What Is Presyncope (Lightheadedness)?

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Lightheadedness is a feeling of faintness or wooziness, as if you are suddenly about to black out. Another term for lightheadedness is presyncope (as opposed to syncope, which means fainting).

A man feeling lightheaded with his eyes closed and fingers to his brow
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Lightheadedness can occur in isolation, in episodes, or be persistent. Presyncope is often related to conditions that affect the heart or blood circulation, causing lightheadedness while you are in an upright position or suddenly rising. Other conditions not related to the heart can also cause presyncope.

The severity of presyncope can range from mild to debilitating. Chronic presyncope can significantly impair a person's well-being and quality of life.

Types

Lightheadedness is one type of dizziness. When people tell their doctor they have lightheadedness, they can actually mean several things. Presyncope is only one of them.

Presycnope is defined as the sensation of an impending loss of consciousness. People with presyncope will typically say that they feel as if they were "about to pass out" or "about to black out."

Because "lightheadedness" is an imprecise term, it can be used to describe similar conditions in which there may or may not be any sense of impending fainting. Among them:

  • Vertigo is s 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 that usually occurs when walking. Depending on the cause, it may also occur with lightheadedness.

Symptoms

By definition, presyncope must involve the sensation of nearly fainting. Even so, the sensation of fainting is largely subjective, and people will sometimes say that they were "about to faint" simply to describe how profound or emotional an experience was to them.

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

  • Dizziness
  • Confusion (often described as "suddenly not knowing where I was")
  • Blurry vision or tunnel vision
  • Changes in hearing (often described as a dulling of sounds or a sudden buzzing or ringing sound)
  • Nausea or vomiting
  • Sweating
  • Heart palpitations
  • Slurring of speech

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

Causes

Because there is a significant overlap between presyncope, vertigo, and disequilibrium, the causes of lightheadedness can be many. Some are benign; others may be severe and even potentially life-threatening.

Strictly speaking, presyncope can be broadly categorized as either cardiac (related to the heart) and non-cardiac (not related to the heart).

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

Diagnosis

Because lightheadedness has so many possible causes, your doctor will need to conduct a careful evaluation. This typically starts with a physical exam to check your vital signs (including your blood pressure and heart rate) and a review of your symptoms and medical history (including any medications you take).

Based on the initial evaluation, the doctor may have a better understanding of where to focus the investigation. For example:

  • Cardiac presyncope tends to come on relatively quickly, usually within five seconds.
  • Orthostatic hypotension tends to be recurrent and commonly occurs when a person rises. It is also more common in people with diabetes and Parkinson's disease.
  • Vasovagal episodes tend to have a precipitating factor (like sleep deprivation or extreme emotions) and occur for longer than five seconds.

Lab Tests

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

Other Tests and Procedures

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

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

Treatment

The treatment of lightheadedness depends on the underlying cause. Because the range of disorders that can cause lightheadedness is so broad, the list of potential treatments is vast.

For most people who experience lightheadedness, in whom 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.

A Word From Verywell

Lightheadedness—a feeling of faintness—is usually a transient symptom whose cause is benign and easily treated. However, presyncope can sometimes be a warning sign of a more serious or even potentially life-threatening condition. This is why lightheadedness should never be ignored, particularly if it is severe, recurrent, or chronic.

To help pinpoint the cause, keep a record of the timing and circumstances of the event and provide your doctor with a complete rundown of your medical history, including any medical conditions you have (or had in the past) and any medications you take.

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