What Is Lightheadedness? (Presyncope)?

Lightheadedness is a feeling of faintness or wooziness, as if you are suddenly about to pass out. You may feel nauseous, sweaty, and even have trouble hearing or seeing well. The severity of an episode can range from mild to debilitating.

It's other name, presyncope, means "before fainting." However, presyncope can also happen on its own. It also can occur once, in episodes, or be persistent.

Presyncope is often related to conditions that affect the heart or blood circulation. However, other conditions can cause lightheadedness as well.

This article discusses the symptoms and causes of lightheadedness and how the condition is diagnosed and treated.

Symptoms

By definition, presyncope must involve the sensation of nearly fainting. People with presyncope will typically say that they feel as if they are "about to pass out" or "about to black out."

The symptoms and signs of presyncope may involve some or all of the following:

• Dizziness
• Confusion (often described as "suddenly not knowing where I was")
• Blurry vision
• Trouble hearing
• Nausea or vomiting
• Sweating
• Heart palpitations
• Slurring of speech

If the lightheadedness is caused by a heart condition, there may be other signs like chest pains or shortness of breath.

Chronic presyncope can significantly impair a person's well-being and quality of life.

Causes

There are many potential causes of lightheadedness. Most causes are typically harmless, while some may be severe and even life-threatening.

Strictly speaking, presyncope can be broadly categorized as either cardiac (related to the heart) or non-cardiac (not related to the heart). Non-cardiac causes are more common and often less severe than cardiac causes.

These are just some of the more common cardiac and non-cardiac causes of presyncope:

Cardiac Presyncope Causes

• Aortic stenosis, a narrowing of the aortic valve opening
• Bradycardia, a slow heart rate
• Cardiac tamponade, a buildup of blood or fluid in the sac surrounding the heart
• Heart failure
• Heart valve disease
• Hypertrophic cardiomyopathy, a thickening of the heart muscle
• Orthostatic hypotension, low blood pressure that occurs when standing up from a sitting or lying position
• Silent heart attack
• Ventricular tachycardia, a rapid heart rate

Non-cardiac Presyncope Causes

• Acute hypotension, a sudden drop in blood pressure
• Anaphylaxis, a life-threatening allergic reaction
• Dehydration
• Dysautonomia, conditions caused by a malfunctioning autonomic nervous system
• Head trauma
• Hypoglycemia, a condition caused by low glucose levels (ie., low blood sugar)
• Medications
• Neurogenic orthostatic hypotension, a form of orthostatic hypotension caused by a malfunctioning autonomic nervous system
• Vasovagal episodes​, fainting caused by certain triggers
  

Diagnosis

Lightheadedness should never be ignored, particularly if it is severe, recurrent, or chronic.

Your healthcare provider will need to conduct a careful evaluation to figure out which of the many possible causes is to blame for how you feel.

This typically starts with a physical exam to check your vital signs (e.g., blood pressure and heart rate) and a review of medical history, including any medications you take and conditions you have/have had.

After a review of your symptoms, testing can be considered.

Symptom Review

Your provider will likely ask you to be very specific when describing your symptoms.

Among the reasons why, lightheadedness is an imprecise term. Some may use it to describe sensations that are similar, but that do not involve a sense of impending fainting.

Among them:

• Vertigo is a sensation of motion when there is no motion. People will often describe it as a whirling sensation or say that the "room is spinning."
• Disequilibrium is a sense of imbalance or unsteadiness. Depending on the cause, it may also occur with lightheadedness.

They will want to know:

• The circumstances under which your lightheadedness occurs
• How quickly it sets in and lasts
• How often it happens

They will also ask about other symptoms you may be experiencing, such as fatigue. Mention anything you can think of, even if you don't think it's related.

This information, plus what they know about your health history, can help your provider narrow down some possibilities for further investigation.

For example:

• Cardiac presyncope tends to come on relatively quickly, usually within five seconds.
• Presnycope caused by orthostatic hypotension, which is when your blood pressure quickly drops when you stand up, tends to be recurrent. It is also more common in people with diabetes and Parkinson's disease.
• Vasovagal presyncope episodes (presyncope caused by a drop in blood pressure) tends to have an underlying factor like sleep deprivation or extreme emotions. They occur for longer than five seconds.

Blood Tests

Based on the initial findings, your healthcare provider may order a variety of lab tests to check for or exclude possible causes. These may include:

• Blood glucose test to help detect diabetes
• Complete blood count (CBC) to detect anemia or other blood irregularities
• Cardiac enzymes that can help diagnose a silent heart attack
• Blood electrolytes to help detect dehydration

Imaging and Other Tests

Imaging studies and procedures may also be ordered based on your symptoms and risk factors.

• Head computed tomography (CT), imaging that checks for head trauma
• Electrocardiogram (ECG), a test to evaluate heart function
• Echocardiogram, a form of ultrasound that provides a real-time look at the heart structure and function
• Tilt table test, which involves creating changes in posture to check for a drop in blood pressure caused by standing up after sitting or lying down

Other tests may be ordered as the possible causes are whittled down.

Treatment

The treatment of lightheadedness depends on the underlying cause. There are many possibilities.

For most people who experience lightheadedness, in which dehydration or vasovagal episodes are common causes, the treatment will consist mainly of learning to avoid situations that can trigger symptoms.

If lightheadedness is related to an undiagnosed cardiovascular condition, you may be referred to a cardiologist for further evaluation and treatment. Other causes may require specialists as far-ranging as allergists, endocrinologists, and neurologists.

Summary

Many often describe presyncope or lightheadedness as a feeling of impending loss of consciousness; in other words, they may feel as if they are about to "pass out." Symptoms can include dizziness, nausea, blurry vision, and confusion.

Non-cardiac related causes, such as dehydration, are more common and usually less severe than cardiac-related ones.

Treatment depends on what the underlying cause of the condition is. Treating the underlying issue will typically resolve lightheadedness.