After studying this chapter, the student should be able to:
Define the terms seizure and epilepsy.
Classify different seizure types and epilepsy syndromes.
Understand how epilepsy is diagnosed.
Identify the utility of different types of electroencephalogram (EEG) studies.
Know the main treatments for epilepsy, both medical and surgical.
Recognize status epilepticus as a neurologic emergency.
A seizure is a transient occurrence of signs and/or symptoms due to abnormal, excessive, or synchronous neuronal activity in the brain. Seizures can be caused by a wide variety of provoking insults, including electrolyte disturbances, brain injury/insult, and fevers in children, or can occur completely unprovoked (Table 27–1). After a single unprovoked seizure, only about 30% of patients will go on to have another seizure. After 2 seizures have occurred, the recurrence risk for additional seizures is approximately 75%.
TABLE 27–1Common causes of new-onset seizures. |Favorite Table|Download (.pdf) TABLE 27–1 Common causes of new-onset seizures.
Primary neurologic disorders
Benign febrile convulsions of childhood
Stroke or vascular malformations
Global cerebral ischemia
Epilepsy is a disorder of the brain characterized by a predisposition to generate recurrent unprovoked epileptic seizures. It is defined by any of the following conditions: (1) at least 2 unprovoked seizures occurring >24 hours apart; (2) 1 unprovoked seizure and a high probability of further seizures occurring over the next 10 years because of an underlying predisposing condition; or (3) diagnosis of an epilepsy syndrome.
Approximately 2 million Americans and >65 million people worldwide have epilepsy. The prevalence of epilepsy in the general population is about 1%. Each year, approximately 300,000 people have their first seizure and 150,000 new cases of epilepsy are diagnosed. The incidence of epilepsy is highest in young children and older adults. Risk factors for developing epilepsy include intellectual or developmental delay, family history of seizures, cerebral palsy, autism, hypoxia, stroke, head trauma, central nervous system infection, intracranial hemorrhage, dementia, brain tumors, and tubers or other brain malformations.
Risk of death is up to 3 times higher in patients with epilepsy than the general population. Causes of death in epilepsy include injury, drowning, suicide, status epilepticus, and sudden unexpected death in epilepsy (SUDEP). SUDEP is defined as a sudden, unexpected, nontraumatic, nondrowning, witnessed or unwitnessed death while in a reasonable state of health in a person who has epilepsy and no other obvious or structural cause. SUDEP is the leading cause of epilepsy-related death, with >1 out of 1000 ...