eMedicine Specialties > Neurology > Seizures and Epilepsy

First Seizure in Adulthood, Diagnosis and Treatment

Author: William J Nowack, MD, Associate Professor, Epilepsy Center, Department of Neurology, University of Kansas Medical Center
Contributor Information and Disclosures

Updated: Aug 29, 2006

Introduction

Background

Many diseases can cause paroxysmal clinical events. The correct diagnosis of the paroxysmal event is necessary to provide correct treatment. If the event is an epileptic seizure, the seizure type and associated clinical, electroencephalographic (EEG), and neuroimaging findings assist in determining the risk of seizure recurrence and the possible need to begin anticonvulsant therapy. Yet, the correct diagnosis is often missed. In 1998, Scheepers et al found 49 patients with an incorrect diagnosis and 26 patients with an uncertain diagnosis among 214 patients with a diagnosis of epilepsy.

This article focuses on 2 related questions:

• Is the spell truly epileptic?
• If the event is epileptic, is it likely to recur?

In a 1999 report, Davidson describes a similar approach to the patient with a first seizure.

• Is it epilepsy?
• What kind of epilepsy?
• What is the cause?

This article describes the common clinical features of patients with a first seizure, risk factors for seizure recurrence, and a general approach to patient management.

Pathophysiology

The definitions of the following terms come from the International League Against Epilepsy (ILAE) Guidelines (Jallon, 1993; Roger, 1989).

A nonepileptic event is a clinical event presumed to be unrelated to abnormal and excessive neuronal discharge. An example of a nonepileptic event is syncope. Decreased cardiac output causes decreased cerebral perfusion, and this results in loss of consciousness.

An epileptic seizure is a clinical event presumed to result from an abnormal and excessive neuronal discharge. The clinical symptoms are paroxysmal and may include impaired consciousness and motor, sensory, autonomic, or psychic events perceived by the subject or an observer.

Epilepsy occurs when 2 or more epileptic seizures occur unprovoked by any immediately identifiable cause. The seizures must occur more than 24 hours apart. In epidemiologic studies, an episode of status epilepticus is considered a single seizure. Febrile seizures and neonatal seizures are excluded from this category.

Idiopathic epilepsy describes epilepsy syndromes with specific age-related onset, specific clinical and electrographic characteristics, and a presumed genetic mechanism.

Epileptic seizures are classified as cryptogenic or symptomatic. Cryptogenic seizure is a seizure of unknown etiology. This type of seizure is not associated with a prior CNS insult known to increase the risk of developing epilepsy. It does not conform to the criteria for the idiopathic or symptomatic categories. Previous studies use the term idiopathic to describe a seizure of unknown etiology. However, current ILAE guidelines discourage use of the term idiopathic to describe a seizure of unknown etiology.

Symptomatic seizure is a seizure caused by a previously known or suspected disorder of the CNS. This type of seizure is associated with a prior CNS insult known to increase the risk of developing epilepsy.

An acute symptomatic seizure is one that occurs following a recent acute disorder such as a metabolic insult, toxic insult, CNS infection, stroke, brain trauma, cerebral hemorrhage, medication toxicity, alcohol withdrawal, or drug withdrawal. An example of an acute symptomatic seizure is a seizure that occurs within 1 week of a stroke or head injury.

A remote symptomatic seizure is a seizure that occurs more than 1 week following a disorder that is known to increase the risk of developing epilepsy. The seizure may occur a long time after the disorder. These disorders may produce static or progressive brain lesions. An example of a remote symptomatic seizure is a seizure that first occurs 6 months following a traumatic brain injury or stroke.

Seizures are also classified as provoked or unprovoked. A provoked seizure is an acute symptomatic seizure. An unprovoked seizure is a cryptogenic or a remote symptomatic seizure.

Frequency

United States

In 1997, Moore-Sledge reported that the annual incidence of adult-onset seizures in the United States is 84 cases per 100,000 population and that about 6% of the US population experience a nonfebrile seizure sometime during life. She estimates that approximately 50 of each 84 patients develop epilepsy.

International

In European studies, the incidence of first unprovoked seizures ranges from 26-70 cases per 100,000 persons. Beghi et al in a 1997 article attributed the variability to differences in methodology and definitions. The rates were similar in different geographic areas despite technical differences in the studies.

Mortality/Morbidity

The patient who develops recurrent unprovoked seizures has the same mortality and morbidity rates as other patients with epilepsy.

Race

Racial differences have not been studied.

Sex

Most authors report a small-to-moderate preponderance of men in their studies of first seizures in adults (van Donselaar, 1992; Musicco, 1997; Hopkins, 1988; King, 1998).

• In 1986, Annegers et al found a slight overall preponderance of women. Their etiologic categories were neurologic deficit from birth, remote symptomatic, and no known prior etiology. They identified a preponderance of men in the group with neurologic deficit from birth, no sex preponderance in the group with remote symptomatic seizures, and a slight preponderance of women in the group with no known prior etiology. These authors did not determine if these sexual differences were statistically significant.
• Among patients who had an initial generalized tonic-clonic seizure, Bora et al found that only 45.5% were men (Bora, 1995). Patients with partial seizures and structural lesions proven on CT scan were excluded from this study.

Age

• In a study of consecutive patients aged 2 years or older, the age distribution for a first unprovoked seizure was the following (Musicco, 1993):
  • Younger than 16 years - 28%
  • Aged 16-60 years - 66%
  • Older than 60 years - 6%
• Among adults, young adults are affected most often.
  • In a study of patients aged 15 years and older, the mean age of first unprovoked seizure was 38 years (van Donselaar, 1992).
  • In a study of patients 16 years and older, the most frequently affected group was aged 20-29 years (Hopkins, 1988).

Clinical

History

The following information should be obtained in the history:

• Patient's age should be recorded.
• If a family history of seizures is noted, the clinical epilepsy syndrome of the affected family member should be determined.
• Ask about a history of any previous provoked seizure.
• Determine if the first seizure was status epilepticus.
• Ask the time of day of the seizure occurrence.
• Identify any symptoms that may indicate a nonepileptic event, such as convulsive syncope, syncope, transient ischemic attack, transient global amnesia, migraine, sleep disorder, movement disorder, vertigo, or nonepileptic psychogenic seizure (pseudoseizure).
  • Because of the frequency with which nonepileptic seizures occur, the first step should be to rule out nonepileptic events. Leppik estimates that about 9% of the population will have a seizure of some sort in their lifetime, and he estimates that about two thirds of these are nonepileptic seizures while the remainder are epileptic seizures.
  • Kostopoulos and coworkers (2003) studied 350 patients from the Maastricht and surroundings in a population-based prospective study. The patients were all older than 14 years and had been diagnosed with a suspected first seizure. Kostopoulos and coworkers divided the patients into 3 groups: 49.7% with unprovoked (presumed epileptic) seizures, 22.3% with nonepileptic seizures of organic origin, and 18% with nonepileptic seizures of psychogenic origin. Discriminative features for epileptic seizures were postictal confusion longer than 1 minute, epileptiform EEG, and abnormal neuroimaging. For nonepileptic seizures, a history of hypertension and provoking factors, such as exercise or warmth, was present. For psychogenic seizures, a history of febrile seizures; treatment by a psychiatrist or psychologist; and presentiment of the seizure, such as choking and palpitations, was present.
• Seek a possible etiology (see Causes).

Physical

• The neurologic examination should be directed at finding clinical evidence of a focal brain lesion.
• A general physical examination should be performed to exclude a nonneurologic cause of the seizure (Moore-Sledge, 1997).

Causes

• Epileptic seizure
  • Prenatal, perinatal, or postnatal complications of pregnancy and delivery
  • Febrile seizure: Distinguish a complex febrile seizure from a simple febrile seizure.
  • Cerebrovascular disease such as cerebral infarction, cerebral hemorrhage, and venous thrombosis
  • Head trauma: Head trauma is more significant when it occurs with loss of consciousness lasting longer than 30 minutes, posttraumatic amnesia lasting longer than 30 minutes, focal neurologic findings, or neuroimaging findings suggesting a structural brain injury.
  • CNS infections such as meningitis or encephalitis
  • Neurodegenerative diseases
  • Autoimmune disease
  • Brain neoplasm
  • Genetic diseases
  • Drug intoxication, drug withdrawal, or alcohol withdrawal
  • Metabolic medical disorders such as uremia, hypoglycemia, hyponatremia, and hypocalcemia
• Nonepileptic events
  • Transient ischemic attack
  • Migraine
  • Sleep disorders
  • Transient global amnesia
  • Movement disorder
  • Paroxysmal vertigo
  • Convulsive syncope: Decreased cardiac output causes reduced cerebral perfusion with loss of consciousness and convulsive motor activity. In 1998, Scheepers et al found that cardiovascular disease was the most common diagnosis among patients whose conditions were initially misdiagnosed as epilepsy. Using a comprehensive battery of cardiovascular tests in a population of patients diagnosed with epilepsy, in 2000 Zaidi et al found alternative cardiovascular diagnoses in 41%.
  • Psychiatric disorders such as conversion disorder (psychogenic seizures, pseudoepileptic seizures, pseudoseizures)
  • Malingering

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