Focal (Partial) Seizures

The history and neurologic examination are the cornerstones of neurologic diagnosis. When assessing when a patient may have had a seizure, it is important to obtain a description of a paroxysmal change in behavior, whether there was a loss of consciousness, the duration of the spell, and whether stimuli were encountered that might precipitate a seizure. A family history of epilepsy should always be ascertained. Of particular importance in the history is the description of the initial signs or symptoms. For example, the approach to a patient with an aura before a GTC is quite different from the patient who has a GTC without an aura. In the former case, it is likely that the patient has a focal onset to the seizure, increasing the chances that there is a structural lesion responsible for the seizure, while in the latter instance, it is likely the patient has a seizure-inducing stimulus, such as low blood sugar or perhaps an underlying genetic condition. Postictal features can also be helpful. Absence seizures of childhood are brief, typically lasting 30 seconds or less, and have a rapid offset, with the child quickly returning to normal mental status. Complex partial seizures are of longer duration, lasting 30 seconds to several minutes, and typically have some degree of confusion and tiredness after the event.

There are many episodic disorders that resemble seizures. Episodes such as night terrors, breath-holding spells, or syncope may resemble epileptic seizures. The timing of the event is important. When nocturnal, epileptic seizures typically occur in the early morning hours, while sleep disorders such as night terrors typically occur several hours after the child falls asleep. A young child for whom the event always occurs in association with provoked crying likely has breath-holding spells. Individuals who feel light-headed and clammy before losing conscious likely have syncope rather than epilepsy. If there is doubt about the diagnosis, it is usually better to wait before beginning therapy.

Seizures are classified into two major categories: focal and generalized. Focal seizures originate within a localized region of the brain, and may evolve into generalized convulsions. Generalized seizures rapidly engage both hemispheres of the brain. Generalized seizures are further classified into tonic, clonic, tonicclonic, absence, myoclonic, and atonic.

FOCAL (PARTIAL) SEIZURES

Focal seizures originate within networks of a limited region of the brain, often confined to one hemisphere. They can occur at any age. Focal seizures may be classified further into those without impairment of consciousness or awareness (simple partial seizures) and those with impairment of consciousness or awareness (complex partial seizures). Seizures without impairment of consciousness or awareness can be further subdivided into seizures with (1) observable motor or autonomic components or (2) subjective sensory or psychic phenomenon. The signs or symptoms of focal seizures depend on the location of the focus within the brain. Seizures involving the motor cortex most commonly consist of rhythmic or semirhythmic clonic movements of the face, arm, or leg. There is usually no difficulty in diagnosing this type of seizure. Seizures with somatosensory, autonomic, and psychic symptoms (hallucinations, illusions, déjà vu) may be more difficult to diagnose.

Most commonly, psychic symptoms occur as a component of a focal seizure with impaired consciousness or responsiveness. Focal seizures with impairment of consciousness or awareness (complex partial seizures), formerly termed temporal lobe or psychomotor seizures, are one of the most common seizure types encountered in both children and adults. The beginning of the focal seizure may serve as a warning to the patient (i.e., aura) that a more severe seizure is pending. It is important to recognize that the aura may enable the clinician to determine the cortical area from which the seizure is beginning.

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