Syncope Flashcards
A vasovagal episode (or attack) is caused by?
a problem with the autonomic nervous system regulating blood flow to the brain.
When the vagus nerve receives a strong stimulus, such as an emotional event, painful sensation or change in temperature it can stimulate the parasympathetic nervous system.
Parasympathetic activation counteracts the sympathetic nervous system, which keeps the smooth muscles in blood vessels constricted.
As the blood vessels delivering blood to the brain relax, the blood pressure in the cerebral circulation drops, leading to hypoperfusion of brain tissue. This causes the patient to lose consciousness and “faint”.
Patients often remember the event and can recall how they felt prior to fainting. This is called the prodrome, and involves feeling:
Hot or clammy
Sweaty
Heavy
Dizzy or lightheaded
Vision going blurry or dark
Headache
A collateral history from someone that witnessed the event is essential to get an accurate impression of what happened. During a vasovagal episode they may describe the person:
Suddenly losing consciousness and falling to the ground
Unconscious on the ground for a few seconds to a minute as blood returns to their brain
There may be some twitching, shaking or convulsion activity, which can be confused with a seizure
Postictal patients have a ?
prolonged period of confusion, drowsiness, irritability and disorientation.
postictal period that follows a seizure
There may be incontinence with both ?
seizures and syncopal episodes
Primary syncope (simple fainting):
Dehydration
Missed meals
Extended standing in a warm environment, such as a school assembly
A vasovagal response to a stimuli, such as sudden surprise, pain or the sight of blood
Secondary causes of syncope?
Hypoglycaemia
Dehydration
Anaemia
Infection
Anaphylaxis
Arrhythmias
Valvular heart disease
Hypertrophic obstructive cardiomyopathy
History of syncope, Take a thorough history focusing on eliciting several key points, ideally with the help of a witness:
Features that distinguish a syncopal episode from a seizure
After exercise? Syncope after exercise is more likely to be secondary to an underlying condition.
Triggers?
Concurrent illness? Do they have a fever or signs of infection?
Injury secondary to the faint? Do they have a head injury?
Associated cardiac symptoms, such as palpitations or chest pain?
Associated neurological symptoms?
Seizure activity?
Family history, particularly cardiac problems or sudden death?
Differences between syncope and seizure?
Syncope: Prolonged upright position before the event, lightheaded before the event, sweating before the event, blurring of clouding of vision before the event, reduced tune during the episode, return of consciousness shortly after falling, no prolonged post-ictal period
Seizure: epilepsy aura (smells, tastes or deja vu) before the event, head turning or abnormal limb positions, tonic clonic activity, tongue biting, cyanosis, lasts more than 5 minutes, prolonged post-ictal period
Perform a thorough examination focusing on eliciting several key points:
Are there any physical injuries as a result of the faint, for example a head injury?
Is there a concurrent illness, for example an infection or gastroenteritis?
Neurological examination
Cardiac examination, specifically assessing pulses, heart rate, rhythm and murmurs
Lying and standing blood pressure
Investigations for syncope?
ECG, particularly assessing for arrhythmia and the QT interval for long QT syndrome
24 hour ECG if paroxysmal arrhythmias are suspected
Echocardiogram if structural heart disease is suspected
Bloods, including a full blood count (anaemia), electrolytes (arrhythmias and seizures) and blood glucose (diabetes)
Once a simple vasovagal episode is diagnosed, reassurance and simple advice can be given to:
Avoid dehydration
Avoid missing meals
Avoid standing still for long periods
When experiencing prodromal symptoms such as sweating and dizziness, sit or lie down, have some water or something to eat and wait until feeling better
