WHAT'S
NEW -- July 1999
Neurologists
Lack Pain Management Training
A
recent study performed by one of our departmental faculty
evaluated the pain management education that practicing neurologists
obtain in the residency training. Three hundred and thirteen
randomly selected neurologists across the United States responded
to this survey study. Only 30% of these neurologists reported
being adequately trained to diagnose pain disorders and only
20% felt adequately trained to treat pain disorders. Approximately
90% of respondents stated that more pain management education
needs to be given to neurology residents (doctors in training)
and to neurologists currently in practice.
Galer BS, Keran C, Frisinger M. Pain medicine education among
American neurologists: A need for improvement. Neurology
1999, 52:1710-1712.
Editor's
Note: Even though neurologists are often expected to be the
"pain specialist" in a community, the unfortunate
fact is that most neurologists do not obtain any specific
pain management training. Importantly, neurologists are acknowledging
a need for more education regarding pain management.
 
Is Postherpetic Neuralgia More Than One Condition?
A most provocative and interesting article was published recently
by premier pain researchers from University of California
San Francisco, Drs. Michael Rowbotham, Karin Petersen, and
Howard Fields. Based on their extensive research experience
with postherpetic neuralgia (PHN -- chronic shingles pain),
these scientists hypothesize that the pain of PHN may have
a variety of different mechanisms and that "the clinical
picture of PHN falls into distinct patterns based on differing
pathophysiology." They present three different subtypes
of PHN, which they feel may respond to different treatments:
| 1. |
Irritable
Nociceptor subtype = significant allodynia (skin
sensitivity)/prolonged relief with local anesthetic injected
into the painful skin/increased pain with epinephrine
injected into the painful skin/severe burning with capsaicin
on the skin; |
| |
|
| 2. |
Deafferented
Nonallodynic subtype = no allodynia/no change
with local anesthetic injected into the painful skin/no
change with epinephrine injected into the painful skin/no
sensation with capsaicin on the skin; |
| |
|
| 3. |
Deafferented
Allodynic subtype = variable allodynia/short term
allodynia relief with local anesthetic injected into the
painful skin/no significant change with epinephrine injected
into the painful skin/variable relief with capsaicin on
the skin. |
Rowbotham MC, Petersen KL, Fields HL. Is Postherpetic Neuralgia
More Than One Disorder? Pain Forum 1998; 7:231-237
Editor's
Note: For several years clinical researchers, including this
team, have been stating that neuropathic pain disorders, such
as PHN, are most likely composed of heterogeneous groups of
patients with different pathophysiological mechanisms. This
paper is the first attempt to utilize clinical and scientific
data and propose such a subgrouping. This hypothesis needs
to be further tested in clinical studies before these subtypes
are accepted as scientifically valid.
Multidisciplinary
Headache Treatment Is Effective
This study assessed the effectiveness of comprehensive headache
treatment, which could include aggressive drug therapy, psychological
therapy, biofeedback, physical therapy, and anesthesiology
techniques; therapy was individually tailored based on initial
physician assessment. A questionnaire was mailed to patients
6 months after treatment. These investigators reported significant
improvements in frequency of headaches, number of days with
work impairment or absence due to headache, less physician
visits for headache care, and treatment satisfaction (89%
satisfied). As Saper and colleagues concluded, "Öthe
results support the concept that matching intensity of treatment
(comprehensive/tertiary care) to severity of illness (complex/refractory
cases) is cost-effective."
Saper JR, Lake AE, Madden SF, Kreeger C. Comprehensive/Tertiary
Care For Headache: A 6-Month Outcome Study. Headache
1999; 39:249-263
Editor's
Note: Chronic headache, including migraine, cluster, traumatic,
and tension-type headaches, can be very debilitating and require
more than just medication treatment. Indeed, many headache
patients are currently treated in a "multidisciplinary"
method, that is, obtaining many different types of therapies
to improve their headache condition, such as medication, psychological
therapies, biofeedback, physical therapy, and nerve blocks.
This study shows the significant benefits of such a comprehensive
treatment approach for the patient and also for society and
the health care industry, since patients are able to work
more productively and require less doctor visits.
Genetics of Pain
Two studies by Mogil and colleagues assessed the differences
in experimental pain models among inbred mouse strains. Using
assays for thermal pain, mechanical pain, chemical pain, and
neuropathic pain, the investigators observed a unique profile
of responsiveness for each different mouse strain. In other
words, each mouse strain with a unique genetic make-up responds
to each type of pain (for instance, heat vs. nerve injury)
in a different manner. The authors conclude that this animal
data suggests potentially important avenues for better understanding
pain in humans.
Mogil JS et al. Heritability of nociception I: Response of
11 inbred mouse strains on 12 measures of nociception. Pain
1999; 80:67-82.
Mogil JS et al. Heritability of nociception II: 'Types' of
nociception revealed by genetic correlation analysis. Pain
1999; 80:83-93.
Editor's
Note: These fascinating studies address the potential importance
of genetic factors in the human conditions of chronic pain.
Why do some people with diabetic neuropathy develop pain and
others do not? Why do some people develop postherpetic neuralgia
following acute herpes zoster while most do not? It has been
shown that some people are genetically predisposed to certain
medical conditions (such as diabetes and migraine), so too
may some possess certain genes that make them susceptible
to chronic pain disorders. Future research is definitely warranted.
Assessment of Diagnostic Criteria for Complex Regional
Pain Syndrome (CRPS)
A multicenter study evaluated the current criteria for the
diagnosis of Complex Regional Pain Syndrome (CRPS), prior
called "reflex sympathetic dystrophy." The results
of this study suggest that these criteria are too vague and
result in the over-diagnosis of this condition. The study
also revealed (as in prior studies) that motor/movement problems
are common to CRPS and help differentiate this condition from
other chronic pain disorders. The authors' proposed a modified
research diagnostic criteria:
|
1.
|
Continuing
pain which is disproportionate to any inciting event |
|
2.
|
Must
report at least one symptom in each of the four categories:
|
Sensory
Vasomotor
Sudomotor/edema
Motor/trophic
|
3.
|
Must
display at least one sign in two or more of the following
categories: |
Sensory
Vasomotor
Sudomotor/edema
Motor/trophic
Bruehl S et al. External validation of IASP diagnostic criteria
for Complex Regional Pain Syndrome and proposed research diagnostic
criteria. Pain 1999; 81:147-154.
Editor's
Note: This study is the first large multisite study scientifically
assessing the CRPS criteria that were developed by a group
of expert clinicians and scientists. Importantly, these criteria
were developed with the hope that they would evolve and be
improved upon by studies like this one. The goal of diagnostic
criteria (particularly in medical conditions where a laboratory
test cannot definitively make the diagnosis, as is the case
with most medical disorders) is to be able to diagnose CRPS
based on the patient's medical history, symptoms and signs
(what a doctor finds on the physical examination) with accuracy,
that is, statistically distinguish it from other types of
neuropathic pain disorders. The results of this study suggest
improvements can be made to the existing criteria, as noted
above.
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