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Lewy Body DementiaAka: Dementia with Lewy Bodies, DLB

Definition
1. Dementia with visual hallucinations, Parkinsonism
Epidemiology
1. Accounts for 20% of Dementia cases
  1. Second most common cause
2. Mean age of onset: 75 to 80 years old
Pathophysiology
1. Lewy body and Lewy neurites
  1. Eosinophilic cytoplasmic inclusions (alpha-synuclein)
    1. Parkinsonism: substantia nigra, locus ceruleus
    2. Lewy Body Dementia: Frontotemporal cortex
2. Other changes specific to Lewy Body Dementia
  1. Basal forebrain degeneration (cholinergic neurons)
  2. Nigra degeneration (Dopaminergic neurons)
  3. Serotonergic neurons also affected
3. Comparison with Alzheimer's Disease changes
  1. Amyloid Plaques in Alzheimer's and Lewy Body Dementia
  2. Neurofibrillary tangles seen in Alzheimer's only
Clinical features
1. Dementia (cognitive function decline)
2. Core features (2 features required for probable case)
  1. Recurrent visual hallucinations
  2. Fluctuating cognition, alertness and attention
    1. Normal performance in stimulating activity
    2. Transient periods of "blankness"
  3. Parkinsonism
    1. Rigidity, bradykinesia and altered gait are common
    2. Mask-like faces are also seen
    3. Resting Tremor less common than Parkinson's Disease
3. Manifesting signs and symptoms
  1. Syncope
  2. Recurrent falls
  3. Transient loss of consciousness
  4. Delusions
  5. Major Depression
  6. REM Sleep disorder
    1. Associated with Nightmares of being chased
Differential Diagnosis
1. See Dementia
2. Alzheimer's Disease differentiating features
  1. Memory loss is more prominent than in DLB
  2. Visual hallucinations less common in Alzheimer's
  3. Parkinsonism uncommon in Alzheimer's Disease
  4. Minimal cortical atrophy in Lewy Body Dementia
  5. Alzheimer's: MRI involves hippocampus, temporal lobe
Diagnostic Testing
1. Rule-out other cause
  1. See Dementia for diagnostic testing
2. Mini-Mental State Exam (MMSE) findings
  1. Difficult attention and construction
  2. Difficult clock drawing
  3. Memory appears unaffected in early DLB
Management
1. See Dementia Management
2. Avoid cholinergic medications
3. Cholinesterase inhibitors
  1. Effects
    1. Improve apathy and anxiety
    2. Reduce hallucinations and delusions
    3. Improve cognition
  2. Agents
    1. Rivastigmine (Exelon)
    2. Donepezil (Aricept)
    3. Galantamine (Reminyl)
4. AntiParkinsonism Medications
  1. Levodopa-Carbidopa (Sinemet)
    1. Start with lowest dose of a single agent
    2. Goal: Improve mobility without inducing Psychosis
5. REM Sleep behavior disorder
  1. Clonazepam 0.25 to 1 mg orally at bedtime
6. Orthostatic Hypotension
  1. Fluids and increase sodium in diet
  2. Rise from lying or sitting slowly
  3. Avoid prolonged bed rest
7. Anti-psychotic medications (Neuroleptics)
  1. Cholinesterase inhibitors may reduce Psychosis
  2. High sensitivity to Neuroleptics in DLB
    1. May severely exacerbate Parkinsonism symptoms
      1. Rigidity
      2. Sedation
    2. Effects on Parkinsonism may be irreversible
    3. Effects may be life-threatening
      1. Example: Neuroleptic malignant syndrome
    4. Use Neuroleptics with caution and informed consent
  3. Agents
    1. Risperidone 0.25 mg PO bid (maximum 1 mg bid)
    2. Olanzapine 2.5 mg PO daily (maximum 10 mg daily)
    3. Quetiapine 25 mg PO bid (maximum 150 mg/day)
  4. Contraindicated agents: Older, type 2 Antipsychotics
    1. Avoid Haloperidol, fluphenazine, chlorpromazine
Resources
1. Lewy Body Dementia Association
  1. http://www.lewybodydisease.org/
References

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