Cytokine expression in serum and cerebrospinal fluid in non-inflammatory polyneuropathies

• Published in: Journal of neurology, neurosurgery and psychiatry Vol. 79; no. 11; pp. 1268 - 1274
• Main Authors: Ludwig, J, Binder, A, Steinmann, J, Wasner, G, Baron, R
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd 01.11.2008; BMJ; BMJ Publishing Group LTD
• Subjects: Biological and medical sciences; Cerebrospinal fluid; Cytokines; Demography; Diabetes; Diabetes Mellitus - epidemiology; Diabetic neuropathy; Disability Evaluation; Enzymes; Female; Health Status; Humans; Interleukin-6 - blood; Interleukin-6 - cerebrospinal fluid; Investigations; Male; Medical sciences; Middle Aged; Multiple sclerosis and variants. Guillain barré syndrome and other inflammatory polyneuropathies. Leukoencephalitis; Nervous system; Neurology; Pain; Paresthesia - diagnosis; Paresthesia - epidemiology; Polyneuropathies - blood; Polyneuropathies - cerebrospinal fluid; Polyneuropathies - epidemiology; Severity of Illness Index; Thiamine Deficiency - epidemiology; Tumor Necrosis Factor-alpha - blood; Tumor Necrosis Factor-alpha - cerebrospinal fluid; Tumor necrosis factor-TNF; Vitamin B 12 Deficiency - epidemiology; Vitamin B 6 Deficiency - epidemiology; Nervous system diseases; Peripheral nerve disease; Cerebrospinal fluid; Polyneuropathy; Cytokine
• ISSN: 0022-3050; 1468-330X; 1468-330X
• DOI: 10.1136/jnnp.2007.134528

Background:Pain is a common symptom in polyneuropathies (PNPs), although it is still not known why some PNPs are painful and others are painless. Increased pro-inflammatory cytokines have been found in conditions resulting in exaggerated pain states in animal studies. Recently, elevated pro-inflammatory cytokine levels have also been found in the cerebrospinal fluid (CSF) of patients suffering from complex regional pain syndrome. Pro-inflammatory cytokines have been shown to induce or increase inflammatory or neuropathic pain.Methods:Using chemiluminescent enzyme immunometric assays, cytokine levels in 36 patients with painful and painless non-inflammatory PNPs in serum and CSF were investigated. The severity of PNPs was measured with electroneurography (ENG). In subjects with normal results using conventional ENG, quantitative thermo-testing was performed to investigate small-nerve-fibre function.Results:Interleukin (IL)-6 and tumour necrosis factor (TNF)-α in serum or CSF did not differ between patients with (n = 18) or without (n = 18) painful PNPs, whereas patients with mechanical allodynia (n = 5) had elevated serum TNF-α levels compared to those without allodynia. TNF-α and IL-6 serum levels were higher in patients with severe (n = 21) compared to those with mild neuropathy (n = 15), and showed a positive correlation with severity of neuropathy.Conclusions:Results suggest that nerve fibre degeneration and presence of mechanical allodynia in peripheral non-inflammatory neuropathy determine cytokine expression in serum.