Pain processes in tennis elbow illuminated by PET scanning

Physiological processes in soft tissue pain such as chronic tennis elbow can be explored using diagnostic imaging methods. This is demonstrated by researchers from Uppsala University. The pain physician and researcher Magnus Peterson is presenting a new use of positron emission tomography (PET) and a tracer for the signal receptor NK1 for visualizing a physiological process. Chronic pain is a major problem, with considerable socio-economic costs and suffering of the individual. Musculoskeletal pain is the most common type of pain and is one of the most common reasons for consultation in health care. However, pain from soft tissues, (i.e. pain from muscles, tendons and ligaments) is still lacking effective methods for localization and diagnosis of underlying pathophysiological mechanisms. This means that diagnosis still depends on clinical examination, which provides no guidance regarding what mechanisms might underlie the pain. Consequently, treatment proceeds purely on an empirical basis. Magnus Peterson has worked with PET, a tool for diagnostic imaging, in combination with a specific tracer for the signal receptor NK1.
The tracer is injected into the blood where it circulates through the body and binds to available NK1 receptors. The signal from the radioactive tracer can then be captured as an image outside the body using PET.
This is the first time an up-regulation of NK1 receptors has been visualized by diagnostic imaging in painful tissue in humans. The study clearly reveals an image of elevated levels of NK1 in the painful area compared with the healthy arm.
Following tissue damage there is an up-regulation of the neuropeptide substance P and its receptor NK1. This occurs not only in the dorsal horn of the spinal cord, but also in the peripheral painful tissue. This up-regulation is part of an interaction between peripheral nerves, immune cells, and the tissue itself that seems to help guide the body