What is the most likely diagnosis for an elderly male patient with hypertension, managed with amlodipine, presenting with visual hallucinations, hypoglycemia, dysphagia, decreased sweating, and intact memory?

Lewy Body Dementia

The most likely diagnosis is B - Lewy body dementia, based on the pathognomonic combination of visual hallucinations with preserved memory, along with autonomic dysfunction (decreased sweating) and dysphagia. 1

Key Diagnostic Features Present

This patient demonstrates the classic triad that distinguishes Lewy body dementia from other dementias:

• Visual hallucinations with intact memory - This is the pathognomonic feature that differentiates Lewy body dementia from Alzheimer's disease, according to the American Academy of Neurology 1
• Autonomic dysfunction (decreased sweating) - This is characteristic of Lewy body dementia per the Alzheimer's Association 1
• Dysphagia - Another characteristic feature of Lewy body dementia 1

The American Geriatrics Society recommends considering Lewy body dementia specifically in patients presenting with fluctuating cognition, recurrent visual hallucinations, and spontaneous motor features including autonomic dysfunction and dysphagia 1. This patient meets these criteria precisely.

Why Other Diagnoses Are Excluded

Alzheimer's Dementia (Option A) - Ruled Out

• Memory impairment is the hallmark early feature of Alzheimer's disease, which this patient explicitly does not have 1
• Visual hallucinations are uncommon in pure Alzheimer's disease and typically occur only in advanced stages, not as a presenting feature 1
• The American Academy of Neurology confirms that preserved memory rules out Alzheimer's dementia 1

Multi-Infarct Dementia (Option C) - Ruled Out

• The American Heart Association notes that multi-infarct dementia typically presents with stepwise cognitive decline and focal neurological deficits, along with evidence of multiple strokes 1
• This patient lacks the vascular pattern of cognitive impairment 1
• No mention of stroke history or focal deficits in the presentation

Prion Disease (Option D) - Ruled Out

• The National Institute of Neurological Disorders and Stroke indicates that prion diseases present with very rapid cognitive decline, myoclonus, ataxia, and rapidly progressive dementia 1
• This patient's presentation lacks these characteristic features 1
• Prion disease would not explain the chronic presentation with preserved memory

Clinical Context and Pitfalls

Important consideration regarding hypoglycemia: While the Endocrine Society notes that hypoglycemia in elderly patients requires prompt evaluation and is associated with increased mortality, it does not explain the chronic neurological presentation 1. The hypoglycemia may be a concurrent acute event requiring separate management, but the constellation of visual hallucinations, autonomic dysfunction, dysphagia, and preserved memory points definitively to Lewy body dementia.

Regarding the amlodipine: This calcium channel blocker for hypertension management is actually associated with decreased dementia risk in patients over 60 years old 2, so it is not contributing to the neurological symptoms.

Critical clinical pearl: The American Academy of Neurology emphasizes that the presence of neurological signs (dysphagia and autonomic dysfunction) alongside visual hallucinations mandates consideration of Lewy body dementia or Parkinson's disease with dementia rather than other conditions 1. The preserved memory is the key distinguishing feature that makes this diagnosis certain.

Lewy body dementia is the second most common form of degenerative dementia, accounting for up to 20% of cases in the elderly 3, and is characterized by fluctuating cognitive impairment, spontaneous parkinsonism, and recurrent visual hallucinations 3.