Abstract
The cranial nerves, which represent extensions of the functional structures of the brain, traverse the head and neck. They are connected to various cranial structures and are associated with several diseases. An in-depth understanding of their complex anatomy and normal imaging appearance allows the examiner to identify and characterize abnormalities with greater precision. One important tool for evaluating the cranial nerves is contrast-enhanced magnetic resonance imaging, especially that employing three-dimensional steady-state free precession sequences, which provide high soft-tissue and spatial resolution, despite the slen-derness of the nerves. In most cases of cranial nerve abnormalities, the imaging findings are nonspecific. Therefore, to narrow the differential diagnosis, it is necessary to take a full patient history, perform a focused physical examination, and order laboratory tests. In this pictorial essay, we review, illustrate, and discuss, from a pathophysiological perspective, infectious, neoplastic, and demyelinating disorders, as well as other inflammatory disorders, affecting the cranial nerves, the aim being to provide a practical, tangible reference for radiologists to use in daily practice.
Highlights
Infections of the central nervous system (CNS) are common, arising from hematogenous dissemination, contiguous propagation, traumatic injuries, or surgical manipulation
We review, illustrate, and discuss, from a pathophysiological perspective, infectious, neoplastic, and demyelinating disorders, as well as other inflammatory disorders, affecting the cranial nerves, the aim being to provide a practical, tangible reference for radiologists to use in daily practice
0100-3984 © Colégio Brasileiro de Radiologia e Diagnóstico por Imagem magnetic resonance imaging (MRI), abnormal leptomeningeal enhancement along cerebral surfaces and the cisternal segments of cranial nerves is a hallmark of infection and should be correlated with the results of cerebrospinal fluid (CSF) analysis
Summary
Infections of the central nervous system (CNS) are common, arising from hematogenous dissemination, contiguous propagation (usually from the paranasal sinuses, temporal bone, or skull base), traumatic injuries, or surgical manipulation. Those most frequently affected are the optic, trochlear, trigeminal, abducens, and facial nerves (cranial nerves II, IV, V, VI, and VII, respectively). Inflammatory and demyelinating diseases may arise from parainfectious and autoimmune processes, presenting with a monophasic, relapsing–remitting, or progressive course Some of these diseases may cause cranial nerve thickening and abnormal enhancement. In a previous article[1], we reviewed congenital, traumatic, and vascular diseases of the cranial nerves This pictorial essay goes further, illustrating infectious, neoplastic, and demyelinating diseases, as well as other inflammatory diseases. All of the pathologic conditions we review in this paper share the common finding of abnormal contrast enhancement in cranial nerves, each has specific epidemiological, clinical, biochemical, and imaging findings
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