A childhood seizure is a sudden, uncontrolled burst of electrical activity within the brain, occurring when the nerve cells (neurons) become abnormally synchronized and overactive, temporarily interrupting normal function. While a seizure can involve physical convulsions or a brief loss of awareness, experiencing a single seizure does not automatically mean a child has epilepsy. Epilepsy is a neurological condition defined by the predisposition to have recurrent, unprovoked seizures, meaning those not triggered by an acute medical event. The causes of seizures in children are varied, ranging from temporary disruptions of the body’s chemistry to permanent changes in brain structure or genetics.
Transient Causes: Febrile Seizures
The most common cause of seizures in young children is a rapid rise in body temperature, which leads to a febrile seizure. These episodes typically affect children between the ages of six months and five years, with the highest risk occurring in the first three years of life. A febrile seizure is defined as one that happens with a fever of 100.4°F (38°C) or greater, and is not caused by an underlying central nervous system infection.
Genetic predisposition and the effect of fever on the developing nervous system are thought to contribute to these seizures. Simple febrile seizures usually last less than 15 minutes, affect the whole body, and do not recur within a 24-hour period. The long-term outlook for children with simple febrile seizures is excellent, with no negative effects on intellect or academic progress.
The majority of children who experience them do not develop epilepsy later in life. However, complex febrile seizures, which are longer or occur more than once in a day, may slightly increase the risk of a future seizure disorder. Health providers do not typically recommend anti-epileptic medications for simple febrile seizures due to the low risk of long-term issues.
Acute Functional Disturbances
Seizures can also be provoked by acute disturbances that disrupt the brain’s immediate internal environment, often referred to as acute symptomatic seizures. The brain relies on a stable chemical and metabolic balance, and deviations can trigger abnormal electrical firing. Conditions that cause low blood sugar (hypoglycemia) can lead to seizures because glucose is the main energy source for brain cells.
Electrolyte imbalances, such as low sodium (hyponatremia) or low calcium (hypocalcemia), also interfere with the normal signaling pathways between neurons. Correcting the underlying metabolic disturbance, such as administering glucose for low blood sugar, often stops the seizure activity and resolves the immediate risk. These acute seizures are not considered epilepsy because they are directly provoked by an identifiable, transient medical issue.
Acute infections of the central nervous system, including meningitis or encephalitis, can cause seizures by directly inflaming or damaging brain tissue. The resulting irritation and pressure within the skull can provoke seizure activity. Treating the infection is the primary method of addressing the seizure risk.
Inborn errors of metabolism, rare genetic disorders affecting how the body processes energy or detoxifies waste, can also cause seizures due to the accumulation of toxic compounds. For instance, disorders of the urea cycle can lead to the buildup of neurotoxic ammonia, which then causes seizures and brain swelling.
Structural and Developmental Etiologies
A group of childhood seizures arises from physical abnormalities within the brain tissue, categorized as structural etiologies. These structural issues act as fixed points of abnormal electrical activity, often leading to chronic, difficult-to-control seizures. One of the most common causes of this type of seizure is focal cortical dysplasia (FCD), a congenital condition where the outer layer of the brain, the cerebral cortex, fails to form correctly during fetal development.
In FCD, neurons do not migrate to their proper six-layered destinations, creating a patch of disorganized cells that are prone to generating seizures. This is not a degenerative condition but a static “wiring” problem present from birth, and it is a leading cause of drug-resistant epilepsy in children. Other developmental issues include low-grade brain tumors, such as gangliogliomas, which are slow-growing lesions that can disrupt the surrounding brain tissue and trigger seizures.
Acquired structural injuries can also cause seizures by creating scar tissue, which is highly excitable and can act as a seizure focus. Severe traumatic brain injury (TBI) from accidents is estimated to cause epilepsy in a percentage of cases, depending on the severity of the initial trauma. Vascular events, such as a stroke in a child, can lead to localized damage and the subsequent development of epilepsy, with the risk being highest following severe strokes involving the cortex.
Genetic and Unknown Epilepsy Syndromes
Many chronic epilepsy conditions in children have a strong genetic basis, either inherited or resulting from spontaneous mutations. Genetic causes are those where a person’s genes directly influence seizure development, often by affecting the function of ion channels that regulate nerve cell communication. For example, Dravet syndrome, a severe form of epilepsy, is frequently caused by a mutation in the SCN1A gene, which codes for a sodium channel protein.
Genetic epilepsy syndromes are diverse, ranging from childhood absence epilepsy to more severe syndromes like Lennox-Gastaut syndrome, which can involve multiple seizure types and developmental delays. Not all genetic epilepsies are inherited from a parent; many arise from a new, random genetic mutation in the affected child. Identifying the specific gene mutation can be challenging, and some cases involve a complex interaction of multiple genes and environmental factors.
Despite extensive testing, the cause of epilepsy remains unidentified in a number of children, a condition often termed “epilepsy of unknown etiology” or “idiopathic.” This designation is used when current investigative methods fail to pinpoint a clear reason for the seizures, meaning no structural abnormality or acute trigger can be identified. The underlying cause is presumed to be genetic or a combination of factors that science has yet to fully map. Up to half of all epilepsy cases fall into this category, highlighting the complexity of the brain’s electrical systems.