CHAPTER4 Routine cerebrospinal fluid (CSF) analysis a b a ) F. Deisenhammer, A. Bartos, R. Egg, Albumin CSF/serum ratio (Qalb should be pre- N. E. Gilhus,c G. Giovannoni,d S. Rauer,e ferred to total protein measurement and normal F. Sellebjergf upper limits should be related to patients’ age. Elevated Qalb is a non-specific finding but occurs mainly in bacterial, cryptococcal, and tubercu- Background A great variety of neurological diseases lous meningitis, leptomingeal metastases as well require investigation of the cerebrospinal fluid as acute and chronic demyelinating polyneu- (CSF) to prove the diagnosis or to rule out relevant ropathies. differential diagnoses. Pathological decrease of the CSF/serum glu- cose ratio or an increase in lactate concentration Objectives To evaluate the theoretical background indicates bacterial or fungal meningitis or lep- and provide guidelines for clinical use in rou- tomeningeal metastases. tine CSF analysis including total protein, albumin, Intrathecal immunoglobulin G synthesis is best immunoglobulins, glucose, lactate, cell count, demonstrated by isoelectric focusing followed by cytological staining, and investigation of infec- specific staining. tious CSF. Cellular morphology (cytological staining) should be evaluated whenever pleocytosis is found or Methods Systematic Medline search for the above leptomeningeal metastases or pathological bleed- mentioned variables. Review of appropriate publi- ing is suspected. Computed tomography-negative cations by one or more of the task force members. intrathecal bleeding should be investigated by Grading of evidence and recommendations was bilirubin detection. based on consensus by all task force members. Introduction CSF should be analysed immediately after collec- tion. If storage is needed 12 ml of CSF should The cerebrospinal fluid (CSF) is a dynamic, be partitioned into three to four sterile tubes. metabolically active substance that has many aDepartment of Neurology, Innsbruck Medical Neuroinflammation, Institute of Neurology, University University, Austria; bDepartment of Neurology, Charles College London, Queen Square, London, UK; University, Prague, Czech Republic; cDepartment of eDepartment of Neurology and Clinical Clinical Medicine, University of Bergen, Bergen, Neurophysiology, Albert-Ludwigs University, Freiburg, Norway, and Department of Neurology, Haukeland Germany; f Department of Neurology, Copenhagen University Hospital, Bergen, Norway; dDepartment of University Hospital, Denmark. 14 Huge: “ch04” — 2006/6/29 — 14:54 — page 14 — #1 Section 2: Investigation 15 Table 4.1 Typical constellation of CSF parameters in some neurological diseases. Total protein Glucose ratio Lactate Cell count Typical cytology (g/l) (mmol/l) (per 3.2 µl) Normal valuesa <0.45 >0.4–0.5 <1.0–2.9 <15 MNC Disease Acute bacterial ↑↓↑>1000 PNC meningitis Viral neuro-infections = /↑=/↓=10–1000 PNC/MNC (meningo/encephalitis) Autoimmune ↑=== polyneuropathy Infectious ↑==↑MNC polyneuropathy Subarachnoidal ↑==↑erythrocytes, haemorrhage macrophages, siderophages MNC Multiple sclerosis ====/↑ MNC Leptomeningeal ↑=/↓ NA = /↑ malignant cells, metastases mononuclears CSF, cerebrospinal fluid; MNC, mononuclear cells; PNC, polymorphonuclear cells. ↑/↓, increased/decreased; =, within normal limits; NA, evidence not available. aNormal values are given for lumbar CSF in adults. important functions. It is invaluable as a diag- Search strategy nostic aid in the evaluation of inflammatory con- ditions, infectious or non-infectious, involving A Medline search using the search terms cere- the brain, spinal cord, and meninges as well as brospinal fluid (CSF), immunoglobulin G (IgG) in CT-negative subarachnoidal haemorrhage and immunoglobulin M (IgM), immunoglobulin A in leptomeningeal metastases. CSF is obtained (IgA), and albumin was conducted. Also, the key with relative ease by lumbar puncture (LP). Alter- words ‘cerebrospinal fluid’ or ‘CSF’ were cross- ations in CSF constituents may be similar in dif- referenced with ‘glucose’, ‘lactate’, ‘cytology’, ∗ ∗ ferent pathologic processes and cause difficulties ‘cell in title’ excluding ‘child ’. Furthermore, a in interpretation. Combining a set of CSF vari- search for ‘cerebrospinal fluid’ and ‘immunoglobu- ables referred to as routine parameters (i.e. deter- lin’ and ‘diagnosis’ and ‘electrophoresis’ or ‘isoelec- mination of protein, albumin, immunoglobulin, tric focusing’ was performed limited to the time glucose, lactate, and cellular changes, as well as between 1 January 1980 and 1 January 2005, and specific antigen and antibody testing for infectious returned only items with abstracts, and English agents) will increase the diagnostic sensitivity and language (274 references). A search for ‘cere- specificity. brospinal fluid’ AND ‘infectious’ limited for time The aim of this guideline paper was to pro- (1 January 1980 until now) returned 560 abstracts. duce recommendations on how to use this set of Abstracts that primarily did not deal with diagnos- CSF parameters in different clinical settings and tic issues and infectious CSF (e.g. non-infectious to show how different constellations of these vari- inflammatory diseases, vaccination, general CSF ables correlate with diseases of the nervous system parameters, pathophysiology, cytokines and ther- (table 4.1) (Brainin et al., 2004). apy) were excluded resulting in 60 abstracts. Huge: “ch04” — 2006/6/29 — 14:54 — page 15 — #2 16 Chapter 4: Routine Cerebrospinal Fluid (CSF) Analysis Searching the items ‘cerebrospinal fluid’ AND formulae. The Qalb is a method-independent mea- ‘serology’ limited for time (1 January 1980 until sure, allowing the use of the same reference val- now) and excluding abstracts not directly related ues in different laboratories (Blennow et al., 1993; to the topic returned 35 abstracts and a search for Reiber, 1995). However, there are no conclusive ‘cerebrospinal fluid’ AND ‘bacterial culture’ lim- data on how the Qalb performs compared to total ited for time (1 Jan 1980 until now) resulted in protein as a measure of blood–CSF barrier function 28 abstracts. in large cohorts of unselected patients. The abstracts were selected by the author who There is a concentration gradient for total pro- was in charge of the respective topic. tein and the Qalb along the neuraxis with the In addition, text books and articles identified in lowest concentrations in the ventricular fluid and reference lists of individual papers were selected if the highest concentrations in the lumbar sac considered appropriate. (Thompson, 1988; Fishman, 1992). A significant There are no guidelines for CSF analysis decrease of the Qalb was observed from the first 0– published by the American Academy of Neurol- 4 ml of CSF to the last 21–24 ml of CSF obtained by ogy (AAN). Individual task force members pre- LP (Blennow et al., 1993) (Class I). The Qalb is also pared draft statements for various parts of the influenced by body weight, sex, degenerative lower manuscript. Evidence was classified as Class I–IV back disease, hypothyroidism, alcohol consump- and recommendations as Level A–C according to tion (Class II) and smoking (Class III) (Kornhuber the scheme agreed for EFNS guidelines (Brainin et al., 1987; Skouen et al., 1994; Nyström et al., et al., 2004). When only Class IV evidence was 1997; Seyfert et al., 2002). Posture and physical available but consensus could be reached, the Task activity may influence the CSF protein concentra- Force has offered advice as Good Practice Points tion, resulting in higher CSF protein concentra- (Brainin et al., 2004). The statements were revised tions in inactive, bed-ridden patients (Seyfert et al., and adapted into a single document that was then 2002) (Class III). Elevated CSF protein concentra- revised until consensus was reached. tions can be found in the majority of patients with bacterial (0.4–4.4 g/l), cryptococcal (0.3–3.1 g/l), tuberculous (0.2–1.5 g/l) meningitis and neurobor- Quantitative analysis of total reliosis (Stockstill and Kauffman, 1983; Sabeta, protein and albumin 1985; Kaiser, 1998; Negrini et al., 2000) (Class II). A concentration of >1.5 g/l is specific (99%), but The blood–CSF barrier is a physical barrier, con- insensitive (55%) for bacterial meningitis as com- sisting of different anatomical structures, for the pared to a variety of other inflammatory diseases diffusion and filtration of macromolecules from (Lindquist et al., 1988) (Class I). blood to CSF. The integrity of these barriers and In viral neuroinfections CSF protein concentra- CSF bulk flow determine the protein content of tions are raised to a lesser degree (usually <0.95 g/l) the CSF (Thompson, 1988; Reiber, 1994). In new- (Negrini et al., 2000) (Class II). The concentration borns, CSF protein concentrations are high, but in herpes simplex virus encephalitis is normal in decrease gradually during the first year of life, half of the patients during the first week of illness and are maintained at low levels in childhood. (Koskiniemi et al., 1984) (Class IV). In adults, CSF protein concentrations increase Non-infectious causes for an increased CSF pro- with age (Eeg-Olofson et al., 1981; Statz and tein and sometimes with an increased cell count Felgenhauer, 1983) (Class I). The CSF to serum include subarachnoidal haemorrhage, central ner- albumin concentration quotient (Qalb) can also vous system (CNS) vasculitis, and CNS neoplasm be used to evaluate blood–CSF barrier integrity (Jerrard et al., 2001) (Class IV). Elevated total pro- (Andersson et al., 1994). The Qalb is not influenced tein concentration