Seizures, generalized tonic-clonic
Like other types of seizures, generalized tonic-clonic seizures are caused by the paroxysmal, uncontrolled discharge of central nervous system (CNS) neurons, leading to neurologic dysfunction. Unlike most other types of seizures, however, this cerebral hyperactivity isn’t confined to the original focus or to a localized area but extends to the entire brain.
Generalized tonic-clonic seizures usually occur singly. The patient may be asleep or awake and active. (See What happens during a generalized tonic-clonic seizure.) Possible complications include respiratory arrest due to airway obstruction from secretions, status epilepticus (occurring in 5% to 8% of patients), head or spinal injuries and bruises, Todd’s paralysis and, rarely, cardiac arrest. Life-threatening status epilepticus is marked by prolonged seizure activity or by rapidly recurring seizures with no intervening periods of recovery. It’s most commonly triggered by abrupt discontinuation of anticonvulsant therapy.
Generalized seizures may be caused by a brain tumor, vascular disorder, head trauma, infection, metabolic defect, drug or alcohol withdrawal syndrome, exposure to toxins, or a genetic defect. Generalized seizures may also result from a focal seizure. With recurring seizures, or epilepsy, the cause may be unknown. (See How to respond to a seizure, page 600.)
History
If you didn’t witness the seizure, obtain a description from the patient’s companion. Ask when the seizure started and how long it lasted. Did the patient report any unusual sensations before the seizure began? Did the seizure start in one area of the body and spread, or did it affect the entire body right away? Did the patient fall on a hard surface? Did his eyes or head turn? Did he turn blue? Did he lose bladder control? Did he have any other seizures before recovering? Does he complain of headache and muscle soreness? Is he increasingly difficult to arouse when you check on him at 20-minute intervals?
Next, obtain a history. Has the patient ever had generalized or focal seizures before? If so, do they occur frequently? Do other family members also have them? Is the patient receiving drug therapy? Is he compliant? Also, ask about sleep deprivation and emotional or physical stress at the time the seizure occurred.
Physical assessment
If the patient may have sustained a head injury, observe him closely for loss of consciousness, unequal or nonreactive pupils, and focal neurologic signs. Examine his arms, legs, and face (including tongue) for injury, residual paralysis, or limb weakness. If you haven’t already done so, take the patient’s vital signs. Then complete your neurologic assessment.
Medical causes
Alcohol withdrawal syndrome
Sudden withdrawal from alcohol dependence may cause seizures 7 to 48 hours later as well as status epilepticus. The patient may also be restless and exhibit hallucinations, profuse diaphoresis, and tachycardia.
Arsenic poisoning
Besides generalized seizures, arsenic poisoning may cause a garlicky breath odor, increased salivation, and generalized pruritus. GI effects include diarrhea, nausea, vomiting, and severe abdominal pain. Related effects include diffuse hyperpigmentation; sharply defined edema of the eyelids, face, and ankles; paresthesia of the extremities; alopecia; irritated mucous membranes; weakness; muscle aches; and peripheral neuropathy.
Brain abscess
Generalized seizures may occur in the acute stage of abscess formation or after the abscess disappears. Depending on the size and location of the abscess, decreased level of consciousness (LOC) varies from drowsiness to deep stupor. Early signs and symptoms reflect increased intracranial pressure (ICP) and include constant headache, nausea, vomiting, and focal seizures. Typical later features include ocular disturbances, such as nystagmus, impaired vision, and unequal pupils. Other findings vary with the abscess site but may include aphasia, hemiparesis, abnormal behavior, and personality changes.
Brain tumor
Generalized seizures may occur, depending on the tumor’s location and type. Other findings include a slowly decreasing LOC, morning headache, dizziness, confusion, focal seizures, vision loss, motor and sensory disturbances, aphasia, and ataxia. Later findings include papilledema, vomiting, increased systolic blood pressure, widening pulse pressure, and (eventually) decorticate posture.
Cerebral aneurysm
Occasionally, generalized seizures may occur with an aneurysmal rupture. Premonitory signs and symptoms may last several days, but onset is typically abrupt with severe headache, nausea, vomiting, and decreased LOC. Depending on the site and amount of bleeding, related signs and symptoms vary but may include nuchal rigidity, irritability, hemiparesis, hemisensory defects, dysphagia, photophobia, diplopia, ptosis, and unilateral pupil dilation.
Eclampsia
Generalized seizures are a hallmark of eclampsia. Related findings include severe frontal headache, nausea and vomiting, vision disturbances, increased blood pressure, fever of up to 104° F (40° C), peripheral edema, and sudden weight gain. The patient may also exhibit oliguria, irritability, hyperactive deep tendon reflexes (DTRs), and decreased LOC.
Encephalitis
Seizures are an early sign of encephalitis, indicating a poor prognosis; they may also occur after recovery as a result of residual damage. Other findings include fever, headache, photophobia, nuchal rigidity, neck pain, vomiting, aphasia, ataxia, hemiparesis, nystagmus, irritability, cranial nerve palsies (causing facial weakness, ptosis, dysphagia), and myoclonic jerks.
Head trauma
In severe cases, generalized seizures may occur at the time of injury. (Months later, focal seizures may occur.) Severe head trauma may also cause a decreased LOC, leading to coma; soft-tissue injury of the face, head, or neck; clear or bloody drainage from the mouth, nose, or ears; facial edema; bony deformity of the face, head, or neck; Battle’s sign; and lack of response to oculocephalic and oculovestibular stimulation. Motor and sensory deficits may occur along with altered respirations. Examination may reveal signs of increasing ICP, such as decreased response to painful stimuli, nonreactive pupils, bradycardia, increased systolic pressure, and widening pulse pressure. If the patient is conscious, he may exhibit vision deficits, behavioral changes, and headache.
Hepatic encephalopathy
Generalized seizures may occur late in hepatic encephalopathy. Associated late-stage findings in the comatose patient include fetor hepaticus, asterixis, hyperactive DTRs, and a positive Babinski’s sign.
Hypertensive encephalopathy
Hypertensive encephalopathy, a life-threatening disorder, may cause seizures along with severely increased blood pressure, decreased LOC, intense headache, vomiting, transient blindness, paralysis, and (eventually) Cheyne-Stokes respirations.
Hypoglycemia
Generalized seizures usually occur with severe hypoglycemia, accompanied by blurred or double vision, motor weakness, hemiplegia, trembling, excessive diaphoresis, tachycardia, myoclonic twitching, and decreased LOC.
Hyponatremia
Seizures develop when serum sodium levels fall below 125 mEq/L, especially if the decrease is rapid. Hyponatremia also causes orthostatic hypotension, headache, muscle twitching and weakness, fatigue, oliguria or anuria, cold and clammy skin, decreased skin turgor, irritability, lethargy, confusion, and stupor or coma. Excessive thirst, tachycardia, nausea, vomiting, and abdominal cramps may also occur. Severe hyponatremia may cause cyanosis and vasomotor collapse, with a thready pulse.
Hypoparathyroidism
Worsening tetany causes generalized seizures. Chronic hypoparathyroidism produces neuromuscular irritability, Chvostek’s sign, dysphagia, tetany, and hyperactive DTRs.
Hypoxic encephalopathy
Besides generalized seizures, hypoxic encephalopathy may produce myoclonic jerks and coma. Later, if the patient has recovered, dementia, visual agnosia, choreoathetosis, and ataxia may occur.
Neurofibromatosis
Multiple brain lesions from neurofibromatosis cause focal and generalized seizures. Inspection reveals café-au-lait spots, multiple skin tumors, scoliosis, and kyphoscoliosis. Related findings include dizziness, ataxia, monocular blindness, and nystagmus.
Renal failure (chronic)
End-stage renal failure produces rapid onset of twitching, trembling, myoclonic jerks, and generalized seizures. Related signs and symptoms include anuria or oliguria, fatigue, malaise, irritability, decreased mental acuity, muscle cramps, peripheral neuropathies, anorexia, and constipation or diarrhea. Integumentary effects include skin color changes (yellow, brown, or bronze), pruritus, and uremic frost. Other effects include ammonia breath odor, nausea and vomiting, ecchymoses, petechiae, GI bleeding, mouth and gum ulcers, hypertension, and Kussmaul’s respirations.
Stroke
Seizures (focal more often than generalized) may occur within 6 months of an ischemic stroke. Associated signs and symptoms vary with the location and extent of brain damage. They include decreased LOC, contralateral hemiplegia, dysarthria, dysphagia, ataxia, unilateral sensory loss, apraxia, agnosia, and aphasia. The patient may also develop visual deficits, memory loss, poor judgment, personality changes, emotional lability, urine retention or urinary incontinence, constipation, headache, and vomiting.
Other causes
Barbiturate withdrawal
In chronically intoxicated patients, barbiturate withdrawal may produce generalized seizures 2 to 4 days after the last dose. Status epilepticus is possible.
Diagnostic tests
Contrast agents used in radiologic tests may cause generalized seizures.
Drugs
Toxic blood levels of some drugs, such as theophylline, lidocaine, meperidine, penicillins, and cimetidine, may cause generalized seizures. Phenothiazines, tricyclic antidepressants, amphetamines, isoniazid, and vincristine may cause seizures in patients with preexisting epilepsy.
Special considerations
Closely monitor the patient after the seizure for recurring seizure activity. Prepare him for a computed tomography scan or magnetic resonance imaging and EEG.
Pediatric pointers
Generalized seizures are common in children. In fact, between 75% and 90% of epileptic patients experience their first seizure before age 20. Many children between ages 3 months and 3 years experience generalized seizures associated with fever; some of these children later develop seizures without fever. Generalized seizures may also stem from inborn errors of metabolism, perinatal injury, brain infection, Reye’s syndrome, Sturge-Weber syndrome, arteriovenous malformation, lead poisoning, hypoglycemia, and idiopathic causes.
Patient counseling
Advise the patient’s family to observe and record his seizure activity to ensure proper treatment. Emphasize the importance of strict compliance with the drug regimen, and warn the patient about adverse reactions. Also, stress the importance of regular follow-up appointments for blood studies.
Pictures
Book Source Details
- Book Title: Signs & Symptoms: A 2-in-1 Reference for Nurses
- Author(s): Springhouse
- Year of Publication: 2007
- Copyright Details: Signs & Symptoms: A 2-in-1 Reference for Nurses, Copyright © 2007 Lippincott Williams & Wilkins.
Other Book Chapters Related to Convulsions
Read excerpts from these other book chapters related to Convulsions:
Medical Books Excerpts
- Seizures
- "A Pocket Manual of Differential Diagnosis" (1999)
- [ read ]
- Seizures
- "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
- [ read ]
- Seizures
- "The Diagnostic Approach to Symptoms and Signs in Pediatrics" (2006)
- [ read ]
Copyright Details: Signs & Symptoms: A 2-in-1 Reference for Nurses, Copyright © 2008 Williams & Wilkins.
More About Causes of Convulsions
» Next page: Seizures, simple partial (Signs & Symptoms: A 2-in-1 Reference for Nurses)
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