Seizure disorder
Description
Neurologic condition characterized by recurrent seizures
No effect on intelligence
Usually occurs in patients of both sexes younger than age 20
First seizure usually experienced during childhood or after age 50
Good seizure control in about 80% of patients with strict adherence to prescribed treatment
Also known as epilepsy
Pathophysiology
Seizures occur as paroxysmal events involving abnormal electrical discharges of neurons in the brain and cell membrane potential. (See Classifying seizures, pages 204 and 205.)
On stimulation, the neuron fires, the discharge spreads to surrounding cells, and stimulation continues to one side or both sides of the brain, resulting in seizure activity.
Causes
Idiopathic (50% cases)
Nonidiopathic
Anoxia
Apparent familial incidence in some seizure disorders
Birth trauma
Brain tumors or other space-occupying lesions
Genetic abnormalities (tuberous sclerosis and phenylketonuria)
Ingestion of toxins, such as mercury, lead, or carbon monoxide
Meningitis, encephalitis, or brain abscess
Metabolic abnormalities (hypoglycemia, pyridoxine deficiency, hypoparathyroidism)
Perinatal infection
Perinatal injuries
Traumatic injury
Focus inClassifying seizures
Seizures can take various forms, depending on their origin and whether they’re localized to one area of the brain, as occurs in partial seizures, or occur in both hemispheres, as happens in generalized seizures. This chart describes each type of seizure and lists common signs and symptoms.
| Type | Description | Signs and symptoms | ||
| Partial | ||||
| Simple partial | Symptoms confined to one hemisphere | Possibly having motor (change in posture), sensory (hallucinations), or autonomic (flushing, tachycardia) symptoms; no loss of consciousness | ||
| Complex partial | Beginning in one focal area but spreading to both hemispheres (more common in adults) | Loss of consciousness; aura of visual disturbances; postictal symptoms | ||
| Generalized | ||||
| Absence (petit mal) | Sudden onset; lasting 5 to 10 seconds; possibly having 100 daily; precipitated by stress, hyperventilation, hypoglycemia, fatigue; differentiated from daydreaming | Loss of responsiveness but continued ability to maintain posture control and not fall; twitching eyelids; lip smacking; no postictal symptoms | ||
| Myoclonic | Movement disorder (not a seizure); seen as child awakening or falling asleep; may be precipitated by touch or visual stimuli; focal or generalized; symmetrical or asymmetrical | No loss of consciousness; sudden, brief, shocklike involuntary contraction of one muscle group | ||
| Clonic | Opposing muscles contracting and relaxing alternately in rhythmic pattern; possibly occurring in one limb more than others | Mucus production | ||
| Tonic | Muscles maintained in continuous contracted state (rigid posture) | Variable loss of consciousness; pupils dilating; eyes rolling up; glottis closing; possible incontinence; possibly foaming at mouth | ||
| Tonic-clonic (grand mal, major motor) | Violent total body seizure | Aura; tonic first (20 to 40 seconds); clonic next; postictal symptoms | ||
| Atonic | Drop and fall attack; needing to wear protective helmet | Loss of posture tone | ||
| Akinetic | Sudden brief loss of muscle tone or posture | Temporary loss of consciousness | ||
| Febrile | Seizure threshold lowered by elevated temperature; only one seizure per fever; common in 4% of population under age 5; occurring when temperature is rapidly rising | Lasting less than 5 minutes; generalized, transient, and nonprogressive; doesn’t generally result in brain damage; EEG normal after 2 weeks | ||
| Status epilepticus | Prolonged or frequent repetition of seizures without interruption; resulting in anoxia and cardiac and respiratory arrest | Consciousness not regained between seizures; lasting more than 30 minutes |
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