Differential Diagnosis for 65 y/o Man with Delirium

Single Most Likely Diagnosis

• Acute Stroke (Left Hemisphere): The patient's presentation of delirium, fluent and nonsensical speech with no comprehension (indicative of Wernicke's aphasia), and decreased blink to visual threat in the right visual field suggests a left hemisphere stroke affecting areas responsible for language and possibly visual fields.

Other Likely Diagnoses

• Seizure or Post-Ictal State: The acute onset of delirium and nonsensical speech could be indicative of a seizure or a post-ictal state, especially if there's a history of seizure disorders.
• Toxic or Metabolic Encephalopathy: Various toxins or metabolic disturbances can cause delirium and altered mental status, which might also affect speech and comprehension.
• Infection (e.g., Meningitis, Encephalitis): Infections affecting the central nervous system can present with acute confusion, altered mental status, and focal neurological signs.

Do Not Miss Diagnoses

• Subdural Hematoma or Intracranial Hemorrhage: These conditions are medical emergencies that can present with altered mental status and focal neurological deficits. They require immediate diagnosis and treatment.
• Status Epilepticus: Although less likely given the description, status epilepticus can present with altered mental status and could be life-threatening if not promptly recognized and treated.
• Wernicke's Encephalopathy: This is a condition caused by thiamine deficiency, often seen in alcoholics, which can present with confusion, ophthalmoplegia, and ataxia. It's treatable but can have severe consequences if missed.

Rare Diagnoses

• Creutzfeldt-Jakob Disease: A rare, degenerative, fatal brain disorder that can present with rapidly progressive dementia, myoclonus, and various neurological signs.
• Hashimoto's Encephalopathy: A rare condition associated with Hashimoto's thyroiditis, presenting with encephalopathy, seizures, and stroke-like symptoms.
• CNS Vasculitis: Inflammation of the blood vessels in the brain, which can cause a wide range of neurological symptoms including stroke-like presentations, seizures, and encephalopathy.

Each of these diagnoses should be considered in the context of the patient's full medical history, physical examination, and appropriate diagnostic testing to determine the underlying cause of the patient's symptoms.