Pediatric emergency medicine trisk 357

consciousness is impaired, can lead to hypoxia, hypercarbia, and respiratory
acidosis. Patients with impaired consciousness may be unable to protect their
airway and are at risk for aspiration. Prolonged skeletal muscle activity can lead
to lactic acidosis, rhabdomyolysis, hyperkalemia, hyperthermia, and
hypoglycemia.

ETIOLOGY
It is important to remember that a seizure does not constitute a diagnosis but is
merely a symptom of an underlying pathologic process that requires a thorough
investigation ( Table 72.1 ). Often, no underlying condition is identified, and the
diagnosis of idiopathic epilepsy is made. However, it is important not to exclude
potentially treatable causes prematurely. For instance, seizures that result from
metabolic derangements (e.g., hyponatremia, hypoglycemia) are often refractory
to anticonvulsant therapy until the abnormality is corrected. Therefore, rapid
point-of-care testing for glucose and sodium are recommended for pediatric
status. Furthermore, every effort should be made to rule out a potentially lifethreatening cause of seizures (e.g., intracranial injury or hemorrhage, meningitis,
ingestions) before a less serious diagnosis is accepted.


TABLE 72.1
ETIOLOGY OF SEIZURES a


Infectious
Brain abscess
Encephalitis
Febrile (nonspecific)
Meningitis
Parasites (central nervous system)
Syphilis
Idiopathic

Subtherapeutic anticonvulsant level
Withdrawal
Alcohol
Hypnotics
Toxicologic
Anticonvulsant
Camphor
Carbon monoxide
Cocaine
Heavy metals (lead)
Hypoglycemic agents
Isoniazid
Lithium
Methylxanthines
Pesticides (organophosphates)
Phencyclidine
Sympathomimetics
Tricyclic antidepressants
Topical anesthetics
Degenerative cerebral disease
Hypoxic ischemic injury
Hepatic failure
Metabolic
Hyperosmolarity
Hypocalcemia
Hypoglycemia
Hypomagnesemia


Hyponatremia

Hypoxia
Inborn errors of metabolism
Pyridoxine
deficiency
Uremia
Vascular
Cerebrovascular accident
Hypertensive encephalopathy
Oncologic
Primary brain tumor
Metastatic disease
Endocrine
Addison disease
Hyper/hypothyroidism
Obstetric
Eclampsia
Traumatic
Cerebral contusion
Diffuse axonal injury
Intracranial hemorrhage
Congenital anomalies
a Bold

type denotes most common causes. Given their nature, virtually all these etiologies are potentially
life-threatening, except perhaps febrile seizures. Febrile seizures and breakthrough seizures of patients with
known epilepsy (whether compliant with their medication or not) represent the majority of seizure episodes
encountered in an emergency department setting.

DIFFERENTIAL DIAGNOSIS
There are many different types of events that mimic seizure activity.

Syncope, or the transient loss of consciousness that results from inadequate
cerebral perfusion or substrate delivery, is the most common alternative diagnosis
given to patients who present for the evaluation of a seizure episode (see Chapter
76 Syncope ). Further complicating matters is the fact that a small percentage of
patients with syncope exhibit some sort of convulsive movement. Although
vasovagal episodes or orthostatic hypotension is the most common cause for
syncope, it is important to evaluate these patients for potential underlying cardiac
disease.