Differential Diagnosis for Sudden Onset Dizziness and Pre-Syncope in an 85-Year-Old Female

Single Most Likely Diagnosis

• Vasovagal Syncope: Given the sudden onset of dizziness, lightheadedness, hot flashes, pre-syncope, and palpitations, especially in an elderly patient with a history of CHF and hypertension, vasovagal syncope is a strong consideration. The brief duration and occurrence of symptoms in close succession also support this diagnosis.

Other Likely Diagnoses

• Orthostatic Hypotension: This condition is common in the elderly and can be exacerbated by CHF and hypertension medications, leading to sudden drops in blood pressure upon standing, resulting in dizziness and pre-syncope.
• Cardiac Arrhythmias: Given the patient's history of CHF and hypertension, arrhythmias such as atrial fibrillation or ventricular tachycardia could lead to palpitations and pre-syncope.
• Dehydration: Elderly individuals are more susceptible to dehydration, which can cause dizziness, lightheadedness, and pre-syncope, especially if they have been experiencing decreased fluid intake or increased fluid loss.

Do Not Miss Diagnoses

• Myocardial Infarction (MI) or Acute Coronary Syndrome (ACS): Although less likely given the brief duration and specific symptoms, MI or ACS must be considered, especially in a patient with a history of CHF and hypertension, as these conditions can present atypically in the elderly.
• Pulmonary Embolism (PE): Sudden onset of dizziness and pre-syncope, even without typical symptoms like chest pain or shortness of breath, warrants consideration of PE due to its high mortality rate if missed.
• Stroke or Transient Ischemic Attack (TIA): While the symptoms do not classically suggest a stroke, the sudden onset of dizziness could be a manifestation of a vertebral-basilar insufficiency or TIA, which would be critical to diagnose promptly.

Rare Diagnoses

• Pheochromocytoma: A rare tumor of the adrenal gland that can cause episodic hypertension, palpitations, and sweating, which might be considered if other diagnoses are ruled out and symptoms persist or recur.
• Subclavian Steal Syndrome: A rare condition where there is a significant stenosis or occlusion of the subclavian artery, leading to vertebral-basilar insufficiency and symptoms like dizziness upon arm exercise, which is less likely but could be considered in the absence of other explanations.