Cerebrospinal fluid pleocytosis level as a diagnostic predictor? A cross-sectional study

Area of Science:

• Neurology
• Infectious Diseases
• Clinical Diagnostics

Background:

• Cerebrospinal fluid (CSF) analysis, including leukocyte quantification and differential counts, is standard for suspected neuroinfections.
• Non-infectious conditions can also present with low leukocyte counts (0-1000 cells/ml) in CSF.
• The diagnostic spectrum of pleocytosis in unselected adult patients requires further assessment.

Purpose of the Study:

• To evaluate the diagnostic diversity of cerebrospinal fluid (CSF) pleocytosis in unselected adult patients.
• To differentiate between infectious and non-infectious causes of elevated CSF leukocytes.

Main Methods:

• Retrospective analysis of CSF samples from adult patients (≥15 years) admitted to a university hospital over two years (2008-2009).
• Data integrated from patient administrative systems, charts, and laboratory results.
• Inclusion of 5390 CSF samples from 3290 patients.

Main Results:

• Pleocytosis (>5 leukocytes/μl) was observed in 262 patients.
• Central nervous system (CNS) infections accounted for 40.5% of cases, non-infectious neurological diseases for 30.2%, malignancy for 8.8%, and infections outside CNS for 7.6%.
• Patients with CNS infections showed significantly higher mean CSF leukocytes (1135 cells/μl, p < 0.0001).

Conclusions:

• Pleocytosis in CSF can be indicative of CNS infection, non-infectious neurological disease, malignancy, or infection outside the CNS.
• CSF leukocyte counts >100/μl predominantly suggest CNS infection.
• Lower CSF leukocyte counts (<50/μl) broaden the differential diagnosis, frequently involving non-infectious neurological diseases such as seizures.