What causes lightheadedness?

Causes of Lightheadedness

Lightheadedness is most commonly caused by orthostatic hypotension, vasovagal (reflex) syncope, cardiac arrhythmias, vestibular disorders, medications, or psychiatric conditions, with the specific etiology determined by timing, triggers, and associated symptoms. 1

Cardiovascular Causes

Orthostatic Hypotension

• Defined as a drop in systolic BP ≥20 mmHg or diastolic BP ≥10 mmHg within 3 minutes of standing, causing symptoms of lightheadedness, dizziness, visual disturbances, weakness, and near-syncope 1
• Initial orthostatic hypotension occurs within 15 seconds of standing with rapid BP recovery, causing brief but potentially severe symptoms 1
• Delayed orthostatic hypotension develops beyond 3 minutes of standing with gradual BP decline, more common in elderly patients 1
• Neurogenic orthostatic hypotension results from autonomic nervous system dysfunction (Parkinson's disease, multiple system atrophy, diabetic neuropathy, pure autonomic failure) with characteristically blunted heart rate response (<10 bpm increase) 1, 2
• Non-neurogenic causes include volume depletion, medications (antihypertensives, diuretics, vasodilators), and deconditioning 1

Reflex (Vasovagal) Syncope

• Characterized by BP drop starting several minutes after standing with accelerating decline until syncope occurs, distinguished from orthostatic hypotension by the delayed onset and rapid progression 1
• Associated with autonomic activation symptoms: pallor, sweating, nausea 1
• Triggered by prolonged standing, emotional stress, pain, or specific situations 1
• Patients with vasovagal syncope are at low risk for adverse outcomes 1

Cardiac Arrhythmias

• Bradyarrhythmias (sick sinus syndrome, AV block) and tachyarrhythmias (supraventricular or ventricular) cause lightheadedness through reduced cardiac output and cerebral hypoperfusion 1
• Palpitations preceding lightheadedness suggest arrhythmic etiology 1
• Patients >60 years with known cardiovascular disease are at high risk for adverse outcomes and require cardiac evaluation 1

Structural Cardiac Disease

• Aortic stenosis, hypertrophic cardiomyopathy, and heart failure cause lightheadedness through outflow obstruction or reduced cardiac output 1
• Physical examination findings of heart failure indicate high risk of sudden death 1

Vestibular and Neurological Causes

Postural Orthostatic Tachycardia Syndrome (POTS)

• Sustained heart rate increase ≥30 bpm (or ≥40 bpm in ages 12-19) within 10 minutes of standing without orthostatic hypotension, causing severe lightheadedness, palpitations, tremor, weakness, blurred vision, and fatigue 1
• Predominantly affects young women, often associated with deconditioning, recent infections, chronic fatigue syndrome, and joint hypermobility 1

Benign Paroxysmal Positional Vertigo (BPPV)

• While primarily causing vertigo, BPPV can present with lightheadedness triggered by specific head position changes 1
• Distinguished by positive Dix-Hallpike maneuver 1

Vertebrobasilar Insufficiency

• Episodes typically last <30 minutes without hearing loss, with gaze-evoked nystagmus that doesn't fatigue 1
• Requires differentiation from peripheral vestibular causes through neurological examination 1

Medication-Related Causes

Antihypertensive agents, cardiovascular drugs, diuretics, and CNS medications are the most frequently cited causes of lightheadedness, particularly in elderly patients taking multiple medications 1

• Drugs prolonging QT interval can cause life-threatening arrhythmias 1
• Vasodilators used for angina commonly cause lightheadedness 1
• Medications including carbamazepine, phenytoin, and Mysoline produce dizziness/lightheadedness as side effects 1

Psychiatric and Other Causes

Psychiatric Disorders

• Panic disorder, anxiety disorder, and agoraphobia cause lightheadedness symptoms, traditionally attributed to hyperventilation, though vestibular dysfunction is also prevalent in these patients 1
• Hyperventilation syndrome produces vague lightheadedness 3

Metabolic and Systemic Causes

• Hypoglycemia, dehydration, and metabolic disturbances cause lightheadedness through mechanisms distinct from cerebral hypoperfusion 1
• These are often diagnosed clinically without requiring neuroimaging 1

Clinical Approach

Key Historical Features

The timing and triggers of lightheadedness are more clinically useful than quality descriptors 4:

• Symptoms upon standing suggest orthostatic hypotension or POTS 1
• Symptoms relieved by sitting/lying indicate orthostatic intolerance 1
• Symptoms worse in morning, with heat, after meals, or with exertion suggest autonomic dysfunction 1
• Recurrence of symptoms on standing is more significant than numeric BP changes 1

Physical Examination Priorities

• Orthostatic vital signs: Measure BP and heart rate after 5 minutes supine and at 3 minutes standing 5
• Cardiac examination for murmurs, heart failure signs 1
• Neurological examination to exclude central causes 1
• Assessment for nystagmus and Dix-Hallpike maneuver if vertigo component present 3, 4

Common Pitfalls

• Orthostatic hypotension is present in up to 40% of asymptomatic patients >70 years, so correlation with symptoms is essential 1
• Imaging has extremely low yield (<1% for CT, 4% for MRI) in isolated lightheadedness without neurological deficits and should not be routinely performed 1
• Multiple conditions can coexist, particularly in elderly patients 1
• Up to 20% of cases remain undiagnosed despite thorough evaluation 3