Ultrasound Evaluation of Low Back Pain Jon A. Jacobson, M.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 ultrasound 3. Familiar with various ultrasound- guided procedures 1

Introduction: Back pain: common 2 nd 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 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-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 bone anatomy is complex Some landmarks are small Limited resolution with increased depth Anatomy 3

Needle Guidance: Free hand: Direct (visualize needle) In-plane of transducer: best Out-of-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 Significant Sg atrophy: echogenic Pathology: Abscess Hematoma Mass Abscess: Usually hypoechoic or anechoic Variable echogenicity: heterogeneous May be hyperechoic Posterior through-transmission transmission Swirling of contents: transducer pressure Paraspinal Abscess 7

Paraspinal Abscess Aspiration Hematoma: Variable echogenicity Acute: hyperechoic, variable Subacute - chronic: hypoechoic Seroma: anechoic Heterotopic ossification: Echogenic, shadowing Consider CT to confirm Hematoma Color Doppler 8

Heterotopic Ossification Lipoma: Well-defined If subcutaneous: Oval, isoechoic to hyperechoic Compressible 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 L4 L3 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 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 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: 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; 17:117-122122 Facet Joint: injection 50 facet joints (cadavers) CT gold standard Successful in 84% (42/50) Error: Error: Inaccurate identification of facet joint Due to mamillary and accessory processes Galiano K et al. Anesth Analg 2005;101:579-583583 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;101:579-583 583 Normal Facet Joint From: Galiano K et al. Anesth Analg 2005;101:579-583 583 3 4 cm Facet Joint: injection Note: Interlaminar Space Note: Interlaminar Space From: Galiano K et al. Anesth Analg 2005;101:579-583583 16

Facet Joint: injection 18 patients US-guidance with CT as gold standard 11% (2/18): could not see facet joints (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; 32:317-322322 Facet Joint: osteoarthritis Osteophyte Osteophyte From: Galiano K et al. Reg Anesth Pain Med 2007;32:254-257257 US-guided Facet Injections US: decreased accuracy Osteoarthritis Large body 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: 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; 17:117-122122 18

Medial Branch Block: Used to diagnose and treat facet joint- related 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-accessory accessory ligament Kapellen, Beall Semin Roentgen 2010; 218 Dorsal Ramus Branches Lateral Branch: Iliocostalis Skin: lumbar, upper lateral buttock Intermediate Branch: Longissmus From: Kapellen, Beall Semin Roentgen 2010; 218 Medial 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 Medial Branch: injection From: 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 Medial Branch Injection From: 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 study 1 : 70 patients Fluoroscopic confirmation 100% (70/70): accurate Variations 2 Absent hiatus: 4%, bony septum: 2% 1 Chen, et al. Anesthesiology 2004; 101:181 2 Sekiguchi, et al. Clin J Pain 2004; 20:51 Caudal Epidural: guidance Transducer: linear around 10 MHz Sagittal to body Needle: in plane to transducer 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: Can see joint recess distention Hyperemia Guide aspiration Sacroiliitis 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, 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 spondylitis) enhancement: From: Ann Rheum Dis 2009; 68:1559 From: Arthritis Rheum 2009; 61:909 Sacroiliac Joints: guidance Transducer: curvilinear <10 MHz Transverse to body Needle: in plane to transducer 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 intra-articular articular Success rate improved: 60% to 94% Pekkafall, et al. J Ultrasound Med 2003; 22:553 SI joint: US-guidance From: 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, 2 upper level) Pain relief: 8.6 at 6 months Klauser, et al. Arth Care Res 2008; 59:51618 28

SI joint Sacral Foramen From: Klauser, et al. Arth Care Res 2008; 59:51618 Out of Plane Approach Sacroiliac Joint: injection Clinical study: 20 injections MRI gold standard Only 40% (8/20) were in SI joint No significant difference: pain relief Experience and background of person performing US not indicated Hartung, et al. Rheumatology 2010; 49:1479 29

Outline: Paraspinal musculature Facet joint Medial branch block Caudal epidural Sacroiliac joints Piriformis Piriformis Syndrome: MRI findings: Sciatic nerve edema Displaced sciatic nerve Piriformis muscle hypertrophy Aberrant course: sciatic or peroneal nerve No abnormalities Pacina HI et al. Skeletal Radiol 2008; 37:1019 Piriformis Syndrome: Injection: Steroids, anesthetic, botulinim toxin Muscle injection 1 Ultrasound more accurate that fluoroscopy 2 Peri-sciatic infiltration 3 1 Peng PW et al. Pain Physician 2008; 11:215 2 Finoff JT et al. J Ultrasound Med 2008; 27:1157 3 Reus 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 Long Axis Medial Piriformis Medial Long Axis Lateral 31

Piriformis: injection GT Lateral Ischium Long Axis Medial Take Home Points: Diagnostic US for lower back: Limited to paraspinal muscle pathology US-guidance for interventional procedures: Must know bone landmarks Difficult: depth, complexity of spine Must be able to track needle How much accuracy is required? 32