SnapShot: Orofacial Sensation.

Ophthalmic, maxillary, and mandibular branches of the trigeminal nerve provide sensory innervation to orofacial tissues. Trigeminal sensory neurons respond to a diverse array of sensory stimuli to generate distinct sensations, including thermosensation, mechanosensation, itching, and pain. These sensory neurons also detect the distinct sharpness or pungency of many foods and beverages. This SnapShot highlights the transduction ion channels critical to orofacial sensation.

[Efficacy of CT-guided partial radiofrequency ablation of bilateral responsible cranial nerves in the treatment of Meige syndrome].

Objective: To evaluate the efficacy of CT-guided partial radiofrequency ablation of bilateral responsible cranial nerves in the treatment of Meige syndrome. Methods: The Clinical data of 56 patients with Meige syndrome in the Department of Pain Medicine, Affiliated Hospital of Jiaxing University from June 2019 to January 2023 were retrospectively analyzed [19 males and 37 females, aged 42-76 (58.6±8.3) years], including 51 cases of blepharospasm, 3 cases of oromandibular dystonia and 2 cases of blepharospasm concomitant with oromandibular dystonia. CT-guided partial radiofrequency ablation of bilateral responsible cranial nerves was performed on different types of Meige syndrome. And the efficacy and complications of the technique were observed. Results: Fifty-one patients with blepharospasm Meige syndrome underwent CT-guided radiofrequency of facial nerve through bilateral stylomastoid foramen punctures, the symptoms of blepharospasm disappeared completely, leaving bilateral mild and moderate facial paralysis symptoms. Three patients with oral-mandibular dystonia underwent CT-guided radiofrequency therapy by bilateral foramen ovale puncture of mandibular branches of trigeminal nerve, masticatory muscle spasm disappeared, the patients had no difficulty opening the mouth, and the skin numbness in bilateral mandibular nerve innervation area was left. Two cases of Meige syndrome with blepharospasm concomitant with oromandibular dystonia were treated by radiofrequency of facial nerve and mandibular branch of trigeminal nerve, and all symptoms disappeared. The patients were followed up for 1-44 months after the operation, and the symptoms of mild and moderate facial paralysis disappeared at (3.2±0.8) months after the operation, but the numbness did not disappear. Three patients with blepharospasm recurred at the 14, 18 and 22 months after the operation, respectively, while the rest cases did not recur. Conclusions: According to different types of Meige syndrome, CT-guided partial radiofrequency ablation of responsible cranial nerves can effectively treat the corresponding type of Meige syndrome. The complications are only mild and moderate facial paralysis which can be recovered, and/or skin numbness in the mandibular region.

Genetic spectrum of Charcot-Marie-Tooth disease associated with myelin protein zero gene variants in Japan.

We aimed to reveal the genetic features associated with MPZ variants in Japan. From April 2007 to August 2017, 64 patients with 23 reported MPZ variants and 21 patients with 17 novel MPZ variants were investigated retrospectively. Variation in MPZ variants and the pathogenicity of novel variants was examined according to the American College of Medical Genetics standards and guidelines. Age of onset, cranial nerve involvement, serum creatine kinase (CK), and cerebrospinal fluid (CSF) protein were also analyzed. We identified 64 CMT patients with reported MPZ variants. The common variants observed in Japan were different from those observed in other countries. We identified 11 novel pathogenic variants from 13 patients. Six novel MPZ variants in eight patients were classified as likely benign or uncertain significance. Cranial nerve involvement was confirmed in 20 patients. Of 30 patients in whom serum CK levels were evaluated, eight had elevated levels. Most of the patients had age of onset >20 years. In another subset of 30 patients, 18 had elevated CSF protein levels; four of these patients had spinal diseases and two had enlarged nerve root or cauda equina. Our results suggest genetic diversity across patients with MPZ variants.

Preauricular retromandibular trans tympanic plate and styloid process keyhole approach to parapharyngeal lesions: a laboratory study.

BACKGROUND: The surgical removal of the infratemporal parapharyngeal lesions (IPL) is challenging due to its anatomical complexity. Previous surgical approaches have often been too invasive and necessitated sacrifice of normal function and anatomical structures, particularly in the retromandibular nerve region. Therefore, we sought to identify an approach corridor to this area that requires less sacrifice and report an innovative approach through a retromandibular fossa route to the IPL. METHODS: Five cadaveric specimens were dissected bilaterally with a trans-tympanic plate and styloid process approach. These specimens were investigated microanatomically and morphometrically to examine the extent of the approach in the parapharyngeal space. The clinical application of this approach was compared to previous approaches to the IPL used in our clinical series of 20 cases. RESULTS: Using this novel approach, the inferior alveolar nerve was identified in all specimens, while the chorda tympani and lingual nerve were identified in 6 (60%) and 4 (40%) dissections, respectively. In all specimens, the petrous portion of the internal carotid artery and the exit of the lower cranial nerve were identified. The average length of the exposed lower cranial nerves was 16.6 ± 3.8 mm (range: 11-25 mm). CONCLUSIONS: The described approach is feasible for accessing the IPL at the retromandibular nerve and is less invasive than conventionally used approaches.

Pbx loss in cranial neural crest, unlike in epithelium, results in cleft palate only and a broader midface.

Orofacial clefting represents the most common craniofacial birth defect. Cleft lip with or without cleft palate (CL/P) is genetically distinct from cleft palate only (CPO). Numerous transcription factors (TFs) regulate normal development of the midface, comprising the premaxilla, maxilla and palatine bones, through control of basic cellular behaviors. Within the Pbx family of genes encoding Three Amino-acid Loop Extension (TALE) homeodomain-containing TFs, we previously established that in the mouse, Pbx1 plays a preeminent role in midfacial morphogenesis, and Pbx2 and Pbx3 execute collaborative functions in domains of coexpression. We also reported that Pbx1 loss from cephalic epithelial domains, on a Pbx2- or Pbx3-deficient background, results in CL/P via disruption of a regulatory network that controls apoptosis at the seam of frontonasal and maxillary process fusion. Conversely, Pbx1 loss in cranial neural crest cell (CNCC)-derived mesenchyme on a Pbx2-deficient background results in CPO, a phenotype not yet characterized. In this study, we provide in-depth analysis of PBX1 and PBX2 protein localization from early stages of midfacial morphogenesis throughout development of the secondary palate. We further establish CNCC-specific roles of PBX TFs and describe the developmental abnormalities resulting from their loss in the murine embryonic secondary palate. Additionally, we compare and contrast the phenotypes arising from PBX1 loss in CNCC with those caused by its loss in the epithelium and show that CNCC-specific Pbx1 deletion affects only later secondary palate morphogenesis. Moreover, CNCC mutants exhibit perturbed rostro-caudal organization and broadening of the midfacial complex. Proliferation defects are pronounced in CNCC mutants at gestational day (E)12.5, suggesting altered proliferation of mutant palatal progenitor cells, consistent with roles of PBX factors in maintaining progenitor cell state. Although the craniofacial skeletal abnormalities in CNCC mutants do not result from overt patterning defects, osteogenesis is delayed, underscoring a critical role of PBX factors in CNCC morphogenesis and differentiation. Overall, the characterization of tissue-specific Pbx loss-of-function mouse models with orofacial clefting establishes these strains as unique tools to further dissect the complexities of this congenital craniofacial malformation. This study closely links PBX TALE homeodomain proteins to the variation in maxillary shape and size that occurs in pathological settings and during evolution of midfacial morphology.

MR Neurographic Evaluation of Facial and Neck Pain: Normal and Abnormal Craniospinal Nerves below the Skull Base.

Cranial nerve disease outside the skull base is a common cause of facial and/or neck pain, which causes significant disability for patients and frustration for clinicians. Neuropathy in this region can be traumatic, idiopathic, or iatrogenic secondary to dental and surgical procedures. MR neurography is a modification of conventional MRI techniques dedicated to evaluation of peripheral nerves and is being increasingly used for imaging of peripheral neuropathies at various sites in the body. MR neurography facilitates assessment of different causes of craniofacial pain and cranial nerves and allows elegant depiction of a multitude of regional neuropathies. This article discusses the anatomy, pathologic conditions, and imaging findings of the commonly implicated but difficult to image infratentorial nerves, such as the peripheral trigeminal nerve and its branches, facial nerve, glossopharyngeal nerve, vagus nerve, hypoglossal nerve, and greater and lesser occipital nerves. ©RSNA, 2018.

Evaluation of an animation tool developed to supplement dental student study of the cranial nerves.

INTRODUCTION: The structure/function of the cranial nerves is a core topic for dental students. However, due to the perceived complexity of the subject, it is often difficult for students to develop a comprehensive understanding of key concepts using textbooks and models. It is accepted that the acquisition of anatomical knowledge can be facilitated by visualisation of structures. This study aimed to develop and assess a novel cranial nerve animation as a supplemental learning aid for dental students. MATERIALS AND METHODS: A multidisciplinary team of anatomists, neuroscientists and a computer scientist developed a novel animation depicting the cranial nerves. The animation was viewed by newly enrolled first-year dental students, graduate entry dental students (year 1) and dental hygiene students (year 1). A simple life scenario employing the use of the cranial nerves was developed using a cartoon-type animation with a viewing time of 3.58 minutes. The animation was developed with emphasis on a life scenario. The animation was placed online for 2 weeks with open access or viewed once in a controlled laboratory setting. Questionnaires were designed to assess the participants' attitude towards the animation and their knowledge of the cranial nerves before and after visualisation. This study was performed before the delivery of core lectures on the cranial nerves. RESULTS: Our findings indicate that the use of the animation can act as a supplemental tool to improve student knowledge of the cranial nerves. Indeed, data indicate that a single viewing of the animation, in addition to 2-week access to the animation, can act as a supplemental learning tool to assist student understanding of the structure and function of cranial nerves. The animation significantly enhanced the student's opinion that their cranial nerve knowledge had improved. From a qualitative point of view, the students described the animation as an enjoyable and useful supplement to reading material/lectures and indicated that the animation was a useful tool in understanding the cranial nerves. CONCLUSION: Overall, these findings indicate that an animation demonstrating the cranial nerves in a simple, everyday functional scenario may act as a learning aid in the study of cranial nerves.

SBF1 mutations associated with autosomal recessive axonal neuropathy with cranial nerve involvement.

Biallelic mutations in the SBF1 gene have been identified in one family with demyelinating Charcot-Marie-Tooth disease (CMT4B3) and two families with axonal neuropathy and additional neurological and skeletal features. Here we describe novel sequence variants in SBF1 (c.1168C>G and c.2209_2210del) as the potential causative mutations in two siblings with severe axonal neuropathy, hearing loss, facial weakness and bulbar features. Pathogenicity of these variants is supported by co-segregation and in silico analyses and evolutionary conservation. Our findings suggest that SBF1 mutations may cause a syndromic form of autosomal recessive axonal neuropathy (AR-CMT2) in addition to CMT4B3.

Insertion of intra-oral electrodes for cranial nerve monitoring using a Crowe-Davis retractor.

Acoustic neuroma resection is an example of a neurosurgical procedure where the brainstem and multiple cranial nerves are at risk for injury. Electrode placement for monitoring of the glossopharyngeal and hypoglossal nerves during acoustic neuroma resection can be challenging. The purpose of this report is to illustrate the use of a device for intra-oral electrode placement for intraoperative monitoring of the glossopharyngeal and hypoglossal nerves. A 60-year-old male presented for acoustic neuroma resection. Under general anesthesia, a Crowe-Davis retractor was used to open the mouth, providing access to the posterior pharynx. For glossopharyngeal monitoring, two bent subdermal needle electrodes were inserted just lateral to the uvula. Two additional electrodes were inserted on the lateral tongue to monitor the hypoglossal nerve. Cranial nerves monitoring was conducted utilizing both free running and triggered electromyography of the trigeminal and facial nerves in addition to the lower cranial nerves. The tumor was resected successfully. Monitoring of the cranial nerves (including the glossopharyngeal and hypoglossal nerves) revealed no concerning responses. The Crowe-Davis retractor and the technique described allowed insertion of electrodes for neural monitoring, contributing to neural preservation.

Pterygopalatine Fossa Anatomy for a Surgical Approach to Sphenopalatine Ganglion.

The sphenopalatine ganglion is an extracranial neural structure within the pterygopalatine fossa. Modulation of this region via implantation of a neuromodulatory device presents a novel therapy for the treatment of facial and head pain. Yet sex, race, and genetic factors contribute to morphological variations between individuals. This study defines the standards and variations of the bony landmarks surrounding the pterygopalatine fossa. One hundred dry skulls were analyzed from the Hamann-Todd osteological collection. Ten anatomical dimensions were measured on each side of the face for each specimen (vidian foramen, zygomatic buttress, zygomatic maxillary suture, pyriform rim, infraorbital rim, pterygoid maxillary suture, greater palatine foramen, auditory canal, and pterygoid fossa). A statistical analysis was performed for both sides of the face based on sex and race. When stratified by sex, 7 of the 10 measurements revealed a statistically significant difference bilaterally. When stratified by race, 5 of the 10 measurements demonstrated a statistically significant difference bilaterally. Both male and African American skulls showed greater hemifacial values bilaterally when compared with their respective counterparts. The only statistically significant measurement on both the left and right sides of all skulls was the length from the vidian foramen to the infraorbital rim. Defining the anatomical mean distance between skull landmarks and highlighting differences between sex and race not only provides further insight into relative skull anatomy, but also sets the stage for device innovation.

Considerations on the etiology of congenital Brown syndrome.

PURPOSE OF REVIEW: Brown syndrome is an ocular motility disorder characterized by limited volitional and passive elevation of the eye in adduction. Although originally thought due to abnormalities in the trochlea or tendon sheath (limiting the free movement of the tendon through the trochlea), recent evidence suggests that some cases of congenital Brown syndrome may be related to neurodevelopmental abnormalities of the extraocular muscles (congenital cranial dysinnervation disorders, CCDD). RECENT FINDINGS: CCDD is a term encompassing congenital abnormalities of eye movements caused by congenital innervational abnormalities. The abnormal development of cranial nerve nuclei or abnormalities in cranial nerve axonal transport affects the development of the extraocular muscle(s). Currently, congenital fibrosis of the extraocular muscles, Duane syndrome, Moebius syndrome, Horizontal gaze palsy and progressive scoliosis, and synergistic divergence are included as CCDDs. In addition, congenial ptosis, Jaw Wink ptosis, and congenital superior oblique palsy are also included. Recently, it has been suggested that some cases of congenital Brown syndrome and congenital superior oblique paresis are related, and these entities may be part of the CCDDs spectrum. SUMMARY: Important findings regarding the cause of congenital Brown syndrome will be reviewed.

Roles of innervation in developing and regenerating orofacial tissues.

The head is innervated by 12 cranial nerves (I-XII) that regulate its sensory and motor functions. Cranial nerves are composed of sensory, motor, or mixed neuronal populations. Sensory neurons perceive generally somatic sensations such as pressure, pain, and temperature. These neurons are also involved in smell, vision, taste, and hearing. Motor neurons ensure the motility of all muscles and glands. Innervation plays an essential role in the development of the various orofacial structures during embryogenesis. Hypoplastic cranial nerves often lead to abnormal development of their target organs and tissues. For example, Möbius syndrome is a congenital disease characterized by defective innervation (i.e., abducens (VI) and facial (VII) nerves), deafness, tooth anomalies, and cleft palate. Hence, it is obvious that the peripheral nervous system is needed for both development and function of orofacial structures. Nerves have a limited capacity to regenerate. However, neural stem cells, which could be used as sources for neural tissue maintenance and repair, have been found in adult neuronal tissues. Similarly, various adult stem cell populations have been isolated from almost all organs of the human body. Stem cells are tightly regulated by their microenvironment, the stem cell niche. Deregulation of adult stem cell behavior results in the development of pathologies such as tumor formation or early tissue senescence. It is thus essential to understand the factors that regulate the functions and maintenance of stem cells. Yet, the potential importance of innervation in the regulation of stem cells and/or their niches in most organs and tissues is largely unexplored. This review focuses on the potential role of innervation in the development and homeostasis of orofacial structures and discusses its possible association with stem cell populations during tissue repair.

[New method of conduction anesthesia in the maxilla].

There was the research aimed at improving the effeciency of intraosseous anesthesia in the maxilla by blocking the infraorbital nerve conduction along its entire length. In the experimental part of the needle puncture defined place and character of the spreading of contrast medium into the upper jaw. In the clinical part of the study shows the advantages of the proposed method of intraosseous anesthesia.

Comparison of the study performance of dental students in different subfields of neuroanatomy at the Charité - Universitätsmedizin Berlin and evaluation of the neuroanatomy course in the fourth preclinical semester.

INTRODUCTION: The dentist's main working area is the head and neck region, which is innervated by the cranial nerves. On a daily basis, dentists must administer local anaesthesia to ensure pain-free treatment and differentiate between dental pain and neuropathies to avoid mistreatment. Therefore, neuroanatomical training, especially on the cranial nerves, is of immense importance for clinical practice. In order to adopt the curriculum, it is essential to constantly evaluate the quality of the training and to investigate whether there is a correlation between the students' performance and the relevance of the subfields to their work. MATERIAL AND METHODS: To address this issue, the results of MC exams in the neuroanatomy course for dental students at Charité-Universitätsmedizin Berlin from winter semester 2014/2015 to winter semester 2019/2020 were analysed. Each question was assigned to a specific subfield of neuroanatomy. We then compared cranial nerves and cranial nerve nuclei (clinically relevant) with the remaining subfields (clinically less/not relevant) to investigate whether students performed better in anatomy subfields that are more aligned with the clinical practice of a dentist. We also conducted an anonymous survey (n=201) of the dental students. RESULTS: From winter semester 2014/2015 to winter semester 2019/2020, students performed significantly (***, p< 0.001) better on the clinically relevant questions of the MC examination than on the less/not clinically relevant questions. However, when looking at each of the eleven semesters separately, only three semesters actually performed significantly better on the clinically relevant questions. Our survey also showed that students perceived the subfield of cranial nerves and cranial nerve nuclei to be the most relevant and studied it more intensively out of their own interest. DISCUSSION: The study showed that students perceived the subfield of cranial nerves and cranial nerve nuclei to be the most relevant. However, there was no direct correlation between student performance and clinically relevant questions. Using student performance alone as an indicator of relevance is not optimal, as factors such as motivation to learn can have a significant impact. CONCLUSION: Greater clinical relevance influences what students learn more intensively out of their own interest, but does not influence the results of the MC examination in favour of the subspecialty. Based on the available evidence, it is recommended that the structure of the neuroanatomy course be reconsidered.

Laboratory training in the retrosigmoid approach using cadaveric silicone injected cow brain.

BACKGROUND: A neurosurgical laboratory training model is designed for trainees in microneurosurgery to learn to handle surgical microscopes and microneurosurgical instruments. The silicone injection of a fresh cadaveric cow cranium is an alternative to using a cadaveric human brain for becoming familiar with the cerebellopontine angle (CPA) via the retrosigmoid approach. To report an improved method for training in the CPA via the retrosigmoid approach, using a fresh cadaveric cow cranium injected with silicone. METHODS: The material consists of a cadaveric cow brain injected with silicone. Preparation consists of irrigation of the major vessels followed by injection of silicone, coloured either red or blue. RESULTS: A three-step approach was designed to simulate microneurosurgical dissection along with the cerebellopontine angle and to dissect cranial nerves emerging from the brain stem. CONCLUSION: This laboratory training model is useful in allowing trainees to gain experience with the use of an operating microscope and familiarity with the CPA via the retrosigmoid approach. The aim of this study was to develop a novel model and to adapt it to create a life-like neurosurgical training system.

Head and neck blocks in infants, children, and adolescents.

This review will discuss the use of peripheral nerve blocks of the head and neck and its application to the practice of pediatric anesthesia using simple, landmark based approaches.

Multiple cranial nerve motor deficits, resembling polyneuritis cranialis, in a cat with hyperthyroidism.

A 14 plus-year-old (exact age unknown) neutered female domestic shorthair cat presented with a 6-day history of rapidly evolving difficulty in eating, dropped jaw, protrusion of the tongue, sialosis, change in voice (meow softer and higher pitched) and mild variable pelvic limb weakness. Salient clinical features were a left thyroid nodule, 2/6 systolic cardiac murmur, poor body condition, hypertension, bilateral retinal haemorrhages and an increased total thyroid hormone level consistent with a diagnosis of hyperthyroidism (HT). Neurological examination disclosed mild generalised weakness, bilateral visual deficits attributable to a hypertensive retinopathy and multiple cranial nerve (CN) motor deficits that included; mandibular paresis (CN V), bilateral external ophthalmoparesis (CNs III, IV, VI), bilateral facial paresis (CN VII), dysphagia (CNs IX, X), dysphonia (CN XI) and symmetrical paresis of the tongue (CN XII). Treatment with carbimazole, and subsequently, a modified extracapsular bilateral thyroidectomy resulted in a rapid improvement in neurological signs over 13 days and complete resolution by 100 days post thyroidectomy. To the best of the authors' knowledge, this is the first description of multiple CN motor deficits in a cat with HT and resembles polyneuritis crainialis that has recently been described in human patients with this disorder. It is suggested the underlying pathogenesis is a thyrotoxic polyneuropathy selectively affecting CN motor function, that HT needs to be considered in cats that might present with such signs and that resolution can occur with successful treatment of the HT.

Expression patterns of the Tmem16 gene family during cephalic development in the mouse.

Tmem16a, Tmem16c, Tmem16f, Tmem16h and Tmem16k belong to the newly identified Tmem16 gene family encoding eight-pass transmembrane proteins. We have analyzed the expression patterns of these genes during mouse cephalic development. In the central nervous system, Tmem16a transcripts were abundant in the ventricular neuroepithelium, whereas the other Tmem16 family members were readily detectable in the subventricular zone and differentiating fields. In the rostral spinal cord, Tmem16f expression was highest in the motor neuron area. In the developing eye, the highest amounts of Tmem16a transcripts were detected in the lens epithelium, hyaloid plexus and outer layer of the retina, while the other family members were abundant in the retinal ganglionic cell layer. Interestingly, throughout development, Tmem16a expression in the inner ear was robust and restricted to a subset of cells within the epithelium, which at later stages formed the organ of Corti. The stria vascularis was particularly rich in Tmem16a and Tmem16f mRNA. Other sites of Tmem16 expression included cranial nerve and dorsal root ganglia, meningeal precursors and the pituitary. Tmem16c and Tmem16f transcripts were also patent in the submandibular autonomic ganglia. A conspicuous feature of Tmem16a was its expression along the walls of blood vessels as well as in cells surrounding the trigeminal and olfactory nerve axons. In organs developing through epithelial-mesenchymal interactions, such as the palate, tooth and tongue, the above five Tmem16 family members showed interesting dynamic expression patterns as development proceeded. Finally and remarkably, osteoblasts and chondrocytes were particularly loaded with Tmem16a, Tmem16c and Tmem16f transcripts.

The relationship between posture and equilibrium and the auriculotemporal nerve in patients with disturbed gait and balance.

Balance is defined as a state of equilibrium or parity characterized by cancellation of all forces by equal opposing factors. This is the act of maintaining an upright posture (static balance) or in locomotion (dynamic balance or gait). This system depends on vestibular function, vision, and proprioception to maintain posture, to navigate in one's surroundings, to coordinate motion of body parts, to modulate fine motor control, and to initiate the vestibuloculomotor reflexes. These parts of the vestibular system provide our brains with information about changes in head movement with respect to the pull of gravity. Besides the visual, vestibular, and skeletal systems, which contribute to balance disorders, the dental (stomatognathic) system may also contribute to balance disorders. It is when all four of these systems are in coordination with one another, that a person will maintain equilibrium and balance, proper gait, and posture. The current article demonstrates, through normal anatomical and neurological processes, how the stomatognathic system influences these activities.