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KEY FACTS

Terminology
- Primary demyelinating disease of CNS with multiple lesions disseminated over time & space - Concomitant intracranial lesions in periventricular, subcallosal, brainstem, or cerebellar white matter
Imaging
- Isolated spinal cord disease (10-20%)
- Cervical segment is most commonly affected - Dorsolateral aspect of cord - < 1/2 of cross-sectional area of spinal cord - < 2 vertebral segments in length
- Sagittal & axial T1WI/T2WI sequences with gadolinium - Lesions typically oval, peripheral, & asymmetric - Discrete vs. vague hyperintense lesions - Enhancement lasts 1-2 months but does not reflect disease progression
Top Differential Diagnoses
- Acute disseminated encephalomyelitis
- Neuromyelitis optica spectrum disorders
- Myelin oligodendrocyte glycoprotein antibody disorder
- Idiopathic transverse myelitis
- Intramedullary neoplasm
- Spinal cord infarct
Pathology
- Autoimmune, cell-mediated inflammatory process focused on CNS myelin
Clinical Issues
- Peak onset: 20-40 years - Adult females more susceptible than males (1.7:1)
- Multiple clinical presentations - Relapsing remitting (RR) - Secondary progressive (SP) - Primary progressive (PP) - Progressive relapsing (PR)
Diagnostic Checklist
- Imaging findings must be correlated with clinical & laboratory features to confirm diagnosis

TERMINOLOGY

Abbreviations
- Spinal cord multiple sclerosis (MS)
Definitions
- Primary demyelinating disease of CNS with multiple lesions disseminated over time & space

IMAGING

General Features

Best diagnostic clue

- Concomitant T2-hyperintense lesions in ≥ 2 of 4 areas of CNS: Periventricular, cortical or juxtacortical, infratentorial, & spinal cord

Location

- Lesions solitary or multifocal
        - Isolated spinal cord disease in 10-20%
- Cervical segment is most commonly affected (2/3 of cord lesions)
- Lesions frequently in dorsolateral cord
- Does not respect gray-white boundary

Size

- < 1/2 of cross-sectional area of spinal cord
- < 2 vertebral segments in length

Morphology

- Wedge-shaped on axial MR
        - Apex directed centrally

MR Findings

T1WI

- Iso- to hypointense lesions
        - In cord (unlike brain), rarely visible as hypointense
        - 30% of brain lesions are dark, "black holes"
- Normal or mild focal cord expansion
        - Cord edema
                  - Resolves after 6-8 weeks

T2WI

- Discrete or ill-defined hyperintense lesions
        - May be related to extent of demyelination
        - Lesions ↑ in size due to edema associated with inflammatory infiltrates → reach max size at 4 weeks
        - Slow ↓ in size over 6-8 weeks as edema resolves ± remyelination
- Lesions typically oval, peripheral, & asymmetric

PD/intermediate
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- Hyperintense lesions
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STIR

- Improved lesion detection, more artifact

FLAIR

- Lower lesion sensitivity compared to STIR

DWI

- ↑ mean diffusivity, ↓ fractional anisotropy in plaques & areas without T2 abnormality

T1WI C+

- Variable
        - Homogeneous, nodular, or ring enhancement during acute or subacute phase
                  - Enhancement lasts 1-2 months
                  - Does not reflect disease progression
        - No enhancement during chronic phase

MRS

- ↓ N-acetylaspartate level
- ↑ choline levels, even in normal-appearing white matter

Cord atrophy - Usually in late stage - May be seen in early disease course - Useful for monitoring disease progression & therapeutic efficacy - Correlates with clinical disability
fMRI - Tactile-associated cervical cord fMRI activity ↑ in relapse-onset MS patients - Overactivation more prominent in patients with more severe locomotor disability - Suggests abnormality of cord functional properties may be among factors associated with clinical status of MS patient

Nonvascular Interventions
- Myelography
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- Nonspecific mild cord expansion
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Other Modality Findings
- Magnetization transfer (MT) imaging - ↓ MT ratio in spinal cord - Better correlation with disability & axonal loss - ↓ MT ratios in enhancement patterns in which myelin known to be ↓ histopathologically

Imaging Recommendations

Best imaging tool

- T1WI/T2WI spinal cord MR in sagittal & axial planes with gadolinium

DIFFERENTIAL DIAGNOSIS

Acute Disseminated Encephalomyelitis
- Para-/postinfectious immune-mediated inflammatory disorder of spinal cord white matter
- Frequently preceding infection 4-12 days before onset
- Usually monophasic
Syringohydromyelia
- Central cystic lesion
- CSF intensity on all sequences
- No abnormal enhancement
Neuromyelitis Optica Spectrum Disorders
- Autoimmune inflammatory disorder involving myelin of neurons of optic nerves & spinal cord
- Longitudinally extensive cord T2 hyperintensity + optic nerve enhancement
- T2 abnormality involves entire cross section of cord
- Limited brain involvement
Myelin Oligodendrocyte Glycoprotein Antibody Disease
- Autoimmune inflammatory disorder involving neuronal myelin of brain, optic nerves, &/or spinal cord
- Often longitudinally extensive
- Predilection for conus
Idiopathic Transverse Myelitis
- Longitudinally extensive, > 2/3 of cord cross-sectional area
- Lesion centrally located, variable enhancement
- No associated intracranial lesions
- Diagnosis of exclusion
Intramedullary Neoplasm
- Cord expansion, peritumoral edema, cystic ± hemorrhagic components
- Entire cross section of spinal cord
- Diffuse or partial enhancement
Spinal Cord Infarction
- Sudden onset of symptoms
- Positive diffusion restriction
- Posterior columns typically spared in anterior spinal infarct

PATHOLOGY

General Features

Etiology

- Autoimmune, cell-mediated inflammatory process focused on CNS myelin
        - Infectious agents may play primary or secondary role
                  - Humoral mechanism: Cross reactivity between infectious & self-epitopes
- May be association between MS & altered venous return due to multiple extracranial venous strictures
        - Hampered cerebrospinal venous drainage in patients with MS determines complex hemodynamic picture → chronic cerebrospinal venous insufficiency (CCSVI)
                  - Multiple substitute circles with very high incidence of reflux in both intra-/extracranial venous segments
                  - Loss of postural regulation of cerebral venous outflow
        - Primary progressive (PP) course related to CCSVI pattern differs significantly from relapsing remitting (RR) & secondary progressive (SP) → location of venous obstruction plays role in clinical course
                  - Obstruction at several levels of azygous vein & of lumbar plexuses
                  - → venous blood of cord can be drained only in upward direction & is shunted toward venous plexuses inside spine
        - ↑ cerebral blood flow/volume & ↓ mean transit time (compared with baseline values before relapse) precede development of plaques
        - Susceptibility-weighted imaging → venous blood in cerebral veins of patients with MS is less deoxygenated compared with healthy controls
        - Previously, these findings interpreted as sign of local flow disturbances mediated by inflammatory & neurodegenerative processes
                  - However, may be attributable to recent findings of significant stenoses in extracranial veins draining brain & spinal cord

Genetics

- May be inherited as complex multifactorial disorder resulting from interaction of genetic & environmental factors
        - Estimated risk to siblings of proband ~ 3.0-5.0%, ↑ to 29.5% if 1 or both parents have MS
        - Risk to offspring of person with MS is 2.0-3.0% & higher if both parents have MS

Associated abnormalities

- 90% incidence of associated intracranial lesions
- Neurofibromatosis type 1
- Different serum thyroid hormone & complement C3, C4, & CH50 levels in neuromyelitis optica vs. MS
        - Thyroid hormones may play different role in modulating complement activation in MS & neuromyelitis optica

Focal regions of demyelination of varying size & age scattered throughout CNS white matter

Staging, Grading, & Classification
- McDonald criteria (2001, revised in 2005 & 2017) widely used for adult MS diagnosis - Has also been shown to be useful for pediatric MS diagnosis
- Relies on lesion dissemination in both time & space
- Dissemination in space - Demonstrated by ≥ 1 T2-hyperintense lesions that are characteristic of MS in ≥ 2 of 4 areas of CNS - Periventricular, cortical or juxtacortical, infratentorial brain regions, & spinal cord
- Dissemination in time - Simultaneous presence of gadolinium-enhancing & nonenhancing lesions at any time - New T2-hyperintense or gadolinium-enhancing lesion on follow-up MR with reference to baseline scan, irrespective of timing of baseline MR
Microscopic Features
- Discrete lesions of myelin destruction
- Active lesions with macrophages & lymphocytes
- Chronic lesions with gliosis & cavitation
- Perivascular cuffs of lymphocytes & mononuclear cells
- Involvement of dorsal horns common

CLINICAL ISSUES

Presentation
- Most common signs/symptoms
```
- Cord lesions asymptomatic
- Paresthesia
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- Other signs/symptoms
```
- Muscle weakness, hyperreflexia, gait disturbance
- Bladder/bowel dysfunction
```
- Surveillance includes periodic neurologic examination to track disease progression & periodic brain & spinal cord MRs to monitor disease activity - Additional examination techniques → ambulation index, 25-foot timed walk, & 25-foot walk combined with 9-hole peg test & paced serial auditory addition test

Demographics

Age

- Peak onset: 20-40 years
- Onset < 18 years in 3-5% of MS cases

Sex

- Women more susceptible than men (1.7:1)
        - Men more likely to have progressive relapsing (PR) & SP MS
        - Women more likely to have RR MS
- Both sexes equally affected in PP MS

Ethnicity
```
- Western Europeans have higher risk
```

Epidemiology

- ↑ prevalence farther north from equator
        - 30-80 per 100,000 in northern USA & Europe
        - 6-14 per 100,000 in southern USA & Europe
        - 1 per 100,000 in equatorial regions

Natural History & Prognosis
- Benign: 20% - Complete recovery after 1-2 attacks - Some may experience progressive MS after 10-15 years
- RR: 25% - Distinct periods of new or worsening symptoms alternating with complete or partial recovery - 90% will evolve into progressive MS after 25 years
- SP: 40% - From RR MS - Worsening deficits & disabilities - Incomplete & infrequent remission
- PP: 12% - Steady progression of symptoms - Motor dysfunction common - Primary cord involvement; no distinct attacks
- PR: 3% - Similar to PP MS - Distinct periods of exacerbation but without recovery - High mortality rate
Treatment
- Multiple approved medications include interferon, chemotherapy agents, monoclonal antibodies - Several preparations available of interferon β (interferon β-1b, interferon β-1a) - Inhibition of immune cells - Glatiramer acetate - Synthetic protein similar to myelin protein - Serves as substrate for T cells - Mitoxantrone (chemotherapeutic agent) - Suppression of T lymphocytes & B lymphocytes - Monoclonal antibodies - Natalizumab, alemtuzumab, daclizumab, ocrelizumab - Small-molecule oral agents - Fingolimod, dimethyl fumarate, teriflunomide
- Supportive therapy - Symptomatic treatment of pain, muscle spasms, fatigue, depression, sexual/bladder/bowel dysfunction - Anticholinergics, smooth muscle relaxants
- Physical therapy

DIAGNOSTIC CHECKLIST

Consider
- Multiplanar spine contrast MR ± contrast, including STIR MR
- Brain MR, including high-resolution fast spin-echo T2 through corpus callosum - Gray matter atrophy correlates with disability - Periventricular, subcallosal, brainstem, or cerebellar white matter lesions suggest MS
Image Interpretation Pearls
- Imaging findings must be correlated with clinical & laboratory features to confirm diagnosis
- Acute MS can mimic cord neoplasm

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References

Selected References

Images

Selected Images

Sagittal graphic depicts multiple sclerosis (MS) demyelinating plaques within the cervical spinal cord. Lesions are focal and < 2 vertebral bodies in length, typical of MS.

Sagittal T2WI MR (left) demonstrates a solitary active MS plaque at the C6-C7 level with focal T2 hyperintensity but without significant cord enlargement. Sagittal T1WI C+ FS MR (right) confirms ring enhancement of the focal lesion, consistent with an active MS plaque.

Sagittal T2WI (left), PD (middle), and STIR (right) MR images show multiple short-segment MS plaques within the thoracic spinal cord . Note the relatively improved conspicuity of the plaques on PD and STIR relative to the routine T2 sequence.

Sagittal STIR (left), T2WI (middle), and T1WI C+ FS (right) MR images of the thoracic spine show multiple short-segment foci of T2 hyperintensity in a different patient with MS. Multiple lesions show solid enhancement.

Additional Images

Sagittal T2WI MR in a patient with MS and characteristic brain lesions (not shown) reveals a focal lesion centered at C7 with minimal if any cord enlargement.

Axial T2WI MR in the same patient reveals a lesion in the left hemicord that is focal and does not involve the entire cord diameter, features favoring MS.

Sagittal T2WI (left) and T1WI C+ FS (right) MR images show several T2-hyperintense foci in the cervical cord in this patient with MS. Two of the lesions enhance, reflecting active demyelination .

Sagittal T2WI (left) and T1WI C+ (right) MR images show active enhancing plaque at the C2 level with both focal, well-defined (enhancing) T2 focus and a small amount of surrounding nonenhancing edema .

Sagittal T2WI MR of the cervical cord shows a more discrete demyelinating focus at C3-C4.

Axial T2WI MR of the cervical cord in a different patient shows a poorly defined, wedge-shaped, mildly hyperintense plaque within the right lateral aspect of the cord.

Axial T1WI C+ MR with fat suppression of the cervical cord in a different patient shows right peripheral nodular enhancement.

Sagittal T2WI MR of the cervical cord shows an ill-defined, hyperintense intramedullary lesion at C5-C6.

Sagittal T2WI MR of the cervical spinal cord demonstrates multiple T2-hyperintense foci , some well defined and others ill defined. The multiplicity of lesions and lack of edema or significant cord expansion is typical for demyelinating disease.

Sagittal T1WI C+ MR shows multiple enhancing demyelinating lesions within the cervical spinal cord. Enhancement varies from focal to ill defined . The enhancement pattern changes with evolution of inflammation.

T1WI C+ MR (sagittal on top, axial on bottom) illustrates an incomplete rim-enhancing lesion in the dorsal cervical cord at the C3-C4 level. A 2nd small enhancing focus is noted in the ventral cord at the C6 level .

Sagittal PD FSE MR of the cervical spinal cord demonstrates characteristic ovoid hyperintense intramedullary demyelinating lesions without significant cord expansion.

Axial T1WI C+ MR of the cervical spinal cord depicts focal ring enhancement within an active MS demyelinating lesion.

Sagittal STIR MR shows a focal hyperintense demyelinating plaque within the thoracic cord without significant cord expansion. STIR MR is more sensitive for lesion depiction than T2WI MR at the price of more artifacts.

Sagittal high-resolution GRE MR of the thoracic cord shows multiple areas of ↑ signal in this patient with MS. All lesions are ≤ 2 vertebral bodies in length, typical for MS.

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KEY FACTS

Terminology

Imaging

Top Differential Diagnoses

Pathology

Clinical Issues

Diagnostic Checklist

TERMINOLOGY

Abbreviations

Definitions

IMAGING

General Features

Best diagnostic clue

Location

Size

Morphology

MR Findings

T1WI

T2WI

PD/intermediate

STIR

FLAIR

DWI

T1WI C+

MRS

Nonvascular Interventions

Myelography

Other Modality Findings

Imaging Recommendations

Best imaging tool

DIFFERENTIAL DIAGNOSIS

Myelin Oligodendrocyte Glycoprotein Antibody Disease

PATHOLOGY

General Features

Etiology

Genetics

Associated abnormalities

Staging, Grading, & Classification

Microscopic Features

CLINICAL ISSUES

Presentation

Most common signs/symptoms

Other signs/symptoms

Demographics

Age

Sex

Ethnicity

Epidemiology

Natural History & Prognosis

Treatment

DIAGNOSTIC CHECKLIST

Consider

Image Interpretation Pearls

References

Selected References

Images

Selected Images

Additional Images

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