The trigeminal nerve: An illustrated review of its imaging anatomy and pathology

doi:10.1016/j.crad.2012.05.019

Clinical Radiology

Volume 68, Issue 2, February 2013, Pages 203-213

https://doi.org/10.1016/j.crad.2012.05.019 Get rights and content

The trigeminal nerve is the largest cranial nerve and has both sensory and motor components. Due to its extensive distribution in the head and neck, the nerve or its branches may be involved by a myriad of disease entities. Additionally, the nerve may act as a route of spread in various inflammatory and neoplastic diseases, underlining the need for a thorough understanding of its anatomy. A segmental division of the trigeminal system is preferred when interpreting imaging studies as both the type of lesion and symptoms may vary based on the site of involvement. These segments include the brainstem, cisternal, Meckel's cave, cavernous sinus, and peripheral divisions. In general, dedicated magnetic resonance imaging (MRI) is preferred to evaluate nerve dysfunction. In select cases, contrast medium administration, heavily T2-weighted sequences, or MR angiography may prove to be diagnostic. This review aims to review the anatomy of the trigeminal nerve briefly, followed by illustrations of various lesions that may present with trigeminal nerve dysfunction.

Introduction

The trigeminal nerve (TGN), also known as the fifth cranial nerve, is the principal nerve of the first brachial arch.¹ It is the largest cranial nerve and is extensively distributed in the supra hyoid neck.2, 3

Magnetic resonance imaging (MRI), supplemented with contrast-enhanced sequences in selected cases, is the preferred imaging technique to evaluate the TGN. However, computed tomography (CT) may be used in cases of trauma, to map the bony anatomy of skull base preoperatively, or in critically ill patients.⁴ Additionally, lesions causing bony destruction (malignant otitis externa, skull base osteomyelitis, Langerhans' cells histiocytosis), proliferation (fibrous dysplasia, chondrosarcoma), or remodelling (schwannomas, meningiomas) may be better assessed by a combination of CT and MRI.

Section snippets

Imaging anatomy of the TGN

The TGN is formed from three divisions: ophthalmic (V1), maxillary (V2), and mandibular (V3). V1 and V2 are purely sensory, while V3 has both sensory and motor components.² The extra-cranial branches of these divisions are summarized in Table 1.

V1 is the smallest division and is formed through coalescence of V1 branches posterior to the orbital apex.² More proximally, V1 enters the cavernous sinus. Similarly, V2 is formed by coalescence of V2 branches in the infraorbital canal and

Conditions affecting the TGN

Lesions affecting TGN function may involve the supratentorial compartment or it's nuclei in the brainstem. Alternately, the nerve may be affected in the prepontine cistern, Meckel's cave, cavernous sinus, or within the peripheral divisions or terminal branches. The clinical presentation varies depending on the site of involvement and may necessitate additional sequences or modification of routine protocol (Table 2).

Conclusion

The TGN is the largest cranial nerve. It may be involved by various lesions and can serve as a pathway of disease spread. A thorough understanding of its anatomy and pathology is of vital importance, both in diagnosis and staging of diseases.

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Pictorial ReviewThe trigeminal nerve: An illustrated review of its imaging anatomy and pathology

Introduction

Section snippets

Imaging anatomy of the TGN

Conditions affecting the TGN

Conclusion

Eur J Radiol

Neuroimaging Clin N Am

The trigeminal nerve

MR imaging of the trigeminal ganglion, nerve, and the perineural vascular plexus: normal appearance and variants with correlation to cadaver specimens

AJNR Am J Neuroradiol

Disorders of the trigeminal system

Semin Neurol

Trigeminal neuropathy: evaluation with MR imaging

RadioGraphics

Pictorial Review
The trigeminal nerve: An illustrated review of its imaging anatomy and pathology