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Reflex syncope can occur in otherwise healthy individuals, and has many possible causes, often trivial ones such as prolonged standing with the legs locked. [ citation needed ] The main danger of vasovagal syncope (or dizzy spells from vertigo) is the risk of injury by falling while unconscious.
Reflex syncope or neurally mediated syncope occurs when blood vessels expand and heart rate decreases inappropriately leading to poor blood flow to the brain. [1] This may occur from either a triggering event such as exposure to blood, pain, strong feelings, or a specific activity such as urination , vomiting , or coughing .
Reflex anoxic seizures are a particular type of anoxic seizure, most commonly seen in young children in whom an anoxic seizure or syncope is provoked or precipitated by a noxious stimulus (hence "reflex"). Various precipitants have been identified, but the most common is an unexpected bump to the head.
A frequent type of syncope, termed vasovagal syncope is originated by intense cardioinhibition, mediated by a sudden vagal reflex, that causes transitory cardiac arrest by asystole and/or transient total atrioventricular block. [1] [2] It is known as “Vaso-vagal Syncope”, “Neurocardiogenic Syncope” or “Neurally-mediated Reflex Syncope ...
However, if the Bezold–Jarisch reflex is activated due to the reduced ventricular volume this may trigger paradoxical bradycardia and arterial hypotension resulting in syncope. The importance of this mechanism is unclear since vaso-vagal syncope can be observed in cardiac transplant patients who are presumed to lack cardiac innervation. [6]
One response is a vasoconstriction (baroreceptor reflex), pressing the blood up into the body again. (Often, this mechanism is exaggerated and is why diastolic blood pressure is a bit higher when a person is standing up, compared to a person in the horizontal position.)
Dysautonomia, autonomic failure, or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels.
Breath-holding spells (BHS) are the occurrence of episodic apnea in children, possibly associated with syncope (loss of consciousness and changes in postural tone).. Breath-holding spells occur in approximately 5% of the population with equal distribution between males and females.