Differential Diagnosis of Dementia Flashcards

(46 cards)

1
Q

What is the work-up in suspected dementia?

A
  1. Suspicion of dementia
  2. Rule out metabolic/pscyhiatric causes
  3. Structural imaging
  4. CT prefered - pacemaker, claustrophobia, very old age
  5. MR prefered - young age, rapid progression
  6. If negative, consider SPECT/PET
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2
Q

What can psychiatric disorder present with?

A

Cognitive decline or alterations in personality which is due to neurodegeneration

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3
Q

Why should structural imaging be performed once?

A

To rule out whether the patient has a tumour or hydrocephalus or haematoma compressing the brain tissue

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4
Q

What is CT used to rule out?

A

Sub-dural haemotoma

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5
Q

What is observed in CADASIL?

A

Anterior temporal lesions

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6
Q

What can the atrophy pattern be?

A
  1. Focal

2. Generalised

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7
Q

What brain region is involved in Alzheimer’s or PSP?

A
  1. Alzheimer’s = medial temporal lobe

2. PSP = mesencephalon

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8
Q

What is the routine MRI protocol?

A

3D T1-weighted images (+ cor MPR)
– evaluation of the medial temporal lobe (MTA)
• axial FLAIR & T2 TSE
– hypoxic/ischaemic (white matter) pathology
• axial T2* gradient-echo (or SWI)
– detection of micro-bleeds and calcification
• DWI (Creutzfeld-Jacob)

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9
Q

What is the structural reporting for MRI?

A
  1. Swelling
    - Infection, paraneoplastic
  2. Primary GM loss
    - AD, FTD, Parkinsonian syndromes
  3. Vascular pathology
    - Infarcts, lacunes, WMC (CAA, CADASIL)
  4. Primary WM disease
    - Leukodystrophies, MS, FXTAS
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10
Q

What is FLAIR and T2 used to look for?

A

Anything white in the brain, e.g. signal lesions due to ischaemia, dystrophy

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11
Q

What is T2* gradient echo used to look at?

A

Siderosis

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12
Q

What is DWI used to pick up?

A

Silent ischaemia

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13
Q

What is the structured reporting - swelling?

A
  1. Neoplastic
    - gliomatosis cerebri, intravascular lymphoma
  2. Autoimmune Limbic Encphalitis
    - paraneoplastic, Hashimoto, VGKC, anti-NMDA
  3. Infections:
    - PML, herpes
  4. NPH (rarely shunt-responsive)
  5. Vascilar
    - dural AVF, AVM
  6. RPLS/PRES
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14
Q

What is the structured reporting - primary WM?

A
Infectious
– HIV, Whipple, syphilis
• Inflammatory
– MS, sarcoid, coeliac disease
• Leukodystrophy
– mitochondrial, peroxisomal
– FXTAS, vanishing white matter (VWM)
– adult polyglucogan body disease
• Toxic/metabolic
– CO, vitamin B, heroin
– delayed post-hypoxic demyelination
• Trauma
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15
Q

What is typical of CJD?

A

DWI has multi-focal areas of high signal in the cortex

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16
Q

Where is the pathology found in other patients with CJD?

A
  1. Stratium
  2. Putamen
  3. Caudate
  4. Sometimes in the thalamus
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17
Q

What is the structured reporting - primary GM

A
Alzheimer
– mediotemporal, posterior variant
• FTD
– semantic, aphasic, frontal, right-temporal
• Parkinsonian
– DLB, PSP, MSA
• Other movement disorders
– Huntington, NBIA, Wilson
• Prion disease
– CJD, FFI, GSS
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18
Q

What brain regions do PSP and MSA affect?

A
  1. PSP = midbrain

2. MSA = pons

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19
Q

What does plaques formation interfere with?

A

Functioning of the synapses

20
Q

What happens in the early stage of AD?

A

Tau is stained in the hippocampus especially in the entorhinal cortex

21
Q

What does parahippocampal gyrus provide?

A

Input to the hippocampus

22
Q

What can be observed on imaging for AD?

A

Tissue loss by hippocampi getting smaller and the surrounding spaces widening

23
Q

What can you infer tissue loss from?

A

Expansion of CSF spaces

24
Q

What can be observed on PET scan?

A

Abnormal protein accumulation

25
When do you see abnormal pattern?
Do not see the distinction between white and grey matter
26
What do modern scanners have?
Multiple detectors - very thin slices in a matter of seconds and reconstruct in a different plane
27
What is medial temporal lobe atrophy (MTA) score of 1 a landmark of?
Help identify where the hippocampus is 09
28
What is the MTA?
1. < 75 years score > 1.5 abnormal | 2. > 75 years score > 2 abnormal
29
What is visual rating - issues?
``` Advantage: quick and accessible – online and printed references • Depending on scan protocol – coronal plane, high-contrast T1 • Training of radiologists – ECNR, Erasmus, ESNR, ECR, etc. – interpretation: confounding, bias • Lack of subtlety – need finer grain / more steps in scale ```
30
What is VBM?
o Where you register all of the brain to standard space and then compare the densities of grey matter in various regions in the brain o Correlate the grey matter densities with the scores and when you use the MTA scale of 1-4 – get a very nice correlation with the hippocampus in finding the amount of atrophy o It is very specific it doesn’t correspond with atrophy in other place
31
Hippocampal volume - automated
o Can calculate the volume of the hippocampus o Segmentation o Hippocampus has a volume of 3800 square mm
32
What are the unresolved issues for MTA?
• Implementation of volumetric analysis – better understanding of impact by scan quality – move from workstations to scanner console • Visual analysis: training of radiologists – from training to certification? • Interpretation issues – normative data not standardized / available • Integration with other data – MRI: vascular burden, other ND features (including AD) – non-imaging: CSF, genetic, clinical
33
WHAT IS FTLD semantic?
o Affects the left temporal lobe o Hippocampus is very atrophied – grade 4 if not 5 o Asymmetry – from posterior to anterior o Differences in score of more than 1 o Present relatively late
34
What is Bilateral DD, other MR findings, clinical clues and additional tests ?
1. DD = AD, Hippocampal sclerosis, FTLD 2. MR findings: Temporo-parietal atrophy, isolated finding, temporal pole or frontal atrophy, diffuse cortical atrophy 3. clinical cluues = episodic memory loss, behavioural, language 4. Additional tests = CSF, FDG, PIB FDG - frontal hypoperfusion Dopamine PET/SPECT
35
What is Unilateral DD, other MR findings, clinical clues and additional tests ?
1. DD = FTLD, Mesial temporal sclerosis 2. MR findings = Anterior more than frontal, temporal pole, frontal lobe atrophy High signal hippocampus 3. Clinical clues = Behavioural, language, Epilepsy 4. Additional tests = FDG frontal hypoperfusion EEG
36
What is the patterns of atrophy in Alzheimers?
• Medio-temporal – Hippocampus, parahippocampus – APOE-4 positive, senile age, memory • Posterior pattern – posterior cingulate, interparietal sulcus – APOE-4 negative, presenile, visuo-spatial • Atypical patterns – frontal or occipital predominance (Benton) – behavioral or visual symptoms • DD with FTLD and DLB
37
What is the MRI findings, clinical clues and additional test for AD?
1. MRI findings: symmetrical (usually) biparietal atrophy (+/- occipital); hippocampal atrophy relatively late feature 2. Clinical clues: Memory not completely normal, visuospatial deficits 3. Additional tests: CSF, PIB
38
What is the MRI findings, clinical clues and additional test for DLB?
1. MRI findings: generalised atrophy, parietal and occipital 2. Clinical clues: extrapyramidal signs, hallucinations, fluctuations 3. Additional test: Dopamine imaging
39
What is the MRI findings, clinical clues and additional test for CBD?
1. MRI findings: Aysmmetric parietal (and frontal) atrophy 2. Clinical clues: asymmetrical limb praxis, myoclonus 3. Additional test: Dopamine imaging, FDG-PET
40
What is the MRI findings, clinical clues and additional test for CJD?
1. MRI findings: FLAIR and DWI abnormal - cortical ribbon or stratium. May have generalised cerebral and cerebellar atrophy 2. Clinical clues: Rapid decline, myoclonus 3. Additional test: EEG (may be normal), CSF (tau&14-3-3)
41
What is the MRI findings, clinical clues and additional test for cerebrovascular?
1. MRI findings: FLAIR/T2 signal change, watershed distribution 2. Clinical clues: subcortical clinical features; stroke 3. Additional: vascular risk factors
42
What is the structured reporting - vascular?
``` Small vessel disease – extensive WML, multiple lacunes – specific diseases: CADASIL, CAA • Large vessel pathology – strategic infracts, dominant hemisphere • Systemic causes of ischemia – vasulitis – mitochondrial – post-hypoxic demyelination ```
43
What is vascular disease and dementia?
combination of infarcts & AD best predicts dementia (Nun & MRC-CFAS studies) – “double hit” concept • WML stepping stone for clinical AD – subclinical damage lowers threshold • atherosclerosis accelerates AD pathology • amyloid deposits in vessels & parenchyma – lobar microbleeds in CAA and AD – central MBs in hypertension
44
What medications is used for MTA and severe WMH?
1. MTA = cholinesterase inhibitors | 2. Severe WMH = antihypertensive treatment
45
What is ARIA?
Amyloid Related Imaging Abnormalities
46
What is the take home points?
``` Exclude structural lesions – WM disease and swelling • Neurodegeneration – AD signature – medio-temporal OR posterior cingulate • Differential atrophy patterns – FTD, PSP, MSA (DLB) • VaD of vascular co-morbidity? – separate target for Rx • Functional PET/MRI techniques – bridge gap between amyloid & atrophy ```