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Effect of lumbar spinal manipulation on local and remote pressure pain threshold and pinprick sensitivity in asymptomatic individuals: A randomised trial

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Background The mechanisms of clinical pain relief associated with spinal manipulative therapy (SMT) are poorly understood. Our objective was to determine whether lumbar high-velocity low-amplitude SMT altered pressure pain threshold (PPT) and pinprick sensitivity (PPS) locally and remotely, how long any change lasted (up to 30 min), and whether changes related to the side of SMT. Methods Thirty-four asymptomatic participants (mean age 22.6 years ±4.0) received a right- or left-sided lumbar SMT. PPT and PPS were measured bilaterally at the calf, lumbar spine, scapula, and forehead before and immediately, 10, 20, and 30 min after intervention. Data were collected between October 2014 and June 2015. Results Bilateral calf and lumbar spine PPT increased significantly after 10 – 20 min and was maintained at 30 min (7.2–11.8 % increase). PPS decreased significantly in all locations at various times (9.8 – 22.5 % decrease). At the calf and lumbar spine, PPT increased slightly more ipsilateral to the SMT than contralateral. Conclusions Lumbar SMT reduced deep pressure sensitivity locally and in the lower limbs for at least 30 min, whereas sensitivity to pinprick was reduced systemically. These findings suggest that SMT specifically inhibits deep pressure sensitivity distally. These findings are novel compared to other lumbar SMT studies, and may reflect a local spinal or complex supraspinal analgesic mechanism.
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R E S E A R C H Open Access
Effect of lumbar spinal manipulation on
local and remote pressure pain threshold
and pinprick sensitivity in asymptomatic
individuals: a randomised trial
Sasha L. Dorron
1*
, Barrett E. Losco
1
, Peter D. Drummond
2
and Bruce F. Walker
1
Abstract
Background: The mechanisms of clinical pain relief associated with spinal manipulative therapy (SMT) are poorly
understood. Our objective was to determine whether lumbar high-velocity low-amplitude SMT altered pressure
pain threshold (PPT) and pinprick sensitivity (PPS) locally and remotely, how long any change lasted (up to 30 min),
and whether changes related to the side of SMT.
Methods: Thirty-four asymptomatic participants (mean age 22.6 years ±4.0) received a right- or left-sided lumbar
SMT. PPT and PPS were measured bilaterally at the calf, lumbar spine, scapula, and forehead before and
immediately, 10, 20, and 30 min after intervention. Data were collected between October 2014 and June 2015.
Results: Bilateral calf and lumbar spine PPT increased significantly after 10 20 min and was maintained at 30 min
(7.211.8 % increase). PPS decreased significantly in all locations at various times (9.8 22.5 % decrease). At the calf
and lumbar spine, PPT increased slightly more ipsilateral to the SMT than contralateral.
Conclusions: Lumbar SMT reduced deep pressure sensitivity locally and in the lower limbs for at least 30 min,
whereas sensitivity to pinprick was reduced systemically. These findings suggest that SMT specifically inhibits deep
pressure sensitivity distally. These findings are novel compared to other lumbar SMT studies, and may reflect a local
spinal or complex supraspinal analgesic mechanism.
Trial registration: Registered with the Australian New Zealand Clinical Trials Registry (ACTRN12614000682640).
Keywords: Spinal manipulative therapy, Lumbar spine, Pain sensitivity, Pressure pain threshold, Pinprick sensitivity
Background
Spinal manipulative therapy (SMT) is a manual therapy
technique used by various health care professions
including chiropractors, osteopaths and physiotherapists
[1]. Evidence is mixed but some studies suggest that
SMT may be effective in managing non-specific spinal
pain and some types of headache [27]. Since musculo-
skeletal conditions, particularly low back pain (LBP),
represent a significant economic burden and affect a
substantial proportion of the population [8, 9], improv-
ing our management of these conditions is important.
There is a lack of evidence to explain how SMT may
achieve positive clinical outcomes such as pain relief.
Improving our understanding of the neurophysiological
effects of SMT may improve its clinical use and allow
practitioners to make better choices about when and
where to apply SMT.
Pressure pain threshold (PPT) is a widely used form of
experimental pain, which represents the amount of
mechanical pressure required to elicit a nociceptive
response at the testing site. It is thought deep Aδand C
sensory fibres are activated at the PPT [1012].
Pinprick sensitivity (PPS), on the other hand, is not
widely used in manual therapy research, and is measured
by the self-reported pain response to a sharp stimulus to
* Correspondence: s.dorron@murdoch.edu.au
1
Discipline of Chiropractic, School of Health Professions, Murdoch University,
90 South Street, Murdoch, WA 6155, Australia
Full list of author information is available at the end of the article
© 2016 The Author(s). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Dorron et al. Chiropractic & Manual Therapies (2016) 24:47
DOI 10.1186/s12998-016-0128-5
the skin. PPS is a superficial nociceptive response
mediated by Aδfibres [10, 12].
The short-term effect of SMT on various forms of
experimental pain has been studied previously, but many
gaps remain. Two recent systematic reviews concluded
that SMT has an overall effect of increasing PPT (redu-
cing sensitivity) at sites local to the SMT and remotely
[13, 14]. The remote effect may be regional [15, 16] (at a
peripheral site innervated by the target spinal region) or
systemic [1720]. SMT also appears to reduce sensitivity
to other types of experimental pain [13, 14]. Curiously,
PPT increases after cervical SMT but this change has
not been shown after lumbar SMT [2126]. The reason
for this is unknown and seems biologically questionable.
It could reflect widely differing methods that may have
affected the outcomes. The effect of SMT on PPS is
unknown. The literature on this topic was considered
sufficiently weak to justify further investigation.
ThedurationofchangetopainsensitivityfollowingSMT
is also unknown as, in the few studies that have collected
data beyond 10 min, findings are mixed [15, 16, 27, 28].
Reductions in pain sensitivity appear to be bilateral
[2933], but there may be asymmetry related to dominant
side [31, 32] or side of SMT [29, 30, 33].
Aims
This research aimed to investigate the effects of lumbar
SMT on PPT and PPS, locally and remotely, for 30 min
following SMT, and the effects of SMT on the unilateral
compared to contralateral side of the body. We were
interested in determining whether lumbar SMT had a
hypoalgesic effect that was selective to certain stimuli, or to
certain regions or sides of the body. Our additional aim was
to delineate the short-term time course of any change.
Methods
This study was a single-blind two-arm randomised trial,
and was approved by the Human Research Ethics
Committee of Murdoch University (permit 2014/141).
Participants
Asymptomatic participants aged 1845 years were
recruited from the Murdoch University campus (Perth,
Western Australia), via in-class announcements and
flyers, and from the general public via word of mouth.
Participants were excluded if any of the following
applied: (a) current chronic pain condition anywhere, (b)
current acute or sub-acute LBP, (c) contraindication to
lumbar SMT, (d) qualified chiropractor or student in 4
th
or 5
th
year of chiropractic university degree (presumed
to be more likely to introduce expectancy bias due to
prior knowledge of the neurophysiology of SMT), (e)
taken pain-relieving medication in the preceding 24 h,
(f) had alcohol within the preceding 12 h.
Originally, an inclusion criterion of naivety to spinal
manipulation was included. However, significant diffi-
culty with recruitment led us to remove this and instead
add exclusion criterion (d), above.
Outcome measures
Pressure pain threshold
PPT, as a measure of deep mechanical pain sensitivity,
was measured using an algometer (FDIX, Wagner
Instruments, USA) with a 1 cm
2
rubber probe. The alg-
ometer was validated and standardised against a Kistler
Force Plate prior to use in this study (Pearsons r = 0.99,
p= .01). For measurement, the algometer was placed
perpendicular to the skin and pressure was increased at
a rate of 500 g/cm
2
per second, monitored real-time on
the digital algometer display by the assessor. The partici-
pant was asked to say Yeswhen the sensation of pres-
sure first changed to pain, at which point the algometer
was removed and the maximum pressure recorded.
Single measurements at each site were taken following a
standard pattern, repeated three times to obtain three
measurements per site. This validated approach allowed
sufficient rest time between measures at each site [34, 35].
We used a cut-off point of 10 kg/cm
2
for the forehead and
scapula [36], and 12.5 kg/cm
2
for the lumbar and gastro-
cnemius sites as this was the upper limit of the algometer.
If the cut-off was reached, the cut-off value was used as
the measurement for that site and the algometer removed.
The average of the second and third measures was used
for analysis [36]. An increase in PPT represents a decrease
in sensitivity.
Pinprick sensitivity
PPS, as a measure of superficial pain sensitivity, was
measured using the Neuropen with Neurotips (Owen
Mumford, UK). This device is designed to consistently
exert 40 g of force when pressed into the skin, though
no reliability studies were found for its use. An 11-point
Numerical Rating Scale (NRS) was used where 0 = not
sharp, and 10 = extremely sharp, as used previously in an
experimental trial [37]. The device was placed perpen-
dicular to the skin and pressed in until the guiding
markers were aligned; this was maintained for one
second and then removed. The participant was then
asked to verbally report the intensity of the sharpness
using the NRS. Measurements were performed once at
each site, immediately following the completion of PPT
measures. A new tip was used for each participant. A
decrease in PPS represents a decrease in sensitivity.
Interventions
A high-velocity low-amplitude SMT was targeted at the
L5-S1 spinal segment. A commonly used SMT tech-
nique, referred to as the hypothenar mammillary push
Dorron et al. Chiropractic & Manual Therapies (2016) 24:47 Page 2 of 9
[38], was used (Fig. 1). The participant was placed in a
side-lying position, with the upper leg bent and the
lower leg straight. The researcher stabilised the partici-
pant at the shoulder with their cephalad hand, and at
the thigh with their own leg. A manual contact with the
researchers caudal hand was then taken over the L5
mamillary process on the right or left side (allocated
randomly), the joint was taken to pre-tension, and a
high-velocity low-amplitude thrust delivered targeting
the L5-S1 facet joint in a posterior to anterior direction.
If the clinician thought that the first SMT was unsuc-
cessful, he was allowed to perform a second SMT. The
absence of a facet joint cavitation (audible release)
during the SMT was not considered sufficient alone to
attempt a second SMT, as there is no evidence that a
cavitation is a necessary component of a successful
manipulation [3941].
Procedure
Participants attended a single session at Murdoch
University campus, where they completed intake forms,
read an information letter, and completed informed
consent. Individual participants were given two practice
attempts for each outcome measure, applied to the hand,
to familiarise them with the procedure. The following
four locations were then marked bilaterally on the skin
with a non-permanent marker: (a) infraspinatus muscle
belly, 2 cm lateral and interior to the root of the spine of
the scapula, (b) 2 cm lateral to the L5 spinous process
over the paraspinal muscles, (c) mid-portion of the
medial gastrocnemius muscle belly, (d) frontal eminence
of the forehead. Baseline outcome measures were taken,
PPT being measured before PPS, and the assessor then
left the room to remain blind to which side SMT was
applied. The researcher performing the intervention, a
registered chiropractor with 15 years clinical and
academic experience, randomised participants into one
of two groups using the GraphPad random number
generator [42] to generate a 1:1 list of 1s and 2s, which
were placed into sequentially numbered, sealed, opaque
envelopes. The envelope was opened immediately prior
to the intervention based on order of enrolment into the
study. After the intervention was administered, the
assessor re-entered the room and measured outcomes
immediately, at 10, 20, and 30 min.
Power analysis
A power analysis using G*Power 3.1 software (University
of Düsseldorf, Germany) showed that a sample size of
34 would provide 80 % power for detecting a large effect
size of 0.4.
Data analysis
Data were analysed using SPSS Version 23. A repeated-
measures analysis of variance was conducted for PPT
and PPS at each location, using factors of time (baseline,
immediate, 10, 20, and 30 min), side (side of measure-
ment), and group (side of manipulation, where right
SMT = R-SMT and left SMT = L-SMT). Simple contrasts
between baseline and each subsequent time point were
included in the analyses. Further interactions were inves-
tigated using paired t-tests. Effect sizes are reported as
partial Eta squared (ƞ
P
2
), where 0.10, 0.25, and 0.50
are considered to represent small, moderate, and large
effect sizes respectively [43].
Results
Thirty-four participants (20 male) were recruited for
data collection and included in analysis (Fig. 2), with a
mean age of 22.6 years (±4.0, range 1836). Data were
collected between October 2014 and June 2015, ending
when 34 participants with usable data completed the
trial. Baseline characteristics, including PPT and PPS
values, are reported in Table 1. No harms were reported
during or after follow-up. The intervention was consid-
ered successful in all cases at the first attempt; thus, no
participant received a second SMT.
Pressure pain threshold
Significant effects over time were observed for calf (p=.03,
ƞ
P
2
= .09) and lumbar spine PPT (p= .003, ƞ
P
2
= .15) with
weak effect sizes. Contrasts between baseline and subse-
quent time points revealed significant increases in PPT
from baseline to 20 and 30 min at the calf, and from
baseline to 10, 20 and 30 min at the lumbar spine (Table 2,
Fig. 3). There was no effect over time for PPT at the scapula
(p=.71,ƞ
P
2
=.01) or forehead (p=.67,ƞ
P
2
= .01).
Significant effects were observed for side at the calf
(p= .001, ƞ
P
2
= .32) and lumbar spine (p=.01, ƞ
P
2
=.21)
with moderate and weak effect sizes respectively. In par-
ticular, PPT was higher on the right compared to the left
at both the calf (5.4 kg/cm
2
and 4.8 kg/cm
2
respectively)
and lumbar spine (7.1 and 6.7 kg/cm
2
respectively). There
was no difference between sides at the scapula (p=.87,
ƞ
P
2
= .001) or forehead (p=.64, ƞ
P
2
=.01).
Fig. 1 Right L5-S1 SMT technique
Dorron et al. Chiropractic & Manual Therapies (2016) 24:47 Page 3 of 9
No significant differences were detected between
groups including across time and side for PPT at the
calf, lumbar spine, scapula or forehead.
Pinprick sensitivity
Significant effects over time were observed for PPS at the
calf (p=.01, ƞ
P
2
= .10), lumbar spine (p=.00, ƞ
P
2
=.21),
and forehead (p=.02, ƞ
P
2
= .10), each with weak effect
sizes, but not at the scapula (p=.13, ƞ
P
2
= .05). Contrasts
revealed significant decreases in PPS at the calf between
baseline and 20, and 30 min. At the lumbar spine, signifi-
cant decreases were noted between baseline and immedi-
ate, 10, 20, and 30 min. At the forehead, decreases were
noted between baseline and 10, 20, and 30 min. Despite
no over-all effect for Time at the scapula, contrasts re-
vealed significant decreases from baseline to 10 min, and
20 min (Table 3).
Significant effects were observed for side at the calf
(p= .049, ƞ
P
2
= .12) and forehead (p=.001, ƞ
P
2
=.29) with
weak and moderate effect sizes respectively. In detail, PPS
was found to be higher on the right compared to the left
at both the calf (4.5 and 4.3) and forehead (4.6 and 4.2).
There was no difference between sides at the lumbar spine
(p=.91,ƞ
P
2
= .00) and scapula (p=.63, ƞ
P
2
=.01).
A between-group difference was found at the scapula
(p= .04, ƞ
P
2
= .12) with a weak effect size. In detail, the
L-SMT group had higher overall scapula PPS compared
to the R-SMT group (4.2 and 2.9 respectively). A signifi-
cant side x group interaction at the scapula was also
found (p= .03, ƞ
P
2
= .14) with weak effect size. The data
indicate that in the R-SMT group, right scapula PPS was
lower than the left (2.8 and 3.1 respectively), but this
was reversed in the L-SMT group (4.4 and 4.0 respect-
ively). These likely reflect baseline differences between
groups.
Fig. 2 Data collection flow chart
Table 1 Baseline characteristics
R-SMT L-SMT Actual difference
(% difference)
Gender 8 female,
9 male
6 female,
11 male
-
Mean age, years 22.6 (3.1) 22.5 (4.8) 0.1 (0.3)
Dominant hand 11 right, 6 left 16 right, 1 left -
Calf PPT 5.1 (2.2) 4.5 (1.9) 0.6 (12.2)
Lumbar Spine PPT 7.1 (2.9) 5.9 (2.6) 1.2 (17.3)
Scapula PPT 5.1 (1.9) 4.1 (1.8) 0.9 (18.2)
Forehead PPT 2.8 (1.0) 2.4 (1.0) 0.5 (15.9)
Calf PPS 4.1 (2.2) 5.1 (2.4) 1.0 (19.5)
Lumbar Spine PPS 4.3 (1.6) 5.3 (2.1) 0.9 (17.9)
Scapula PPS 3.2 (1.7) 4.5 (2.0) 1.3 (28.5)
Forehead PPS 4.4 (1.8) 5.3 (2.4) 0.9 (17.3)
Abbreviations:R-SMT right spinal manipulative therapy group, L-SMT left spinal
manipulative therapy group, PPT pressure pain threshold, PPS
pinprick sensitivity
Note: where appropriate, data reported as mean (standard deviation), PPT
reported in kg/cm
2
, PPS on 11-point numerical rating scale
Dorron et al. Chiropractic & Manual Therapies (2016) 24:47 Page 4 of 9
No further significant differences were detected be-
tween groups, including across time and side, for PPS at
the calf, lumbar spine, scapula or forehead.
Ipsilateral vs. Contralateral changes
No significant time x side x group changes were
detected. However, t-tests between baseline and each
subsequent time point indicated that PPT increases were
slightly greater on the side ipsilateral to the SMT in the
calf particularly, and to a lesser extent in the lumbar
spine (see Additional file 1).
Discussion
This is the first study to observe significant increases in
PPT at the lumbar spine and calf following lumbar high-
velocity low-amplitude SMT, and to discover that these
changes appeared to develop over 10 20 min and
persist to 30 min.
PPS, an unvalidated outcome measure, was seen to
decrease over time at all locations. This could be a
systemic real effect or may represent a non-specific
effect such as a learned response or adjustment to
repeated measurement. Both types of pain sensitivity are
mediated by Aδfibres, but PPT additionally involves C
fibres. Since changes in PPT were not systemic in the
present study, a systemic treatment effect on PPS is
considered unlikely. Further research may be warranted
to clarify this.
The magnitude of change in PPT was small, ranging
from 7.2 to 11.8 %. The minimum detectable change for
PPT has not been clearly defined, but is likely between
35 and 50 % [35, 44, 45]. Percentage change is likely to
be most relevant when considering PPT, as absolute
baseline values differ widely between testing sites [45].
Based on these minimum detectable change values, our
changes may be due to measurement error or chance.
The magnitude of changes (as percentage) observed in
the present study are similar to some [28] but smaller
than other studies [19, 46], but falls within the range
identified in the systematic review by Millan et al. [13]
of 4.8 to 44.2 %. In our study, as increases in PPT at the
calf and lumbar spine were gradual and consistent, and
absent at the scapula and forehead, we believe that
lumbar SMT evoked a real but small change in PPT.
We observed some asymmetry between the right and
left sides. The right calf and lumbar spine were less
sensitive overall than the left when measuring PPT, while
the right calf and forehead were more sensitive overall
than the left when measuring PPS. This is probably a
reflection of baseline differences. This finding is at odds
with the literature as others have noted no systematic
differences in PPT between sides of the body or depending
on hand dominance [34, 47, 48]. Our observations may
relate to methodological decisions (the left side was always
measured before the right), or another unknown factor.
Other literature investigating the effect of SMT on
PPT is conflicting. Five studies investigating the effect of
lumbar SMT on PPT have found no significant change
[21, 2326]. Four of these measured PPT only immedi-
ately following SMT [21, 2325], so it is possible they
may have missed an effect that developed over time, as
occurred in our study. The remaining study found a
trend toward increasing PPT but this did not reach sig-
nificance at 30 min [26]. Another study noted, unusually,
a significant decrease in PPT after 10 and 15 min [22].
This study did not have a comparison group, and since a
nerve conduction study was performed immediately
prior to PPT, PPT measures may have been confounded.
The results of studies in the lumbar spine are in stark
contrast to cervical spine literature, which quite consist-
ently demonstrate increases in PPT [16, 19, 2831, 46, 49],
and are in agreement with our own study of the lumbar
spine. Additionally, other studies have demonstrated mech-
anical hypoalgesia following lumbar mobilisation [50, 51],
Table 2 Changes in pressure pain threshold over time
Mean PPT,
kg/cm
2
(SD)
Difference compared
to baseline, kg/cm
2
(% change)
p-value (effect
size), compared
to baseline
Calf
Baseline 4.8 (2.1) - -
Immediate 5.1 (2.2) 0.3 (5.4 %) .11 (.08)
10 min 5.1 (2.2) 0.4 (7.3 %) .05 (.11)
20 min 5.2 (2.2) 0.5 (9.6 %) .02* (.17)
30 min 5.2 (2.0) 0.4 (9.0 %) .03* (.14)
Lumbar spine
Baseline 6.5 (2.8) - -
Immediate 6.7 (2.7) 0.2 (3.7 %) .25 (.04)
10 min 7.0 (2.5) 0.5 (7.2 %) .03* (.13)
20 min 7.1 (2.7) 0.6 (9.2 %) .01* (.19)
30 min 7.3 (2.6) 0.8 (11.8 %) .01* (.21)
Scapula
Baseline 4.6 (1.9) - -
Immediate 4.6 (2.0) 0.01 (0.2 %) .88 (.001)
10 min 4.7 (2.1) 0.1 (2.4 %) .45 (.02)
20 min 4.7 (1.9) 0.1 (2.6 %) .44 (.02)
30 min 4.7 (1.7) 0.1 (2.0 %) .58 (.01)
Forehead
Baseline 2.6 (1.0) - -
Immediate 2.7 (1.1) 0.1 (2.3 %) .40 (.02)
10 min 2.7 (1.1) 0.1 (2.3 %) .45 (.02)
20 min 2.7 (1.0) 0.1 (1.9 %) .58 (.01)
30 min 2.7 (1.0) 0.1 (3.1 %) .34 (.03)
Abbreviations:PPT pressure pain threshold, SD standard deviation, * = p.05.
Note: effect size reported as partial eta squared (ƞ
P
2
)
Dorron et al. Chiropractic & Manual Therapies (2016) 24:47 Page 5 of 9
lending further strength to our findings. The differences in
the literature may relate to methodological differences in
terms of PPT testing sites and study populations. Alterna-
tively, differences in mechanoreceptor and nociceptor
density, in baseline PPT values, or in the neurophysiologic
response to SMT between different spinal regions may
explain the inconsistency in the literature [22].
The duration of change in PPT after SMT is not well
studied. Cervical and thoracic spine studies have observed
increases in PPT at 10 min [19, 20], 15 min [15], 20 min
[28], and 30 min [27]. Others have seen no change at
10 min [52], and 2 h [16]. We demonstrated a small
change that persisted at 30 min.
Studies that have shown a systemic change over time
in PPT following SMT have all failed to show differences
when compared to other active treatments or a control
condition [1720], calling into question whether a
specific systemic response to SMT occurs. This contrasts
with one sham-controlled study [15] and one study
comparing two types of SMT which show only local and
regional changes following SMT [16]. Our findings
suggest that deep mechanical hypoalgesia in response to
lumbar SMT is local and regional, but not systemic.
A recent systematic review found no correlation between
pain thresholds (including PPT) and subjective pain inten-
sity or disability [53]. PPS does not appear to have been
studied in this capacity. It is unknown whether change in
PPT following SMT relates to short- or long-term clinical
improvement, or if the response differs between healthy
and symptomatic populations. Hypothetically, it is possible
that a window of hypoalgesia following SMT could pro-
mote exercise and physical activity in spinal pain patients.
While changes in pain sensitivity following SMT may not
currently translate into clinical recommendations, it still
represents a promising avenue for experimental research
into the neurophysiologic effects of SMT.
Several neurophysiological theories to explain deep
mechanical hypoalgesia following SMT have been proposed.
Fig. 3 Changes in pressure pain threshold over time with standard error bars. Abbreviations: PPT = pressure pain threshold, Base = baseline,
Immed. = immediate, * = p .05 compared to baseline
Dorron et al. Chiropractic & Manual Therapies (2016) 24:47 Page 6 of 9
These include activation of the descending inhibitory
pain control system or activation of the pain gate mechan-
ism [54]. The descending inhibitory pain control system is
able to selectively modulate C-fibre nociceptive signals
[55], which would be expected to affect PPT (mediated by
C- and Aδ-fibres) but not PPS (mediated only by Aδ-
fibres). This system is also capable of acting regionally in
the spinal cord [56], which could explain the local and
regional hypoalgesia we observed. An animal-model
experiment demonstrated that mechanical hypoalgesia
induced by joint manipulation was mediated by the neuro-
transmitters serotonin and noradrenaline, both of which
are involved in the descending inhibitory pain control
system [57]. Thus, activation of the descending inhibi-
tory pain control system may offer a plausible explan-
ation for our findings. The pain gate mechanism is
activated only when there is a concurrent non-nociceptive
stimulus [58] and thus would likely not account for the
more prolonged hypoalgesia we observed. Ultimately,
post-SMT hypoalgesia likely arises from a combination of
neurophysiologic mechanisms, as well as placebo and
psychosocial factors [59].
Strengths and limitations
There are several strengths to the present study. We
followed best practice conditions (based on CONSORT
guidelines), and used an a priori power calculation,
assessor blinding, participants who were unfamiliar with
the neurophysiology of SMT, a single experienced clin-
ician providing interventions, and a validated instrument
for measuring PPT.
There are also various limitations. Firstly, we acknow-
ledge that measuring PPS may have had a confounding
effect on PPT, though PPS was always measured after
PPT and followed by a rest period before the next
follow-up to minimise this possibility. PPS was also an
unvalidated and subjective measure, and participants
individual criterion for sharpness intensity may have
changed with repeated measurement. Next, anxiety is a
known confounder to pain [60], which was not con-
trolled for other than with a thorough informed consent
process and assuring participants that SMT was unlikely
to cause pain. As our study recruited mainly young,
asymptomatic participants, the generalisability of the
results is limited when considering older or symptomatic
Table 3 Changes in pinprick sensitivity over time
Mean PPS, 11-point NRS (SD) Difference compared to baseline, 11-point NRS (% change) p-value (effect size), compared to baseline
Calf
Baseline 4.6 (2.3) - -
Immediate 4.6 (2.1) 0.02 (0.4 %) .94 (.000)
10 min 4.5 (2.4) 0.1 (3.2 %) .51 (.01)
20 min 4.1 (2.2) 0.5 (11.5 %) .04* (.13)
30 min 4.0 (2.2) 0.6 (13.6 %) .02* (.16)
Lumbar Spine
Baseline 4.8 (1.9) - -
Immediate 4.1 (2.1) 0.6 (13.4 %) .003* (.24)
10 min 3.9 (2.3) 0.9 (18.0 %) .001* (.30)
20 min 4.0 (2.0) 0.8 (17.1 %) .001* (.29)
30 min 3.7 (2.2) 1.1 (22.5 %) .000* (.42)
Scapula
Baseline 3.9 (1.9) - -
Immediate 3.6 (2.1) 0.3 (6.7 %) .28 (.04)
10 min 3.4 (1.9) 0.5 (12.4 %) .03* (.15)
20 min 3.5 (2.1) 0.4 (9.8 %) .04* (.13)
30 min 3.5 (2.0) 0.3 (8.8 %) .11 (.08)
Forehead
Baseline 4.8 (2.1) - -
Immediate 4.7 (2.2) 0.1 (2.7 %) .45 (.02)
10 min 4.3 (2.0) 0.5 (10.8 %) .04* (.13)
20 min 4.1 (2.0) 0.7 (14.8 %) .007* (.20)
30 min 4.2 (2.3) 0.6 (13.1 %) .05* (.12)
Abbreviations:PPS pinprick sensitivity, NRS numerical rating scale, SD standard deviation, * = p.05. Note: effect size reported as partial eta squared (ƞ
P
2
)
Dorron et al. Chiropractic & Manual Therapies (2016) 24:47 Page 7 of 9
populations. Additionally, we did not have a sham group
so some of the effects may be explained by placebo or
other non-specific effects such as the positioning or
physical touch, or a learned effect. However, it is difficult
to envision how such effects would be expressed as
regional hypoalgesia. Though participant blinding in
manual therapies is difficult [61], a non-thrust manual
contact group would have been valuable. Finally, though
the study was adequately powered to detect large main
effects, it was likely underpowered to detect small
changes and two-way and three-way interactions involv-
ing side of stimulation or asymmetry of response; thus,
we may have committed some type II errors.
Conclusions
As the only study to date to have demonstrated short-
term deep mechanical hypoalgesia following lumbar
high-velocity low-amplitude SMT, replication of our
results is required before firm conclusions can be drawn.
Future research should be directed at measuring mech-
anical hypoalgesia for at least 30 min following SMT,
and comparing the effects of SMT in different spinal re-
gions on pain sensitivity to determine if there are indeed
differences between regions. Additionally, furthering our
understanding of the neurophysiological pathways that
may be involved is important.
Additional file
Additional file 1: Ipsilateral vs. Contralateral Changes in Pressure Pain
Threshold and Pinprick Sensitivity. Description of data: Data tables and
figures showing comparisons of change in PPT and PPS on ipsilateral and
contralateral sides to SMT. (DOCX 81 kb)
Abbreviations
LBP: Low back pain; L-SMT: Left-sided spinal manipulative therapy;
NRS: Numerical rating scale; PPS: Pinprick sensitivity; PPT: Pressure pain
threshold; R-SMT: Right-sided spinal manipulative therapy; SMT: Spinal
manipulative therapy
Acknowledgements
Not applicable.
Funding
This study was funded by an intra-mural grant from the School of Health
Professions, Murdoch University, Western Australia. The funding body had no
role in the study design, data collection, analysis or interpretation of the data.
Availability of data and materials
The datasets analysed during the current study are available from the
corresponding author on reasonable request.
Authorscontributions
All authors contributed to the design of the study. SD and BL conducted the
data collection. SD performed the statistical analysis with assistance from PD.
SD wrote the first manuscript draft and performed revisions with input from
all authors. All authors agreed to the final manuscript.
Competing interests
Bruce F Walker is Editor in Chief of Chiropractic & Manual Therapies but played
no part in the editorial process of this submission. All other authors declare that
they have no competing interests.
Consent for publication
Consent for publication has been obtained for any relevant images in this
manuscript.
Ethics approval and consent to participate
This study was approved by the Human Research Ethics Committee of Murdoch
University (permit 2014/141). Full informed consent was acquired from all
participants.
Author details
1
Discipline of Chiropractic, School of Health Professions, Murdoch University,
90 South Street, Murdoch, WA 6155, Australia.
2
Discipline of Psychology,
School of Psychology and Exercise Science, Murdoch University, 90 South
Street, Murdoch, WA 6155, Australia.
Received: 5 August 2016 Accepted: 11 October 2016
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... Behavioral studies indicate that SM can decrease pain sensitivity in tissues linked anatomically to the spinal cord segment influenced by SM (Alonso-Perez et al., 2017;Bialosky et al., 2008;Bialosky et al., 2009b;de Camargo et al., 2011;Dorron et al., 2016;Fernandez-Carnero et al., 2008;Fernandez-de-las-Penas et al., 2007;Fryer et al., 2004;George et al., 2006;Laframboise et al., 2016). This suggests that the pain inhibitory effect of SM may rely, at least in part, on segmental mechanisms. ...
... Yet, it suggests that both interventions have comparable effects on segmental pressure pain sensitivity. It remains to be determined how they compare on other effects and mechanisms described below.The effects of SM on PPTs around the SM application site or in a related dermatome have been assessed in several studies(Alonso-Perez et al., 2017;de Camargo et al., 2011;Dorron et al., 2016;Fernandez-Carnero et al., 2008;Fernandez-de-las-Penas et al., 2007;Laframboise et al., 2016). Following a single cervical SM in healthy volunteers, PPTs were increased (i.e. ...
... Similar findings were observed in patients with musculoskeletal pain(Fernandez-Carnero et al., 2008). Regional effects have also been reported for PPTs of myofascial tissues innervated by a spinal segment (myotome) related to the spinal level on which SM was applied(de Camargo et al., 2011;Dorron et al., 2016;Laframboise et al., 2016). ...
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Together, neck pain and back pain are the first cause of disability worldwide, accounting for more than 10% of the total years lived with disability. In this context, chiropractic care provides a safe and effective option for the management of a large proportion of these patients. Chiropractic is a healthcare profession mainly focused on the spine and the treatment of spinal disorders, including spine pain. Basic studies have examined the influence of chiropractic spinal manipulation on a variety of peripheral, spinal, and supraspinal mechanisms involved in spine pain. While spinal cord mechanisms of pain inhibition contribute at least partly to the pain‐relieving effects of chiropractic treatments, the evidence is weaker regarding peripheral and supraspinal mechanisms, which are important components of acute and chronic pain. This narrative review highlights the most relevant mechanisms of pain relief by spinal manipulation and provides a perspective for future research on spinal manipulation and spine pain, including the validation of placebo interventions that control for placebo effects and other non‐specific effects that may be induced by spinal manipulation.
... Regarding pressure pain threshold, there was no significant increase in the pain threshold for either the IG or CG, which is similar to the results reported by Dorron et al. [48], confirming that manipulation would not have an immediate effect. However, Dorron et al. [48] did find significant differences in relation to the baseline when the pressure pain threshold was assessed 10, 20, and 30 min after the manipulation, with the pain threshold increasing up to 12%. ...
... Regarding pressure pain threshold, there was no significant increase in the pain threshold for either the IG or CG, which is similar to the results reported by Dorron et al. [48], confirming that manipulation would not have an immediate effect. However, Dorron et al. [48] did find significant differences in relation to the baseline when the pressure pain threshold was assessed 10, 20, and 30 min after the manipulation, with the pain threshold increasing up to 12%. Additionally, investigating [49] found an increase in the pain threshold immediately after manipulation, as did Millan et al. [50] who confirmed an effect of spinal manipulative therapy on the pressure pain threshold. ...
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Background: According to the American Physical Therapy Association, there is strong evidence to show that vertebral mobilization and manipulation procedures can be used to improve spinal and hip mobility and reduce pain and incapacity in low back pain patients that fit the clinical prediction rule. Objectives: To evaluate the immediate effects of high-velocity low-amplitude (HVLA) manipulation on pain and postural control parameters in individuals with nonspecific low back pain. Methods: This study used a participant-blinded and assessor-blinded randomized controlled clinical trial involving a single session, in which 24 participants were randomly distributed into control (simulated manipulation) and intervention (HVLA lumbar manipulation) groups. The primary (pain: subjective pain intensity and pressure pain threshold) and secondary outcomes (postural control: ellipse area, center of pressure [COP] excursion, COP RMS velocity, and differences between the COP and center of projected gravity) were evaluated before and after the session using a numerical pain scale, algometer, and a force platform. For all outcomes, multiple mixed 2 (group) × 2 (time) ANOVAs were performed. Results: For the subjective pain intensity, only time was significant as a main effect, where pre-intervention presented a greater value then post-intervention (F [1.44] = 4.377; p = 0.042; r = 0.30). For the pressure pain threshold no significant effect was found. For the postural control parameters, as a main effect, only the ellipse area was significantly greater in the control group (F [1.44] = 6.760; p = 0.013; effect size = 0.36). Conclusions: There was a reduction in subjective pain intensity, evaluated using a numerical scale, in both the intervention and control groups immediately after the intervention, suggesting that the spinal manipulation had a similar effect to the placebo procedure. No effect of HVLA lumbar manipulation was identified for postural control variables in either the intervention or control groups. Trial registration: The study was registered at ClinicalTrials.gov under the number NCT02312778, registered at 14 September 2014.
... Além disso, Moehlecke et al. [15], afirma que a técnica manipulativa tem efeito fisiológico rápido, causando alterações química, mecânicas e térmicas, gerando uma resposta-reflexo de analgesia, através do estado de facilitação central da medula espinhal que influencia os neurônios aferentes proprioceptivos. Assim, há uma diminuição na atividade eletromiográfica dos músculos paravertebrais lombares persistente até 30 minutos após a manipulação, no local e circunscrito, mas não sistêmica [13,16]. ...
... De forma geral, os ensaios clínicos sobre MAM, desenvolvem critérios metodológicos onde é realizada a técnica manipulativa em um ponto específico da coluna lombar ou isso é feito de forma inespecífica [13,15,16]. É importante destacar que as lombalgias são provocadas por diferentes fatores, em diferentes pacientes [6,7]. ...
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O objetivo do presente estudo é revisar a literatura sobre a manipulação articular manual (MAM) e seus efeitos em indivíduos com lombalgia. Trata-se de uma revisão de literatura, realizada pela seleção de artigos nas bases de dados Periódico da CAPES, Scielo e PubMed Central, publicados nos últimos 5 anos (2015-2019). A pesquisa foi limitada à língua portuguesa e inglesa, com estudos realizados em humanos, foram excluídos resumos de dissertações ou teses acadêmicas, artigos de revisão e de opinião. Os desfechos considerados foram: efeito da manipulação na dor lombar aguda ou crônica, na qualidade de vida, na amplitude de movimento da coluna (ADM) e na incapacidade. A seleção dos artigos foi inicialmente através da apreciação dos títulos e em seguida dos resumos, que tinham potencial relevância, assim na sequência foi analisado cautelosamente em relação a elegibilidade através da leitura do artigo completo. E esta revisão foi realizada por meio de dois revisores independentes. Diante das buscas foram encontrados 102 artigos, desses, apenas 8 foram incluídos no estudo. Os resultados obtidos nesta revisão descrevem efeitos positivos da técnica MAM em sintomas de lombalgias, como dor, ADM e incapacidade, entretanto seus efeitos em QV permaneceram sem conclusões específicas neste caso.Palavras-chave: dor lombar, manipulação musculoesquelética, manipulação da coluna.
... The patient will be positioned in lateral decubitus with the target side up, knee flexed, and lower hip extended; the physiotherapist will stabilise the shoulder with the cephalic hand and the thigh with his leg and make manual contact with the caudal hand over the process nipple on the upper side of the vertebra to be manipulated with the hypothenar region of the caudal hand. The manipulation will be performed with a passive rotation movement at high speed and low amplitude in the posteroanterior direction in association with the fall of the applicator body [18,32]. The intervention will be carried out in a single moment. ...
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Background Low back pain is one of the main public health concerns. Chronic low back pain (cLBP) reduces functional capacity and affects postural stability. Although health professionals widely use spinal manipulation, its immediate effect on painful sensitivity and postural stability is lacking. This study aims to verify the immediate effects of lumbar spinal manipulation on the pressure pain threshold and postural stability in individuals with cLBP. Methods A two-arm, placebo-controlled clinical trial with parallel groups and examiner-blinded will be conducted with 80 participants with cLBP from an outpatient physical therapy department, randomly allocated at a 1:1 distribution. The experimental group will receive a lumbar spinal manipulation technique, and the placebo group will receive a simulated lumbar spinal manipulation. Both groups will receive one session of treatment and will be evaluated before and immediately after the intervention. The primary outcomes will be the pressure pain threshold and postural stability. Pain intensity and patient’s expectation will be assessed as a secondary outcome. The pressure pain threshold will be assessed using a pressure algometer in 6 different anatomical regions. The evaluation of postural stability will be performed in a baropodometry exam by displacing the centre of pressure. The pain intensity will be measured using the Numeric Pain Rating Scale. A Likert scale will be used for the patient’s expectation about the treatment. A two-way analysis of variance will compare the effect of the interventions between groups. Discussion This study will provide insights regarding the immediate effects of spinal manipulation in patients with cLBP against a simulated spinal manipulation using objective outcomes and considering patients’ expectations regarding the treatment. Trial registration Brazilian Registry of Clinical Trials RBR-3ksq2c . Registered on 13 July 2020
... Peripheral local noxious stimulation makes peptidergic group IV fibres release peptides from their terminals, starting various pathophysiological processes including a reduction in pressure pain thresholds and contributing to a mechanical hyperalgesia (Jayaseelan et al., 2019;Plinsinga et al., 2015;Rio et al., 2014;Scott et al., 2013;Tang et al., 2018;Tompra et al., 2016). Based on this notion, the present study used the lumbar spine manipulation to reduce the nervous system sensitization and provide a possible improvement in ATP (Dorron et al., 2016;Zafereo and Deschenes, 2015). Similar findings with the present study have been reported in patients with lateral epicondylalgia and rotator cuff tendinopathy when cervical and thoracic spine manipulation have been applied respectively, highlighting the pain modulatory effect of this technique (Fernandez-Carnero et al., 2008;Muth et al., 2012;Rompe et al., 2001;Silva et al., 2018). ...
Research
Abstract Background/purpose Cervical and thoracic spine manipulation has been found to reduce tendon pain and disability in lateral epicondylalgia and rotator cuff tendinopathy. Based on these findings, the application of lumbar spine manipulation may also provide similar improvements in Achilles tendinopathy (AT). Therefore, the purpose of this study was to evaluate the effect of lumbar spine manipulation on pain and disability in a patient experiencing AT. Case description A 44 years old male ex-football player presented with a 20-year history of persistent Achilles tendon pain (ATP) consistent with AT diagnosis. The patient attended 12 treatment sessions receiving a high-velocity, low amplitude lumbar spine manipulation. Outcome measures were collected at baseline, 2 weeks, 4 weeks, 3 months and 6 months and included pain in visual analogue scale, the American Orthopedic Foot and Ankle Score, the 36-Item Short Form Health Survey and the Victorian Institute of Sport Assessment-Achilles questionnaire. Pressure pain threshold was also assessed using an electronic pressure algometer. Outcomes Improvement in all outcome measures was noted 6-months post intervention. Outcome measures indicated substantial improvements in both the patient’s pain and disability. The patient was able to perform activities of daily living without difficulties, suggesting higher level of function and quality of life at 6-months post initial evaluation. Conclusion These findings have demonstrated the positive effects of lumbar spine manipulation on ATP and disability. Further studies, specifically clinical trials investigating the effect of lumbar spine manipulation or combining this technique with exercises and functional activities are suggested. Keywords Achilles tendontendinopathymanipulation
... These lumbar SMT studies are in asymptomatic ( Orakifar et al., 2012;Thomson et al., 2009), chronic LBP (de Oliveira et al., 2013;Côté et al., 1994), and exercise-induced LBP populations ( Gay et al., 2014). Only one study, in asymptomatic participants, has observed an increase in PPT after lumbar SMT ( Dorron et al., 2016). This apparent discrepancy suggests there could be a difference in how PPT changes after lumbar SMT compared to cervical or thoracic SMT, which deserves further attention. ...
Article
Background: Changes in quantitative sensory tests have been observed after spinal manipulative therapy (SMT), particularly in pressure pain thresholds (PPT) and temporal summation (TS). However, a recent systematic review comparing SMT to sham found no significant difference in PPT in patients with musculoskeletal pain. The sham-controlled studies were generally low quality, and conclusions about other quantitative sensory tests could not be made. Objectives: We aimed to perform a sham-controlled study with the specific objective of investigating changes in PPT and TS short-term after lumbar SMT compared to sham manipulation in people with low back pain. Methods: This was a double-blind randomised controlled trial comparing high-velocity low-amplitude lumbar SMT against sham manipulation in participants with low back pain. Primary outcome measures were PPT at the calf, lumbar spine and shoulder, and TS at the hands and feet. These were measured at baseline, then immediately, 15 min and 30 min post-intervention. Results: Eighty participants (42 females) were included in the analyses (mean age 37 years), with 40 participants allocated to each intervention group. Significant between-group differences were only observed for calf PPT, which could be explained by a decrease in PPT (increased sensitivity) after SMT and an increase after sham. Feet TS decreased significantly over time after both SMT and sham, and any other changes over time were inconsistent. Conclusions: Our results suggest that lumbar SMT does not have a short-term hypoalgesic effect, as measured with PPT and TS, when compared to sham manipulation in people with low back pain.
... 11 12 The neurophysiological approach suggests that SMT affects the primary afferent neurons from paraspinal tissues, the motor control system, and pain processing. [13][14][15][16][17][18] To resolve the issue of effectiveness, we conducted a systematic review and meta-analysis. This publication is an update of our earlier Cochrane review, which found high quality evidence suggesting no clinically relevant difference between SMT and effective interventions for reducing pain and improving function in patients with chronic low back pain. ...
Article
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Objective To assess the benefits and harms of spinal manipulative therapy (SMT) for the treatment of chronic low back pain. Design Systematic review and meta-analysis of randomised controlled trials. Data sources Medline, PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), CINAHL, Physiotherapy Evidence Database (PEDro), Index to Chiropractic Literature, and trial registries up to 4 May 2018, including reference lists of eligible trials and related reviews. Eligibility criteria for selecting studies Randomised controlled trials examining the effect of spinal manipulation or mobilisation in adults (≥18 years) with chronic low back pain with or without referred pain. Studies that exclusively examined sciatica were excluded, as was grey literature. No restrictions were applied to language or setting. Review methods Two reviewers independently selected studies, extracted data, and assessed risk of bias and quality of the evidence. The effect of SMT was compared with recommended therapies, non-recommended therapies, sham (placebo) SMT, and SMT as an adjuvant therapy. Main outcomes were pain and back specific functional status, examined as mean differences and standardised mean differences (SMD), respectively. Outcomes were examined at 1, 6, and 12 months. Quality of evidence was assessed using GRADE. A random effects model was used and statistical heterogeneity explored. Results 47 randomised controlled trials including a total of 9211 participants were identified, who were on average middle aged (35-60 years). Most trials compared SMT with recommended therapies. Moderate quality evidence suggested that SMT has similar effects to other recommended therapies for short term pain relief (mean difference −3.17, 95% confidence interval −7.85 to 1.51) and a small, clinically better improvement in function (SMD −0.25, 95% confidence interval −0.41 to −0.09). High quality evidence suggested that compared with non-recommended therapies SMT results in small, not clinically better effects for short term pain relief (mean difference −7.48, −11.50 to −3.47) and small to moderate clinically better improvement in function (SMD −0.41, −0.67 to −0.15). In general, these results were similar for the intermediate and long term outcomes as were the effects of SMT as an adjuvant therapy. Evidence for sham SMT was low to very low quality; therefore these effects should be considered uncertain. Statistical heterogeneity could not be explained. About half of the studies examined adverse and serious adverse events, but in most of these it was unclear how and whether these events were registered systematically. Most of the observed adverse events were musculoskeletal related, transient in nature, and of mild to moderate severity. One study with a low risk of selection bias and powered to examine risk (n=183) found no increased risk of an adverse event (relative risk 1.24, 95% confidence interval 0.85 to 1.81) or duration of the event (1.13, 0.59 to 2.18) compared with sham SMT. In one study, the Data Safety Monitoring Board judged one serious adverse event to be possibly related to SMT. Conclusion SMT produces similar effects to recommended therapies for chronic low back pain, whereas SMT seems to be better than non-recommended interventions for improvement in function in the short term. Clinicians should inform their patients of the potential risks of adverse events associated with SMT.
... Consequently, the regional PPT testing location reached the 15% change in threshold established as clinically relevant for patient populations, while the local PPT testing location approached the defined threshold [49]. Dorron et al. hypothesized that the immediate analgesia following SMT may further influence clinical outcomes by providing an opportunity to facilitate rehabilitative exercise in patient populations with spinal pain [69]. However, at 3 weeks postintervention, both the SMT and sham SMT groups failed to achieve at least a 15% increase in PPT at the remote location, while the sham SMT group did not meet the established clinical threshold at the local (12.5%) ...
Article
Objectives: The long-term goal of our study is to improve the understanding of the biological mechanisms associated with spinal manipulative therapy (SMT) in low back pain. Methods: This project involved a pilot randomized, blinded clinical trial (ClinicalTrials.gov registration number NCT03078114) of 3-week SMT in chronic nonspecific low back pain (CNSLBP) patients. We recruited 29 participants and randomly assigned them into either a SMT (n = 14) or sham SMT (n = 15) group. Pre- and postintervention, we quantified the effect of SMT on clinical outcomes (Numeric Pain Rating Scale and Oswestry Disability Index) and pressure pain threshold (PPT) at local (lumbar spine), regional (lower extremity), and remote (upper extremity) anatomical sites. Results: We observed a significant main effect for time signifying reduced hypersensitivity (increased PPT) at local (p = .015) and regional (p = .014) locations at 3 weeks. Furthermore, we found significant main effects of time indicating improvements in pain (p < .001) and disability (p = .02) from baseline among all participants regardless of intervention. However, no between-group differences were observed in PPT, clinical pain, or disability between the SMT and sham SMT groups over 3 weeks. Conclusions: After 3 weeks of SMT or sham SMT in CNSLBP patients, we found hypoalgesia at local and remote sites along with improved pain and low back-related disability. Level of Evidence: 1b
... The mechanism by which SM modulates pain remains poorly defined; however, there is evidence to suggest that analgesia may occur after SM [13,14]. There are a variety of observed and proposed phenomena that may explain the mechanisms for the psychological, mechanical, or neurophysiological responses from a SM associated with alterations in pain processing or sympathetic and motor systems' excitation [15,16]. ...
Article
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Study Design: Randomized clinical trial with pre-test, post-test control group design. Objectives: To examine the immediate effects of cervical spinal manipulation (CSM) on serum concentration of biochemical markers (oxytocin, neurotensin, orexin A, and cortisol). Background: Several studies have found an association between spinal manipulation (SM) and pain perception. However, the mechanism by which SM modulates pain remains undefined. Methods: Twenty-eight female subjects with non-specific mechanical neck pain were randomly assigned to one of two interventions (CSM versus sham CSM). Blood samples were drawn before and immediately after the respective interventions. Oxytocin, neurotensin, orexin A, and cortisol were measured from the blood and serum using the Milliplex Map Magnetic Bead Panel Immunoassay on the Luminex 200 Platform. Results: In the CSM group, there were significant increases in pre- versus post-manipulation mean oxytocin (154.5 ± 60.1 vs. 185.1 ± 75.6, p = .012); neurotensin (116.0 ± 26.5 vs.136.4 ± 34.1, p < . 001); orexin A (52.2 ± 31.1 vs. 73.8 ± 38.8, p < .01) serum concentration; but no significant differences in mean cortisol (p = .052) serum concentration. In the sham group, there were no significant differences in any of the biomarkers (p > .05). Conclusion: The results of the current study suggest that the mechanical stimuli provided through a CSM may modify neuropeptide expression by immediately increasing the serum concentration of nociception-related biomarkers (oxytocin, neurotensin, orexin A, but not cortisol) in the blood of female subjects with non-specific mechanical neck pain.
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Background: Low back pain is one of the main public health concerns. Chronic low back pain (cLBP)reduces functional capacity and affects postural stability.Although health professionals widely use spinal manipulation, its immediate effect on painful sensitivity and postural stability is lacking. This study aims to verify the immediate effects of lumbar spinal manipulation on the pressure pain threshold and postural stability in individuals with cLBP. Methods: A two-arm, placebo-controlled clinical trial with parallel groups and examiner-blinded will be conducted with 80 participants with cLBPfrom an outpatient physical therapy department,randomly allocated at a 1:1 distribution. The experimental group will receive a lumbar spinal manipulation technique, and the placebo group will receive a simulated lumbar spinal manipulation. Both groups will receive one session of treatment and will be evaluated before and immediately after the intervention.The primary outcomes will be the pressure pain threshold and postural stability. Pain intensity and patient´s expectation will be assessed as a secondary outcome. The pressure pain threshold will be assessed using a pressure algometer in 6 different anatomical regions. The evaluation of postural stability will be performed in a baropodometry exam by displacing the centre of pressure. The pain intensity will be measuredusing the Numeric Pain Rating Scale. A Likert scale will be used for the patient´s expectationabout the treatment. A two-way analysis of variance will compare the effect of the interventions between groups. Discussion:This study will provide insights regarding the immediate effects of spinal manipulation in patients with cLBPagainst a simulated spinal manipulation using objective outcomes and considering patients’ expectations regarding the treatment. Trial registration: Brazilian Registry of Clinical Trials:RBR-3ksq2c; registered on 13 July 2020.
Article
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Introduction Experimental pain studies can provide unique insight into the dimensions of pain and into individual differences in pain responsiveness by controlling different aspects of pain-eliciting stimuli and pain measures. In experimental pain studies, pain responsiveness can be assessed as pain threshold, pain tolerance or pain ratings. The test-theoretical qualities of these different measures, however, have not yet been completely documented. In the current study, several of these qualities were investigated in a pain experiment applying different algometric techniques. The objective of the study was to investigate the reliability (test–retest) and the convergent validity (correspondence) of the different methods found in the literature of measuring pressure-pain threshold, and the interrelationship between pressure-pain threshold, pressure-pain tolerance, and pressure-pain ratings. Methods Sixty-six healthy female subjects were enrolled in the study. All pressure stimuli were applied by a trained investigator, using a digital algometer with a 1 cm ² rubber tip. Pressure-pain thresholds were assessed repeatedly on six different body points (i.e. left and right calf one third of total calf muscle length below the popliteal space), the lower back (5 cm left and right from the L3), and left and right forearm (thickest part of brachioradialis muscle). Next, pressure-pain tolerance was measured on the thumbnail of the non-dominant hand, followed by rating affective and sensory components (on visual analogue scales) of a stimulus at tolerance level. Last, affective and sensory ratings were obtained for two pressure intensities. Results With intraclass correlations above .75 for pain responses per body point, test–retest reliability was found to be good. However, values obtained from all first measurements were significantly higher as compared with the two succeeding ones. Convergent validity of pain thresholds across different body points was found to be high for all combinations assessed (Cronbach’s alpha values >.80), but the highest for bilateral similar body parts (>.89). Finally, principal components analysis including measures of threshold, tolerance and pain ratings yielded a three-factor solution that explained 81.9% of the variance: Moderate-level stimulus appraisal & pain tolerance; Pain threshold; Tolerance-level stimulus appraisal . Conclusion and implications Findings of the current study were used to formulate recommendations for future algometric pain studies. Concerning pressure-pain threshold, it is recommended to exclude first measurements for every body point from further analyses, as these measurements were found to be consistently higher compared with the following measurements. Further, no more than two consecutive measurements (after the first measurement) are needed for a reliable mean threshold value per body point. When combining threshold values of several body points into one mean-aggregated threshold value, we suggest to combine bilateral similar points, as convergent validity values were highest for these combinations. The three-factor solution that was found with principal components analyses indicates that pressure-pain threshold, subjective ratings of moderate intensity stimuli, and subjective ratings of the maximum (tolerance) intensity are distinct aspects of pain responsiveness. It is therefore recommended to include a measure of each of these three dimensions of pain when assessing pressure pain responsiveness. Some limitations of our study are discussed.
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BACKGROUND: Three different types of manual therapy techniques for patients with neck pain and relationship with psychological factors has not been evaluated. AIM: To compare the effectiveness high velocity and low amplitude (HVLA) manipulation vs. posteroanterior mobilization (PA mob) vs. sustain appophyseal natural glide (SNAG) in the management of patients with neck pain and to evaluate the interaction with psychological factors. STUDY DESING: Randomized clinical trial. SETTING: Primary Health Care Center. POPULATION: Patients with history of chronic neck pain over the last 3 months were recruited. METHODS: Patients were randomly assigned to receive treatment with HVLA (N.=15), with PA mob (N.=16) or with SNAG (N.=17). One session was applied. Pain intensity of neck pain, pressure pain threshold over processus spinosus of C2 (PPT_C2) and cervical range of motion (CROM) were measured pre- and post-intervention. Pain catastrophizing, depression, anxiety and kinesiophobia were assessed in baseline. ANOVAs were performed, with main effects, two-way (treatment x time) and three-way interactions (treatment x psychological variable x time) were examined. RESULTS: Fourthy-eight patients (mean±SD age, 36.5±8.7 years; 87.5% female). A significant interaction treatment x time was observed for VAS-rest in HVLA and AP mob groups (P<0.05). With more pain relief to HVLA and AP mob groups than SNAG groups but all groups improve the same in CROM. Also, a significant three-way treatment x anxiety x time interaction for VAS in Flexion/Extension was identified (P<0.01), and a trend toward significance was observed for the three way treatment x anxiety x time interaction, with respect to CROM in Lateral-Flexion movement (P<0.05). CONCLUSION: The results suggest that an HVLA and PA mob groups relieved pain at rest more than SNAG in patients with Neck pain. Among psychological factors, only trait anxiety seems interact with Manual therapy, mainly high anxiety conditions interact with the Mobilization and SNAG effects but under low anxiety conditions interact with the HVLA effects. Significant mean differences can be observed both in VAS in Flexion/Extension and in CROM in lateral-flexion movement when using mobilization under high anxiety conditions CLINICAL REHABILITATION IMPACT: The findings provide preliminary evidence to support that three different techniques have similar immediate effects over neck pain and while under high anxiety levels a better outcome is expected after mobilization intervention, under low anxiety levels a better prognosis is expected after manipulation and SNAG intervention.
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Objective The purposes of this study were to use functional magnetic resonance imaging to investigate the immediate changes in functional connectivity (FC) between brain regions that process and modulate the pain experience after 3 different types of manual therapies (MT) and to identify reductions in experimentally induced myalgia and changes in local and remote pressure pain sensitivity. Methods Twenty-four participants (17 men; mean age ± SD, 21.6 ± 4.2 years) who completed an exercise-injury protocol to induce low back pain were randomized into 3 groups: chiropractic spinal manipulation (n = 6), spinal mobilization (n = 8), or therapeutic touch (n = 10). The primary outcome was the immediate change in FC as measured on functional magnetic resonance imaging between the following brain regions: somatosensory cortex, secondary somatosensory cortex, thalamus, anterior and posterior cingulate cortices, anterior and poster insula, and periaqueductal gray. Secondary outcomes were immediate changes in pain intensity, measured with a 101-point numeric rating scale, and pain sensitivity, measured with a handheld dynamometer. Repeated-measures analysis of variance models and correlation analyses were conducted to examine treatment effects and the relationship between within-person changes across outcome measures. Results Changes in FC were found between several brain regions that were common to all 3 MT interventions. Treatment-dependent changes in FC were also observed between several brain regions. Improvement was seen in pain intensity after all interventions (P < .05) with no difference between groups (P > .05). There were no observed changes in pain sensitivity, or an association between primary and secondary outcome measures. Conclusion These results suggest that MTs (chiropractic spinal manipulation, spinal mobilization, and therapeutic touch) have an immediate effect on the FC between brain regions involved in processing and modulating the pain experience. This suggests that neurophysiologic changes after MT may be an underlying mechanism of pain relief.
Article
The purposes of this study were to determine whether there were differences in mean values or reliability for 2 frequently used protocols for pressure pain threshold (PPT) and to calculate how large a difference in PPT is necessary to be 95% confident that a real change has occurred. Thirteen participants (8 females) aged 22.3 (±2.3) years from a university community were included. Two testers evaluated participants using 2 protocols, in which PPT was measured 3 times at 8 different body locations. The "cluster protocol" consisted of 3 successive measurements at each location with a 30-second rest between each measurement. The "circuit protocol" consisted of 1 measurement taken at each anatomical location until "the circuit" was complete and then repeated a total of 3 times. A 2-way analysis of variance did not reveal significant differences between protocols at any body location (P = .46-.98). Intertester reliability was good to excellent for all locations (intraclass correlation coefficient, 0.84-0.96), and limits of agreement ranged from 108 to 223 kPa. Either the cluster or circuit protocol can be used to measure PPT in clinical or research setting. A difference of 160 kPa is considered sufficient to indicate a real difference between repeated measures of PPT regardless of protocol used for testing. Copyright © 2015 National University of Health Sciences. Published by Elsevier Inc. All rights reserved.
Article
Study design: Single-blind randomized trial. Objectives: To compare the effects of cervical and shoulder thrust manipulation (TM) and exercise on pain sensitivity, and to explore associations with clinical outcomes in patients with shoulder pain. Background: Experimental studies indicate that spinal TM has an influence on central pain processes, supporting its application for treatment of extremity conditions. Direct comparison of spinal and peripheral TM on pain sensitivity has not been widely examined. Methods: Seventy-eight participants with shoulder pain (36 female; mean ± SD age, 39.0 ± 14.5 years) were randomized to receive 3 treatments of cervical TM (n = 26), shoulder TM (n = 27), or shoulder exercise (n = 25) over 2 weeks. Twenty-five healthy participants (13 female; mean ± SD age, 35.2 ± 11.1 years) were assessed to compare pain sensitivity with that in clinical participants at baseline. Primary outcomes were changes in local (eg, shoulder) and remote (eg, tibialis anterior) pressure pain threshold and heat pain threshold occurring over 2 weeks. Secondary outcomes were shoulder pain intensity and patient-rated function at 4, 8, and 12 weeks. Analysis-of-variance models and partial-correlation analyses were conducted to examine comparative effects and the relationship between measures. Results: At baseline, clinical participants demonstrated lower local (mean difference, - 1.63 kg; 95% confidence interval [CI]: -2.40, -0.86) and remote pressure pain threshold (mean difference, -1.96 kg; 95% CI: -3.09, -0.82) and heat pain threshold (mean difference, -1.15°C; 95% CI: -2.06, -0.24) compared to controls, suggesting enhanced pain sensitivity. Following intervention, there were no between-group differences in pain sensitivity or clinical outcome (P>.05). However, improvements were noted, regardless of intervention, for pressure pain threshold (range of mean differences, 0.22-0.32 kg; 95% CI: 0.03, 0.43), heat pain threshold (range of mean differences, 0.30-0.58; 95% CI: 0.06, 0.96), pain intensity (range of mean differences, -1.79 to -1.45; 95% CI: -2.34, -0.94), and function (range of mean differences, 3.15-3.82; 95% CI: 0.69, 6.20) at all time points. We did not find an association between pain sensitivity changes and clinical outcome (P>.05). Conclusion Clinical participants showed enhanced pain sensitivity, but did not respond differently to cervical or peripheral TM. In fact, in this sample, cervical TM, shoulder TM, and shoulder exercise had similar pain sensitivity and clinical effects. The lack of association between pain sensitivity and clinical pain and function outcomes suggests different (eg, nonspecific) pain pathways for clinical benefit following TM or exercise. Level of evidence: Therapy, level 1b.
Article
Study design: Randomized controlled trial with follow-up to 6 months. Objective: This was a comparative effectiveness trial of manual-thrust manipulation (MTM) versus mechanical-assisted manipulation (MAM); and manipulation versus usual medical care (UMC). Summary of background data: Low back pain (LBP) is one of the most common conditions seen in primary care and physical medicine practice. MTM is a common treatment for LBP. Claims that MAM is an effective alternative to MTM have yet to be substantiated. There is also question about the effectiveness of manipulation in acute and subacute LBP compared with UMC. Methods: A total of 107 adults with onset of LBP within the past 12 weeks were randomized to 1 of 3 treatment groups: MTM, MAM, or UMC. Outcome measures included the Oswestry LBP Disability Index (0-100 scale) and numeric pain rating (0-10 scale). Participants in the manipulation groups were treated twice weekly during 4 weeks; subjects in UMC were seen for 3 visits during this time. Outcome measures were captured at baseline, 4 weeks, 3 months, and 6 months. Results: Linear regression showed a statistically significant advantage of MTM at 4 weeks compared with MAM (disability = -8.1, P = 0.009; pain = -1.4, P = 0.002) and UMC (disability = -6.5, P = 0.032; pain = -1.7, P < 0.001). Responder analysis, defined as 30% and 50% reductions in Oswestry LBP Disability Index scores revealed a significantly greater proportion of responders at 4 weeks in MTM (76%; 50%) compared with MAM (50%; 16%) and UMC (48%; 39%). Similar between-group results were found for pain: MTM (94%; 76%); MAM (69%; 47%); and UMC (56%; 41%). No statistically significant group differences were found between MAM and UMC, and for any comparison at 3 or 6 months. Conclusion: MTM provides greater short-term reductions in self-reported disability and pain scores compared with UMC or MAM. Level of evidence: 2.
Article
Objective: The purpose of this study was to compare the effects of thoracic thrust manipulation vs thoracic non-thrust mobilization in patients with bilateral chronic mechanical neck pain on pressure pain sensitivity and neck pain intensity. Methods: Fifty-two patients (58% were female) were randomly assigned to a thoracic spine thrust manipulation group or of thoracic non-thrust mobilization group. Pressure pain thresholds (PPTs) over C5-C6 zygapophyseal joint, second metacarpal, and tibialis anterior muscle and neck pain intensity (11-point Numerical Pain Rate Scale) were collected at baseline and 10 minutes after the intervention by an assessor blinded to group allocation. Mixed-model analyses of variance (ANOVAs) were used to examine the effects of the treatment on each outcome. The primary analysis was the group * time interaction. Results: No significant interactions were found with the mixed-model ANOVAs for any PPT (C5-C6: P>.252; second metacarpal: P>.452; tibialis anterior: P>.273): both groups exhibited similar increases in PPT (all, P<.01), but within-group and between-group effect sizes were small (standardized mean score difference [SMD]<0.22). The ANOVA found that patients receiving thoracic spine thrust manipulation experienced a greater decrease in neck pain (between-group mean difference: 1.4; 95% confidence interval, 0.8-2.1) than did those receiving thoracic spine non-thrust mobilization (P<.001). Within-group effect sizes were large for both groups (SMD>2.1), and between-group effect size was also large (SMD = 1.3) in favor of the manipulative group. Conclusions: The results of this randomized clinical trial suggest that thoracic thrust manipulation and non-thrust mobilization induce similar changes in widespread PPT in individuals with mechanical neck pain; however, the changes were clinically small. We also found that thoracic thrust manipulation was more effective than thoracic non-thrust mobilization for decreasing intensity of neck pain for patients with bilateral chronic mechanical neck pain.
Article
Spinal Manipulation (SM) has been purported to decrease pain and improve function in subjects with non-specific neck pain. Previous research has investigated which individuals with non-specific neck pain will be more likely to benefit from SM. It has not yet been proven whether or not the effectiveness of thoracic SM depends on the specific technique being used. This double-blind randomized trial has compared the short-term effects of two thoracic SM maneuvers in subjects with chronic non-specific neck pain. Sixty participants were distributed randomly into two groups. One group received the Dog technique (n=30), with the subject in supine position, and the other group underwent the Toggle-Recoil technique (n=30), with the participant lying prone, T4 being the targeted area in both cases. Evaluations were made of self-reported neck pain (Visual Analogue Scale); neck mobility (Cervical Range of Motion); and pressure pain threshold at the cervical and thoracic levels (C4 and T4 spinous process) and over the site described for location of tense bands of the upper trapezius muscle. Measurements were taken before intervention, immediately afterwards, and twenty minutes later. Both maneuvers improved neck mobility and mechanosensitivity and reduced pain in the short-term. No major or clinical differences were found between the groups. In the between-groups comparison slightly better results were observed in the Toggle-Recoil group only for cervical extension (p = 0.009), right lateral flexion (p = 0.004) and left rotation (p < 0.05).
Article
Previous studies have analyzed the effects of spinal manipulation on pain sensitivity by using several sensory modalities, but to our knowledge, no studies have focused on serum biomarkers involved in the nociceptive pathway after spinal manipulation. Our objectives were to determine the immediate effect of cervical and dorsal manipulation over the production of nitric oxide and substance P, and establishing their relationship with changes in pressure pain thresholds in asymptomatic subjects. In this single-blind randomized controlled trial, 30 asymptomatic subjects (16 men) were randomly distributed into 3 groups (n=10 per group): control, cervical and dorsal manipulation groups. Blood samples were extracted to obtain serum. ELISA assay for substance P and chemiluminiscence analysis for nitric oxide determination were performed. Pressure pain thresholds were measured with a pressure algometer at the C5-C6 joint, the lateral epicondyle and the tibialis anterior muscle. Outcome measures were obtained before intervention, just after intervention and 2 hours after intervention. Our results indicated an increase in substance P plasma level in the cervical manipulation group (70.55 %) when compared with other groups (P<0.05). This group also showed an elevation in the pressure pain threshold at C5-C6 (26.75 %) and lateral epicondyle level (21.63 %) immediately after the intervention (P<0.05). No changes in nitric oxide production were observed. In conclusion, mechanical stimulus provided by cervical manipulation increases substance P levels and pressure pain threshold but does not change nitric oxide concentrations. Part of the hypoalgesic effect of spinal manipulation may be due to the action of substance P.