384.1 🎓 醫孞生版

384.1.0.1 📌 䞀頁重點

384.1.0.1.1 DLB Epidemiology
  • 3rd most common dementia (after AD, vascular)
  • M > F slightly
  • Mean onset 50-85
  • Survival 5-8 years
384.1.0.1.2 Core Clinical Features (4)
  1. Fluctuating cognition (alertness, attention) — sometimes lucid, sometimes severely impaired
  2. Visual hallucinations — well-formed (people, animals), recurrent, often non-threatening
  3. REM behavior disorder (RBD) — acting out dreams (often prodromal)
  4. Parkinsonism — bradykinesia, rigidity, postural instability; tremor less prominent

384.1.1 Supportive Clinical

  • Severe sensitivity to antipsychotics (can be life-threatening — extrapyramidal crisis)
  • Autonomic dysfunction (orthostatic hypotension, urinary, constipation)
  • Hypersomnia, daytime sleepiness
  • Non-visual hallucinations
  • Apathy, anxiety, depression, delusions
  • Repeated falls, syncope
384.1.1.0.1 DLB vs PD Dementia (PDD)
  • Both synucleinopathies
  • Same pathology
  • Distinguished by timing:
    • DLB: cognitive impairment within 1 year of or before parkinsonism
    • PDD: motor symptoms > 1 year before cognitive impairment
  • Both treated similarly
384.1.1.0.2 Pathology
  • α-synuclein Lewy bodies (similar to PD but more diffuse, cortical)
  • Often co-exists with AD pathology (Aβ plaques)
  • Mixed Lewy body + AD pathology in many
384.1.1.0.3 Diagnosis

384.1.2 Clinical Criteria (McKeith 2017)

  • Probable DLB: dementia + ≥ 2 core features
  • Possible DLB: dementia + 1 core feature + ≥ 1 indicative biomarker

384.1.3 Indicative Biomarkers

  • DaT-SCAN abnormal (reduced dopamine transporter)
  • MIBG cardiac scintigraphy decreased (vs preserved in MSA, AD)
  • Polysomnography confirms RBD

384.1.4 Supportive Biomarkers

  • Relative preservation of medial temporal lobe on MRI
  • Generalized low uptake on FDG-PET (especially occipital — distinguishes from AD)
  • Cingulate island sign
384.1.4.0.1 Treatment

384.1.5 Cognitive

  • Cholinesterase inhibitors — DLB more responsive than AD!
    • Rivastigmine (Exelon)
    • Donepezil (Aricept)
  • Memantine (modest)

384.1.6 Visual Hallucinations

  • Often tolerable if non-distressing
  • Pimavanserin (Nuplazid) — selective 5HT-2A inverse agonist; FDA-approved for PD psychosis
  • Low-dose quetiapine or clozapine if needed
  • AVOID typical antipsychotics + olanzapine + risperidone (severe sensitivity, can be fatal!)

384.1.7 Parkinsonism

  • Levodopa cautiously (may worsen hallucinations)
  • Lower doses

384.1.8 RBD

  • Melatonin 3-12 mg HS
  • Clonazepam 0.25-1 mg HS
  • Safety measures

384.1.9 Autonomic Dysfunction

  • Orthostatic: midodrine, fludrocortisone, droxidopa
  • Urinary: avoid anticholinergics
  • Constipation: fiber, laxatives
384.1.9.0.1 Vascular Cognitive Impairment (VCI)

384.1.10 Spectrum

  • Vascular MCI (VaMCI) — mild
  • Vascular dementia (VaD) — full dementia

384.1.11 Subtypes

  • Multi-infarct dementia (multiple strokes)
  • Strategic infarct dementia (key location: thalamus, angular gyrus)
  • Subcortical ischemic vascular dementia (SIVD) — small vessel disease
  • Hemorrhagic dementia (CAA, hypertensive bleeds)
  • Mixed AD-vascular (very common)

384.1.12 Clinical Features

  • Stepwise progression (in classical multi-infarct)
  • Gradual decline in subcortical
  • Subcortical pattern: psychomotor slowing, executive dysfunction, gait disorder, emotional lability
  • Mood + behavior changes
  • Pseudobulbar
  • Focal neurological signs
  • Vascular risk factors

384.1.13 Diagnosis

  • Cognitive impairment
  • Vascular brain lesions on imaging
  • Temporal/anatomic relationship
  • Often coexists with AD

384.1.14 Treatment

  • No specific DMT for VCI (cholinesterase inhibitors limited evidence)
  • Aggressive vascular risk factor management:
    • BP control (most important!)
    • Statins
    • Diabetes
    • Smoking
    • Diet, exercise
  • Antiplatelet for non-cardioembolic stroke prevention
  • Anticoagulation for AF
  • Carotid intervention if indicated

384.1.14.1 🩺 床邊速查

  • DLB: 4 core (fluctuation + visual hallucinations + RBD + parkinsonism)
  • DLB vs PDD: timing (DLB cognitive within 1 yr)
  • DLB Tx: ChEI + pimavanserin/low-dose atypical for psychosis; AVOID typical antipsychotics!
  • VCI: stepwise (multi-infarct) or gradual (subcortical)
  • Mixed AD-vascular very common
  • VCI Tx: vascular risk factor management aggressive