A 66-year-old woman is brought to the emergency department by her son due to increasing confusion, loss of mobility, and behavioral changes. The patient cries out for no apparent reason and recently exclaimed that "a lion was sleeping in the backyard." She often sees cats in her room when none are present. She has had memory loss and frequently gets lost in her neighborhood. The patient is afebrile; blood pressure is 136/72 mm Hg, pulse is 98/min, and respirations are 16/min. On physical examination, she is alert but disoriented and quite agitated. Physical examination shows increased muscle tone, normal reflexes, and coarse resting tremors in the extremities. Which of the following is most closely associated with this patient's current condition?
Differential diagnosis of dementia subtypes | |
Alzheimer |
|
Vascular |
|
Frontotemporal dementia |
|
Dementia with Lewy bodies |
|
Normal pressure hydrocephalus |
|
Prion disease |
|
This patient's confusion, memory loss, prominent visual hallucinations, and parkinsonian motor symptoms (ie, increased muscle tone, coarse resting tremor) are consistent with dementia with Lewy bodies (DLB), a form of degenerative dementia characterized by eosinophilic cytoplasmic inclusions of alpha-synuclein (Lewy bodies) in the brain. Core clinical features of DLB include fluctuating cognition with pronounced variations in attention, detailed visual hallucinations, REM sleep behavior disorder, and parkinsonism.
Severe sensitivity to antipsychotics (dopamine antagonists) is commonly seen in patients with DLB and is considered a supportive clinical feature. Adverse effects to antipsychotics are not dose related and include worsening of parkinsonian symptoms, confusion, and autonomic dysfunction. Reactions are more common with high-potency first-generation antipsychotics (eg, haloperidol) but may also be seen with second-generation antipsychotics. Other supportive clinical features of DLB include repeated falls, syncope, autonomic dysfunction, delusions, and depression.
(Choice A) The presence of concurrent atherosclerotic cardiovascular disease would be associated with vascular dementia. Vascular dementia is due to large artery (usually cortical) or smaller artery (subcortical or lacunar) infarctions and is typically associated with focal neurologic findings specific to the infarct location.
(Choice C) Autonomic dysfunction (eg orthostatic hypotension, heart rate variability), not respiratory muscle weakness, is a common feature in DLB. Respiratory muscle weakness is a classic feature of amyotrophic lateral sclerosis, characterized by progressive muscular weakness with upper and lower motor neuron involvement.
(Choice D) Predominant atrophy of frontotemporal lobes is seen in frontotemporal dementia, which is characterized by early personality changes (eg, disinhibition, apathy), compulsive behaviors (eg, peculiar eating habits, hyperorality), and impaired memory. Visual-spatial functions usually remain intact.
(Choice E) Rapid response to high-volume lumbar puncture is a confirmatory test for normal-pressure hydrocephalus (NPH) in which gait function typically improves following removal of 30-50 mL of cerebrospinal fluid. NPH presents with the triad of cognitive impairment, gait disturbance, and urinary incontinence.
(Choice F) Vertical supranuclear palsy (ie, inability to elevate eye to look up) is a feature of progressive supranuclear palsy (PSP), which presents with dementia, postural instability, vertical supranuclear palsy, and parkinsonism. Hallucinations are not a feature of PSP.
Educational objective:
Dementia with Lewy bodies is characterized by fluctuating cognitive impairment, recurrent visual hallucinations, REM sleep behavior disorder, and parkinsonism. Severe sensitivity to antipsychotics (dopamine antagonists) is a supportive clinical feature.