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 in

Classifying 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