British Journal of Rheumatology 1996;35:1269-1273
THE VALUE OF SPECT SCANS IN IDENTIFYING BACK PAIN LIKELY
TO BENEFIT FROM FACET JOINT INJECTION
A. L. DOLAN, P. J. RYAN, N. K. ARDEN, R. STRATTON, J. R. WEDLEY,* W. HAMANN,*
I. FOGELMANt and T. GIBSON
Clinical Rheumatology Unit, *Pain Relief Unit and ^Nuclear Medicine Department, Guy's Hospital, London
SUMMARY
Lumbar facet disease is sometimes implicated in low back pain. Identification is difficult and this may account for a variable
response. Single photon emission computerized tomography (SPECT) is a scanning technique which enables localization of facet
joint pathology. We determined whether recognition of facet disease by this method improved the response to corticosteroid
injection treatment. Fifty-eight patients with low back pain and displaying accepted clinical criteria for facet joint disease were
evaluated by SPECT. Twenty-two had facetal uptake of isotope. These and the tender facet joints of 36 scan-negative patients
were injected with 40 mg methylprednisolone and 1 ml 1% lignocaine under X-ray control. Pain was assessed by a blind observer
using the McGill questionnaire (MGQ), Present Pain Intensity score (PPI) and a Visual Analogue Scale (VAS). VAS, PPI and
MGQ were reduced in the scan-positive patients at 1 month (P = 0.05, P = 0.0005, P = 0.005) and MGQ at 3 months (P = 0.01),
whilst scan-negative patients were unchanged. The percentage of scan-positive patients who reported improvement was 95%
at 1 month and 79% at 3 months, significantly greater than the control group (P = 0.0005, P =» 0.01). Within 6 months, pain
improvement in the SPECT-positive group was no longer statistically significant. Tenderness did not correlate with increased
uptake on SPECT scan. Osteoarthritis of the facets was more common in the SPECT-positive patients (P < 0.001), but did not
correspond with sites of increased uptake on SPECT scan. These results suggest that SPECT can enhance the identification of
back pain sufferers likely to obtain short-term benefit from facet joint injection.
KEY WORDS:
Imaging, Bone scan, Spinal pain, Treatment.
IT is thought that low back pain deriving from facet
joints is characterized by local tenderness and pain on
spinal extension and exercise [1-3]. These features have
been endorsed by observing pain distribution after
stimulating the facets [4,5]. However, there are
reservations about such crude clinical criteria. These
doubts could account for the inconclusive results of
previous studies of facet joint injection treatment [6-8].
Identification of facet pathology by X-ray is unhelpful
[9] and CT scans, although more reliable at detecting
structural changes, are unable to distinguish relevant
from incidental abnormalities [2, 10].
Bone scans are sensitive at identifying sites of
skeletal and related tissue pathology, but their
application to back pain has been limited by the
difficulty of determining the precise anatomical
location of activity. Single photon emission computerized tomography (SPECT) is an extension of this
technique and overcomes the problem by rotating the
gamma camera to give a topographical image. This
improves sensitivity by producing better spatial
information and multiplanar views [11, 12]. SPECT has
enabled activity from the posterior elements to be
visualized separately from that arising in vertebral
bodies and, in particular, has enabled activity arising
from the facet joints to be detected [13].
A recent study has suggested that many patients with
chronic low back pain have foci of increased activity
arising from one or more facet joints, as demonstrated
by SPECT [14]. These foci are often associated with
facetal disease on CT scans and may represent the site
of origin of pain [9, 15]. Thus, bone scintigraphy with
SPECT may be a valuable tool for the recognition of
pain arising from facetal disease. This is supported by
studies in which most of those with increased SPECT
uptake at facet joints responded to injection of local
anaesthetic [16, 17].
This study assessed the value of injecting facet joints
showing increased SPECT activity in patients with
clinical features thought to indicate facet disease
(Fig. 1). Our hypotheses were that (i) abnormal SPECT
uptake implies pathology and thus the origin of pain
and (ii) the response to facet injections could be
improved by more precise identification of suitable
patients for treatment.
METHOD
Patients were recruited from the rheumatology
departments of Guy's, Lewisham and the Brook
Hospitals. All had low back pain of at least 3 months
duration and fulfilled the criteria for facet joint pain,
namely, more pain on spinal extension than flexion,
pain relieved by rest and worsened by sitting or
standing and not made worse by coughing or
sneezing. Any patients with signs of nerve root
compression, previous spinal surgery or general ill
health were excluded. Patients gave written consent for
the study and were evaluated with a clinical history and
general examination. Haemoglobin, WBC, ESR and
bone biochemistry were performed to exclude any
inflammatory or metabolic disorder. Sites of tenderness
Submitted 25 January 1996; revised version accepted 29 May 1996.
Correspondence to: T. Gibson, Clinical Rheumatology Unit,
Shepherds House, Guy's Hospital, London SE1 9RT.
© 1996 British Society for Rheumatology
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BRITISH JOURNAL OF RHEUMATOLOGY VOL. 35 NO. 12
were recorded. Spinal flexion was measured by the
modified Schober index [18] and spinal extension as
described by Moll and Wright [19]. Patients completed
a modified McGill Pain Questionnaire (MPQ) [20],
Present Pain Intensity score (PPI) [20] and a Visual
Analogue Score for Pain (VAS). Three assessments of
pain were utilized because none is capable of
encompassing all elements of the pain experience. The
MPQ measures the quality of pain, whereas PPI and
VAS are indications of its intensity. Concomitant
analgesic requirement was noted, but no other
treatment was permitted. X-rays of the lumbar spine
including oblique views were obtained.
AU patients underwent planar bone scintigraphy
followed by SPECT scanning of the lumbar spine.
(a)
Bone scintigraphy was undertaken after i.v. injection of
750 MBq Tc-99m MDP. Planar imaging of the spine
and pelvis was performed after 3 h, followed by SPECT
of the lumbar spine using a rotating gamma camera
equipped with a high-resolution collimator. An
elliptical 360° orbit was used with 64 projections and
20 s per projection. Acquisition was into a 128 x 128
matrix.
X-rays were examined by an independent observer
who was blind to the clinical and scan details. The
presence or absence of facetal joint OA was noted.
Planar and SPECT images were assessed by a nuclear
medicine physician, independent of the clinical or
radiographic data. Only scans which were unequivocally abnormal were counted as positive. Inter- and
POST
(b)
FIG. 1.—(a) Planar bone scan of lumbar spine. No anatomically precise abnormality was seen, (b) Single photon emission tomography (SPECT)
in the same patient showing increased uptake at both L4/5 facet joints.
DOLAN ET AL.: SPECT SCANS IN BACK PAIN
TABLE I
Details of SPECT-positive and SPECT-negative patients on entry to
the study. Figures represent the median (range) or mean (S.E.)
Gender
Age(yr)
Duration (months)
PPI score
McGill pain
VAS (mm)
Extension (cm)
Flexion (cm)
SPECT positive
SPECT negative
7 M 12 F
54(34-66)
3 (3-30)
2.65 (0.28)
28.3 (2.8)
60.1 (4.7)
5.37 (0.64)
5.56 (0.29)
15 M 20 F
41 (18-78)
3 (3-27)
2.82 (0.21)
30.6 (1.3)
58.1 (3.4)
4.98 (0.49)
5.89 (0.29)
intra-observer error were not assessed, and reliance was
placed on the judgement of the nuclear medicine
physician, as is conventional with other imaging
techniques.
Patients with increased SPECT uptake at the lumbar
spine facet joints were injected at these sites with 0.5 ml
of 1 % lignocaine and 40 mg of methylprednisolone, by
an experienced anaesthetist underfluoroscopiccontrol.
A 22 gauge spinal needle was placed in the joint space
during biplanar X-ray screening following local
infiltration of skin and s.c. tissues with 0.5%
lignocaine. Where there was resistance to injection, the
needle was repositioned. If resistance persisted, the
needle was withdrawn to avoid rupture of the joint
capsule. Where the joint space could not be clearly
seen, the injection was placed adjacent to the joint.
Patients with the same clinical pattern, but without
uptake at the facet joints on SPECT, received a similar
injection into the facet joints approximating to sites of
maximal tenderness using the same fluoroscopic
control, and the same size of needle and dose of
corticosteroid. Where in any one patient there was
more than one SPECT-positive site or area of
tenderness, all relevant facets were injected.
Clinical assessments were repeated at 1, 3 and 6
months following injection. Results were analysed
using Mann-Whitney and x2 tests.
RESULTS
Fifty-eight patients were enrolled in the study; 22
had positive SPECT scans and 36 were negative. Five
patients had two active facets and one had three active
sites. Four patients were excluded from analysis: two
because of technically unsuccessful injection (both
SPECT positive) and two because after admission to
the study they developed sciatica and CT evidence of
disc protrusion with root compression (one SPECT
positive and one negative). No follow-up measurements were performed on these cases.
The sex distribution and disease duration were
similar in the two groups, but those who were SPECT
positive were older (Table I). Prior to treatment, there
was no difference in any of the parameters of pain or
spinal mobility. There was no difference between
groups in number of injections or total amount of
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steroid received; the 19 patients with SPECT-positive
scans were injected at 25 sites, the 35 SPECT-negative
patients were injected at 44 sites (average 1.3 sites for
both groups).
Patients with positive SPECT scans showed significant improvement in pain (VAS) at 1 month compared
with SPECT-negative patients (P < 0.05), and with
pre-treatment values at 1 and 3 months (P = 0.002,
P = 0.05). Pain (VAS) did not change significantly in
the SPECT-negative group (Table II).
The McGill pain score in the SPECT-positive group
was significantly better than that in the SPECT-negative group at 1 and 3 months (P = 0.005, P = 0.01)
(Table II). Present pain intensity score improved at 1
month in the SPECT-positive group (P = 0.0005).
Spinal extension and flexion exhibited no significant
change in either group (Table II). At the end of the
study, eight (42%) SPECT-positive and five (14%)
SPECT-negative patients had stopped analgesics
(X2 = 5.2; P = 0.02).
Of those with positive scans, 94% reported
improvement at 1 month, but only 47% of scan-negative patients did so (P = 0.0005). At 3 months, 79%
of those with positive scans reported improvement,
compared with 42% of scan-negative cases. The
number of patients who reported improvement was
significantly greater than the control group at 1
(P < 0.0005) and 3 months (P < 0.01). The statistically
significant improvement of pain evident after 1 and 3
months in SPECT-positive patients had disappeared by
6 months, although mean results were still lower than
pre-treatment values.
Only 3/22 patients with positive scans had a site of
tenderness corresponding to the location of increased
uptake on SPECT.
Suitable oblique spinal X-rays were available on 46
patients and 9/19 (47%) of those with positive SPECT
scans had OA changes at the facet joints, compared to
TABLE II
Effect of treatment on scores of pain and spinal movement in
SPECT-positive and SPECT-negative patients. Results are expressed
as mean (±s.D.)
Time (months)
0
PPI
Pos.
Neg.
VAS
Pos.
Neg.
McGill
Pos.
Neg.
Extension
Pos.
Neg.
Flexion
Pos.
Neg.
2.65 (0.28)
2.82 (0.21)
1
1.4 (OAT)*• •
3.52 (0.95)
3
6
2.15 (0.25)
2.55 (0.19)
2.37 (0.33)
2.76 (0.21)
60.1 (4.7)
58.1 (3.4)
33 (5.9)*
53 (4.3)
42.1 (6.2)
51.7 (4.4)
28.3 (2.8)
30.6 (1.3)
22.1 (1.9)'*
29.03 (1.6)
23.4 (2.7)" 27.2 (2.4)
30.2 (1.9)
29.4 (1.6)
43.8 (5.8)
55.9 (3.9)
5.37 (0.64)
4.98 (0.49)
5.9 (0.65)
6.11 (0.68)
5.9 (0.58)
5.5 (0.57)
6.3.(0.58)
6.14(0.49)
5.56 (0.29)
5.89 (0.29)
5.78 (0.32)
6.03 (0.29)
5.44 (0.28)
5.74 (0.36)
5.56 (0.24)
6.11 (0.35)
*P < 0.05; **P < 0.005; ••*/> < 0.0005.
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BRITISH JOURNAL OF RHEUMATOLOGY VOL. 35 NO. 12
5/27 (18%) of the SPECT-negative group (P < 0.001).
However, only 6/22 (20%) SPECT-positive facets
corresponded with X-ray evidence of OA at these sites.
DISCUSSION
In this study, patients who were injected at sites of
increased uptake on SPECT scans showed significant
improvement at 1 and 3 months for McGill pain score.
Of those with positive SPECT scans, 94% reported
improvement at 1 month. There was no significant
improvement in patients with negative scans.
Mooney and Robertson [3] first reported intra-facet
steroid injection and noted long-term improvement in
52%. Facet joint injection has been used for both
diagnosis and treatment, and long-term improvement
reported in 20-30% [21, 22]. However, Raymond and
Dumas [6] showed that only 16% of patients had
short-term improvement when contrast and local
anaesthetic were confined to the capsule, suggesting
that previous benefits may have arisen by treating a
wider extra-articular area. Controlled studies using
corticosteroid and local anaesthetic injection showed
no benefit over saline [7, 8]. Our study suggests that
SPECT scanning improves patient selection and
localization of the relevant facet joint.
The clinical features of facet pain were originally
defined after the injection of saline into facet joints and
the recognition of similar distributions of pain in a
clinical setting [1, 4, 5]. With the possible exception of
disc pathology, symptoms and signs of low back pain
are often non-specific. We found increased uptake on
SPECT in only 37% of the total who satisfied the
criteria for facet disease. Since the response to injection
was significantly enhanced when directed at a focus of
increased SPECT activity, it would seem that these foci
do locate facet disease.
In our practice, local anaesthetic and steroid
injection are often used to screen patients before facet
denervation [23]. The study has shown the benefit of
local anaesthetic and steroid injection for periods of up
to 6 months, although relapses increased with time.
Those experiencing transient improvement could
benefit from subsequent denervation.
Sites of tenderness had little relationship to increased
uptake on SPECT scan. Thus, reliance on clinical
determination of facet joints suitable for injection is
questionable. Some practitioners inject multiple levels
in order to overcome the imprecision of clinical
assessment, but this is time consuming. Facet joints are
innervated from branches to the posterior primary
ramus at the corresponding level and from the nerve
root above, which may account for the inaccurate
localization of pain.
There was no association between increased uptake
on SPECT scanning and X-ray change at specific facet
joints, although positive scans were more likely to
occur in those with facet OA at other sites. The SPECT
lesion could be an early stage of OA not visible on
X-ray and possibly more steroid responsive. Alternatively, the lesion at the facet joints may not be
degenerative in all cases. Bone scan activity may
indicate hyperaemia, with increased uptake reflecting
an area of inflammation secondary to a mechanical
trigger point. Einstein and Parry [2] have suggested that
facetal pain is the result of a concise arthritic syndrome.
They identified a process of cartilage necrosis,
ulceration and subchondral cysts without osteophytes.
This resembled the changes seen in chondromalacia
patellae.
SPECT scanning is simple and cheap to perform
with modern equipment. It takes ~ 25 min for a
single-headed camera and 15 min for a dual-headed
camera. This study shows that scanning in low back
pain results in improved localization of metabolically
active facet joints and a better clinical outcome after
local steroid injection. Since the clinical criteria of facet
disease are so poor, we advocate SPECT scanning in
all patients with non-discogenic chronic back pain.
Amongst these may be patients who would derive
benefit from facet injection.
ACKNOWLEDGEMENT
We are grateful to the Arthritis and Rheumatism
Council for supporting this study.
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