Partial Epilepsies

Updated: Oct 30, 2017
  • Author: Alberto Figueroa Garcia, MD; Chief Editor: Helmi L Lutsep, MD  more...
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Overview

Background

Partial epilepsies are epileptic disorders in which seizure semiology or findings on investigation disclose localized origin of seizures. In children, cortical dysplasias and low-grade neoplasms are the most commonly identified causes.

Partial epilepsies represent the most common type of adult-onset epilepsy. Most adult-onset localization-related epilepsies do not have an identifiable etiology (ie, neuroimaging studies are most often normal). When a cause is found, it can include various structural lesions (eg, traumatic scars, neoplasms, vascular malformations, strokes, neuronal heterotopias).

Obtaining a description of the seizures from the patient and any witnesses is critical. The description needs to include a description of the patient’s state of consciousness during the seizure, to determine whether the seizure is a simple or complex partial seizure (see Clinical Presentation). Further evaluation, which may include neuroimaging, is important for determining the specific disorder, in order to determine prognosis and guide therapy (see Workup).

Partial epilepsies are generally treated with antiepileptic drugs (AEDs). Nonpharmacologic treatments in certain refractory cases include surgery and dietary modification (see Treatment and Management).

Go to Epilepsy and Seizures for a general overview of this topic.

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Pathophysiology

Most partial epilepsies are the result of a localized brain abnormality, even though in most patients the abnormality cannot be seen with imaging techniques.

Only a few partial epilepsies are genetic; most are lesional. Unfortunately, in the current classification, they are referred to as idiopathic. The term idiopathic is often misunderstood in this setting. While generally idiopathic means "of unknown cause," idiopathic epilepsies are not truly of unknown cause. This terminology most likely will be corrected in the upcoming classification system of the International League Against Epilepsy (ILAE). Idiopathic epilepsies are determined genetically and have no apparent structural cause, with seizures as the only manifestation of the condition.

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Etiology

Most partial epilepsies are caused by a localized brain abnormality, which may or may not be visible on imaging studies. If the cause is found, the epilepsy is said to be symptomatic. If imaging studies are normal, the cause remains elusive and the disorder is said to be cryptogenic. Although imaging studies often have negative results, advances in neuroimaging techniques have resulted in the identification of lesions in increasing numbers of cases. Such lesions include low-grade tumors, hippocampal sclerosis, and subtle cortical dysplasias.

Because of dramatic differences in electroclinical semiology and management, localization-related epilepsies usually are divided into mesiotemporal and neocortical. The most common localization-related epilepsy in adults is mesiotemporal lobe epilepsy, but, in neonates and young children, this is less common than neocortical epilepsy.

The most common cause of temporal lobe epilepsy in candidates for epilepsy surgery in adults is hippocampal sclerosis, while in children, etiologies are dominated by cortical dysplasias and low-grade neoplasms.

Most adult-onset localization-related epilepsies do not have an identifiable etiology (ie, MRI is most often normal); this is well known. When a cause is found, it can include various structural lesions (eg, traumatic scars, neoplasms, vascular malformations, strokes, neuronal heterotopias).

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Epidemiology

The prevalence of epilepsy is approximately 1% of the population, both in the United States and internationally. Most adult-onset epilepsies are partial epilepsies. Males and females are equally affected. The age-related incidence follows a U-shaped curve, with a peak in the first year of life and an increase during the sixth and seventh decades. (See the image below.)

This graph illustrates the 2 peaks of incidence of This graph illustrates the 2 peaks of incidence of epilepsy: early and late in life.
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Prognosis

In the United States, the mortality rate from epilepsy decreased from 0.8 deaths per 100,000 population in 1979 to 0.7 deaths per 100,000 population in 1986; it was 0.6 deaths per 100,000 persons for white males and females but 1.7 deaths per 100,000 persons for black males and 1 death per 100,000 persons for black females. No specific data are available for partial epilepsy.

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Patient Education

For patient education information, see the Brain and Nervous System Center, as well as Epilepsy.

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