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。     

Vascular compression of cranial nerves. I. History of the microvascular decompression operation

Abstract

The development of the microvascular decompression (MVO) operation is reviewed. It is stressed that a few innovative neurosurgeons discovered the role of vascular compression of cranial nerves V and VII in trigeminal neuralgia (TGN) and hemifacial spasm (HFS) and developed an operation, later to be known as the 0VO operation. While the understanding of the pathophysiology. of these disorders has improvedl the surgIcal procedure has undergone little change since Gardner described the operation about 1960. [Neural Res 1998; 20: 727–731]     

Vascular compression, hemifacial spasm, and multiple cranial neuropathy

Hemifacial spasm is usually an isolated symptom resulting from facial nerve root compression. Three patients had, in addition, tinnitus, hearing loss, facial sensory loss, diminished gag reflex, dysphagia, and dysarthria. Acoustic reflexes were abnormal, and facial nerve conduction studies showed evidence of ephaptic transmission and ectopic excitation. Brain CT and metrizamide cisternography were normal. Surgical exploration showed compression of cranial nerve roots by posterior inferior cerebellar artery branches. After decompression, symptoms abated, and electrical signs of hemifacial spasm disappeared. Vascular compression of nerve roots in the cerebellopontine recess may cause multiple cranial neuropathy.     

Electrodiagnosis of the cranial nerves

Isolated facial weakness suggests either a contralateral hemispheric lesion or a disease of the facial nerve per se. The presence of sensory symptoms usually indicates a central facial weakness, which characteristically involves the lower part of the face. In contrast, the absence of sensory disturbances suggests a peripheral nerve lesion, some system diseases such as amyotrophic lateral sclerosis, or a stroke sparing the sensory cortex. Sporadic cases of Bell's palsy rank the first in incidence. Although its exact etiology remains unknown, accumulating evidence suggests reactivation of herpes simplex virus type I. A facial palsy that develops in patients with diabetes mellitus tends to show a more severe involvement with substantial denervation. Acoustic neuroma, strategically located at the cerebellopontine angle, may compress the facial nerve. Peripheral facial palsy may herald other symptoms of multiple sclerosis in young adults. Serial electrodiagnostic studies help delineate the course of the illness. The amplitude of the direct response elicited by stimulation of the facial nerve after the fourth to fifth day of onset serves as the best means predicting the eventual outcome of recovery. Blink reflex studies usually show an absent or delayed R1, implicating the central reflex arc, which includes the intrapontine portion of the facial nerve.     

Ganglioside composition of the human cranial nerves, with special reference to pathophysiology of Miller Fisher syndrome

Total ganglioside fractions from the human cranial nerves purified on a Phenyl Sepharose column, were given mild alkaline treatment, after which their composition and amounts of lipid-bound sialic acid were determined by HPTLC-densitometry with resorcinol as the coloring reagent. The total amounts of lipid-bound sialic acid were 156.5 ng/mg of wet tissue in the Ist cranial nerve (olfactory tract) and 131.9 ng/mg in the IInd nerve, greater than the amounts in the other nerves (99.1–120.0 ng/mg). The Ist, IInd, and VIIIth nerves had GM4, but not LM1. It may reflect their histological feature of the central nervous system. The IIIrd, IVth, and VIth nerves, as well as the IInd, had significantly higher percentages of GQ1b (11.6–13.2%) than the other nerves (5.2–8.4%). The high proportion of GQ1b specific to these three cranial nerves involved in the ocular movement lends support to the role of serum anti-GQ1b antibody in the pathogenetic mechanisms of ophthalmoplegia in Miller Fisher syndrome and Guillain-Barré syndrome.     

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.     

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.     

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.     

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.     

Vascular complications of cranial radiation

Objectives Cerebral vascular disease has been reported as a long-term complication of cranial radiotherapy. The purpose of this study was to examine the frequency and risk factors associated with development of cerebral vascular disease in children after cranial radiation.Materials and methods A retrospective chart review of all cancer patients treated between 1985 and 2003 who were under the age of 18 years at the time of initial radiotherapy was performed. Variables examined include diagnosis and site of malignancy, age at the time of radiotherapy, sex, total radiation dosage, number of fractions, duration, and whether the patient had proven cerebral vascular event.Results Two hundred and forty-four patients met the study criteria. One hundred and 13 cases involved tumors of the central nervous system. The remaining patients had systemic neoplastic disease. Post radiation cerebral vascular disease occurred in 11 (5%) patients, and all but one patient had a tumor involving the central nervous system (mainly in the posterior fossa and supratentorial midline).Conclusion There is an increased risk of cerebral vascular disease after radiation therapy in childhood, especially in children who received high dose radiation at the posterior fossa and supratentorial axial region.     

海绵窦内颅神经血液供应显微外科解剖研究

目的 为减少海绵窦显微外科手术时损伤海绵窦内颅神经血供而研究这些颅神经的血液供应解剖。方法 50具成人尸体海绵窦标本,在解剖显微镜下解剖和分析。结果（１）９０侧（占90％）的标本示动眼神经由颈内动脉的下外侧动脉分支供血;（2）滑车神经近段有74例（占74％）的标本示其接受下外侧动脉的分支供血,有26例（占26％）标本示其接受脑膜垂体动脉分支天幕动脉的供血,滑车神经远段主要由下外侧动脉的分支供血;（3）在Dorellos管区域,外展神经近段接受脑膜背侧动脉的血供,中段及远段由下外侧动脉的分支供血;（4）三叉神经的眼支和上颌支由下外侧动脉的分支供血,三叉神经节的内侧部由下外侧动脉和天幕动脉的分支供血,中部由下外侧动脉的分支供血,外侧部由下外侧动脉的分支或由脑膜中动脉供血。结论 下外侧动脉在海绵窦内颅神经供血中起重要作用。术中我们应保护这些血供,就可减少术后颅神经功能障碍。     

Gd-DTPA enhancement of cranial nerves on MR imaging. Neoplastic lesions

This study describes a radiological finding - enhancement of cranial nerves and correlates patients' clinical findings and outcome. Seven patients with enhancement of cranial nerves on postcontrast MR were retrospectively reviewed. Cranial nerves having contrast enhancement were optic, oculomotor, trigeminal, facial, acoustic, glossopharyngeal, vagus and accessory nerves. The patients' underlying diseases were malignant lymphoma (3), leukemia (1 patient) and metastatic tumor (2 lung, 1 rectum cancer). Most of the cases (4 out of 7) developed parenchymatous lesion later. Seven patients had CSF cytology study, positive in 3 cases, negative in 4 cases at first spinal tap. In 1 case (case 5) of negative cytology, elevated CEA (carcinogen antibody) was noted. In 2 cases, initial symptoms were sudden hearing loss. Autopsy was done for 1 case of metastatic tumor involving cranial nerves. Contrast MR is a useful examination for depicting cranial nerve involvement with neoplastic change.     

Recurrent multiple paralysis of cranial nerves. Gougerot-Sj?gren syndrome

A 53 year-old woman presented with 6 episodes of recurrent cranial nerve palsies over seven years, each episode lasting several weeks. She had three episodes of diplopia, one of difficulty with swallowing, a left facial paralysis and two episodes of trigeminal sensory neuropathy. Sj?gren's syndrome was diagnosed when the patient developed dryness of the eyes and mouth, 7 years after the first episode. The diagnosis was proved by biopsy of the accessory salivary glands, the presence of a hypergammaglobulinaemia and anti-tissue antibodies.     

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。