Seizures are categorized into two major types, depending on the presumed source: partial (focal) seizures or generalized seizures (Table 20.1).

In partial (focal) seizures, the initial discharge comes from a specific part of the brain. Such patients have symptoms that depend on the area of cortex involved. Thus, patients whose seizures begin with their right hand shaking or with an aura of smelling “burned candy” have a partial seizure disorder, attributable to a lesion in the frontal or temporal lobe, respectively. Partial
seizures with impairment of consciousness are known as complex partial seizures. Remember, a seizure can begin focally and then generalize. This may happen so quickly that it is impossible to see the focality clinically, and the patient can recall no aura. Nonetheless, the electroencephalogram (EEG) usually shows the focality, and historical clues (brain tumor, arteriovenous malformation [AVM]) may suggest a focal origin. Partial seizure disorders are usually secondary to local pathology (e.g., trauma, tumor, vascular lesions, or congenital abnormalities).

It is important to recognize that partial complex seizures may be manifest only by unusual and paroxysmal changes in behavior, without loss of consciousness or convulsive motor activity. This is especially true in the elderly, in which the incidence of epilepsy is increasing dramatically, and in which the manifestations of seizures can be unusual.

In generalized seizures, there are no focal sites of seizure origin. There is no aura, and there are no focal features during the seizure. Examples of generalized seizures include absence seizures (previously called petit mal) and idiopathic tonic–clonic seizures (previously called grand mal). A tonic–clonic seizure is a major motor seizure involving all extremities, and having tonic (stiffening) and clonic (rhythmic jerking) movements. Myoclonic jerks (rapid individual muscle movements) also may be seen in primary generalized epilepsy, often as a syndrome in teenage years, combined with absence seizures and rare tonic–clonic seizures (juvenile myoclonic epilepsy of Janz).

Note: Seizures may follow unusual stress (“precipitated convulsions”) and are not considered epilepsy.

Establish whether the seizure disorder is focal or generalized.

Is there a history of unusual behavior, with or without loss of consciousness, which is not explained by other medical diagnoses?
Does the patient remember the event? Is there any retrograde amnesia? Is there confusion after the event?

Drug withdrawal (from alcohol, barbiturates, and other sedatives) is a common cause of seizures in adults. Alcohol withdrawal seizures occur 12 to 48 hours after the cessation of drinking (see Chapter 27). Alcoholics with post-traumatic epilepsy secondary to frequent falls may have an exacerbation of seizures when intoxicated.

Exacerbation of a known seizure disorder is common. Persons with a controlled seizure disorder, who come to the hospital because of a recurrence, usually have: