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Situational syncope is often triggered by urination, swallowing, or coughing. [2] Carotid sinus syncope is due to pressure on the carotid sinus in the neck. [2] The underlying mechanism involves the nervous system slowing the heart rate and dilating blood vessels, resulting in low blood pressure and thus not enough blood flow to the brain. [2]
The carotid sinus baroreceptor can be oversensitive to manual stimulation from the pressure applied at the carotid sinus at the carotid bifurcation. It is a condition known as 'carotid sinus hypersensitivity' (CSH), 'carotid sinus syndrome' or 'carotid sinus syncope', in which manual stimulation causes large changes in heart rate and blood ...
Neurally mediated syncope may also occur when an area in the neck known as the carotid sinus is pressed. [1] A normal response to carotid sinus massage is reduction in blood pressure and slowing of the heart rate. Especially in people with hypersensitive carotid sinus syndrome this response can cause syncope or presyncope. [9]
Baroreceptors can also become oversensitive in some people (usually the carotid baroreceptors in older males). This can lead to bradycardia, dizziness and fainting (syncope) from touching the neck (often whilst shaving). This is an important cause to exclude in men having pre-syncope or syncope symptoms.
[8] [9] Electrical stimulation of the external surfaces of the carotid sinus activates baroreceptors believed to be in the adventitia of the artery. This stimulates an afferent limb which activates central nervous system pathways that in turn exert two different but synergistic autonomic effects on the body.
An increase in blood pressure can be caused by increased cardiac output, increased total peripheral resistance, or both. The baroreceptors in the carotid sinus sense this increase in blood pressure and relay the information to the cardiovascular centres in the medulla oblongata.
With 15.5 million U.S. adults currently diagnosed with ADHD, there is a growing focus on warning signs of the disorder. Mental health experts share the most common signs and symptoms.
The term is often associated with a sudden traumatic loss of consciousness caused by a physical blow. Single powerful blows to the head (particularly the jawline and temple) can produce a cerebral concussion or a carotid sinus reflex with syncope and cause a sudden, dramatic KO.