History and Physical Examination

The history and physical examination are the most important components of the initial evaluation of syncope. Significant age and sex differences exist in the frequency of the various types of syncope. Syncope occurring in children and young adults is most frequently due to hyperventilation or vasovagal (vasodepressor) attacks and less frequently due to congenital heart disease (Lewis and Dhala, 1999). Fainting associated with benign tachycardias without underlying organic heart disease also may occur in children. Syncope due to basilar migraine is more common in young females. When repeated syncope begins in later life, organic disease of the cerebral circulation or cardiovascular system usually is responsible.

A careful history is the most important step in establishing the cause of syncope. The patient’s description usually establishes the diagnosis. The neurologist should always obtain as full a description as possible of the first faint. The clinical features should be established, with emphasis on precipitating factors, posture, type of onset of the faint (including whether it was abrupt or gradual), position of head and neck, the presence and duration of preceding and associated symptoms, duration of loss of consciousness, rate of recovery, and sequelae. If possible, question an observer about clonic movements, color changes, diaphoresis, pulse, respiration, urinary incontinence, and the nature of recovery.

Clues in the history that suggest cardiac syncope include a history of palpitations or a fluttering sensation in the chest before loss of consciousness. These symptoms are common in arrhythmias. In vasodepressor syncope and orthostatic hypotension, preceding symptoms of lightheadedness are common. Episodes of cardiac syncope generally are briefer than vasodepressor syncope, and the onset usually is rapid. Episodes due to cardiac arrhythmias occur independently of position, whereas in vasodepressor syncope and syncope due to orthostatic hypotension, the patient usually is standing.

Attacks of syncope precipitated by exertion suggest a cardiac etiology. Exercise may induce arrhythmic syncope or syncope due to decreased cardiac output secondary to blood flow obstruction, such as may occur with aortic or subaortic stenosis. Exercise syncope also may be due to cerebrovascular disease, aortic arch disease, congenital heart disease, pulseless disease (Takayasu disease), pulmonary hypertension, anemia, hypoxia, and hypoglycemia. A family history of sudden cardiac death, especially in females, suggests the long QT-interval syndrome. Postexercise syncope may be secondary to situational syncope or autonomic dysfunction. A careful and complete medical and medication history is mandatory to determine whether prescribed drugs have induced either orthostatic hypotension or cardiac arrhythmias. To avoid missing a significant cardiac disorder, consider a comprehensive cardiac evaluation in patients with exercise-related syncope.

The neurologist should inquire about the frequency of attacks of loss of consciousness and the presence of cerebrovascular or cardiovascular symptoms between episodes. Question the patient whether all episodes are similar, because some patients experience more than one type of attack. In the elderly, syncope may cause unexplained falls lacking prodromal symptoms. With an accurate description of the attacks and familiarity with clinical features of various types of syncope, the physician should correctly diagnose most patients (Brignole et al., 2006; Shen et al., 2004). Seizure types that must be distinguished from syncope include orbitofrontal complex partial seizures, which can be associated with autonomic changes, and complex partial seizures that are associated with sudden falls and altered awareness, followed by confusion and gradual recovery (temporal lobe syncope). Features that distinguish syncope from seizures and other alterations of consciousness are discussed later in the chapter.

After a complete history, the physical examination is of next importance. Examination during the episode is very informative but frequently impossible unless syncope is reproducible by a Valsalva maneuver or by recreating the circumstances of the attack, such as by position change. In the patient with suspected cardiac syncope, pay particular attention to the vital signs and determination of supine and erect blood pressure. Normally, with standing, the systolic blood pressure rises and the pulse rate may increase. An orthostatic drop in blood pressure greater than 15 mm Hg may suggest autonomic dysfunction. Assess blood pressure in both arms when suspecting cerebrovascular disease, subclavian steal, or Takayasu arteritis.

During syncope due to a cardiac arrhythmia, a heart rate faster than 140 beats per minute usually indicates an ectopic cardiac rhythm, whereas a bradycardia with heart rate of less than 40 beats per minute suggests complete atrioventricular (AV) block. Carotid sinus massage sometimes terminates a supraventricular tachycardia, but this maneuver is not advisable because of the risk of cerebral embolism from atheroma in the carotid artery wall. In contrast, a ventricular tachycardia shows no response to carotid sinus massage. Stokes-Adams attacks may be of longer duration and may be associated with audible atrial contraction and a first heart sound of variable intensity. Heart disease as a cause of syncope is more common in the elderly patient (Brady and Shen, 1999). The patient should undergo cardiac auscultation for the presence of cardiac murmurs and abnormalities of the heart sounds. Possible murmurs include aortic stenosis, subaortic stenosis, or mitral valve origin. An intermittent posture-related murmur may be associated with an atrial myxoma. A systolic click in a young person suggests mitral valve prolapse. A pericardial rub suggests pericarditis.

All patients should undergo observation of the carotid pulse and auscultation of the neck. The degree of aortic stenosis may be reflected at times in a delayed carotid upstroke. Carotid, ophthalmic, and supraclavicular bruits suggest underlying cerebrovascular disease. Carotid sinus massage may be useful in older patients suspected of having carotid sinus syncope, but it is important to keep in mind that up to 25% of asymptomatic persons may have some degree of carotid sinus hypersensitivity. Carotid massage should be avoided in patients with suspected cerebrovascular disease, and when performed, it should be done in properly controlled conditions with electrocardiographic (ECG) and blood pressure monitoring. The response to carotid massage is either vasodepressor, cardioinhibitory, or mixed.

Causes of Syncope

Investigations of Patients with Syncope

In the investigation of the patient with episodic impairment of consciousness, the diagnostic tests performed depend on the initial differential diagnosis (Kapoor, 2000). Individualize investigations, but some measurements such as hematocrit, blood glucose, and ECG are always appropriate. A resting ECG may reveal an abnormality of cardiac rhythm or the presence of underlying ischemic or congenital heart disease. In the patient suspected of cardiac syncope, a chest radiograph may show evidence of cardiac hypertrophy, valvular heart disease, or pulmonary hypertension. Other noninvasive investigations include radionuclide cardiac scanning, echocardiography, and prolonged Holter monitoring for the detection of cardiac arrhythmias. Echocardiography is useful in the diagnosis of valvular heart disease, cardiomyopathy, atrial myxoma, prosthetic valve dysfunction, pericardial effusion, aortic dissection, and congenital heart disease. Holter monitoring detects twice as many ECG abnormalities as those discovered on a routine ECG and may disclose an arrhythmia at the time of a syncopal episode. Holter monitoring typically for a 24-hour period is usual, although longer periods of recording may be required. Implantable loop recordings can provide long-term rhythm monitoring in patients suspected of having a cardiac arrhythmia (Krahn et al., 2004).

Exercise testing and electrophysiological studies are useful in selected patients. Exercise testing may be useful in detecting coronary artery disease, and exercise-related syncopal recordings may help localize the site of conduction disturbances. Consider tilt-table testing in patients with unexplained syncope in high-risk settings or with recurrent faints in the absence of heart disease (Kapoor, 1999). False positives occur, and 10% of healthy persons may faint. Tilt testing frequently employs pharmacological agents such as nitroglycerin or isoproterenol. The specificity of tilt-table testing is approximately 90%. In patients suspected to have syncope due to cerebrovascular causes, noninvasive diagnostic studies including Doppler flow studies of the cerebral vessels and magnetic resonance imaging (MRI) or magnetic resonance angiography may provide useful information. Cerebral angiography is sometimes useful. Electroencephalography (EEG) is useful in differentiating syncope from epileptic seizure disorders. An EEG should be obtained only when a seizure disorder is suspected and generally has a low diagnostic yield (Poliquin-Lasnier and Moore, 2009). A systematic evaluation can establish a definitive diagnosis in 98% of patients (Brignole et al., 2006). Neurally mediated (vasovagal or vasodepressor) syncope was found in 66% of patients, orthostatic hypotension in 10%, primary arrhythmias in 11%, and structural cardiopulmonary disease in 5%. Initial history, physical examination, and a standard ECG established a diagnosis in 50% of patients. A risk score such as the San Francisco Syncope Rule (SFSR) can help identify patients who need urgent referral. The presence of cardiac failure, anemia, abnormal ECG, or systolic hypotension helps identify these patients (Parry and Tan, 2010).

History and Physical Examination

The most definitive way to diagnose epilepsy and the type of seizure is clinical observation of the seizure, although this often is not possible, except when seizures are frequent. The history of an episode, as obtained from the patient and an observer, is of paramount importance. The neurologist should obtain a family history and should inquire about birth complications, central nervous system (CNS) infection, head trauma, and previous febrile seizures, because they all may have relevance.

The neurologist should obtain a complete description of the episode and inquire about any warning before the event, possible precipitating factors, and other neurological symptoms that may suggest an underlying structural cause. Important considerations are the age at onset, frequency, and diurnal variation of the events. Seizures generally are brief and have stereotypical patterns, as described previously. With complex partial seizures and tonic-clonic seizures, a period of postictal confusion is highly characteristic. Unlike some types of syncope, seizures are unrelated to posture and generally last longer. In a tonic-clonic seizure, cyanosis frequently is present, pallor is uncommon, and breathing may be stertorous.

Tonic-clonic and complex partial seizures may begin at any age from infancy to late adulthood, although young infants may not demonstrate the typical features because of incomplete development of the nervous system.

The neurological examination may reveal an underlying structural disturbance responsible for the seizure disorder. Birth-related trauma may result in asymmetries of physical development, cranial bruits may indicate an arteriovenous malformation, and space-occupying lesions may result in papilledema or in focal motor, sensory, or reflex signs. In the pediatric age group, mental retardation occurs in association with birth injury or metabolic defects. The skin should be examined for abnormal pigment changes and other dysmorphic features characteristic of some of the neurodegenerative disorders.

If examination is immediately after a suspected tonic-clonic seizure, the neurologist should search for abnormal signs such as focal motor weakness and reflex asymmetry and for pathological reflexes such as a Babinski sign. Such findings may help confirm that the attack was a seizure and suggest a possible lateralization or location of the seizure focus.

Absence Seizures

The onset of absence seizures is usually between the ages of 5 and 15 years, and a family history of seizures is present in 20% to 40% of patients. The absence seizure is a well-defined clinical and EEG event. The essential feature is an abrupt, brief episode of decreased awareness without any warning, aura, or postictal symptoms. At the onset of the absence seizure, there is an interruption of activity. A simple absence seizure is characterized clinically only by an alteration of consciousness. Characteristic of a complex absence seizure is an alteration of consciousness and other signs such as minor motor automatisms. During a simple absence seizure, the patient remains immobile, breathing is normal, skin color remains unchanged, postural tone is not lost, and no motor manifestations occur. After the seizure, the patient immediately resumes the previous activities and may be unaware of the attack. An absence seizure generally lasts 10 to 15 seconds, but it may be shorter or as long as 40 seconds.

Complex absence seizures have additional manifestations such as diminution of postural tone that may cause the patient to fall, an increase in postural tone, minor clonic movements of the facial musculature or extremities, minor face or extremity automatisms, or autonomic phenomena such as pallor, flushing, tachycardia, piloerection, mydriasis, or urinary incontinence.

If absence seizures are suspected, office diagnosis is frequently possible by having the patient hyperventilate for 3 to 4 minutes, which often induces an absence seizure.

Tonic-Clonic Seizures

The tonic-clonic seizure is the most dramatic manifestation of epilepsy and characterized by motor activity and loss of consciousness. Tonic-clonic seizures may be the only manifestation of epilepsy or may be associated with other seizure types. In a primary generalized tonic-clonic seizure, the affected person generally experiences no warning or aura, although a few myoclonic jerks may occur in some patients. The seizure begins with a tonic phase, during which there is sustained muscle contraction lasting 10 to 20 seconds. Following this phase is a clonic phase that lasts approximately 30 seconds and is characterized by recurrent muscle contractions. During a tonic-clonic seizure, a number of autonomic changes may be present, including an increase in blood pressure and heart rate, apnea, mydriasis, urinary or fecal incontinence, piloerection, cyanosis, and diaphoresis. Injury may result from a fall or tongue biting. In the postictal period, consciousness returns slowly, and the patient may remain lethargic and confused for a variable period. Pathological reflexes may be elicitable.

Some generalized motor seizures with transitory alteration of consciousness may have only tonic or only clonic components. Tonic seizures consist of an increase in muscle tone, and the alteration of consciousness generally is brief. Clonic seizures have a brief impairment of consciousness and bilateral clonic movements. Recovery may be rapid, but if the seizure is more prolonged, a postictal period of confusion may be noted.

Complex Partial Seizures

In a complex partial seizure, the first seizure manifestation may be an alteration of consciousness, but the patient frequently experiences an aura or warning symptom. The seizure may have a simple partial onset that may include motor, sensory, visceral, or psychic symptoms. The patient initially may experience hallucinations or illusions, affective symptoms such as fear or depression, cognitive symptoms such as a sense of depersonalization or unreality, or aphasia.

The complex partial seizure generally lasts 1 to 3 minutes but may be shorter or longer. It may become generalized and evolve into a tonic-clonic convulsion. During a complex partial seizure, automatisms, generally more complex than those in absence seizures, may occur. The automatisms may involve continuation of the patient’s activity before the onset of the seizure, or they may be new motor acts. Such new automatisms are variable but frequently consist of chewing or swallowing movements, lip smacking, grimacing, or automatisms of the extremities, including fumbling with objects, walking, or trying to stand up. Rarely, patients with complex partial seizures have drop attacks; in such cases, the term temporal lobe syncope often is used. The duration of the postictal period after a complex partial seizure is variable, with a gradual return to normal consciousness and normal response to external stimuli. Table 2.2 provides a comparison of absence seizures and complex partial seizures.

Table 2.2 Comparison of Absence and Complex Partial Seizures

Investigations of Seizures

In the initial investigations of the patient with tonic-clonic or complex partial seizures, perform a complete blood cell count, urinalysis, biochemical screening, and determinations of blood glucose level and serum calcium concentration. Laboratory investigations generally are not helpful in establishing a diagnosis of absence seizures. In infants and children, consider biochemical screening for amino acid disorders.

MRI is the imaging modality of choice for the investigation of patients with suspected seizures. It is superior to computed tomography and increases the yield of focal structural disturbances. Cerebrospinal fluid examination is not necessary in every patient with a seizure disorder and should be reserved for those in whom a recent seizure may relate to an acute CNS infection.

An EEG provides laboratory support for a clinical impression and helps classify the type of seizure. Epilepsy is a clinical diagnosis; therefore, an EEG study cannot confirm the diagnosis with certainty unless the patient has a clinical event during the recording. Normal findings on the EEG do not exclude epilepsy, and minor nonspecific abnormalities do not confirm epilepsy. Some patients with clinically documented seizures show no abnormality even after serial EEG recordings, sleep recordings, and special activation techniques. The EEG is most frequently helpful in the diagnosis of absence seizures. EEG supplemented with simultaneous video monitoring documents ictal events, allowing for a strict correlation between EEG changes and clinical manifestations. Simultaneous EEG and video monitoring also is useful in distinguishing epileptic seizures from nonepileptic phenomena.

In most patients, an accurate diagnosis requires only the clinical history and the foregoing investigations. Others present a diagnostic dilemma. A 24-hour ambulatory EEG recording differentiates an epileptic seizure from nonepileptic phenomena and also helps classify the specific type of seizure.

Psychogenic or Pseudoseizures (Nonepileptic Seizures)

Pseudoepileptic seizures are paroxysmal episodes of altered behavior that superficially resemble epileptic seizures but lack the expected EEG epileptic changes (Ettinger et al., 1999). However, as many as 40% of patients with pseudo- or nonepileptic seizures also experience true epileptic seizures.

A diagnosis often is difficult to establish based on the initial history alone. Establishing the correct diagnosis often requires observation of the patient’s clinical episodes, but complex partial seizures of frontal lobe origin may be difficult to distinguish from nonepileptic seizures. Nonepileptic seizures occur in children and adults and are more common in females. Most frequently, they superficially resemble tonic-clonic seizures. They generally are abrupt in onset, occur in the presence of other people, and do not occur during sleep. Motor activity is uncoordinated, but urinary incontinence and physical injury are uncommon. Nonepileptic seizures tend to be more prolonged than true tonic-clonic seizures. Pelvic thrusting is common. Ictal eye closing is common in nonepileptic seizures, whereas the eyes tend to be open in true epileptic seizures (Chung et al., 2006). During and immediately after the seizure, the patient may not respond to verbal or painful stimuli. Cyanosis does not occur, and focal neurological signs and pathological reflexes are absent.

In the patient with known epilepsy, consider the diagnosis of nonepileptic seizures when previously controlled seizures become medically refractory. The patient should undergo psychological assessments because most affected persons are found to have specific psychiatric disturbances. In this patient group, a high frequency of hysteria, depression, anxiety, somatoform disorders, dissociative disorders, and personality disturbances is recognized. A history of physical or sexual abuse is also more prevalent in nonepileptic seizure patients. At times, a secondary gain is identifiable. In some patients with psychogenic seizures, the clinical episodes frequently precipitate by suggestion and by certain clinical tests such as hyperventilation, photic stimulation, intravenous saline infusion, tactile (vibration) stimulation, or pinching the nose to induce apnea. Hyperventilation and photic stimulation also may induce true epileptic seizures, but their clinical features usually are distinctive. Some physicians avoid the use of placebo procedures, because this could have an adverse effect on the doctor-patient relationship (Parra et al., 1998).

Findings on the interictal EEG in patients with pseudoseizures are normal and remain normal during the clinical episode, demonstrating no evidence of a cerebral dysrhythmia. With the introduction of long-term ambulatory EEG monitoring, correlating the episodic behavior of a patient with the EEG tracing is possible, and psychogenic seizures are distinguishable from true epileptic seizures. Table 2.3 compares the features of psychogenic seizures with those of epileptic seizures.

Table 2.3 Comparison of Psychogenic and Epileptic Seizures

EEG, electroencephalogram.

As an auxiliary investigation of suspected psychogenic seizures, plasma prolactin concentrations may provide additional supportive data. Plasma prolactin concentrations frequently are elevated after tonic-clonic seizures, peaking in 15 to 20 minutes, and less frequently after complex partial seizures. Serum prolactin levels almost invariably are normal after psychogenic seizures, although such a finding does not exclude the diagnosis of true epileptic seizures (Chen et al., 2005). Elevated prolactin levels, however, also may be present after syncope and with the use of drugs such as antidepressants, estrogens, bromocriptine, ergots, phenothiazines, and antiepileptic drugs.

Although several procedures are employed to help distinguish epileptic from nonepileptic seizures, none of these procedures have both high sensitivity and high specificity. No procedure attains the reliability of EEG-video monitoring, which remains the standard diagnostic method for distinguishing between the two (Cuthill and Espie, 2005).