Monday, March 26, 2007

Sound Medicine: Pain and the Brain (click on Real Media or Windows Media for audio)

Pain and the brain

Air date: March 15, 2003

The brain controls the pathways and chemicals that produce pain, and thanks to medical research today we understand much about pain relief. But brain researchers are still exploring new ways for relieving pain, especially chronic pain. We hear more from Michael Vasko, MD, professor of pharmacology at the Indiana University School of Medicine.

Nerves in our skin and organs communicate signals from the body to the brain. Some nerves (also called sensory neurons) carry touch signals, but others carry sensations, some of them noxious, like pain. When activated, the nerves conduct the signal to the spinal cord, to the brain, and to the center of the brain, which perceives it as bad. The brain then causes us to register a response -- to cry out or pull away.

Dr. Vasko discusses nerve stimuli, body chemicals called prostaglandins, and the basic mechanism that causes many pain medications, including new ones like COX-2 inhibitors (i.e. Celebrex) to work. Although it's unclear why people perceive pain and respond to drugs differently, Dr. Vasko explains how new techniques in brain imaging can help researchers understand how pain signals travel through the somatosensory cortex.

Of especial interest to Dr. Vasko is chronic pain, which modern drugs do not treat well. We often don't even know what causes chronic pain, he says, since often the injury itself is gone. It's a "neuropathic pain," a pathology of the nerves. One syndrome is "central pain," a lesion in the brain; another is "phantom limb" pain. Imaging techniques might help solve the riddle, perhaps by revealing ways we can train the brain to adapt. Dr. Vasko talks about current, holistic treatments for chronic pain. He also explains how gene therapy may help reduce people's sensitivity to pain.

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