Backache Imaging Presentation Hieder A`ala 601 MUST University
Wasted time? Radiology departments do lots of imaging for low back pain. X-rays, CT, MRI etc. How much makes a difference? Studies show advanced imaging in acute back pain and sciatica doesn’t change outcomes, but improves diagnostic confidence.
Causes of back pain andsciatica Paraspinal muscles Spondylosis and ligaments Spinal stenosis Synovial joints: Foraminal stenosis Facet and sacroiliac Bone disease joints Tumor Disc disease Fracture Tear of annulus Infection fibrosis Epidural abscess Specific nerve root discitis impingements
Acute Back Pain 2nd most common complaint to primary care physician >75% of adults will suffer it at some time. 90% will resolve without intervention (or imaging), most without a specific dx. Among patients with sciatica, only <10% will need surgery. Whom to image?
Back pain imaging — falsepositives Most adults over 40 will have degenerative changes on x-rays MRI shows disc pathology in the majority of adults Many asymptomatic people have disc bulges and protrusions. So, imaging is likely to result in an abnormal report. But correlation between radiographic findings and clinical symptoms is poor. When to image?
When to image in patients with acute back pain? Most authorities suggest conservative treatment for 4-6 weeks unless there are “red flags”: Look for historical and physical findings that raise clinical question of infection, tumor, or serious neurological impairment Even positive findings of degenerative disease like disc extrusions and spinal stenosis are not urgent and will be treated conservatively at first.
“Red flags” for early imaging Severe progressive neurological deficit Fracture? Major trauma or minor trauma in osteoporotic pt. Tumor? History of cancer, weight loss Pain worse at night or when supine Infection? Recent bacterial infection, immune supression, fever, IVDA
Imaging options Radiography CT Better for fine bone detail, arthritis As good as MRI for acute disc disease Myelography as adjunct MRI Very good for disc, paraspinal pathology, stenosis Infection Marrow disorders Contrast for infection, post-op, tumor Bone scan Not for primary imaging in most cases Discography
Radiography AP and lateral films Oblique films Flexion / extension films
Radiography Diagnoses that can be made on AP and lateral: Spondylolisthesis Compression fracture SI joint disease Disc degeneration Facet arthritis Tumor Infection in disc space
Radiography Diagnosis best made on oblique films: Spondylolysis Facet joints Facet arthritis Foraminal stenosis (cervical spine)
Radiography Diagnosis made with flexion / extension films: instability
Spondylolysis Stress fracture through pars interarticularis If bilateral, can cause spondylolisthesis Sagittal reformatted CT spondylolysis spondylolisthesis
Cross Sectional Imaging: CT and MRI Why? Confirm extent of degenerative disease and spinal stenosis. Search for confirmatory findings in patient with a specific radiculopathy if surgery is contemplated. Occult back pain not responding to conservative treatment Rule out tumor or infection in appropriate patients
Anatomy (see hieder lecture on radiological anatomy ) T1 T2 Conus medullaris Cauda equina
Disc disease After age 40, most adults have at least some desiccation and loss of height of lumber discs: Low signal on T2 images. Posterior or diffuse bulges and protrusions are common. Jelly-like nuclear material leaks out through tear in annular fibers.
Glossary of disc pathology terms Herniation: nonspecific term subject to misinterpretation. Not recommended. Bulge: diffuse enlargement of disc area Very common Usually not clinically important May contribute to spinal stenosis Protrusion: nucleus pulposus pushes focally through fibers of annulus fibrosis Base wider than apex May focally impinge on nerve or thecal sac
Glossary of disc pathologyterms Extrusion: nucleus material pushes out beyond posterior longitudinal ligament but remains in contact with disc space Apex wider than base Likely to impinge on nerve roots Sequestration: Disc fragment isolated from parent disc
Glossary of disc pathologyterms Localizing terms: Central Paracentral Foraminal Lateral
Spinal stenosis Symptoms Neurogenic claudication Pain relieved with sitting, bending forward Progressive pain +/- radiculopathy, cauda equina syndrome +/- low back pain No specific measurement to define it in the lumber spine. Many improved with nonsurgical therapy
Spinal stenosis Contributing factors: Disc bulges and protrusions Facet arthropathy Ligamentum flavum hypertrophy Posterior vertebral body osteophytes Anterior and lateral osteophytes generally not important Spondylolisthesis Not spondylolysis alone
Spondylosis (Degenerative Disease) Sag T2 Axial T2 Axial CTAnnular disc bulge and facet arthropathy cause spinal stenosis
Spondylosis causing spinal stenosis Compressed 5 :1 Compressed 5 :1 Page: 11 of 18 IM: 11 SE: 5 cm cm Page : 8 of 18 18 IM: 8 SE: 5 cm cm Compressed 5 :1Page: 6 of 11 IM: 6 SE: 3 cm cm Compressed 5 :1 Page: 13 of 18 13 IM: 13 SE: 5 cm
What does that report mean? Facet disease: Common in older patients May cause pain radiating to hip, simulating sciatica Predisposes to dynamic instability Contributes to spinal and foraminal stenosis Mild disc bulges or protrusions Very common incidental findings Focal sciatica Spinal stenosis only if large or in combination with other factors (formerly asx stenosed canal) Usually not significant unless good correlation with sx.
What does that report mean? Look for key words and descriptions: “spinal stenosis”, “foraminal stenosis” Nerve root “displacement”, “compression” or “impingement” (see lecture of nomenclature) Is a specific root involved? Does it correlate with symptoms?
What to order: MRI or CT MRI generally preferred Contraindications to MRI? — CT is an acceptable substitute for disc and bony disease, but poor for infection or intrathecal tumor. MRI — IV contrast only for: Suspected infection Suspected tumor Post-operative spine Recurrent disc vs. scar tissue
Spinal and Epidural Infection High risk populations: Immunocompromised AIDS Transplant Chemotherapy Endocarditis or sepsis Postoperative patients especially with hardware (instrumentations) Tuberculosis: not necessarily immune compromised
Bacterial discitis T1 Axial With GDT1 Sag T2 Sag
Tuberculous spondylitis with epidural abscess Enhancing vertebral body Non-enhancing fluid in disc space and epidural spaceT1 with Gd T2
IV drug user– paraspinalabscessT1 unenhanced T1 enhanced T2 unenhanced
Compression fracture:Benign or malignant? Often difficult to distinguish cause of acute compression fracture History of osteoporosis? Osteoporosis may indicate multiple myeloma in patient without risk factors. History of primary tumor? MRI good for survey of marrow at other levels to look for other metastases Bone scan may serve same function
Compression fracture:Acute or chronic? Many patients have unsuspected old compression fractures: Cheapest evaluation: check old films! Bone scan can prove a fracture is old May remain positive for up to two years In elderly, may not be positive in first day MRI can detect acute marrow edema
Compression Fracture—new or old? • New • Hypointense T1 • Hyperintense T2 Easily missed if only T2 Sequence used • Chronic • Same marrow signal as other vertebral bodies on all pulse sequences T1 T2
Metastatic disease On T1 weighted images, discs should be darker than marrow tissue Tumor brighter on T2 weighted images, enhances with contrast Exception—sclerotic prostate metastases