Changes in neurotrophic and inflammatory factors in the cerebrospinal fluid of patients with postherpetic neuralgia

Abstract

Inflammatory and neurotrophic factors are involved in postherpetic neuralgia (PHN), but the association of these factors in the cerebrospinal fluid (CSF) with the level of pain is poorly known. The present study aimed to examine the changes in neurotrophic and inflammatory factors in the CSF of patients with PHN and to study the correlation between these factors and the degree of pain. Fifty patients with PHN and 28 patients with hemifacial spasm (as controls) were recruited between May 2015 and March 2016. CSF levels of inflammatory and neurotrophic factors were measured by ELISA. Compared with controls, patients with PHN had lower CSF levels of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin (NT)-3, NT-5, and P substance (all P<0.05), and higher CSF levels of interleukin (IL)-1β (P=0.050). Among patients with PHN, CSF BDNF levels were positively correlated to IL-8 (rs=0.229, P=0.04); glial cell line-derived neurotrophic factor (GDNF) levels to IL-8 (rs=0.326, P=0.004) levels; NGF levels to tumor necrosis factor (TNF)-α levels (rs=0.229, P=0.044); NT-3 levels to IL-1β (rs=0.228, P=0.045); and NT-5 levels to IL-8 (rs=0.388, P<0.001), and TNF-α (rs=0.445, P<0.001) levels. Inflammatory and neurotrophic factors were not correlated with the visual analog scale score and von Frey. Multivariable linear regression showed PHN was associated with NGF (P=0.038) and BDNF (P=0.029), independently from age and major medical history. In conclusion, patients with PHN showed low levels of BDNF, NGF, NT-3, and NT-5. Among patients with PHN, CSF levels of neurotrophic factors positively correlated with inflammatory factors.