The lumbar puncture. Patterns of use in clinical practice.

The records of 195 patients who had undergone lumbar puncture (LP) before or after the introduction of computerized axial tomography (CT) were reviewed. Twenty percent of the patients had potentially important spinal fluid abnormalities. The LP changed the diagnosis in 10% of the patients and changed therapy in 10% of the patients. It contributed to the patient's care in 32% of the patients prior to the introduction of the CT and in 48% of the patients after the introduction of the CT (p less than 0.05). Introduction of the CT was associated with a 35% decrease in the frequency of the LP (p less than 0.05). We found that fungal and AFB cultures did not appear to be indicated in most patients. We conclude that use of the LP has improved since the introduction of the CT. Further improvement is still possible, however.