Differential Diagnosis for 100 y/o with Hallucinations and Normal Labs

Single Most Likely Diagnosis

• Dementia with Lewy Bodies: This condition is a common cause of hallucinations in the elderly, especially in those with a history of cognitive decline. The normal lab results do not rule out this diagnosis, as it is primarily clinical.

Other Likely Diagnoses

• Alzheimer's Disease with Psychotic Symptoms: While less common than dementia with Lewy bodies for causing hallucinations, Alzheimer's disease can also present with psychotic symptoms, including hallucinations, especially in advanced stages.
• Delirium: Although the question does not provide information on the acute onset of symptoms or fluctuating course, delirium is a common condition in the elderly that can cause hallucinations. Normal labs would not rule out delirium, as it is often caused by underlying medical conditions or medications.
• Charles Bonnet Syndrome: This condition occurs in visually impaired individuals and can cause complex visual hallucinations. Given the age of the patient, visual impairment is a plausible comorbidity.

Do Not Miss Diagnoses

• Neurosyphilis: Although rare, neurosyphilis can cause hallucinations among other neurological symptoms. It is crucial to consider and rule out this condition due to its treatability and potential for severe consequences if left untreated.
• Vitamin B12 Deficiency: While the labs are reported as "wnl" (within normal limits), it's essential to ensure that a vitamin B12 level was specifically checked, as deficiency can cause neurological and psychiatric symptoms, including hallucinations.
• Medication-Induced Hallucinations: Many medications, especially those with anticholinergic properties, can cause hallucinations in the elderly. A thorough medication review is necessary to rule out this potentially reversible cause.

Rare Diagnoses

• Prion Diseases (e.g., Creutzfeldt-Jakob Disease): These are rare, degenerative, and fatal brain disorders that can cause hallucinations among other symptoms. They are essential to consider due to their severity, although they are much less common.
• Temporal Lobe Seizures: Seizure activity, particularly from the temporal lobe, can cause hallucinations. This would be an unusual presentation in a 100-year-old without a history of seizures but should be considered if other explanations are exhausted.