Cerebrospinal Fluid Profile After Stroke: Understanding WBC Elevation
Yes, cerebrospinal fluid (CSF) profiles can show raised white blood cell (WBC) counts post-stroke, though this is uncommon and when present, the elevation is typically mild.
Prevalence and Characteristics of Post-Stroke CSF Pleocytosis
- CSF pleocytosis (defined as ≥5 WBCs/mm³) occurs in approximately 12.7% of uncomplicated acute ischemic stroke patients when lumbar puncture is performed within 24 hours of symptom onset 1
- When present, the pleocytosis is typically mild, with the highest reported WBC count being around 15 cells/mm³ in uncomplicated stroke 1
- A more recent comprehensive review found pleocytosis prevalence ranging from 0% to 28.6% (mean 11.8%) in ischemic stroke patients without inflammatory or infectious etiology 2
- The highest WBC count reported in stroke patients with common causes of pleocytosis ruled out was 56 cells/mm³ 2
Timing and Resolution
- CSF pleocytosis, when present, is typically observed in the acute phase of stroke 1
- Follow-up lumbar punctures performed at day 7 post-stroke show that pleocytosis typically resolves, with only rare cases of persistent elevation 1
- There is no correlation between CSF pleocytosis and cardiac source of embolus or type of ischemic stroke 1
Differential Diagnosis Considerations
When encountering CSF pleocytosis in a patient with suspected stroke, it's essential to rule out other conditions that commonly cause elevated CSF WBCs 3:
- Viral encephalitis (particularly HSV, VZV, enteroviruses)
- Bacterial meningitis
- Inflammatory conditions
- Subarachnoid hemorrhage
In bacterial meningitis, CSF typically shows much higher WBC counts (often >1000/mm³), low glucose ratio, and higher protein levels compared to the mild pleocytosis seen in stroke 3
In viral encephalitis, CSF typically shows moderate pleocytosis (tens to hundreds of cells), mildly elevated protein, and normal CSF:plasma glucose ratio 3
Interpretation Challenges
- Traumatic lumbar puncture can confound CSF interpretation in stroke patients 1
- For traumatic taps, WBC count can be approximately corrected using the formula: True CSF WBC = actual CSF WBC - (WBC in blood × RBC in CSF)/RBC in blood 3
- However, these correction rules have not been well validated 3
Systemic Inflammatory Response in Stroke
- Stroke itself can trigger a systemic inflammatory response with elevated peripheral WBC counts, particularly in the first 24-48 hours 4
- Mean peripheral WBC count is highest at 0-24 hours post-stroke (8.1 × 10⁹/L) compared to baseline levels at 90 days (6.0 × 10⁹/L) 4
- Elevated peripheral WBC counts in ischemic stroke patients are associated with increased mortality and new vascular events in long-term follow-up 5
Clinical Implications
- Finding mild CSF pleocytosis in a stroke patient should not automatically lead to a change in diagnosis 1, 2
- However, higher levels of pleocytosis (>15-20 cells/mm³) should prompt investigation for alternative or concurrent diagnoses 2
- CSF pleocytosis in stroke has no diagnostic value for stroke subtyping 1
Conclusion
When evaluating CSF findings in stroke patients, clinicians should be aware that mild pleocytosis can occur as a result of the stroke itself. However, significant pleocytosis (>15-20 cells/mm³) is uncommon in uncomplicated stroke and should trigger consideration of alternative diagnoses, particularly infectious or inflammatory conditions.