What is the significance of a cerebrospinal fluid (CSF) cell count with a white blood cell (WBC) count of 19 cells per microliter, consisting of 42% segmented neutrophils (Segmenters) and 58% lymphocytes?

From the Guidelines

The cerebrospinal fluid analysis indicates a mild inflammatory process in the central nervous system, suggesting either a viral infection, a partially treated bacterial infection, or another inflammatory condition. The CSF white blood cell (WBC) count of 19 cells per microliter with 42% segmenters (neutrophils) and 58% lymphocytes is abnormal, as normal CSF typically contains fewer than 5 WBCs per microliter, almost exclusively lymphocytes 1. Key considerations for the differential diagnosis include:

• Viral infections, which can cause a lymphocytic predominance in the CSF
• Partially treated bacterial infections, which may present with a mixed cell population
• Other inflammatory conditions affecting the brain or spinal cord, such as meningitis or encephalitis, which can have varying CSF profiles Further evaluation with additional CSF studies, such as protein, glucose, culture, and PCR testing for specific pathogens, as well as clinical correlation with the patient's symptoms and imaging studies, is necessary to establish a definitive diagnosis 1. It is also important to consider the patient's age, immune status, and other risk factors, as certain pathogens are more common in specific populations, such as Listeria monocytogenes in older adults and the immunocompromised 1. Given the potential for serious conditions, such as meningitis or sepsis, which can have high morbidity and mortality rates, particularly in older adults or those with compromised immune systems 1, prompt and thorough evaluation is crucial.

From the Research

Cerebrospinal Fluid Cell Count Differential Count

• The given cerebrospinal fluid (CSF) analysis shows a white blood cell (WBC) count of 19 cells per microliter, with 42% segmenters and 58% lymphocytes.
• According to a study published in 2001 2, a CSF WBC count of 30 cells per microliter or less has a negative predictive value of 99.3% for bacterial meningitis.
• However, the same study notes that other factors, such as age, CSF glucose, protein, gram stain, CSF-serum glucose ratio, and peripheral blood band count, should also be considered when managing patients with suspected bacterial meningitis.
• A more recent study from 2022 3 evaluated the use of the BioFire® FilmArray® Meningitis/Encephalitis Panel in immunocompromised and nonimmunocompromised patients, and found that redundant testing was common, and guideline adherence could have safely decreased panel use by 41%.

Interpretation of Results

• The presence of 19 WBCs per microliter in the CSF, with a differential count of 42% segmenters and 58% lymphocytes, may indicate a possible infection or inflammation in the central nervous system.
• However, as noted in the study from 2021 4, CSF analysis is not necessarily diagnostic, and other tests, such as CSF culture, lactate measurement, and polymerase chain reaction testing, may be needed to confirm the diagnosis.
• The study from 2001 2 suggests that children older than 6 months with 30 CSF WBCs per microliter or less are at low risk for bacterial meningitis, but this may not apply to adults or immunocompromised patients.

Clinical Significance

• The results of the CSF analysis should be interpreted in the context of the patient's clinical presentation, medical history, and other laboratory tests.
• As noted in the study from 2022 3, clinically significant results can occur in immunocompromised patients with low CSF WBC counts, and clinical decision support may be needed to reduce unnecessary testing and result in significant cost savings.
• The study from 2019 5 recommends the use of empiric vancomycin plus a third-generation cephalosporin for suspected bacterial meningitis, but this should be guided by the patient's specific clinical situation and laboratory results.