【medical-news】Chronic Pain Harms The Brain
ScienceDaily (Feb. 6, 2008) — People with unrelenting pain don't only suffer from the non-stop sensation of throbbing pain. They also have trouble sleeping, are often depressed, anxious and even have difficulty making simple decisions.
In a new study, investigators at Northwestern University's Feinberg School of Medicine have identified a clue that may explain how suffering long-term pain could trigger these other pain-related symptoms.
Researchers found that in a healthy brain all the regions exist in a state of equilibrium. When one region is active, the others quiet down. But in people with chronic pain, a front region of the cortex mostly associated with emotion "never shuts up," said Dante Chialvo, lead author and associate research professor of physiology at the Feinberg School. "The areas that are affected fail to deactivate when they should."
They are stuck on full throttle, wearing out neurons and altering their connections to each other.
This is the first demonstration of brain disturbances in chronic pain patients not directly related to the sensation of pain.
Chialvo and colleagues used functional magnetic resonance imaging (fMRI) to scan the brains of people with chronic low back pain and a group of pain-free volunteers while both groups were tracking a moving bar on a computer screen. The study showed the pain sufferers performed the task well but "at the expense of using their brain differently than the pain-free group," Chialvo said.
When certain parts of the cortex were activated in the pain-free group, some others were deactivated, maintaining a cooperative equilibrium between the regions. This equilibrium also is known as the resting state network of the brain. In the chronic pain group, however, one of the nodes of this network did not quiet down as it did in the pain-free subjects.
This constant firing of neurons in these regions of the brain could cause permanent damage, Chialvo said. "We know when neurons fire too much they may change their connections with other neurons and or even die because they can't sustain high activity for so long," he explained.
'If you are a chronic pain patient, you have pain 24 hours a day, seven days a week, every minute of your life," Chialvo said. "That permanent perception of pain in your brain makes these areas in your brain continuously active. This continuous dysfunction in the equilibrium of the brain can change the wiring forever and could hurt the brain."
Chialvo hypothesized the subsequent changes in wiring "may make it harder for you to make a decision or be in a good mood to get up in the morning. It could be that pain produces depression and the other reported abnormalities because it disturbs the balance of the brain as a whole."
He said his findings show it is essential to study new approaches to treat patients not just to control their pain but also to evaluate and prevent the dysfunction that may be generated in the brain by the chronic pain.
The study will be published Feb. 6 in The Journal of Neuroscience. Chialvo's collaborators in this project are Marwan Baliki, a graduate student; Paul Geha, a post-doctoral fellow, and Vania Apkarian, professor of physiology and of anesthesiology, all at the Feinberg School.
screen.width-333)this.width=screen.width-333" width=300 height=300 title="Click to view full brain.jpg (300 X 300)" border=0 align=absmiddle> 原文
Beyond Feeling: Chronic Pain Hurts the Brain, Disrupting the Default-Mode Network Dynamics ( The Journal of Neuroscience, February 6, 2008, 28:1398-1403; )
[abstract ] Chronic pain patients suffer from more than just pain; depression and anxiety, sleep disturbances, and decision-making abnormalities (Apkarian et al., 2004a) also significantly diminish their quality of life. Recent studies have demonstrated that chronic pain harms cortical areas unrelated to pain (Apkarian et al., 2004b; Acerra and Moseley, 2005), but whether these structural impairments and behavioral deficits are connected by a single mechanism is as of yet unknown. Here we propose that long-term pain alters the functional connectivity of cortical regions known to be active at rest, i.e., the components of the "default mode network" (DMN). This DMN (Raichle et al., 2001; Greicius et al., 2003; Vincent et al., 2007) is marked by balanced positive and negative correlations between activity in component brain regions. In several disorders, however this balance is disrupted (Fox and Raichle, 2007). Using well validated functional magnetic resonance imaging (fMRI) paradigms to study the DMN (Fox et al., 2005), we investigated whether the impairments of chronic pain patients could be rooted in disturbed DMN dynamics. Studying with fMRI a group of chronic back pain (CBP) patients and healthy controls while executing a simple visual attention task, we discovered that CBP patients, despite performing the task equally well as controls, displayed reduced deactivation in several key DMN regions. These findings demonstrate that chronic pain has a widespread impact on overall brain function, and suggest that disruptions of the DMN may underlie the cognitive and behavioral impairments accompanying chronic pain.
作者:admin@医学,生命科学 2011-06-07 05:14