Epilepsy - Introduction

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Experts are finding, however, that these categories do not actually reflect what is now known about the brain's anatomy. For example, the words "partial" and "generalized" suggest that seizures either involve only part of the brain or are widespread. However, a number of events in the brain occur with either type, muddying these distinctions. Researchers are now in the process of making clearer definitions and terms that reflect what actually is happening in the brain.

Improved definitions of terms and new diagnostic technologies, including advanced imaging and genetic testing, have spawned new classification systems that better define specific epilepsies. The evolving methods may help researchers more accurately focus on specific epilepsies and allow doctors to make more appropriate therapeutic decisions. For example, some professional groups now suggest that epilepsies be classified in the following five ways:

• Type of seizure (partial or generalized)
• Description of the seizure onset and evolution
• Specific syndromes that are associated with one or more seizure types (however, not all seizures will be part of a syndrome)
• Specific causes of the seizures, if known
• Degree of impairment

Partial Seizures (also called Focal Seizures)

Partial, or focal, seizure is the more common type of epilepsy, and is generally defined as a disorder of neurons that starts on one side of the brain. The seizures are currently subcategorized as "simple" or "complex partial."

• Simple Partial Seizures. A person with a simple partial seizure (sometimes known as Jacksonian epilepsy) does not lose consciousness, but may experience confusion, jerking movements, tingling, or odd mental and emotional events. Such events may include deja vu, mild hallucinations, or extreme responses to smell and taste. After the seizure, the patient usually has temporary weakness in certain muscles.
• Complex Partial Seizures. Slightly over half of seizures in adults are complex partial type. About 80% of these seizures originate in the temporal lobe, the part of the brain located close to the ear. Disturbances there can result in loss of judgment, involuntary or uncontrolled behavior, or even loss of consciousness. About 20% of these patients have seizures that start in the brain's frontal lobes. Prior to the actual seizure, people sometimes experience a warning sign, known as an aura, which can be a visual or auditory hallucination, an odd odor or a feeling of warmth. They may lose consciousness briefly and appear to others as motionless with a vacant stare. Emotions can be exaggerated; some sufferers even appear to be drunk. After a few seconds, a patient may begin to perform repetitive movements, such as chewing or smacking of lips. Episodes usually last no more than 2 minutes. They may occur infrequently, or as often as every day. A throbbing headache may follow a complex partial seizure.