Syncope, commonly known as fainting or passing out, involves a temporary loss of consciousness. This brief episode typically results in an individual becoming unconscious and going limp, followed by a swift recovery. While syncope can appear similar to a seizure, they are distinct physiological events with significantly different underlying causes and mechanisms. Understanding these distinctions is important for recognizing what is happening and knowing how to respond.
The Mechanics of Syncope
Syncope occurs when there is a sudden and temporary reduction in blood flow to the brain. This transient lack of oxygen and nutrients causes the brain to temporarily malfunction, leading to loss of consciousness and muscle tone. The circulatory system plays a central role in maintaining adequate blood supply. When the heart’s pumping action or blood vessels’ ability to regulate blood pressure is impaired, blood can pool in other parts of the body, particularly the legs, reducing the volume reaching the head.
The body has mechanisms to counteract gravity and ensure consistent blood flow to the brain, even when standing. However, in a syncopal episode, these regulatory systems falter, causing blood pressure to drop below what is needed to perfuse the brain. Once an individual falls or lies down, gravity no longer works against blood flow to the head, and blood supply quickly restores, leading to a rapid regain of consciousness. This spontaneous recovery without lasting effects is a hallmark of syncope.
Common Triggers for Syncope
Syncope can be provoked by various factors, ranging from harmless situations to more serious underlying health issues. One of the most common types is reflex syncope, often called neurally mediated syncope or vasovagal syncope. This occurs when the nervous system overreacts to certain triggers, causing a sudden drop in heart rate and widening of blood vessels, which leads to reduced blood flow to the brain. Common triggers for vasovagal syncope include emotional distress, pain, the sight of blood or needles, prolonged standing, or being in a hot environment.
Another type is orthostatic hypotension, where fainting happens due to a sudden drop in blood pressure upon standing up quickly. Gravity pulls blood into the legs, and if the body’s compensatory mechanisms, like increasing heart rate or constricting blood vessels, do not respond adequately, blood flow to the brain decreases. This is common in elderly individuals and can be worsened by dehydration or certain medications. Situational syncope is a specific form of reflex syncope triggered by activities such as coughing, sneezing, swallowing, urinating, defecating, or even heavy exertion.
Cardiac syncope, while less common, can be a sign of a more serious condition. It results from an issue with the heart or blood vessels that impedes sufficient blood flow to the brain. Causes include abnormal heart rhythms (arrhythmias), heart valve diseases, or other structural heart problems. Unlike other types, cardiac syncope often occurs suddenly, sometimes without warning signs.
Syncope Versus Seizures
Distinguishing between syncope and a seizure is important due to their different causes and implications. Syncope has a more gradual onset, often preceded by warning signs such as lightheadedness, nausea, sweating, blurred vision, or a feeling of warmth. Seizures, on the other hand, can have a more sudden onset, although some forms may also have pre-seizure sensations.
Movements during a syncopal episode are brief and irregular, sometimes involving a few jerks or stiffening of the body. These movements are not sustained or rhythmic like the generalized convulsions seen in many types of seizures. Seizures involve abnormal electrical activity in the brain, leading to uncontrolled movements, which can be more prolonged and patterned.
The duration of unconsciousness also differs; syncope results in a very brief loss of consciousness, lasting from a few seconds to less than a minute, with rapid recovery. Seizures involve a longer period of unconsciousness, potentially lasting several minutes. Following a syncopal event, individuals regain full alertness quickly and do not experience significant confusion or fatigue. In contrast, after a seizure, a person enters a post-ictal state characterized by confusion, drowsiness, headache, or muscle soreness, which can last for minutes to hours. Incontinence is less common in syncope but occurs more frequently during seizures.
Responding to Syncope and Next Steps
If someone faints, ensure their safety and promote blood flow to the brain. Help the person lie down flat on their back, and if possible, elevate their legs about 12 inches above heart level. Loosen any tight clothing around their neck or waist to aid circulation. Most individuals will regain consciousness within 20 seconds to one minute once blood flow to the brain is restored.
Once conscious, reassure them and help them sit up slowly after a few minutes. If the person does not regain consciousness promptly, or if they are not breathing, immediate medical attention is necessary, and CPR should be initiated if indicated. Seek medical advice after any fainting spell, especially if:
It is a first-time occurrence.
An injury resulted from the fall.
The syncope happens during exercise.
It occurs with chest pain.
It occurs with shortness of breath.
Recurrent episodes also warrant a medical evaluation to determine the underlying cause and guide appropriate management.