Abducens nerve palsy in a congenital anomalous neurovascular development of the sixth cranial nerve and anterior inferior cerebellar artery: A case report

Abducens nerve palsy is a common ocular motor paralysis with a broad set of etiopathogenetic causes. Magnetic resonance imaging is a key diagnostic technique to investigate organic causes of sixth nerve palsy, as it allows a detailed representation of the course of the nerve, particularly in its intracisternal tract. Anatomical variants of the sixth cranial nerve comprise duplications and fenestrations in various traits. Anatomical variants of cerebellar arteries have also been described. We report the case of a patient with abducens nerve palsy presumably related to a neurovascular conflict due to a peculiar anatomical variant, which consists in a cerebellar artery passing through the intracisternal duplication of the abducens nerve.     

Magnetic resonance imaging in patients with diplopia. A review

Magnetic resonance imaging may be the procedure of choice for evaluating patients with diplopia; the absence of signals from cortical bone enables the brain stem and individual cranial nerves to be visualized and the imaging planes selected easily, and there is excellent contrast resolution of pathologic lesions. A clinical assessment of diplopia including the identification of associated neurologic disturbances is necessary prior to MR imaging, however, to assure that appropriate anatomic areas are studied and imaging sessions kept within acceptable time limits. The relevant physiology and anatomy critical to normal ocular motility are reviewed and the value of MR imaging for diplopia demonstrated by selected patient examples.     

Nerve Entrapment

Entrapment and compressive neuropathies are frequent clinical conditions occurring about the elbow. In most instances clinical and electromyograhic evaluation are adequate for patient management, but in some cases further evaluation with imaging techniques is required. Magnetic resonance imaging (MRI) has been shown to be useful in the evaluation of these conditions, especially to detect space occupying lesions. In this article, compressive neuropathies involving the ulnar, median, and radial nerves are discussed, with emphasis on the normal anatomy and the MRI depiction of pathologic findings.     

Female pelvis

Magnetic resonance imaging is gaining increasing importance in imaging of the female pelvis. This overview attempts to describe the various imaging strategies in the evaluation of gynecologic diseases, as well as the normal MR anatomy of the female genital organs. The MR indications for the assessment of various pathologic conditions, including characterization and staging of gynecologic neoplasms and prenatal diagnosis of fetal malformations, are discussed.     

3D-FIESTA观察活体眼运动神经及初步临床应用

目的运用三维快速平衡稳态成像（30-FIESTA）序列显示活体眼运动神经脑池段,同时与先天性眼外肌纤维化综合征（CFEOM）患者进行对照,探讨该序列的临床应用价值。资料与方法20名健康志愿者和3例来自同一家系的CFEOM患者分别行MRI检查,运用多平面重组（MPR）技术进行多维重组,分别在沿神经长轴的层面显示眼运动神经的走行和毗邻结构。结果20名志愿者,40侧动眼神经脑池段全程在斜矢状面、斜横断面及冠状面MR图像上显示清晰,显示率100％（40／40）;39侧外展神经脑池段全程在沿神经走行的各个断面均显示清晰,显示率97.5％（39／40）;25侧滑车神经脑池段（CN4）于中脑背侧下丘下外方水平出中脑进入环池,显示率62．5％（25／40）。3例（CFEOM组）眼运动神经脑池段均有不同程度发育不良。结论运用3D-FIESTA序列可以清晰显示各组眼运动神经脑池段,能够为眼运动神经发育异常提供直观的形态学依据,辅助临床诊断。     

Trigeminal neuralgia and facial nerve paralysis

The trigeminal nerve is the largest of the cranial nerves. It provides sensory input from the face and motor innervation to the muscles of mastication. The facial nerve is the cranial nerve with the longest extracranial course, and its main functions include motor innervation to the muscles of facial expression, sensory control of lacrimation and salivation, control of the stapedial reflex and to carry taste sensation from the anterior two-thirds of the tongue. In order to be able adequately to image and follow the course of these cranial nerves and their main branches, a detailed knowledge of neuroanatomy is required. As we are dealing with very small anatomic structures, high resolution dedicated imaging studies are required to pick up normal and pathologic nerves. Whereas CT is best suited to demonstrate bony neurovascular foramina and canals, MRI is preferred to directly visualize the nerve. It is also the single technique able to detect pathologic processes afflicting the nerve without causing considerable expansion such as is usually the case in certain inflammatory/infectious conditions, perineural spread of malignancies and in very small intrinsic tumours. Because a long course from the brainstem nuclei to the peripheral branches is seen, it is useful to subdivide the nerve in several segments and then tailor the imaging modality and the imaging study to that specific segment. This is particularly true in cases where topographic diagnosis can be used to locate a lesion in the course of these nerves.     

Imaging the hypoglossal nerve

The hypoglossal nerve is a pure motor nerve. It provides motor control to the intrinsic and extrinsic tongue muscles thus being essential for normal tongue movement and coordination. In order to design a useful imaging approach and a working differential diagnosis in cases of hypoglossal nerve damage one has to have a good knowledge of the normal anatomy of the nerve trunk and its main branches. A successful imaging evaluation to hypoglossal diseases always requires high resolution studies due to the small size of the structures being studied. MRI is the preferred modality to directly visualize the nerve, while CT is superior in displaying the bony anatomy of the neurovascular foramina of the skull base. Also, while CT is only able to detect nerve pathology by indirect signs, such as bony expansion of the hypoglossal canal, MRI is able to visualize directly the causative pathological process as in the case of small tumors, or infectious/inflammatory processes affecting the nerve. The easiest way to approach the study of the hypoglossal nerve is to divide it in its main segments: intra-axial, cisternal, skull base and extracranial segment, tailoring the imaging technique to each anatomical area while bearing in mind the main disease entities affecting each segment.     

The glossopharyngeal, vagus and spinal accessory nerves

The glossopharyngeal, vagus and spinal accessory nerves are closely related anatomically, and to a certain extent, functionally. We present an overview of their anatomy, highlighting the important clinical and imaging implications. The main pathologic lesions arising from these nerves are also discussed and the imaging features reviewed.     

Normal and pathologic radiographic anatomy of the motor innervation of the face

Facial motor disorders, including facial paralysis, myokymia, dyskinesia, and hemifacial spasm, are common clinical problems in which radiographic evaluation plays a crucial role. Since every segment of the motor innervation of the face from the brain to the parotid gland can now be seen radiographically, radiologists must understand the normal anatomy, the common pathologic lesions at each level, and the clinical findings that help localize the abnormality so that the most sensitive and accurate radiographic approach can be planned. Though computed tomography alone allows for visualization of every segment, other methods such as cisternography, angiography, polytomography, sialography, and magnetic resonance imaging are complementary in specific disorders.     

Magnetic resonance imaging of the pelvis

Magnetic resonance imaging (MRI) is a very promising modality for evaluation of the pelvis. Its major role appears likely to be the staging of known malignancies. In this article, the appearance of normal pelvic anatomy on MR scans is presented, as well as a discussion of the use of MRI in the detection and evaluation of pathologic conditions and a comparison of MRI with CT.     

Magnetic resonance imaging of the spine

Magnetic resonance imaging has been applied to the evaluation of the spine and foramen magnum and has clearly shown not only that it can demonstrate the normal spinal anatomy and a variety of pathologic conditions, but also that it can be performed safely in a noninvasive fashion in an outpatient setting. Although MRI is presently a valuable adjunct to more conventional diagnostic studies of the spine, it is the imaging examination of choice in several suspected disease entities.     

MR imaging of the kidney

Magnetic resonance imaging provides superb anatomic detail and greater sensitivity to the detection of most lesions than any other imaging modality. The topics covered in this article include the physical principles of MR imaging and imaging of normal renal anatomy and pathologic renal entities, including pathologic conditions of the renal hilum and renal masses.     

Comparison of 2D and 3D MRI of the optic and oculomotor nerve anatomy

A total of 30 healthy volunteers underwent magnetic resonance imaging (MRI) with T1 weighted (w.) 3D magnetization prepared rapid gradient echo (MP-RAGE), T2 w. 2D turbo spin echo (TSE) and T2* w. 3D constructive interference in steady state (CISS) sequences to evaluate the detectability of the optic, oculomotor, trochlear and abducens nerves. CISS yielded the best results for the trochlear and abducens nerve, MP-RAGE for the optic chiasm and tract. The optic and oculomotor nerves were very well detectable using both CISS and MP-RAGE without any statistically significant difference between the two.     

Imaging of neuropathies about the hip

Neuropathies about the hip may be cause of chronic pain and disability. In most cases, these conditions derive from mechanical or dynamic compression of a segment of a nerve within a narrow osteofibrous tunnel, an opening in a fibrous structure, or a passageway close to a ligament or a muscle. Although the evaluation of nerve disorders primarily relies on neurological examination and electrophysiology, diagnostic imaging is currently used as a complement to help define the site and aetiology of nerve compression and exclude other disease possibly underlying the patient’ symptoms. Diagnosis of entrapment neuropathies about the hip with US and MR imaging requires an in-depth knowledge of the normal imaging anatomy and awareness of the anatomic and pathologic factors that may predispose or cause a nerve injury. Accordingly, the aim of this article is to provide a comprehensive review of hip neuropathies with an emphasis on the relevant anatomy, aetiology, clinical presentation, and their imaging appearance. The lateral femoral cutaneous neuropathy (meiralgia paresthetica), femoral neuropathy, sciatic neuropathy, obturator neuropathy, superior and inferior gluteal neuropathies and pudendal neuropathy will be discussed.     

Clinical and imaging anatomy of the scalp

The purpose of this paper is to illustrate the clinical and imaging anatomy of the scalp. The territories of the vessels, lymphatics, and nerves together with the epicranial muscles of the galea are illustrated. The traditional cross-sectional anatomic layers are described and their gross anatomic boundaries are given. They are regrouped into 3 coverings that can be distinguished on normal and pathologic magnetic resonance (MR) and computed tomography (CT) imaging. These are the epidermis/dermis, the subcutaneous layer, and the galea/subgalea/periosteum complex. This information will provide a handy reference to help describe scalp lesions.     

MR imaging of the major nerves about the elbow: cadaveric study examining the effect of flexion and extension of the elbow and pronation and supination of the forearm

Magnetic resonance (MR) imaging provides useful information in the evaluation of peripheral nerves. Recent advances in MR imaging allow for detailed depiction of the soft tissue structures of the elbow joint. Three major nerves are present about the elbow. Six cadaveric elbows were imaged to depict the normal anatomy of these nerves and to determine the best plane and position of the elbow for optimal visualization of each nerve. Axial images of the elbow in full extension with the forearm in supination allow identification of all major nerves. Axial images with the elbow in full flexion allow accurate assessment of the cubital tunnel and the ulner nerve. Axial images of the elbow in full extension with the forearm in pronation are helpful for assessment of the median and radial nerves in the forearm.     

Magnetic resonance imaging of the pelvis: prostate and urinary bladder

Magnetic resonance imaging has opened up a new horizon in the evaluation of the male pelvis. Its direct multiplanar imaging and display of the unique tissue contrast allows for the demonstration of prostate anatomy. Prostatic disease, even when confined to the gland, is easily depicted. However, one cannot distinguish benign from malignant processes. In a patient with a known prostatic neoplasm, magnetic resonance is useful as a staging modality. Accuracy in the staging of prostatic malignancies by MRI surpasses that of ultrasound or CT. In the evaluation of the urinary bladder, the greatest advantage of magnetic resonance is its ability to differentiate between a normal bladder, and other pathologic conditions affecting the bladder, including inflammatory, congestive and neoplastic processes. In the evaluation of bladder carcinoma, magnetic resonance is useful as a staging modality. Clinical application of magnetic resonance is just beginning and therefore, the full potential of the modality has yet to be explored.     

Magnetic resonance imaging of the pelvis: Prostate and urinary bladder

Magnetic resonance imaging has opened up a new horizon in the evaluation of the male pelvis. Its direct multiplanar imaging and display of the unique tissue contrast allows for the demonstration of prostate anatomy. Prostatic disease, even when confined to the gland, is easily depicted. However, one cannot distinguish benign from malignant processes. In a patient with a known prostatic neoplasm, magnetic resonance is useful as a staging modality. Accuracy in the staging of prostatic malignancies by MRI surpasses that of ultrasound or CT. In the evaluation of the urinary bladder, the greatest advantage of magnetic resonance is its ability to differentiate between a normal bladder, and other pathologic conditions affecting the bladder, including inflammatory, congestive and neoplastic processes. In the evaluation of bladder carcinoma, magnetic resonance is useful as a staging modality. Clinical application of magnetic resonance is just beginning and therefore, the full potential of the modality has yet to be explored.     

Magnetic resonance imaging of the elbow

Elbow pain is frequently encountered in clinical practice and can result in significant morbidity, particularly in athletes. Magnetic resonance imaging (MRI) is an excellent diagnostic imaging tool for the evaluation of soft tissue and osteochondral pathology around the elbow. Recent advances in magnetic field strength and coil design have lead to improved spatial resolution and superior soft tissue contrast, making it ideal for visualization of complex joint anatomy. This article describes the normal imaging appearances of anatomy around the elbow and reviews commonly occurring ligamentous, myotendinous, neural, and bursal pathology around the elbow. J. Magn. Reson. Imaging 2010;31:1036–1053. © 2010 Wiley‐Liss, Inc.     

Magnetic Resonance Imaging of the Temporal Lobe: Normal Anatomy and Diseases

Objective

This pictorial essay will review the magnetic resonance imaging anatomy of the temporal lobes and describe the major pathologic processes of this complex area.

Conclusions

Magnetic resonance imaging is an essential tool in the investigation of a patient with suspected temporal lobe pathology. Various conditions may affect this anatomic region, and, therefore, classification of imaging findings into specific groups may help provide a more focused differential diagnosis.