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. [1][3][4][5][6][7][8][9][10]
Recurrent syncope Hypotension that result from carotid sinus stimulation leads to a transient brain hypoperfusion leading to loss of consciousness.[1][2][4][5][7][8][9][10]
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.[2][5][7][10]
Recurrent dizziness This is also a result of brain hypopperfusion as described above.[1][4][7][10]
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.[1][2][3][7][8][9][10]
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. [1][5][7][9]
References
  1. HUNTER C. RECURRING SYNCOPE IN PATIENTS OVER 45 YEARS OF AGE Can Med Assoc J [online] 1948 Sep, 59(3):217-220 [viewed 04 November 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1591191
  2. LEATHAM A. Carotid sinus syncope. Br Heart J [online] 1982 May, 47(5):409-410 [viewed 04 November 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC481156
  3. TROUT HH III, BROWN LL, THOMPSON JE. Carotid Sinus Syndrome: Treatment by Carotid Sinus Denervation Ann Surg [online] 1979 May, 189(5):575-580 [viewed 04 November 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1397187
  4. DAVIES AB, STEPHENS MR, DAVIES AG. Carotid sinus hypersensitivity in patients presenting with syncope. Br Heart J [online] 1979 Nov, 42(5):583-586 [viewed 04 November 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC482204
  5. SIMON RP. Syncope and transient loss of consciousness. Differential diagnosis and treatment. West J Med [online] 1975 Aug, 123(2):164-170 [viewed 04 November 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1129855
  6. BRIGNOLE M., MENOZZI C.. The natural history of carotid sinus syncope and the effect of cardiac pacing. Europace [online] December, 13(4):462-464 [viewed 04 November 2014] Available from: doi:10.1093/europace/euq516
  7. PALLAIS J. CARL, SCHLOZMAN STEVEN C., PUIG ALBERTO, PURCELL JOHN J., STERN THEODORE A.. Fainting, Swooning, and Syncope. Prim. Care Companion CNS Disord. [online] 2011 July [viewed 04 November 2014] Available from: doi:10.4088/PCC.11f01187
  8. LOPES R,GONÇALVES A,CAMPOS J, FRUTUOSO J, SILVA A,TOUGUINHA C,FREITAS J, JÚLIAMACIEL M. The role of pacemaker in hypersensitive carotid sinus syndrome. Oxford journals. First published online: 18 December 2010.[viewed on 4 Nov 2014] Available from; DOI: http://dx.doi.org/10.1093/europace/euq455 572-575
  9. Moya A, Sutton R, Ammirati F, Blanc JJ, Brignole M, Dahm JB, et al. Guidelines for the diagnosis and management of syncope (version 2009): the Task Force for the Diagnosis and Management of Syncope of the European Society of Cardiology (ESC). Eur Heart J[online] 2009;30:2631-71. [viewed on 4 Nov 2014] Available from;doi:10.1093/eurheartj/ehp298.
  10. Grilley JG, Herd B, Khurana CS, Appleby CA, de Belder MA, Davies A, et al. Permanent cardiac pacing in elderly patients with recurrent falls, dizziness and syncope, and a hypersensitive cardioinhibitory reflex. Postgrad Med J[online] 1997;73:415-8. [viewed on 4 Nov 2014] Available from; doi:10.1136/pgmj.73.861.415.

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.[1][2][3][5]
Bradycardia Results from increased vagal tone on the cardiac pacemaker. Is marked in cardioinhibitory type CSS.[1] [2][3]
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.[1][2][3]
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.[1][2][4][5][6]
References
  1. DAVIES AB, STEPHENS MR, DAVIES AG. Carotid sinus hypersensitivity in patients presenting with syncope. Br Heart J [online] 1979 Nov, 42(5):583-586 [viewed 04 November 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC482204
  2. Moya A, Sutton R, Ammirati F, Blanc JJ, Brignole M, Dahm JB, et al. Guidelines for the diagnosis and management of syncope (version 2009): the Task Force for the Diagnosis and Management of Syncope of the European Society of Cardiology (ESC). Eur Heart J[online] 2009;30:2631-71. [viewed on 4 Nov 2014] Available from;doi:10.1093/eurheartj/ehp298.
  3. Grilley JG, Herd B, Khurana CS, Appleby CA, de Belder MA, Davies A, et al. Permanent cardiac pacing in elderly patients with recurrent falls, dizziness and syncope, and a hypersensitive cardioinhibitory reflex. Postgrad Med J[online] 1997;73:415-8. [viewed on 4 Nov 2014] Available from; doi:10.1136/pgmj.73.861.415.
  4. TROUT HH III, BROWN LL, THOMPSON JE. Carotid Sinus Syndrome: Treatment by Carotid Sinus Denervation Ann Surg [online] 1979 May, 189(5):575-580 [viewed 05 November 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1397187
  5. WALSH T, CLINCH D, COSTELLOE A, MOORE A, SHEEHY T, WATTS M, BRYANT CA, CLOSE J, GONZALEZ J, OULDRED E, PATHANSALI R, SWIFT CG, LYONS D, JACKSON SH. Carotid sinus massage--how safe is it? Age Ageing [online] 2006 Sep, 35(5):518-20 [viewed 12 November 2014] Available from: doi:10.1093/ageing/afl057
  6. Kurtz KJ. Bruits and Hums of the Head and Neck. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 18. Available from: http://www.ncbi.nlm.nih.gov/books/NBK289/

Differential Diagnoses

Fact Explanation
Vasovagal syncope Results from reduced cardiac output and systemic vascular resistance. Vasovagal syncope is triggered by emotionally challenging situations for e.g. seeing blood,hearing bad news etc. It may arise in response to carotid sinus hypersensitivity also. What ever the trigger may be, it leads to an exaggerated vagal response resulting in reduced heart rate and blood pressure (due to reduced systemic vascular resistance) thus reducing cerebral blood flow which cause temporary loss of consciousness.[1][2]
Orthostatic hypotension This results from a postural reduction in cerebral perfusion which in turn is due to a drop in vascular tone. When a person stands up there is a sudden drop in his mean arterial pressure, either due to blood pooling in legs or reduced systemic vascular resistance. The sudden drop in blood pressure cause a sudden reduction in cerebral perfusion leading to syncope followed by quick recovery as the person collapses and the increased venous return restores blood pressure and cerebral perfusion.[1][2]
Cardiogenic syncope Results from a decrease in cardiac output which can be brought about by bradyarrhythmias and tachyarrhythmias (eg, heart block, sick sinus syndrome, supraventricular tachycardias etc.) and structural problems (eg, aortic stenosis, mitral stenosis, cardiomyopathies, atrial myxomas etc.). Reduction in cardiac out put lead to reduced cerebral perfusion and syncope. [1][2]
Panic disorder In this case syncope will be associated with other symptoms of a panic attack, such as feelings of dread or intense fear, sweating, palpitations, tremor, reduced field of vision, etc.[1][2]
Autonomic dysregulation This may result in impaired vascular tone and reduced blood pressure resulting in syncope. Diseases such as Parkinson's disease, diabetes, alcohol abuse, toxin ingestion can lead to autonomic dysregulation. [1][2]
References
  1. PALLAIS J. CARL, SCHLOZMAN STEVEN C., PUIG ALBERTO, PURCELL JOHN J., STERN THEODORE A.. Fainting, Swooning, and Syncope. Prim. Care Companion CNS Disord. [online] 2011 July [viewed 04 November 2014] Available from: doi:10.4088/PCC.11f01187
  2. Moya A, Sutton R, Ammirati F, Blanc JJ, Brignole M, Dahm JB, et al. Guidelines for the diagnosis and management of syncope (version 2009): the Task Force for the Diagnosis and Management of Syncope of the European Society of Cardiology (ESC). Eur Heart J[online] 2009;30:2631-71. [viewed on 4 Nov 2014] Available from;doi:10.1093/eurheartj/ehp298.

Investigations - for Diagnosis

Fact Explanation
Electrocardiogram Done to help in the diagnosis of arrhythmogenic syncope.[2][3]
Echocardiogram Is done to screen for structural and valvular heart disease and functional disease of the myocardium. [2][3]
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.[2][3]
Carotid sinus massage This is capable of reproducing symptoms of CSS. Should be done especially on all patients above 40 years of age.[2][3]
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. [1][3]
Computed tomography (CT) neck Should be done when there is suspicion of a tumor mass compressing the carotid sinus bringing about CSS.[1]
References
  1. DA GAMA AMéRICO DINIS, CABRAL GONçALO M.. Carotid body tumor presenting with carotid sinus syndrome. Journal of Vascular Surgery [online] 2010 December, 52(6):1668-1670 [viewed 04 November 2014] Available from: doi:10.1016/j.jvs.2010.07.016
  2. PALLAIS J. CARL, SCHLOZMAN STEVEN C., PUIG ALBERTO, PURCELL JOHN J., STERN THEODORE A.. Fainting, Swooning, and Syncope. Prim. Care Companion CNS Disord. [online] 2011 July [viewed 04 November 2014] Available from: doi:10.4088/PCC.11f01187
  3. Moya A, Sutton R, Ammirati F, Blanc JJ, Brignole M, Dahm JB, et al. Guidelines for the diagnosis and management of syncope (version 2009): the Task Force for the Diagnosis and Management of Syncope of the European Society of Cardiology (ESC). Eur Heart J[online] 2009;30:2631-71. [viewed on 4 Nov 2014] Available from;doi:10.1093/eurheartj/ehp298.

Investigations - Fitness for Management

Fact Explanation
Complete blood count Done to detect presence anemia and assess other blood parameters prior to planing surgery[1]
Serum electrolytes and serum creatinine Done to assess the baseline renal function prior to planing surgery[1]
Electrocardiogram Done to assess the cardiac function prior to anesthesia. Done in older patients and those with a history of ischemic heart disease only.[1]
2D Echocardiogram Done to assess the cardiac function and structure prior to planing surgery in patient with heart disease.[1]
Fasting/random blood glucose level Done prior to planing surgery as blood sugar levels affect outcome of surgery.[1]
Lung function tests Can be done to assess the cardio-respiratory reserve prior to anesthesia. Also done in patients with cardio-respiratory problems.[1]
References
  1. ADITYA K, UMA S.Role of routine laboratory investigations in preoperative evaluation. J Anaesthesiol Clin Pharmacol. [online] 2011 Apr-Jun. [viewed on 12 Nov 2014] vol27(2): 174–179. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3127294/

Management - General Measures

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.[1]
Life style changes Life style modifications in relation to avoid wearing tight collars round neck and other carotid sinus stimulatory events shouldbe employed.[1]
References
  1. Moya A, Sutton R, Ammirati F, Blanc JJ, Brignole M, Dahm JB, et al. Guidelines for the diagnosis and management of syncope (version 2009): the Task Force for the Diagnosis and Management of Syncope of the European Society of Cardiology (ESC). Eur Heart J[online] 2009;30:2631-71. [viewed on 4 Nov 2014] Available from;doi:10.1093/eurheartj/ehp298.

Management - Specific Treatments

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.[1][2]
Surgery Unilateral or bilateral carotid sinus denervation has shown to either completely abolish or markedly improve symptoms of CSS.[3]
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.[4]
Fludrocortisone Several studies have shown that treatment with fludrocortisone is effective to reduce symptoms of vasodepressor CSS.[5]
References
  1. BRIGNOLE M., MENOZZI C.. The natural history of carotid sinus syncope and the effect of cardiac pacing. Europace [online] December, 13(4):462-464 [viewed 04 November 2014] Available from: doi:10.1093/europace/euq516
  2. LOPES R,GONÇALVES A,CAMPOS J, FRUTUOSO J, SILVA A,TOUGUINHA C,FREITAS J, JÚLIAMACIEL M. The role of pacemaker in hypersensitive carotid sinus syndrome. Oxford journals. First published online: 18 December 2010. Available from; DOI: http://dx.doi.org/10.1093/europace/euq455 572-575
  3. TROUT HH III, BROWN LL, THOMPSON JE. Carotid Sinus Syndrome: Treatment by Carotid Sinus Denervation Ann Surg [online] 1979 May, 189(5):575-580 [viewed 05 November 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1397187
  4. ROMME JJ, REITSMA JB, BLACK CN, COLMAN N, SCHOLTEN RJ, WIELING W, VAN DIJK N. Drugs and pacemakers for vasovagal, carotid sinus and situational syncope. Cochrane Database Syst Rev [online] 2011 Oct 5:CD004194 [viewed 05 November 2014] Available from: doi:10.1002/14651858.CD004194.pub3
  5. DA COSTA D, MCINTOSH S, KENNY RA. Benefits of fludrocortisone in the treatment of symptomatic vasodepressor carotid sinus syndrome. Br Heart J [online] 1993 Apr, 69(4):308-310 [viewed 05 November 2014] Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1025042