Rapid Evolution of a Squamous Cell Carcinoma In Situ to Locally Invasive With Perineural Involvement.

We present a case of rapidly progressing squamous cell carcinoma in situ (SCCis) with progression to aggressive SCC. An elderly gentleman with multiple medical comorbidities presented with a left zygomatic tumor initially diagnosed as SCCis with adnexal extension on histology. After a period of approximately 10 weeks, the patient underwent Mohs micrographic surgery (MMS) with evidence that the tumor was now consistent with a well-differentiated SCC, with perineural involvement. MMS was stopped after two stages and the patient was sent to head and neck surgical oncology for further evaluation and management. It has been reported in the literature that 3–5% of SCCis will progress to invasive SCC; although the inciting event to cause such progression is unknown, it is thought that mutations in key oncogenes or tumor suppressor genes such as TP53 may play a role. In addition, as many as 31% of SCCis may have a component of invasive SCC that is missed on initial histology due to sampling bias. This case reminds us that sampling bias can occur during biopsy, SCCis can rarely progress to invasive SCC, and highly aggressive SCCs may prove to be therapeutically challenging requiring a multidisciplinary approach. J Drugs Dermatol. 2020;19(11):1110-1111. doi:10.36849/JDD.2020.5184.

Relação anatômica da Bola de Bichat com ramos terminais do nervo facial / Anatomical Correlation among Bichat's fat pad with the Facial Nerve Terminal Branches

Introdução: A cirurgia de Bichectomia está sendo muito procurada por pessoas que visam diminuir o volume facial. O corpo adiposo da bochecha, ou bola de Bichat, possui uma complexa relação anatômica com estruturas faciais. Uma das complicações que o procedimento pode causar é a paralisia facial temporária ou permanente, em decorrência de injúrias causadas aos ramos terminais do nervo facial, devido à proximidade dessas duas estruturas anatômicas. Metodologia: O objetivo do presente artigo é enfatizar a relação anatômica da bola de Bichat com alguns ramos terminais do nervo facial através da dissecação de cadáveres. Foram feitas dissecações em três hemifaces de cadáveres humanos para a exposição do corpo adiposo da bochecha e dos ramos extracranianos do nervo facial. Resultados: A anatomia dos ramos terminais zigomáticos e bucais do nervo facial se mostrou variável em cada hemiface dissecada, mas sempre intimamente relacionados a bola de Bichat. Conclusões: O profissional que realiza a Bichectomia deve ter pleno conhecimento não só da técnica cirúrgica, mas também da variabilidade anatômica da região... (AU)

Introduction: The Buccal Fat Extraction surgery has been sought by people who aim to reduce facial volume. The Buccal fat pad has a complex anatomical correlation among the facial structures. The facial nerve paralysis is one of Bichat's fat extraction complications which might be temporary or permanent, due to the proximity of those anatomical structures. Methodology: The present article aims to emphasize the anatomical correlation between the Buccal fat pad and a few terminal branches of the facial nerve through the human cadaveric dissection. The dissection was performed on three human cadaveric hemifacial to expose the buccal fat pad body and the facial nerve extracranial branches. Results: The zygomatic and buccal terminal branches anatomy of the facial nerve has shown variables in each dissected hemifacial part. However, it has always presented closely related to Bichat's fat pad. Conclusions: The professional that performs the Buccal Fat Removal surgery must have to have the full knowledge not only about the surgical technique but the anatomical variability of the region, as well... (AU)

Clinical significance of buccal branches of the facial nerve and their relationship with the emergence of Stensen's duct: An anatomical study on adult Taiwanese cadavers.

OBJECTIVE: This observational study on adult Taiwanese cadavers focused mainly on the intersection of buccal branches of the facial nerve with Stensen's duct, using the emergence of Stensen's duct as the reference landmark. MATERIALS AND METHODS: Thirty-five cadaveric hemifaces were included in our research. Samples with facial defects due to tumor, trauma, or surgery were all excluded. Buccal branches of the facial nerve were identified according to the Gray's Anatomy 40th edition definition. The distance was measured from the intersection to the emergence of Stensen's duct, running from the anterior border of the parotid gland. RESULTS: In the 35 hemifaces, the number of buccal branch/Stensen's duct intersections ranged from 1 to 5 (average 2.49 ± 1.15). Two-point intersections accounted for 37% (13 hemifaces) of the sample, forming the largest group. Samples of facial nerve buccal branches were divided into four types: Type 1, with two buccal branches, accounted for 37.15% (13/35); Type 2, with three buccal branches, made up 48.59% (17/35) of our samples - the biggest group (Type 2-a was the most frequent pattern among our samples, with two superior buccal branches and one inferior buccal branch, accounting for 34.31% of our samples); Type 3, with four buccal branches, accounted for only 5.7%. Three cases of double Stensen's duct were classified as Type 4, though this is supposed to be a very rare anatomical variation. With Type 2a, the most frequent pattern among our specimens, the distance from the emergence of the Stensen's duct to the emergence point of the first superior buccal branch along the anterior border of the parotid gland was 9.58 ± 5.68 mm. The distance from the emergence point to the emergence of the inferior buccal branch along the anterior border of the parotid gland was 11.03 ± 5.38 mm. The distance (D1) from Stensen's duct to the emergence of the first superiorly located buccal branch of the group Type 2-a was statistically different from the distance (D1) of the other groups (p = 0.02). No direct anastomoses or communicating fibers between upper and lower buccal branches were noted in 11 hemifaces (31%). CONCLUSION: The distribution of buccal branches was described using the emergence of Stensen's duct as a reference landmark. According to our observations, the relationship between the buccal branches and Stensen's duct was much more complicated than described in previous studies. This was the first study to investigate the complete distribution of buccal branches of the facial nerve emerging from the anterior of the parotid gland, and their relative locations and branching numbers.

Neural network model of an amphibian ventilatory central pattern generator.

The neuronal multiunit model presented here is a formal model of the central pattern generator (CPG) of the amphibian ventilatory neural network, inspired by experimental data from Pelophylax ridibundus. The kernel of the CPG consists of three pacemakers and two follower neurons (buccal and lung respectively). This kernel is connected to a chain of excitatory and inhibitory neurons organized in loops. Simulations are performed with Izhikevich-type neurons. When driven by the buccal follower, the excitatory neurons transmit and reorganize the follower activity pattern along the chain, and when driven by the lung follower, the excitatory and inhibitory neurons of the chain fire in synchrony. The additive effects of synaptic inputs from the pacemakers on the buccal follower account for (1) the low frequency buccal rhythm, (2) the intra-burst high frequency oscillations, and (3) the episodic lung activity. Chemosensitivity to acidosis is implemented by an increase in the firing frequency of one of the pacemakers. This frequency increase leads to both a decrease in the buccal burst frequency and an increase in the lung episode frequency. The rhythmogenic properties of the model are robust against synaptic noise and pacemaker jitter. To validate the rhythm and pattern genesis of this formal CPG, neurograms were built from simulated motoneuron activity, and compared with experimental neurograms. The basic principles of our model account for several experimental observations, and we suggest that these principles may be generic for amphibian ventilation.

Anatomical study of the zygomatic and buccal branches of the facial nerve: Application to facial reanimation procedures.

The facial nerve is responsible for any facial expression channeling human emotions. Facial paralysis causes asymmetry, lagophthalmus, oral incontinence, and social limitations. Facial dynamics may be re-established with cross-face-nerve-grafts (CFNG). Our aim was to reappraise the zygomaticobuccal branch system relevant for facial reanimation surgery with respect to anastomoses and crossings. Dissection was performed on 106 facial halves of 53 fresh frozen cadavers. Study endpoints were quantity and relative thickness of branches, correlation to "Zuker's point", interconnection patterns and crossings. Level I and level II branches were classified as relevant for CFNG. Anastomoses and fusion patterns were assessed in both levels. The zygomatic branch showed 2.98 ± 0.86 (range 2-5) twigs at level II and the buccal branch 3.45 ± 0.96 (range 2-5), respectively. In the zygomatic system a single dominant branch was present in 50%, two co-dominant branches in 9% and three in 1%. In 66% of cases a single dominant buccal twig, two co-dominant in 12.6%, and three in 1% of cases were detected. The most inferior zygomatic branch was the most dominant branch (P = 0.003). Using Zuker's point, a facial nerve branch was found within 5 mm in all facial halves. Fusions were detected in 80% of specimens. Two different types of fusion patterns could be identified. Undercrossing of branches was found in 24% at levels I and II. Our study describes facial nerve branch systems relevant for facial reanimation surgery in a three-dimensional relationship of branches to each other. Clin. Anat. 32:480-488, 2019. © 2019 Wiley Periodicals, Inc.

Respiratory motoneuron properties during the transition from gill to lung breathing in the American bullfrog.

Amphibian respiratory development involves a dramatic metamorphic transition from gill to lung breathing and coordination of distinct motor outputs. To determine whether the emergence of adult respiratory motor patterns was associated with similarly dramatic changes in motoneuron (MN) properties, we characterized the intrinsic electrical properties of American bullfrog trigeminal MNs innervating respiratory muscles comprising the buccal pump. In premetamorphic tadpoles (TK stages IX-XVIII) and adult frogs, morphometric analyses and whole cell recordings were performed in trigeminal MNs identified by fluorescent retrograde labeling. Based on the amplitude of the depolarizing sag induced by hyperpolarizing voltage steps, two MN subtypes (I and II) were identified in tadpoles and adults. Compared with type II MNs, type I MNs had larger sag amplitudes (suggesting a larger hyperpolarization-activated inward current), greater input resistance, lower rheobase, hyperpolarized action potential threshold, steeper frequency-current relationships, and fast firing rates and received fewer excitatory postsynaptic currents. Postmetamorphosis, type I MNs exhibited similar sag, enhanced postinhibitory rebound, and increased action potential amplitude with a smaller-magnitude fast afterhyperpolarization. Compared with tadpoles, type II MNs from frogs received higher-frequency, larger-amplitude excitatory postsynaptic currents. Input resistance decreased and rheobase increased postmetamorphosis in all MNs, concurrent with increased soma area and hyperpolarized action potential threshold. We suggest that type I MNs are likely recruited in response to smaller, buccal-related synaptic inputs as well as larger lung-related inputs, whereas type II MNs are likely recruited in response to stronger synaptic inputs associated with larger buccal breaths, lung breaths, or nonrespiratory behaviors involving powerful muscle contractions.

Cheek Numbness Caused by Perineural Tumor Invasion of the Infraorbital Nerve: A Review of 3 Diagnostically Challenging Cases.

BACKGROUND Facial pain and numbness are common symptoms with a variety of causes; rarely, it is an initial sign of perineural infiltration of malignant tumors. CASE REPORT Here, we report 3 challenging cases, all presenting with pain and numbness of the cheek as the primary symptoms. Upon referral, there were neither signs of severe illness nor information about previous malignant diseases, while the diagnostic work-ups revealed additional involvement of the facial nerve in 2 of the cases. Surgical removal of the perineural tissue around the infraorbital nerve revealed perineural invasion by a squamous carcinoma. A more thorough review of their medical histories revealed that all 3 of the patients had had previous facial skin cancer. CONCLUSIONS Numbness or pain in the cheek may represent perineural invasion of a facial cutaneous carcinoma. This review of 3 cases addresses the necessity of identifying previous incidences of skin cancer in the medical history.

Searching for proprioceptors in human facial muscles.

The human craniofacial muscles innervated by the facial nerve typically lack muscle spindles. However these muscles have proprioception that participates in the coordination of facial movements. A functional substitution of facial proprioceptors by cutaneous mechanoreceptors has been proposed but at present this alternative has not been demonstrated. Here we have investigated whether other kinds of sensory structures are present in two human facial muscles (zygomatic major and buccal). Human checks were removed from Spanish cadavers, and processed for immunohistochemical detection of nerve fibers (neurofilament proteins and S100 protein) and two putative mechanoproteins (acid-sensing ion channel 2 and transient receptor potential vanilloid 4) associated with mechanosensing. Nerves of different calibers were found in the connective septa and within the muscle itself. In all the muscles analysed, capsular corpuscle-like structures resembling elongated or round Ruffini-like corpuscles were observed. Moreover the axon profiles within these structures displayed immunoreactivity for both putative mechanoproteins. The present results demonstrate the presence of sensory structures in facial muscles that can substitute for typical muscle spindles as the source of facial proprioception.

High variability of facial muscle innervation by facial nerve branches: A prospective electrostimulation study.

OBJECTIVES/HYPOTHESIS: To examine by intraoperative electric stimulation which peripheral facial nerve (FN) branches are functionally connected to which facial muscle functions. STUDY DESIGN: Single-center prospective clinical study. METHODS: Seven patients whose peripheral FN branching was exposed during parotidectomy under FN monitoring received a systematic electrostimulation of each branch starting with 0.1 mA and stepwise increase to 2 mA with a frequency of 3 Hz. The electrostimulation and the facial and neck movements were video recorded simultaneously and evaluated independently by two investigators. RESULTS: A uniform functional allocation of specific peripheral FN branches to a specific mimic movement was not possible. Stimulation of the whole spectrum of branches of the temporofacial division could lead to eye closure (orbicularis oculi muscle function). Stimulation of the spectrum of nerve branches of the cervicofacial division could lead to reactions in the midface (nasal and zygomatic muscles) as well as around the mouth (orbicularis oris and depressor anguli oris muscle function). Frontal and eye region were exclusively supplied by the temporofacial division. The region of the mouth and the neck was exclusively supplied by the cervicofacial division. Nose and zygomatic region were mainly supplied by the temporofacial division, but some patients had also nerve branches of the cervicofacial division functionally supplying the nasal and zygomatic region. CONCLUSIONS: FN branches distal to temporofacial and cervicofacial division are not necessarily covered by common facial nerve monitoring. Future bionic devices will need a patient-specific evaluation to stimulate the correct peripheral nerve branches to trigger distinct muscle functions. LEVEL OF EVIDENCE: 4 Laryngoscope, 127:1288-1295, 2017.

Effects of scratching and other counterstimuli on responses of trigeminothalamic tract neurons to itch-inducing stimuli in rats.

Counterstimuli such as scratching, pinching, noxious heat and cold, and innocuous cooling and warming have been shown to inhibit itch in humans. In the present study, the effects of each of these counterstimuli were determined on baseline firing rates and on sustained pruriceptive responses of rat trigeminothalamic tract neurons. We found that scratching had little, if any, effect on baseline firing levels but greatly reduced mean pruriceptive firing following scratching for nearly 1 min. None of the other noxious or innocuous counterstimuli significantly inhibited pruriceptive responses. Our results indicate that scratching, but not other counterstimuli, significantly reduces itch-induced responses of trigeminothalamic tract neurons.

A Cadaveric Study of the Communication Patterns Between the Buccal Trunks of the Facial Nerve and the Infraorbital Nerve in the Midface.

Most nerve communications reported in the literature were found between the terminal branches. This study aimed to clarify and classify patterns of proximal communications between the buccal branches (BN) of the facial nerve and the infraorbital nerve (ION).The superficial musculoaponeurotic system protects any communication sites from conventional dissections. Based on this limitation, the soft tissues of each face were peeled off the facial skull and the facial turn-down flap specimens were dissected from the periosteal view. Dissection was performed in 40 hemifaces to classify the communications in the sublevator space. Communication site was measured from the ala of nose.A double communication was the most common type found in 62.5% of hemifaces. Triple and single communications existed in 25% and 10% of 40 hemiface specimens, respectively. One hemiface had no communication. The most common type of communication occurred between the lower trunk of the BN of the facial nerve and the lateral labial (fourth) branch of the ION (70% in 40 hemifaces). Communication site was deep to the levator labii superioris muscle at 16.2 mm from the nasal ala. Communications between the motor and the sensory nerves in the midface may be important to increase nerve endurance and to compensate functional loss from injury.Proximal communications between the main trunks of the facial nerve and the ION in the midface exist in every face. This implies some specific functions in normal individuals. Awareness of these nerves is essential in surgical procedure in the midface.

Benign pleomorphic adenoma of minor salivary gland showing perineural invasion: a rare entity.

Perineural invasion is a rare and sporadically reported histological finding in relation to benign lesions. We present a case of a benign pleomorphic adenoma of a minor salivary gland of the cheek, exhibiting perineural involvement. There have been no previously reported cases of minor salivary gland pleomorphic adenomas exhibiting this phenomenon. This is also the first report of this rare feature in surgical literature pertaining to the head and neck region.

Reconstruction for facial nerve defects of zygomatic or marginal mandibular branches using upper buccal or cervical branches.

BACKGROUND: Many reconstructive methods for facial nerve defects have been described previously, such as the greater auricular nerve graft, the sural nerve graft, or hypoglossal-facial nerve anastomosis. Herein, we want to instruct a new technique of repairing facial nerve defects of zygomatic or marginal mandibular branches using upper buccal or cervical branches when we have to face segment defects of facial nerve with wide gaps between facial nerve stumps. METHODS: The distal part of the upper buccal or cervical branches with peripheral tissue was removed to repair the defects of zygomatic or marginal mandibular branches. Clinical and electromyographic examinations were employed to investigate the clinical efficacy of this method. RESULTS: Killed branches of facial nerve included 11 marginal mandibular branches and 16 zygomatic branches in 26 patients. The length of facial nerve defects ranged from 0.9 cm to 2.3 cm with a mean gap of 1.87 cm (SD, 0.89). Seventeen patients finally showed a superb facial function (grade I), 6 patients an excellent outcome (grade II), and 3 patients a good result (grade III). A fair or poor result (grade IV or V) was not observed. CONCLUSIONS: The essence of this method is equivalent to direct facial-facial nerve anastomosis which seems to be able to avoid synkinesis between the upper and lower face. We believe that this method is adaptable to the length of facial nerve defects less than 2 cm.

Complementary interactions between command-like interneurons that function to activate and specify motor programs.

Motor activity is often initiated by a population of command-like interneurons. Command-like interneurons that reliably drive programs have received the most attention, so little is known about how less reliable command-like interneurons may contribute to program generation. We study two electrically coupled interneurons, cerebral-buccal interneuron-2 (CBI-2) and CBI-11, which activate feeding motor programs in the mollusk Aplysia californica. Earlier work indicated that, in rested preparations, CBI-2, a powerful activator of programs, can trigger ingestive and egestive programs. CBI-2 reliably generated ingestive patterns only when it was repeatedly stimulated. The ability of CBI-2 to trigger motor activity has been attributed to the two program-promoting peptides it contains, FCAP and CP2. Here, we show that CBI-11 differs from CBI-2 in that it contains FCAP but not CP2. Furthermore, it is weak in its ability to drive programs. On its own, CBI-11 is therefore less effective as a program activator. When it is successful, however, CBI-11 is an effective specifier of motor activity; that is, it drives mostly ingestive programs. Importantly, we found that CBI-2 and CBI-11 complement each other's actions. First, prestimulation of CBI-2 enhanced the ability of CBI-11 to drive programs. This effect appears to be partly mediated by CP2. Second, coactivation of CBI-11 with CBI-2 makes CBI-2 programs immediately ingestive. This effect may be mediated by specific actions that CBI-11 exerts on pattern-generating interneurons. Therefore, different classes of command-like neurons in a motor network may make distinct, but potentially complementary, contributions as either activators or specifiers of motor activity.

Rapid and accurate identification of cut ends of facial nerves using a nerve monitoring system during surgical exploration and anastomosis.

PURPOSE: Surgical exploration and end-to-end neurorrhaphy is the preferred management for traumatic facial nerve injury. Traditionally, finding the cut ends of facial nerves depends mainly on a surgeon's experience. In this study, a nerve monitoring system to help the surgeon quickly and accurately identify, confirm, and locate the cut ends of facial nerve branches was investigated. PATIENTS AND METHODS: Six patients with traumatic facial nerve injury were selected, and the nerve monitoring system was applied during the surgical process of facial nerve exploration and anastomosis. Operation time and surgical outcome were used to evaluate the effect of this method. RESULTS: The surgical procedures required 6 to 15 minutes (mean, 10 minutes) for detecting and dissecting each cut end of a facial nerve branch. All cut ends of injured facial nerve branches were found during surgery in all 6 patients, and no intraoperative complications were encountered. The postoperative function of the facial nerve, evaluated by clinical examination and diagnostic electroneurography, was satisfactory and symmetrical in all 6 patients at 3 months. CONCLUSION: Using a nerve monitoring system could effectively help surgeons achieve rapid and accurate identification of the cut ends of facial nerves during surgical facial nerve exploration for traumatic facial nerve injury.

Immunohistochemistry and ultrastructural characteristics of nerve endings in the oral mucosa of rat.

The sensory nerve endings of the rat tongue, cheek and palate were studied using immunohistochemical staining and transmission electron microscopy analysis. The specimens were fixed in modified Karnovsky solution and embedded in Spurr resin. Substance P, calcitonin gene-related peptide (CGRP)- and protein gene product 9.5 (PGP b9.5)-containing nerve fibers in the rat tongue, cheek and palate were examined by electronic microscopical analysis and immunohistochemical localization. These fibers run very close to the basal lamina of the epithelium and extend into the filliform and fungiform papillae. Numerous plexiform fibers immunoreactive for substance P, CGRP and PGP 9.5 were found in the connective tissue of mucosa. Electron microscopic observations showed clearly immunostained nerve fibers, which are located very close to the basal lamina of epithelial cells. Some electron-dense granules may be observed in the axoplasms of both substance P and CGRP immunoreactive fibers. Several lamellar corpuscles into the subepithelial connective tissue papillae, Merkel corpuscles and numerous thin unmyelinated and myelinated axons were observed. The terminal axons revealed numerous mitochondria, neurofilaments, microtubules and clear vesicles in the base of axoplasmic protrusions. The lamellar cells showed caveolae and interlamelar spaces filled by amorphous substance. Between the lamellar cells and axoplasmic membrane, and in the adjacent lamellae region, desmosome-type junctions were observed. The quantitative and morphometric analysis showed nerve endings with an average area of 4.83 ± 3.4 µm(2) and 19.4 internal mitochondria in this site and the organized corpuscles with an average area of 79.24 ± 27.24 µm(2) and 24.23 internal mitochondria in this place. All the structures observed are involved in the transmission of pain and mechanoreceptors stimulus of these oral mucosae.

Sihler-stain study of buccal nerve distribution and its clinical implications.

OBJECTIVE: The aim of this study was to elucidate the precise distribution of the buccal nerve (BN) and its anatomic relationship with the infraorbital nerve (ION) and mental nerve (MN). STUDY DESIGN: Eight human specimens were subjected to Sihler staining, which is a highly accurate method for visualizing the distribution of nerve fibers without alteration of the nerve. RESULTS: It was found that the BN mainly proceeded medially from its point of entrance near the parotid duct opening to the angular area of mouth, giving off tiny branches along its trajectory. Some of these branches were distributed in upper angular area, over the cheilion, intermingling with branches of the ION. Intermingling of the BN and the MN was also observed in the premolar area of the lower lip. CONCLUSIONS: This new information regarding the distribution of BN should be taken into consideration when evaluating the possible effects of BN damage.

Neurosensory disturbances one year after bilateral sagittal split osteotomy of the mandibula performed with separators: a multi-centre prospective study.

Bilateral sagittal split osteotomy (BSSO) is an effective and commonly used treatment to correct mandibular hypo- and hyperplasia. Hypoesthesia of the inferior alveolar nerve (IAN) is a common complication of this surgical procedure. This prospective multi-centre study aimed to determine the incidence of neurosensory disturbances of the IAN after BSSO procedures performed without the use of chisels. Our study group comprised 158 patients, with a follow-up period of 1 year, who underwent BSSO (with or without Le Fort I) that incorporated the use of sagittal split separators and splitters but no chisels. The percentage of BSSO split procedures that resulted in IAN damage was 5.1%. The percentage of patients (without genioplasty) who experienced IAN damage was 8.9%. The concomitant genioplasty in combination with BSSO was significantly associated with hypoesthesia. Peri-operative removal of the wisdom tooth or a Le Fort I procedure did not influence post-operative hypoesthesia. We believe that the use of splitting forceps and elevators without chisels leads to a lower incidence of persistent post-operative hypoesthesia 1 year after BSSO of the mandible, without increasing the risk of a bad split.