Neurolog Volume 10, Number 4

December 1990

0m.n Devinsky, M.D.

The epilepsies are a group of heterogeneous disorders characterized by spontaneous, recurrent, paroxysmal episodes of altered behavior due to excessive neuronal activity. The fundamental symptom in epilepsy is the seizure, which may assume a diverse spectrum of clinical features, including hallucinations and illusions in all sensory modalities, psychic phenomena such as deja -vu, affective and autonomic symptoms, impairment of consciousness, and involuntary movements. Epilepsy is common; 9% of the United States population will have at least one epileptic seizure during their lifetime and more than 1% have epilepsy. Correct, prompt seizure diagnosis is essential because most patients are well controlled with one drug or by eliminating precipitating factors, such as alcohol. Failure to recognize and treat seizures can lead to accidental death from impaired consciousness while driving, missed therapeutic opportunities (early surgery for tumors), education and employment handicaps, and psychosocial devastation. Alternatively, incorrectly diagnosing epilepsy can cause permanent loss of self-esteem, employment, and driving privileges. Therefore, patients with suspected epilepsy must be carefully evaluated and epilepsy must be diagnosed conservatively.

EVALUATION Seizures are diagnosed primarily by history. A complete description by the patient and observer as to what was experienced and witnessed is the cornerstone of diagnosis. In the outpatient setting, it may be helpful to contact the patient prior to the initial evaluation and ask for observations made by witnesses during the attack. If possible, the observer should accompany the patient for the office visit.' The goal of the history is to obtain a precise description of the episode. If the initial history is vague, ask the patient and witness to observe carefully and immediately record their findings after future episodes. Instruct the observer to test the patient's responsiveness (for example, "Show me your left thumb") and memory (for example, "Remember the color yellow") if there is uncertainty about the integrity of these functions during the episode. The command to show a body part assesses responsiveness without requiring verbal output and will distinguish confusion from anterior (Broca's) aphasia. T h e memory test is helpful because many patients adamantly, but incorrectly, deny impairment of consciousness or memory.

Associate Professor of Neurology, New York University School o f Medicine, a n d the Hospital for Joint Diseases, New York, New York Reprint requests: Dr. Devinsky, Hospital for Joint Diseases, 301 East 17th Street, New York, NY 10003 Copyright O 1990 by Thieme Medical Publishers, Inc., 381 Park Avenue South, New York, NY 10016. All rights reserved.

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The Differential Diagnosis of Epilepsy

Physical examination provides important etiologic clues. Blood pressure and heart rate in supine and upright positions, neurocutaneous lesions, murmurs, and bruits are important. Complete neurologic examination is essential. Hyperventilation may reproduce typical episodes; a high index of suspicion is required because paroxysmal behavioral problems presenting to neurologists are often due to hyperventilati~n.~ Laboratory studies are directed at specific diagnostic considerations. Blood chemistries and cell counts are routinely performed but rarely helpful. If a metabolic or toxic cause is suspected, blood and urine studies at or near the time of the episode provide the highest yield. Cardiovascular disorders are evaluated with electrocardiography (ECG), 24hour ambulatory ECG, carotid sinus or ocular compression under ECG monitoring, and echocardiography. Cardiac tests are important in the pediatric as well as the adult p o p u l a t i ~ n . ~ , ~ A normal electroencephalogram (EEG) does not exclude epilepsy and epileptiform discharges do not prove that episodes are epileptic. Epileptiform discharges occur in approximately 2% of the normal population and u p to 10% of children with Age influences epileptogenicity of paroxysmal EEG findings; occipital spikes between ages 3 and 5 years and central-midtemporal spikes between ages 3 and 12 years are associated with seizures in less than 70% of patientss Prolonged EEG recordings that include sleep are more likely to demonstrate epileptiform discharges. T h e most helpful EEG is one during which an episode is recorded. Video-EEG monitoring of episodes is particularly helpful in making or excluding the diagnosis of epilepsy, since behavior and EEG can be correlated. Additional testing, including polysomnography, computed tomography, magnetic resonance imaging, and psychologic or psychiatric evaluation, is often needed.



Differentiation of syncope from seizure is a common problem; both are frequent and occur in all age groups. Syncope is a transient loss of consciousness from acute decrease in cerebral blood flow.g The diagnosis of syncope is supported if episodes (1) exclusively occur while standing or sitting, (2) are precipitated by anxiety or pain, (3) are associated with facial pallor and sweating, and (4) are not associated with tonic-clonic movements and tongue biting or postepisode confusion, lethargy,


and headache. Decreased heart rate at onset suggests syncope, although partial seizures do, rarely, cause bradycardia.I0 Prodromal symptoms such as epigastric sensation, fear, flushing, dizziness, and feelings of unreality occur with both syncope and seizures. Symptoms such as olfactory hallucination or deja vu are more specific for partial seizures. Slight stiffening or clonic jerking may occur in syncope; with prolonged anoxia, generalized tonicclonic seizures (convulsive syncope) occur. While history is usually sufficient to distinguish syncope and seizures, routine as well as ambulatory 24-hour ECG and EEG studies may be required for diagnosis. There are many cardiovascular causes of syncope. Vasovagal syncope is the most common cause and is usually accompanied by decreased vasomotor tone and heart rate." Fear, pain (for example, venipuncture), and prolonged upright posture in a hot environment are frequent precipitants. Carotid sinus syncope is uncommon. Attacks occur in patients with atheroma or other lesions near the carotid bifurcation and are precipitated by wearing tight collars or by head-turning.I2 Diagnosis should be confirmed by unilateral carotid massage with ECG and blood pressure monitoring. Carotid sinus hypersensitivity (greater than 50% reduction in sinus rate, or systolic pressure decrease of 40 mmHg) suggests, but is not diagnostic of, carotid sinus syncope. Glossopharyngeal reflex syncope is rare and results from irritation of the ninth cranial nerve, usually by head and neck ~ancer.'".'~ Respiratory syncope is caused by increased intrathoracic pressure impairing venous return to the heart. Cough syncope is the most common form and typically occurs with asthma, emphysema, and chronic bronchi ti^.'^,"' When cough syncope produces marked cerebral hypoxia, it may cause convulsive movements and amnesia. In these cases, differentiation from epilepsy can be difficult, since the patient may not recall violent cough prior to impaired consciousness. Direct observation or video-EEG monitoring may establish the diagnosis. Wind or brass instrument players and singers occasionally faint as the result of prolonged expiration. Rare cases of defecation syncope result from raised intrathoracic pressure. Respiratory syncope also affects weight lifters who hyperventilate and then raise their intra-abdominal and intrathoracic pressures. Decreased cardiac output causes syncope as a result of decreased filling of the left ventricle, arrhythmias, and obstruction to left ventricular outflow. These and other disorders causing syncope are beyond the scope of this discussion but have Micturition syncope been extensively re~iewed.~." characteristically occurs in men who arise from

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sleep and faint toward the end of, or just after, ur- but partial seizures should be ~onsidered.'~ Also, ination. T h e principal mechanism is removal of the rhythmic involuntary movements mimicking clonic bladder-pressor stimulus with a contribution of seizures can occur in nonepileptic ischemic atsleep-induced vasodilation.18Arrhythmias account tacks." The movements are precipitated by sitting for 20% of syncopal episodes. Arrhythmias and or standing and relieved by lying down. Patients structural cardiovascular disorders (for example, have occlusion or high-grade stenosis of the interaortic stenosis and myocardial infarction) are as- nal or common carotid artery on the side opposite sociated with a 30% 1-year mortality rate.Ig Am- the affected extremities. bulatory ECG monitoring is essential for diagnosis MIGRAINE and should be performed in patients with syncope of unknown cause. Migraine is a hereditary disorder manifested Breath-holding spells, which may cause loss of by predominantly unilateral throbbing headaches consciousness and posture, occur in almost 5% of usually beginning before age 35 years. Classic mi~ h i l d r e n .These ~ nonepileptic episodes are most graine occurs in l%, and common migraine in u p common between ages 6 and 18 months and cease to lo%, of the population. Classic migraine and the spontaneously before age 6 years. A family history less frequent migraine variants (acute confusional of similar episodes is present in 25% of cases. and basilar migraine) may be misdiagnosed as epiBreath-holding spells are divided into cyanotic lepsy because both are episodic, paroxysmal dis(75%) and pallid (25%), although 15% of children orders with overlapping neurologic symptoms. have both types. Cyanotic spells occur after pro- Migraine equivalents, neurologic or visceral symplonged crying; and, if impairment of conscious- toms without headache, are also misdiagnosed as ness is sustained, clonic jerks may occur. Ocular partial seizures; abdominal pain in children is the compression produces bradycardia or brief asys- most common migraine equi~alent.~' Epileptiform tole. Pallid breath-holding spells follow fright or discharges are increased among migraineursZ8and injury; an element of surprise is often present. have been reported in u p to 10% of children with Crying is usually brief and clonic jerks are common migraine.2gUnilateral throbbing headache associat the end of the episode. Ocular compression in- ated with nausea and vomiting strongly suggests duces asystole lasting at least 2 seconds in most pa- migraine, especially when supported by positive tients. Because asystole may be prolonged after family history. such maneuvers, resuscitative facilities should be T h e aura in classic migraine is usually visual, available. but olfactory hallucination^,^^ deja vu, and other Breath-holding spells are commonly misdia- symptoms may occur.31These are incorrectly congnosed as seizures, especially when convulsive sidered specific for partial seizures. Acute confumovements occur. However, there is no association sional migraine occurs in u p to 5% of children who between breath-holding spells and epilepsy. Anti- have migraine3' and presents with clouding of conepileptic drugs have no effect on these episodes. sciousness. Agitation, aphasia, nausea, and vomitThe mainstay of therapy is reassurance, although ing may be a ~ s o c i a t e d .T~h~e headache occurs at occasional children with frequent pallid breath- onset or after confusion has resolved. Episodes last holding spells benefit from atropine. Approxi- 20 minutes to 12 hours. EEG during the attack typmately 20% of breath-holders have syncopal epi- ically demonstrates dominant hemisphere slowing. sodes in adolescence or adulthood. Differential diagnosis includes nonconvulsive staMitral valve prolapse occurs in 5% of adults, tus epilepticus, encephalitis, drug intoxication, and predominantly women. Although most individuals metabolic disorders. Basilar migraine consists of are asymptomatic, chest pain, dizziness, arrhyth- episodic headache with signs and symptoms refermias, dysautonomia, syncope, vascular headache, able to the brainstem and cerebellum, including transient ischemic attacks, and panic attacks occur vertigo, tinnitus, nausea, vomiting, ataxia, facial Z 4 and may be confused with partial ~eizures.~' pain and numbness, visual loss, unilateral or bilateral weakness and sensory changes, and loss of consciousness." Adolescent girls are most often afCEREBROVASCULAR DISORDERS fected and the attacks respond to antimigraine or Transient ischemic attacks cause brief, epi- antiepileptic drugs.35 in some patients, basilar misodic neurologic dysfunction and are usually easily graine and seizures coexist.36 distinguished from seizures. However, certain negative symptoms such as speech arrest occur during MOVEMENT DISORDERS both ischemic and epileptic . . attacks. Recurrent cerebral ischemia after stroke is the usual cause of Tics are sudden, stereotyped, irresistible moveparoxysmal speech arrest, aphasia, or paresthesia, ments or utterances that are exacerbated by stress

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Spasmus nutans is characterized by the triad of head nodding, nystagmus, and torticollis. Onset is between 2 weeks and 3 years; symptoms usually remit within 3 years. Nystagmus is the most constant and persistent feature. T h e distinctive fine nystagmus tends to (1) be asymmetric in the two eyes, (2) vary with gaze, and (3) simulate a quiver. This benign, idiopathic disorder requires no treatment, and should not be confused with epilepsy. SLEEP DISORDERS

Irresistible sleep attacks and excessive daytime sleepiness are the essential components of narcolepsy. The disorder typically begins before age 25 years and persists throughout life. Sleep attacks vary from seconds to half an hour and occur most often during relaxing activities (including driv'These spells can be misdiagnosed as atonic, absence, or complex partial seizures. Cataplexybrief (less than 1 minute) episodes of decreased muscle tone causing falls, jaw or head drooping, or knee buckling--occurs in 75% of narcoleptics. Cataplexy is usually triggered by strong emotion such as laughter or anger. Attacks are confused with atonic seizures. T h e other associated symptoms of narcolepsy, sleep paralysis and hypnagogic hallucinations, occur during the transition from wakefulness to sleep and are present in approximately a third of patients. Spells of automatic behavior and amnesia, lasting seconds to more than an hour, are experienced by 50% of narcoleptics4" and are misdiagnosed as complex partial seizures. History, polysomnography, and multiple sleep latency test with rapid eye movement (REM) sleep onset are used to make the diagnosis. Night terrors (pavor nocturnus) occur during non-REM sleep between ages 2 and 5 year^.^" Within hours after falling asleep, the child awakens frightened, tachycardic, and diaphoretic and may run in a frenzied state. During the 1- to 2minute episodes, the fearful child cannot be comforted. Somnambulism (sleepwalking) is another predominantly childhood disorder of non-REM sleep, often associated with night terrors and enuresis. T h e eyes are glassy and the child may merely sit up or walk about performing simple, automatic acts. Somniloquy (sleeptalking) often accompanies somnambulism and consists of garbled, monosyllabic utterances. Sleepwalking episodes last minutes and injury may occur. As with night terrors, there is usually no recollection of the spell upon a ~ a k e n i -n g . ~ ' Benign sleep jerks occur as normal individuals fall asleep and involve the legs, trunk, or, less often, the arms. These are not myoclonic seizures.

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or fatigue and diminished during sleep. Transient tics occur in up to 25% of schoolchildren; most often these are eye blinking or other facial movements." Tourette's syndrome consists of chronic motor and vocal tics and is often associated with obsessive-compulsive behavior^.^' Tics are sometimes misdiagnosed as focal motor seizures. Myoclonus is a sudden muscle jerk resulting from central nervous system dysfunction. Hallett39 classified subtypes of epileptic and nonepileptic myoclonus. Epileptic myoclonus is associated with short electromyographic bursts (

The differential diagnosis of epilepsy.

Neurolog Volume 10, Number 4 December 1990 0m.n Devinsky, M.D. The epilepsies are a group of heterogeneous disorders characterized by spontaneous,...
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