Epilepsy
Also known as seizure disorder, epilepsy is a condition of the brain characterized by a susceptibility to recurrent seizures—paroxysmal events associated with abnormal electrical discharges of neurons in the brain. Epilepsy probably affects 0.5% to 2% of the population and usually occurs in patients younger than age 20. About 80% of patients have good seizure control with strict adherence to prescribed treatment. In most patients, the condition doesn’t affect intelligence.
Causes
About half the cases of epilepsy are idiopathic. No specific cause can be found, and the patient has no other neurologic abnormalities. Nonidiopathic epilepsy may be caused by:
genetic abnormalities, such as tuberous sclerosis and phenylketonuria
perinatal injuries
metabolic abnormalities, such as hypocalcemia, hypoglycemia, and pyridoxine deficiency
brain tumors or other space-occupying lesions
infections, such as meningitis, encephalitis, or brain abscess
traumatic injury, especially if the dura mater was penetrated
ingestion of toxins, such as mercury, lead, or carbon monoxide
stroke.
Researchers also have detected hereditary EEG abnormalities in some families, and certain seizure disorders appear to have a familial incidence.
Complications
Associated complications that may occur during a seizure include anoxia from airway occlusion by the tongue or vomitus and traumatic injury. Such traumatic injury could result from a fall at the onset of a generalized tonic-clonic seizure; the rapid, jerking movements that occur during or after a generalized tonic-clonic seizure; or a fall or sudden movement sustained while the patient is confused or has an altered level of consciousness.
Assessment
Depending on the type and cause of the seizure, signs and symptoms vary. (See Differentiating among seizure types.) If the assessment is performed when the patient isn’t having a seizure, and the cause is idiopathic, physical findings may be normal. If the seizure is associated with an
underlying problem, the patient’s history and a physical examination should reveal signs and symptoms of the causative condition (unless the seizure was caused by a brain tumor, which may produce no other symptoms).
underlying problem, the patient’s history and a physical examination should reveal signs and symptoms of the causative condition (unless the seizure was caused by a brain tumor, which may produce no other symptoms).
Differentiating among seizure types
The hallmark of epilepsy is recurring seizures, which can be classified as partial or generalized. Some patients may be affected by more than one type of seizure.
Partial seizures
Arising from a localized area in the brain, these seizures cause specific symptoms. In some patients, partial seizure activity may spread to the entire brain, causing a generalized seizure. Partial seizures include simple partial (jacksonian motor-type and sensory-type), complex partial (psychomotor or temporal lobe), and secondarily generalized partial seizures.
Simple partial (jacksonian motor-type) seizure
This type begins as a localized motor seizure, which is characterized by a spread of abnormal activity to adjacent areas of the brain. Typically, the patient experiences a stiffening or jerking in one extremity, accompanied by a tingling sensation in the same area. For example, the seizure may start in the thumb and spread to the entire hand and arm. The patient seldom loses consciousness, although the seizure may secondarily progress to a generalized tonic-clonic seizure.
Simple partial (sensory-type) seizure
Perception is distorted in this type of seizure. Symptoms can include hallucinations, flashing lights, tingling sensations, a foul odor, vertigo, or déjà vu.
Complex partial (psychomotor or temporal lobe) seizure
Symptoms of this seizure type are variable but usually include purposeless behavior. The patient may experience an aura and exhibit overt signs, including a glassy stare, picking at his clothes, aimless wandering, lip smacking or chewing motions, and unintelligible speech. A seizure may last for a few seconds or as long as 20 minutes. Afterward, mental confusion may last for several minutes; as a result, an observer may mistakenly suspect psychosis or intoxication with alcohol or drugs. The patient has no memory of his actions during the seizure.
Secondarily generalized partial seizure
This type of seizure can be either simple or complex and can progress to generalized seizures. An aura may precede the progression. Loss of consciousness occurs immediately or within 1 to 2 minutes of the start of the progression.
Generalized seizures
As the term suggests, these seizures cause a generalized electrical abnormality within the brain. They include several distinct types.
Absence seizure
This type occurs most often in children, although it may affect adults as well. It usually begins with a brief change in level of consciousness, indicated by blinking or rolling of the eyes, a blank stare, and slight mouth movements. The patient retains his posture and continues preseizure activity without difficulty. Typically, a seizure lasts from 1 to 10 seconds. The impairment is so brief that the patient is sometimes unaware of it. If not properly treated, these seizures can recur as often as 100 times a day. An absence seizure may progress to a generalized tonic-clonic seizure.
Myoclonic seizure
Also called bilateral massive epileptic myoclonus, this seizure type is marked by brief, involuntary muscular jerks of the body or extremities, which may occur in a rhythmic manner, and a brief loss of consciousness.
Generalized tonic-clonic seizure
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