Epilepsy is characterized by recurrent seizures due to a genetically inherited or acquired brain disorder. The prevalence of epilepsy increases with age, especially after 65, and occurs in 2%–5% of adults in general. Even patients with epilepsy under relative control can experience problems with depression, driving, employment, and insurance.
Epilepsy has many possible causes. Seizures result from synchronized electrical activity of neuronal networks in the cerebral cortex. Any disturbance of normal neuronal activity, including injury, infection, and abnormal brain development, can lead to seizures. Cerebral vascular disease is the most common cause in older adults; however, about half of all seizures have no identifiable cause. Seizures may develop because of an abnormality in brain wiring, an imbalance of neurotransmitters, or some combination of these factors. Epilepsy can also be associated with a variety of developmental and metabolic disorders, including cerebral palsy, neurofibromatosis, tuberous sclerosis, and autism.
Typically, seizures are divided into 2 major categories: partial and generalized. Partial seizures occur in only 1 part of the brain and are further divided into simple (without impairment of consciousness) and complex (with impairment of consciousness). Symptoms of simple partial seizures (also called auras) depend on the part of the brain from which the seizures originate and include motor symptoms, sensory symptoms (which can resemble a migraine aura), and even autonomic symptoms. Complex partial seizures are the most common type of seizures in adults with epilepsy. During the seizure, patients may appear to be awake but do not interact with others around them and do not respond normally to instructions or questions. They often stare into space and either remain motionless or engage in repetitive behaviors, called automatisms, such as facial grimacing or gesturing.
Generalized seizures cause impaired consciousness and abnormal activity in both hemispheres at the onset of the seizure. These events may follow partial seizures. They can be nonconvulsive (absence, or “petit mal”) or convulsive (tonic–clonic, or “grand mal”; or some variation of tonic–clonic). Absence seizures almost always begin in childhood or adolescence and are frequently familial, suggesting a genetic cause. During seizures, some patients make purposeless movements, such as jerking an arm or rapidly blinking their eyes. Others have no noticeable symptoms except for brief periods of “absence.” Childhood absence epilepsy often stops when the child reaches puberty. A generalized tonic–clonic seizure is the most dramatic, in that it begins with an abrupt alteration in consciousness, sometimes in association with a scream or shriek. All of the muscles stiffen, and the patient may become cyanotic during the tonic phase. Within a short time, the muscles begin to jerk and twitch for 1–2 minutes, and then the patient goes into a deep sleep.
The end of a seizure is referred to as the postictal period and signifies the recovery period for the brain. This period may last from several seconds up to a few days, though typically no more than a few hours. Postictal paresis (Todd paralysis) is a transient focal motor deficit that lasts for hours or, in rare cases, days after an epileptic convulsion. It is thought to be related either to neuronal exhaustion (from electrical overactivity during the seizure) or to active inhibition.
Electroencephalography (EEG) is the most common diagnostic test for epilepsy, although a normal EEG result does not rule out the disorder. Computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), and single-photon emission computed tomography (SPECT) are useful tools for revealing abnormalities in the brain that cause epilepsy. Patients with epilepsy have a higher overall mortality rate that is about twice that of the general global population. Occurrence of other associated mood disorders, particularly depression, is also higher in these patients.
Currently available treatments help control seizure activity in 80% of patients with epilepsy. The medication used is determined by the type of epilepsy, comorbidities, age of the patient, and potential drug interactions. This latter concern specifically applies to the medication’s effect on patients who are concurrently being treated with warfarin or certain antibiotics, or who are taking oral contraceptives. For generalized tonic–clonic seizures, the first-line therapy includes valproic acid, lamotrigine, and topiramate. For partial seizures, carbamazepine, phenytoin, oxcarbazepine, or ethosuximide are often used (especially in children). To minimize side effects, monotherapy is the goal; however, use of a second agent is sometimes necessary to control breakout seizures. Adverse effects vary; they may include nausea, rash, anorexia, somnolence, dizziness, and confusion. The neurologic effects often become the dose-limiting factor. Some of these drugs used for the treatment of epilepsy can also promote hyperlipidemia, which may increase the risk of cardiovascular disease. Rare, but serious, drug reactions include Stevens-Johnson syndrome and toxic epidermal necrolysis (TEN).
When medications inadequately control seizure activity, surgery is a potential option. The most commonly performed procedure for epilepsy is removal of a seizure focus via lobectomy or lesionectomy. Other, less common surgical procedures for epilepsy include multiple subpial transections, corpus callosotomy, and hemispherectomy. An implanted vagus nerve stimulation (VNS) device can be effective in helping to control seizures in children when medication alone is not sufficient.
Fountain NB, Van Ness PC, Swain-Eng R, Tonn S, Bever CT Jr; American Academy of Neurology Epilepsy Measure Development Panel and the American Medical Association-Convened Physician Consortium for Performance Improvement Independent Measure Development Process. Quality improvement in neurology: AAN epilepsy quality measures. Report of the Quality Measurement and Reporting Subcommittee of the American Academy of Neurology. Neurology. 2011;76(1):94–99.
Noe KH. Seizures: diagnosis and management in the outpatient setting. Semin Neurol. 2011;31(1):54–64.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.