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Overview of the Decade of Pain

January 5th, 2009 (07:20 pm)

  An Expert Interview With Joshua P. Prager, MD, MS

Joshua P. Prager, MD, MS
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Editor's Note:

The American Academy of Pain Medicine (AAPM) 24th Annual Meeting took place
from February 12 to 16, 2008, in Orlando, Florida. During this meeting,
new information about the diagnosis, treatment, and management of acute
pain, chronic pain, and breakthrough pain (BTP) was presented. Darlene
Field, PhD, Medscape Neurology & Neurosurgery Scientific Director,
discussed the highlights of the "Decade of Pain" keynote address with
Joshua P. Prager, MD, MS, Director, Center for the Rehabilitation of
Pain Syndromes (CRPS), and Immediate Past President, North American
Neuromodulation Society (NANS) . Dr. Prager delivered the "Decade of
Pain" lecture at the 2007 annual meeting of the AAPM.

Can you discuss some important findings presented at the AAPM meeting
you just attended -- specifically, was any new knowledge shared at the
Decade of Pain lecture given by Dr. Michael Cousins?

Joshua P. Prager, MD, MS:
he keynote lecture at the meeting was given by Dr. Michael Cousins,
who is Professor and department head of Anesthesia and Pain Management,
University of Sydney, Sydney, Australia. Dr. Cousins made 3 main points
in his lecture. The first point was that pain is a disease in its own
right. The concept of persistent pain as a disease entity leads us
toward new specific treatments aimed at physical, psychological, and
environmental components of the disease, and takes into account the
possibility of a genetic predisposition to experience pain. Dr. Cousins
explained that persistent pain has a prevalence of 1 in 5 in the
general population, and the studies conducted by the Pain Management
Research Institute of Sydney, Australia, indicate that pain leads to an
annual cost of $1.85 billion per million of the population.

The second point made was that the medical community has now recognized
that additional specialty training in pain management is absolutely
necessary. There are too few true pain medicine specialists being
trained, and many patients have limited or no access to effective pain

Dr. Cousins' final main point was that pain management
needs to truly become a fundamental human right. To achieve this goal,
we need parallel initiatives in medicine, law, ethics, and politics.

Medscape: Did Dr. Cousins offer any evidence to lend credence to the fact that pain itself is a disease?

Dr. Prager:
Well we always knew that persistent pain is very different from acute
pain and we can now demonstrate those differences with imaging studies
of the brain. A functional magnetic resonance image (MRI) of a patient
with chronic pain will appear quite different from that of a MRI of a
patient with acute pain. For example, an imaging study just published
last week in the Journal of Neuroscience demonstrated that
chronic pain harms cortical areas, indicating that chronic pain has a
widespread impact on overall brain function (Figure).[1]
Several areas of the brain in patients in chronic pain fail to
deactivate during the attention task compared with healthy patients.

The pictures below are brain fMRI data (right images of the brain are
seen from the head's midline, left images are from the side) showing
the average brain activity during the entire task. Colors illustrate
how much activation (red-yellow) or deactivation (dark/light blue) was
found at each brain location during the attention task. The main result
here is that brain images of patients in chronic pain exhibit a
significantly smaller territory of brain deactivating (ie, in blue)
during the task than healthy individuals. For more information, see
www.chialvo.net. Reprinted with permission from Dante R. Chialvo, MD.

Click to zoom
Figure 1. 

If pain persists despite reasonable efforts to manage it by the patient's
general practitioner and specialists, then consultation with a
board-certified pain medicine specialist is absolutely necessary.
Because pain is a disease, it is important to manage the pain early on
to prevent the pain from becoming a persistent problem, with all of the
attached disease changes that occur.

Medscape: After listening to the Decade of Pain lecture, what do you think is in store for the future of pain management?

Dr. Prager:
As we look toward the future of pain management, the treatment of
persistent pain will be markedly different from how we currently treat
it. Instead of using drugs like morphine that only provide symptom
relief, newer drugs will aim at the disease process. Dr. Cousins
mentioned a new class of drugs in development, subtype selective sodium
channel blockers. Pain-sensing neurons of the peripheral nervous system
express several sodium channel subtypes, and pharmacologic agents that
target the Na 1.8 selective small molecule sodium channel are currently
in development.

Medscape: Was there any discussion of the role of genetics in pain medicine?

Dr. Prager:
Yes, Dr. Cousins presented some really fascinating data that suggest
that genetic analysis of patients may indicate who would be predisposed
to persistent pain, for example after a mastectomy, vs who wouldn't. If
the genetic analysis demonstrates a patient to be at risk for chronic
pain, then more aggressive maneuvers would be necessary related to that
surgery; whereas, somebody whose genetics would not predispose him or
her to persistent pain wouldn't need the same intensity of treatment

Genetic analysis to determine who is prone to
chronic pain vs who is not is a very new concept. It is also very
costly. To do a complete genetic analysis of a patient at this time
costs about a million dollars, which is much less than it used to be.
As a matter of fact, James Watson recently had a genetic analysis
completed on himself, being one of the first ever to take advantage of
the Human Genome Project. Right now we are still a long way from
determining which genes would make someone more susceptible to
experiencing pain than others.

Medscape: Is there anything
else you would like to mention? Particularly, any important take home
messages from Dr. Cousin's lecture?

Dr. Prager: Yes, there were some very compelling data presented from a study done at Kaiser Permanente Northwest that I would like to mention.[2]
In an analysis of 1997 and 1998 data in Salem, Oregon, Kaiser
Permanente Northwest was able to demonstrate that by having a pain
service (a multidisciplinary pain management group) to serve their
community, they were able to reduce emergency room visits by 43%.
Patients with chronic pain who think their pain is discounted by
physicians often overuse medical services like emergency departments to
identify the cause of their pain or to prove to physicians that their
pain is real.

Supported by an educational grant from PriCara,
Division of Ortho-McNeil-JanssenPharmaceuticals Inc., administered by
Ortho-McNeil Janssen Scientific Affairs, LLC.

From the desk of the matrix777
This is part 2 in my series on pain.