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Chapter 10: Focal Seizures in Infancy

J. Helen Cross

INTRODUCTION

Focal seizures are the most common seizure type presenting in childhood. They may present as the occurrence of a single seizure type, or as part of a wider spectrum of seizure types integral to an epilepsy syndrome. By definition and implication, such seizures arise from one area of the brain. The most recent proposal by the ILAE (The International League Against Epilepsy) defined a focal seizure "as one that originates within networks limited to one hemisphere. They may be discretely localised or more widely distributed and may also arise in subcortical structures. For each seizure type, ictal onset is consistent from one seizure to another, with preferential propagation patterns that can involve the contralateral hemisphere. In some cases however there is more than one network, and more than one seizure type, but each individual seizure type has a consistent site of onset."1

Focal seizures can then be described on the basis of semiology (the clinical presentation of the event), which depends on the area of brain origin and propagation pattern, both of which define the localization of seizure onset. By recognizing the clinical seizure pattern, with or without EEG confirmation, seizure onset may be attributed to one particular lobe (e.g., temporal lobe) or localized brain region (e.g., supplementary motor area). Further, they may be described according to whether consciousness (awareness) is retained (see Table 10–1). The terms "complex" and "simple" may be confusing; therefore, it has been recommended that these terms should no longer be used. The term "dyscognitive" has been proposed for impaired awareness (if this can be determined).1

TABLE 10–1.DESCRIPTORS OF FOCAL SEIZURES ACCORDING TO DEGREE OF IMPAIRMENT DURING SEIZUREa
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TABLE 10–1. DESCRIPTORS OF FOCAL SEIZURES ACCORDING TO DEGREE OF IMPAIRMENT DURING SEIZUREa

  • Without impairment of consciousness or awareness.

    • With observable motor or autonomic components.

      • This roughly corresponds to the concept of "simple" partial seizure.

      • "Focal motor" and "autonomic" are terms that may adequately convey this concept depending on the seizure manifestations).

    • Involving subjective sensory or psychic phenomena only.

      • This corresponds to the concept of an aura, a term endorsed in the 2001 Glossary.

    • With impairment of consciousness or awareness.

      • This roughly corresponds to the concept of complex partial seizure. "Dyscognitive" is a term that has been proposed for this concept.2

    • Evolving to a bilateral, convulsiveb seizure (involving tonic, clonic, or tonic and clonic components).

      • This expression replaces the term "secondarily generalized seizure."

aFor more descriptors that have been clearly defined and recommended for use. See Blume WT, Luders HO, Mizrahi E, Tassinari C, van Emde BW, Engel J Jr. Glossary of descriptive terminology for ictal semiology: Report of the ILAE Task Force on Classification and Terminology. Epilepsia 2001;42:1212–1218.

bThe term "convulsive" was considered a lay term in the Glossary; however, we note that it is used throughout medicine in various forms and translates ...

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