5578 LPs were performed on 4549 patients, representing 4961 clinical episodes. Of these, 2293 had
normal CSF and 931 had minor abnormalities and no aetiology identified. Of the remaining 1737, microbiological
diagnoses were obtained in 820 (47%). Cryptococcus accounted for 63% (514) of microbiological diagnoses, TB for
28% (227), bacterial meningitis for 8% (68). Of the remaining 917 who had marked abnormalities, the majority
(59%) had a sterile lymphocytic CSF. Of note 16% (81) patients with confirmed Cryptococcus, 5% (12) with TB and
4% (3) with bacterial meningitis had normal CSF cell-counts and biochemistry.