Radiología. 2019;61(2):99---123 www.elsevier.es/rx UPDATE IN RADIOLOGY Cranial nerve disorders: Clinical manifestations and topographyଝ a,∗ a b c M. Jorquera Moya , S. Merino Menéndez , J. Porta Etessam , J. Escribano Vera , a M. Yus Fuertes a Sección de Neurorradiología, Hospital Clínico San Carlos, Madrid, Spain b Servicio de Neurología, Hospital Clínico San Carlos, Madrid, Spain c Neurorradiología, Hospital Ruber Internacional, Madrid, Spain Received 17 November 2017; accepted 27 September 2018 KEYWORDS Abstract The detection of pathological conditions related to the twelve cranial pairs rep- Cranial pairs; resents a significant challenge for both clinicians and radiologists; imaging techniques are Cranial nerves; fundamental for the management of many patients with these conditions. In addition to knowl- Cranial neuropathies; edge about the anatomy and pathological entities that can potentially affect the cranial pairs, Neuralgia; the imaging evaluation of patients with possible cranial pair disorders requires specific exami- Cranial nerve palsy nation 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. © 2018 SERAM. Published by Elsevier Espana,˜ S.L.U. All rights reserved. PALABRAS CLAVE Sintomatología derivada de los pares craneales: Clínica y topografía Pares craneales; Resumen La detección de la patología relacionada con los doce pares craneales representa Nervios craneales; un importante desafío, tanto para los clínicos como para los radiólogos. Las técnicas de imagen Neuropatía de pares craneales; son fundamentales para el manejo de muchos de los pacientes. Adicionalmente al conocimiento Neuralgia; anatómico y de las entidades patológicas que potencialmente puedan afectarlos, la evaluación Parálisis por imagen de los pares craneales requiere protocolos de exploración y técnicas de adquisición y procesado específicas. ଝ Please cite this article as: Jorquera Moya M, Merino Menéndez S, Porta Etessam J, Escribano Vera J, Yus Fuertes M. Sintomatología derivada de los pares craneales: Clínica y topografía. Radiología. 2019;61:99---123. ∗ Corresponding author. E-mail address: [email protected] (M. Jorquera Moya). 2173-5107/© 2018 SERAM. Published by Elsevier Espana,˜ S.L.U. All rights reserved. 100 M. Jorquera Moya et al. En este artículo se efectúa un repaso de los principales síntomas y síndromes relacionados con los nervios craneales que pueden precisar la realización de pruebas de imagen y la patología sub- yacente, así como una breve revisión de la anatomía y de las técnicas de imagen más adecuadas a la indicación. © 2018 SERAM. Publicado por Elsevier Espana,˜ S.L.U. Todos los derechos reservados. Anatomy of memory The 2D FSE T1, T1 post-contrast and T2 with fat suppres- sion and post-contrast sequences 3D T1 with fat suppression make it possible to evaluate the cisternal, foraminal and There are 12 pairs of cranial nerves that connect the brain extraforaminal segments, and the course in the craniofacial stem with structures of the head and neck and the thoracic region of the terminal branches of the cranial nerves. and abdominal cavities. Table 1 summarises the anatomical In neurovascular compression syndromes, angiographic course of cranial nerves III to XII. sequences are useful, mainly 3D TOF. The visualisation of the There are three types according to their function: images co-registered with the FIESTA/CISS sequence facil- sensory, motor and mixed nerves. Table 2 lists the nomencla- 7 itates the interpretation of the findings. The sequences ture, function and clinical semiology of the cranial nerves. of time-resolved imaging of contrast kinetics (TRICKS) In each cranial nerve, the intra-axial (nucleus and fasci- are especially indicated when a dural fistula or AVM is cle), cisternal, dural and interdural, bony or foraminal and 1 suspected.8 extraforaminal segments are differentiated. The nuclei are The nerves of greater section allow for their microstruc- distributed from the midbrain to the proximal cervical cord. 9 tural evaluation by means of diffusion tensor sequencing. The cisternal segment has two parts, a central one, Tractography can be useful in locating some of the nerves myelinated by oligodendrocytes, and a peripheral one whose that are difficult to identify in the case of expansive myelin is formed by Schwann cells. Between both segments 10 processes. Table 3 summarises the main sequences that is the transition or Steiner-Redlich zone, variable from one must be performed in case of pathology of the cranial pair to another, more vulnerable to neurovascular compres- nerves. sion and threshold for the location of schwannomas (distal Computed tomography (CT) complements magnetic res- to this). onance imaging (MRI), which allows us to evaluate the In some nerves, a dural segment can be identified, foramina and intraosseous trajectories of the cranial nerves located in a dural evagination with cerebrospinal fluid (CSF) at the base of the skull, especially the petrous apex content such as Meckel’s cave. (Figs. 1 and 2). The interdural segment is located between two dura mater sheets and is occupied by venous plexuses such as the cavernous sinus. Semiology and pathology of cranial nerves I The foraminal segment, also surrounded by venous plexuses, is located at the base of the skull. and II The extraforaminal segment corresponds to the extracranial nerve course. Nerves I (olfactory nerve) and II (optic nerve) are considered prolongations of white matter tracts of the central nervous system. They do not follow the anatomical classification or Imaging techniques division into the same segments as the rest of the cranial nerves; nor do they share the same pathology, so clinical Magnetic resonance imaging (MRI) is the technique of choice semiology and pathology will be dealt with separately. for the evaluation of cranial nerves. The intra-axial segment can be evaluated by means of the usual sequences for the study of the brain. The Olfactory disorders remaining segments require specific sequences, and these are the SSFP (Steady-State Free Precession), named as 3D The olfactory nerve consists of a set of unmyelinated nerve FIESTA/CISS, Fast Imaging Employing Steady-state Acqui- fillets that arise from the olfactory portion of the pituitary sition/Constructive Interference Steady State sequences, mucosa in the roof of the nostril; said fillets cross the lam- which demonstrate the cranial nerves in their cisternal path, ina cribrosa and end in the ventral region of the olfactory and when post-contrast has been performed, the interdu- bulb where they synapse with the second neuron (Fig. 1). ral and foraminal trajectories by the enhancement of the The efferent axons leave the olfactory bulb and reach the 2 --- 4 venous plexuses. olfactory cortex through the olfactory tract. The 3D FLAIR sequence makes it possible to see Anosmia can occur due to injury at any location of the the cistern segments and the detection of post-contrast olfactory pathway. When it is unilateral, the location is prox- 5,6 enhancements in these and in the meninges. imal to the piriform cortex. The most common causes are Cranial Table 1 Anatomy of the cranial nerves. nerve Cranial nerve Nucleus Apparent source Cisternal segment Dural/interdural Foraminal segment Extracranial segment segment disorders: III nerve Midbrain anterior to Interpeduncular fossa Interpeduncular and Cavernous sinus: Superior orbital Orbital apex: annulus Common ocular aqueduct, at the level of prepontine cistern upper region of fissure of Zinn motor nerve the superior Between posterior the lateral wall It is divided into Clinical quadrigeminal tubercle cerebral arteries upper and lower (upper) and superior branches cerebellar arteries (lower) manifestations IV nerve Midbrain: dorsal to MLF Dorsal surface Ambient and Cavernous sinus: Superior orbital Orbital apex: annulus Trochlear nerve and ventral to inferior to quadrigeminal cistern inferior lateral fissure of Zinn periaqueductal grey contralateral up to the margin of wall to III nerve matter at the level of quadrigeminal the tentorium the inferior tubercle and quadrigeminal tubercle topography V nerve 1 motor N: lateral Lateral region of the Prepontine cistern Meckel’s Cave V1: superior orbital V1: orbit Trigeminal nerve pontine tegmentum pons Division into three fissure Branches: lacrimal, 3 sensory N: from sensitive V2: greater foramen frontal and midbrain to C3 branches: rotundum nasociliary n. • V1 ophthalmic --- V3: foramen ovale V2: pterygopalatine lateral wall of the fossa-orbit through cavernous sinus inferior orbital fissure • V2 maxillary --- V3 + motor branch: lateral wall of the chewing space cavernous sinus • V3 mandibular joins the motor root VI nerve Pons near the midline at Bulboprotuberancial Superior course in Dorello’s canal on Superior orbital Orbit: external rectus External ocular the level of the tubercle groove prepontine cistern the back of the fissure muscle motor of the facial nerve that clivus protrudes the floor of IV Then inside of ventricle medial cavernous sinus to V1 VII nerve Ventrolateral pontine Bulboprotuberancial Cerebellopontine Intratemporal Stylomastoid foramen Parotid lateral to the Facial nerve tegmentum groove angle cistern • IAC retromandibular vein • Sensory n.: n. of the 2 nerves: facial