Neurology · Year 3 · from Neurology

Case 2: Lewy Body Dementia

Patient Demographics

  • Age: 74 years
  • Sex: Male
  • Occupation: Retired electrician

Chief Complaint

"He sees children in the room who aren't there, and some days he's fine, other days he's very confused."

History of Present Illness

The patient's wife reports that over the past 18 months, he has experienced episodes of confusion with marked day-to-day (and even hour-to-hour) fluctuation. Some mornings he is nearly normal; other times he is extremely confused and somnolent. He has been seeing "little children playing in the living room" - visual hallucinations that are vivid, detailed, and non-threatening. He knows they are not real but still sees them. He has developed a shuffling gait and moves slowly. He acts out his dreams - shouting, punching, and kicking during sleep (REM sleep behavior disorder). His wife reports he has had two falls. He was recently started on haloperidol for agitation at an urgent care, which made him severely rigid and nearly unresponsive (neuroleptic sensitivity).

Neurological Examination Findings

Mental Status:

  • Fluctuating attention - alert during exam but wife reports prolonged staring spells
  • MMSE: 20/30 (impaired attention and visuospatial)
  • Clock drawing: Severely impaired
  • Recall: 2/3 (better than expected for dementia)
  • Detailed visual hallucinations reported

Cranial Nerves:

  • Hypomimia (masked facies)
  • Reduced blink rate
  • Mild hypophonia

Motor Examination:

  • Parkinsonian features:
  • Bilateral bradykinesia (slow finger taps)
  • Cogwheel rigidity at wrists and elbows
  • Mild rest tremor (less prominent than idiopathic PD)
  • Strength: 5/5

Sensory Examination:

  • Intact

Reflexes:

  • 2+ symmetric
  • No frontal release signs

Coordination:

  • Slowed movements

Gait:

  • Short, shuffling steps
  • Reduced arm swing
  • Stooped posture
  • Postural instability (positive pull test)

Diagnostic Criteria

Revised Criteria for Dementia with Lewy Bodies (McKeith 2017):

  • Essential: Dementia with progressive cognitive decline
  • Core Features (≥2 = probable DLB):
  1. ✓ Fluctuating cognition with pronounced variations in attention/alertness
  2. ✓ Recurrent visual hallucinations (typically well-formed, detailed)
  3. ✓ REM sleep behavior disorder
  4. ✓ Parkinsonism
  • Supportive features: Severe neuroleptic sensitivity, postural instability, falls, autonomic dysfunction, depression

This patient has all 4 core features = Probable DLB

Neuro Workup

  • MRI Brain:
  • Mild generalized atrophy
  • Relative preservation of hippocampi (unlike AD)
  • No significant vascular disease
  • DaTscan (dopamine transporter SPECT):
  • Reduced dopaminergic uptake in basal ganglia bilaterally (supportive biomarker)
  • Helps differentiate DLB from AD
  • Polysomnography:
  • REM sleep without atonia
  • Dream enactment behavior
  • FDG-PET:
  • Posterior cortical hypometabolism with occipital involvement ("cingulate island sign")
  • EEG:
  • Posterior slowing with fluctuations

Diagnosis

Probable Dementia with Lewy Bodies (DLB)

Management

Cognitive Symptoms:

  1. Cholinesterase inhibitor: Rivastigmine 1.5 mg BID, titrate up
  • DLB patients often have more cholinergic deficit
  • May also improve hallucinations
  1. Memantine: Can be added

Visual Hallucinations:

  1. If non-distressing: Reassurance, no treatment needed
  2. If distressing: Low-dose quetiapine 12.5-25 mg (least D2 blocking)
  3. Pimavanserin (selective 5-HT2A inverse agonist) - approved for PD psychosis
  4. AVOID: Haloperidol, risperidone, olanzapine - neuroleptic sensitivity can be fatal

Parkinsonian Symptoms:

  1. Carbidopa/levodopa 25/100 TID - careful, lower doses
  • May worsen hallucinations
  • Start low, go slow
  1. Avoid anticholinergics for PD (worsen cognition)
  2. Physical therapy for gait and balance

REM Sleep Behavior Disorder:

  1. Melatonin 3-12 mg at bedtime (first-line)
  2. Clonazepam 0.25-0.5 mg at bedtime (second-line)
  3. Bed safety measures (remove sharp objects, pad bed rails)

Autonomic Dysfunction:

  1. Orthostatic hypotension: Compression stockings, midodrine, fludrocortisone
  2. Constipation: Fiber, PEG

Safety:

  1. Fall prevention (PT, home safety)
  2. Driving cessation (hallucinations + parkinsonism)
  3. Supervision during fluctuating episodes

Caregiver Education:

  1. Expect fluctuations - good days and bad days
  2. Do not argue about hallucinations
  3. Watch for neuroleptic sensitivity if hospitalized
  4. Medical alert bracelet indicating medication sensitivities

Clinical Image

Image Description: DaTscan showing reduced dopamine transporter uptake in the bilateral striatum, a supportive biomarker for dementia with Lewy bodies.

Attribution: Image from Radiopaedia.org, Case courtesy of Dr. Ian Bickle. Licensed under CC BY-NC-SA 3.0. Source: https://radiopaedia.org/cases/dementia-with-lewy-bodies-2

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