Following a syncopal event, a 40-year-old woman with a history of hypertension and recent diuretic treatment presents to the emergency department. She experienced lightheadedness, nausea, darkened vision, followed by loss of consciousness, with spontaneous recovery after 10 seconds and loss of bladder control upon awakening.

Blood pressure readings were 120/80 mm Hg supine, 110/70 mm Hg sitting, and 90/60 mm Hg standing. No focal neurologic deficits were found, cardiac exam was normal with sinus tachycardia (110 bpm) on ECG. Laboratory results were unremarkable.

Should there be a need for neuroimaging for syncope evaluation?

DEFINITIONS, CLASSIFICATIONS

Syncope is a sudden loss of consciousness due to reduced blood flow to the brain, accompanied by postural tone loss and rapid recovery, followed by an immediate return to orientation and normal behavior. Causes are reflex (neurally mediated), orthostatic hypotension, or cardiac.

Syncope can be classified into three categories based on its underlying cause: reflex (also known as neurally mediated) syncope, orthostatic hypotension syncope, and cardiac syncope.

Reflex syncope occurs due to an abnormal reflex response that causes a temporary disruption in blood flow to the brain. This can be triggered by various factors such as emotional stress, pain, dehydration, or prolonged standing.

Orthostatic hypotension syncope, on the other hand, is caused by a drop in blood pressure upon standing up, leading to decreased blood flow to the brain. Conditions such as dehydration, medications, or disorders of the autonomic nervous system can contribute to orthostatic hypotension.

Cardiac syncope is related to underlying heart conditions that affect the heart’s ability to pump blood effectively. This can include arrhythmias, structural heart defects, or other cardiac issues that result in inadequate blood flow to the brain.

• Additional tests that may be recommended include tilt table testing, implantable loop recorder, echocardiogram, stress testing, and cardiac MRI.
• It is important to consider underlying medical conditions such as arrhythmias, structural heart disease, neurologic disorders, and medication side effects in the evaluation.
• Certain red flags such as family history of sudden cardiac death, exertional syncope, or new-onset syncope in older adults may warrant further investigation.
• Multidisciplinary evaluation involving cardiologists, neurologists, and other specialists may be necessary in complex cases.

WHEN TO PURSUE ADDITIONAL TESTING

Based on diagnostic value, additional tests such as blood work, nerve evaluation, echocardiography, stress testing, and electrophysiologic testing can be ordered according to initial evaluation results.

ROLE OF ELECTROENCEPHALOGRAPHY

If the diagnosis is still uncertain after initial assessment, EEG during tilt-table testing can help differentiate syncope, pseudosyncope, and epilepsy. EEG patterns vary in each condition. Routine neuroimaging is of limited diagnostic value and high cost.

CASE CONTINUED

For the 40-year-old patient, dehydration due to diuretic use may be a contributing factor. Loss of bladder control is not necessarily indicative of neurologic disease and can occur in syncope. Neuroimaging is deemed unnecessary based on the patient’s presentation and examination, with orthostatic intolerance as a probable cause.

For the most recent information on syncope, please refer to the article in Am Fam Physician from 2017. Patient information is available in the related handout on fainting. The author disclosed no relevant financial affiliations.

The table below provides information on different types of syncope, along with their associated scenarios and clinical features.
– **Cardiac syncope**:
– Arrhythmia, pacemaker dysfunction, channelopathies
– Typically sudden and unprovoked; may be preceded by palpitations
– Symptoms may include abnormal electrocardiographic findings, sudden onset of palpitations, and symptoms during or after exertion in certain positions
– **Neurally mediated (reflex) syncope**:
– Carotid sinus syndrome, situational syncope, vasovagal syncope
– Symptoms can be triggered by specific actions or stimuli
– Possible findings include ventricular pause or decreased blood pressure, prodromal symptoms, and precipitating factors
– **Orthostatic hypotension syncope**:
– Drug-induced, postural tachycardia syndrome, primary and secondary autonomic failure, volume depletion
– Symptoms related to changes in body position or medication use
– Factors contributing to his type of syncope include orthostatic hypotension, postural change, and dehydration
It is important to note that neurally mediated syncope is the most common type, accounting for approximately 45% of cases. On the other hand, cardiac syncope carries a higher mortality risk and is associated with cardiovascular disease. Orthostatic hypotension syncope affects about 10% of cases.
Furthermore, determining the urgency of evaluations for syncope cases is crucial to avoid unnecessary admissions and costs. Various risk stratification tools, such as the Boston Syncope Rule and the EGSYS score, can help identify high-risk patients and guide further assessment and management decisions.