FDBAdmin Forschungsdatenbank der Universit t Z rich Medizinische abdominal muscle

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					Forschungsdatenbank der Universität Zürich
Medizinische Fakultät > Rheumaklinik und Institut für physikalische Medizin >
PD Dr. Anne Mannion


Development of a clinical prediction rule to identify patients with chronic low back pain who
respond positively to spine stabilisation exercises.

Summary / Zusammenfassung
Summary of results
Background
Exercise therapy is one of the few evidence-based treatments for non-specific cLBP, although it
does not elicit a positive response in all patients. The reasons for the widely varying individual
responses are not known, although many believe that it is the result of an inappropriate, “one-
sizefits-all” approach to treatment; it is argued that, instead, specific types of exercise should be
prescribed for specific patients, determined on the basis of their individual LBP history, signs,
symptoms, and functional disturbances. Nonetheless, identifying “the right treatment for the right
patient” is far from easy.
Dysfunction in the activation of the deep-lying trunk muscles, measured using intramuscular
electromyography (EMG), is one disturbance that has been observed in connection with LBP; it is
believed to pose a threat to segmental stability and hence predispose to continuing/future episodes
of pain. As such, "spine stabilisation exercises", aimed at restoring deep trunk muscle motor
control, have become a popular concept in physiotherapy. However, there are still many
“unknowns” in relation to both the extent and nature of the proposed dysfunction and the
mechanism of action of the specific exercise treatment. Since intramuscular EMG is invasive, a
prerequisite for the in depth investigation of these phenomena is the availability of a reliable,
accurate and sensitive means for assessing deep trunk muscle function. The objectives of our study
were to develop such a method, based on M-mode ultrasound and tissue velocity information from
tissue Doppler imaging (TDI), and use it to examine the trunk muscle function of patients with
cLBP compared with healthy controls and compared with themselves after a physiotherapy
programme of spine stabilisation exercises.
Methods
Development and validity of the non-invasive ultrasound method.
Fourteen healthy subjects made rapid arm movements, in standing, in response to a visual signal
indicating the required movement direction. Recordings were made of medial deltoid (MD)
surface EMG, and of fine-wire intramuscular EMG and TDI tissue-velocity changes of the
contralateral transversus abdominis (TrA), obliquus internus (OI) and obliquus externus (OE)
(=the lateral abdominal muscles). Muscle onsets of activity were determined by blinded visual
analysis of EMG and TDI data. TDI could not distinguish between the relative activation of the
three muscles, so in subsequent analyses only the onset of the earliest abdominal muscle activity
was used. The latter occurred <50ms after the onset of medial deltoid EMG (i.e. was feedforward)
and correlated significantly with the corresponding EMG-onsets (r=0.47, p<0.0001). The mean
difference between methods was 20ms, and was likely explained by electromechanical delay;
limits of agreement were wide (-40 to +80ms) but no greater than those typical of repeated
measurements using either technique. TDI yielded reliable and valid measures of the earliest onset
of feedforward activity within the lateral abdominal muscle group.
Main results
Evaluation of lateral abdominal muscle function in cLBP .
In 50 patients with cLBP and 50 matched, pain-free controls, the ability to preferentially activate
and increase the thickness of the TrA during an “abdominal hollowing” exercise was examined
using M-mode ultrasound; the feedforward activity of the lateral abdominal muscle group during

Project 11506                                                                                  Seite 1
rapid arm movements was also assessed, using the new TDI technique. Patients self-rated their
pain and disability in everyday activities.
In both groups, feed-forward activity of the lateral abdominal muscles (<50 ms after MD
activation) was recorded during arm movements in all directions. There was a tendency for the
onset of the earliest abdominal muscle activity to be slightly earlier in the cLBP group than in the
control group, reaching significance for left arm movements (p=0.015). There was no significant
relationship between the muscle onsets (mean over all directions and sides) and pain or self-rated
disability. The mean TrA contraction ratio (i.e., thickness of the muscle during contraction divided
by the thickness at rest) during abdominal hollowing was significantly lower in the cLBP patients
than in the controls (p=0.02), although the difference was not great (1.35 ± 0.14 vs 1.44 ± 0.23
respectively). The TrA contraction ratio showed a low but significant negative correlation with
selfrated disability (Roland Morris (RM) score) (r=-0.40, p=0.004), i.e., higher disability was
associated with a lesser ability to activate the TrA.
Effect of a programme of spine stabilization exercises on lateral abdominal muscle function, pain
and disability in patients with cLBP.
32/37 (86%) patients completed a 9-week physiotherapy programme of spine stabilization
exercises (PT-SS). The RM disability score showed a moderate, significant decrease after
treatment (from 8.9 ± 4.7 to 6.7 ± 4.3), as did average pain intensity (from 4.7 ± 1.7 to 3.5 ± 2.3)
(each p<0.01). The mean TrA contraction ratio increased significantly from 1.34 ± 0.12 to 1.41 ±
0.17 (p=0.04) and improvements were seen in various functional tests simulating everyday
activities (p<0.05). However, on an individual level no functional changes bore a significant
relationship to the corresponding changes in pain or disability. There was no significant response
to therapy in the onset of the earliest lateral abdominal muscle activity during rapid arm
movements (p=0.53).
Implications and practice
In contrast to popular belief in physiotherapy practice, the voluntary activation of the TrA has only
a minor role, and the anticipatory (feedforward) activity of the lateral abdominal muscles appears
to have no role in cLBP, as far as distinguishing between patients and controls, correlating with
self-rated pain and disability, responding to specific exercise therapy, and explaining treatment
effects are concerned.
There is evidence from RCTs for the effectiveness of spine stabiliation exercises as a treatment for
cLBP (regardless of their mechanism of action), and our studies hence provide no grounds to

Publications / Publikationen
1) Mannion AF, Pulkovski N, Gubler D, Gorelick M, O'Riordan D, Loupas T, Schenk P, Gerber
H, Sprott H (2008) Muscle thickness changes during abdominal hollowing: an assessment of
between-day measurement error in controls and patients with chronic low back pain. Eur Spine J.
17(4):494-501.
2) Mannion AF, Pulkovski N, Schenk P, Hodges PW, Gerber H, Loupas T, Gorelick M, Sprott H
(2008) A new method for the non-invasive determination of abdominal muscle feedforward
activity based on tissue velocity information from tissue Doppler imaging. J Appl Physiol. 104
(4):1192-201
3) Pulkovski N, Schenk P, Maffiuletti N, Mannion AF (2008) Tissue Doppler imaging for
detecting onset of muscle activity. Muscle Nerve. 37(5):638-49
4) Mannion AF, Pulkovski N, Toma V, Sprott H (2008) Abdominal muscle size and symmetry at
rest and during abdominal hollowing exercises in healthy control subjects. J Anat. 213 (2): 173
-182
5) Mannion AF, Pulkovski N, Helbling D, Sprott H (2008) The influence of adherence with


Project 11506                                                                                 Seite 2
therapy on clinical outcome after a spine stabilisation exercise program in patients with chronic
non-specific low back pain. International Society for the Study of the Lumbar Spine (Spine Week),
Geneva, Switzerland, 26.5.08-31.5.08
6) Mannion AF, Pulkovski N, Schenk P, Hodges PW, Gerber H, Gorelick M, Sprott H (2008)
“Direction-dependent” feed-forward activation of transversus abdominis during rapid arm
movements challenges its unique role in spine stabilisation. International Society for the Study of
the Lumbar Spine (Spine Week), Geneva, Switzerland, 26.5.08-31.5.08
7) Sprott H, Pulkovski N, Toma V, Mannion AF. (2008) Abdominal muscle size and symmetry at
rest and during abdominal hollowing exercises in healthy control subjects. International
Association for the Study of Pain, 12th World Congress on Pain, Glasgow, UK, 17-22.8.2008.
8) Mannion AF, Helbling D, Pulkovski N, Sprott H (2009) Spinal segmental stabilisation exercises
for chronic low back pain: programme adherence and its influence on clinical outcome.Eur Spine
J. 18(12):1881-91
9) Meyer K, Tschopp A, Sprott H, Mannion AF (2009) The association between catastrophizing
and self-rated pain and disability in patients with chronic low back pain. J Rehab Med 41(8):620-5

Project Leadership and Contacts / Projektleitung und Kontakte
PD Anne F Mannion, PhD (Project Leader)                                      anne.mannion@kws.ch

Funding Source(s) / Unterstützt durch
SNF (Programm NFP)
NFP53, grant for implementation of findings of study 405340-104787


Duration of Project / Projektdauer
Dec 2008 to Jan 2009




Project 11506                                                                                Seite 3

				
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