1.
（1）细菌感染后脑脊液压力增高，外观呈混浊或脓样，白细胞总数显著升高，多核细胞为主，蛋白质显著增高，糖和氯化物明显降低。
（2）病毒感染后脑脊液正常或轻度增高，重症可明显增高。外观无色透明或黄变（出血），细胞数正常或轻中度增加，淋巴细胞为主，蛋白质正常或轻中度增高，糖和氯化物正常。
（3）真菌感染后脑脊液压力明显增高，外观透明，白细胞总数升高，淋巴细胞为主。蛋白质增高，糖明显降低，氯化物可正常。
2.
（1）任何年龄或季节均可发病，以40岁以上成人多见。原发感染潜伏期2-21天，前驱症状有发热、全身不适、肌痛、嗜睡、腹泻等。多急性起病, 约1/4患者有口唇疱疹史，病后体温可高达38.4~40.0℃，病程数日至1-2个月 。
（2）临床常见症状头痛、发热、呕吐、颈强直、局灶性神经功能缺损，有意识障碍、精神行为异常及认知障碍，约1/3患者出现全身性或部分性癫痫发作。相对特异性症状是额颞叶功能障碍相关的神经系统表现。
（3）病情常在数日内快速进展，多数患者有意识障碍，表现为意识模糊或谵妄，随病情加重可出现嗜睡、昏睡、昏迷或去皮质状态。重症患者可因广泛脑实质坏死和脑水肿引起颅内压增高，甚至脑疝形成而死亡。
1.
(1) After bacterial infection, the pressure of the cerebrospinal fluid is increased, the appearance is cloudy or pus-like, the total number of white blood cells is significantly increased, mainly multinucleated cells, the protein is significantly increased, and the sugar and chloride are significantly reduced.
(2) After virus infection, the cerebrospinal fluid is normal or slightly increased, and severely ill may increase significantly. The appearance is colorless and transparent or yellowing (bleeding), the number of cells is normal or slightly to moderately increased, lymphocytes are predominant, protein is normal or slightly to moderately increased, and sugar and chloride are normal.
(3) After fungal infection, the pressure of cerebrospinal fluid is obviously increased, the appearance is transparent, the total number of white blood cells is increased, and lymphocytes are predominant. The protein is increased, the sugar is obviously reduced, and the chloride can be normal.
2.
(1) The disease can occur at any age or season, and it is more common in adults over 40. The incubation period of primary infection is 2-21 days, and the prodromal symptoms include fever, general malaise, myalgia, lethargy, diarrhea, etc. The onset is often acute. About 1/4 of the patients have a history of herpes labialis. After the illness, the body temperature can be as high as 38.4~40.0℃, and the course of the disease can range from several days to 1-2 months.
(2) Common clinical symptoms include headache, fever, vomiting, neck stiffness, focal neurological deficits, disturbances in consciousness, abnormal mental behavior, and cognitive impairment. About 1/3 of patients have generalized or partial seizures. Relatively specific symptoms are neurological manifestations related to frontotemporal dysfunction.
(3) The condition often progresses rapidly within a few days. Most patients have disturbances in consciousness, manifested as confusion or delirium. As the condition worsens, drowsiness, lethargy, coma or decortex may appear. Critically ill patients can die due to increased intracranial pressure caused by extensive brain parenchymal necrosis and brain edema, and even brain herniation.