Differential Diagnosis

The patient's presentation of altered mental status, visual hallucinations, and increased combativeness requires a thorough evaluation of potential causes. The differential diagnosis can be categorized as follows:

• Single most likely diagnosis
  • Delirium: The patient's recent history of urinary tract infection, episodes of hypomagnesemia, and changes in medication (antibiotics) are common precipitating factors for delirium, especially in elderly patients. The patient's symptoms of altered mental status, visual hallucinations, and fluctuating levels of consciousness are consistent with delirium.
• Other Likely diagnoses
  • Dementia with superimposed delirium: Although the patient has no known history of dementia, the recent onset of delirium and behavioral changes could be indicative of an underlying dementia process.
  • Medication-induced psychosis: The patient's recent change in antibiotics and potential interactions with other medications could contribute to medication-induced psychosis.
  • Electrolyte imbalance: The patient's history of hypomagnesemia and potential other electrolyte imbalances (e.g., hyponatremia, hypernatremia) could contribute to altered mental status and hallucinations.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Sepsis: The patient's recent urinary tract infection and altered mental status could be indicative of sepsis, which requires prompt recognition and treatment.
  • Stroke or transient ischemic attack (TIA): The patient's history of atrial fibrillation increases the risk of stroke or TIA, which could present with altered mental status and hallucinations.
  • Hypoxia: The patient's history of atrial fibrillation and potential for cardiac complications increases the risk of hypoxia, which could contribute to altered mental status.
  • Wernicke's encephalopathy: Although less common, Wernicke's encephalopathy is a potentially life-threatening condition that requires prompt recognition and treatment with thiamine supplementation.
• Rare diagnoses
  • Neurosyphilis: Although rare, neurosyphilis can present with altered mental status, hallucinations, and behavioral changes, especially in elderly patients.
  • Creutzfeldt-Jakob disease: This rare prion disease can present with rapidly progressive dementia, hallucinations, and altered mental status.

Orders for the Emergency Department

Based on the differential diagnosis, the following orders should be placed for the patient in the emergency department:

• Complete blood count (CBC) with differential
• Basic metabolic panel (BMP) with electrolytes
• Liver function tests (LFTs)
• Urinalysis with culture and sensitivity
• Blood cultures
• ECG
• Chest radiograph
• Non-contrast computed tomography (CT) of the head
• Thiamine supplementation (to cover for potential Wernicke's encephalopathy)
• Oxygen saturation monitoring and supplemental oxygen as needed
• Cardiac monitoring
• Neurological consultation for further evaluation and management
• Psychiatry consultation for evaluation and management of potential psychosis or delirium
• Consideration for lumbar puncture (LP) if neurosyphilis or other central nervous system infections are suspected.