Definition of the Complaint
Seizures, a common neurologic disorder that occurs in childhood, affect 4%-6% of all children. A seizure is defined as a transient, involuntary alteration of consciousness, behavior, motor activity, sensation, and/or autonomic function caused by an excessive rate and hypersynchrony of discharges from a group of cerebral neurons. Epilepsy is diagnosed after two or more unprovoked seizures. In other words, recurrent seizures only occurring with precipitating events such as illness, fever, or acute head trauma are typically not considered epilepsy, even though antiepileptic drugs may be used to treat the seizures acutely. The first step in formulating a differential diagnosis in a child who presents with ”seizures” is to characterize the type of event. Seizures are classified into generalized seizures (such as a tonic-clonic seizure affecting the entire body simultaneously) or focal seizures (arising from a specific area or areas of the cortex, with or without spread to the entire brain). The underlying cause is divided into three categories: genetic, structural/metabolic, and unknown cause. Genetic epilepsy is defined by seizures caused by a known or presumed genetic defect (e.g., SCN1A mutation). Structural/metabolic seizures are due to a lesion, such as stroke or tumor, but may also include infection. Tuberous sclerosis complex, while caused by a genetic mutation, is classified in this category because it is the structural changes in the brain, rather than being directly caused by the mutation itself, that result in epilepsy. The etiology of epilepsy that does not have a recognized genetic or structural/metabolic cause is classified as unknown.
This chapter will discuss possible causes of seizures. However, seizures should be differentiated from other childhood paroxysmal events that can mimic seizure activity. For example, prolonged syncope and clonic jerks occurring in the setting of a syncopal event may resemble a generalized tonic-clonic seizure. Syncope is the most common alternative diagnosis assigned to otherwise healthy patients who fall to the ground without warning. Atonic seizures or ”drop attacks” in which a child loses muscle tone are rare and typically occur in children with other seizure types as well (e.g., myoclonic and tonic seizures). Gastroesophageal reflux with opisthotonic posturing (Sandifer syndrome) frequently mimics seizures in infancy. Breath-holding spells, which occur in approximately 4% of infants, can resemble seizures and are also associated with cyanosis. A variety of movement disorders, such as benign myoclonus of infancy and Tourette syndrome, may also be mistaken for seizures. Additionally, seizure activity is often subtle, making seizures difficult to diagnose. For example, in the neonatal period seizures may present with horizontal eye movements, repetitive sucking, or pedaling and stepping motions that are difficult to distinguish from normal newborn infant activity. In older children, childhood absence epilepsy is characterized by a brief impairment of consciousness manifesting as a stare or behavioral arrest and is often mistaken for attention deficit disorder.
Complaint by Cause and Frequency
It is important to remember that a seizure does not ...