Neurology
Summary
Syncope is a condition that's often confused with seizures, and its important to understand the differences between them. Syncope is a transient loss of consciousness due to global cerebral hypoperfusion with relative rapid resolution, while seizures are a paroxysmal temporary clinical change (in behavior, LOC or movement) due to abnormally excessive or synchronous neuronal activity in the brain.
The most common causes of syncope can be divided into reflex, cardiac, orthostatic, and cerebrovascular varieties. Vasovagal syncope is a type of reflex syncope (in which stimulation of the vagus nerve leads to sudden drop in blood pressure and heart rate); reflex syncope also includes situational syncope and carotid sinus syndrome. Cardiac syncope can occur as a result of arrhythmia, cardiomyopathy, structural heart disease, acute MI or PE. Orthostatic syncope results from low blood pressure secondary to volume loss or dysautonomia. Cerebrovascular syncope results from global hypoperfusion secondary to vascular pathology like bilateral carotid artery occlusion or dissection, vertebrobasilar insufficiency, or subclavian steal syndrome.
Clinically, syncope typically lasts less than 20 seconds, involves a loss of tone, and rarely has more than 10 jerks. It never occurs during sleep and features a rapid return to baseline following the event. The prodrome for syncope may involve pallor, diaphoresis, abdominal pain, and nausea. In contrast, seizures can occur during sleep, last for several minutes, and have a delayed return to baseline (known as the post-ictal state), with the possibility of lingering neurologic deficits.
Lesson Outline
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FAQs
The essential way to differentiate between syncope and a seizure is the cause. Syncope is a transient loss of consciousness due to a sudden drop in the amount of blood the brain receives. On the other hand, a seizure is an uncontrolled electrical disturbance in the brain, causing temporary clinical change in behavior, level of consciousness, or movement.
There are several different symptoms exhibited during the prodrome phases of syncope and seizure. For syncope, an individual may experience symptoms like nausea, pallor, diaphoresis, and abdominal pain. Meanwhile, a seizure prodrome may include auras, focal deficits, and automatisms.
Vasovagal syncope is the most common type of syncope, caused by a sudden drop in heart rate and blood pressure due to vagus nerve stimulation. This results in a brief loss of consciousness, typically shorter than a seizure. A seizure, on the other hand, results from abnormal neuronal activity and typically lasts longer, resulting in more than 20 jerks, as opposed to fewer than 10 in syncope.
Syncope does not usually occur during sleep, as the body naturally maintains blood pressure levels. Conversely, seizures can occur during sleep, as they result from abnormal electrical activity in the brain, which can occur independently of the body's circadian rhythm.
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