What could be the cause of dizziness and palpitations in a 39-year-old female with no neurological signs?

Differential Diagnosis: Dizziness with Palpitations in a 39-Year-Old Female

In a 39-year-old female presenting with 3 days of dizziness and palpitations without neurological signs, the most likely diagnoses are cardiac arrhythmia (particularly supraventricular tachycardia), orthostatic intolerance syndromes, or reflex syncope—all of which require immediate cardiac evaluation before considering vestibular causes.

Primary Diagnostic Considerations

Cardiac Arrhythmia (Most Critical to Exclude First)

Arrhythmias are the most common cardiac causes of syncope and dizziness, inducing hemodynamic impairment that causes critical decreases in cardiac output and cerebral blood flow 1.

• Supraventricular tachycardia (SVT), particularly AVNRT, is the most common SVT and occurs predominantly in women (>60% of cases), typically presenting with sudden onset palpitations, dizziness, and shortness of breath 1.
• The ventricular rate in AVNRT ranges from 110-250 bpm, and patients are usually young adults without structural heart disease 1.
• Palpitations with dizziness lasting 3 days suggests either recurrent paroxysmal episodes or sustained arrhythmia requiring urgent ECG evaluation 1.
• Electrolyte abnormalities, particularly severe hypocalcemia and hypomagnesemia, can precipitate ventricular tachycardia presenting with dizziness, palpitations, and hypotension 2.

Orthostatic Intolerance Syndromes

Orthostatic intolerance refers to symptoms in the upright position due to circulatory abnormality, with dizziness, palpitations, and sweating being cardinal features 1.

• Classical orthostatic hypotension presents with dizziness, pre-syncope, fatigue, weakness, palpitations, and visual/hearing disturbances occurring 30 seconds to 3 minutes after standing 1.
• Postural Orthostatic Tachycardia Syndrome (POTS) occurs predominantly in young females, causing symptomatic marked heart rate increases with blood pressure instability but typically without syncope 1.
• Drug-induced orthostatic hypotension from vasoactive medications or diuretics is common in this age group 1.

Reflex Syncope (Vasovagal)

• Reflex syncope triggered by standing occurs predominantly in young healthy females, with clear prodrome including dizziness and palpitations, typically occurring 3-45 minutes after standing 1.
• The initial normal adaptation reflex is followed by rapid fall in venous return and vasovagal reaction 1.

Essential Immediate Evaluation

Cardiac Assessment (First Priority)

• Obtain 12-lead ECG immediately to identify arrhythmias, conduction abnormalities, or QT prolongation 1.
• Check orthostatic vital signs (lying, sitting, standing at 1 and 3 minutes) to identify orthostatic hypotension or POTS 1.
• If palpitations are ongoing or recurrent, consider continuous cardiac monitoring or event recorder 1.
• Obtain basic metabolic panel including calcium and magnesium, as severe electrolyte abnormalities can cause arrhythmias with these exact symptoms 2.

Exclude Central Causes (Red Flags)

The absence of neurological signs is reassuring, but specific red flags must be actively excluded 1, 3:

• New-onset severe headache with dizziness requires immediate vascular assessment 1, 4.
• Any limb weakness, visual changes, dysarthria, dysphagia, or severe postural instability demands urgent neuroimaging 1, 4, 3.
• Baseline nystagmus without provocative maneuvers, pure vertical nystagmus, or direction-changing nystagmus suggests central pathology 3.

Diagnostic Algorithm

Step 1: Cardiac Evaluation

• ECG and orthostatic vital signs immediately
• If arrhythmia detected: treat per ACLS/arrhythmia protocols 1
• If orthostatic hypotension confirmed: evaluate for volume depletion, medications, autonomic dysfunction 1

Step 2: Timing and Trigger Assessment

• Episodes lasting seconds to minutes triggered by position changes suggest BPPV or orthostatic causes 3
• Continuous symptoms lasting days suggest vestibular neuritis, labyrinthitis, or sustained arrhythmia 3
• Spontaneous episodes lasting minutes to hours without triggers suggest vestibular migraine, Ménière's disease, or paroxysmal arrhythmia 3

Step 3: Vestibular Examination (Only After Cardiac Causes Excluded)

• Perform Dix-Hallpike maneuver if episodic positional symptoms present 3
• Assess for nystagmus characteristics to differentiate peripheral from central causes 3
• Do NOT pursue vestibular testing if cardiac arrhythmia is suspected or confirmed 3

Critical Pitfalls to Avoid

• Never attribute palpitations with dizziness to "just anxiety" without excluding cardiac arrhythmia first—arrhythmias are the most common cardiac cause of these symptoms 1.
• Do not assume absence of neurological signs excludes serious pathology—approximately 25% of patients with acute vestibular syndrome have cerebrovascular disease 3.
• Avoid missing medication-induced causes—review all medications including over-the-counter drugs, as many cause orthostatic hypotension or arrhythmias 1.
• Do not overlook electrolyte abnormalities—severe hypocalcemia can cause refractory ventricular tachycardia presenting exactly with these symptoms 2.
• Recognize that multiple concurrent conditions may coexist—a patient can have both BPPV and cardiac arrhythmia simultaneously 3.

When to Image

• Neuroimaging is NOT indicated for isolated dizziness with palpitations and no neurological signs, unless red flags are present 1.
• The positivity rate of head CT in emergency department patients with isolated dizziness is only approximately 2% 1.
• MRI with DWI is indicated if any neurological symptoms develop, severe postural instability occurs, or symptoms fail to respond to appropriate treatment 1, 3.