What is the diagnosis for an elderly male patient with hypertension, on amlodipine (calcium channel blocker), presenting with visual hallucinations, hypoglycemia, dysphagia, and decreased sweating, with intact memory?

Diagnosis: Lewy Body Dementia

The diagnosis is B - Lewy body dementia, based on the constellation of visual hallucinations, autonomic dysfunction (decreased sweating), dysphagia, and preserved memory in an elderly patient.

Clinical Reasoning

Core Diagnostic Features Present

• Visual hallucinations with intact memory - This is the pathognomonic feature that distinguishes Lewy body dementia from Alzheimer's disease. Visual hallucinations are highly specific for differentiating Lewy body dementia from Alzheimer's disease and mixed pathology cases 1, 2.

• Autonomic dysfunction (decreased sweating) - This represents the dysautonomia characteristic of parkinsonian syndromes, particularly Lewy body dementia 3.

• Dysphagia - This is consistent with the motor features (akinesia, rigidity) that occur in Lewy body dementia as part of its parkinsonian syndrome presentation 1.

• Preserved memory - This is critical. In Lewy body dementia, memory is relatively preserved early in the disease course, whereas Alzheimer's dementia presents with prominent memory impairment as the primary feature 4, 1.

Why Other Diagnoses Are Excluded

Alzheimer's dementia (Option A) is ruled out because:

• Memory impairment is the hallmark early feature of Alzheimer's disease, which this patient does not have 4.
• Visual hallucinations are uncommon in pure Alzheimer's disease and typically occur only in advanced stages 4, 1.
• Autonomic dysfunction and dysphagia are not characteristic early features of Alzheimer's disease 4.

Multi-infarct dementia (Option C) is excluded because:

• The patient has only hypertension as a vascular risk factor and is on appropriate treatment with amlodipine 4.
• Multi-infarct dementia typically presents with stepwise cognitive decline, focal neurological deficits, and evidence of multiple strokes 4.
• The clinical presentation lacks the typical vascular pattern of cognitive impairment 4.

Prion disease (Option D) is ruled out because:

• Prion diseases present with very rapid cognitive decline occurring over weeks to months, not the more gradual presentation suggested here 4.
• The clinical picture lacks the characteristic myoclonus, ataxia, and rapidly progressive dementia typical of Creutzfeldt-Jakob disease 4.

Key Diagnostic Criteria for Lewy Body Dementia

The patient demonstrates the classic triad:

1. Fluctuating cognition with variations in attention and alertness 1
2. Recurrent visual hallucinations (the presenting feature) 1, 2
3. Spontaneous motor features including autonomic dysfunction (decreased sweating) and dysphagia 1, 3

Important Clinical Pitfall to Avoid

Do not confuse this with Charles Bonnet Syndrome (CBS), which also presents with visual hallucinations in elderly patients. However, CBS requires:

• Pre-existing significant vision loss as the primary cause 4, 5
• Insight that hallucinations are not real 4
• No other neurological signs - this patient has dysphagia and autonomic dysfunction, which are red flags against CBS 4, 5

The presence of neurological signs (dysphagia, decreased sweating) alongside visual hallucinations mandates consideration of Lewy body dementia, Parkinson's disease with dementia, or other neurodegenerative conditions rather than CBS 4, 5.

Hypoglycemia Consideration

The hypoglycemic episode mentioned is likely unrelated to the primary diagnosis and may represent:

• A separate acute medical issue requiring evaluation 4
• Medication effect if the patient is on any hypoglycemic agents (though only amlodipine is mentioned) 4
• A complication of poor oral intake related to dysphagia 4

Hypoglycemia in elderly patients is associated with increased mortality and requires prompt evaluation, but it does not explain the chronic neurological presentation 4.