Ebook Neuroradiology companion - Methods, guidelines, and imaging fundamentals (5/E): Part 2

(BQ) Part 2 book “Neuroradiology companion - Methods, guidelines, and imaging fundamentals” has contents: Brachial plexus, congenital malformations, degenerative spine, infection inflammation, vascular disorders, neck masses, temporal bone,… and other contents.

SECTION B SPINAL IMAGING

CHAPTER 20

Brachial Plexus

Inflammatory and Infectious Plexitis

Key Facts

Viral and idiopathic plexitis:

These are predominantly sensory and have an insidious onset

Most patients are between 30 and 70 years of age (uncommon in thevery young)

Most resolve spontaneously in 8 to 12 weeks after their onset

Other causes include: drug reaction (allergic), post viral(autoimmune), due to a vasculitis and a heredofamilial type

Main differential diagnosis: perineural tumor spread, post radiationchanges, stretching injury, hypertrophic polyneuropathy, lymphoma,chronic inflammatory demyelinating polyneuropathy, thoracic outletsyndrome

Radiation-induced plexitis:

Generally occurs with doses >6,000 cGy

In the acute type, symptoms tend to be permanent (probably due tovascular injury and nerve ischemia)

In the subacute type (onset generally at about 6 months aftertreatment), symptoms are transient and usually reversible

Most radiation-induced plexopathies are predominantly sensory

Diffuse thickening and enhancement of the brachial plexus may be

progression, viral plexitis and chronic inflammatory demyelinatingpolyneuropathy may have a similar appearance.

FIGURE 20-1 Coronal fat suppressed T2 shows thickening and increased

signal in the roots and trunks of the left brachial plexus due to a herpeszoster infection

FIGURE 20-2 Coronal fat suppressed T2, in a different patient, show

diffuse thickening of the right plexus The cause was never found butsymptoms resolved with only supportive treatment

FIGURE 20-3 Coronal fat suppressed T2 in a different patient with

diffuse (presumably drug-induced) plexopathy shows diffuse thickeningand increased signal in the brachial plexus bilaterally

FIGURE 20-4 Coronal post contrast T1 shows increased signal intensity

from the left infraclavicular brachial plexus (arrow) in a patient post

ipsilateral mastectomy and radiation therapy

FIGURE 20-5 Corresponding coronal fat suppressed T2 shows increased

signal (arrow) in the abnormal brachial plexus.

SUGGESTED READINGS

Chhabra A, Thawait GK, Soldatos T, et al High-resolution 3T MR neurography

of the brachial plexus and its branches, with emphasis on 3D imaging AJNR

Am J Neuroradiol 2013;34:486–497.

Tharin BD, Kini JA, York GE, et al Brachial plexopathy: a review of traumatic

and nontraumatic causes AJR Am J Roentgenol 2014;202:W67–W75.

Traumatic Brachial Plexus Injuries

Vascular injuries:

Injuries to the subclavian artery may result in pseudoaneurysms and acompressive mixed sensory/motor neuropathy The brachial plexusmay also be damaged during placement of subclavian catheters

Hematomas are generally post traumatic and most are not associatedwith significant vascular injuries

While well-encapsulated hematomas that result in a plexopathy may

be surgically drained, most are diffuse and not amenable to drainage(in such patients the plexopathy is generally due to traction injuries orpost-traumatic thoracic outlet syndrome)

Avulsion and stretch injuries:

Cervical nerve root avulsions are generally caused by traction injuries

of the upper extremities (in the lower spine, they are related to spinal

Stretching of the brachial plexus may sometimes lead to neuromaformation

FIGURE 20-6 Coronal non contrast T1 shows large rounded and

“laminated” appearance of a right subclavian artery pseudoaneurysm

FIGURE 20-7 Sagittal T1, in the same patient, clearly shows the

concentric layers of varying signal intensities that are typical of giantaneurysms The plexus is compressed and not identifiable

FIGURE 20-8 Coronal T2, in a different patient, shows a fluid-filled

pseudomeningocele (arrow) from avulsion of the left C7 nerve root.

FIGURE 20-9 Axial T2, in a different patient, shows dark blood-filled

pseudomeningocele (arrow) with inward displacement of thecal sac and

subarachnoid blood

FIGURE 20-10 Coronal T2 in a different patient shows thickening and

increased signal throughout the right brachial plexus (arrows) due to

stretching injury

FIGURE 20-11 Coronal T1, in a different patient with poorly healed

clavicle fracture, shows large callus (arrow) which resulted in a

compressive plexopathy

SUGGESTED READINGS

Castillo M Imaging the anatomy of the brachial plexus: review and

self-assessment module AJR Am J Roentgenol 2005;185:S196–S204.

Yoshikawa T, Hayashi N, Yamamoto S, et al Brachial plexus injury: clinical manifestations, conventional imaging findings, and the latest imaging

techniques Radiographics 2006;26(suppl 1):S133–S143.

Key Facts

Fatty tumors:

Brachial plexus lipomas are not uncommon and are generallyasymptomatic but may result in a compressive plexopathy when verylarge Liposarcomas are rare

Lipomas do not enhance and are nearly homogeneous (but may haveinner strands) Liposarcomas show inhomogeneous contrastenhancement and have an aggressive appearance Invasion of theplexus may render the patient inoperable

Metastases:

Most brachial plexus metastases are due to carcinomas of the breastand lung and lymphoma They may present as a focal mass orinfiltrate the plexus diffusely

Pancoast tumors:

Arise at the apical pleuropulmonary groove and are most commonlysquamous, adeno- or large cell carcinomas of the lung Prognosis ispoor when the brachial plexus is involved (stage T4)

In 25% of patients the tumor will extend to the roots of the brachialplexus and even intraspinally resulting in cord compression

Nerve sheath tumors:

Schwannomas are the most common primary tumor of the brachialplexus and more commonly occur in the roots and trunks Extensioninto and expansion of the corresponding neural foramen is typical.Enhancement pattern is non-specific

Neurofibromas are the hallmark of NF-1 and may occasionally besporadic They may attain a large size, involve the entire plexus, andmay be bilateral Enhancement is variable but a significant change insize and enhancement may indicate malignant degeneration

FIGURE 20-12 Corresponding fat suppressed post contrast image shows

peripheral and nodular enhancement in a liposarcoma Note that the

brachial plexus (arrow) enhances suggesting invasion.

FIGURE 20-13 Parasagittal T1, in a different patient, shows well-defined

fatty benign lipoma (arrow).

FIGURE 20-14 Coronal fat suppressed T2, in a different patient, shows

massive thickening of the right plexus (arrow) due to breast cancer

infiltration

FIGURE 20-15 Coronal non contrast T1 shows normal right interscalene

fat triangle (arrow) On the left side, a large Pancoast tumor has invaded

and obliterated this fat which is where the brachial plexus is located

FIGURE 20-16 Coronal T2 shows a schwannoma with cystic changes in

the region of the right roots/trunks extending to a neural foramen (arrow).

FIGURE 20-17 Coronal fat suppressed T2 shows very large

neurofibromas in the right plexus and subtle involvement of the leftplexus

SUGGESTED READING

Lutz AM, Gold G, Beaulieu C MR imaging of the brachial plexus Neuroimaging

Clin N Am 2014;24:91–108.

Sixteen percent of patients with this anomaly are the offspring ofdiabetic mothers.

Most patients with caudal regression anomalies have a neurogenicbladder, motor weakness, and feet deformities

Types:

Type 1: The sacrum is completely or partially absent, and thedistal conus (wedge shaped) and cauda equina are notcompletely formed and terminate at a high level

Type 2: Less severe form where the spinal cord is dysplastic and

FIGURE 21-1 Lateral view radiograph shows a dysplastic S1 vertebra

and absence of the sacrum below this level (arrow).

FIGURE 21-2 Corresponding sagittal T2 shows a truncated spinal cord

with hydromyelia and absence of most of the sacrum in a patient with type

FIGURE 21-3 Frontal radiograph in a different patient shows complete

absence of the sacrum

FIGURE 21-4 Coronal T2 in a different patient shows a truncated cord

terminating at a high level (arrow ) in a patient with scoliosis.

FIGURE 21-5 Midsagittal T2, in a different patient with type 2

syndrome, shows cord terminating in a cyst at agenesis level

FIGURE 21-6 Midsagittal T1, in a different patient with type 2

syndrome, shows absent distal sacrum, small intraspinal lipoma, and a

Nievelstein RA, Valk J, Smit LM, Vermeij-Keers C MR of the caudal regression

syndrome: embryologic implications AJNR Am J Neuroradiol 1994;15:1021.

Diastematomyelia (Split-Cord Malformation)

Type 2 (internal, 50%): milder form with single dural tube and

no mesenchymal band, only splitting of cord Generallyasymptomatic

Diastematomyelia is seen in 5% of scoliosis cases and in ~30% ofpatients with myelomeningoceles and is more common in females.Fifty percent of these lesions occur in the thoracic spine and 50% inthe lumbar region

Most hemicords reunite into a single one inferior to the splitting

Diastematomyelias may be associated with syringomyelia in one orboth hemicords or above or below level of splitting, and the type 2generally becomes symptomatic only when a syrinx is present

Vertebral body abnormalities (generally of segmentation) andoverlying skin lesions (hairy patch and hemangiomas are typical inthe type 1) are seen in the majority of patients with diastematomyelia

FIGURE 21-7 Axial T2 in a patient with type 1 disease shows a thin

osseous bar splitting the spinal cord into two hemicords, each with a set ofanterior and posterior nerve roots

FIGURE 21-8 Sagittal T2 in a different patient shows an osseous bar

(arrow) with a low position of the spinal cord, a syrinx, and a lipoma at the level of the split (arrowhead).

FIGURE 21-9 Axial CT, in a different patient, shows a bar that

terminates anteriorly in a pseudoarticulation (arrow), which will make its

removal easier

FIGURE 21-10 Coronal CT, in the same patient, shows the bar (arrow)

and an intraspinal lipoma (arrowhead).

FIGURE 21-11 Axial T2 in a different patient with type 2 disease shows

that the right hemicord contains a cyst

FIGURE 21-12 Axial T2, in a different patient with type 2 disease, shows

that the left hemicord has an associated lipoma (arrow) posteriorly.

SUGGESTED READING

malformations—pictorial review AJR Am J Roentgenol 2010;194:S26–S37.

Dermoid and Epidermoid

Key Facts

These masses account for 3% to 17% of all spinal tumors in children,and 20% to 30% are associated with a dermal sinus tract Themajority are developmental, but they may occasionally be iatrogenic

In the spine, dermoids are more common than epidermoids

Histologically, an epidermoid has a fibrous capsule and squamousepithelium, and a dermoid contains skin appendages (hair folliclesand sebaceous and sweat glands)

Chemical meningitis occurs secondary to their rupture They maybecome infected through a dermal sinus tract and show contrastenhancement; infection may be subclinical and contrast may beindicated in all

Most common location for both lesions is the lumbosacral spine(region of filum terminale and conus medullaris)

Epidermoids contain liquid cholesterol and may be difficult tovisualize by MRI; dermoids contain solid cholesterol and have signalintensities similar to fat but may have cystic components or becompletely cystic and indistinguishable from epidermoids

Main differential diagnosis: teratoma, arachnoid cyst, and neurentericcyst

FIGURE 21-13 Midsagittal T2 shows an epidermoid (arrows) at the L5

level that is nearly isointense to CSF

FIGURE 21-14 Corresponding postcontrast T1 shows that the mass

approximates CSF intensity and does not enhance

FIGURE 21-15 Midsagittal noncontrast T1, in a different patient, shows

a complex, partially cystic, and fatty dermoid in the filum terminale andconus medullaris

FIGURE 21-16 Sagittal T2 in a different patient shows a large,

heterogeneous dermoid with a small amount of layering blood (arrow).

FIGURE 21-17 Midsagittal T2, in a different patient with fever, shows a

complex and large dermoid with a dermal sinus tract

FIGURE 21-18 Corresponding postcontrast T1 shows abnormal, diffuse,

and marked enhancement of the lesion

Key Facts

A filar lipoma is the most common intraspinal lipoma, occurs in 1%

to 6% of the population, and is an incidental and asymptomaticfinding in 95% of patients

With a filar lipoma, the filum terminale is thickened (generally, itsnormal size should not exceed that of neighboring nerve roots) andhas fat within it

In the presence of a filar lipoma, if the conus medullaris is normal inposition, then the findings are probably not clinically significant;however, if the conus medullaris is abnormally low, consider thediagnosis of tight filum terminale syndrome where patients mostcommonly present with urological or bowel complains, lowerextremity pain, and back pain

Intradural lipomas are rare and are mostly found in the cervical region

in children and thoracic region in adults but may occur anywhere inthe spine; most become symptomatic by 5 years of age and result inparesis, spasticity, sensory loss, weakness, and bowel/bladderdysfunction

Main differential diagnosis: dermoid/epidermoid and teratoma

FIGURE 21-19 Sagittal T1 shows a filar lipoma (arrow) with a normal

termination of the conus medullaris

FIGURE 21-20 Midsagittal T1, in a different patient, shows a bright

intraspinal lipoma inseparable from the dorsal surface of a mildly positioned conus medullaris The bones are intact

low-FIGURE 21-21 Corresponding fat-suppressed T2 shows loss of signal

from the lipoma

FIGURE 21-22 Sagittal CT in a different patient shows a large cervical

lipoma with fat density encroaching on the posterior fossa There has beenprior occipitocervical decompression

FIGURE 21-23 Corresponding sagittal noncontrast T1 shows the lipoma

to have the same signal as that of the subcutaneous fat

FIGURE 21-24 Sagittal noncontrast T1 in a different patient shows a

large thoracic lipoma with evidence of prior surgery

SUGGESTED READINGS

prevalence, natural history, and conus position J Neurosurg Pediatr

In a lipomyelocele, meninges and neural placode are located at thelevel of a spina bifida but covered by a lipoma and skin

In a lipomyelomeningocele, the meninges and neural placodeprotrude through a bone opening but are covered by a lipoma andskin; this lipoma is in direct contact with the surface of the neuralplacode, and the patients have a prominent mass in the low back.They have a better prognosis than do open dysraphisms and are notassociated with Chiari II because there is no CSF leak

Both lesions may be detected at birth or be mostly clinically silentand not found until adulthood