中樞神經(jīng)系統(tǒng)感染-1ppt課件

1、VIRAL MENINGITIS &ENCEPHALITIS Viral meningitis refers to meningitis caused by a viral infection. Children and young adults are frequently affected. Viral meningitis is most often caused by enteric 腸道的viruses Viral encephalitis by childhood exanthems皮疹, arthropod-borne節(jié)肢動物agents蟲媒性病原體, and herpe

2、s simplex type 1.Cause最常見最常見柯薩奇病毒柯薩奇病毒ECHO病毒病毒腸道病毒腸道病毒其次其次流行性腮腺炎流行性腮腺炎單純皰疹病毒單純皰疹病毒腺病毒腺病毒PathologyViral infections can affect the central nervous system in three ways血源性播散 ：hematogenous dissemination of a systemic viral infection(eg, arthropod-borne viruses蟲媒性病毒); 軸突傳播：neuronal spread of the virus by

3、 axonal transport (eg, herpes simplex, rabies狂犬病病毒); 自身免疫性感染后脫髓鞘：autoimmune postinfections demyelination脫髓鞘 (eg, varicella水痘病毒, influenza). Pathologic changes in viral meningitis consist of an inflammatory meningeal reaction mediated by lymphocytes. 病毒性腦膜炎的病理改變是由淋巴細(xì)胞介導(dǎo)的病毒性腦膜炎的病理改變是由淋巴細(xì)胞介導(dǎo)的炎性腦膜反應(yīng)。炎性腦

4、膜反應(yīng)。 Encephalitis is characterized by perivascular cuffing, lymphocytic infiltration, and microglial proliferation mainly involving subcortical gray matter regions. Internuclear or intracytoplasmic inclusions are often seen. 病毒性腦炎的病理改變特點是血管周圍套袖樣改變、淋巴細(xì)胞浸潤，以及累及皮層下灰質(zhì)的小膠質(zhì)增生，并經(jīng)?？梢姷胶藵{或細(xì)胞漿內(nèi)包涵體。Clinical fin

5、dings-symptoms and signs Clinical manifestations include fever, headache, neck stiffness, photophobia畏光, pain with eye movement, and mild impairment of consciousness. Patients usually do not appear as ill as those with bacterial meningitis. Systemic viral infection may cause skin rash, pharyngitis咽炎

6、, lymphadenopathy淋巴結(jié)病, pleuritis胸膜炎, carditis心肌炎, jaundice黃疸, organomegaly器官腫大, diarrhea腹瀉, or orchitis睪丸炎, and these findings may suggest a particular etiologic agent病原體. Because viral encephalitis involves the brain directly, marked alterations of consciousness, seizures, and focal neurologic sign

7、s can occur. When signs of meningeal irritation腦膜刺激征and brain dysfunction coexist共存, the condition is termed meningoencephalitis腦膜腦炎. Laboratory findingsCSF analysis is the most important laboratory test. CSF pressure is normal or increaseda lymphocytic or monocytic pleocytosis腦脊液細(xì)胞數(shù)增多 is present, w

8、ith cell counts usually less than 1000/ml. (higher counts can be seen in lymphocytic choriomeningitis脈絡(luò)叢腦膜炎o(hù)r herpes simplex encephalitis.) A polymorphonuclear多形核白細(xì)胞 pleocytosis can occur early in viral meningitis, while red blood cells may be seen with herpes simplex encephalitis. Protein is normal

9、 or slightly increased (usually 80120mg/dL). Glucose is usually normal, but may be decreased in mumps腮腺炎, herpes zoster帶狀皰疹, or herpes simplex encephalitis. Grams stain and bacterial, fungal, and acid-fast bacillius(AFB) cultures are negative. Oligoclonal bands寡克隆區(qū)帶and CSF protein electrophoresis電泳a

10、bnormalities may be present. An etiologic diagnosis can often be made by virus isolation, polymerase chain reaction, or acute- and convalescent phase恢復(fù)期CSF antibody titers抗體滴度. Blood counts may show a normal white cell count, leukopenia白血球減少癥, or mild leukocytosis白細(xì)胞增多. Serum amylase血清淀粉酶is frequent

11、ly elevated in mumps 腮腺炎; abnormal liver function tests are associated with both hepatitis viruses肝炎病毒and infectious mononucleosis單核細(xì)胞增多癥. The EEG is diffusely slow, especially if there is direct cerebral involvement.DiagnosisDifferential diagnosis The differential diagnosis of meningitis with monon

12、uclear cell pleocytosis includes partially treated bacterial meningitis治療不徹底的細(xì)菌性腦膜炎 as well as syphilitic梅毒的, tuberculous結(jié)核性的, fungal, parasitic寄生物的, neoplastic腫瘤的, and other meningitides腦(脊)膜炎. Evidence of systemic viral infection and CSF wet mounts, stained smears, cultures, and cytologic examinat

13、ion細(xì)胞學(xué)檢查can distinguish among these possibilities. When presumed early viral meningitis is associated with a polymorphonuclear多形核白細(xì)胞pleocytosis of less than 1000 white blood cells/mL and normal CSF glucose, one of two strategies can be used. The paitent can be treated for bacterial meningitis until

14、the results of CSF cultures are known;Treatment can be withheld and lumbar puncture腰椎穿刺術(shù) repeated in 612 hours. If the meningitis is viral in origin, the second sample should show a mononuclear cell pleocytosis. A disorder that may be clinically indistinguishable from viral encephalitis is the immun

15、e-mediated encephalomyelitis that may follow viral infections such as influenza, measles麻疹, or chickenpox水痘. Progressive neurologic disfunction typically begins a few days after the viral illness, but can also occur either simultaneously同時發(fā)生 or up to several weeks later. Neurologic abnormalities res

16、ult from perivenous 靜脈周圍的demyelination脫髓鞘, with often severely affects the brainstem. The CSF shows a lymphocytic pleocytosis腦脊液細(xì)胞數(shù)增多, usually with cell counts of 50150/mL, and mild protein elevation.Treatment Except for herpes simplex encephalitis, which is discussed separately no specific therapy

17、for viral meningitis and encephalitis is available. Corticosteroids are of no proven benefit except in immune-mediated postinfectious syndromes. Headache and fever can be treated with acetaminophen醋氨酚, but aspirin should be avoided, especially in children and young adults, because of its association

18、 with Reyes syndrome. Seizures usually respond to phenytoin 苯妥英鈉or phenobarbital苯巴比妥. Supportive measures in comatose昏睡的patients include mechanical ventilation and intravenous or nasogastric feeding鼻飼.Prognosis Symptoms of viral meningitis usually resolve spontaneously within 2 weeks regardless of t

19、he causative agent, although residual deficits后遺癥may be seen. The outcome of viral encephalitis varies with the specific virus -for example, herpes simplex virus infections are associated with severe morbidity and high mortality rates. Mortality rates as high as 20% have also been reported in immune

20、-mediated encephalomyelitis腦脊髓炎following measles麻疹 infections. Herpes simplex virus (HSV) encephalitis HSV is the most common cause of sporadic散發(fā)的散發(fā)的 fatal encephalitis in the United States. About two-thirds of cases patients over 40 years of age. Primary herpes infections most often present as stom

21、atitis口炎口炎( HSV type 1) or a venereally 性交性交的的transmitted genital生殖器生殖器eruption出疹出疹 (HSV tpye 2). The virus migrates along nerve axons軸突to sensory ganglia神經(jīng)節(jié), where it persists in a latent form and may be subsequently reactivated. It is not clear whether HSV type 1 encephalitis, the most common type

22、 in adults, represents a primary infection or a reactivation of latent infection. Neonatal新生兒的HSV encephaltis usually results from acquisition獲得of type 2 virus during passage through the brith canal of a mother with active genital生殖器的lesions. Central nervous system involvement by HSV type 2 in adult

23、s usually causes meningitis, rather than encephalitis.Pathology HSV tpye 1 encephalitis is an acute, necrotizing引壞死的, asymmetric不對稱的hemorrhagic出血性的process with lymphocytic and plasma cell漿細(xì)胞reaction. Usually involves the medial temporal and inferior frontal lobes. Intranuclear inclusions核內(nèi)包涵體may be

24、seen in neurons神經(jīng)元and glia神經(jīng)膠質(zhì). Patients who recover康復(fù)期 may show cystic囊的necrosis壞死of the involved regions.嗜酸性嗜酸性Cowdry A型包涵體型包涵體Clinical Finding- A Symptoms and Signs The clinical syndrome may include headache, stiff neck, vomiting, behavioral disorders, memory loss, anosmia嗅覺喪失, aphasia, hemipares

25、is輕偏癱, and focal or generalized seizures. Active herpes labialis唇皰疹is seen occasionally, but does not reliably implicate HSV as the cause of encephalitis. HSV encephalitis is uaually rapidly progressive over several days and may result in coma or death. The most common sequelae 后遺癥 in patients who s

26、urvive are memory and behavior disturbances, reflecting the predilection 嗜好, 偏愛of HSV for limbic structures. Laboratory FindingsLaboratory Findings-CSF The CSF in HSV tpye 1 encephalitis most often shows increased pressure lymphocytic or mixed lymphocytic and polymorphonuclear多形核白細(xì)胞 pleocytosis( 501

27、00 white blood cells/mL) mild protein elevation, and normal glucose. Red blood cells, xanthochromia 黃變, and decreased glucose are seen in some cases. Laboratory Findings-VIRUS The virus generally cannot be isolated from the CSF, but viral DNA has been detected by the polymerase chain reaction聚合酶鏈反應(yīng)i

28、n some cases. HSV抗體檢定 ELASA是現(xiàn)今國際上通用的HSV抗體檢測方法。 本方法采用雙份血清和雙份腦脊液作HSV-1抗體的動態(tài)檢測。 診斷標(biāo)準(zhǔn)： 雙份CSF抗體有增高趨勢，滴度1:8以上； 雙份CSF抗體4倍以上升高； 血與CSF的抗體比值40。Laboratory Findings-EEG The EEG may show periodic周期的slow-wave complexes arising from one or both temporal lobesLaboratory Findings- CT MRI CT scans and MRI may show ab

29、normalities in one or both temporal lobes. These can extend to frontal or parietal regions頂區(qū)and are sometimes enhanced with the infusion注入of contrast material造影劑. However, imaging studies may also be normal.DiagnosisDifferential Diagnosis The symptoms and signs are not specific for herpes virus infe

30、ction. The greatest diagnostic difficulty is distinguishing between HSV encephalitis and brain abscess腦膿腫, and the tow disorders often cannot be differentiated on clinical grounds alone.brain abscessbrain abscess Other CNS infections and vasculitis血管炎can also mimic HSV encephalitis. Deginitive diagnosis can be made by biopsy of affected brain areas, with the choice of biopsy site guided by the EEG, CT, or MR