From the Guidelines
Elevated white blood cells in cerebrospinal fluid (CSF) are primarily caused by infections of the central nervous system, with bacterial meningitis typically producing the highest counts (>1000 cells/μL) and viral meningitis showing moderate elevation (50-500 cells/μL). The causes of elevated white blood cells in CSF can be categorized into infectious and non-infectious etiologies. Infectious causes include:
- Bacterial meningitis, which typically presents with high white blood cell counts (>1000 cells/μL) and neutrophil predominance 1
- Viral meningitis, which usually shows moderate elevation (50-500 cells/μL) with lymphocyte predominance 1
- Fungal and tuberculous meningitis, which generally cause moderate elevation with lymphocytic predominance 1 Non-infectious causes include:
- Subarachnoid hemorrhage, which introduces red and white blood cells into CSF
- Multiple sclerosis and other autoimmune conditions like neurosarcoidosis and CNS vasculitis
- Certain medications and treatments like NSAIDs, antibiotics, or intrathecal chemotherapy
- Malignancies such as leukemia, lymphoma, or metastatic cancer infiltrating the meninges The pattern of cell elevation (neutrophilic vs. lymphocytic), protein levels, glucose concentration, and other CSF parameters help differentiate between these causes 1. Prompt evaluation with appropriate cultures, PCR testing, cytology, and imaging is essential for accurate diagnosis and treatment, as some causes like bacterial meningitis require immediate antibiotic therapy 1.
Some key considerations for interpreting CSF results include:
- A traumatic lumbar puncture can affect the results by falsely elevating the white cells due to excessive red cells 1
- The presence of red blood cells in the CSF can indicate a hemorrhagic process, such as subarachnoid hemorrhage or HSV encephalitis 1
- The CSF lactate level can help distinguish between bacterial and viral meningitis, with a level of <2 mmol/l ruling out bacterial disease 1
- The presence of oligoclonal bands in the CSF can indicate a diagnosis of multiple sclerosis or other demyelinating diseases 1
From the Research
Causes of Elevated White Blood Cells in CSF
Elevated white blood cells in cerebrospinal fluid (CSF) can be caused by various conditions, including:
- Bacterial meningitis: Studies have shown that bacterial meningitis can cause elevated white blood cells in CSF, even in the absence of pleocytosis on lumbar puncture 2, 3.
- Viral meningitis: Viral meningitis is considered the main cause of lymphocyte meningitis, which is characterized by a predominance of lymphocytes in the CSF 4.
- Multiple sclerosis: Markedly elevated CSF white blood cells can occur in otherwise typical relapsing-remitting multiple sclerosis (RRMS) and are not always a red flag to an alternative diagnosis 5.
- Other conditions: Other conditions, such as immunocompromising conditions, sepsis, and miscellaneous infections, can also cause elevated white blood cells in CSF 6.
Characteristics of Elevated White Blood Cells in CSF
The characteristics of elevated white blood cells in CSF can vary depending on the underlying condition, including:
- Lymphocytic predominance: Lymphocytic predominance is often seen in viral meningitis and multiple sclerosis 4, 5.
- Elevated CSF protein: Elevated CSF protein levels can be seen in bacterial meningitis, particularly in severe pneumococcal meningitis 6.
- Presence of bacteria: The presence of bacteria in the CSF Gram stain can be an important diagnostic parameter in bacterial meningitis 6.
Diagnostic Considerations
Diagnostic considerations for elevated white blood cells in CSF include:
- CSF analysis: CSF analysis is essential to establish the diagnosis and to identify the etiological agent of lymphocytic meningitis 4.
- Blood cultures: Blood cultures can be an adjunct to CSF analysis in the diagnosis of bacterial meningitis 2, 3.
- Imaging studies: Imaging studies, such as MRI, can be helpful in diagnosing multiple sclerosis and other conditions that can cause elevated white blood cells in CSF 5.