Lower Values for Immunoglobulin M in Cerebrospinal Fluid When Sampled with an Atraumatic Sprotte Needle Compared with Conventional Lumbar Puncture

Abstract

SUMMARY. Immunoglobulin M (lgM) has a very low concentration in cerebrospinal fluid (CSF) compared with serum, and therefore determinations of IgM in CSF are highly sensitive to pre-analytical errors caused by contamination with serum or interstitial fluid. Capillary attraction causes a thin layer of liquid containing serum proteins to be formed inside a conventional (Quincke) needle during penetration of tissue. To investigate this source of pre-analytical error, 35 patients had lumbar punctures using a 22 G atraumatic (Sprotte) or 25 G conventional (Quincke) needle according to a randomized scheme, and the IgM concentrations in CSF and serum were determined.The CSF IgM concentrations for samples taken with a Sprotte needle were significantly lower than those taken with a Quincke needle (P< O·05), whereas the corresponding serum IgM concentrations and CSF erythrocyte counts did not differ significantly. The difference indicates that CSF IgM concentrations determined after conventional sampling may be falsely increased by contamination. We conclude that IgM concentrations in CSF samples taken with the atraumatic technique are more accurate, and recommend the use of this technique when CSF IgM is to be determined. Additional key phrases: CNS infections; multiple sclerosis; pre-analytical errorsPre-analytical errors are often overlooked. In a recent study' we proposed that falsely increased levelsof immunoglobulin M (lgM) in cerebrospinal fluid (CSF) might be caused by contamination with small amounts of serum. Such contamination falsely increases the concentrations of all components which are present in serum at higher concentration than in CSF, and the relative error increases with decreasing CSF-serum ratio. Hence, trace contamination can significantly alter the CSF concentration of large molecular mass molecules, such as IgM, whereas the albumin and IgM concentrations are only negligiblyinfluenced.A pilot study revealed that coloured solutions could form a thin layer at the inside of a conventional (Quincke) spinal needle by capillary Correspondence: Dr S Ohman. 210attraction. This degree of contamination was sufficient to account for more than a 1001170 increase in the CSF IgM concentration.The pilot study led to the present study, where a conventional sampling technique/ was compared with sampling using Sprotte needles. These needles have an atraumatic, non-cutting edge minimizing damage to peripheral tissue before entering the lumbar sac. ' The aim of this study was to investigate whether sampling using atraumatic Sprotte needles could diminish the potential pre-analytical error caused by a liquid layer on the inside of the cannula. MATERIAL AND METHODSDiagnostic lumbar puncture (LP) was performed because of suspected infections of the central

Consensus guidelines for lumbar puncture in patients with neurological diseases

“…However, atraumatic needles are recommended by most of the 37 articles as the best needle to perform LPs. Indeed, when comparing different needle designs, atraumatic needles resulted in a lower prevalence of post‐LP complaints, including PLPH, low back pain or nausea/vomiting (Table 4) [5,36,48,49,53,54,57,58,60,61,63–67,71,75,79–91]. A lower frequency of complications results in reduced health care costs due to less medication or medical assistance, such as blood patches [48,49,53,54,57,61,64,66,75,79–84,86–91,93,96].…”

The impact of preanalytical variables on measuring cerebrospinal fluid biomarkers for Alzheimer's disease diagnosis: A review

“…However, current protocols all recommend an atraumatic (penpoint) needle, although with different sized gauges (22, 24 or 25 G; Table 1). A study found that conventional needles (compared with atraumatic ones) led to minor serum protein contamination of CSF [104], though this may not affect AD CSF biomarker concentrations (see section 4.2.6).…”