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Table of Contents
atrophy - wasting away
axon - thin connection which carries signals between neurons
chronic - long lasting
control - in an experiment, a group - usually healthy - used as a basis
for comparison gray matter -
part of the brain composed primarily of neuron bodies, as opposed to
white matter morphology -
the study of the structure and form of something as opposed to it's function
neocortex - large portion of the brain thought to be responsible for
higher order functions
neocortical - relating to the neocortex
neuron - a nerve cell
neuropathic pain - pain which is due to damage to the nervous system
prefrontal cortex - region at the front of the brain thought to be
responsible for planning and other high-level thought processes
sciatic nerve - nerve which originates in the lower back and serves
the legs thalamus - part of
the brain, located near the brain stem, which acts as a relay to send
sensory information (like pain) to other parts of the brain
white matter - part of the brain which contains primarily axons |
Chronic pain prematurely ages the brain. That
was the most significant - and disturbing - finding of a group of
researchers from Northwestern University. Scientists have known for
some time that chronic pain alters neurons in the spine, but Dr. Apkarian, a
neuroscience researcher, and his colleagues wanted to know if and how chronic pain
effected the structure of the brain.
In order to study this, Dr. Apkarian and his team used
MRI's to measure the volume and density of the brains of 26 people with
chronic back pain (CBP) and compared them to the brains of 26 healthy
volunteers. They published their results in the November 17, 2004
issue of the Journal of Neuroscience.
Each of the 26 members of the pain group had
experienced unrelenting pain for more than a year in their lower back.
In some, the pain radiated down into the legs, in others it didn't. In
addition to the brain MRI's the CBP subjects reported their pain intensity
and how long they had been in pain. To aid in the analysis, members of
the pain group were also classified as having neuropathic pain - due to
nerve damage - or non-neuropathic pain. The 26 volunteers that
composed the control group were recruited to match the age and gender makeup
of the CBP group as closely as possible.
The researchers used two different techniques to
measure the volume of the neocortical gray matter (the part of the brain
responsible for most higher order functions) from the MRI's. They
found that overall, the subjects in the pain group had 5%-11% less gray
matter volume than the control subjects, a statistically significant finding.
People normally lose about 0.5% of their gray matter each year as they age,
so this result translates to the pain patients experiencing 10-20 years of
aging compared to the control group.
In looking at neuropathic versus non-neuropathic pain,
the team found that in the neuropathic pain group, the volume loss was
related to pain duration. In fact, in the neuropathic group, each year
of pain equated to a 0.2% loss in gray matter (1.3cm3). In
the non-neuropathic group, pain duration was not related to volume loss.
The neuropathic pain group also fared worse when the
team measured the density of the gray matter in specific regions of the
brain. In the prefrontal cortex - responsible for high level
functions - they found that people in neuropathic pain had gray matter that
was 27% less dense than the control group, and people with non-neuropathic
pain had gray matter that was 14% less dense. They also found that the
thalamus - a region of the brain which relays pain and other sensations -
was significantly less dense in the pain group as compared to the control
group.
Although this study can not prove it conclusively, the
authors believe the results mean that the chronic back pain is causing brain
tissue to atrophy in certain areas. If proven to be true, this would
mean that chronic pain not only alters the neurons of the spine, but has a
structural effect all the way to the brain as well. While it is a significant
finding, it is also important to keep in mind that this study looked at
chronic back pain specifically and the results may be different for other
types of chronic pain.
Still, with millions of people in the US alone
suffering from chronic pain, and with neuropathic pain an all too common
problem for CM/SM patients, this area of research is definitely worth
paying attention to..
--Rick Labuda
Back to Table of Contents |
Key Points
-
It is known that chronic pain alters
the neurons in the spine
-
Researchers wanted to find out if
chronic pain also affected the brain
-
Used MRI's to compare the volume and
density of gray matter in the brain's of 26 people with chronic back pain to
26 healthy controls
-
Using two different techniques,
found that on average, the volume of gray matter was 5%-11% smaller in the
pain patients than the volunteers
-
This volume reduction corresponds to
10-20 years of normal aging
-
Also found a decrease in the density
of gray matter - in specific regions of the brain - among the pain group
-
Among those with neuropathic pain,
the results were related to pain duration
-
Although not proven in the study,
researchers believe these results indicate that chronic pain - especially
neuropathic pain - causes atrophy in parts of the brain
Related C&S News Articles:
Talking About Chronic
Pain
The High Cost Of Neuropathic
Pain
How Neck & Arm Pain Affect Overall Health
How Much Do Opioids
Help With Chronic Pain?
Looking at how people combat chronic pain Book Review:
The
Truth About Chronic Pain: Patients and Professionals on How to Face
It, Understand It, Overcome It...by Arthur Rosenfeld |