A chronic pain in the back Previous attempts to subgroup patients with CNSLBP utilised diagnostic imaging
Low back pain (LBP) afflicts most people at some point in their lives but trying to but numerous studies and reviews have shown that abnormalities once thought
Diagnostic
measure the prevalence of LBP is not straightforward. Prevalence and LBP have to cause pain, including spondylolisthesis, disc degeneration and osteophytes,
various interpretations and issues arise from varying methodologies between are not exclusive to symptomatic populations
15-18
. Even provocation discography
imaging
studies
1
. Consequently, the prevalence of LBP is quoted as a range. For instance, a is contentious as high false positive rates in asymptomatic participants have been
systematic review
2
between 1966 and 1998 determined the lifetime prevalence of reported
19
, though a recent systematic review concluded these were not as high as
increases
low back pain in English speaking countries to be between 11-81 per cent, whilst previously thought
20
.
Waddell
3
reported it to be between 59-84 per cent. However, of more interest, is
patient
that these ranges have not increased over time
4
, although the increase in disability In response to such findings, The Royal College of Radiologists recommends
and the burden placed on social and health care systems rose so much in the that radiographs are not performed for CNSLBP
21
. Additionally, in May 2009, the
satisfaction with
decades from 1985
5
that one eminent spinal surgeon
3
labelled LBP ‘a 20th century National Institute for Health and Clinical Excellence (NICE) will publish guidelines
medical disaster’. for the management of CNSLBP recommending that MRI is not undertaken
treatment
within the first 12 months
22
. There is evidence that the use of diagnostic imaging
For the majority of sufferers, LBP will ease with time and without any intervention increases patient satisfaction with treatment
23
but this does not necessarily relate
other than simple pain killers. Nachemson et al
6
noted that only 10 per cent suffer to improved outcomes and, in fact, is more likely to lead to more invasive (and
disabling back pain after six weeks, later supported by results from Coste et al
7
. expensive) interventions
24
, putting further pressure on health and social care.
However, more recent studies calculated the recovery rate to be only 76 per cent
at three months
8
with one-third of people still not recovered a year later
9
. Of those Common sense suggests that if mechanical back pain is influenced by movement,
who go on to develop chronic low back pain (CLBP), only 15 per cent will have any then measuring movement may help determine the nature of the problem. In
kind of specific or serious pathology and few will have nerve root problems. For vitro studies of spinal motion in healthy, degenerate, and diseased spines are well
the remainder, no cause will be found
3
. CLBP is defined as pain lasting for more established
25-28
and from such studies it is known that the healthy intact spine is a
than 12 weeks
10
although this fails to take into account recurring, or episodic, LBP relatively stable structure in the neutral position. It can withstand substantial forces
which can also be chronic. Von Korff suggested the term ‘chronic’ should also apply and moves in a uniform and predictable way when force is increased. Conversely,
if pain has been present on more than half of the days of the previous year
11
. a spine with damaged or diseased inter-vertebral discs does not have resistance
Hence there is also ambiguity over the definition of ‘chronic’ in relation to low to force and will move quickly and rapidly to its maximum range of motion. The
back pain
12
. explanation for such laxity is known as the neutral zone (NZ) theory
29
.
In the absence of a specific cause, chronic non specific low back pain Neutral zone theory is of particular interest as an alternate method for describing,
(CNSLBP) is often assumed to be mechanical in nature
10
, ie affected by and so diagnosing, ‘instability’ of the spine, although confusion exists because
movement and originating from the holding structures of the spine such as the term ‘instability’ has different meanings for different specialists (clinicians,
the ligaments, muscles and inter-vertebral discs. However, as is the case with radiologists, bio-engineers)
30,31
. Previous attempts to provide a biomechanical
‘prevalence’ and ‘chronic’ there is still no universal definition for mechanical definition of instability include hyper-mobility of rotation and increased sagittal
low back pain
13,14
, so the benefits of ‘mechanical’ treatments aimed at this plane translation with values of 10 degrees and 4mm being used respectively
32,33
.
group, such as spinal manipulation, mobilisation and surgical fusion, are However, these values fail to describe adequately the mechanical properties of the
difficult to predict. spine due to difficulties in determining the cut off between normal and abnormal
31
.
There is substantial overlap between symptomatic and asymptomatic range of
The problem seems to be the heterogeneity of patients with CNSLBP. The varying motion
32
and sagittal rotation may be as high as 25 degrees in healthy young
definitions and meanings of relevant terms mean that comparison across studies volunteers
34
. Measuring the NZ and the quality of motion may be a better way
and pooling of data is complicated and subject to high errors. Additionally, CNSLBP forward in determining which patients with CNSLBP need further or more invasive
is a symptom, but selecting the appropriate treatment is difficult when the cause mechanical interventions. But, because the NZ has been difficult to identify in vivo,
is not known. Consequently, there is a need to further sub-categorise patients with the link between motion features and CNSLBP is yet to be proven.
CNSLBP to enable more focused clinical trials into causes and treatment, and to
reduce the pressure on social and health care. In vivo measurements of spinal motion include goniometry which uses data
2009
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IMAGING & ONCOLOGY
|
35
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