Carotid sinus syncope - Clinicals, Diagnosis, and Management

Neurology

Clinicals - History

Fact Explanation
Introduction This is a condition brought on due to exaggerated responsiveness to stimulation of barorecptors in the carotid sinus. This condition is more common among older males. Carotid baroreceptors play an important role in the blood pressure homeostasis. They recognize changes in transmural pressure and stretch. These then generate a neuronal impulses which are transmitted to and then processed by nuclei in brain stem. The heart rate and vasomotor tone are changed in response to these stimuli making changes in the blood pressure as needed. Carotid sinus hyperresponsiveness to these stimuli leads to an exaggerated response resulting in bradycardia, hypotension, syncope etc. This hyperresposiveness can be the manifestation of a generalized autonomic dysregulation or a defect in any part of the reflex arc. Diagnosis of carotid sinus syndrome(CSS) is made when there is an asystole of >3 s and/or a fall in systolic blood pressure of >50 mmHg during carotid sinus massage together with reproduction of spontaneous symptoms. CSS has a cardioinhibitory component which results from increased vagal tone and a vasodepressor component resulting from sympathetic activity withdrawal. Introduction
This is a condition brought on due to exaggerated responsiveness to stimulation of barorecptors in the carotid sinus. This condition is more common among older males. Carotid baroreceptors play an important role in the blood pressure homeostasis. They recognize changes in transmural pressure and stretch. These then generate a neuronal impulses which are transmitted to and then processed by nuclei in brain stem. The heart rate and vasomotor tone are changed in response to these stimuli making changes in the blood pressure as needed. Carotid sinus hyperresponsiveness to these stimuli leads to an exaggerated response resulting in bradycardia, hypotension, syncope etc. This hyperresposiveness can be the manifestation of a generalized autonomic dysregulation or a defect in any part of the reflex arc. Diagnosis of carotid sinus syndrome(CSS) is made when there is an asystole of >3 s and/or a fall in systolic blood pressure of >50 mmHg during carotid sinus massage together with reproduction of spontaneous symptoms. CSS has a cardioinhibitory component which results from increased vagal tone and a vasodepressor component resulting from sympathetic activity withdrawal.
Recurrent syncope Hypotension that result from carotid sinus stimulation leads to a transient brain hypoperfusion leading to loss of consciousness. Recurrent syncope
Hypotension that result from carotid sinus stimulation leads to a transient brain hypoperfusion leading to loss of consciousness.
Non accidental falls These patients experience recurrent episodes of non accidental and unexplained falls which occur when there is transinet brain hypoperfusion and loss of consciousness. Non accidental falls
These patients experience recurrent episodes of non accidental and unexplained falls which occur when there is transinet brain hypoperfusion and loss of consciousness.
Recurrent dizziness This is also a result of brain hypopperfusion as described above. Recurrent dizziness
This is also a result of brain hypopperfusion as described above.
Symptoms precipitated by a stimulating event events such as wearing garments with tight collar around neck, turning head, feeling for carotid pulse etc can stimulate the hypersensitive carotid baroreceptors and bring about symptoms. Symptoms precipitated by a stimulating event
events such as wearing garments with tight collar around neck, turning head, feeling for carotid pulse etc can stimulate the hypersensitive carotid baroreceptors and bring about symptoms.
Onset of symptoms followed surgery, trauma, radiation, tumor etc in the neck region These may cause mechanical dysruption to the carotid sinus region and cause carotid baroraceptor hypersentivity. Onset of symptoms followed surgery, trauma, radiation, tumor etc in the neck region
These may cause mechanical dysruption to the carotid sinus region and cause carotid baroraceptor hypersentivity.

Clinicals - Examination

Fact Explanation
Symptoms brought on by carotid massage CSS is condition that results due to hypersensitivity of the carotid baroreceptors to mildest stimulation. Carotid massage or slight pressure at the carotid sinus will reproduce the symptoms and signs of CSS. Before performing carotid sinus massage it is important to exclude presence of a bruit in order to prevent dislodging a plaque or thrombus in the carotid bifucation that can cause stroke. Symptoms brought on by carotid massage
CSS is condition that results due to hypersensitivity of the carotid baroreceptors to mildest stimulation. Carotid massage or slight pressure at the carotid sinus will reproduce the symptoms and signs of CSS. Before performing carotid sinus massage it is important to exclude presence of a bruit in order to prevent dislodging a plaque or thrombus in the carotid bifucation that can cause stroke.
Bradycardia Results from increased vagal tone on the cardiac pacemaker. Is marked in cardioinhibitory type CSS. Bradycardia
Results from increased vagal tone on the cardiac pacemaker. Is marked in cardioinhibitory type CSS.
Hypotension This results mainly due to reduced peripheral resistance due to an imbalance between the parasympathetic and sympathetic effect on peripheral vessels. In vasodepressor type of CSS there is significant hypotension without much reduction in heart rate. Hypotension
This results mainly due to reduced peripheral resistance due to an imbalance between the parasympathetic and sympathetic effect on peripheral vessels. In vasodepressor type of CSS there is significant hypotension without much reduction in heart rate.
Bruit auscultated over carotid artery May be associated with some cases of CSS. These patients may have carotid narrowing due to atherosclerosis with risk of ischemic stroke. Cervical bruit may also be present in conditions such as thyrotoxicosis, radiated murmur of aortic stenosis or mitral valve prolapse, bruit of high cardiac output and the venous hum in some healthy childern. Bruit auscultated over carotid artery
May be associated with some cases of CSS. These patients may have carotid narrowing due to atherosclerosis with risk of ischemic stroke. Cervical bruit may also be present in conditions such as thyrotoxicosis, radiated murmur of aortic stenosis or mitral valve prolapse, bruit of high cardiac output and the venous hum in some healthy childern.

Investigations - Diagnosis

Fact Explanation
Electrocardiogram Done to help in the diagnosis of arrhythmogenic syncope. Electrocardiogram
Done to help in the diagnosis of arrhythmogenic syncope.
Echocardiogram Is done to screen for structural and valvular heart disease and functional disease of the myocardium. Echocardiogram
Is done to screen for structural and valvular heart disease and functional disease of the myocardium.
Orthostatic challenge test Done to assist diagnosis of orthostatic hypotension. Threre are two methods that can carried out; ‘active standing’, (patients arise actively from supine to erect), and the head up tilt. Orthostatic challenge test
Done to assist diagnosis of orthostatic hypotension. Threre are two methods that can carried out; ‘active standing’, (patients arise actively from supine to erect), and the head up tilt.
Carotid sinus massage This is capable of reproducing symptoms of CSS. Should be done especially on all patients above 40 years of age. Carotid sinus massage
This is capable of reproducing symptoms of CSS. Should be done especially on all patients above 40 years of age.
24 hour Holter monitoring Can be used to screening for intermitent dysrhythmias that can result in arrhythmogenic syncope, but are not detected by routine ECG. 24 hour Holter monitoring
Can be used to screening for intermitent dysrhythmias that can result in arrhythmogenic syncope, but are not detected by routine ECG.
Computed tomography (CT) neck Should be done when there is suspicion of a tumor mass compressing the carotid sinus bringing about CSS. Computed tomography (CT) neck
Should be done when there is suspicion of a tumor mass compressing the carotid sinus bringing about CSS.

Investigations - Management

Fact Explanation
Complete blood count Done to detect presence anemia and assess other blood parameters prior to planing surgery Complete blood count
Done to detect presence anemia and assess other blood parameters prior to planing surgery
Serum electrolytes and serum creatinine Done to assess the baseline renal function prior to planing surgery Serum electrolytes and serum creatinine
Done to assess the baseline renal function prior to planing surgery
Electrocardiogram Done to assess the cardiac function prior to anesthesia. Done in older patients and those with a history of ischemic heart disease only. Electrocardiogram
Done to assess the cardiac function prior to anesthesia. Done in older patients and those with a history of ischemic heart disease only.
2D Echocardiogram Done to assess the cardiac function and structure prior to planing surgery in patient with heart disease. 2D Echocardiogram
Done to assess the cardiac function and structure prior to planing surgery in patient with heart disease.
Fasting/random blood glucose level Done prior to planing surgery as blood sugar levels affect outcome of surgery. Fasting/random blood glucose level
Done prior to planing surgery as blood sugar levels affect outcome of surgery.
Lung function tests Can be done to assess the cardio-respiratory reserve prior to anesthesia. Also done in patients with cardio-respiratory problems. Lung function tests
Can be done to assess the cardio-respiratory reserve prior to anesthesia. Also done in patients with cardio-respiratory problems.

Management - Supportive

Fact Explanation
Education of patient and family Patient and the family should be educated regarding the nature of the condition, available treatment options, precipitating factors and importance of avoiding them. Education of patient and family
Patient and the family should be educated regarding the nature of the condition, available treatment options, precipitating factors and importance of avoiding them.
Life style changes Life style modifications in relation to avoid wearing tight collars round neck and other carotid sinus stimulatory events shouldbe employed. Life style changes
Life style modifications in relation to avoid wearing tight collars round neck and other carotid sinus stimulatory events shouldbe employed.

Management - Specific

Fact Explanation
Permanent pacemaker implantaion This mode of treatment is most effective in patients with cardioinhibitory type of CSS. Dual-chamber pacing is considered the best type of pacing. Cardiac pacing is effective to alleviate syncope but less effective in preventing pre-syncope. It counteracts the asystole associated with CSS which brings about syncope. Permanent pacemaker implantaion
This mode of treatment is most effective in patients with cardioinhibitory type of CSS. Dual-chamber pacing is considered the best type of pacing. Cardiac pacing is effective to alleviate syncope but less effective in preventing pre-syncope. It counteracts the asystole associated with CSS which brings about syncope.
Surgery Unilateral or bilateral carotid sinus denervation has shown to either completely abolish or markedly improve symptoms of CSS. Surgery
Unilateral or bilateral carotid sinus denervation has shown to either completely abolish or markedly improve symptoms of CSS.
Midodrine Some studies have shown that midodrine which is an alpha-1 agonist can reduce the occurrence of syncope due to CSS when compared to a placebo. Midodrine
Some studies have shown that midodrine which is an alpha-1 agonist can reduce the occurrence of syncope due to CSS when compared to a placebo.
Fludrocortisone Several studies have shown that treatment with fludrocortisone is effective to reduce symptoms of vasodepressor CSS. Fludrocortisone
Several studies have shown that treatment with fludrocortisone is effective to reduce symptoms of vasodepressor CSS.

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