Differentiating diagnosis of WML Flashcards
What are the 3 areas of differentiating diagnosis of WML?
- Multiple Sclerosis
- Inflammation
- Small vessel disease
What is the problem for differentiating diagnosis of MS?
No single clinical feature or test is sufficient [clinical or Imaging]
What are the diagnostic criteria for MS?
- Dissemination in space
- Dissemination in time
- Reasonable exclusion of alternatives
What are the diagnostic criteria of MS based on?
Based on the evolution of the disease of the patients
What does dissemination in space mean?
Not always in the same area in the brain
- more than one area is affected
What does dissemination in time mean?
The symptoms should not be happening at the same time
Misdiagnosis and Differential Diagnosis
- Potential differential diagnosis is broad
2. Misdiagnosis is an issue
Why are misdiagnosis an issue?
- Often common conditions with nonspecific symptoms, signs, MRI findings
- NMOSD
- Can have harmful consequences
What does NMOSD stand for?
Neuromyelitis Optica Spectrum Disorder
Why can misdiagnosis have such harmful consequences?
If you misdiagnosis patient, but treat them - expose him to a treatment that is not useful and will not improve and make him worse
Why is over reliance of MRI for neurologist a problem?
- something is written about WM lesions and that is taken as evidence for MS where the clinical evidence may not be there
- As soon as lesions are identified - 4/5 points are made: Vascular, MS, Vasculitis
- There are a number of drugs that do not cure but can stop the disease for a certain time
When do we want to treat MS?
ASAP
you do not want to treat late where cells have died
[pressure not to miss a window]
What are the MR MS pattern?
- Location: immediately adjacent PV, within the cortical, below Sub-cortical, Optic nerve, Corpus Callosum and Spinal Cord
- Shape: Oval, Dawson’s Finger
- Enhancement: First 3-6 weeks
- SWI: CVS, Iron deposition
Where are the lesions of MS found?
Around the vein (venule)
lesions develop around the vein with vein at its centre
Where are veins located?
Perpendicular to the ventricles
What is found adjacent to the cortex?
U fibres [ white matter tract that connect one gyri with the other gryi]
What does enhancing and non-enhancing lesions show?
They have different age
Where is lesion found in the posterior fossa?
Along the internal course [intermedullary course]
What are the 2 cranial nerves of facial colliculus?
5th and 6th
What happens in silent lesions?
lesions that are not manifesting themselves clinically
What are examples of cortical lesions?
- Focal demyelinated plaques in the white matter
- Cortical demyelination
- Demyelinated lesions in the deep grey matter
What imaging modalities are used for Curvilinear lesions?
- PSIR
2. DIR
What are Central Vein Sign (CVS)?
These lesions have vessel in their centre
What Imaging modality is good for CVS?
FLAIR
What would typically fit with MS lesion?
A lesion that has a venule in its centre
What is SWI good to look for?
Signal change beyond the vessel?
[Intralesional Susceptibility Signal]
ISS at 3T
Non-enhancing: 48-50% had a rim (magnetic susceptibility)
Enhancing: 58-60% had a rim
SWI in Focal Lesions
Magnetic susceptibility increases rapidly as it changes from enhanced to non-enhanced
High susceptibility values during first 2-4 years
Then gradually decreases (susceptibility similar to NAWM)
What are the features for Spinal cord lesions?
Typical:
- unifocal
- multifocal
Atypical
- tumefactive
- diffuse
What are the pathology for NMO disease?
- Inflammation
- Astrocytopathy
- Myelin relatively preserved, damage secondary
What are the diagnosis of NMO?
- Optic neuritis: initial event in the young
- Acute myelitis: initial event in the older
- AQP4 AB: but negative 20-30%
What is Aquaporin 4 good for?
channeling water
regulates water going in and out
What is Aquaporin 4?
- Most abundant CNS water channel
2. Concentrated in astrocytic foot processes
What are the features of AQP4 Channelopathy?
- Female > 80%
- Non-Caucasian predominance
- Relapsing if untreated
- Severe disability and high mortality
- Associated with other auto-immunity
- Onset with both ON + TM uncommon
What are the features of Myelin Oligodendrocyte Glycoprotein (MOG)-AB disease?
- Female: Male equal
- No non-caucasian predomunance
- ~50% monophasic
- Better outcome than AQP4-Ab disease
- Not associated with other auto-immunity
- Onset with both ON + TM common
- Overlap with ADEM (monophasic & relapsin)
Where is MOG-igG-seropositive more frequent in?
Paediatric patients
What is a large proportion found in the NMOSD?
AQP4-Ab disease
What are the features of NMO?
SC Lesions:
- Extent > 3 segments
- Central grey matter
- Swelling
- Partial enhancement
- Atrophy & Cavity formation
What are specific brain lesions of NMO?
- Medullary periaqueductal grey
2. Bilat hypothalamus
What are the brain lesions features of NMO?
- Present 60%
- Location: PV (increase in AQP4 expression)
- Extensive
- Multiple, patchy, enhancing (cloud-like enhancement) in 9-% of pat with CE
- CC: splenium, diffuse, oedematous, heterogenous
What is typically found in cloud-like enhancement?
NMO
What is not found in cortical lesions?
NMO
What differentiates MS from NMOSD?
Multiple lesions at the cut-off of 54%
If more than half of the lesions have a central vein [MS]
What are Atypical lesions
- Finger-like extensions
- Quite broad
- Cloud-like enhancement
NMO: 2015 diagnostic criteria
- At least one core clinical characteristic
2. A positive test for aquaporin
Area postrema
Get hiccups
MR requirements (AQP4-IgG -ve/unknown)
Acute optic neuritis
> 1/2 ON length or optic chiasm
MR requirements (AQP4-IgG -ve/unknown)
Acute myelitis
Intramedullary lesions:
>3 contiguous segments (LETM)
>3 contiguous segments SC atrophy (history of myelitis)
MR requirements (AQP4-IgG -ve/unknown)
Acute brainstem syndrome
Periependymal brainstem lesions
MOG-ab similar to AQP4-ab additionally:
- conus involvement (isolated sphincter and erectile dysfunction)
- Fluffy lesions (adults, or ADEM attacks childhood)
- Bilateral cerebellar peduncle
DD from MS
- > 1 lesion adjacent to body of lat ventricle and in inferior temporal lobe
- S-shaped U-fibre lesion
- Dawson’s finger-type lesion
What are the best classifiers between MOG and MS?
MS:
- Ovoid lesions PV (body of lateral ventricles)
- Dawson’s fingers
- T1 hypointense lesions
MOG:
- Fluffy lesions
- 3< lesions (MOG AB)
WML
Incidental focal WML > MS
prevalence (20-40 years):
1. MS <0.1%
2. Incidental WML 5-10%
Small Vessel Disease
Pathology not directly visualised
What are MR of Small Vessel Disease?
- White matter hyperintensities
- Recent subcortical infarcts (Lacunes)
- Microhaemorrhages
- Perivascular spaces
- Atrophy
What is the definition of Small Vessel Disease?
- Sporadic, intrinsic process, affecting:
- Small arteries & arterioles
- Capillaries
- Small veins
Clinically: often silent, developping over years before manifesting clinically
Pontine Lesions
- Symmetric
- Parallel
- Affect certain structures - Medial Lemniscus
What is CADASIL?
Hereditary small vessel disease
What are Lacunes?
Atypical for MS
What are the evolution of WMH & Lacunes?
- WMH appear in vascular end zones
- Progress proximally along perforating arteries
- Lacunes appear at WMH edge
- WMH expand around Lacune
Microbleeds
- Small areas of signal void
- 2-5mm in diameter, but up to 10mm
- Associated blooming on T2*-w
- Perivascular collections of hemosiderin-laden macrophages
What does Microbleeds cause?
- SVD (leakage)
- Cerebral amyloid angiopathy (CAA)
- AB amyloid deposition in vessel wall
- Cortical & leptomeningeal arteries, arterioles (veins)
Assistance in DD
Spinal MR:
- No incidental findings
- Differential diagnosis of intramedullary lesions
- MS: Circumscribed/diffuse changes
- SVD: No lesions
- CADASIL: No lesions
