Arterial vascularization of the cranial nerves

We discuss the arterial supply of the cranial nerves from their exit out of the brain stem to their exit from the skull base. Four distinct groups can be differentiated from an embryologic and phylogenetic standpoint. Understanding the arterial supply to the cranial nerves and the potential anastomoses is paramount in the endovascular treatment of dural AV shunts and highly vascularized tumors of the skull base to avoid neurologic deficits.     

Imaging of the lower cranial nerves

This article discusses the normal anatomy and pathologic entities that involve the lower cranial nerves. Normal anatomy is described and correlated with line diagrams and MR images. Distinct pathologic processes that involve the individual nerves along their various components are discussed. The imaging characteristics of these lesions are provided. Knowledge of the nuclear origins, the normal course of the cranial nerves, their func-tional components, and the imaging characteristics of pathologic lesions involving the nerves are important in any evaluation of cranial neuropathy.     

Denervation atrophy of motor cranial nerves

Muscles undergoing denervation demonstrate a variety of imaging appearances in the various stages. It is incumbent on the radiologist to be aware of these changes so as not to interpret these muscles as harboring a tumor or being involved by an inflammatory process. Knowledge of cranial nerve anatomy and the muscles they innervate enables identification of denervation patterns that could implicate more than one nerve and directs the search for the causative lesion.     

Visibility of cranial nerves at MRI

In order to assess the value of MRI in the depiction of intracranial nerves, we retrospectively reviewed 60 patients investigated over a 2-year period. The purposes of this study were: 1) to determine the score of MRI in detecting cranial nerves III to XII, and 2) to establish accurate landmarks for easy detection of these nerves. Cranial nerves III, V, VII and VIII are well seen (70 to 100%), very often on axial, sagittal and coronal sections. Nerves IX to XII are correctly studied only on axial planes (81 and 83%), but it is difficult to distinguish between the vagus nerve and the glossopharyngeal and spinal nerves. Due to their oblique direction and small size, nerves IV and VI are seldom visualized. The most important landmarks are the chiasma, the colliculi, Meckel's cavity, the internal auditory canal, the jugular foramen, the hypoglossal canal and the brainstem structures. We suggest the following scanning technique: short spin-echo sequences (TR 600 ms, TE 20 ms), 3 to 5 mm thick contiguous sections, 16 to 20 cm field of view with 4 or 2 excitations respectively, 256 x 256 matrix, and at least one acquisition plane (axial plane), but preferably two or three planes. MRI is a sensitive examination in the recognition of cranial nerves. It should be the first-step exploratory procedure in patients with cranial nerve pathology.     

Injury of the peripheral cranial nerves during carotid endarterectomy

The incidence of local nerve injury among 192 consecutive carotid endarterectomies in 162 patients between 1977-1983 was determined from review of the medical records. Two facial nerve, 5 hypoglossal nerve, and 2 vagus nerve injuries were discovered for a total incidence of 4.7%. Only the 2 facial nerve injuries failed to improve over 2 years. Followup ranged from 1 to 60 months in this group of patients. Careful attention to details of tissue dissection at surgery should lower the incidence of nerve injury during carotid endarterectomy.     

显微血管减压及神经松解手术治疗颅神经疾病1956例

目的 探讨显微血管减压及神经松解手术治疗颅神经疾病的方法及经验。方法 总结自1986至2005年12月以来局麻下共实施显微血管减压及神经松解手术治疗颅神经疾病1956例，其中三叉神经痛1465例，面肌痉挛428例，舌咽神经痛63例。患者平均年龄62．5岁，病史3至37年不等。介绍了显微血管减压及神经松解手术技巧及术中寻找责任血管及部分神经根切断的注意事项。结果 手术确定了1462例三叉神经痛、428例面肌痉挛和51例舌咽神经痛患者的压迫责任血管，并以teflon垫棉置于其间；对1876例局部蛛网膜和颅神经间的粘连行神经松解手术；对45例行神经根部分切断。手术效果满意。术后总有效率100％。31例复发，其中23例行二次手术治疗后病愈。结论 显微血管减压及神经松解手术是治疗颅神经疾病的有效手段，疗效确切。     

Multinevritis of cranial nerves following inhalation of toxins

Abstract

Cranial multineuropathy is an uncommon occurrence. We observed two cases of multinevritis of the cranial nerves which had many features in common: acute onset after toxic inhalation, occurrence of neuroparaxic block, and rapid resolution after corticosteroid therapy. We believe physicians should be aware that multinevritis of the cranial nerves may be related to acute exposure to toxic substances. Missing this diagnosis could lead to a delay in therapy.     

Multinevritis of cranial nerves following inhalation of toxins

Cranial multineuropathy is an uncommon occurrence. We observed two cases of multinevritis of the cranial nerves which had many features in common: acute onset after toxic inhalation, occurrence of neuroparaxic block, and rapid resolution after corticosteroid therapy. We believe physicians should be aware that multinevritis of the cranial nerves may be related to acute exposure to toxic substances. Missing this diagnosis could lead to a delay in therapy.     

脑神经疾患“血管压迫”病因的放射学诊断研究——磁共振断层成像脑血管造影术的应用

目的:探讨磁共振影像学对“压迫血管”病因诊断的可能性和特征。方法:采用稳定快速进动程序以提供脑实质、脑神经和后颅窝脑血管的高分辨率磁共振成像(MRI),即一种“白血”磁共振断层成像血管显影术(magnetic resonance tomographic angiography,MRTA)。分别检查11例三叉神经痛和21例面肌痉挛,同时10例行后颅窝探查及显微血管减压术(microvascular decompression,MVD),对照和评估MRTA的确诊率。结果:32例单侧三叉神经痛及面肌痉挛的MRTA中,确认患侧有“血管压迫”28例,无血管压迫4例。而正常侧仅见2例“血管接触或压迫”影像。1例三叉神经痛术中发现岩静脉为压迫血管,而MRTA提示无异常,因而未再行增强扫描、10例接受探查术发现有或无压迫血管,与MRTA诊断相符9例。结论:MRTA可作为脑神经疾患的”血管压迫”病因之术前诊断的一种特殊而可靠的检查方法,以便有的放矢地指导此类疾患的治疗。     

Endoscopic assistance in microvascular decompression of cranial nerves

Microvascular decompression (MVD) is an effective method for treatment of trigeminal neuralgia (TN), hemifacial spasm (HFS), glossopharyngeal neuralgia (GPN). The aim of this study was to assess the role of endoscopic assistance in MVD for the treatment of cranial neuropathies. Since 2009 till 2011 133 patients with cranial neuropathies were treated by MVD in Burdenko Neurosurgical Institute, Moscow. In 22 patients (11 patients with HFS, 10 patients with TN, 1 with GPN) endoscopic assistance was applied during the MVD. We used minimally invasive retrosigmoid approach in a unilateral position. Cerebellopontine angle was explored by 30-degree or 70-degree telescope to visualize the root entry zone of trigeminal, facial or glossopharyngeal nerves and to locate the neurovascular conflict. In 9 patients with HFS and in 1 patient with TN and in another patient with GPN endoscopy discovered offending vessels that were not visible through the microscope. In all cases endoscope was used to exclude another site of compression and to verify decompression and to identify position of teflon and offending vessel after MVD. Immediately after the surgery excellent outcome was observed in 10 patients with HFS (89%), one patient was reoperated 1.5 years after first operation with positive effect. Relief of pain in early postoperative period was observed in patients with TN and GPN. There were no major complications and postoperative mortality in our series. Endoscopic assistance is very effective and helpful technique in MVD of cranial nerves, especially in cases with HFS. In this study the use of the endoscope allowed to identify the site of compression and to confirm the position of teflon after MVD.     

Afferent interactions of cranial nerves involved in ingestion

Substantial behavioral evidence implicates visceral afferent activity in the regulation of feeding behavior. One mechanism often suggested for this influence involves visceral afferent activity interacting with oral or gustatory afferent activity. This brief review summarizes the anatomical and electrophysiological evidence that indicates that such interactions might in fact take place. The available evidence for interactions between visceral and gustatory afferent messages is far from convincing, but perhaps only because the issue has seldom been addressed. The most direct tests suggested by the hypothesis advanced remain to be carried out.     

Transient GABA immunoreactivity in cranial nerves of the chick embryo

The distribution and time course of gamma-aminobutyric acid (GABA) immunoreactivity was investigated in the cranium of the chick embryo from 2 to 16 days of incubation (E2-16). A fraction of nerve fibers transiently stains GABA-positive in all cranial motor nerves and in the vestibular nerve. Cranial motor nerves stain GABA-positive from E4 to E11, including neuromuscular junctions at E8-11; labeled fibers are most frequent in the motor trigeminal root (E6-9.5). Substantial GABA staining is present from E4 to E10 in a subpopulation (1-2%) of vestibular ganglion cells. Their peripheral processes are labeled in the vestibular endorgan, predominantly in the posterior crista. Some GABA-positive fibers are present in the olfactory nerve (after E5) and in the optic nerve (after E9.5); their immunoreactivity persists throughout the period investigated. Transient GABA immunoreactivity follows "pioneer" fiber outgrowth and coincides with the formation of early synaptic contacts. GABA-containing neurons may change their neuronal phenotype (loss of GABA expression) or they may be eliminated by embryological cell death. Periods of cell death were determined in cranial ganglia and motor nuclei by aggregations of pycnotic cells in the same embryonic material. The periods of embryonic cell death partly coincide with transient GABA immunoreactivity. The function(s) of transient GABA expression is unknown. Some lines of evidence suggest that GABA has neurotrophic functions in developing cranial nerves or their target tissue. In the developing neuromuscular junction, GABA may be involved in the regulation of acetylcholine receptors.