Episodic Impairment of Consciousness PDF

2 Episodic Impairment of Consciousness Daniel Winkel, Dimitri Cassimatis OUTLINE Syncope, 8 Seizure Classification, 14 History and Physical Examination, 9 Absence Seizures, 14...

2 Episodic Impairment of Consciousness Daniel Winkel, Dimitri Cassimatis OUTLINE Syncope, 8 History and Physical Examination, 9 Causes of Syncope, 10 Investigations of Patients with Syncope, 13 Seizures, 14 Pathophysiology, 14 History and Physical Examination, 14 Temporary loss of consciousness may be caused by transient impaired cerebral perfusion (the presumed mechanism for syncope), cerebral ischemia, migraine, epileptic seizures, metabolic disturbances, sudden increases in intracranial pressure (ICP), or sleep disorders. These con- ditions may be difficult to distinguish from anxiety attacks, psycho- genic nonepileptic spells (PNESs), panic disorder, and malingering, which should always be considered. Syncope is defined as an abrupt, transient, complete loss of con- sciousness, associated with inability to maintain postural tone, with rapid and spontaneous recovery (Shen et al., 2017). Syncope may result from both cardiac and noncardiac causes. Specific causes of a transient impairment in cerebral perfusion include vasovagal episodes (typically a surge in parasympathetic autonomic tone), decreased car- diac output secondary to cardiac arrhythmias, outflow obstruction, hypovolemia, orthostatic hypotension, and decreased venous return. Cerebrovascular disturbances from transient ischemic attacks of the posterior cerebral circulation perfusing the brainstem, or cerebral vasospasm from migraine, subarachnoid hemorrhage, or hyperten- sive encephalopathy may result in temporary loss of consciousness. Situational syncope may occur in association with cough, micturition, defecation, swallowing, Valsalva maneuver, or diving. These spells are often mediated via a decrease in venous return to the thorax and/or an increase in sympathetic tone. Metabolic disturbances due to hypoxia, drugs, anemia, and hypoglycemia may result in frank syncope or, more frequently, the sensation of an impending faint (presyncope). Absence seizures, generalized tonic-clonic seizures, and complex partial seizures are associated with alterations of consciousness and are usually easily distinguished from syncope by careful questioning. Seizures may be difficult to distinguish from PNESs, panic attacks, and malingering. In children, breath-holding spells, a form of syncope (dis- cussed later under “Miscellaneous Causes of Altered Consciousness”), can cause a transitory alteration of consciousness that may mimic epileptic seizures in this population. Although rapid increases in ICP (which may result from intermittent hydrocephalus, severe head trauma, brain tumors, intracerebral hemorrhage, certain severe met- abolic derangements or Reye syndrome) may produce sudden loss of consciousness, affected patients frequently have other neurological manifestations that lead to this diagnosis. 8 @ @ @ D D D D TABLE 2.1 Comparison of Clinical Features of Features Syncope Relation to posture Common Time of day Diurnal Precipitating factors Emotion, injury, coughing, micturition, Skin color Pallor Diaphoresis Common Aura or premonitory symptoms Often minutes or Convulsion Rare Other abnormal movements Minor irregular twitching Injury Rare Urinary incontinence Rare Tongue biting No Postictal confusion Rare Postictal headache No Focal neurological signs No Cardiovascular signs Common to have cardiovascular unless there Abnormal findings on EEG Rare (generalized EEG, Electroencephalogram. BOX 2.1 Classification and Etiology of Syncope Arrhythmias: Bradyarrhythmias Tachyarrhythmias Reflex arrhythmias (temporary sinus pause or bradycardia) Decreased cardiac output: Outflow obstruction Inflow obstruction Cardiomyopathy Hypovolemic Hypotensive: Vasovagal attack Drugs Dysautonomia Cerebrovascular: Carotid disease Vertebrobasilar disease Vasospasm Takayasu disease Metabolic: Hypoglycemia Anemia Anoxia Hyperventilation Multifactorial: Vasovagal (vasodepressor) attack Cardiac syncope Situational: cough, micturition, defecation, swallowing, maneuver have a genetic component suggestive of autosomal dominant inher- itance (Klein et al., 2013). Wieling et al. (2009) reviewed the clinical features of the successive phases of syncope, as discussed earlier. @ @ @ D D D D 10 PART I Common Neurological Problems preceding symptoms of lightheadedness are common. Episodes of car- diac syncope generally are briefer than vasodepressor syncope, and the onset usually is rapid. Episodes due to cardiac arrhythmias occur inde- pendently 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 eti- ology. Exercise may induce arrhythmic syncope or syncope due to decreased cardiac output secondary to blood flow obstruction, such as may occur with hypertrophic cardiomyopathy with dynamic outflow obstruction, or with aortic or subaortic stenosis. Exercise syncope also may be due to cerebrovascular disease, aortic arch disease, congeni- tal heart disease, severe stenosis of any of the cardiac valves, pulseless disease (Takayasu disease, a type of vasculitis), pulmonary hyperten- sion, anemia, hypoxia, and hypoglycemia. A family history of sudden cardiac death, especially in females, suggests the long QT syndrome. Postexercise syncope may be secondary to orthostasis in the setting of dilated vascular beds in the large muscles (cardiac output may normal- ize faster than systemic vascular resistance), vasovagal syncope brought on by relative hypovolemia (in a setting of dilated vasculature), or autonomic dysfunction. A careful and complete medical and med- ication history is mandatory to determine whether prescribed drugs have induced either orthostatic hypotension or cardiac arrhythmias. To avoid missing a significant cardiac disorder, one should always consider a comprehensive cardiac evaluation in patients with exer- cise-related syncope. Particularly in the elderly, cardiac syncope must be distinguished from more benign causes because of increased risk of sudden cardiac death (Anderson and O’Callaghan, 2012). The neurologist should inquire about the frequency of attacks of loss of consciousness and the presence of cerebrovascular or cardio- vascular 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 lack- ing prodromal symptoms. With an accurate description of the attacks and familiarity with clinical features of various types of syncope, the physician will correctly diagnose most patients (Brignole et al., 2006; Shen et al., 2004), but confirmatory testing to rule in, or to exclude, some high-risk diagnoses may be required. Features that distinguish syncope from seizures and other alterations of consciousness are dis- cussed 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 pres- sure is stable or 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 cere- brovascular disease, subclavian steal, or Takayasu arteritis. During syncope due to a cardiac arrhythmia, a heart rate faster than 140 beats/ min often indicates that the rhythm is not sinus tachycardia (may be a supraventricular tachycardia, an ectopic atrial or ventricular tachycardia, or atrial fibrillation or flutter), whereas a bradycardia with heart rate of less than 40 beats/min suggests complete atrioventricu- lar (AV) block or a prolonged sinus pause. An irregular pulse indicates possible atrial fibrillation but may also be seen with frequent prema- ture atrial or ventricular contractions, and with intermittent AV block. Vagal maneuvers, which include Valsalva and cold water to the face, sometimes terminate a supraventricular tachycardia. Carotid sinus massage may also be effective, but this maneuver is not advisable in the acute setting because of the risk of cerebral embolism from potential @ @ @ D D D D of consciousness occurring in association with a complete AV block. Complete AV block occurs primarily in elderly patients and is often also seen in patients with a history of aortic valve disease. The onset of a Stokes-Adams attack generally is sudden, although a number of visual, sensory, and perceptual premonitory symptoms may be expe- rienced. During the syncopal attack, the pulse disappears and no heart sounds are audible. The patient is pale and, if standing, falls down, often with resultant injury. If the attack is sufficiently prolonged, res- piration may become labored, and urinary incontinence and clonic muscle jerks may occur. Prolonged confusion and neurological signs of cerebral ischemia may be present. Regaining of consciousness gen- erally is rapid. The clinical features of complete AV block include a slow pulse and elevation of the jugular venous pressure, sometimes with cannon waves. The first heart sound is of variable intensity, and heart sounds related to atrial contractions may be audible. An ECG confirming the diagnosis demonstrates independence of atrial P waves and ventricular QRS com- plexes. During Stokes-Adams attacks, the ECG generally shows ventric- ular standstill or a very slow ventricular escape rhythm, but ventricular fibrillation or tachycardia also may occur. Sinoatrial Block SA block may result in dizziness, lightheadedness, and syncope. It is most frequent in the elderly. Palpitations are common, and the patient appears pale. Patients with SA node dysfunction frequently have other conduction disturbances, and certain drugs (e.g., verapamil, digoxin, beta-blockers) may further impair SA node function. On examination, the patient’s pulse may be regular between attacks. During an attack, the pulse may be slow or irregular, and any of a number of rhythm disturbances may be present. Paroxysmal Tachycardia Supraventricular tachycardias include atrial fibrillation with a rapid ventricular response, atrial flutter, AV nodal reentry, and the Wolff- Parkinson-White syndrome (AV reentry involving an accessory path- way). These arrhythmias may suddenly reduce cardiac output enough to cause syncope. Ventricular tachycardia may result in syncope if the heart rate is sufficiently fast, and ventricular fibrillation will almost always result in nearly immediate syncope. Ventricular arrhythmias are more likely in the elderly and in patients with cardiac disease. Ventricular fibrillation may be part of the long QT syndrome, which has a cardiac-only phenotype or may be associated with congenital sen- sorineural deafness in children. In most patients with this syndrome, episodes begin in the first decade of life, but onset may be much later. Exercise may precipitate an episode of cardiac syncope. Long QT syn- drome may be congenital or acquired and sometimes is misdiagnosed in adults as epilepsy. Acquired causes include cardiac ischemia, mitral valve prolapse, myocarditis, and electrolyte disturbances; there are also many drugs that can prolong the QT. In the short QT syndrome, signs and symptoms are highly variable, ranging from complete absence of clinical manifestations to recurrent syncope to sudden death. The age at onset often is young, and affected persons frequently are otherwise healthy. A family history of sudden death in a patient with a short QT may indicate a familial short QT syndrome inherited as an autosomal dominant mutation. The ECG demonstrates a short QT interval and a tall and peaked T wave, and electrophysiological studies may induce ventricular fibrillation. Brugada syndrome may produce syncope as a result of ventricular tachycardia or ventricular fibrillation (Brugada et al., 2000). The ECG in Brugada syndrome may or may not show a typical Brugada pattern at rest (i.e., an incomplete right bundle-branch block in leads V1 and V2 and significant downsloping ST elevation leading to inverted T waves in those two leads). @ @ @ D D D D 12 PART I Common Neurological Problems cardiac tamponade. Patients may also inadvertently cause reduced venous return and hypotension during a prolonged coughing fit or breath hold. Syncope associated with aortic dissection may be due to cardiac tamponade but also may be secondary to hypotension, obstruction of cerebral circulation, or a cardiac arrhythmia. Hypovolemia Acute blood loss, usually due to GI tract bleeding, may cause weakness, faintness, and syncope if sufficient blood is lost. Blood volume deple- tion by dehydration may cause faintness and weakness, but true syn- cope is uncommon except when combining dehydration and exercise. Both anemia and hypovolemia may predispose a patient to vasovagal symptoms and vasovagal syncope when standing upright. Hypotension Several conditions cause syncope by producing a fall in arterial pres- sure. Cardiac causes were discussed earlier. The common faint (syn- onymous with vasovagal or vasodepressor syncope) is the most frequent cause of a transitory fall in blood pressure resulting in syncope. It often is recurrent, tends to occur in relation to emotional stimuli, and may affect 20%–25% of young people. Less commonly, it occurs in older patients with cardiovascular disease. The common faint may or may not be associated with bradycar- dia. The patient experiences impairment of consciousness, with loss of postural tone. Acutely, signs of autonomic hyperactivity are common, including pallor, diaphoresis, nausea, and dilated pupils. After recov- ery, patients may have persistent pallor, sweating, and nausea; if they get up too quickly, they may black out again. Presyncopal symptoms of lethargy and fatigue, nausea, weakness, a sensation of an impending faint, yawning, ringing in the ears, and blurred or tunnel vision may occur. It is more likely to occur in certain circumstances such as in a hot crowded room, especially if the affected person is volume-depleted and standing for a prolonged period, although it may still occur when sitting upright. Venipuncture, the sight of blood, or a sudden painful or traumatic experience may precipitate syncope. When the patient regains consciousness, there usually is no confusion or headache, although weakness is frequent. As in other causes of syncope, if the period of cerebral hypoperfusion is prolonged, urinary incontinence and a few clonic movements may occur (convulsive syncope). Orthostatic syncope occurs when autonomic factors that com- pensate for the upright posture are inadequate. This can result from a variety of clinical disorders. Blood volume depletion or venous pool- ing may cause syncope when the affected person assumes an upright posture. Orthostatic hypotension resulting in syncope also may occur with drugs that impair sympathetic nervous system function. Diuretics, antihypertensive medications, nitrates, arterial vasodilators, sildenafil, calcium channel blockers, monoamine oxidase inhibitors, phenothiazines, opiates, l-dopa, alcohol, and tricyclic antidepressants all may cause orthostatic hypotension. Patients with postural ortho- static tachycardia syndrome (POTS) frequently experience ortho- static symptoms without orthostatic hypotension, but syncope can occur occasionally. Data suggest that there is sympathetic activation in this syndrome (Garland et al., 2007). Autonomic nervous system dysfunction resulting in syncope due to orthostatic hypotension may be a result of primary autonomic failure due to Shy-Drager syndrome (multiple system atrophy) or Riley-Day syndrome. Neuropathies that affect the autonomic nervous system include those of diabetes mellitus, amyloidosis, Guillain-Barré syndrome, acquired immunodeficiency syndrome (AIDS), chronic alcoholism, hepatic porphyria, beriberi, autoimmune subacute autonomic neuropathy, and small fiber neu- ropathies. Rarely, subacute combined degeneration, syringomyelia, and other spinal cord lesions may damage the descending sympathetic @ @ @ D D D D with chronic anemia or certain hemoglobinopathies that impair oxygen transport, similar symptoms may occur. Syncopal symptoms may be more prominent with exercise or physical activity. Hyperventilation-induced syncope usually has a psychogenic ori- gin. During hyperventilation, the patient may experience paresthesia of the face, hands, and feet, a buzzing sensation in the head, lighthead- edness, giddiness, blurring of vision, mouth dryness, and occasionally tetany. Patients often complain of tightness in the chest and a sense of panic. Symptoms can occur in the supine or erect position and are gradual in onset. Rebreathing into a paper bag relieves the symptoms. During hyperventilation, a tachycardia may be present, but blood pressure generally remains normal. Miscellaneous Causes of Syncope More than one mechanism may be responsible in certain types of syn- cope. Both vasodepressor and cardioinhibitory factors may be oper- ational in common presentations of vasovagal syncope. In cardiac syncope, a reduction of cardiac output may be due to a single cause such as obstruction to inflow or outflow or a cardiac arrhythmia, but multiple factors are frequent. Situational syncope, such as is associated with cough (tussive syn- cope) and micturition, are special cases of reflex syncope. In cough syn- cope, loss of consciousness occurs after a paroxysm of severe coughing. This is most likely to occur in obese men, usually smokers or patients with chronic bronchitis. The syncopal episodes occur suddenly, gener- ally after repeated coughing but occasionally after a single cough. Before losing consciousness, the patient may feel lightheaded. The face often becomes flushed secondary to congestion, and then pale. Diaphoresis may be present, and loss of muscle tone may occur. Syncope gener- ally is brief, lasting only seconds, and recovery is rapid. Several factors probably are operational in causing cough syncope. The most signif- icant is blockage of venous return by raised intrathoracic pressure. In weight-lifting syncope, a similar mechanism is operational. Micturition syncope most commonly occurs in men during or after micturition, usually after arising from bed in the middle of the night to urinate in the erect position. There may be a history of drinking alcohol before going to bed. The syncope may result from sudden reflex periph- eral vasodilatation caused by the release of intravesicular pressure and bradycardia. The relative peripheral vasodilatation from recent alcohol use and a supine sleeping position is contributory because blood pres- sure is lowest in the middle of the night. The syncopal propensity may increase with fever. Rarely, micturition syncope with headache may result from a pheochromocytoma in the bladder wall. Defecation syn- cope is uncommon, but it probably shares the underlying pathophys- iological mechanisms responsible for micturition syncope. Convulsive syncope is an episode of syncope of any cause that is sufficiently pro- longed to result in a few clonic jerks; the other features typically are syncopal and should not be confused with epileptic seizures. Other causes of situational syncope include diving and the postprandial state. Syncope during sexual activity may be due to neurocardiogenic syncope, coronary artery disease, or the use of erectile dysfunction medications. Rare intracranial causes of syncope include intermittent obstruction to cerebrospinal fluid (CSF) flow such as with a third ventricular mass. Rarely, syncope can occur with Arnold-Chiari malformations, but these patients usually have other symptoms of brainstem dysfunction. Investigations of Patients with Syncope In the investigation of the patient with episodic impairment of con- sciousness, the diagnostic tests performed depend on the initial dif- ferential diagnosis. It is best to individualize investigations, but some measurements such as hematocrit, blood glucose, and ECG are always appropriate. A resting ECG may reveal an abnormality of cardiac @ @ @ D D D D 14 PART I Common Neurological Problems In summary, the initial and most important parts of the evaluation of a patient with syncope are a detailed history from the patient and any witnesses of the syncopal event, followed by a thorough physical exam- ination with a focus on the neurological and cardiovascular findings. It is recommended that all patients receive an ECG as part of an initial syncope evaluation. It is reasonable for most patients to undergo at least limited laboratory testing in the acute setting to rule out anemia and hypoglyce- mia. Beyond this, imaging and laboratory testing should be individualized and may not be necessary if the history and physical are highly sugges- tive of vasovagal syncope and if the exam and ECG show no concerning findings. In 2017 the American College of Cardiology, American Heart Association, and the Heart Rhythm Society released a joint guideline on the evaluation and management of patients with syncope that may fur- ther guide the clinician in the care of these patients (Shen et al., 2017). SEIZURES Seizures can cause sudden, unexplained loss of consciousness in a child or an adult (see Chapter 100). Seizures and syncope are distinguishab clinically, and one should be familiar with the pathophysiology and clinical features for both. Pathophysiology Epilepsy is the syndrome of recurrent unprovoked seizures. It is broadly dichotomized into generalized and partial (also known as focal). Generalized epilepsies are characterized by seizures both hemispheres at onset rather than by electrographic spread. They are typically genetically predisposed and tend to manifest in child- hood and adolescence in the form of discrete epilepsy syndromes (e.g., childhood absence epilepsy, juvenile myoclonic epilepsy). In contrast, partial or focal epilepsies are characterized by focal-onset seizures that may or may not secondarily generalize (i.e., propagate to various parts of the brain). These are often termed “localization related” or symp- tomatic due to the known local pathology (e.g., tumor, gliosis, abscess) that serves as an epileptogenic focus. If the pathology is suspected but not visualized, the term cryptogenic is instead used. History and Physical Examination The most definitive way to diagnose epilepsy and the seizure type is clin- ical 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 neurolo- gist should obtain a family history and should inquire about birth com- plications, 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 epi- sode and inquire about any warning before the event, possible precip- itating 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 gener- ally 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 and is much slower to resolve than the typical postsyncopal confusion. 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 uncom- mon, and breathing may be stertorous. In children with autonomic seizures (Panayiotopoulos syndrome) syncope-like epileptic seizures can occur, although usually accompanied by other features that help to clarify the diagnosis (Koutroumanidis et al., 2012). Tonic-clonic and complex partial seizures may begin at any age, although young infants may not demonstrate the typical features because @ @ @ D D D D characterized by recurrent synchronous muscle contractions or rhyth- mic jerking. 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, shoulder dislo- cation, or tongue biting. In the postictal period, consciousness returns quite slowly, and the patient may remain lethargic and confused for a variable period. The patient may remain somnolent and wish to sleep for many hours. Pathologically brisk reflexes may be elicitable. Some generalized motor seizures with transitory alteration of con- sciousness 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 impair- ment 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, affec- tive symptoms such as fear or depression, cognitive symptoms such as a sense of depersonalization or unreality, or aphasia. The particular symptoms are tightly correlated to the neuroanatomy of the seizure onset zone and eventually the extent of propagation. The complex partial seizure generally lasts 1–2 minutes but may be shorter or longer. If it propagates widely, it may become secondarily generalized and evolve into a tonic-clonic convulsion. During a com- plex partial seizure, automatisms, generally more complex than those in absence seizures, may occur. The automatisms may involve continua- tion of the patient’s activity before the onset of the seizure, or they may be new motor acts. Such automatisms are variable but frequently con- sist of oral automatisms (chewing or swallowing movements, lip smack- ing) or automatisms of the extremities, including fumbling with objects, walking, or trying to stand up. 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 pro- vides a comparison of absence seizures and complex partial seizures. Investigations of Seizures In the initial investigations of the patient with tonic-clonic or complex partial seizures, one should perform a complete blood cell count, uri- nalysis, biochemical screening, and determinations of blood glucose level and serum calcium concentration. Laboratory investigations gen- erally are not helpful in establishing a diagnosis of absence seizures. In infants and children, consider biochemical screening for amino acid disorders. CSF 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. MRI is the imaging modality of choice for the investigation of patients with suspected seizures. It is superior to computed tomogra- phy and increases the yield of focal structural disturbances. EEG provides laboratory support for a clinical impression and helps to classify the type of seizure. Epilepsy is a clinical diagnosis; therefore an EEG 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 or prolonged EEG recordings, including with special activation techniques. The EEG is most frequently helpful @ @ @ D D D D 16 PART I Common Neurological Problems diagnosis can be distinguished from syncope if tilt-table testing fails to document a decrease in heart rate or blood pressure. In the patient with known epilepsy, consider the diagnosis leptic spells when previously controlled seizures become medically refrac- tory. 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, soma- toform disorders, dissociative disorders, and personality disturbances is recognized. A history of physical or sexual abuse is also more prevalent in patients with PNESs. At times, a secondary gain is identifiable, although the absence of an identified gain or trigger should not preclude the diag- nosis. In some patients with PNESs, the clinical episodes frequently pre- cipitate by suggestion, by certain clinical tests such as hyperventilation and photic stimulation, and by placebo procedures such as intravenous saline infusion, tactile (vibration) stimulation, or pinching the nose to induce apnea. Hyperventilation and photic stimulation also may induce epileptic seizures, but their clinical features usually are distinctive. Some physicians avoid the use of placebo procedures because of the potential for an adverse effect on the doctor-patient relationship (Parra et al., 1998). Findings on the EEG in patients with PNESs are normal during the clinical episode, demonstrating no evidence of an ictal process. However, it is important to note that a number of organic conditions may present with similar behavioral and motor symptoms and a nonepileptiform EEG (Caplan et al., 2011). These may include conditions such as frontal lobe seizures, limb-shaking transient ischemic attacks, and paroxysmal dyskinesias, and a careful clinical history and adjunct testing are para- mount. With the introduction of long-term ambulatory EEG monitor- ing, correlating the episodic behavior of a patient with the EEG tracing is possible, and PNESs are distinguishable from epileptic seizures. Table 2.3 compares the features of PNES with those of epileptic seizures. Although several procedures are used to help distinguish epileptic seizures from PNESs, none of these procedures have both high sensi- tivity 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 Espire, 2005). MISCELLANEOUS CAUSES OF ALTERED CONSCIOUSNESS In children, alteration of consciousness may accompany breath-hold- ing spells and metabolic disturbances. Breath-holding spells and sei- zures are easily distinguished. Most spells start at 6–28 months of age, but they may occur as early as the first month of life; they usually dis- appear by 5 or 6 years of age. Breath-holding spells may occur several times per day and appear as either cyanosis or pallor. The trigger for cyanotic breath-holding spells is usually a sudden injury or fright, anger, or frustration. The child initially is provoked, cries vigorously for a few breaths, and stops breathing in expiration, whereupon cyanosis rapidly develops. Consciousness is lost because of hypoxia. Although stiffening, a few clonic movements, and urinary incontinence occasionally are observed, these episodes can be clearly distinguished from epileptic seizures by the history of provocation and by noting that the apnea and cyanosis occur before any alteration of consciousness. In these children, findings on the neurological exam- ination and the EEG are normal. The provocation for pallid breath-holding is often a mild painful injury or a startle. The infant cries initially and then becomes pale and loses consciousness. As in the cyanotic type, stiffening, clonic move- ments, and urinary incontinence may rarely occur. In the pallid infant syndrome, loss of consciousness is secondary to excessive vagal tone, resulting in bradycardia and subsequent cerebral ischemia, as in a vasovagal attack. @ @ @ D D D D OUTLINE Falls and Drop Attacks—Introduction, 17 Drop Attacks With Loss of Consciousness, 17 Syncope, 17 Seizures, 18 Drop Attacks Without Loss of Consciousness, 18 Transient Ischemic Attacks, 18 Third Ventricular and Posterior Fossa Abnormalities, 18 Otolith Crisis, 19 FALLS AND DROP ATTACKS—INTRODUCTION Falling in childhood is part of growing up and usually medically insig- nificant, unless a serious childhood illness contributes. With advanc- ing age, the potential for injury and other complications increases, and falling eventually develops into a dangerous burden for the elderly and the neurologically impaired. Quality of life can be severely affected by associated morbidity, immobilization, fear of falling (FOF), and grow- ing dependency. Despite improved understanding of falls and their prevention, they remain a leading public health problem. The 2014 Behavioral Risk Factor Surveillance System (BRFSS) estimated that more than a fourth of adults older than 65 years have fallen, resulting in 29 million annual falls, more than 7 million injuries, and 800,000 hospital admissions in the United States. The corresponding cost to Medicare alone exceeded $31 billion and $50 billion for all medical care (Centers for Disease Control and Prevention, 2017, August 17). Fall-related injuries belong to the 20 most costly medical conditions. Clinically, a large number of etiologies of falls have to be consid- ered. A useful initial approach is to determine whether a patient has suffered a drop attack or an accidental fall. In this discussion the term drop attack describes a sudden fall occurring without a prodrome that may or may not be associated with loss of consciousness and cannot be prevented by assistive devices. In contrast, falls reflect an inability to remain upright during a postural challenge. Potential etiologies drop attacks include cardiac, epileptic, vascular, sleep, and vestibular disorders, as well as congenital brain abnormalities and intracranial masses. In neurological practice, falling is most commonly associated with chronic disorders such as neuropathies, stroke, multiple sclerosis (MS), parkinsonism, and dementia. Affected patients have impaired control of stability and gait due to functional declines in neuromus- cular, sensory, vestibulocerebellar, and cognitive systems. Finally, the elderly, with their inevitable infirmities and accumulating functional deficits, frequently fall. These associations permit a classification of falls and drop attacks, as presented in Box 3.1. As is true for most neurological presentations, the medical history is essential in establishing the likely etiology of a patient’s fall. Aside from gender, age, medications, and neurological conditions, which all affect fall risk, answers to the following questions should be sought: @ @ @ D D D D 18 PART I Common Neurological Problems BOX 3.1 Causes and Types of Falls and Drops Drop Attacks With loss of consciousness: Syncope Seizures Without loss of consciousness: Transient ischemic attacks: Vertebrobasilar insufficiency Anterior cerebral artery ischemia Third ventricular and posterior fossa tumors Chiari malformation Otolithic crisis Cataplexy Falls Neuromuscular disorders (neuropathy, radiculopathy, and myopathy) Cerebral or cerebellar disorders Cryptogenic falls in the middle-aged Aging, neurodegeneration, and the neural substrate of gait and balance: Fear of falling Basal ganglia disorders: Parkinson disease Progressive supranuclear palsy and other parkinsonian syndromes The aged state aortic stenosis or right ventricular dysplasia, among others. A large atrial myxoma can present in the same manner. Cerebral hypoperfusion due to peripheral loss of vascular tone (orthostasis) is usually identifiable by a presyncopal syndrome of progressive lightheadedness, faintness, dimming of vision, and “rub- bery”-feeling legs, but even in the context of positive tilt-table test- ing, up to 37% of patients report a clinically misleading symptom of true, “cardiogenic” vertigo (Newman-Toker et al., 2008). Vertigo and downbeat nystagmus may also occur with asystole (Choi et al., 2010). Seizures Epileptic drop attacks are caused by several mechanisms, including asymmetrical tonic contractions of limb and axial muscles, loss of tone of postural muscles (atonic seizures), and seizure-related car- diac arrhythmias. Video-EEG monitoring of epileptic patients with a history of falls permits characterization of the various motor phe- nomena that cause loss of posture. Pediatric epileptic encephalopathy syndromes (e.g., Lennox-Gastaut syndrome and Dravet syndrome, as well as the myoclonic epilepsies) frequently present as drop attacks. A tilt-table test should be considered in children and adolescents to avoid overdiagnosing epilepsy (Sabri, Mahmodian, and Sadri, 2006). Epileptic drops in young patients with epileptic encephalopathy syn- dromes can be reduced with vagal nerve stimulation in some, as well as with clobazam, rufinamide (VanStraten and Ng, 2012) and cannabidiol oil (Thiele et al., 2018). Medically refractory cases may show improved control of epileptic drops, as well as developmental gains after cal- losotomy (Ueda, Sood, Asano, Kumar, and Luat, 2017). Falling as a consequence of the tonic axial component of startle-induced seizures may be controllable with lamotrigine. Paradoxically, some antiseizure drugs can precipitate epileptic drop attacks, such as carbamazepine in Rolandic epilepsy. In patients with a history of stroke, falling may be falsely attributed to motor weakness rather than to new-onset seizures. Destabilizing extensor spasms of spasticity can also be difficult to dis- tinguish from focal seizures. @ @ @ D D D as parasagittal meningiomas, posterior fossa and foramen magnum tumors, and subdural hematomas usually have baseline abnormalities of gait and strength. Falling may occur consequent to these impair- ments rather than to acute loss of muscle tone. Otolith Crisis During attacks of vertigo, patients often lose balance and fall. Approximately one in five patients with peripheral vestibular disorders experience drop attacks (Tomanovic and Bergenius, 2010). Meniere disease (see Chapter 22) may be complicated by “vestibular drop attacks”—Tumarkin otolithic crisis (Tumarkin, 1936)—in approxi- mately 6% of patients. Presumably, stimulation of otolith receptors in the saccule triggers inappropriate postural reflex adjustments via ves- tibulospinal pathways, resulting in falls without accompanying vertigo. Affected patients report feeling as if, without warning, they are being thrown to the ground. They may fall straight down or be propelled in any direction (Chen, Zhang, Zhang, and Tumarkin, 2020). One patient reported suddenly seeing and feeling her legs moving forward in front of her as she did a spontaneous backflip (personal communication Dr. R.B. Daroff). Vestibular drop attacks may also occur in elderly patients with unilateral vestibulopathies who do not satisfy diagnostic criteria for Meniere disease (H. Lee, Yi, Lee, Ahn, and Park, 2005). Cataplexy Cataplexy, the sudden loss of lower limb tone, is part of the tetrad of narcolepsy that also includes excessive daytime sleepiness, hypnagogic hallucinations, and sleep paralysis (see Chapter 101). Consciousness is preserved during a cataplectic attack, and the attack may vary in sever- ity from slight lower limb weakness to generalized and complete paralysis with abrupt falling. Once on the ground, the patient is unable to move but continues to breathe. The attacks usually last less than 1 minute, only rarely exceeding several minutes in duration. Cataplectic attacks are provoked by strong emotion and associated with laughter, Seizure Classification, 14 Absence Seizures, 14 Tonic-Clonic Seizures, 14 Complex Partial Seizures, 15 Investigations of Seizures, 15 Psychogenic Nonepileptic Spells, 15 Miscellaneous Causes of Altered Consciousness, 16 In patients with episodic impairment of consciousness, diagno- sis relies heavily on the clinical history described by the patient, and obtaining a detailed history from unaffected observers is often essential to clarifying the diagnosis. Laboratory investigations may also provide useful information. In a minority of patients, a cause for the loss of consciousness may not be established, and these patients may require longer periods of observation. Table 2.1 compares the clinical features of syncope and seizures. SYNCOPE The pathophysiological basis of syncope is the temporary failure of cerebral perfusion, with a reduction in cerebral oxygen availability. Syncope refers to a symptom complex characterized by lightheaded- ness, generalized muscle weakness, giddiness, visual blurring, tinnitus, and gastrointestinal (GI) symptoms. The patient may appear pale and feel cold and “sweaty.” The onset of loss of consciousness generally is gradual but may be rapid if related to certain conditions such as a car- diac arrhythmia or in the elderly. The gradual onset may allow patients to protect themselves from falling and injury. Factors precipitating a vasovagal syncopal episode (also known sometimes as a simple faint) include emotional stress, unpleasant visual stimuli, prolonged stand- ing, venipuncture, and pain. Although the duration of unconscious- ness is brief, it may range from seconds to minutes. During the faint, the patient may be motionless or display myoclonic jerks but never tonic-clonic movements. Urinary incontinence is uncommon. The pulse is weak and often slow because patients may be briefly bradycar- dic (from parasympathetic tone) and vasodilated. Breathing may be shallow and the blood pressure barely obtainable. As the fainting epi- sode corrects itself by the patient becoming horizontal, normal color returns, breathing becomes more regular, and the pulse and blood pressure return to normal. After the faint, the patient experiences some residual weakness, but unlike the postictal state, confusion, headaches, and drowsiness are uncommon. Nausea may be noted before the epi- sode and may still be present when the patient regains consciousness. The causes of syncope, which may often overlap, are classified by their pathophysiological mechanism (Box 2.1), but cerebral hypoperfusion is always the common final pathway. Rarely, vasovagal syncope may @ D1 F CD @ 2C @ C C@ @ ). @ 4 C F CHAPTER 2 Episodic Impairment of Consciousness 9 Syncope and Seizures Seizure No Diurnal or nocturnal pain, crowds, heat, exercise, fear, dehydration, Sleep deprivation, drug/alcohol withdrawal, venipuncture, prolonged standing illness, medication nonadherence Cyanosis or normal Rare longer, but can be very brief Brief Common Rhythmic jerks Common (with convulsive seizures) Common Common with convulsive seizures Common Common Occasional low blood pressure and heart rate during event; Rare exam may be completely normal after event is an underlying cardiac disorder slowing may occur during the event) Common History and Physical Examination The history and physical examination are the most important com- ponents 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 bas- ilar migraine is more common in young females. Although vasova- gal syncope can occur in older patients (Tan and Perry, 2008), when repeated syncope begins in later life, organic disease of the cerebral circulation or cardiovascular system usually is responsible and requires exhaustive investigation. A thorough history is the most important step in establishing the cause of syncope. The patient’s description usually establishes the diag- nosis. The neurologist should always obtain as full a description as pos- sible 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 symp- toms, 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. Be certain to ask about any prior events, and gather these same details for each event that the patient recalls. Cardiac syncope is defined as syncope caused by bradycardia, tachycardia, or hypotension due to low cardiac index, blood flow obstruction, vasodilation, or acute vascular dissection (Shen et al., diving, Valsalva 2017). Cardiac syncope should be suspected in patients with known cardiac disease. 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 arrhyth- mias but do not definitively establish that diagnosis as the cause for the syncope. In vasodepressor syncope and orthostatic hypotension, @ D1 F CD @ 2C @ C C@ @ ). @ 4 C F atheroma in the carotid artery wall. In contrast, an ectopic atrial or ven- tricular tachycardia will usually not be terminated by vagal maneuvers. It is recommended that all patients with syncope undergo a resting elec- trocardiogram as part of their initial evaluation (Shen et al., 2017). All patients with syncope should also undergo cardiac auscultation for the presence of cardiac murmurs and abnormalities of the heart sounds. Possible murmurs of concern include aortic stenosis, hyper- trophic cardiomyopathy with outflow tract obstruction, and mitral valve stenosis. An intermittent posture-related murmur may be asso- ciated with an atrial myxoma. A systolic click and late systolic murmur of mitral regurgitation in a young person suggests mitral valve pro- lapse. A pericardial rub suggests pericarditis. The finding of a murmur, rub, or abnormal click in a patient with syncope should prompt the physician to order an echocardiogram. All patients should undergo observation of the carotid and jugular venous pulses and auscultation of the neck. The degree of aortic steno- sis may be reflected at times in a delayed or weakened carotid upstroke. Carotid, ophthalmic, and supraclavicular bruits suggest underlying cerebrovascular disease. Jugular venous distention suggests conges- tive heart failure or other abnormal filling of the right heart, whereas a very low jugular venous pressure suggests hypovolemia. Carotid sinus massage should be avoided in patients with carotid bruits but may be useful in patients suspected of having carotid sinus syncope. It is important to keep in mind that up to 25% of asymptomatic persons may have some degree of carotid sinus hypersensitivity. Carotid mas- sage should be avoided in patients with suspected cerebrovascular dis- ease, even if they have no carotid bruit, and when performed should be under properly controlled conditions with electrocardiographic (ECG) and blood pressure monitoring. The response to carotid massage may be vasodepressor, cardioinhibitory, mixed, or minimal. Causes of Syncope Cardiac Arrhythmias Both bradyarrhythmias and tachyarrhythmias may result in syn- cope, and abnormalities of cardiac rhythm due to dysfunction from the sinoatrial (SA) node to the Purkinje network may be involved. Always consider arrhythmias in all cases in which an obvious alter- native mechanism is not established. Syncope due to cardiac arrhyth- mias generally occurs more quickly than syncope from other causes. Cardiac syncope may occur in any position, is occasionally exercise induced, and may occur in both congenital and acquired forms of heart disease. Although palpitations sometimes occur during arrhythmias, oth- ers are unaware of any cardiac symptoms. Syncopal episodes sec- ondary to cardiac arrhythmias may be more prolonged than benign syncope and often occur with less warning. Patients may injure themselves significantly during their fall. The most common arrhyth- mias causing syncope are AV block, SA block, and paroxysmal supra- ventricular and ventricular tachyarrhythmias. AV block describes disturbances of conduction occurring in the AV conducting system, which include the AV node to the bundle of His and the Purkinje network. SA block describes a failure of consistent pacemaker func- tion of the SA node. Paroxysmal tachycardia refers to a rapid heart rate that comes on intermittently. It may be secondary to an ectopic focus or reentrant loop outside the SA node but above the ventricle (supraventricular), or it may be from a source below the AV node (ventricular). In patients with implanted pacemakers, syncope can occur because of pacemaker malfunction. Atrioventricular Block AV block is probably the most common cause of arrhythmic car- diac syncope. The term Stokes-Adams attack describes disturbances @ D1 F CD @ 2C @ C C@ @ ). @ 4 C F CHAPTER 2 Episodic Impairment of Consciousness 11 Reflex Cardiac Arrhythmias A hypersensitive carotid sinus may be a cause of syncope in the elderly, most frequently men. Syncope may result from a reflex sinus brady- cardia, sinus arrest, or AV block; peripheral vasodilatation with a fall in arterial pressure; or a combination of both. Although 10% of the population older than 60 years of age may have a hypersensitive carotid sinus, not all such patients experience syncope. Accordingly, consider this diagnosis only when the clinical history is compatible. Carotid sinus syncope may be initiated by wearing a tight collar, by rapidly turning the head (including when patients do so on their own), or by carotid sinus massage on clinical examination. When syncope occurs, the patient usually is upright, and the duration of the loss of conscious- ness generally is a few minutes. On regaining consciousness, the patient is mentally clear. Unfortunately, no accepted diagnostic criteria exist for carotid sinus syncope, and the condition is likely overdiagnosed. Syncope in certain patients can be induced by unilateral carotid massage or compression; however, in those with atherosclerotic carotid disease, this can sometimes cause partial or complete occlusion of the ipsilateral carotid artery or release of atheromatous emboli and subse- quent stroke. Because of these risks, carotid artery massage is contrain- dicated in those with known or suspected carotid atherosclerotic disease. The rare syndrome of glossopharyngeal neuralgia is characterized by intense paroxysmal pain in the throat and neck accompanied by bradycardia or asystole, severe hypotension, and, if prolonged, sei- zures. Episodes of pain may be initiated by swallowing but also by chewing, speaking, laughing, coughing, shouting, sneezing, yawning, or talking. The episodes of pain always precede the loss of conscious- ness (see Chapter 20). Rarely, cardiac syncope may be due to bradyar- rhythmias consequent to vagus nerve irritation caused by esophageal diverticula, tumors, or aneurysms in the region of the carotid sinus or by mediastinal masses or gallbladder disease. Decreased Cardiac Output Syncope may occur as a result of a sudden and marked decrease in cardiac output. Causes are both congenital and acquired. Tetralogy of Fallot, the most common congenital malformation causing syncope, does so by producing hypoxia due to right-to-left shunting. Other con- genital conditions associated with cyanotic heart disease also may cause syncope. Ischemic heart disease and myocardial infarction (MI), aortic stenosis, hypertrophic cardiomyopathy with outflow tract obstruc- tion, pulmonary hypertension, pulmonic valve stenosis, acute massive pulmonary embolism, atrial myxoma, and cardiac tamponade may sufficiently impair cardiac output to cause syncope. Exercise-induced or effort syncope may occur in aortic or subaortic stenosis and other states in which there is limited cardiac output and associated periph- eral vasodilatation induced by the exercise. Exercise-induced cardiac syncope and exercise-induced cardiac arrhythmias may be related. In patients with valvular heart disease, the cause of syncope may be related to flow through the valve or to arrhythmias. Syncope in valvular disease may also be due to reduced cardiac output secondary to myocar- dial failure, to mechanical prosthetic valve malfunction, or to thrombus formation at a valve. Mitral valve prolapse generally is a benign condi- tion, but, rarely, cardiac arrhythmias can occur. The most significant arrhythmias are ventricular. In atrial myxoma or with massive pulmo- nary embolism, a sudden drop in left ventricular output may occur. In atrial myxoma, syncope frequently is positional and occurs when the tumor falls into the AV valve opening during a change in position of the patient, thereby causing obstruction of the ventricular inflow. Decreased cardiac output also may be secondary to conditions caus- ing an inflow obstruction or reduced venous return. Such conditions include superior and inferior vena cava obstruction, tension pneumo- thorax, constrictive cardiomyopathies, constrictive pericarditis, and @ D1 F CD @ 2C @ C C@ @ ). @ 4 C F pathways, producing orthostatic hypotension. Accordingly, conditions that affect both the central and peripheral baroreceptor mechanisms may cause orthostatic hypotension (Benafroch, 2008). Cerebrovascular Ischemia Syncope occasionally may result from reduction of cerebral blood flow in either the carotid or vertebrobasilar system in patients with extensive occlusive disease. Most frequently, the underlying condition is athero- sclerosis of the cerebral vessels, but reduction of cerebral blood flow due to cerebral embolism, mechanical factors in the neck (e.g., severe osteo- arthritis), and arteritis (e.g., Takayasu disease or cranial arteritis) may be responsible. In the subclavian steal syndrome, a very rare impairment of consciousness is associated with upper extremity exercise and resultant diversion of cerebral blood flow to the peripheral circulation. In elderly patients with cervical skeletal deformities, certain head movements such as hyperextension or lateral rotation can result in syncope secondary to vertebrobasilar arterial ischemia. In these patients, associated vestibular symptoms are common. Occasionally, cerebral vasospasm secondary to basilar artery migraine or subarachnoid hemorrhage may be respon- sible. Insufficiency of the cerebral circulation frequently causes other neurological symptoms, depending on the circulation involved. Reduction in blood flow in the carotid circulation may lead to loss of consciousness, lightheadedness, giddiness, and a sensation of an impending faint. Reduction in blood flow in the vertebrobasilar system also may lead to loss of consciousness, but dizziness, lightheadedness, drop attacks without loss of consciousness, and bilateral motor and sensory symptoms are more common. However, dizziness and light- headedness alone are not symptoms of vertebrobasilar insufficiency. Syncope due to compression of the vertebral artery during certain head and neck movements may be associated with episodes of vertigo, dis- equilibrium, or drop attacks. Patients may describe blackouts on look- ing upward suddenly or on turning the head quickly to one side. In general, symptoms persist for several seconds after the movement stops. In Takayasu disease, major occlusion of blood flow in the carotid and vertebrobasilar systems may occur; in addition to fainting, other neurological manifestations are frequent. Pulsations in the neck and arm vessels usually are absent, and blood pressure in the arms is unob- tainable. The syncopal episodes characteristically occur with mild or moderate exercise and with certain head movements. Cerebral vaso- spasm may result in syncope, particularly if the posterior circulation is involved. In basilar artery migraine, usually seen in young women and children, a variety of brainstem symptoms also may be experienced, and it is associated with a pulsating headache. The loss of consciousness usu- ally is gradual, but a confusional state may last for hours. Metabolic Disorders A number of metabolic disturbances, including hypoglycemia, anoxia, and hyperventilation-induced alkalosis, may predispose affected persons to syncope, but usually only lightheadedness and dizziness are experi- enced. The abruptness of onset of loss of consciousness depends on the acuteness and reversibility of the metabolic disturbances. Syncope due to hypoglycemia usually develops gradually. The patient has a sensation of hunger; there may be a relationship to fasting, a history of diabetes melli- tus, and a prompt response to ingestion of food. Symptoms are unrelated to posture but may increase with exercise. During the syncopal attack, no significant change in blood pressure or pulse occurs. Hypoadrenalism may give rise to syncope by causing orthostatic hypotension. Disturbances of calcium, magnesium, and potassium metabolism are other rare causes of syncope. Anoxia may produce syncope because of the lack of oxygen or through the production of a vasodepressor type of syncope. A feeling of lightheadedness is common, but true syncope is less common. Patients with underlying cardiac or pulmonary disease are susceptible. In patients @ D1 F CD @ 2C @ C C@ @ ). @ 4 C F CHAPTER 2 Episodic Impairment of Consciousness 13 rhythm or conduction or suggest 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 investi- gations that may be helpful include echocardiography, exercise stress testing, radionuclide cardiac scanning, prolonged Holter monitoring for the detection of cardiac arrhythmias, and cardiac magnetic reso- nance imaging (MRI). 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, typically up to 30 days. Implantable loop recorders can pro- vide long-term rhythm monitoring in patients suspected of having a seldom but highly symptomatic 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 to localize the site of conduction disturbances. Exercise testing should be considered in anyone with a history of exertional symptoms. Consider tilt-table testing in patients with unexplained syncope in high-risk set- tings or with recurrent faints in the absence of heart disease (Kapoor, 1999). Falsepositives occur, and 10% of healthy persons may faint during the test. Tilt testing frequently uses pharmacological agents such as nitroglycerin or isoproterenol, which increase sensitivity but decrease specificity. The specificity of tilt-table testing is approxi- mately 90%, but the sensitivity differs in different patient populations. In patients suspected to have syncope due to cerebrovascular causes, noninvasive diagnostic studies including Doppler flow studies of the cerebral vessels and MRI or magnetic resonance angiography may pro- vide useful information. The American Academy of Neurology recom- mends that carotid imaging not be performed unless there are other focal neurological symptoms (Langer-Gould et al., 2013). Cerebral angiography is sometimes useful. Electroencephalography (EEG) is useful in differentiating syncope from epileptic seizure disorders. EEG should be obtained only when a seizure disorder is suspected and gen- erally 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 vasode- pressor) 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 to identify patients who need urgent referral. The presence of cardiac failure, anemia, abnormal ECG, or systolic hypotension helps to identify these patients (Parry and Tan, 2010). A systematic review of the SFSR accuracy (Saccilotto et al., 2011) found that the rule cannot be applied safely to all patients and should only be applied to patients for whom no cause of syncope is identified. The rule should be used only in conjunction with clinical evaluation, particularly in elderly patients. The Risk Stratification of Syncope in the Emergency Department (ROSE) study is another risk stratification evaluation of patients who present to the emergency department (Reed et al., 2010). Independent predictors of 1-month serious outcome were elevated brain natriuretic peptide concentration, positive fecal occult blood, hemoglobin of 90 g/L or less, oxygen saturation of 94% or less, and Q wave on the ECG. Although these risk scores can be used, there has been limited exter- nal validation, and there is no evidence to support that their use leads to better clinical outcomes than with unstructured clinical judgment (Shen et al., 2017). @ D1 F CD @ 2C @ C C@ @ ). @ 4 C F of incomplete development of the nervous system; specifically, the lack of CNS myelination in infants leads to more migratory jerking rather than the synchronous jerking seen with tonic-clonic seizures in children and adults. The neurological examination may reveal an underlying structural disturbance responsible for the seizure disorder. Perinatal 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 charac- teristic of some of the neurodegenerative disorders. If examination occurs immediately after a suspected tonic-clonic seizure, the neurologist should search for abnormal signs such as focal motor weakness (“Todd paralysis”) and reflex asymmetry and for pathological reflexes such as a Babinski sign. Such findings may help to confirm that the attack was a seizure and suggest a possible lateraliza- tion or location of the seizure focus. le SEIZURE CLASSIFICATION Seizure classification is based on their functional distribution and on the structural neuroanatomy of the brain (see Chapter 100). The location and extent of a seizure’s involvement is reflected in its clinical manifestation, termed its semiology. that involve 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%–40% of patients. The absence seizure is a well-defined clinical and electrographic 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 abrupt interruption of activity, or behav- ioral arrest. 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 (repetitive purposeless movements), most often fluttering of the eyelids. 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 10–15 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 mus- culature or extremities, minor face or extremity automatisms, or auto- nomic phenomena such as pallor, flushing, tachycardia, piloerection, mydriasis, or urinary incontinence. If absence seizures are suspected, office diagnosis is frequently pos- sible by having the patient hyperventilate for 3–4 minutes, which often, although not always, induces an absence seizure. Tonic-Clonic Seizures The tonic-clonic seizure is the most dramatic manifestation of epilepsy and is characterized by motor activity and loss of consciousness. Tonic- clonic seizures may be the only manifestation of epilepsy or may be asso- ciated 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 con- traction lasting 10–20 seconds. Following this phase is a clonic phase @ D1 F CD @ 2C @ C C@ @ ). @ 4 C F CHAPTER 2 Episodic Impairment of Consciousness 15 TABLE 2.2 Comparison of Absence and Complex Partial Seizures Complex Partial Feature Absence Seizure Seizure Neurological status Normal May have positive his- tory or examination Age at onset Childhood or adolescence Any age Aura or warning No Common Onset Abrupt Gradual Duration Seconds Typically 1–2 minutes Automatisms Simple More complex Provocation by hyper- Common Uncommon ventilation Termination Abrupt Gradual Postictal phase No Confusion, fatigue Frequency Possibly multiple seizures Occasional per day Electroencephalogram 3 Hz generalized spike- Focal epileptic and-wave discharges or focal slowing Neuroimaging Usually normal findings May demonstrate focal lesions in the diagnosis of absence seizures. EEG supplemented with simulta- neous video monitoring may document events of loss or alteration of consciousness, allowing for a strict correlation between EEG changes and the clinical manifestations in question. Video EEG is also is useful in distinguishing epileptic seizures from nonepileptic phenomena. In most patients, an accurate diagnosis requires only a carefully taken clinical history, physical examination, and the aforementioned investigations. Others present a diagnostic dilemma and may require more extensive and invasive testing. Psychogenic Nonepileptic Spells Nonepileptic spells are paroxysmal episodes of altered behavior that superficially resemble epileptic seizures but lack the expected EEG epi- leptic changes (Ettinger et al., 1999). However, 10%–20% of patients with nonepileptic spells also experience epileptic seizures and vice versa. In such cases, carefully determining semiological differences among the spell types is important when the spells are ongoing despite seemingly appropriate interventions. 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 spells. Most frequently, they superficially resemble tonic-clonic seizures, with whole-body shaking and unresponsiveness. They generally are abrupt in onset, typically 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 spells tend to be more prolonged than tonic-clonic seizures. Pelvic thrusting and back arching are common. Eye closure is common in nonepileptic spells, whereas the eyes tend to be open in epileptic seizures (Chung et al., 2006). During and immediately after the spell, the patient may not respond to verbal or painful stimuli. Cyanosis does not occur, and focal neurological signs and pathological reflexes are absent. PNES syncope without prominent motor activity can resemble. These spells are not uncommon and are often referred to as psycho- genic pseudosyncope (Tannemaat et al., 2013). The apparent loss of consciousness in these patients may be longer than in syncope. The @ D1 F CD @ 2C @ C C@ @ ). @ 4 C F TABLE 2.3 Comparison of Psychogenic and Epileptic Seizures of nonepi- Attack Psychogenic Epileptic Feature Seizure Seizure Stereotypy of attack Often variable Stereotypical Onset or progression Gradual More rapid Duration May be prolonged Typically 1–2 minutes Diurnal variation Daytime Nocturnal or daytime Injury Rare Can occur with tonic-clonic seizures Tongue biting Rare (typically tip of Can occur with tonic-clonic tongue) seizures (lateral tongue or inside of cheek) Ictal eye closure Common Rare (eyes typically open) Urinary incontinence Rare Frequent Vocalization May occur; variable Tonic-clonic seizures may (often crying, moaning) have ictal cry at onset Motor activity Prolonged, uncoordi- Typically unilateral rhyth- nated; pelvic thrusting, mic jerking, dystonic back arching posturing of a limb, or synchronous tonic-clonic activity Prolonged loss of Common Rare muscle tone Postictal confusion Rare Common (several minutes, often fatigued for hours desiring sleep) Postictal headache Rare Common Postictal crying Common Rare Relation to medica- Unrelated Usually related tion changes Relation to menses Uncommon Occasionally increased in women Triggers Emotional disturbances Sleep deprivation, illness, medication nonadher- ence Frequency of attacks More frequent, up to Less frequent daily Interictal EEG Normal Frequently abnormal findings Reproduction of Sometimes No attack by sugges- tion Ictal EEG findings Normal Abnormal Presence of second- Common Uncommon ary gain Presence of others Frequently Variable Psychiatric distur- Very common (though not Variable bances always apparent) EEG, Electroencephalogram. Breath-holding spells do not require treatment, but when interven- tion is required, levetiracetam (Keppra) is effective for prophylaxis at ordinary anticonvulsant doses. Several pediatric metabolic disorders may have clinical manifestations of alterations of consciousness, lethargy, or seizures (see Chapter 90). The complete reference list is available online at https://expertconsult. inkling.com/. @ D1 F CD @ 2C @ C C@ @ ). @ 4 C F 3 Falls and Drop Attacks Bernd F. Remler, Hatim Attar Falls, 19 Neuromuscular Disorders and Myelopathy, 19 Other Cerebral or Cerebellar Disorders, 19 Cryptogenic Falls in the Middle-Aged, 19 Aging, Neurodegeneration, and the Neural Substrate of Gait and Balance, 20 What were the circumstances of the fall and has the patient fallen before? Did the patient lose consciousness? If so, for how long? Did lightheadedness, vertiginous sensations, or palpitations precede the event? Is there a history of a seizure disorder, startle sensitivity, excessive day- time sleepiness, or falls precipitated by strong emotions? Does the patient have headaches or migraine attacks associated with weakness? Does the patient have vascular risk factors, and were there previous symptoms suggestive of transient ischemic attacks (TIAs)? Are there symptoms of sensory loss, limb weakness, or stiffness? Is there a history of visual impairment, hearing loss, vertigo, or tinni- tus? The neurological examination identifies predisposing functional deficits. However, in the case of drop attacks, the examination is often normal, posing a diagnostic challenge. In such patients, neuroimaging is necessary. Further workup is tailored to the clinical circumstance and may include vascular imaging, cardiac and autonomic studies, electroencephalogram (EEG), nocturnal polysomnography, and, rarely, genetic and metabolic testing when related conditions are sus- pected. Psychogenic disorders of station and gait need to be considered in patients who frequently experience near falls without injuries. of DROP ATTACKS WITH LOSS OF CONSCIOUSNESS Syncope The manifestations and causes of syncope are described in Chapter 2. Severe ventricular arrhythmias and hypotension lead to cephalic ischemia and falling. With sudden-onset third-degree heart block (Stokes-Adams attack), the patient loses consciousness and falls with- out warning. Other causes of decreased cardiac output, such as brady- arrythmias or tachyarrhythmias, are believed to be associated with prodromal faintness. However, reliance on history to determine a car- diac etiology of a fall may be inadequate because elderly patients with sick sinus syndrome can be amnestic for presyncopal symptoms. When occurring in young athletes, exertional drop attacks indicate the pres- ence of potentially life-threatening structural heart disease, including 17 @ D1 F CD @ 2C @ C C@ @ ). @ 4 C F DROP ATTACKS WITHOUT LOSS OF CONSCIOUSNESS Transient Ischemic Attacks Drop attacks secondary to TIAs are sudden falls occurring without warning or obvious explanation such as tripping. Loss of consciousness either does not occur or is only momentary; the sensorium and lower limb strength are intact immediately or shortly after the patient hits the ground. Between episodes the neurological examination should not reveal lower limb motor or sensory dysfunction. The vascular dis- tributions for drop attacks from TIAs are the posterior circulation and the anterior cerebral arteries. Vertebrobasilar Insufficiency Drop attacks caused by posterior circulation insufficiency result from transient ischemia to the corticospinal tracts or the paramedian reticu- lar formation. They are rarely an isolated manifestation of vertebrobas- ilar insufficiency, because most patients have a history of TIAs that include the more common signs and symptoms of vertigo, diplopia, ataxia, weakness, and hemisensory loss. Occasionally, however, a drop attack is the ominous precursor of severe neurological deficits due to progressive thrombosis of the basilar artery and may precede perma- nent ischemic damage only by hours. Aside from embolism and focal stenosis in the posterior circulation, vertebrobasilar insufficiency can also be caused by the subclavian steal syndrome (Osiro S 2012). Anterior Cerebral Artery Ischemia Anterior cerebral artery (ACA) ischemia causes drop attacks by impairing perfusion of the parasagittal premotor and motor cortex controlling the lower extremities. Origination of both ACAs from the same root occurs in approximately 20% of the population and predis- poses to ischemic drop attacks from a single embolus. Paraparesis and even tetraparesis can result from simultaneous infarctions in bilateral anterior cerebral artery (ACA) territories (Kang and Kim, 2008). Limb- shaking TIAs can be associated with drop attacks and occur in the con- text of the same vascular variant described earlier (Gerstner, Liberato, and Wright, 2005). Rare cases of drop attacks arising in the context of carotid dissection (Casana et al., 2011) and frontal arteriovenous (AV) fistulas (Oh, Yoon, Kim, and Shim, 2011) have been described. Third Ventricular and Posterior Fossa Abnormalities Drop attacks can be a manifestation of colloid cysts of the third ventri- cle, Chiari malformation (“Chiari drop attack”), or mass lesions within the posterior fossa. With colloid cysts, unprovoked falling is the sec- ond most common symptom, after position-induced headaches. This history may be the only clinical clue to the diagnosis because the neu- rological examination can be entirely normal. Pineal cysts are also an occasional cause of drop attacks by producing a sudden rise in cerebro- spinal fluid (CSF) pressure with position-dependent obstruction (“ball valve effect”) of the ventricular system (Fernandez-Miranda, 2018). Drop attacks occur in 2%–3% of patients with Chiari malformation and can be associated with loss of consciousness. They often resolve after decompression surgery (Straus, Foster, Zimmerman, and Frim, 2009). Posterior fossa arachnoid cysts are common but only occa- sionally associated with tonsillar ectopia. This combination of anom- alies has also been reported to cause drop attacks (Killeen, Tromop, Alexander, and Wickremesekera, 2013). Drops induced by rapid head turning were considered pathognomonic of cysticercosis of the fourth ventricle in the early twentieth century (Brun sign). The contempo- rary maneuver of cervical spine manipulation is rarely associated with a drop attack (Sweeney and Doody, 2010). Patients who experience sudden drop attacks in the context of intracranial mass lesions such D @ D1 F CD @ 2C @ C C@ @ ). @ 4 C F CHAPTER 3 Falls and Drop Attacks 19 sensory tracts traverse the cord. This is particularly true for multiple sclerosis patients with gait and balance dysfunction, of whom at least half fall once or more a year (Cameron and Nilsagard, 2018). Multiple sclerosis patients older than 55 years have a high rate of injurious falls (Peterson, Cho, von Koch, and Finlayson, 2008), and FOF is com- mon in this group (Kalron and Achiron, 2014). However, even elderly multiple sclerosis patients can attain marked reductions in fall risk with home-based balance and strength training (Sosnoff, Finlayson, McAuley, Morrison, and Motl, 2014). Stroke Strokes present with any combination of neurological deficits that pre- dispose to falls in the acute and chronic state: weakness, ataxia, sensory deafferentation, hemianopsia, diplopia, anosognosia, hemineglect, vestibular tilting, and acquired gait abnormalities (Chen, Novak, and Manor, 2014) are obvious risk enhancing factors. Poststroke depres- sion and immobilization further aggravate this risk, which is at least twice as high in stroke patients compared with age-matched con- trols. The majority of falls occur within the home environment and come with a high risk (>70%) of injuries (Schmid et al., 2013). The poststroke risk of a hip fracture is doubled and is particularly high in women within 3 months of the ischemic event (Pouwels et al., 2009). Concerns for such injuries have increased prevention efforts but have also provoked restrictions on patient mobility in acute care and reha- bilitation facilities (Inouye, Brown, and Tinetti, 2009), because falls typically occur when patients attempt to get out of bed, stand up, or walk. Fortunately, concerted efforts have yielded significant reductions of fall and injury incidence in such institutions (Services, 2014, May 7). flaccid Other Cerebral or Cerebellar Disorders Metabolic encephalopathies may cause a characteristic transient loss of postural tone (asterixis). If this is extensive and involves the axial mus- culature, episodic loss of the upr

Episodic Impairment of Consciousness PDF

Document Details

Tags

Related

Summary

Full Transcript

Upgrade to continue