SYNCOPE

64 SYNCOPE

General Discussion

Syncope is a sudden, unexpected loss of consciousness associated with a loss of postural tone with spontaneous recovery. A syncopal event is one of the more dramatic and anxiety-provoking symptoms encountered by patients, and often produces a diagnostic dilemma for the clinician. However, syncope is a common manifestation of numerous disorders with a final common pathway of insufficient cerebral blood flow to maintain consciousness. Syncope must be differentiated from other disorders of altered consciousness, including seizures, sleep disorders, metabolic disorders, vertigo, presyncope, and psychiatric disorders.

In the evaluation of syncope, proving a specific diagnosis is often difficult due to a lack of residual abnormalities on examination or on initial diagnostic studies. The clinician must remember that syncope is a symptom, and not a disease. By possessing an understanding of the common etiologies which cause syncope, the clinician can focus the history, physical examination, and diagnostic evaluation in each specific case. An understanding of the available diagnostic tests and their indications is imperative.

The differential diagnosis of syncope is broad, and prevalence varies depending upon research methods employed in each study. The most common causes of syncope are vasovagal syncope, arrhythmias, and orthostatic hypotension. One should remember that as many as half of patients have syncope of unknown cause after a standard diagnostic evaluation.

Many algorithms exist for the evaluation of syncope, and most emphasize the importance of the history and physical examination in making an accurate diagnosis. A position paper published by the American College of Physicians presents the following important features in guiding diagnosis:

• Separate patients into diagnostic, suggestive, and unexplained categories on the basis of the history, physical examination, and ECG findings.

• Separate patients with unexplained syncope further on the basis of age and the presence of organic heart disease or an abnormal ECG.

• Use echocardiography and treadmill stress testing to evaluate and quantify the degree of heart disease

• Reserve Holter monitoring and electrophysiology studies for patients with confirmed heart disease.

• Employ tilt testing, loop recorders, and psychiatric evaluation in patients with recurrent unexplained syncope and no suspected heart disease or a negative cardiac evaluation.

Although algorithms may provide a guide for the evaluation of syncope, the various available algorithms each contain controversial elements. In addition, algorithms do not consider every clinical situation and are not designed to replace individual clinician judgment. The physician should understand the approach to the patient with syncope first, and then consult algorithms to focus the diagnostic evaluation.

Medications Associated with Syncope

Anticholinergic agents

Antiparkinsonian agents

Beta-adrenergic blockers

Causes of Syncope

Reflex mediated

• Situational (cough, defecation, micturition, swallow)

• Carotid sinus hypersensitivity

• Hypertrophic cardiomyopathy

• Valvular disease

Medication effects

Metabolic disorders

• Adrenal failure

Neurologic causes

• Migraine headache

• Transient ischemic attack

Psychiatric causes

• Major depression

• Panic disorder

• Pseudoseizures

Tags: Instant Work-ups A Clinical Guide to Medicine

Aug 17, 2016 | Posted by admin in PEDIATRICS | Comments Off

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