脱髓鞘幻灯2009医大课件.ppt
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1、Demyelinating disease of the CNS 中枢神经系统脱髓鞘疾病,Tianjin medical University General hospital Zhou Guang xi 天津医科大学总医院神经内科 周广喜 7702,Overview,Demyelinative disease is a group of diseases of brain and spinal cord in which destruction of myelin is a prominent feature. Myelin sheaths play importance role in p
2、rotecting and supporting for nervous fiber and transporting of material to neurons and maintaining of neurons ionic environment. The formation of myelin sheaths in both the central and peripheral nervous system follows a similar pattern. Central myelin is formed by an extension of membrane of the ol
3、igodendrocyte wrapping the axons, whereas peripheral myelin is formed by the extension of the Schwann cell membrane.,The commonest accepted the pathologic criteria of demyelinative disease in CNS:,1. Destruction of the myelin sheaths of nerve fibers; 2. Relative sparing of other elements of nervous
4、tissue, i.e. of axis cylinders, nerve cell, and supporting structure, and a relative lack of Wallerian, or secondary, degeneration off fiber tracts. 3. A particular distribution of lesions often is perivenous and primarily in white matter.,Classification of demyelination disease in CNS,Dysmyelinativ
5、e type (leukodystrophy) It results from failure to form normally constituted myelin, due to genetic enzymatic disorders, such as adrenoleukodystrophy (ADL), Globod leucodystrophy (Krabbe), Metachromatic leucodystrophy (MLD) Demyelinating type It is breakdown of normally constituted myelin.,Classific
6、ations of the demyelination disease,Multiple sclerosis 1. relapsing-remitting , RR 2. primary progressive, PP 3. secondary progressive, SP 4. progressive relapsing , PR Neuromyelitis optica (Devic) Diffuse cerebral sclerosis (Schilder) & concentric sclerosis of Balo Acute disseminated encephalomyeli
7、tis Central pontine myelinnolysis,Multiple sclerosis,Multiple sclerosis is the most common demyelinating disorder. It is a disease of the central white matter with “ lesions separated in time and space”. Generally, MS is characterized clinically by remitting - relapsing course. The disease usually o
8、ccurs in young adults. The peak age of onset is 20-40 and 95% patients occurs between 10-60 years. More females than males are affected.,Etiology and pathogenesis,1. Geographical influence: Populations residing between tropical and subtropical zones have a low risk of MS. All populations residing th
9、is latitudes in North America and Europe are higher risk. 2. Familial factors: It was found that almost 20% of index cases had an affected relative, again with the highest risk in siblings in a large population study in British. studies of twins histocompatibility antigens (HLAs) associations with H
10、LA- A3, B7, B18, and Dw2.,Etiology and pathogenesis,3. Infection and immunological mechanism: immunoregulatory defects may play a critical role in pathophysiology. autoimmunization of T lymphocytes against myelin basic protein caused several different viruses. (Johanson) cellular factors: T lymphocy
11、tes regulate humoral immune responses either as potentiators (T-helper cells) or as inhibitors (T-suppressor cells) A reduction in the blood of suppressor T lymphocytes was thought to characterize clinical relapse, or an increase in helper suppressor ratios, (CD4/CD8) dose appear to be associated wi
12、th increasing disability in patients of MS. Raised titres to many common viruses have been found in the serum and CSF of MS patients, but attempts to induce ms experimentally with viruses have been unsuccessful.,Pathology,The Area of demyelination are found in the white matter of the brain and spina
13、l cord. The lesions may vary in diameter from less than a millimeter to several centimeters. The periventricular localization is characteristic. Other favored structures are the optic nerves and chiasm, brainstem and cervical cord. There is myelin destruction with relative preservation of axons. An
14、inflammatory infiltrate containing mononuclear cells and lymphocytes is found. Interstitial oedema occurs in acute lesions.,Clinical feature,Early symptoms and signs Weakness or numbness, sometimes both, in one or more limbs is the initial symptom in about half the patients. Symptoms of tingling of
15、the extremities and tight band-like sensations around the trunk are commonly. Visual involvement most commonly takes the form of an acute optic neuritis with ocular pain. Typically, there is a central scotoma. In the acute stages, the disc is usually normal, but sometimes it is swollen (papillitis)
16、along with peripapillary haemorrhages.,Early symptoms and signs,Lhermitte sign was frequent occurrence in MS. Dull, aching pain in the low back is a common complaint. Sharp, burning, poorly localized, or characteristic lancinating-radicular pain, localized to limb or discrete part of the trunk, occu
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