Differential Diagnosis for Intermittent Confusion

Single Most Likely Diagnosis

• Delirium: This is often the first consideration for new-onset confusion, especially if it's intermittent. Delirium can be caused by a variety of factors including infections, medications, or changes in environment, making it a broad and likely diagnosis for someone presenting with confusion that is not their baseline.

Other Likely Diagnoses

• Dementia with fluctuating course: Conditions like Lewy Body Dementia can present with fluctuating cognitive function, which might be perceived as intermittent confusion.
• Seizures: Certain types of seizures, especially complex partial seizures, can present with confusion or altered mental status before, during, or after the seizure.
• Metabolic Disorders: Electrolyte imbalances, hypoglycemia, or hyperglycemia can cause confusion. These conditions are relatively common and can fluctuate, leading to intermittent symptoms.
• Medication Side Effects: Many medications, especially those with anticholinergic properties, can cause confusion as a side effect. The effect can be intermittent, depending on the timing of medication administration and the individual's sensitivity.

Do Not Miss Diagnoses

• Intracranial Hemorrhage or Stroke: Although less common, these conditions are medical emergencies that can present with sudden onset of confusion. Missing these diagnoses can be catastrophic.
• Meningitis or Encephalitis: Infections of the brain or meninges can cause confusion, fever, and other neurological symptoms. Prompt diagnosis and treatment are crucial.
• Hypoxia: Low oxygen levels, from any cause (e.g., pulmonary embolism, heart failure), can lead to confusion. Identifying and treating the underlying cause is critical.

Rare Diagnoses

• Creutzfeldt-Jakob Disease: A rare, degenerative, fatal brain disorder that can cause rapid dementia and fluctuating cognitive function.
• Hashimoto's Encephalopathy: A rare condition associated with Hashimoto's thyroiditis, characterized by cognitive impairment, seizures, and myoclonus.
• Whipple's Disease: A rare, systemic bacterial infection that can cause neurological symptoms, including dementia and confusion, among other systemic symptoms.

Each of these diagnoses has a different set of implications for treatment and prognosis, highlighting the importance of a thorough diagnostic evaluation for someone presenting with new-onset intermittent confusion.