1。The Management of Encephalitis: Clinical Practice Guidelines by the Infectious Diseases Society of America（IDSA）
Clinical Infectious Diseases 2008; 47:303–27
所有病人推荐行MRI检查。MRI of the brain should be performed in all patients, with CT used only if MRI is unavailable, unreliable, or cannot be performed。
所有病人推荐行EEG检查。Electroencephalography (EEG) is rarely helpful in establishing an etiology in patients with encephalitis, but it has a role in identifying patients with nonconvulsive seizure activity who are confused, obtunded, or comatose and should be performed in all patients with encephalitis (A-III).
所有脑炎病人应该行单纯疱疹病毒PCR检测。Herpes simplex PCR should be performed on all CSF specimens in patients with encephalitis (A-III).

水痘带状疱疹病毒脑炎推荐予阿昔洛韦治疗，更昔洛韦可以作为选择，联合使用激素可以考虑。Varicella-zoster virus: acyclovir is recommended (B-III); ganciclovir can be considered an alternative (C-III); adjunctive corticosteroids can be considered (C-III). 
EB病毒脑炎阿昔洛韦不被推荐，皮质激素可能有益，但必须衡量获益风险比。Epstein-Barr virus: acyclovir is not recommended; the use of corticosteroids may be beneficial (C-III), but the potential risks must be weighed against the benefits.

结核脑应该初始即予四联抗结核治疗，对于脑膜炎的病人应该加用地塞米松治疗。Mycobacterium tuberculosis: 4-drug antituberculous therapy should be initiated (A-III); adjunctive dexamethasone should be added in patients with meningitis (B-I).

32%–75%的病人仍难以确定病原。In many cases of encephalitis (32%–75%), however, the etiology remains unknown, despite extensive diagnostic evaluation.

在确定或可能的病例中，69%为病毒，20%为细菌，7%朊病毒，3%为为寄生虫，1% 为真菌。Of the confirmed or probable cases, 69% were viral, 20% were bacterial, 7% were prion related, 3% were parasitic, and 1% were fungal.

双侧颞叶受累是单疱的近似特征性表现，但这是后期的表现。超过90% 的单疱脑炎病人在MRI上有异常发现。bilateral temporal lobe involvement is nearly pathognomonic for herpes simplex encephalitis, but this is a late development. More than 90% of patients with herpes simplex encephalitis documented by CSF PCR will have abnormalities seen on MRI [53]. 
在虫媒病毒和东方马脑病毒的脑炎患者中，MRI上的特征性表现为丘脑、基底节、中脑T1像为混合信号或低信号，而T2及FLAIR 像为高信号。在肠道病毒71脑炎的患者中，T2及FLAIR 像脑干上可以发现局灶性高信号病变。In patients with encephalitis caused by flaviviruses and Eastern equine encephalitis virus, MRI may display a characteristic pattern of mixed intensity or hypodense lesions on T1-weighted images in the thalamus, basal ganglia, and midbrain; these lesions are hyperintense on T2 and fluid-attenuated inversion recovery (FLAIR) images. In patients with enterovirus 71 encephalitis, MRI may demonstrate hyperintense T2 and FLAIR lesions localized to the midbrain, pons, and medulla.

在＞80%的单疱脑炎患者中，存在颞部局部的周期性侧向癫痫样放电。这些典型的尖慢综合间隔2–3 s 发放，在起病后2-14天表现典型。脑干脑炎的脑电图常常表现的较轻，而与临床表现不一致；多表现为弥漫的慢波活动和间歇的节律发放。In ＞80% of patients with herpes simplex encephalitis, there is a temporal focus demonstrating periodic lateralizing epileptiform discharges [56]. These stereotypical sharp and slow wave complexes occur at intervals of 2–3 s and are typically seen on days 2-14 after symptom onset. The EEG abnormalities in brainstem encephalitis may be disproportionately mild, compared with the clinical state of the patient; diffuse slow wave activity and intermittent rhythmic activity have been described in these patients.

超过10%的单疱脑炎病人脑脊液完全正常。Up to 10% of patients with viral encephalitis can have completely normal CSF findings.

单疱脑炎病人预后不良的指标包括：年龄大于三十岁，GSC＜6，在发病后4天才开始阿昔洛韦的治疗；假如在起病4天内开始治疗致死率降到8%。(mortality at 18 months after treatment, 28%).In patients with herpes simplex encephalitis, predictors of an adverse outcome include age of the patient (＞30 years), level of consciousness (Glasgow coma score, ＜6), and duration of symptoms prior to starting acyclovir therapy (＞4 days) [88]; mortality decreased to 8% if therapy was initiated ＜4 days after onset of clinical symptoms.

在一项45例联合皮质激素和阿昔洛韦治疗单疱脑炎的非随机、回顾性研究中，观察到没有使用激素治疗的病人预后更差，但这些结果需要进一步确认。Use of adjunctive corticosteroids was assessed in one nonrandomized, retrospective study of 45 patients with herpes simplex encephalitis treated with acyclovir [94]. Although a worse outcome was observed in patients who were not treated with corticosteroids, these results need to be confirmed before this adjunctive treatment can be recommended.