Review

Authors: M Jorquera Moya, S Merino Menéndez, J Porta Etessam...

The detection of pathological conditions related to the twelve cranial pairs represents a significant challenge for both clinicians and radiologists; imaging techniques are fundamental for the management of many patients with these conditions. In addition to knowledge about the anatomy and pathological entities that can potentially affect the cranial pairs, the imaging evaluation of patients with possible cranial pair disorders requires specific examination protocols, acquisition techniques, and image processing. This article provides a review of the most common symptoms and syndromes related with the cranial pairs that might require imaging tests, together with a brief overview of the anatomy, the most common underlying processes, and the most appropriate imaging tests for different indications.

Topics: Cranial Nerve Diseases; Cranial Nerves; Humans; Magnetic Resonance Imaging; Symptom Assessment

PubMed: 30501996
DOI: 10.1016/j.rx.2018.09.005

Authors: Alan Taylor, Firas Mourad, Roger Kerry...

BACKGROUND

Neurological examination in musculoskeletal practice is a key element of safe and appropriate orthopedic clinical practice. With physiotherapists currently positioning themselves as advanced first line practitioners, it is essential that those who treat patients who present with neck/head/orofacial pain and associated symptoms, should have an index of suspicion of cranial nerve (CN) dysfunction. They should be able to examine and determine if CN dysfunction is present, and make appropriate clinical decisions based upon those findings.

METHODS

This paper summarizes the functions, potential impairments of the nerves, associated conditions, and basic skills involved in cranial nerve examination.

RESULTS

A summary of cranial nerve examination is provided, which is based on the function of the nerves, This is intended to facilitate clinicians to feel more confident at understanding neural function/impairment, as well as performing and interpreting the examination.

CONCLUSION

This paper illustrates that CN testing can be performed quickly, efficiently and without the need for complicated or potentially unavailable equipment. An understanding of the CN's function and potential reasons for impairment is likely to increase the frequency of CN testing in orthopedic clinical practice and referral if positive findings are encountered.

Topics: Cranial Nerves; Humans

PubMed: 34182898
DOI: 10.1080/10669817.2021.1937813

Authors: Christopher M Lack, Joseph Pena, Elizabeth X L Grubb...

INTRODUCTION

Medical students often struggle with learning cranial nerve anatomy. Typically, cranial nerve anatomy is taught using didactic lectures and textbook illustrations, often leaving students frustrated.

METHODS

We developed a multimodal radiologic approach to teaching cranial nerve anatomy. First, 150 students were presented with carefully curated preclass material from which to prepare. Next, they received a didactic lecture that was recorded for them to revisit on their own time. Last, students worked in groups in a lab setting with expert radiologists to identify the cranial nerves and related anatomy and learn about some basic pathophysiology. We used a pretest and posttest to examine the effectiveness of our teaching methods and a survey to measure students' satisfaction.

RESULTS

Student knowledge of cranial nerve structure was significantly improved after our module, with quiz scores increasing from 4.6 to 6.8 out of 9.0 ( < .001). In addition, students reported feeling more confident in their knowledge of the material and offered high satisfaction scores.

DISCUSSION

The breadth of knowledge covered during the preclinical training years continues to expand despite stable or even contracted durations of training, requiring knowledge to be delivered in an ever more efficient manner. Ultimately, the multimodal pedagogy used by our resource leads to students who are more confident and engaged in their learning, resulting in increased knowledge.

Topics: Cranial Nerves; Education, Medical, Undergraduate; Educational Measurement; Humans; Radiology; Students, Medical

PubMed: 35720637
DOI: 10.15766/mep_2374-8265.11261

Review

Authors: D Leclercq, J-B Thiebaut, F Héran...

Two different clinical entities, essential or secondary neuralgia, are associated with different pathologies. The pathways of CN V comprise the cervical spine, the brainstem, the root of the nerve and the three peripheral branches: V1, V2 and V3. The lesions responsible for neuralgia are neoplastic, vascular, inflammatory, malformative or post-traumatic. The examination protocol should explore the set of CN V pathways. Neurovascular compression is the main cause of essential neuralgia. It is investigated by T2-weighted inframillimetric volume. Two conditions are necessary to diagnose a neurovascular compression: localised on the root entry zone [(REZ), 2-6mm from the emergence of the pons] and perpendicularly. In the absence of neurovascular compression, thin slices and a gadolinium injection are necessary.

Topics: Cranial Nerve Neoplasms; Diagnosis, Differential; Humans; Image Enhancement; Image Interpretation, Computer-Assisted; Magnetic Resonance Imaging; Nerve Compression Syndromes; Neural Pathways; Neurologic Examination; Sensitivity and Specificity; Trigeminal Nerve; Trigeminal Nerve Diseases; Trigeminal Nerve Injuries; Trigeminal Neuralgia; Trigeminal Nuclei

PubMed: 24007773
DOI: 10.1016/j.diii.2013.08.002

Authors: A M Halawani, S Tohyama, P S-P Hung...

BACKGROUND AND PURPOSE

Vestibular schwannomas are common cerebellopontine angle tumors arising from the vestibulocochlear nerve and can result in cranial nerve dysfunction. Conventional MR imaging does not provide information that could correlate with cranial nerve compression symptoms of hearing loss or imbalance. We used multitensor tractography to evaluate the relationship between the WM microstructural properties of cranial nerves and tumor volume in a cohort of patients with vestibular schwannomas.

MATERIALS AND METHODS

A retrospective study was performed in 258 patients with vestibular schwannomas treated at the Gamma Knife clinic at Toronto Western Hospital between 2014 and 2018. 3T MR images were analyzed in 160 surgically naïve patients with unilateral vestibular schwannomas. Multitensor tractography was used to extract DTI-derived metrics (fractional anisotropy and radial, axial, and mean diffusivities of the bilateral facial and vestibulocochlear nerves [cranial nerves VII/VIII]). ROIs were placed in the transition between cisternal and intracanalicular segments, and images were analyzed using the eXtended Streamline Tractography reconstruction method. Diffusion metrics were correlated with 3D tumor volume derived from the Gamma Knife clinic.

RESULTS

DTI analyses revealed significantly higher fractional anisotropy values and a reduction in axial diffusivity, radial diffusivity, and mean diffusivity (all < .001) within the affected cranial nerves VII and VIII compared with unaffected side. All specific diffusivities (axial, radial, and mean diffusivity) demonstrated an inverse correlation with tumor volume (axial, radial, and mean diffusivity, < .01).

CONCLUSIONS

Multitensor tractography allows the quantification of cranial nerve VII and VIII WM microstructural alterations in patients with vestibular schwannomas. Our findings support the hypothesis that tumor volume may cause microstructural alterations of the affected cranial nerves VII and VIII. This type of advanced imaging may represent a possible avenue to correlate diffusivities with cranial nerve function.

Topics: Cranial Nerves; Facial Nerve; Humans; Neuroma, Acoustic; Retrospective Studies; Tumor Burden; Vestibulocochlear Nerve

PubMed: 34615646
DOI: 10.3174/ajnr.A7257

Authors: Rocio Orlandi, Rodrigo Gutierrez-Quintana, Beatrice Carletti...

BACKGROUND

Vestibular dysfunction is relatively common in dogs, with a prevalence of 0.08% reported in primary veterinary care in the UK. There are several studies investigating how to differentiate between peripheral and central vestibular disease but only limited information regarding the possible underlying causes for peripheral vestibular dysfunction in dogs. This study therefore aimed to describe the clinical signs, magnetic resonance imaging findings (MRI), underlying causes and outcome in a large population of dogs diagnosed with peripheral vestibular disease.

RESULTS

One hundred eighty-eight patients were included in the study with a median age of 6.9 years (range 3 months to 14.6 years). Neurological abnormalities included head tilt (n = 185), ataxia (n = 123), facial paralysis (n = 103), nystagmus (n = 97), positional strabismus (n = 93) and Horner syndrome (n = 7). The most prevalent diagnosis was idiopathic vestibular disease (n = 128), followed by otitis media and/or interna (n = 49), hypothyroidism (n = 7), suspected congenital vestibular disease (n = 2), neoplasia (n = 1) and cholesteatoma (n = 1). Long-term follow-up revealed persistence of head tilt (n = 50), facial paresis (n = 41) and ataxia (n = 6) in some cases. Recurrence of clinical signs was observed in 26 dogs. Increasing age was associated with a mild increased chance of diagnosis of idiopathic vestibular syndrome rather than otitis media and/or interna (P = 0.022, OR = 0.866; CI 0.765-0.980). History of previous vestibular episodes (P = 0.017, OR = 3.533; CI 1.251-9.981) was associated with an increased likelihood of resolution of the clinical signs whilst contrast enhancement of cranial nerves VII and/or VIII on MRI (P = 0.018, OR = 0.432; CI 0.251-0.868) was associated with a decreased chance of resolution of the clinical signs.

CONCLUSIONS

Idiopathic vestibular disease is the most common cause of peripheral vestibular dysfunction in dogs and it is associated with advanced age. Incomplete recovery from peripheral vestibular disease is common, especially in dogs presenting with cranial nerve enhancement on MRI but less so if there is previous history of vestibular episodes.

Topics: Age Factors; Animals; Cranial Nerves; Dog Diseases; Dogs; Female; Labyrinthitis; Magnetic Resonance Imaging; Male; Otitis Media; Retrospective Studies; Treatment Outcome; Vestibular Diseases

PubMed: 32450859
DOI: 10.1186/s12917-020-02366-8

Review

Authors: Alino Martínez-Marcos, José Ramón Sañudo

This Special Issue, entitled "Cranial Nerves: phylogeny, ontogeny, morphology and clinical significance," has been divided into two consecutive volumes. We present here the first volume, devoted to phylogeny and ontogeny. Articles in this volume examine these two topics from a microscopic point of view. This volume includes an historical review that serves as an introduction. It also includes a review of the organization of cranial nerves from a neuromeric perspective which, together with two articles in amphioxi and lampreys, give emphasis to a comparative approach. Finally, several articles examine cranial nerves zero (nervus terminalis), I (olfactory), II (optic), III, IV and VI (oculomotor), VIII (cochlear and vestibular), and XI (accessory or spinal). Together, they provide a general overview of the neuroanatomical organization of cranial nerves, while offering insights into an evo-devo paradigm. Anat Rec, 302:378-380, 2019. © 2019 Wiley Periodicals, Inc.

Topics: Biological Ontologies; Cranial Nerves; Humans; Phylogeny

PubMed: 30724480
DOI: 10.1002/ar.24072

Authors: Hiroshi Kurosaka, Paul A Trainor, Margot Leroux-Berger...

Cranial nerves govern sensory and motor information exchange between the brain and tissues of the head and neck. The cranial nerves are derived from two specialized populations of cells, cranial neural crest cells and ectodermal placode cells. Defects in either cell type can result in cranial nerve developmental defects. Although several signaling pathways are known to regulate cranial nerve formation our understanding of how intercellular signaling between neural crest cells and placode cells is coordinated during cranial ganglia morphogenesis is poorly understood. Sonic Hedgehog (Shh) signaling is one key pathway that regulates multiple aspects of craniofacial development, but whether it co-ordinates cranial neural crest cell and placodal cell interactions during cranial ganglia formation remains unclear. In this study we examined a new Patched1 (Ptch1) loss-of-function mouse mutant and characterized the role of Ptch1 in regulating Shh signaling during cranial ganglia development. Ptch1(Wig/ Wig) mutants exhibit elevated Shh signaling in concert with disorganization of the trigeminal and facial nerves. Importantly, we discovered that enhanced Shh signaling suppressed canonical Wnt signaling in the cranial nerve region. This critically affected the survival and migration of cranial neural crest cells and the development of placodal cells as well as the integration between neural crest and placodes. Collectively, our findings highlight a novel and critical role for Shh signaling in cranial nerve development via the cross regulation of canonical Wnt signaling.

Topics: Animals; Cell Death; Cell Movement; Cranial Nerves; Ectoderm; Facial Nerve; Hedgehog Proteins; Mice; Neural Crest; Patched Receptors; Patched-1 Receptor; Receptors, Cell Surface; Sequence Deletion; Trigeminal Nerve; Wnt Signaling Pathway

PubMed: 25799573
DOI: 10.1371/journal.pone.0120821

Authors: Duncan B Leitch, Diana K Sarko, Kenneth C Catania...

We investigated the relationship between body size, brain size, and fibers in selected cranial nerves in shrews and moles. Species include tiny masked shrews (S. cinereus) weighing only a few grams and much larger mole species weighing up to 90 grams. It also includes closely related species with very different sensory specializations - such as the star-nosed mole and the common, eastern mole. We found that moles and shrews have tiny optic nerves with fiber counts not correlated with body or brain size. Auditory nerves were similarly small but increased in fiber number with increasing brain and body size. Trigeminal nerve number was by far the largest and also increased with increasing brain and body size. The star-nosed mole was an outlier, with more than twice the number of trigeminal nerve fibers than any other species. Despite this hypertrophied cranial nerve, star-nosed mole brains were not larger than predicted from body size, suggesting that magnification of their somatosensory systems does not result in greater overall CNS size.

Topics: Animals; Body Size; Brain; Brain Mapping; Cranial Nerves; Moles; Nerve Fibers; Organ Size; Shrews; Species Specificity; Trigeminal Nerve

PubMed: 25174995
DOI: 10.1038/srep06241

Authors: Alino Martínez-Marcos, José Ramón Sañudo

This Special Issue entitled "Cranial Nerves: phylogeny, ontogeny, morphology and clinical significance" has been divided into two consecutive volumes. This second volume is devoted to morphology and clinical relevance. Articles in this volume examine these topics from a macroscopic point of view and with a surgical interest. This volume includes articles on oculomotor nerves III, IV, and VI and their course in the orbit; intracranial and extracranial views of the V and VII pairs; and branching patterns of IX, X, XI, and XII pairs with medical significance. Together, these articles provide a general overview of cranial nerves' gross anatomical organization, as well as improving on the knowledge necessary for clinical approaches. Anat Rec, 302:555-557, 2019. © 2019 Wiley Periodicals, Inc.

Topics: Cranial Nerves; Humans

PubMed: 30810281
DOI: 10.1002/ar.24106