阴离子间隙(Anion—Gap),简称AG,血清中AG 对酸碱平衡紊乱的诊断意义已被很多临床医师重视。脑脊液中AG 在神经系统感染性疾病中的诊断意义尚未引起应有的重视。细菌性脑膜炎的脑脊液常规化验结果有时呈非典型变化,细菌学检查也常呈阴性,与病毒性脑炎不易鉴别。在有条件的医院可测定脑脊液的乳酸盐、乳酸脱氢酶、C 反应蛋白、免疫球蛋白,还可做对流免疫电泳、免疫荧光检查来检测相应微生物的抗原及鲎蛛溶解物试验等,对鉴别诊断很有意义,而现在大多数医院还不能做这些检测,却能做Na~+、K~+、Cl~-、TCO_2的测定,对脑脊液做这些 Anion-Gap, referred to as AG, serum AG in the diagnosis of acid-base disorders have been the significance of many clinicians attention. The diagnostic value of AG in cerebrospinal fluid in nervous system infectious diseases has not been given due attention. Bacterial meningitis cerebrospinal fluid routine laboratory results sometimes showed atypical changes, bacteriological tests are often negative, and viral encephalitis is not easy to identify. Cerebrospinal fluid lactate, lactate dehydrogenase, C-reactive protein, immunoglobulin can be determined in conditional hospitals, but also do convection immuno-electrophoresis, immunofluorescence test to detect the antigen of the corresponding microorganisms, It is very meaningful for differential diagnosis, but most hospitals can not do these tests now, but can do Na ~ +, K ~ +, Cl ~ -, TCO_2 determination of cerebrospinal fluid