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A seizure is a paroxysmal event due to abnormal excessive or synchronous neuronal activity in the brain. Epilepsy is diagnosed when there are recurrent seizures due to a chronic, underlying process.
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APPROACH TO THE PATIENT: Seizure
Seizure classification: Essential for diagnosis, therapy, and prognosis (Table 181-1). Seizures are focal or generalized: focal seizures originate in networks limited to one cerebral hemisphere, and generalized seizures rapidly engage networks distributed across both hemispheres. Focal seizures are further divided based on presence or absence of cognitive impairment.
Generalized seizures may occur as a primary disorder or result from secondary generalization of a focal seizure. Tonic-clonic seizures (grand mal) cause sudden loss of consciousness, loss of postural control, and tonic muscular contraction producing teeth-clenching and rigidity in extension (tonic phase), followed by rhythmic muscular jerking (clonic phase). Tongue-biting and incontinence may occur during the seizure. Recovery of consciousness is typically gradual over many minutes to hours. Headache and confusion are common postictal phenomena. In absence seizures (petit mal) there is sudden, brief impairment of consciousness without loss of postural control. Events rarely last longer than 5–10 s but can recur many times per day. Minor motor symptoms are common, while complex automatisms and clonic activity are not. Other types of generalized seizures include tonic, atonic, and myoclonic seizures.
Etiology: Seizure type and age of pt provide important clues to etiology (Table 181-2).
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Careful history is essential since diagnosis of seizures and epilepsy is often based solely on clinical grounds. Differential diagnosis (Table 181-3) includes syncope or psychogenic seizures (“pseudoseizures”). General examination includes search for infection, trauma, toxins, systemic illness, neurocutaneous abnormalities, and vascular disease. A number of drugs lower the seizure threshold (Table 181-4). Asymmetries in ...