neuroradiology Flashcards
Disk protrusion terminology
Bulge: Broad-based disk bulge. Usually bulging annulus fibrosus. Protrusion: Focal disk bulge. Usually herniated nucleus pulposus.
Intervertebral disk high intensity zone (HIZ)
High T2 signal of annulus indicating annular tear.
Disk free fragment mimickers
Conjoined root: Normal variant of two roots exiting thecal sac together. Same density of thecal sac. Tarlov cyst: Normal variant of dilated nerve root sleeve. Same density of thecal sac.
Lateral Disks
May cause nerve root impingement causing symptoms of a superior level. Nerve root has already exited central canal.
Common causes of Central Canal Stenosis
Facet joint degenerative change (most common). Lligamentum flavum hypertrophy.
Most common cause of neuroforaminal stenosis
Facet joint degenerative change with bony encroachment.
Lateral recess
Lumbar spine bony canals where nerve roots lie after exiting thecal sac and before entering neuroforamen. Hypertrophy of superior articular facet is most common cause of encroachment.
Spondylolysis identified on axial images
Break in bony ring of the lamina (pars interarticularis) at the mid vertebral body level.
Spondylolisthesis occurs from either
Bilateral spondylolysis. Facet joint degenerative change.
Distinguishes postop scar from disk material
Scar tissue enhances. Disk material has only minimal peripheral enhancement.
Differentiates disk infection fromdegenerative disk disease at MR
Type 2 degenerative disk disease: Low T1 disk and high T2 parallel endplate bands. Disk space infection: High T2 disk.
Myelopathy neurologic signs
Ataxia. Bowel and bladder incontinence. Babinski sign.
Radiculopathy neurologic signs
Muscle weakness. Decreased reflexes. Dermatomal sensory deficits.
Urgency for imaging acute myelopathy
Poor prognosis if left untreated for greater than 24 hours.
Common causes of myelopathy
Extramedullary: Epidural mass cord compression. Cervical spine stenosis. Intramedullary: Tumor. Inflammation, Arteriovenous malformation (AVM). Spinal dural arteriovenous fistula (SPAVF).
Definition of Intramedullary spinal canal lesion
Usually confined to spinal cord. May be exophytic.
Definition of extramedullary spinal canal lesion
Outside of spinal cord. May be intradural or extradural.
Intradural intramedullary lesions
Ependymoma. Astrocytoma. Hemangioblastoma. Lipoma/(Epi)dermoid. Syringohydromyelia. Intramedullary AVM. Met/abscess (rare).
Intradural extramedullary lesions (includes subarachnoid space)
Meningioma. Schwannoma/neurinoma. Neurofibroma. Hemangiopericytoma. Lipoma/(Epi)dermoid. Arachnoid cyst/adhesion. Drop/leptomeningeal metastasis. Veins (extramedullary AVM).
Extradural extramedullary lesions
Degenerative: Herniated disc. Synovial cyst. Osteophyte. Rheumatoid pannus. Nondegenerative: Metastasis. Abscess. Hematoma. Primary tumor expansion or invasion. Epidural lipomatosis
