59: Assessing Older Adults for Syncope Following a Fall

Falls and syncope are commonly encountered syndromes in older adults and both are associated with significant morbidity and mortality. It is often difficult to know when to consider syncope as the primary or a contributing cause to falls in older adults. This chapter provides some guidance for the clinician faced with the question, “Is this patient’s fall caused by syncope?”

Most studies estimate that one-third of community-dwelling older adults fall each year. Falls are the leading cause of injury among patients age 65 years and older. Twenty percent to 30% of falls among older adults result in moderate-to-severe injuries. Falls are associated with functional decline, increased risk for nursing home placement, decreased quality of life, and higher health care costs.

Syncope is also common among older adults. Its prevalence in the general population has a bimodal distribution peaking in people age 10–30 years and again in those older than age 65 years. Almost half of emergency room visits for syncope are made by persons 65 years of age or older. Because of underlying multiple comorbidities and increased prevalence of cardiovascular disease in older people, the morbidity and mortality associated with syncope is higher in older adults compared to younger adults.

Falls

The literature varies widely on the definition of falls, but typically falls are defined as unintentionally coming to rest on the ground or a lower surface. When evaluating a patient with falls, obtaining a detailed history of the fall from the patient and witnesses, if available, is imperative and a good starting point. This history should include the circumstances surrounding the fall, any preceding symptoms, such as dizziness or lightheadedness, whether the fall was witnessed or not, and whether there was loss of consciousness with the fall. A focused physical exam including a cognitive and functional assessment should also be completed. During the evaluation, it is important to remember that falls constitute a geriatric syndrome. As such, the cause of falling in an older patient is rarely the result of a single cause but instead the result of a complex interaction between intrinsic and extrinsic risk factors. In addition to a detailed history and physical exam, identifying and addressing these risk factors is at the core of a falls evaluation. Current guidelines emphasize assessing the following risk factors: (a) history of falls, (b) medications, (c) gait, balance, and mobility, (d) visual acuity, (e) other neurologic impairments, (f) muscle strength, (g) heart rate and rhythm, (h) postural hypotension, (i) feet and footwear, and (j) assessment of environmental hazards (Table 59–1). Medication classes to specifically identify in older adults with falls include anticonvulsants, antipsychotics, benzodiazepines, nonbenzodiazepine hypnotics, tricyclic antidepressants, and selective serotonin reuptake inhibitors. Because of their propensity to worsen postural hypotension, antihypertensive medications should also be evaluated.

Syncope

Fainting is a common problem and encompasses any disorder associated with a real or perceived transient loss of consciousness. Nontraumatic transient loss of consciousness is further classified into syncope, epileptic disorders, psychogenic pseudosyncope, and rare miscellaneous causes, such as cataplexy or drop attacks. Syncope specifically refers to transient loss of consciousness caused by global hypoperfusion. Hallmark features of its presentation are sudden loss of consciousness with associated loss of postural tone and rapid spontaneous recovery. The causes of syncope can be classified into 3 broad categories: reflex-mediated syncope, syncope caused by orthostatic hypotension, and cardiac syncope (Table 59–2).

The initial goal of the evaluation of syncope is risk stratification, that is, to define those patients who warrant urgent cardiac evaluation because of the high short-term risk of recurrence of syncope. Approximately one-third of patients with syncope will have a recurrent event within 3 years. As with falls, the evaluation of the patient with syncope should start with obtaining a comprehensive history of the event and physical examination, including checking orthostatic vital signs. An electrocardiogram (ECG) should also be performed. Historical questions should be targeted to try to identify which class of syncope is most likely. A detailed history and physical examination combined with ECG findings can identify the cause of syncope in nearly 25% of patients. Patients in whom the cause of syncope is uncertain may warrant additional tests. These tests include, but are not limited to, echocardiography, stress testing, short-term or long-term ECG monitoring, electrophysiology study, tilt-table testing, and supine and upright carotid sinus massage. Similar to falls, older adults may have more than 1 factor contributing to their syncope. Physiologic changes associated with aging, such as inability to preserve sodium and water, decreased baroreceptor responsiveness and autonomic dysfunction all increase older adults’ risk for syncope. The use of multiple medications that affect blood pressure, heart rate, and volume status, such as diuretics and β blockers, also predispose older people to syncope. All of these factors should be kept in mind when evaluating the older adult with syncope.

There is increasing evidence of an overlap between non-accidental falls and syncope. First, because of the lack of a witness account, history provided by the patient may be unreliable. In addition to patients not recalling the circumstances of their fall, several studies indicate patients do not accurately remember the number of falls they have. Individual patient factors that increase the risk of poor fall recall include older age, cognitive impairment, and occurrence of a non-injurious fall. Second, patients may not recall loss of consciousness. Retrograde amnesia for loss of consciousness affects up to 30% of patients with syncope. These data mainly originate from studies evaluating patients with carotid sinus syndrome, although up to two-thirds of patients with orthostatic hypotension may also not report loss of consciousness. Finally, in patients with gait or balance problems, hypotension and bradycardia may be less-well tolerated, resulting in a fall. Both hypotension and bradycardia can decrease cardiac output enough to cause cerebral hypoperfusion and loss of postural tone without causing complete loss of consciousness. These patients may be misclassified as having only suffered a fall and not a syncopal event. Yet, the underlying physiology is the same (decreased global cerebral perfusion) and may be treatable, warranting consideration of syncope in these patients.

Clinicians should consider evaluating patients for syncope when the following factors are present: (a) history of loss of consciousness with the fall, (b) unexplained non-accidental fall or (c) recurrent falls despite adherence to a multi-factorial targeted treatment program (Table 59–3).

There are 3 diagnostic categories to consider in the differential diagnoses of these patients: orthostatic hypotension and its variants, carotid sinus syndrome, and cardiac syncope due to arrhythmia (see Table 59–3).

Orthostatic Hypotension and Its Variants

Classical Orthostatic Hypotension

Classical orthostatic hypotension, defined as a drop in systolic blood pressure of ≥20 mm Hg within 3 minutes of standing, is common in older adults. However, it is often not tested for or may be simply disregarded by patients. In the Cardiovascular Health Study, the prevalence of orthostatic hypotension was 18% in subjects age 65 years or older, yet only 2% of these subjects reported symptoms with standing.

Delayed Orthostatic Hypotension

Delayed orthostatic hypotension is characterized by a drop in systolic blood pressure of ≥20 mm Hg after more than 3 minutes of standing. It should be considered in older adults with underlying neurologic disorders, which put them at risk for autonomic dysfunction. These include idiopathic Parkinson disease, multiple system atrophy, and diabetes. Because nearly 40% of patients with this condition will drop their blood pressure only after at least 10 minutes of upright posture, tilt-table testing is typically used to evaluate for delayed orthostatic hypotension.

Postprandial Hypotension

Postprandial hypotension is another diagnosis to consider when evaluating patients with falls for the possibility of syncope. Postprandial hypotension is defined as a fall in systolic blood pressure of ≥20 mm Hg within 2 hours of eating a meal. Nearly half of healthy older patients with unexplained syncope have been found to have postprandial hypotension. Patients with classical orthostatic hypotension or autonomic dysfunction are also at higher risk for postprandial hypotension. Obtaining a detailed history of events and their association with meals can help identify patients with possible postprandial hypotension. Some patients may require 24-hour ambulatory blood pressure monitoring to confirm the diagnosis.

Carotid Sinus Syndrome

Carotid sinus hypersensitivity is caused by an exaggerated response to carotid sinus massage. In some studies, up to 70% of patients ≥65 years old with unexplained falls have carotid sinus hypersensitivity during supine and upright tilt-table testing. Carotid sinus syndrome is diagnosed when there is reproduction of a patient’s symptoms associated with a systolic blood pressure drop of ≥50 mm Hg (vasodepressor response), an asystolic pause of ≥3 seconds (cardioinhibitory response), or both (mixed response) with carotid sinus massage. Carotid sinus syndrome has been reported to be the cause of unexplained falls in up to 40% of patients. Performing carotid sinus massage in the supine and upright positions increases the sensitivity. Although the evidence is not yet conclusive, permanent cardiac pacing may be helpful in reducing falls in patients with a marked cardioinhibitory response to carotid sinus massage.

Cardiac Syncope Caused by Arrhythmia

Cardiac syncope caused by arrhythmia may be responsible for up to 30% of syncope in older adults. Its high prevalence in older adults is thought to be related to the increased number of underlying cardiovascular comorbidities older adults have as well as the increased prevalence of sinus node dysfunction seen with aging. Atrial fibrillation, one manifestation of sinus node dysfunction, has been found to be an independent risk factor for unexplained non-accidental falls in older adults. Ambulatory ECG monitoring can be used to diagnose syncope caused by arrhythmia. This is often done by using a 30-day event monitor. However, because cardiac syncope caused by arrhythmia may not recur within 30 days, clinical guidelines endorse the use of long-term ECG monitoring with implantable loop recorders for patients with unexplained syncope. Recognizing the overlap between syncope and falls, one may also consider long-term ECG monitoring in a patient with unexplained falls.

When evaluating an older adult who has fallen or with frequent falls, it is important to: (a) conduct a multifactorial fall risk assessment (see Table 59–1); (b) consider clinical scenarios in which syncope may be the cause of falls (see Table 59–3); and (c) if syncope is the likely cause of the fall, classify syncope to determine next diagnostic and treatment steps (see Table 59–2).