Seizures are a relatively common neurological disorder and may be seen in a wide range of clinical settings. Clinicians in multiple subspecialties should be competent in the identification, evaluation, and management of a first seizure episode as well as the recognition of seizure mimics. Decisions ranging from determining whether the seizure was provoked or unprovoked, investigating the etiology of unprovoked seizures, and initiating antiepileptic medications need to be approached in a logical, stepwise fashion. Unlike a first seizure episode, status epilepticus represents a true neurologic emergency. Prompt recognition and treatment are essential for ensuring optimal outcomes.

Comment: The history described above is typical of a first seizure episode. What is a seizure? Why might the patient have seized? What should you tell the family, and how do you evaluate such an event? These questions will be addressed in the subsequent chapter in which we will provide an approach to a first seizure episode.

Overview and definitions

Each year, there are more than one million visits to the ED across the country for evaluation of suspected seizure and about 10% of the general population will suffer a seizure at some point in their life.¹ Many of these patients and their families present to the hospital seeking help for a condition that is not only frightening to observe, but also associated with significant morbidity and mortality, social stigma, and substantial societal costs. It is estimated that the annual cost of epilepsy tops $12.5 billion, with misdiagnosis and poor treatment only adding to the overall expense.²

Definitions

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  The term “spell” is often used initially to describe a constellation of symptoms concerning for seizure until the history, physical examination, or other ancillary testing supports the diagnosis of seizure. There are several conditions that may mimic a seizure.

  
  
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  A seizure is a constellation of symptoms and signs that result from abnormal electrical discharges in the brain.

  
  
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  A provoked seizure is a seizure that occurs because of a specific cause, such as a significant metabolic derangement, drug or alcohol intoxication or withdrawal, or acute brain insult such as a stroke, encephalitis, or trauma.

  
  
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  Epilepsy is defined as recurrent unprovoked epileptic seizures due to a genetically determined or acquired brain disorder.³ A discussion of the evaluation and management of epilepsy is beyond the scope of this chapter.

  
  
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  Nonepileptic seizures (NES) are sudden changes in behavior that resemble epileptic seizures but are not associated with the abnormal electrical discharges in the brain that characterize epileptic seizures.

Provoked seizures

Provoked seizures account for about 40% of first-time seizures. In general, if the underlying etiology is corrected, a patient should not experience seizure recurrence, and thus they are not considered to have epilepsy. However, special care must be taken to ensure that the presumed provoking abnormality can account for the seizure. For instance, it would be unlikely for a sodium of 130 to provoke a seizure, whereas a sodium of 115 certainly may. Given that approximately 40–50% of individuals who suffer an unprovoked first-time seizure will experience a second, early identification and treatment of those most at risk for recurrent seizures is key to lowering the morbidity and mortality associated with this disorder.⁴

Clinical features of seizures and seizure mimics

Taking a seizure history

Differentiating seizures from seizure mimics requires a careful history and thorough evaluation.

Unless a patient’s spell is witnessed by the clinician, diagnosing a seizure can be challenging if not impossible. Not only can patients be amnestic for the spell in question, making an accurate account of what they experience difficult to obtain, but multiple seizure mimics can have similar features (Table 14-1). Additionally, there are multiple types of seizures (Table 14-2). Obtaining detailed information about the spell from as many reliable witnesses as possible is the first and perhaps most crucial step in making the diagnosis. A list of high-yield historical questions is included in Table 14-3.

After the initial history of the event is obtained, careful attention should also be paid to other elements of the history, including past medical history, medications, and any relevant family history. Prior insults to the central nervous system (CNS) can predispose a person to having future seizures, and a history of such an event may increase the likelihood that the spell was indeed a seizure. A large number of medications can also lower the seizure threshold, as can withdrawal of certain medications. While a comprehensive list of medications is beyond the scope of this chapter, any new medications or recent changes in medication (including dose) should be carefully scrutinized as these are more likely to precipitate new events than medications the patient has been taking for years. Because seizures related to mediations tend to be generalized, focal-onset seizures should prompt a more extensive search for the cause even if the patient has taken a new medication known to be associated with seizures.

A family history of seizures may also be highly suggestive of seizure in the right clinical context. Epilepsy syndromes tend to run in families, being passed down in a variety of fashions (dominant, recessive, sex-linked) and with similar clinical features, such as age of onset and clinical characteristics.

Prodrome

Before the event in question, patients with seizure may describe an unusual or unpleasant sensation such as a smell, feeling of déjà vu, nausea, or a rising gastric sensation (Table 14-4). These are, in fact, very focal seizures that affect enough brain to produce symptoms but not enough to interfere with consciousness and are otherwise known as “auras.” The presence of an aura is suggestive of seizure as the cause of a patient’s spell. Often, however, patients do not have any warning before a seizure results in consciousness impairment. Similarly, individuals with vasovagal or cardiogenic syncope may describe a light-headed sensation, tunneling of the vision, palpitations, or no warning at all prior to loss of consciousness. Migraine sufferers may report flashing lights in the peripheral visual field, while delirious or encephalopathic patients generally report an antecedent illness or a slowly progressive course beginning with only occasional forgetfulness. Patients with nonepileptic behavioral events (NEBMs) occasionally describe a feeling of anxiety, palpitations, or some initial stressful event prior to losing consciousness, but more often report complete amnesia for the entire event.

Loss of consciousness

Loss of awareness is one of the characteristic features of focal seizures, while loss of consciousness occurs in generalized seizures when the abnormal electrical discharge spreads to involve both cerebral hemispheres. Loss of consciousness is also a hallmark feature of syncope. Loss of consciousness is rarely seen in stroke or transient ischemic attack (TIA). Exceptions include bilateral thalamic infarctions or a basilar artery thrombosis. In patients with NEBM, they may appear to lose awareness, but more sophisticated diagnostic testing or physical examination generally demonstrates preservation of consciousness.

Duration of symptoms

The actual ictus in a seizure is typically brief, with the average seizure lasting seconds and the majority lasting 1–2 minutes. It is not uncommon, however, for family members to report a duration of many minutes. This is generally because they are estimating the time from onset until when the patient regained some level of consciousness, which may include a portion of the postictal period. Additionally, the fear that accompanies watching someone suffer a seizure may make the event seem much longer than it is.

In contrast to seizures, a syncopal event is typically short lived. Once blood flow to the brain is reestablished, consciousness returns fairly quickly, typically on the order of a few seconds. Migraines commonly last several hours, although the symptoms may fluctuate throughout the entire event. In a transient ischemic attack, symptoms may only last a few seconds to many minutes while delirium or encephalopathy may last hours to days, depending on the underlying etiology. NEBMs commonly last several minutes and may even occur over several hours. A characteristic feature of NEBMs is that they tend to start and stop.

Abnormal movements

When imagining a seizure, most lay people think of limbs and abdomen flailing. In most cases, however, movements resulting from a generalized seizure are much more stereotyped and rhythmic. Common abnormal movements encountered during a seizure include tonic movements, in which muscles stiffen and the arms flex, and clonic movements, in which the arms and legs begin to jerk symmetrically in a rapid and rhythmic fashion. Focal seizures, on the other hand, may consist of only one group of muscles or one area of the body jerking in a rhythmic fashion. Alternatively, they may manifest with purely autonomic features or abnormal behaviors (Table 14-5).

Syncope is often accompanied by abnormal movements, so-called “convulsive syncope,” but these movements are typically myoclonic in nature—brief, arrhythmic, and multifocal—lacking the coordination of the tonic–clonic movements in seizure. Similarly, encephalopathy or delirium may be accompanied by myoclonic movements, particularly if a metabolic disturbance is responsible for the altered mentation. One of the most common features of NEBMs are abnormal movements. These movements, however, tend to be erratic, multifocal, and arrhythmic. Characteristic features of NEBEs include:

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  Forced eye closure

  
  
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  Forward pelvic thrusting

  
  
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  Side-to-side rolling

  
  
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  Start-stop quality that reflects developing fatigue and the need for rest between strenuous movements

  
  
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  Vocalizations during the convulsions, as opposed to at the beginning, which is commonly seen in epileptic seizures

  
  
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  Biting of the tip of the tongue

  
  
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  Absence of autonomic signs

  
  
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  Rapid awakening and reorientation (lack of a postictal phase)

  
  
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  Take place in the presence of witnesses

  
  
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  Rarely associated with more than small abrasions despite multiple reports of falling

Generalized seizures are often accompanied by additional findings, by history or examination. It is not uncommon for patients who have suffered a seizure to bite their tongue, and a bite on the lateral surface of the tongue is far more specific for seizure than a bite on the tip of the tongue. The loss of bowel or bladder control is another characteristic of a generalized seizure rather than a mimic, although the absence of this does not exclude a seizure. Syncope may be situation-dependent, such as with the sight of blood. Careful history taking may reveal multiple past syncopal episodes in similar situations. Migraines are often accompanied by the typical headache. Delirium tends to wax and wane, typically over hours to days, with periods approaching lucidity between those of complete disorientation. NEBMs tend to occur when there are witnesses and, despite multiple reports of falling, are rarely associated with injuries more significant than a small abrasion.

Postictal phase

Generalized seizures are typically followed by a postictal phase consisting of extreme fatigue and confusion that often lasts several hours. Most of the stroke mimics lack such a defining feature, and the patient generally returns to baseline immediately after the event in question. Patients with NEBMs often describe a postictal period of confusion or lethargy but, in contrast to that following a generalized seizure, this period tends to be relatively brief.

Evaluation of the first seizure episode

Why evaluate the seizure?