Syncope and vertigo

Clinical features

Patients with syncope are often completely asymptomatic by the time they arrive at hospital. A thorough history and physical examination is the key to finding the correct cause of the syncope. The history should focus on the patient’s recollection of the preceding and subsequent events, including environmental conditions, physical activity, prodromal symptoms and any intercurrent medical problems. Accounts from eyewitnesses or first responders are also vital. Medications that may impair autonomic reflexes must be scrutinized and a postural blood pressure measurement performed. Physical examination should concentrate on finding signs of structural heart disease as well as assessing any subsequent injuries.

Neurally mediated syncope causes a typical prodrome: patients complain of feeling light-headed and faint and often describe a blurring or ‘tunnelling’ of their vision. This may be accompanied by other vagally mediated symptoms, such as nausea or sweating. If patients are unable or unwilling to follow the body’s natural instincts to lie flat, they may collapse to the ground as they lose consciousness. This reflex brings the head level with the heart, resulting in an improvement in cerebral perfusion and a return to consciousness. During this time the patient may exhibit brief myoclonic movements, which can be mistaken for seizure activity but, in contrast with true epileptic seizures, there are no prolonged post-ictal symptoms. Fatigue is common following syncope.

Orthostatic hypotension occurs when the patient moves from a lying position to a sitting or standing position. If the required autonomic changes fail to compensate adequately, even healthy individuals will experience light-headedness or a blurring of vision and possibly loss of consciousness. The most vulnerable people are those with blunted or impaired autonomic reflexes, such as the elderly, those on certain medications (particularly vasodilators, antihypertensive agents and β-blockers) and those who are relatively volume-depleted due to heat, excessive fluid losses or inadequate oral intake.

Cardiac syncope is more likely to present with an absent or brief prodrome. Sudden unexplained loss of consciousness should raise suspicion for a cardiac arrhythmia, particularly in the high-risk patient. Both tachycardia and bradycardia can be responsible. A syncopal event while supine is of particular concern and a predictor of a cardiac cause. Syncopal events that occur during exertion should prompt a search for structural heart disease, in particular aortic stenosis.

Risk stratification

Most of the published literature on the assessment of patients presenting to EDs with syncope has focused on identifying risk factors for mortality or an adverse cardiac outcome. These assessments include a number of scores and clinical decision rules, such as the Osservatorio Epidemiologico sulla Sincope nel Lazio (OESIL) score and the San Francisco Syncope Rule (SFSR). Patients with syncope can be divided into high- and low-risk groups, as shown in Box 8.6.2 . Low-risk patients can be safely discharged for outpatient follow-up, but controversy over high-risk patients remains. It is likely that there is a significant proportion of patients in the high-risk group who actually have an intermediate risk and, given further evaluation in the ED or a short-stay unit, could also be safely discharged; however, it is more difficult to identify this subset.