020-22 – The utility of leukocyte differential in infectious and inflammatory conditions of the Central Nervous System (CNS)?

Background/aims:

Central Nervous system (CNS) inflammation and infections are associated with a high morbidity and mortality. Therefore, timely management is required to improve prognosis. The most accessible and widely used test to establish diagnosis is a lumbar puncture and hence cerebrospinal fluid (CSF) analysis. The difficulty arises when the CSF cell count is low.

This study therefore aims to determine whether the leukocyte differential, when between 5-50 cells/mm3, is useful in diagnosing and hence managing patients presenting with signs and symptoms of CNS inflammation/infections.

Methods:

Retrospective study conducted at the Walton Centre Liverpool, collecting patient data for the last 50 samples with a CSF cell count 5-50cells/mm3 presenting prior to September 2019. Data determined from clinical notes, both paper notes and online systems such as EP2.

Results/discussion:

50 samples for 48 patients included, with majority being MS (n=17), “other inflammatory conditions” (n=8), and meningitis (n=2). Others were not inflammatory/infectious CNS conditions. A lymphocyte predominant picture was seen in all patients with MS and seven patients in the “other inflammatory conditions” category. The viral meningitis also showed a lymphocytic predominance, whereas the bacterial case of meningitis had a polymorph predominance, which is to be expected.

Conclusions:

Although, the patterns seen in each category shows that the CSF differential played a role in guiding management, only the two meningitis cases were solely confirmed by the CSF differential count. Others were further confirmed by various other tests such as MRI/CT scans, electrophysiological studies and the presence of oligoclonal bands.

However, a similar, larger scale study is needed to confirm these findings, which includes only cases with an inflammatory/infectious aetiology.