WHAT'S
NEW -- September 1999
"Breakthrough
Pain" Is An Important Clinical Problem in Cancer Pain
This cross-sectional survey assessed the quality and impact
of breakthrough pain in 164 inpatients with cancer (breakthrough
pain is severe pain flares that occur in the setting of a
tolerable background pain usually being treated with opioids
in cancer patients). Approximately one-half (51%) of these
patients had experienced at least one episode of breakthrough
pain the previous day, with the average number of six breakthrough
pain episodes (but with a range of 1 to 60 episodes in the
day prior). These breakthrough pain episodes were unpredictable
in 78% of cases, although 62% could identify precipitating
factors, such as movement or their pain medication wearing
off. Patients who did experience breakthrough pain had more
severe pain syndromes than those who did not have breakthrough
pain; breakthrough pain patients had statistically more intense
and frequent background pain, greater pain-related functional
impairment, worse mood, and more anxiety.
Portenoy RK, Payne D, Jacobsen, P. Breakthrough pain: characteristics
and impact in patients with cancer pain. Pain 1999;
81:129-134
Editor's
Note: This important study provides further evidence that
breakthrough pain is an important clinical issue in many patients
suffering from cancer pain. Not only did patients with breakthrough
pain have overall more pain, but also these patients suffer
from more functional disability and psychological disturbances
than do those cancer pain patients without breakthrough pain.
As Dr. Portenoy and his colleagues write: "The findings
suggest the need for further studies of breakthrough pain
and more effective therapeutic strategies."
 
Topical Capsaicin Causes Degeneration of Nerves in the
Skin
This study aimed to quantify both the loss of sensation and
the changes in peripheral nerve pathology in the skin being
treated with capsaicin. Capsaicin (0.075%) was applied to
normal persons' forearms four times daily for 3 weeks. All
sensations tested, light touch, cold, and heat, were reduced
by capsaicin. As early as 3 days after the start of treatment
there was a significant (74%) decrease in the amount of nerve
fibers in the underlying skin and after 3 weeks of capsaicin
there was an 82% reduction. Six weeks after the capsaicin
treatment was stopped there was a return to normal sensation,
except cold, and there was evidence of nerve regeneration.
Nolano M, Simone DA, Wendelschafer-Crabb G, Johnson T, Hazen
E, Kennedy WR. Pain 1999; 81:135-145
Editor's
Note: Topical capsaicin for the treatment of chronic neuropathic
pains, such as postherpetic neuralgia and diabetic neuropathy,
has fallen out of favor by most pain specialists because it
rarely results in significant pain relief and, in many patients,
capsaicin treatment worsens the pain. This important study
has demonstrated that capsaicin can actually cause nerve degeneration
and thereby result in loss of sensation. The findings of this
study also "demonstrate that ENF's (epidermal nerve fibers)
are involved in conveying the pain sensation evoked by noxious
heat and mechanical stimuli." In other words, dysfunctional
superficial nerves in the skin may be a clinically important
source of pain in some chronic pain conditions.
Does
Pain Perception Vary Depending on the "Time of the Month?"
This important review article evaluated whether women's pain
perception (in experimentally induced pain studies) varies
depending on when in their menstrual cycle the study is performed.
The authors reviewed and statistically analyzed (by meta-analysis)
16 published studies. They found higher pain thresholds occur
during the follicular phase, that is the interval from the
onset of menses to ovulation, as compared to luteal phase
(interval from ovulation to the onset of menstrual bleeding).
Riley JL, Robinson ME, Wise EA, Price DD. A meta-analytical
review of pain perception across the menstrual cycle. Pain
1999; 81:225-235
Editor's
Note: This study demonstrated that pain perception among normal
females changes during their menstrual cycle. It has been
shown that sex hormones can influence the effects of endogenous
opioids, that is the body's natural painkillers such as endorphin.
Also it is known that female hormonal fluctuations affect
core body temperature which can alter the amount of pain perceived.
However, as the authors point out: "This paper raises
several important questions, which yet are to be answered."
For instance, how do these changes during the menstrual cycle
affect patients with chronic pain conditions? What implications
do these variable pain thresholds during the menstrual cycle
have for clinical trial studies? Thus, the issue of pain and
the female menstrual cycle has important implications in the
care of patients in pain and also may have important effects
on the results of clinical studies.
Cluster Headache -- Anxiety, Memory, and the Brain
The investigators of this study compared episodic cluster
headache and tension type headache patients' anxiety and memory
by using semi-structured interviews, validated psychiatric
scales, and neuropsychological tests. They found that patients
with cluster headache had a higher frequency of anxiety disorders
(Panic Disorder and Generalized Anxiety Disorder) than did
those with tension type headache. Also, cluster headache patients
demonstrated a selective problem only with their verbal memory.
The authors concluded that such findings may suggest cluster
headache patients may have a "functional disruption" within
the temporal lobe of the brain.
Jorge RE, Leston JE, Arndt S, Robinson RG. Cluster headaches:
Association with anxiety disorders and memory deficits. Neurology
1999; 53:543-547
Editor's
Note: It has been known for quite some time that patients
who suffer cluster headache tend to become extremely anxious
during a cluster headache attack. Other studies have shown
that this anxiety appears to be "organic", that is due to
an abnormality in the brain as a part of the overall cluster
syndrome and is not due to the severe pain itself. Thus the
findings of this study, especially the selective verbal memory
problems, provide more evidence of a possible brain dysfunction
as an underlying cause of cluster headache.
Acupuncture
and TENS Improve Chronic Back Pain
This study compared acupuncture and transcutaneous nerve stimulation
[TENS] in 60 elderly patients with low back pain of at least
6 months duration. (Acupuncture consisted of treating points
chosen per individual patient with two 20-minute sessions
per week for 4 weeks and TENS consisted of home treatment
for 4 weeks with electrode placement and stimulation intensity
individualized per patient). Both therapies were provided
by the same physiotherapist. All patients in this study, whether
they received acupuncture or TENS, significantly improved
in their pain scores and ingested less pain tablets upon completion
of the 4 weeks of treatment and at 3-month follow-up. Interestingly,
there was even a trend of further improvement in the acupuncture
group 3 months after treatment ceased.
Grant DJ, Bishop-Miller J, Winchester DM, Anderson M, Faulkner
S. A randomized comparative trial of acupuncture versus transcutaneous
electrical nerve stimulation for chronic back pain in the
elderly. Pain 1999; 82:9-13.
Editor's
Note: As the investigators wrote, a 'placebo response' cannot
be discounted as a potential reason for improvement. However,
even if there were a 'placebo response' the impressive results
cannot be overlooked, especially since these therapies do
not have any potentially serious side effects or complications.
Chronic low back pain can be refractory to most drugs and
nerve blocks, which can cause intolerable side effects. Thus,
this study provides further evidence that there IS a role
for the benign treatments of acupuncture and TENS in the treatment
of some chronic pain states.
Please visit our redesigned homepage.
|
