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1、VIRAL MENINGITIS 轴突传播：neuronal spread of the virus by axonal transport (eg, herpes simplex, rabies狂犬病病毒); 自身免疫性感染后脱髓鞘：autoimmune postinfections demyelination脱髓鞘 (eg, varicella水痘病毒, influenza).,Pathologic changes in viral meningitis consist of an inflammatory meningeal reaction mediated by lymphocyte
2、s.,病毒性脑膜炎的病理改变是由淋巴细胞介导的炎性脑膜反应。,Encephalitis is characterized by perivascular cuffing, lymphocytic infiltration, and microglial proliferation mainly involving subcortical gray matter regions. Internuclear or intracytoplasmic inclusions are often seen. 病毒性脑炎的病理改变特点是血管周围套袖样改变、淋巴细胞浸润，以及累及皮层下灰质的小胶质增生，并经常
3、可见到核浆或细胞浆内包涵体。,Clinical findings-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 cau
4、se skin rash, pharyngitis咽炎, lymphadenopathy淋巴结病, pleuritis胸膜炎, carditis心肌炎, jaundice黄疸, organomegaly器官肿大, diarrhea腹泻, or orchitis睾丸炎, and these findings may suggest a particular etiologic agent病原体.,Because viral encephalitis involves the brain directly, marked alterations of consciousness, seizures
5、, and focal neurologic signs can occur. When signs of meningeal irritation脑膜刺激征and brain dysfunction coexist共存, the condition is termed meningoencephalitis脑膜脑炎.,Laboratory findings,CSF analysis is the most important laboratory test. CSF pressure is normal or increased a lymphocytic or monocytic pleo
6、cytosis脑脊液细胞数增多 is present, with cell counts usually less than 1000/ml. (higher counts can be seen in lymphocytic choriomeningitis脉络丛脑膜炎or herpes simplex encephalitis.) A polymorphonuclear多形核白细胞 pleocytosis can occur early in viral meningitis, while red blood cells may be seen with herpes simplex en
7、cephalitis.,Protein is normal or slightly increased (usually 80120mg/dL). Glucose is usually normal, but may be decreased in mumps腮腺炎, herpes zoster带状疱疹, or herpes simplex encephalitis. Grams stain and bacterial, fungal, and acid-fast bacillius(AFB) cultures are negative. Oligoclonal bands寡克隆区带and C
8、SF protein electrophoresis电泳abnormalities may be present. An etiologic diagnosis can often be made by virus isolation, polymerase chain reaction, or acute- and convalescent phase恢复期CSF antibody titers抗体滴度.,Blood counts may show a normal white cell count, leukopenia白血球减少症, or mild leukocytosis白细胞增多.
9、Serum amylase血清淀粉酶is frequently elevated in mumps 腮腺炎; abnormal liver function tests are associated with both hepatitis viruses肝炎病毒and infectious mononucleosis单核细胞增多症.,The EEG is diffusely slow, especially if there is direct cerebral involvement.,Diagnosis,Differential diagnosis,The differential dia
10、gnosis of meningitis with mononuclear cell pleocytosis includes partially treated bacterial meningitis治疗不彻底的细菌性脑膜炎 as well as syphilitic梅毒的, tuberculous结核性的, fungal, parasitic寄生物的, neoplastic肿瘤的, and other meningitides脑(脊)膜炎.,Evidence of systemic viral infection and CSF wet mounts, stained smears, c
11、ultures, and cytologic examination细胞学检查can distinguish among these possibilities. When presumed early viral meningitis is associated with a polymorphonuclear多形核白细胞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
12、for bacterial meningitis until the results of CSF cultures are known; Treatment can be withheld and lumbar puncture腰椎穿刺术 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
13、 viral encephalitis is the immune-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同时发生 or up to several weeks lat
14、er.,Neurologic abnormalities result from perivenous 静脉周围的demyelination脱髓鞘, with often severely affects the brainstem. The CSF shows a lymphocytic pleocytosis脑脊液细胞数增多, usually with cell counts of 50150/mL, and mild protein elevation.,Treatment,Except for herpes simplex encephalitis, which is discusse
15、d separately no specific therapy 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 a
16、dults, because of its association with Reyes syndrome. Seizures usually respond to phenytoin 苯妥英钠or phenobarbital苯巴比妥. Supportive measures in comatose昏睡的patients include mechanical ventilation and intravenous or nasogastric feeding鼻饲.,Prognosis,Symptoms of viral meningitis usually resolve spontaneously within 2 weeks regardless of the causative agent, although residual deficits后遗症may be seen. The outcome of viral encephalitis varies with the specific virus -for example, herpes simplex
