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Ultrasound Evaluation of
Low Back Pain
J A.
Jon
A Jacobson,
J
b
M
M.D.
D
Professor of Radiology
Director, Division of Musculoskeletal Radiology
University of Michigan
Disclosures:
• Consultant: Bioclinica
• Book Royalties: Elsevier
• Grant: AIUM, Harvest Technologies
Objectives:
1. Recognize sonographic anatomy of
the lumbar spine
2 Understand the difficulties in spine
2.
ultrasound
3. Familiar with various ultrasoundultrasoundguided procedures
1
Introduction:
• Back pain: common
– 2nd leading cause of physician visits
• Causes for back pain: multifactorial
– Disc degeneration
– Nerve impingement
– Facet osteoarthrosis
– Less common: fracture, tumor, infection
Kapellen,, Beall Semin Roentgen 2010; 218
Kapellen
Imaging Evaluation:
• Radiographs: initial evaluation
• MRI: more sensitive
• CT: excellent bone detail
– Radiation concerns
• US:
– Diagnostic: limited, controversial
– Guided intervention
Goal:
• To review the role of
musculoskeletal ultrasound in
evaluation on low back pain
• Discuss controversies
• Review ultrasound
ultrasound--guided
interventional procedures
2
Ultrasound Technique
• If superficial:
– Paraspinal muscles
– >10 MHz, linear or curvilinear
• Other:
– Facet and bone anatomy
– <10 MHz curvilinear
Anatomy:
• Bone landmarks: critical
• Lumbar spine:
– Surface
S rface bone anatom
anatomy is comple
complex
– Some landmarks are small
– Limited resolution with increased
depth
Anatomy
3
Needle Guidance:
• Free hand:
– Direct (visualize needle)
• In
In--plane of transducer:
transducer: best
• Out
Out--ofof-plane: superficial targets
Technique:
• Transducer orientation
– In plane approach
– Long axis of needle
along long axis of
transducer
– Always see entire
needle including tip
In Plane
Approach
4
In Plane Approach
Out of Plane
Approach
Out of Plane
Approach
5
Out of Plane
Approach
Out of Plane Approach
Superficial joints:
•AC, SI, CMC, MCP, PIP, DIP
Outline:
•
•
•
•
•
•
Paraspinal musculature
Facet joint
Medial branch block
Caudal epidural
Sacroiliac joints
Piriformis
6
Paraspinal Musculature:
• Seen well with ultrasound
– Limited with large body habitus
–S
Significant
g
atrophy:
p y echogenic
g
• Pathology:
– Abscess
– Hematoma
– Mass
Abscess:
•
•
•
•
•
Usually hypoechoic or anechoic
Variable echogenicity: heterogeneous
May be hyperechoic
Posterior throughthrough-transmission
Swirling of contents: transducer
pressure
Paraspinal Abscess
7
Paraspinal Abscess
Aspiration
Hematoma:
•
•
•
•
•
Variable echogenicity
Acute: hyperechoic, variable
Subacute - chronic: hypoechoic
yp
Seroma
Seroma:: anechoic
Heterotopic ossification:
– Echogenic, shadowing
– Consider CT to confirm
Hematoma
Color Doppler
8
Heterotopic Ossification
Lipoma::
Lipoma
• Well
Well--defined
• If subcutaneous:
– Oval, isoechoic to hyperechoic
– Compressible
C
ibl
– No flow on color or power Doppler imaging
• If intramuscular:
– Variable echogenicity
– Usually get MRI to confirm
Lipoma
Color Doppler
9
Miscellaneous Masses:
• Hemangioma (venous malformation):
– Mixed hypoechoic and hyperechoic
– Flow in multiple vessels
• Malignancy
– Usually hypoechoic
– Variable flow on color / power Doppler
– MRI for extent and characterization
– US: biopsy guidance
Hemangioma (Venous Malformation)
Color Doppler
Lymphoma
CT
Biopsy
10
Outline:
•
•
•
•
•
•
Paraspinal musculature
Facet joint
Medial branch block
Caudal epidural
Sacroiliac joints
Piriformis
Facet Joints:
• Can be identified when normal
• Difficult to see with osteophytes or
with large body habitus
• Understanding of bone surface
anatomy is key
Spinous Processes
L3
L3
L4
L4 vertebral body
L4
L3
L4
11
Lateral Masses
L3/4
Facet
L4/5
Facet
L3
L4
L4
L3
L4
Transverse Processes
L5
L4
Lumbar Spine: sagittal
Note:: inferior aspect of
Note
spinous process aligns
with inferior facet, which
is just superior to lower
transverse process
• L3 spinous process
• L3/4 facet
• L4 transverse process
12
Transverse Process
*This
This is not the facet joint
Mamillary
Process
Accessory
Process
Facet Joints
Note: absence of transverse process
Lamina
*This is not the facet joint
13
Lumbar Spine: axial
1. Start at transverse
process at desired
level
2. Move superior to see
superior facet
3. Move inferior to
lamina and then to
inferior facet
Facet Joint: injection steps
• Start in sagittal plane over midline
1. Identify spinous processes, proper level
• Turn transducer 90 degrees
2. Identify contours of transverse process
3. Move superior to find superior facet joint
• Transverse process: not in view
Facet Joint: injection
Facet Joint Space: 2 ml
14
Facet Joints: diagnostic US
• 59 subjects + 23 controls
– Increased echogenicity = inflammation
• Results:
– Ultrasound no better than chance
– Poor reproducibility
• US should be considered investigational
in the diagnostic evaluation of facet joints
Nazarian et al. J Ultrasound Med 1998; 17:117
17:117--122
Facet Joint: injection
•
•
•
•
50 facet joints (cadavers)
CT gold standard
Successful in 84% (42/50)
Error:
– Inaccurate identification of facet joint
– Due to mamillary and accessory processes
Galiano K et al. Anesth Analg 2005;101:579
2005;101:579--583
Accessory and Mamillary Processes
15
Inaccurate Facet Joint: injection
ap = accessory process
mp = mamillary process
* is not the facet joint
Note:
Lamina
Imaging at level of
transverse process
From: Galiano K et al. Anesth Analg 2005;101:5792005;101:579-583
Normal Facet Joint
From: Galiano K et al. Anesth Analg 2005;101:5792005;101:579-583
Facet Joint: injection
3 – 4 cm
Note:
Interlaminar
Space
Note:
Interlaminar
Space
From: Galiano K et al. Anesth Analg 2005;101:579
2005;101:579--583
16
Facet Joint: injection
• 18 patients
• US
US--guidance with CT as gold standard
– 11% ((2/18):
) could not see facet joints
j
(large body habitus)
– 11% (2/18): partial visualization of facet
(only 1 was needle was accurate)
Galiano K et al. Reg Anesth Pain Med 2007; 32:317
32:317--322
Facet Joint: osteoarthritis
Osteophyte
Osteophyte
From: Galiano K et al. Reg Anesth Pain Med 2007;32:254
2007;32:254--257
US--guided Facet Injections
US
• US: decreased accuracy
– Osteoarthritis
– Large
g body
y habitus
• CT: most accurate in all situations
• Should injection be in facet joint?
• Is CT or MRI still needed to assess
which level to inject?
17
Outline:
•
•
•
•
•
•
Paraspinal musculature
Facet joint
Medial branch block
Caudal epidural
Sacroiliac joints
Piriformis
Peripheral Nerves:
• US: hypoechoic nerve fascicles
• Effective: when superficial and
visible
• Very difficult: small, deep nerves
– Lumbar spine
Nerve Roots: diagnostic US
• 59 subjects + 23 controls
– Increased echogenicity = inflammation
• Results:
– No better than chance
– Poor reproducibility
• US should be considered investigational
in the diagnostic evaluation of nerve roots
Nazarian et al. J Ultrasound Med 1998; 17:117
17:117--122
18
Medial Branch Block:
• Used to diagnose and treat facet jointjointrelated pain
• Guidance:
– Fluoroscopy
– CT
– Ultrasound
• Use of bone landmarks
Medial Branch: anatomy
• Medial branch of dorsal ramus:
– Superior border of transverse process
– Runs along junction of transverse
process and superior articular facet
– Turns medial under base of facet joint
under mamillo
mamillo--accessory ligament
Kapellen,, Beall Semin Roentgen 2010; 218
Kapellen
Dorsal Ramus Branches
Lateral Branch:
Branch:
Iliocostalis
Skin: lumbar,
upper lateral buttock
Intermediate Branch:
Branch:
Longissmus
From: Kapellen,
Kapellen, Beall
Semin Roentgen 2010; 218
Medial Branch:
Branch:
Facet joint
Interspinous ligament
Spinous process
Multifidus muscle
Ligamentum flavum
19
Medial Branch:
• Injection target:
– Transverse
process and
superior articular
facet
Medial Branch: injection
• Cadaveric and clinical study:
– 120 facet injections using fluoroscopy & CT
• Injection between transverse
process and superior facet
– Accurate
– Inferior location: less aberant injection
– 0.5 ml injection: adequately bathed nerve
Schwarzer,, et al. Spine 1997; 22:895
Schwarzer
Medial Branch: injection
From: Schwarzer,
Schwarzer, et al.
Spine 1997; 22:895
20
Medial Branch Injection
Medial Branch Block:
• Cadaver: 3 injections
– Accurate in all 3
• Imaging:
– 20 volunteers
– Bone landmarks difficult in 1: body habitus
• Clinical study:
– 28 injections under ultrasound
– Fluoroscopic confirmation
– 25/28 accurate; 3/28: within 5 mm
Greher,, et al. Anesthesiology 2004; 100:1242
Greher
Medial Branch Injection
From: Greher
Greher,, et al.
Anesthesiology 2004;
100:1242
21
Medial Branch Block:
• Clinical study:
– 101 injections in 20 patients
– Ultrasound guidance
– Fluoroscopic confirmation
– 95% (96/101): accurate
– In 2/101: intravascular injection
Shim, et al. Reg Anesth Pain Med 2006; 31: 251
Outline:
•
•
•
•
•
•
Paraspinal musculature
Facet joint
Medial branch block
Caudal epidural
Sacroiliac joints
Piriformis
Caudal Epidural Injection:
• For anesthesia of lumbar and sacral
dermatomes
• Blind injection failure rate: up to 25%
• Imaging guidance:
– Fluoroscopy
– Ultrasound
Chen, et al. Anesthesiology 2004; 101:181
22
Sacral Hiatus
From: Chen, et al. Anesthesiology 2004; 101:181
Caudal Epidural Injection:
• Clinical study1:
– 70 patients
– Fluoroscopic
p confirmation
– 100% (70/70): accurate
• Variations2
– Absent hiatus: 4%, bony septum: 2%
1Chen,
et al. Anesthesiology 2004; 101:181
et al. Clin J Pain 2004;
2004; 20:51
2Sekiguchi,
Caudal Epidural: guidance
• Transducer: linear around 10 MHz
– Sagittal to body
• N
Needle:
dl iin plane
l
tto ttransducer
d
• Direction: inferior to superior
• 20 – 22 gauge needle
23
Caudal Epidural Injection
Short Axis
From: Chen, et al. Anesthesiology 2004; 101:181
Outline:
•
•
•
•
•
•
Paraspinal musculature
Facet joint
Medial branch block
Caudal epidural
Sacroiliac joints
Piriformis
Sacroiliac Joints:
• Limited evaluation:
– Narrow joint with small recess
– More difficult when abnormal: osteophytes
• Sacroiliitis
Sacroiliitis::
– Can see joint recess distention
– Hyperemia
– Guide aspiration
24
Sacroiliac Joints
Fibrous
Articulation
Synovial
Articulation
SI Joint: US steps
• Start in transverse plane over midline
1. Identify spinous processes, proper level
• Move transducer lateral to see
posterior ilium
• Move inferior
2. Identify posterior sacral foramina
3. Identify SI joint
Normal SI joints: superior
Sacral Foramen
Note: fibrous articulation
25
Normal SI joints: inferior
Midline
Note: true synovial joint
Sacroiliac Joints: anatomy
• Upper aspect
– Fibrous articulation
– Not the true joint
• Lower aspect
– Synovial articulation
– True joint
SI joint: anatomy
From: Pekkafall,
Pekkafall, et al. J Ultrasound Med 2003; 22:553
26
Sacroiliac Joints:
• May see joint effusion /
synovitis
• Hyperemia and
enhancement:
inflammation
• Decreased flow with
treatment ((ankylosing
ankylosing
spondylitis)
From: Ann Rheum Dis 2009; 68:1559
From: Arthritis Rheum 2009; 61:909
Sacroiliac Joints: guidance
• Transducer: curvilinear <10 MHz
– Transverse to body
• N
Needle:
dl iin plane
l
tto ttransducer
d
• Direction: medial to lateral
• 20 – 22 gauge needle: 1 – 2 ml
Sacroiliac Joints: guidance
• Pitfalls
– Synovial portion: inferior aspect
– Sacral foramina
– Osteophytes
27
Sacroiliac Joint: injection
• Clinical study: ultrasound guidance
– 60 injections in 34 patients
– CT gold standard
– 77% (47/60) were intraintra-articular
– Success rate improved: 60% to 94%
Pekkafall,, et al. J Ultrasound Med 2003; 22:553
Pekkafall
SI joint: US
US--guidance
From: Pekkafall,
Pekkafall, et al. J Ultrasound Med 2003; 22:553
Sacroiliac Joint: injection
• Cadaver study: 20 injections
– 7/10 upper and 9/10 lower level
– 4/10: failed, narrowing osteophytes
• Clinical study: 10 patients
– 100% success (8 lower
lower,, 2 upper level)
– Pain relief: 8.6 at 6 months
Klauser,, et al. Arth Care Res 2008; 59:51618
Klauser
28
SI joint
S
Sacral
l
Foramen
From: Klauser
Klauser,, et al. Arth
Care Res 2008; 59:51618
Out of Plane
Approach
Sacroiliac Joint: injection
• Clinical study: 20 injections
– MRI gold standard
– Only
y 40% ((8/20)) were in SI jjoint
– No significant difference: pain relief
– Experience and background of person
performing US not indicated
Hartung,, et al. Rheumatology 2010; 49:1479
Hartung
29
Outline:
•
•
•
•
•
•
Paraspinal musculature
Facet joint
Medial branch block
Caudal epidural
Sacroiliac joints
Piriformis
Piriformis Syndrome:
• MRI findings:
– Sciatic nerve edema
– Displaced
p
sciatic nerve
– Piriformis muscle hypertrophy
– Aberrant course: sciatic or peroneal nerve
– No abnormalities
Pacina HI et al. Skeletal Radiol 2008
2008;; 37:1019
Piriformis Syndrome:
• Injection:
– Steroids
Steroids,, anesthetic,
anesthetic, botulinim toxin
• Muscle injection1
– Ultrasound more accurate that fluoroscopy2
• Peri
Peri--sciatic infiltration3
1Peng
2Finoff
PW et al. Pain Physician 2008; 11:215
JT et al. J Ultrasound Med 2008; 27:1157
3Reus M et al. Eur Radiol 2008; 18:616
30
Piriformis Injection:
• Technique:
– Low frequency curvilinear transducer
– Axial plane
– Move transducer inferior to SI joint
– Angle transducer: inferior and lateral
– Rotate hip internally: movement of tendon
Finoff JT et al. J Ultrasound Med 2008; 27:1157
Piriformis
GMx
GT
Ischium
Lateral
Medial
Long Axis
Piriformis
Medial
Lateral
Long Axis
31
Piriformis: injection
GT
Ischium
Lateral
Medial
Long Axis
Take Home Points:
• Diagnostic US for lower back:
– Limited to paraspinal muscle pathology
• US
US--g
guidance for interventional p
procedures:
– Must know bone landmarks
– Difficult: depth, complexity of spine
– Must be able to track needle
– How much accuracy is required?
32