Chapter 9 - Spine Imaging Flashcards
This results from compromise of the spinal cord itself, due to mechanical compression, intrinsic lesions, or inflammatory processes grouped under the term “myelitis”.
Myelopathy
Classic symptoms include bladder and bowel incontinence, spasticity, weakness, and ataxia.
With cord compression, a clear motor or sensory spinal cord “level” may develop.
Myelopathy
This is due to impingement or irritation of the spinal nerves within the spinal canal, lateral recess, neural foramen, or along the extraforaminal course of the nerve.
Radiculopathy
Most common causes of radiculopathy
- Disc herniations
- Spinal stenosis
- Uncovertebral joint spurring
This was once the initial test in every spine evaluation, but this is no longer logical or cost effective.
It continue to be useful for ruling out trauma to the vertebral column and other acute screening settings.
Conventional radiography.
This is almost always done in conjuction with CT.
Indications include complex postoperative cases and patients in who MR is contraindicated due to incompatible implanted devices.
Myelography
Contrast agents that are absolutely contraindicated for myelography, as they result in severe inflammation, seizures, arachnoiditis and even death.
Ionic contrast agents
Recommended dosage of nonionic contrast in adults depends on the region to be studied, the size of the patiet, and the size of thecal sac.
What is the convenient and conservative rule of thumb in adults?
Not to exceed 3 g of intrathecal iodine.
17 ml of 180 mg/mL
12.5 mL of 240 mg/mL
or
10 mL of 300 mg/mL
The three standard concentrations.
This has been replaced by MR for most screening examinations of the spine, except for acute trauma.
Computed Tomography
This is the most common spinal cord “inflammatory” disorder, and by far the most frequent cause of intramedullary lesion seen on MR.
Multiple sclerosis (MS)
Best screening protocol of MS
Sagittal T2W or inversion recovery sequences -
Where MS plaques appear as areas of increased signal intensity.
Location of MS plaques in the spinal cord
Since the white matter is on the outside of the cord.
MS plaues tend to be PERIPHERAL.
This is an autoimmune disorder affecting the spinal cord and optic nerves.
The spinal cord lesions are longer than MS, and the brain is often spared.
Devic disease, or neuromyelitis optica (NMO)
A CNS inflammatory process in which a necrotizing arteririts leads to cord ischemia and injury.
Antibodies damages neuronal elements directly.
Systemic lupus erythematosus (SLE)
Imaging finding of SLE of the spinal cord.
The spinal cord will show diffuse areas of increased signal intensity with cord swelling on T2WI.
SLE “lesions” have less well-defined margins than the discrete plaques of MS and may involve the cord over 4 to 5 vertebral body segments.
How does rheumatoid arthritis cause spinal cord injury?
Focal inflammatory change termed “pannus” destroys the transverse ligament of C1, allowing the odontoid slide posterioly relative to C1.
This leads to cord compression, particulary in flexion.
This shows the classic “bamboo spine”, due to extensive bridging of syndesmophytes across multiple vertebral bodies.
Ankylosing spondylitis
Without the flexibility of the disc spaces, the rigid AS spine is prone to fracture (arrow) with even mild trauma.
Patients typically have sudden high fevers, followed within 4 weeks by rapind onset of motor, sensory, and usually autonomic dysfunction, sometimes referable to a specific spinal cord level.
Acute viral myelitis
Imaging pattern of acute viral myelitis
The imaging findings typically are a focal area of cord swelling with high signal on T2WI, with variable enhancement.
This is a progressive ascending motor weakness that affects more than one limb, but involves peripheral nerves rather than the spinal cord.
Guillain-Barre syndrome
Another name of Gullain-Barre syndrome
Acute inflammatory polyradiculoneuropathy
This presents as a diffuse leptomeningeal granulomatous nodules, which typically enhance.
Neurosarcoidosis
Appearance is similar to carcinomatous and mycobacterial meningitis, and the distinction must be made on clinical grounds.
What are the common causes of arachnoiditis?
Iatrogenic - including inflammation after spine surgery, spinal anesthesia, or spine “injection” procedures such as epidural nerve blocks.
In arachnoiditis, the normally free-layering lumbar roots become adherent to each other, or to the peripheral wall of the thecal sac, giving the sac what appearance?
Give the sac a “bald” appearance
This occurs roughly 6 to 12 months after initial radiation treatment, with affected areas demonstrating increased signal intensity on T2WI with variable enhancement.
Radiation myelitis
This is the most common causes of spine infection in adults.
Staphylococcus aureus
followed by gram-negative bacteria, particularly Escherichia coli, Pseudomonas, and Klebsiellla.
These are rare, and usually resukt of direct seeding of the cord from overwhelming sepsis.
Spinal cord abscesses
- Appear similar to those in the brain:
Bright centrally with a dark rim on T2WI with rim enhancement.
Most common neoplasm involving the adult spine.
Vertebral metastases
The most common spinal cord tumor in adults.
Ependymomas
Ependymoma can be divided into two types.
- Cellular (intramedullary)
2. Myxopapillary (filum terminale)
Most astrocytomas occur in what region of the spinal cord?
Cervical and upper midthoracic cord.
- Presentation in the conus is rare than with ependymomas.
Imaging pattern of spinal astrocytoma
- Fusiform widening
- Hyperintense on T2WI
- Contrast enhancement
often extend over several vertebral body segments.
It is the most common spinal cord tumor in children.
Astrocytoma
It has high association with von Hippel-Lindau syndrome.
These rare tumors, with their chracteristc densely enhancing nidus, represent 2% of intraspinal neoplasms.
Hemangioblastoma
40% are extramedullary and 20% are multiple.
The nidus shows vascular hypertrophy and may be mistaken for an AVM.
This refers to dilatation of the central canal of the spinal cord, which is lined by ependyma.
Hydromyelia
This is a cavity outside the central canal lined by glial cells.
Syringomyelia.
This is the most common intradural tumor in the thoracic region and represents roughtly 25% of all adult intraspinal tumors.
Meningioma
Main differential consideration for spinal meningioma.
Schwannoma
- often will extend out through a neural foramen and lacks a broad dural base.
Schwannoma originate from where?
Dorsal sensory nerve roots
- but remain extrinsic to the nerve, causing symptoms by mass effect
Frequent finding of Schwannoma
Extension to the neural foramen - especially in the cervical and thoracic regions.
Classic “dumbbell” appearance
Schowannoma
- Part of the tumor will be intraspinal, and part will be extraspinal, with the waist at the often-expanded bony neural foramen.
What is the classic cause of spinal intradural-extramedullary metastases?
Subarachnoid seeding of primary neoplasm,
- typically medulloblastoma, ependymomas, and germ cell tumors
Differential diagnosis of thickened leptomeninges
- Carcinomatous and infectious meningitis
- Posinfectious states such as Guillain- Bree
- Granulomatous diseases
- Inflammatory arachnoiditis in post operative patient.
Second most common cause of extradural mass.
Neoplasm
- after disc herniations and other degenerative processes.
Most common extradural neoplasm
Metastases of solid tumors
- such as breast, lung, and prostate carcinoma.
Process of metastases
via arterial seeding
- prostate carcinoma may preferentially ascend to the lumbar region via Batson venous plexus.
Tumors that can involved the spinal canal by infiltrating through neural froamina.
Round cell tumors such as lymphoma in adults and neuroblastoma in children
Differential diagnosis for vertebral plana (totally collpased vertebral body)?
- Solitary plasmacytomas
- Eosinophilic granuloma
- Leukemia
- Severe osteoprosis
Patient who becomes paralyzed after major thoracic surgery, such as repair of thoracic aortic aneurysm, is a classic scenario of what disease?
Spinal cord infarction
Another iatrogenic cause of spinal stroke is spinal epidural steroid injections that inadvertently enter the vasculature supplying the spinal cord.
These have a congenital “nidus” of abnormal vessels within the cord substance, which cause symptoms by hemorrhage or ischemia because of steal phenomenon.
Intramedullary AVMs
This has a direct connection between an artery and vein without an intervening nidus of congenitally abnormal vasculature.
Extramedullary AVM -
Spinal dural arteriovenous fistula (SDAVF)
The most common site for root avulsion
Cervical spine
- probably because of its wide range of motion during accidents.
Symptoms of Erb palsy
- Shoulder adducted and internally rotated
- Elbow extended and pronated
- Wrist flexed
What nerves are injured in Erb palsy?
C5, C6, and C7
This is defined as a localized or focal displacement of disc material involving less than 25% (90 degreess) of the periphery of the disc, as viewed in the axial plane.
Disc herniation
This involves greater than 25% of the circumference of the disc, and may result from disc degeneration, ligamentous laxity, or bony remodeling.
Disc bulge
- It is not a disc herniation
Mild disc bulging at L5-S1 <2 mm is considered normal variant.
It is defined as displaced disc material extending beyond less than 25% of the disc space, with the greatest measure in any plane being less than the measure of the base
Disc protrusion
A protrusion has a broad base at its origin, and does not extend above or below the level of the disc in the sagittal plane
It is defined as a herniation where the greatest measure of the herniated material is greater than the base at the site of origin.
Disc extrusion
The presence of an extrusion, by definition, implies that there is an annular disruption.
This is encroachment of the bony or soft tissue structures of the spine on one or more of the neural elements, with resulting symptoms.
Spinal stenosis
Most common cause of central canal stenosis
Degenerative disease
of the facets, with bony arthritis that encroaches on the central canal.
- Degenerative joint disease (DJD)
Most common cause of neuroforaminal stenosis
Degenerative joint disease
Bony canals in which the nerve roots lie after they leave the thecal sac and before they enter the neural foramen.
Lateral recesses
Defects in the bony pars interarticularis
Spondylolysis
Modic type
- Hypointense on T1
- Hyperintense on T2
It represents inflammatory response to degenerative disc disease, but can also be a sign of infection.
Modc Type I
Modic type
- Hyperintense on T1
- Hypointense on T2
Most common appearance
These represent fatty marrow conversion of the previously inflamed bone.
Modic Type II
Modic type
- Hypointense on T1
- Hypointense on T2
Modic Type III
Represent end-stage bony sclerosis, which can also be seen on plain films.
