical significance (p > .05). The mean mucosal thickness via ultrasound and histology was 1.45 ± 0.49 and 1.39 ± 0.50 mm, 5 mm lingual to the mylohyoid muscle attachment. At 10 mm beyond the attachment, the ultrasound and histologic values were 1.54 ± 0.48 and 1.37 ± 0.49, respectively. The mean muscle thickness measured via ultrasound and histology was 2.31 ± 0.56 and 2.25 ± 0.47 mm, at the 5 mm distance. At the 10 mm distance, the measurements were 2.46 ± 0.56 and 2.36 ± 0.5 mm, respectively. The mean ultrasonic lingual nerve diameter was 2.38 ± 0.44 mm, versus 2.43 ± 0.42 mm, with histology. The lingual nerve diameter on 19 live humans averaged to 2.01 ± 0.35 mm (1.4-3.1 mm). CONCLUSIONS: Within its limitations, ultrasound accurately measured mandibular lingual soft tissue structures on cadavers, and the lingual nerve on live humans.

MRI of the inferior alveolar nerve and lingual nerve-anatomical variation and morphometric benchmark values of nerve diameters in healthy subjects.

OBJECTIVE: Since MRI using dedicated imaging sequences has recently shown promising results in direct visualization of the inferior alveolar nerve (IAN) and the lingual nerve (LN) with high spatial resolution, the aim of this study was to generate suitable standard specifications to reliably depict the IAN and LN in MRI and to delineate the anatomy and its variants of these nerves in healthy subjects. METHODS: Thirty healthy volunteers were examined on a 3-T scanner (Elition, Philips Healthcare, Best, the Netherlands). The sequence protocol consisted of 3D STIR, 3D DESS, and 3D T1 FFE "black bone" sequences. RESULTS: The study reconfirmed a good feasibility of direct visualization of proximal and peripheral portions of the IAN and of the proximal course of the LN. The STIR sequence showed the highest apparent signal to noise ratio (aSNR) and best apparent nerve-muscle contrast to noise ratio (aNMCNR) for IAN and for the LN. The applied MRI sequences allowed to differentiate the tissue composition of the neurovascular bundle inside the mandibular canal. CONCLUSION: Dedicated MRI sequence protocols proved effectively to detect the IAN and LN and their course in healthy volunteers. The tissue composition of the mandibular neurovascular bundle was conclusively distinguishable as was the varying topography inside multiple bony channels. CLINICAL RELEVANCE: The presented data on the precise and valid visualization of the IAN and LN have clinical implications in respect to local anesthesia prior to dental treatments in the mandible but also regarding surgical procedures and implant insertion in the molar region.

How to avoid iatrogenic lingual nerve injury in the retromolar area: an anatomical study of retromolar pad and lingual nerve.

PURPOSE: This study aimed to investigate the relationship between the retromolar gland and pad, and the relationship between the LN and retromolar gland/pad to establish a new landmark for avoiding LN injury. METHODS: Sixty-two lingual nerves from fresh-frozen cadavers were used for this study. The age of the specimens at the time of death ranged from 57 to 98 with a mean of 76.5 years. The mucous incision was made into the medial border of the retromolar pad and the submucosal tissue depth of the initial incision was bluntly dissected to expose the lingual nerve. When the LN was identified, the mucosa overlying the retromolar pad was removed to expose the retromolar gland to confirm if the retromolar pad corresponds to the retromolar gland. RESULTS: On all sides, the lingual nerve was found to course medial to the retromolar pad and inferior to the inferior border of the superior pharyngeal constrictor muscle to enter the sublingual space via the pterygomandibular space. The retromolar pad corresponded to the retromolar gland on all sides. This demonstrated that the retromolar pad is an overlying mucosa of the retromolar gland. No LN was found to travel through the retromolar gland. CONCLUSION: We suggest that the retromolar pad can be used as a new landmark for avoiding iatrogenic LN injury.

Plunging ranula with lingual nerve tether: Case report and literature review.

Plunging ranulas are most often treated surgically; various surgical approaches may be necessary depending on the unique characteristics of each case. Here, we present the case of a plunging ranula noted on imaging to have a cordlike tether, which was revealed intraoperatively to be the lingual nerve. This case illustrates the importance of preoperative imaging for surgical planning, and when a transcervical approach may be the best choice for plunging ranulas.

Anatomy of the lingual nerve: Application to oral surgery.

The purpose of this research is to obtain morphological information about the traveling route, branching pattern, and distribution within the tongue of the lingual nerve, all of which are important for oral surgical procedures. Using 20 sides from 10 Japanese cadaveric heads, we followed the lingual nerve from its merging point with the chorda tympani to its peripheral terminal in the tongue. We focused on the collateral branches in the area before reaching the tongue and the communication between the lingual and hypoglossal nerves reaching the tongue. The collateral branches of the lingual nerve were distributed in the oral mucosa between the palatoglossal arch and the mandibular molar region. Two to eight collateral branches arose from the main trunk of the nerve, and the configuration of branching was classified into three types. More distally, the lingual nerve started to communicate with the hypoglossal nerve before passing the anterior border of the hyoglossus muscle. Nerve communications were also found in the main body and near the apex of the tongue. A thorough understanding of the collateral branches near the tongue, and the communication with the hypoglossal nerve inside the tongue, will help to prevent functional disorders from local anesthesia and oral surgical procedures associated with the lingual nerve. Clin. Anat. 32:635-641, 2019. © 2019 Wiley Periodicals, Inc.

Defining the anatomy of the neonatal lingual frenulum.

The lingual frenulum is recognized as having the potential to limit tongue mobility, which may lead to difficulties with breastfeeding in some infants. There is extensive variation between individuals in the appearance of the lingual frenulum but an ambiguous relationship between frenulum appearance and functional limitation. An increasing number of infants are being diagnosed with ankyloglossia, with growing uncertainty regarding what can be considered "normal" lingual frenulum anatomy. In this study, microdissection of four fresh tissue premature infant cadavers shows that the lingual frenulum is a dynamic, layered structure formed by oral mucosa and the underlying floor of mouth fascia, which is mobilized into a midline fold with tongue elevation and/or retraction. Genioglossus is suspended from the floor of mouth fascia, and in some individuals can be drawn up into the fold of the frenulum. Branches of the lingual nerve are located superficially on the ventral surface of the tongue, immediately beneath the fascia, making them vulnerable to injury during frenotomy procedures. This research challenges the longstanding belief that the lingual frenulum is a midline structure formed by a submucosal "band" or "string" and confirms that the neonatal lingual frenulum structure replicates that recently described in the adult. This article provides an anatomical construct for understanding and describing variability in lingual frenulum morphology and lays the foundation for future research to assess the impact of specific anatomic variants of lingual frenulum morphology on tongue mobility. Clin. Anat. 32:824-835, 2019. © 2019 The Authors. Clinical Anatomy published by Wiley Periodicals, Inc. on behalf of American Association of Clinical Anatomists.

The lingual nerve: overview and new insights into anatomical variability based on fine dissection using human cadavers.

This article, for both researchers and clinicians, presents an overview of the lingual nerve and highlights how new insights into human anatomical variability can be gained by integrating fine dissection of cadavers with neuroanatomical approaches, microscopic studies, and morphometric techniques. Textbooks mainly provide descriptions of the typical or common gross anatomical appearance of structures in the human body with little reference to the nature and extent of variation that may be encountered within and between populations. Furthermore, few texts attempt to integrate descriptions of the regional distribution and branching of neural structures with their central connections or their microscopic anatomy. Using the lingual nerve as an example from the head and neck region, we show that there is still an important place for detailed fine dissections of human cadavers when they are also integrated with morphometric techniques applied to data representing observed variation at both macro- and micro-levels. It is essential that health professionals have a sound understanding of the nature and extent of anatomical variation displayed normally by their patients so that they can perform procedures, such as local anaesthesia and surgery, safely and also be able to correctly diagnose pathology when it is present.

Solitary neurofibroma of the floor of the mouth: rare localization at lingual nerve with intraoral excision.

BACKGROUND: Neurofibromas (NF) are benign tumors of the peripheral nerves that are composed of Schwann cells, perineural-like cells and fibroblasts. The differential diagnosis for a solitary intraneural variant of neurofibroma arising in the floor of the mouth is broad and includes a submandibular gland neoplasm and adenopathy, among others. The intraoral approach is the best choice for a medium-sized lesion. CASE PRESENTATION: We report a rare case of a solitary neurofibroma of the floor of the mouth in a 31-year-old male. The patient consulted the dental emergency department for acute pain of the left mandible. Systematic clinical examination revealed the presence of a mass in the left mouth floor. The panoramic x-ray was not conclusive and the magnetic resonance imaging (MRI) revealed a well-defined soft tissue lesion with homogenous isosignal intensity on the T1-weighted image, high intensity signal on the T2-weighted image and heterogeneous enhancement following contrast-enhancement on the T1-weighted Fast Sat image. The surgical excision of the soft-tissue neoplasm was accomplished by an intraoral approach. The specimen was sent for histopathologic analysis and Immunohistochemical studies which confirmed the diagnosis of a myxoid predominant intraneural solitary neurofibroma. CONCLUSION: The diagnosis of neurofibroma was confirmed by histopathological evaluation and immunohistochemical studies which also excluded other entities in the histopathologic differential diagnosis including schwannoma and a malignant peripheral nerve sheath tumor among other. Localized (solitary) neurofibromas most often occur as sporadic lesions, however; diagnosis of a solitary neurofibroma prompts clinical evaluation to exclude the remote possibility of neurofibromatosis. The purpose of this case report is to raise awareness of the uncommon presentation of neurofibroma and to document the successful management of such a lesion using an intraoral approach.