The role of lumbar puncture in the evaluation of dementia: the Durham Veterans Administration/Duke University Study.

The use of lumbar puncture (LP) and cerebrospinal fluid (CSF) analysis in the routine, initial evaluation of patients with dementia continues to be questioned. This is especially true in the investigation of infectious causes of dementia. To explore this question further, the authors performed a retrospective analysis of 672 hospitalized patients specifically evaluated for dementia. LP and CSF analysis were performed on 402 patients (60 per cent); routine bacteriologic, acid-fast, and fungal cultures were also obtained for 333 of these patients. Most patients were white (64 per cent) and male (63 per cent), their mean age being 66 +/- 11 years. Four patients were diagnosed as having meningitis--two with Cryptococcus neoformans, one with apparent Mycobacterium tuberculosis, and one with coagulase-positive Staphylococcus aureus. These patients were characterized by a subacute change in mental status, fever or meningismus, and CSF pleocytosis with abnormal CSF chemistries. None of the patients were found to have newly diagnosed neurosyphilis. The authors conclude that LP and CSF analysis should not be part of the routine evaluation of patients with dementia and should be performed only in the presence of such indications as a subacute duration of dementia, fever, and signs of meningeal irritation.