What Causes Convulsive Syncope?

There are many causes of convulsive syncope, including reflex syncope (neurally mediated syncope, vasovagal syncope, vasodepressor syncope), situational syncope (or a sudden reflex response to a trigger), carotid sinus syncope, orthostatic hypotension, serious cardiovascular conditions (cardiac syncope), and Postural Orthostatic Tachycardia Syndrome (POTS).

Syncope refers to fainting or passing out that occurs when there is not enough blood flow to the brain. Convulsive syncope specifically refers to syncope accompanied by tense or rigid muscles (tonic activity) or jerking movements and muscle twitching (myoclonic activity). 

Convulsive syncope may be difficult to differentiate from a seizure, but it is not linked with epilepsy. Unconsciousness due to seizures is not considered syncope. 

Syncope is temporary, with a loss of consciousness that comes on quickly and can lead to falling, and recovery is prompt and complete. Seizures, on the other hand, occur when there is a sudden surge of abnormal electrical activity in the brain that usually affects how a person appears or acts for a short time.

Causes of convulsive syncope are the same as syncope that does not cause convulsions, and can include:

• Reflex syncope (also called neurally mediated syncope, vasovagal syncope, vasodepressor syncope, the common faint)
  • The heart slows or blood vessels dilate (widen) and blood pressure drops
  • The most frequent cause of fainting results from a reflex response to some trigger, such as: 
    • Seeing blood 
    • Donating blood or having blood drawn
    • Getting an injection 
    • Standing upright for a long time
    • Standing up quickly (a “head rush” is considered pre-syncope)
    • Sudden and unexpected trauma, stress or pain, such as being hit
  • Other types of reflex syncope include
    • Situational syncope, or a sudden reflex response to a trigger other than those listed above, such as: 
      • Coughing, sneezing, laughing, swallowing
      • Eating a meal
      • Sudden abdominal pain
      • Urinating 
      • Having a bowel movement
      • Pressure on the chest after exertion or exercise
      • Weight lifting
      • Playing a brass instrument 
  • Carotid sinus syncope 
    • Occurs in older people when pressure is applied to the carotid artery in the neck such as by a hard twist of the neck, wearing a tight collar, and pressing on the artery 
• Orthostatic hypotension 
  • Low blood pressure on standing
  • A drop in systolic blood pressure (the top number) of 20 mmHg or more on standing
• Serious cardiovascular conditions (cardiac syncope), which may be caused by”
  • Irregular heartbeat (arrhythmia) and abnormal heart rhythm
  • Aortic dissection, a tear in the aorta; very rare but life-threatening
  • Aortic valve stenosis, or a narrowing of the valve between the heart and the aorta
• Postural Orthostatic Tachycardia Syndrome (POTS)
  • Increased heart rate when standing: characterized by an increase in heart rate of at least 30 beats per minute on standing and orthostatic intolerance