Analgesia
A new analgesic
method:
two-minute sciatic nerve press,
for immediate pain relief
– a randomised trial
Current analgesics have drawbacks such as delays in acquisition, lag-times for effect, and side effects. Jiman He, Bin Wu, Xianrong Jiang, Fenglin Zhang, Tao Zhao and Wenlon Zhang recently presented a preliminary report of a new analgesic method involving a two-minute sciatic nerve press, which resulted in rapid and short-term relief of pain associated with dental and renal diseases. This study investigates whether this technique is effective for pain associated with other disease types, and whether the relief is effective for up to one hour.
BACKGROUND
Human beings have long
suffered from pain caused by
diseases. In medicine, pain is
one of the most common
reasons for patients to seek
care. Analgesics used in
current practice have drawbacks such as delays in acquisition
and lagtimes for effect
after administration. In addition,
many commonly used
analgesics have considerable
side-effects[1-4]. Many non-drug
analgesic interventions have
been used to help manage pain,
including acupuncture,
cryoanalgesia, transcutaneous
electrical nerve stimulation
(TENS), exercise, and music
therapy, etc.[5-7]. Though literature
reviews document the efficacy
of some non-drug analgesic
interventions[5, 8, 9], their
use are usually restricted to
some pain centres, and, the
clinical effectiveness of some
analgesic methods are controversial[
10-12]. We recently
published a preliminary report
on a new analgesic method, a
2-min sciatic nerve press,
which immediately relieved
pain brought on by various
dental and renal diseases[13].
The technique is simple, can
be used any time, any place,
immediately upon the onset of
pain (including outside of a
hospital setting). No side
effects have yet been seen. The
present study examined
whether the technique worked
on more pathologies, and
whether pain relief extended
to up to one hour.
METHODS
Setting and procedures
The study was a randomised,
single-blinded, placebocontrolled,
parallel-group trial
consisting of 135 patients
treated between October 2005
and May 2006 at four hospitals
in China. The study was separately approved by each participating
hospital - Anhui
Province Hospital, Hefei,
230001, China (Approval
date-June 2, 2005); Maanshan
People Hospital, Maanshan,
243000, China (Approval
date- May 20, 2005); Tongling
Count Hospital, Tongling
Count, 244100, China
(approval date-October 18,
2005), and Chuzou Zhongxiyi
Hospital, Chuzou, 239000,
China (approval date-May 28,
2005). Written informed
consent was obtained from
each participating patient.
Patients were divided into
“sciatic press” and “placebo
press” groups. Instructions and
explanations were equally
provided to all patients.
Patients were informed that
the experiments were designed
to test whether the methods
were effective for pain relief.
Patients were advised that they
could discontinue participation
in the study at any time
without penalty, and that their
healthcare treatment would
not otherwise be affected.
After informed consent was
obtained, the participating doctor(s) or assistants taught
the patients how to evaluate
pain using a visual analogue
scale (VAS), where pain
scored from “0” for no pain, to
“10” for most pain. Thereafter,
randomisation of patients to
the “sciatic press” or “placebo
press” group was performed
using the method of Random
Permuted Blocks. The three
stages of the test were then
described to each patient:
baseline pain rating, 2 min of
leg pressure while lying down,
and post-pressure pain rating at
the specified times. Two test
designs were used. For
Emergency patients, pain was
rated once after pressure application.
In contrast, renal,
dental and tumour patients
underwent the 60 min test in
which pain was rated at 10-
min intervals for a period of
one hour after pressure application.
In this context, the ‘0 min’ point indicated the time
at which the 2-min leg pressure
stopped and the post-pressure
pain rating stage commenced.
The baseline pain rating and
leg pressure stages were identical
for the two types of tests.
The positions of sciatic
nerve pressure and the fist
gesture used for pressure application
are shown in Figure 1.
This manipulation technique
has been previously described
in detail[13]. Briefly, 2 min of pressure with the dorsal, proximal phalangeal surface of the
fists (not the knuckles or finger
tips) was applied simultaneously
to the sciatic nerve sites
or the placebo location on
both legs. For the “sciatic
nerve press”, 11 to 20 kg of
pressure was applied to the
sciatic nerves on the back of
the thighs with each fist, while
patients lay prone. For the
“placebo press”, the same pressure
was applied to a parallel
spot on the front of the thighs,
while patients lay supine.
Patients then stood and
rated their pain using a visual
analogue scale table. The
amount of force applied within
the range of 11-20 kg
depended on the patient body
type, with heavily muscled
large-bodied patients receiving
higher pressures than thin
patients. Doctors learned the
pressure force applied by
repeatedly pressing on a
weighted balance.
PARTICIPANTS
The inclusion criterion was
any patient who was feeling
pain during a clinic visit to the
Emergency room, Renal,
Dental, or Oncology Clinics.
Exclusion criteria were age less
than 15 years, emotional instability,
or administration of
another analgesic within 12
hours of the test. For enrolled
patients, the dental diseases
included acute pulpitis and
periapical abscesses. The renal
diseases included infections
and/or stones, and the tumours
included those of the nose,
breast, stomach, and liver.
While Emergency Room
enrollees had various pathologies.
No patients had previously
been treated with the
sciatic press method. For
tumour patients, analgesics
were discontinued 11-13 hours
prior to the test, and the study
began when patients reported
they had moderate-to-severe
pain. The patient groups and
characteristics are shown in
Table 1. Of the 229 solicited
patients, 57 refused to join and
37 were considered ineligible,
leaving 135 patients aged from
15 - 80 years to participate in
the study. Of those 135, two
renal patients in the placebo
group withdrew in the middle
of the 60 min test stating that
the pain was too severe to
continue.
Statistical analysis
Renal, dental and oncology
patients were analysed as one
group in terms of relief of pain.
Emergency room patients were
analysed separately, and
without pathology categorisation.
The baseline VAS scores
and age of the participants
were compared between the
“sciatic press” and “placebo
press” groups using ttests.
Categorical data were analysed
using chi-square, or Fisher
Exact tests. In terms of pain
relief, changes from baseline
were assessed using paired ttests
for both groups.
Comparisons with the
“placebo press” groups were
performed using an analysis of
covariance procedure, with adjustment for baseline VAS
score, gender and age. All tests
were two-sided, and a p-value
of <0.05 was considered to
indicate significance. All
statistical analyses were
performed using SPSS statistical
software (release 13.0).
RESULTS
The study included 95
Emergency Department
patients with various painrelated
conditions (Figure 2).
Following application of the
“sciatic press” technique,
patients recorded a 43.5%
decrease in the mean VAS
pain scores (p<0.001). The
pain relief was significantly
greater than with the “placebo
press” (p<0.001). Notably,
over 70% of Emergency
patients reported pain relief
after the “sciatic press”.
To test the longer-term effectiveness
of the “sciatic press”
method, 40 patients with pain
from tumours, dental and renal
diseases were tested for a
period of one hour (Figure 3).
Pain data for the three patient
groups were pooled, and
demonstrated that mean VAS
scores were lower at all time
points (p<0.001) for the
“sciatic press” group compared
to the placebo group (Figure
3A).
Pain was reduced by
54.5% at the 10th minute, and
by 35.3% at the 60th minute.
In the “placebo press” group,
the VAS score was reduced by
11-15% within the first 10
min, and by 23.4-29.5%
between the 40th and 60th
minutes. Data were also
expressed by subtracting
“placebo press” values from
“sciatic press” values and plotting
the resultant value against
time (Figure 3B). The analysis
showed that the peak pain
relief of this technique
occurred at 10th - 20th
minutes, with relief reduced
47% by the 60th minute.
DISCUSSION
Mechanical pressure can cause
nerve abnormalities. A number
of studies have reported the
effect of pressure on nerves
using different force levels and
time periods of up to several
weeks[14-21]. In animal models,
pressure studies usually involve
surgically exposed nerves[16, 17, 22].
However, the present method
uses a much shorter time
period, two minutes for the
pressure on the intact skin.
Thus far, the method has been
applied to over 600 subjects across 10 hospitals and universities,
and there have been no
reports of adverse side effects.
The type of acute pressure
applied in this technique (11 –
20 kg by each fist (150 – 380
mmHg) for up to 2 min) is not
uncommon in daily activities,
especially for people involved
in sports or heavy manual labour. However, nerve injuries
as a result of this procedure
remain a possibility, and must
be taken into account in future
studies. The present technique
does not involve chronic pressure
on nerves, of which even a
very small amount could cause
severe nerve dysfunction. For
example, chronic pressure on
the sciatic nerve by internal
tension of the obturator muscle
or through anatomical abnormalities
in the piriformis muscle
could cause pain[23-26]. Surgery to
relieve the muscle pressure
results in immediate pain
relief[23, 26-28].
The present study was
single-blinded rather than
double-blinded as the method
is highly effective for pain
relief, and doctors could easily
identify the placebo or the
active treatment during the
test. After patients reported
pain scores, patients themselves
recorded their pain
assessments on a VAS table, or
in some cases, had the doctors
record the VAS score.
However, it would be a
stronger study to have
employed a blinded observer,
which we will include in our
future studies. To our knowledge,
no clinical studies have
reported on the use of pressure
stimulation of the anterior or
posterior thigh area for pain
relief. The study design
ensured no patients had previously
undergone this technique,
and we believe the
‘blinding’ procedures remained
secure during testing. The
pressure of 11 - 20 kg with each fist was chosen based on pilot
studies using Chinese patients.
Such a pressure range may
differ for Western populations
given the difference in average
body size.
The present study showed
that Emergency patients had a
mean baseline VAS score of
7.2, and that the “sciatic press”
resulted in a 43.5% reduction
in pain. Nearly 30% of these
patients reported no pain
relief. Similarly, our previous
study showed that renal
patients had a mean baseline
VAS score of 7.7, that the
sciatic press method resulted in
a 52.2% pain reduction, and
that 40% of renal patients felt
no pain relief[13]. The previous
study also showed that dental
patients had a baseline VAS
score of 6.4, and that the treatment
resulted in a 66.4%
reduction in pain[13], and these
are similar results to those from tumour patients who had a
baseline VAS score of 5.8 and
pain reduction of 70.7%
(tumour patient test data are
not shown in the present
report). These data suggest
that the analgesic effect may
correlate with the baseline
pain score. However, the
present study was not comprehensive enough to make such a
statistical connection, and this
hypothesis awaits further
testing in future larger studies.
In the “placebo press” group
undergoing the 60 min test,
VAS scores decreased
markedly in later time periods
(23.4-29.5% between the 40th
and 60th min) compared to
the first 10 min (11-15%
reduction). In this group, 25%
of patients had pain at the
early time points but not at
later times. For this study
setting, we cannot rule out the
total or partial contribution of
a placebo effect, or some anterior
nerve stimulation to the
late drop. Pain discontinuity
could also be contributing
partially.
Stimulation of peripheral
nerves elevates the pain
threshold[29-32]. According to the
Gate Control Theory of Pain[33],
stimulation of large-diameter
afferent fibres can inhibit the
transmission of nociceptive
information from the dorsal
horn to higher brain centres.
This inhibition occurs rapidly
and is thought to involve the
wide dynamic range (WDR)
neurons[34-36]. The resulting analgesic
effect is considered to be a
short-lasting, segmental inhibition
of pain[37-39]. This theory
may explain the rapid pain
relief observed in some situations.
However, the pain relief
created by the present method
is not limited to the segmental
level, but occurs throughout the
body. Also, significant pain
relief lasted for 60 minutes.
These observations suggest
possible activation of multiple
inhibitory systems. Another
mechanism possibly involved
is activation of the endogenous
opioid system. Yao found
that low frequency stimulation
of the rat sciatic nerve
increased the pain threshold
by 50%, and that this effect
was antagonised by Naloxone
which suggested activation of the opioid system[40].
Pinch press of the rat sciatic
nerve with a vascular clip
(pinch force 120 g) caused
attenuation of WDR neuron
responses to various innocuous
and noxious stimuli[41]. While
the WDR neuron response to
superficial peroneal nerve stimulation
was shown to increase in
cats when the sciatic nerve was
under a clip pressure with a
pinch force 180 g, the response
was inhibited when using low
frequency stimulation (0.2
Hz)[32]. In the present clinical
study, despite it being likely that
there were slight variations in
the pressure location and pressure
force applied, pain relief
was consistently achieved in all
test groups. The current findings
are similar to those from our
pilot studies in which mechanical
pressure was applied at
different locations along the
sciatic nerves using methods
other than fists (data not
shown).
Conclusions
Two minutes of pressure on both
sciatic nerves can produce
immediate and significant
conduction analgesia. This
procedure provides a convenient,
safe and powerful method
for the short-term treatment of
clinical pain induced by diverse
disease types.
The Authors
Jiman He – Biomedicine (TC),
Chinese Academy of Sciences,
Beijing, 100080 China &
Rhode Island Hospital, Brown
University, RI 02903 USA
Bin Wu – Renal Department, Anhui Province Hospital,
Anhui Medical University,
Hefei, 230001 China
Xianrong Jiang – Department
of Biology, Hefei Teachers
College, Hefei, 230061 China
Fenglin Zhang – Department
of Oncology, Maanshan People
Hospital, Maanshan, 243000
China
Tao Zhao – Department of
Emergency, Anhui Province
Hospital, Hefei, 230001 China
Wenlon Zhang – Department
of Dentistry, Chuzou Zhongxiyi
Hospital, Chuzou, 239000
China
Email addresses:
J H: jiman_he@brown.edu
(corresponding author)
BW: wubin@ahmu.edu.cn
X J: hxh5639@sina.com
F Z: zhangfenglin@csco.org.cn
T Z: zhaotaoyin@163.com
WZ: wenlonzhang@sohu.com
Competing interests
The authors declare that they
have no competing interests.
CREDIT
The original version of this
article is published online here:
http://www.biomedcentral.com/1471-2253/8/1
© 2008 He et al., licensee BioMed Central Ltd.
References
References for this article can be
found with the online version.
REFERENCES
References are available with original online version of this article
http://www.biomedcentral.com/1471-2253/8/1
Date
of upload: 3rd April 2008
