Differential diagnostics DLB

Question 1

Neuropathology differentials

Answer 1

Lewy bodies are found in 20-35% older persons with dementia, not all of them have DLB
- Lewy bodies are not common in healthy persons

AD pathology
- amyloid plaques: in up to 75-90% of patients with DLB
- Tangles less common in DLB
- Amyloid plaques less frequent in PDD

Distinction DLB and PD
- Loss neurons in substantia nigra more extensive in PD
- More LB in posterior temporal areas in DLB

Question 2

Atrophy differentials

Answer 2

DLB;
- Atrophy in temporal, parietal, occipital areas
- More white matter abnormalities in posterior regions

PDD
- Atrophy frontal areas
- More white matter abnormalities in frontal regions

Both:
- cerebral blood flow and glucose uptake reduced in posterior areas

Question 3

DLB diagnostic criteria

Answer 3

A. Interferes w ADL, deficit in attention, EF and visuospatial ability tend to occur early and prominent

Clinical features (two om);
- Fluctuating cognition with pronounced variations in attention and alertness
- Recurrent visual hallucinations that are typically well formed and detailed
- REM sleep behaviour disorder, which may precede cognitive decline
- One or more spontaneous cardinal features of parkinsonism, namely, bradykinesia, rest tremor and rigidity

Question 4

Indicative biomarkers DLB

Answer 4

• Reduced dopamine transporter uptake in basal ganglia on SPECT or PET
• Abnormal (low uptake) 123iodine-MIBG myocardial scintigraphy (blood flow to heart muscle, damaged in DLB)
• Polysomnographic confirmation of REM sleep without atonia (key early sign of DLB)

Probable DLB diagnosis if 1 clinical and one om indicative biomarkers are observed (or 2 clinical symptoms)

Question 5

Visual hallucinations

Answer 5

Fully formed detailed objects, people or animals. Mostly visual
- Auditory, tactile, olfactory hallucinations less common

Observed in 22-89% of cases DLB, similar for PDD
- In AD; 11-28% of cases but way later after diagnosis (5-7 yrs). Used to distinguish between AD and DLB
- Can occur several times per day, most in night/evening
- Often delusions (Capgras) of theft, infidelity etc

DLB with visual hallucinations typically have more severe cognitive and functional impairments

Question 6

Fluctuations in cognitive functioning and arousal

Answer 6

Fluctuations in attention, incoherent speech, impaired
awareness of surroundings, staring into space, “switched off”. Reported prevalence: 10% - 80%

used to distinguish between AD and DLB
- In studies on clinical overlap, the symptoms occur in VH, fluctuations and parkinsonism in 35% of DLB, 0% of AD

Question 7

REM sleep behaviour disorder

Answer 7

70-75% of DLB have sleep disorder
- Mostly REM, loss of atonia
- Often seen as early sign of DLB (12 yr risk of developing it is 52%)

Question 8

Parkinsonism

Answer 8

in 70 – 100% of patients with DLB

• rigidity, bradykinesia, shuffling gait, stooped posture, masked face
• tremor less common
• severity varies
• usually less severe in DLB than in PD
• patients may report frequent unexplained falls
• Parkinsonism must be spontaneous, i.e. not attributable to medication