Pleocytosis in Cerebrospinal Fluid Following Multiple Lumbar Punctures in Healthy Volunteers

Pleocytosis (white blood cell [WBC] N 5/μL) [1] is commonly reported in studies involving lumbar puncture (LP), but the contributing role of LP in pleocytosis has been obfuscated by the inclusion of patient populations, which may add confounding factors such as disease state or underlying injury. As LP is often performed as a diagnostic tool, many studies have observed pleocytosis following LP in the context of various diseases and injuries to the central nervous system (CNS) [2–6]. Several medical textbooks suggest pleocytosis may be a normal side effect following repeated lumbar puncture, but do not cite controlled studies in healthy subjects to substantiate this statement [7,8]. Only a handful of studies have examined the incidence of pleocytosis following repeated lumbar puncture in healthy subjects, and most focus on pediatric populations. [9,10]. The lack of current data on the incidence of pleocytosis in healthy adult subjects undergoing repeated lumbar puncture is relevant due to the recent interest in utilizing CNS biomarkers in psychiatric research. We sought to address this deficiency via the following retrospective review.