Tintinalli's Emergency Medicine - Just the Facts, 3ed.

78. SEIZURES AND STATUS EPILEPTICUS IN CHILDREN

James C. O’Neill

images Unusual movements and changes in behavior in children often lead to an ED visit. Although seizures account for many of these events, as many as 30% or more of paroxysmal events may be misdiagnosed as seizures.

images Most seizure activity stops before the child is seen in an ED. Therefore, history is key to making the correct diagnosis.

images There are many different causes of pediatric seizures. The goal is to identify and treat the underlying cause. Some seizures require emergency management and extensive evaluation (eg, neonatal seizures); others are very common and benign and need little evaluation (eg, febrile seizures).

EPIDEMIOLOGY

images Approximately 1% to 2% of the U.S. population has epilepsy, although the lifetime likelihood of at least one seizure is nearly 9%.

images Simple febrile seizures constitute a separate category, with an incidence of 3% to 5% in children.

PATHOPHYSIOLOGY

images Seizures represent synchronous firing of neurons in the brain leading to paroxysmal involuntary motor activity and/or changes in behavior or consciousness. The release of glutamate from a firing neuron activates N-methyl-d-aspartic acid receptors that subsequently initiate and propagate seizure activity.

images Seizures are inhibited by γ-aminobutyric acid (GABA), and failure of this inhibition facilitates seizure spread.

CLINICAL FEATURES

images Seizures can be generalized (involving both hemispheres with alteration in consciousness) or partial (involving a limited area of the brain), although partial seizures can become generalized and vice versa.

images A convulsive generalized seizure involves both hemispheres of the brain and rhythmic motor stiffening and/or shaking affects both sides of the body.

images A nonconvulsive generalized seizure also involves both hemispheres of the brain but manifests no motor activity—seizure activity is recognizable only on EEG and as altered level of consciousness.

images During both convulsive and nonconvulsive generalized seizures, the patient loses consciousness and a postictal period follows.

images An absence seizure manifests as a brief episode of staring without a postictal state.

images In atonic seizures a patient suddenly loses muscle tone and drops to the ground.

images Myoclonic seizures occur when a patient has a sudden, brief, total body jerking movement.

images Partial seizures are focal, involving only part of the brain, with manifestations correlating with the affected area. In a simple partial seizure, the patient is awake.

images Complex partial seizures are focal but involve loss of consciousness.

images Status epilepticus is a “prolonged seizure” or recurrent seizures lasting >5 minutes without the patient’s regaining consciousness. Rapid cessation of status epilepticus is important to prevent irreversible neuronal damage.

DIAGNOSIS AND DIFFERENTIAL

images The diagnosis of seizure disorder is based primarily on history and physical examination, with laboratory studies (other than a bedside glucose) obtained in a problem-focused manner.

images True seizures must be distinguished from mimics that include breath-holding spells, vasovagal events, hypoglycemia, acute life-threatening event (ALTE), benign sleep myoclonus, movement disorders, night terrors, Sandifer syndrome (gastroesophageal reflux disease), and nonepileptic paroxysmal event (pseu-doseizures).

images Unlike adults, routine laboratory testing and neu-roimaging are not recommended for most pediatric seizures including simple febrile seizures, complex febrile seizures with return to baseline, or new-onset afebrile seizures. ED investigations are helpful in some specific circumstances, however.

images Serum drug level determinations are useful for phenobarbital, phenytoin, valproic acid, and carbamazepine in patients with known epilepsy and breakthrough seizures or status epilepticus, whereas levels of the newer agents may not be immediately available or useful in guiding therapy.

images Serum chemistry studies (ie, electrolytes, magnesium, calcium, creatinine, and blood urea nitrogen levels) are usually not indicated except in neonatal seizures, infantile spasms, and status epilepticus, or suspected metabolic or gastrointestinal disorders.

images Serum ammonia, TORCH (toxoplasmosis, rubella, cytomegalovirus, and herpes) titers, and urine and serum amino acid screening may be useful in evaluating neonatal seizures.

images Blood gas analysis is indicated in neonatal seizures and status epilepticus.

images ECG is useful to assess the PR and QT intervals and the possibility of cardiac dysrhythmia as the precipitant of seizure.

images Toxicology screening may be useful in adolescents suspected of recreational drug use (eg, cocaine).

images Magnetic resonance imaging is the preferred neuroim-aging procedure for most cases of new-onset seizures, but can usually be performed as an outpatient. Non-contrast computed tomography is indicated in cases of suspected head trauma, afebrile status epilepticus, and focal seizures or focal neurologic signs.

images Lumbar puncture should be performed in patients with neonatal seizure, infantile spasms, and febrile status epilepticus as well as patients with meningeal signs, or persistent alteration in consciousness.

EMERGENCY DEPARTMENT CARE AND DISPOSITION

STATUS EPILEPTICUS

images Most seizures stop within 5 minutes and do not require medical treatment. Status epilepticus (seizure activity lasting for >5 minutes or multiple seizures over a period of >5 minutes) is more responsive to medications when treated early, and medical treatment becomes less effective with time.

images Pediatric Advanced Life Support (PALS)® guidelines should be implemented in patients who present in status epilepticus. IV access is essential, but other routes of medication delivery can be used (IO, IM, intranasal, PR, or buccal) so as not to delay treatment.

images Benzodiazepines are first-line therapy in the seizing patient and are summarized in Table 78-1.

images Figure 78-1 outlines the initial and subsequent management of refractory status epilepticus including second-line pharmacologic options for patients unresponsive to benzodiazepines.

images Rapid bedside testing for electrolytes and glucose levels (glucose, sodium, and calcium) is recommended in status epilepticus when available. Order a complete blood count (CBC), full chemistry panel, hepatic and renal studies, and anticonvulsant levels, if appropriate, when an IV or IO is placed. Other studies may be needed depending upon the suspected underlying cause of seizures. Consider CNS infection and lumbar puncture in the child with febrile status epilepticus. The decision to intubate is clinical, the most common causes being apnea and hypoxia.

images The use of a paralytic with intubation will obscure the ability to assess ongoing seizure activity, and continuous EEG monitoring should be arranged for intubated patients with status epilepticus.

images All patients with status epilepticus require hospi-talization and those with persistent seizure activity require admission to intensive care.

TABLE 78-1 Benzodiazepines for Initial Treatment of Status Epilepticus

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FIG. 78-1. Treatment of status epilepticus. IN = intranasal; PE = phenytoin sodium equivalents.

FEBRILE SEIZURES

images Simple febrile seizures are defined as generalized tonic-clonic, lasting <15 minutes, with a fever >38°C (>100.4°F) in a child 6 months to 5 years of age that occurs only once in a 24-hour period.

images Identification and treatment of the cause of fever is the primary goal of therapy for febrile seizures, and specific laboratory and radiologic evaluation is otherwise not needed.

images Complex febrile seizures are defined as seizures with fever that last >15 minutes, recur within a 24-hour period, are focal, or occur in children <6 months or >5 years of age without signs of serious infection. Recent guidelines recommend against routine lumbar puncture or neuroimaging in patients who return to baseline and have a normal examination in the ED. All patients with persistent focal deficits or meningeal signs, however, require further ED evaluation and testing.

images Anticonvulsant therapy is not recommended for simple febrile seizures. Although antipyretics are indicated in children with fever, there is no evidence that antipyretics can prevent subsequent febrile seizures.

NEONATAL SEIZURES

images Neonates (<1 month of age) do not have a fully developed neurologic system. Seizures occurring in this age group can be subtle, are more likely to be focal, and often carry a poor prognosis.

images Regardless of fever history, neonates with seizures need a full evaluation for sepsis (blood, urine, and CSF) and IV antibiotics. Neonatal seizures may be caused by herpes simplex encephalitis regardless of the maternal history. Blood and CSF testing for herpes simplex virus and treatment with acyclovir are indicated.

images A toxicologic evaluation may provide the physician with evidence of withdrawal or overdose of abused substances. Neonates with seizures are more likely to have electrolyte abnormalities than older children. Head CT evaluates for concerns of nonaccidental trauma, intracranial hemorrhage, infarction, or mass.

images If inborn errors of metabolism are suspected, levels of lactate, ammonia, and serum amino and urine organic acids should be obtained.

HYPONATREMIA

images Excessive water drinking can lead to hyponatremia (<135 mEq/L). Hyponatremia is most commonly seen in infants <6 months of age and sometimes in athletes. Babies who drink several bottles of water a day or who drink dilute infant formula are at risk for hyponatremia. Athletes can also suffer from water intoxication.

images Hyponatremia can cause seizures, especially if the sodium level is <120 mEq/L. The goal of therapy is to correct the level to >120 mEq/L quickly to treat or prevent further seizure activity, and then correct the sodium to normal levels over the next 24 hours.

images If a patient is actively experiencing seizure, the treatment of choice is 3% NaCl. An infusion of 20 mL/kg of 0.9% NaCl should be started immediately for patients in status epilepticus if delivery of 3% NaCl is delayed.

HYPOGLYCEMIA

images Hypoglycemia is defined as a glucose level of <50 milligrams/dL regardless of whether symptoms exist. Seizures can occur with hypoglycemia, so glucose levels should be measured in all patients presenting with seizures.

images If hypoglycemia is present, patients should be treated with a rapid infusion of 4 mL/kg of 10% dextrose in water (2 mL/kg D25 in older children).

HYPOCALCEMIA

images Hypocalcemia is caused by abnormal calcium absorption, excretion, or distribution and can also cause seizures. Hypocalcemia is more common in neonates and young infants and may be associated with congenital anomalies such as DiGeorge syndrome.

images Treat with 10% calcium gluconate (0.3 mL/kg administered slowly over 5–10 minutes).

SEIZURES IN CHILDREN WITH EPILEPSY

images Epilepsy is defined as two or more unprovoked seizures (eg, no fever or trauma). Diagnosing the type of seizure and determining the best treatment can be complex.

images Parents, old records, and pediatric neurologists can be very helpful in identifying past causes of seizures, successful treatment, and other issues that can help direct care.

images When children with epilepsy who are taking anticonvulsant medications are brought to the ED with seizure, drug levels should be checked if the corresponding assays are available.

images Children with epilepsy may have a lower seizure threshold with febrile illness, even with therapeutic anticonvulsant levels.

SEIZURES IN CHILDREN WITH A VENTRICULOPERITONEAL SHUNT

images Many children with ventriculoperitoneal (VP) shunts also have a medical history of seizures. Considerations include underlying epilepsy, shunt malfunction, and CNS infection.

images The standard approach to the evaluation for a shunt malfunction consists of a radiographic VP shunt series and a head CT or “quick brain MRI” (fast spin echo T2-weighted images performed rapidly typically without sedation) to evaluate for increased ventricular size. If a CNS infection is a concern, a pediatric neurosurgeon should be consulted to consider tapping the shunt for CSF analysis.

SEIZURES IN CHILDREN WITH HEAD TRAUMA

images Children with acute trauma who have seizures may have experienced intracranial injury.

images Those with obvious significant trauma should undergo imaging. “Impact seizures” (seizures that occur within minutes of head trauma) are not associated with severe head injuries. However, seizures that occur in a delayed fashion following injury are more likely to be indicative of severe intracranial injuries.

FIRST-TIME AFEBRILE SEIZURES

images The overall risk of recurrence after a single afebrile seizure is roughly 40%.

images Most neurologists do not recommend daily administration of anticonvulsant medications after a first seizure.

images Only patients with prolonged or repetitive witnessed seizures, especially with concomitant neurologic deficit, are started on antiepileptic drugs. The choice of antiepileptic drug is based on seizure type, side-effect profile, and ease of administration, and should usually be discussed with the primary physician or neurologist.


For further reading in Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7th ed., see Chapter 129, “Seizures and Status Epilepticus in Children,” by Maija Holsti.