Special issue on microglia and chronic pain.

This special issue of Experimental Neurology is devoted to the role of Microglia and Chronic Pain. Chronic pain affects 116 million people per year in the United States, which is more than heart disease, cancer, and diabetes combined. Nervous system trauma and disease are principal contributors to the establishment of chronic pain in people and in animal models. Central nervous system (CNS) injury or tumor development, peripheral nerve injury, multiple sclerosis, diabetes and many other neurological disruptions can serve as the instigating pathophysiolgical conditions that lead to chronic pain. Once considered to function solely as the phagocytotic cells of the CNS, more recent work has demonstrated that persistent activation of the microglial population may contribute to continued dysfunction including chronic pain. In the invited articles for this special issue on Microglia and Chronic Pain, we present evidence for the role of persistent microglial activation in chronic pain after peripheral and central nervous system injury, as well as in diabetic pain, post-herpetic neuralgia pain and related diseases. Collectively, the body of work indicates the importance of understanding the roles of microglial cells in chronic pain which will lead to targeted treatment to attenuate or alleviate chronic neuropathic pain syndromes.