Imaging the cranial nerves: Part I: Methodology, infectious and inflammatory, traumatic and congenital lesions

Abstract

Many disease processes manifest either primarily or secondarily by cranial nerve deficits. Neurologists, ENT surgeons, ophthalmologists and maxillo-facial surgeons are often confronted with patients with symptoms and signs of cranial nerve dysfunction. Seeking the cause of this dysfunction is a common indication for imaging. In recent decades we have witnessed an unprecedented improvement in imaging techniques, allowing direct visualization of increasingly small anatomic structures. The emergence of volumetric CT scanners, higher field MR scanners in clinical practice and higher resolution MR sequences has made a tremendous contribution to the development of cranial nerve imaging. The use of surface coils and parallel imaging allows sub-millimetric visualization of nerve branches and volumetric 3D imaging. Both with CT and MR, multiplanar and curved reconstructions can follow the entire course of a cranial nerve or branch, improving tremendously our diagnostic yield of neural pathology. This review article will focus on the contribution of current imaging techniques in the depiction of normal anatomy and on infectious and inflammatory, traumatic and congenital pathology affecting the cranial nerves. A detailed discussion of individual cranial nerves lesions is beyond the scope of this article.

Visualization of the Peripheral Branches of the Mandibular Division of the Trigeminal Nerve on 3D Double-Echo Steady-State with Water Excitation Sequence

“…Following the entire course of the cranial nerves, including the extracranial segments, however, is still a diagnostic challenge in routine clinical practice. 1,2,[11][12][13][14][15][16] Intracranial segments of the cranial nerves, particularly the cisternal segments, are readily detected by using high-resolution heavily T2-weighted imaging. 14,15 Without the high-signal background from the CSF, however, heavily T2-weighted imaging has not proved to be very useful in visualizing the extracranial segments of the cranial nerves.…”

Imaging the hypoglossal nerve

“…The principles of designing a MR protocol for the hypoglossal nerve follow the same basic principles as for the other cranial nerves [7,[13][14][15]38] (Table 2).…”

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“…The vestibular nerves may be identified separately or as one only nerve. The latter case is considered an anatomic variant as seen in our case [8].…”