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245 Cards in this Set
- Front
- Back
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What is myelopathy?
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-Results from compromise of the spinal cord
-Caused by mechanical compression, intrinsic lesions, or inflammatory processes (“myelitis”) |
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Symptoms of myelopathy?
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-Bladder and bowel incontinence, spasticity, weakness, ataxia, positive Babinski
-A specific level may develop, but is not always present -Usually the lesions is several levels higher than anticipated |
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What are the most common disease processes causing myelopathy?
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-Epidural masses causing compression
-Cervical spinal stenosis Intramedullary disease—tumor, inflammation, AVM, SDAVF |
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How long can myelopathy be present before permanent damage occurs?
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24 hrs
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What is radiculopathy?
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Impingement of the spinal nerves, either within the spinal canal, lateral recess, or neural foramen, or along the extraforaminal course of the nerve
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Symptoms of radiculopathy?
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Specific dermatomal sensory deficits and/or muscle group weakness
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Most common causes of radiculopathy?
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-Osteophytic spurring (especially cervical spine)
-Disk herniations -Lumbar spinal stenosis |
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Who gets CT myelograms these days?
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-Complex post-op cases
-Patients in whom MR is contraindicated |
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What contrast agent must NEVER be given for myelography? Why?
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-Ionic contrast agents
-They induce severe inflammation, seizures, arachnoiditis, even death -Always personally inspect the vial of contrast you are using and fill the syringe yourself |
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How much contrast should you use for a CT myelogram?
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-Depends of the region and the size of the patient
-Do not exceed 3 g of iodine, you can do the calculations to find out how much that is. |
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How do you decide what concentration of contrast to use in a CT myelogram?
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-Lumbar myelography uses the less concentrated contrast
-Cervical uses the higher concentrations (200-300mg/ml) |
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Why should you do lumbar punctures in the mid-line?
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-To avoid extra-arachnoid injection
-To avoid spearing an exiting nerve root |
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Why should you carefully avoid air bubbles in myelography?
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Because they can look just like drop mets
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Why are C1-C2 punctures so dangerous?
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Direct injury to the cord or a low-lying PICA can occur
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How are C1-C2 punctures done?
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-Using lateral fluoscopy
-Needle is placed in the posterior third of the spinal canal between C1-C2 |
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Indications for cervical puncture?
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-Known blocks caudally…previously identified on lumbar myelography, in a patient with a pacemaker
-Need for dense opacification of the cervical and upper thoracic spine |
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Three spaces for lesions in the spine?
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-Intramedullary
-Intradural-extramedullary -Extradural |
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What does the cord look like with an intramedullary tumor?
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-The cord appears widened in all views
-The CSF spaces appears thinned on all sides in all views |
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Differential for intramedullary lesion?
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“SAME HEAL”
-Synringohydromyelia -Astrocytoma -Multiple sclerosis -Ependymoma -Hemangioblastoma -Epidermoid -AVM -Lipoma Rare site for met or abscess |
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What does the cord look like with an intradural/extramedullary tumor?
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-“marble on a carpet”
-Contrast/CSF forms acute angles with the mass |
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Differential diagnosis of an extramedullary-intradural tumor:
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Your mnemonic is "SAME HEAL" (see SAME HEAL mnemonic for intramedullary tumors too)
-Schwannoma/neurinoma -AVM -Meningioma or Met (drop) -Ependymoma (myxopapillary) -Hemangiopericytoma -Epidermoid -Arachnoid cyst/adhesion -Lipoma/epidermoid |
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Appearance of an extradural mass?
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-CSF/contrast forms obtuse angles under the mass
-The dura and the sac will be displaced together, away from the mass |
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Differential for extradural mass?
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-Degenerative
-Herniated disc -Synovial cyst -Osteophyte -Rheumatoid pannus -Nondegenerative -Metastasis -Abscess -Hematoma -Primary tumor expansion or invasion -Epidural lipomatosis |
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What’s the main indication for spinal angiography?
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Spinal AVM
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Why does MR tend to over-estimate neuroforaminal narrowing?
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Physiologic and patient motion both exaggerate osseous encroachment of the spinal canal and neural foramina
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Give examples of how gadolinium can be confusing in spine MR a give ways to solve them:
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-It may obscure vertebral mets by making them isointense with the surrounding marrow fat
-Use fat saturation -It makes it difficult to evaluation hemorrhage -Always obtain precontrast T1 images |
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How does diffusion imaging help in the spine?
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-It can help with vertebral body mets versus compression fractures
-Tumors show diffusion restriction while fractures do not |
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Why is ultrasound of the spine doable in neonates?
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Because their posterior elements are not ossified and provide a window through which spine anomalies can be evaluated
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What does “transverse myelitis” mean?
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-When clinical and pathologic findings are confined to a distinct level
-This is not really a specific disease, but rather a category of diseases -Don’t use this term in reports since it’s nonspecific |
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Most common cause of intramedullary lesions on MR?
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Multiple sclerosis
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How is spinal MS different from brain MS?
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-When spinal MS predominates, it tends to follow a progressive clinical course, as opposed to relapsing/remitting pattern
-Most MS patients have both spine and brain lesions |
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Where do most MS spine lesions occur?
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2/3rds occur in the cervical spine
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What do acute spinal MS lesions look like?
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Subtle increase in cord diameter because of edema
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What do “burnt out” MS lesions of the spine look like?
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Myelomalacia—“cord softening” or atrophy
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Why do MS plaques tend to be peripheral?
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Because the white matter is on the outside of the cord
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How can you tell the difference between a spinal MS lesion and a glial tumor?
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-It can be difficult
-MS plaques are typically shorter than two vertebral segments in length and involve less than half the cross-sectional area of the cord |
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What should be done whenever mysterious T2 bright lesions are seen in the spine?
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-Get MRI of the brain—“look upstairs”
-The brain and spinal cord are composed of the same tissue, are physically connected, and share CSF |
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How does lupus affect the cord (mechanism)?
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-A necrotizing arteritis can lead to cord ischemia and injury
-Antibodies may also damage neuronal elements directly |
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What do lupus lesions of the spine look like?
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Cord swelling and edema
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How do lupus lesions look different from MS lesions?
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-Lupus lesions have less well-defined margins than the discrete plaques of MS
-They are larger, involving four to five vertebral body segments -Also, lupus lesions improve dramatically with steroids while MS lesions improve less dramatically |
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How does RA cause C1-C2 instability?
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Focal inflamamtion (pannus) can destroy the transverse ligament of C1, allowing the odontoid to slide posteriorly
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When is the cord compressed with C1-C2 instability?
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In flexion
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What does C1-C2 instability of RA look like?
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Intermittent cord compression leads to myelomalacia
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What percent of RA pts have cervical spine ds?
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60%
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Usually, RA pts with cervical spine findings will already have disease in their hands or feet. Why is this an important point?
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Because a soft tissue mass at C1-C2 does not necessarily imply RA
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What can cause a soft tissue mass at the C1-C2 articulation?
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-Pannus of RA
-Fibrous pseudotumor can occur in the same location with an os odontoideum and can develop in response to any chronically unstable spinal anatomy, including an ununited type 1 dens fracture |
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When does radiation myelitis occur?
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6-18 months following initial treatment
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What does radiation myelitis look like?
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Increased signal on T2
Variable enhancement |
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Why is radiation myelitis important (and might necessitate a call to the clinician)?
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It can lead to paralysis
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What do radiation changes look like in the vertebral bodies?
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The normal marrow is destroyed and replaced by fat, making the vertebrae very homogeneously bright on T1
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What can radiation do to the vertebral bodies in children?
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It can kill the osteoblasts in the physes causing stunted growth
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What cells are injured by polio?
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The anterior horn cells
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What does zoster of the spine look like?
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During an active outbreak, cord swelling and edema at the affected levels
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How can measles affect the cord?
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It can cause SSPE leading to demyelination
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How does ADEM affect the cord?
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Monophasic postviral demyelination
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So what’s the difference between transverse myelitis related to postviral syndromes and Guillain Barre?
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There’s not really a difference
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How does HIV affect the cord?
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It directly causes vacuolar changes in the spinal cord
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How does neurosarcoid present in the cord?
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Diffuse leptomeningeal granulomatous nodules which typically enhance
Intramedullary or vertebral body granulmatous changes |
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What entities does neurosarcoid look like?
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Carcinomatosis and mycobacterial meningitis
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Most common causes of arachnoiditis?
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Iatrogenic—inflammation after spine sugery, spinal anesthesia, or epidural nerve
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What does arachnoiditis look like?
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The normal free-layering lumbar roots become adherent to each other or to the peripheral wall of the thecal sac, giving the sac a bald appearance
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What does vitamin B12 deficiency cause?
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Degeneration of the posterior columns
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How do most spine infections start?
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-The organism is seeded via an arterial route
-Pts with dysraphism or those post-op after spine surgery can have direct seeding |
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What is the difference between adult and pediatric blood supply to the disks?
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-Adult disks have relatively poor blood supply, so primary infection is rare
-In children, arteries penetrate the growing disk, providing a direct route for hematogeneous primary infection |
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What part of the vertebral body gets hematogenously seeded?
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The portions near the endplates which have the richest blood supply
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What does vertebral osteomyelitis look like?
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-Loss of marrow signal on T1’s
-Loss of endplate definition -As pyogenic infection breaks through the endplate into the disk, discitis ensues with inevitable infection of the adjacent vertebral body |
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What is the osteomyelitis/diskitis combo called?
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-Pyogenic spondylodiscitis
-This pattern is highly suggestive of infection and unusual with neoplasms |
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Where does an infection head after the vertebral body and disc are involved?
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-The epidural space (causing epidural abscesses)
-Paraspinous soft tissues e.g., psoas muscle |
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What do epidural abscesses look like?
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They look more like phlegmons; they’re not well-encapsulated
-They tend to be posteriorly located -Lower thoracic and lumbar sites are most common |
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How do epidural abscesses evolve over time?
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They spread craniocaudally, extending as many as three to four interspaces away from the vertebral abnormality, which is unusual with neoplasms
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Complications of epidural abscesses?
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Cord compression—they don’t have much room to expand
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What are subdural empyemas associated with?
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-They’re rare
-Associated with surgery or other violation of the dura -That’s fortunate because they can easily spread through the arachnoid layer, resulting in meningitis |
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What’s the most sensitive imaging test for meningitis?
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-Contrast enhanced MR
-A negative MR does not exclude meningitis and should never delay or substitute a lumbar puncture |
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How can the pattern and number of affected vertebrae help you distinguish between infection, tumor, and osteoporosis?
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-Infection rarely involves a single vertbra, and usually it’s at least two vertebrae surrounding an infected disk (pyogenic) or an intact disk with subligamentous spread (tuberculosis or fungus)
-Neoplasm tends to involve one vertebra with noncontiguous involvement being common -Osteoporosis has several vertebrae with height loss |
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How can the portions of vertebrae affected help you distinguish infection vs. tumor vs. osteoporosis?
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-Infection—destruction is greatest at endplates, the posterior elements are relatively spared
-Tumor—irregular vertebral body involvement, pedicles typically are affected, entire vertebra is often infiltrated -Osteoporosis—posterior elements spared, portions of vertebral body retain normal marrow, even in acute compression fractures, anterior wedging |
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How can marrow signal help you distinguish infection vs. tumor vs. osteoporosis?
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-Infection—decreased T1, increased T2, normal diffusion
-Tumor—decreased T1,increased T2, restricted diffusion by “marrow packing” -Osteoporosis—T1/T2 normal unless there’s an acute fracture, diffusion may be increased at the fracture plane |
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How can disk integrity help you distinguish infection vs. tumor vs. osteoporosis?
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-Infection—disk is involved and enhances in pyogenic infections
-Tumor—disks typically spared (prostate cancer is an exception) -Osteoporosis—disks spared |
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How can epidural component (if present) help you distinguish infection vs. tumor vs. osteoporosis?
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-Infection—granulation tissue extends several levels above and below the affected vertebrae (best seen post-gad)
-Tumor—focal mass usually only at level of affected vertebrae. Lymphoma is an exception with more extensive epidural mass -Osteoporosis—rare, unless acute fracture with hematoma or retropulsion of fragments |
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What can be confused with vertebral osteomyelitis?
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Vertebral body sclerosis related to degenerative disk can look like discitis/osteomyelitis on T1, but not on enhanced scans
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What can obscure vertebral body tumors?
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Gadolinium can obscure them by reducing their conspicuity relative to fat
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How can you distinguish acute compression fractures from pathologic fractures?
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-It can be difficult
-Posterior elements are typically spared in benign compression fractures and involved in pathologic -Follow-up scans in 3-6 months can help |
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What usually causes spinal cord abscesses?
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-They’re rare
-Usually the result of direct seeding of the cord from overwhelming sepsis |
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What does a spinal cord abscess look like?
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-Just like a brain abscess
-T2 bright, rim-enhancing, diffusion restricting |
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What do spinal infections look like on plain films?
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-They’re normal until disk or bone destruction occurs
-Earliest sign is erosion of the vertebral endplates -Late in the infection, the endplates may become sclerotic, possibly leading to fusion across the obliterated disk space |
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How long does it take for disc/bone destruction to happen in vertebral infections?
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4-8 weeks
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How do nuclear studies fit in to the workup of spine infections?
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Indium labeled white cell studies and gallium scans are very specific for infection, but they are relatively insensitive for small foci of vertebral osteomyelitis
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How does CT fit into the workup of spine infections?
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It’s useful for paraspinous disease, but it doesn’t show the spinal canal contents very well unless intrathecal contrast is used.
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What sequence can help find epidural abscesses?
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Fat suppression T1 post-gad, they get rid of the normal bright epidural fat.
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What is the most common bacteria in adult spine infections?
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-Staph aureus
-Followed by gram negatives like E. coli, pseudomonas, and klebsiella |
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What should you think about in sickle cell pts?
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Spine infections with salmonella
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What is seen clinically in spine infections?
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-Severe back pain that is unrelieved by any positional maneuvers
-Fevers, chills, leukocytosis, elevated ESR -Blood cultures are often negative, mandating disk biopsy (best obtained before abx) |
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How does S. aureus obliterate the disk space?
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-It produces enzymes that digest the disks
-Destruction of the disk space implies pyogenic infection -TB tends to spare the disk |
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Describe the evolution of findings in pyogenic infection:
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-The osteomyelitis phase: marrow edema with enhancement
-The infection then breaks through to the disk, with intense contrast enhancement -Subligamentous spread to the other side of the disk -Infection can spread along the ALL and PLL extending several levels. -Epidural infection can have a variable appearance ranging from round rim-enhancing areas to more oblong stretches of thickened granulation tissue |
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Why are non-pyogenic infections of the spine confusing?
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-Because they tend to occur in immunocompromised pts—confused with mets in chemo pts, confused for lymphoma in AIDS pts
-They have an indolent course, no leukocytosis -A pathologic fracture with mild epidural mass effect could represent either infection or neoplasm, often biopsy is required |
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How does TB of the spine present?
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-Pott’s disease usually causes slow collapse of one or more vertebral bodies, causing acute kyphotic “gibbus” deformity
-Epidural granulation tissue and bony fragments lead to cord compression -The disks can be preserved -Late stage TB has large paraspinal abscesess |
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What age group gets Pott’s disease?
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Usually under 20
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What does TB meningitis look like?
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Dramatic pachymeningeal enhancement
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What other infection look just TB in the spine?
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Brucellosis
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What fungi typically infect the spine?
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Candida, aspergillus, coccidiodomycosis, blastomycosis
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How do you tell coccidiodomycosis from blastomycosis?
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Cocci, like TB, spares the disks, while blasto can destroy the disks and ribs
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What spinal tumors are rare in children?
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Meningiomas
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What percent of adult spine tumors are meningiomas?
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25%
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What's the best modality to see bony mets to the spine?
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Signal alterations from tumor infiltration within the normally bright marrow fat on T1WIs usually precede any bony changes detectable on plain film or CT, and MR is probably the earliest reliable method (aside from bone marrow biopsy) for detecting the presence of metastatic disease in the spine. Technetium bone scanning, however, remains the most cost-effective tool for whole-body screening.
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Plain film findings in an intramedullary tumor?
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The classic plain film finding of an intramedullary mass—widening of the interpedicular distance caused by slow expansile forces—is seen in fewer than 10% of cases.
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Most common primary intramedullary tumors?
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Astrocytomas and ependymomas are the two most common primary intramedullary tumors, but the distinction between them is difficult to make on imaging grounds alone.
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What do intramedullary astrocytomas and ependymomas look like?
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-Both are expansile, low in signal intensity on T1WIs, and bright on T2WIs, with variable enhancement.
-While some guidelines, based on involvement of the entire cord diameter and longer cord segments (favors astrocytoma) and presence of cysts and hemorrhage (favors ependymoma), have been proposed to distinguish between the two types of tumors, in any single case they are rarely a substitute for biopsy. -Gadolinium contrast is useful to identify the tumor nidus as well as to document spread of tumor along CSF pathways. |
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What do intramedullary hemangioblastomas look like?
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Focal vascular blush at their nidus, with angiographic signs being virtually pathognomonic.
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What non-tumor entities can look like intramedullary tumors?
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-Syrinx
-Abscess |
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Most common primary intramedullary tumor of adults?
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Ependymomas are the most common spinal cord tumor in adults.
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Two types of spinal ependymomas?
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-They can be divided into the cellular (intramedullary) and myxopapillary (filum terminale) types.
-The filum terminale ependymomas are also known as myxopapillary ependymomas on account of their unique histology, and because of their location, a reasonably specific diagnosis can be made on imaging. |
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What cells do spinal ependymomas arise from? Are they benign or malignant?
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-These slow-growing neoplasms arise from ependymal cells lining the central canal of the cord or cell rests along the filum.
-Histologically, these tumors are usually benign, but a complete curative excision may be impossible with the intramedullary types. -Myxopapillary ependymomas often can be excised completely, particularly if they are well encapsulated |
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What do spinal ependymomas look like?
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-Cellular ependymomas present as intramedullarly masses while myxopapillary ependymomas are at the filum terminale.
-Associated hemorrhage can be seen, especially on MR, and cystic areas are common |
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What do spinal astrocytomas look like?
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-Intramedullary masses
-Most (75%) astrocytomas occur in the cervical and upper to midthoracic cord, and presentation in the conus is rarer than with ependymomas. -Fusiform cord widening, hyperintensity on T2WIs, and contrast enhancement often extend over several vertebral body segments -They may be exophytic, and at times may even appear largely extramedullary. |
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How can you tell a spinal hemangioblastoma from a spinal AVM?
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-The nidus shows vascular hypertrophy and may be mistaken for an arteriovenous malformation (AVM).
-However, intramedullary AVMs do not typically show a related cyst or cord expansion |
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Are spinal hemangioblastomas usually intra- or extramedullary?
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-60% are intramedullary
-40% are extramedullary -20% are multiple. |
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What does hydromyelia mean? What does syrngomelia mean?
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Hydromyelia refers to dilation of the central canal of the spinal cord, which is lined by ependyma.
-Syringomyelia, on the other hand, is a cavity outside the central canal that is lined by glial cells. -Distinction between these two conditions is difficult on imaging studies, given that the lining of the cavity cannot be examined histologically. -The generic term covering either—“syringohydromyelia”—is a bit of a tongue twister, and the abbreviated “syrinx” is often used for both conditions. |
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What things cause syrinx?
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-The etiology of a syrinx can be developmental, such as in the Arnold-Chiari malformations.
-However, trauma and tumors, as well as inflammatory and ischemic conditions, can also lead to a syrinx. -Always suspect tumor as a cause of unexplained syrinx. -Unless definite benign etiology is apparent, such as prior history of cord contusion or the low cerebellar tonsils of a Chiari I malformation, give gadolinium to search for a tumor nidus. |
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What MRI artifact can mimic a syrinx?
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Be aware that high signal truncation (Gibbs) artifacts can superimpose themselves over the cord, mimicking a syrinx.
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What does a syrinx look like? What entity can mimic a syrinx?
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A syrinx cavity should have very well-defined margins, and its contents should follow CSF signal intensity.
If the syrinx borders are indistinct and the signal is brighter than CSF on T1WIs and darker than CSF on T2WIs, you may be dealing with severe central cord edema. |
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What does a syrinx look like on CT myelography?
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With CT myelography, contrast often enters into a syrinx cavity with delayed images. Occasionally, this technique is useful in establishing the degree to which a cord cavity communicates with the CSF.
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What should you think of if you see multiple meningiomas?
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Neurofibromatosis
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What space are spinal meningiomas typically contained in?
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The usual location is extramedullary/intradural, although there can be an extradural component.
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What do spinal meningiomas look like?
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-Dense calcification can occur, as in the brain
-CT and MR characteristics are similar to that of intracranial meningiomas, with dense homogenous enhancement and broad dural tails. |
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What could you confuse a spinal meningioma with?
How do you tell the difference? |
-A schwannoma
-A schwannoma often will extend out through a neural foramen, and lacks a broad dural base. -Schwannomas are less well vascularized than meningiomas and may undergo cystic necrosis. |
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Where do spinal schwannomas originate?
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Schwannomas usually originate from the dorsal sensory nerve roots, but they remain encapsulated and extrinsic to the nerve, causing symptoms by mass effect.
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What do spinal neurofibromas look like?
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-Extension into the neural foramen is a frequent finding, especially in the cervical and thoracic regions.
-Part of the tumor will be intraspinal, and part will be extraspinal, with the waist at the often-expanded neural foramen, giving the classic “dumbbell” appearance. -In the lumbar region, schwannomas tend to remain within the dural sac -Unlike schwannomas, neurofibromas rarely show cystic degeneration or internal hemorrhage. -Spinal neurofibromas can have a plexiform configuration, extending out through multiple adjacent neural foramina -Intradural or extradural in location both schwannomas and neurofibromas enhance. -Heterogeneous enhancement with areas of low signal is more characteristic of a neurofibroma. -In patients with NF-1, look for the additional imaging findings of kyphoscoliosis, rib dysplasia (ribbon ribs), and scalloping of the posterior vertebral body caused by dural ectasia |
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Manifestations of NF-1 in the spine?
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-Spinal neurofibromas
-kyphoscoliosis, rib dysplasia (ribbon ribs), and scalloping of the posterior vertebral body caused by dural ectasia |
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Define "drop metastasis":
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-Tumor cells in the posterior fossa exfoliate into the CSF and “drop” down into the spinal canal, implant on the pia, and grow into small nodules, giving rise to the term “drop metastases”.
-The classic cause of spinal intradural/extramedullary metastases is subarachnoid seeding of primary CNS tumors, such as posterior fossa medulloblastomas, ependymomas, and pineal region neoplasms. -However, any tumor spreading via the CSF pathways of the brain can involve the spinal leptomeninges. |
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Which non-CNS malignancies like to metastasize to the leptomeninges?
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-Solid tumors, such as breast and lung carcinoma, can metastasize to the subarachnoid space.
-Leukemia probably has the highest rate of infiltration of the meninges of any non-CNS tumor. -Systemic lymphoma (particularly T-cell lymphomas) and carcinomas can also spread to the CSF pathways. |
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How do leptomeningeal metastases present?
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Leptomeningeal metastases can cause considerable inflammation, and patients can present with signs of meningeal irritation, leading to the term “carcinomatous meningitis.”
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What do leptomeningeal metastases look like on myelograms?
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Leptomeningeal metastases classically appear as multiple intradural nodules, causing filling defects on myelography or CT myelograms.
-Sometimes thin, smooth sheets of intrathecal tumor cells, described by pathologists as “sugar coating” of the cord and roots, will be difficult to detect on myelograms because there is no discrete mass. |
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Differential for thickened leptomeninges?
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The differential diagnosis of thickened leptomeninges (pachymeningitis) includes carcinomatous and infectious meningitis, postinfectious states such as Guillain-Barré syndrome, and inflammatory arachnoiditis in the postoperative patient. In the immunocompromised patient, diffuse leptomeningeal enhancement requires CSF analysis to distinguish between tumor and infection.
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Why are post-operative spine MRI's confusing?
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-Blood in the subarachnoid space may be bright on T1WIs, and in the immediate postoperative period it is essential to obtain pre–gadolinium injection images to ensure that trace methemoglobin is not mistaken for enhancing drop metastases.
-Subarachnoid and subdural blood in the spinal canal can cause leptomeningeal irritation and enhancement, further confusing the postoperative “rule out drop metastasis” scan. -These problems are easily avoided by obtaining a preoperative enhanced MR scan of the spine in any patient at risk for spinal drop metastases, such as a child with medulloblastoma. |
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Differential for extradural mass?
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-Neoplasm is the second most common cause of extradural mass, after disk herniations and other degenerative processes; however, in immunosuppressed patients and in certain parts of the world, infections may outnumber neoplasms as a source of extradural mass effect.
-Primary vertebral tumors such as chordomas, giant cell tumors, hemangiomas, and sarcomas behave like any other extradural mass in terms of myelographic findings and must be kept in the differential diagnosis. -The most common extradural neoplasm, however, is metastatic spread of solid tumors, such as breast, lung, and prostate carcinoma. |
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How do metastatic lesions get into the vertebral bodies?
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-Most metastases, like infection, reach the vertebrae via arterial seeding, although prostate carcinoma may preferentially ascend to the lumbar region via the Batson venous plexus.
-The vertebral marrow space, like the liver and the lungs, “filters” a great deal of blood and is a fertile ground for metastatic deposits. |
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What do mets in the vertebral bodies look like?
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-As these deposits grow, they replace normal marrow, which contains considerable fat and is bright on T1WIs.
-Metastases therefore appear as low signal areas on T1WIs or high signal areas on T2WIs, because of their higher water content versus fat. -Prostate cancer and other densely sclerotic metastases can be somewhat confusing on MR, unless one appreciates that areas of intensely sclerotic bone may be dark on all sequences. -As with other metastases, neovascularity develops to supply the expanding mass of intravertebral tumor cells, which is why vertebral metastases can enhance intensely, although this may reduce their conspicuity against background fat, unless fat saturation is used. |
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Two ways mets to the vertebrae can cause cord compromise?
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-Once tumor has infiltrated the cortex, spread to the epidural space can occur
-compression fractures may lead to cord compromise. |
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What types of paraspinous tumors like to invade the spine?
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Retroperitoneal and mediastinal tumors can invade the vertebral column and spinal canal by direct extension.
Tumors that arise from primitive paraspinous neural remnants that are similar to fetal neuroblasts: -Neuroblastoma -Ganglioneuroma -Ganglioneuroblastoma These tumors frequently involve the spinal canal, infiltrating through the neural foramina. Any paraspinous tumor can do likewise, including: -Lymphomas -Apical lung (Pancoast) tumors -A variety of retroperitoneal and mediastinal carcinomas and sarcomas |
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What do leukemic infiltrates in the spine look like?
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-Leukemias change the appearance of the vertebrae in the characteristic fashion of diffuse, even replacement of the marrow with tumor
- Solid leukemic infiltrates, or chloromas, can involve the epidural space and cause cord compression. |
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What is a chloroma?
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A solid leukemic infiltrate that can involve the epidural space and cause cord compression
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What does multiple myeloma involvement of the spine look like on MR?
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-Multiple myeloma can present as a diffuse and homogeneous low signal in the spine on T1WIs but more typically shows multiple focal defects.
-Solitary plasmacytomas are in the differential diagnosis for vertebral plana (totally collapsed vertebral body), along with eosinophilic granuloma, leukemia and severe osteoporosis |
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Differential for vertebral plana?
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-Solitary plasmacytomas
-Eosinophilic granuloma -Leukemia -Severe osteoporosis |
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What does myelofibrosis look like on MR?
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Myelofibrosis will present as very dark marrow space on T1WIs and remains dark on T2WIs since there is “dry” fibrous tissue rather than “wet” tumor replacing the marrow
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How does extramedullary hematopoeisis affect the spine?
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Patients with hemoglobinopathies, such as sickle cell disease, may have areas of extramedullary hematopoiesis, which are often paraspinous, and can infiltrate into the spinal canal, causing cord compression.
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Are spinal lesions of lymphoma usually primary or secondary?
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Non-Hodgkin and B-cell types predominate in the CNS. More than 30% of systemic lymphomas have skeletal manifestations, and spinal involvement is usually secondary rather than primary.
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What does lymphoma involvement of the spine look like?
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-Tumor masses may be intraspinal, paraspinal, or both (extradural > intradural > intramedullary).
-Cord compression is a common presenting symptom. -The epidural and paraspinous masses are usually more extensive than metastatic disease from solid tumors and can mimic the appearance of epidural infection. -Lymphomas involving the mediastinum and retroperitoneum can insidiously invade the spinal canal via the neural foramina. -Given that CT remains the dominant technique for following lymphoma in the chest and abdomen, subtle intraspinous extension can easily be missed, and any lymphoma patient with back pain should be evaluated by MR |
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What causes spinal infarcts?
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Spinal “strokes” are quite rare in comparison with cerebrovascular accidents. The classic scenario is a patient who becomes paralyzed after major thoracic surgery, such as repair of a thoracic aortic aneurysm.
Obviously, when a patient in the recovery room after aortic surgery is paraplegic, it does not require great insight to consider a cord infarct. More subtle, however, are cases where atherosclerotic disease or severe degenerative disease leads to thromboembolic cord infarctions, and infarcts must be considered in the differential of unexplained myelopathy. Spinal stroke can also be related to spinal AVMs. |
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What does a spinal infarct look like on MR?
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The affected segments of the cord will appear bright on T2WIs and DWIs, with enhancement, similar to a brain infarct, followed by the development of myelomalacia. The spinal gray matter in an infarct will enhance to a greater degree than the white matter, as is the case in the brain
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Describe intramedullary spinal AVMs:
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Intramedullary AVMs have a congenital “nidus” of abnormal vessels within the cord substance that causes symptoms by hemorrhage or ischemia because of steal phenomenon. These typically present in young patients with hemorrhage, leading to acute paraparesis. Some are high flow, with visible signal voids within the cord substance. Others escape detection even with angiography and are similar to cavernous vascular malformations in the brain. MR is the primary means for their identification
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What's the major difference between intramedullary and extramedullary spinal vascular malformations?
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-Intramedullary AVMs usually connect an aberrant artery with a vein through a series of capillaries
-Extramedullary spinal AVMs are typically an arteriovenous fistula—a direct connection between an artery and vein without an intervening nidus of congenitally abnormal vasculature |
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How do spinal dural arteriovenous fistulas (SDAVFs) cause symptoms?
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The direct arterial inflow into the local venous system through the fistula, undamped by the resistance of a capillary bed, raises pressure within the coronal venous plexus draining the spinal cord, which is valveless (Fig. 10.51). Spinal dural arteriovenous fistulas (SDAVFs) cause symptoms through venous hypertension and congestion of the cord with edema.
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What do spinal arteriovenous fistulas look like?
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-Cord edema can be detected on MR as increased signal on T2WIs, typically within an enlarged conus, which often enhances.
-The reason for cord enhancement in SDAVFs is not fully understood, but it probably results from breakdown of the blood-brain barrier because of either chronic infarction or some sort of capillary leak phenomenon secondary to venous hypertension. -Regardless of the explanation, enhancement of the cord with SDAVFs is yet another reason why a postcontrast scan should be obtained in any patient with unexplained myelopathy. |
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What exam can you get if you think there might be a spinal dural arteriovenous fistula but you don't want to do angiography?
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-In the face of an equivocal MR, an alternate examination, short of spinal angiography, has been supine thoracic high-dose plain film myelography.
-The dilated veins of the coronal venous plexus appear as serpentine filling defects in the dorsal subarachnoid space on myelography. -An additional advantage of myelography is the potential to identify the primary arterialized vein fed by the fistula, a landmark that can greatly facilitate the angiographer's search for the arterial supply to fistula -Nowadays, focused MR angiography is increasingly successful in depicting dilated spinal veins and even predicting the level of the fistula, reducing the iodinated contrast load needed in subsequent catheter angiography. |
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What MR sequences are particularly important in evaluating the pediatric spine?
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T1WIs are preferred for evaluating fine anatomic detail as well as the fat components that are seen in many of these disorders. The standard pediatric spine examination for congenital anomalies, therefore, includes T1W sagittal and axial images; T2WIs are less critical. If there is a “sacral dimple” or other skin defect, tape a marker (such as a vitamin E capsule) over it to insure that the defect is identifiable on the scan.
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Where does the conus terminate in a newborn?
(know this before you go calling a tethered cord!) |
The conus in a newborn is normally at L2 and typically ascends by one to two vertebral segments as the child grows.
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What does a tethered cord look like?
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-When the cord is truly tethered, the conus will be low in position (below L2), particularly as growth occurs.
-Tethered by a thickened filum terminale (>2mm) +/- fibrolipoma -The fibrolipoma is often continuous with subcutaneous fat through dorsal dysraphism -It can be difficult to determine the exact position of the conus, as the roots of the cauda equina, when tethered, form a taut mass in the posterior lumbar canal, obscuring the conus/cauda junction. -Associated with scoliosis |
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What should you think if you see a tethered cord?
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Look for a Chiari!
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What should you think of if you see a fatty lesion around the conus?
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-Tethered cord!
-BUT not every lumbar intradural fatty deposit implies pathologic tethering, and small fibrolipomas of the filum terminale may be noted on MR examinations in patients with normal conus position and no symptoms of cord tethering. A cohort of these patients needs to be followed throughout their lives before such fibrolipomas can be dismissed as incidental, since symptoms of cord tethering occasionally can present well into adulthood. |
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Where are intramedullary lipomas found usually? Who gets them and how do they present?
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These are usually thoracic, more common in males, and, when symptomatic, present with myelopathy in young adulthood
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Differential for a fat containing intramedullary lesion?
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-Lipoma
-Teratoma (look for cysts, hemorrhage, debris) -Dermoid (associated with dorsal dermal sinus) |
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How do you tell an epidermoid apart from an arachnoid cyst?
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Epidermoids restrict diffusion
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What is an implantation epidermoid?
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“Implantation epidermoid” can occur as rare complication of lumbar puncture, which is why the needle bevel must be kept in place during a lumbar puncture.
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What is a solid leukemic infiltrate called?
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Chloroma
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What is caudal regression syndrome? What causes it? What is it associated wtih?
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-The distal spine and sacrum may be hypoplastic or absent and the conus has a blunted appearance
-Caudal regression is believed to be caused by an insult to the mesoderm during the fourth gestational week, and associated cardiac and renal anomalies are common. -There is a high association with maternal diabetes. |
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What's the difference between an anterior meningocele and a posterior meningocele?
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-A posterior meningocele is caused by neural tube defect
-An anterior meningocele is caused by a leptomeningeal diverticulum, and they can be huge |
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What does a spinal arachnoid cyst look like? What's the primary differential?
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-Arachnoid cysts in the spine present as extramedullary masses that are relatively isointense to CSF.
-As in the brain, the primary differential diagnostic consideration is an epidermoid (restricts diffusion) |
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Where do spinal contusions occur?
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In the spine, contusions usually occur at sites of fractures, secondary to bony impingement and cord compression. However, spinal cord contusions may occur in the absence of spinal fractures following hyperflexion or hyperextension, resulting in myelopathy.
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Which ligaments must be strutinized for edema?
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The anterior and posterior spinal ligaments must be examined carefully for edema, representing either partial or complete tears, with risk of future instability.
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Explain the difference between subdural and epidural spinal hematomas and their causes:
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-“extramedullary” hematomas can follow trauma, with certain important distinctions.
-Subdural hematomas are rare in the spine (and usually related to coagulopathies, while epidural hematomas are far more common. |
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Explain why most intracranial hematomas are subdural and why most spinal hematomas are epidural:
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-The majority of posttraumatic bleeding is venous.
-In the bony calvaria, the dura is functionally the periosteum, with no potential space between the dura and bone for low-pressure venous blood to accumulate. -It takes bleeding under arterial pressure to create an epidural hematoma by stripping the dura away from the inner table. -In the spine, the dura is separated from the bone by epidural fat. -In the ventral spinal canal, the epidural space also contains a rich plexus of veins that drains the vertebral bodies. |
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Explain how a patient could develop worsening myelopathy in the setting of normal CT/plain films.
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-In the ventral spinal canal, the epidural space contains a rich plexus of veins that drains the vertebral bodies.
-Trauma, with or without vertebral fracture, can tear these veins, resulting in an epidural hematoma. -These hematomas grow with time, leading to cord compression in the setting of normal plain films. |
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What do extramedullary hematomas look like on CT?
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CT may detect these epidural hematomas in the lumbar spine, where there is some fat to provide contrast, but generally will not demonstrate an epidural hematoma in the cervical or thoracic spine unless intrathecal contrast is given.
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Where do spinal nerve root avulsions typically occur?
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In the spinal canal, the most common site for root avulsion is the cervical spine, probably because of its wide range of motion during accidents. The roots serving the brachial plexus and upper extremities are typically affected, with obvious neurologic deficits.
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What does a nerve root avulsion look like?
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Typically, CSF will leak out into the epidural space through the rent in the arachnoid and dura from the missing nerve
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Where do most spinal cord avulsions occur?
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The junction of the cervical and thoracic cord is a weak point where tearing can occur in injuries that stretch the cord
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