A seizure represents a temporary disruption of normal brain activity, manifesting as sudden, uncontrolled bursts of electrical signals within the brain. These events can lead to a range of symptoms, including changes in behavior, movements, sensations, and levels of consciousness. While some seizures are easily recognizable due to their dramatic physical manifestations, others may be subtle, presenting as brief staring spells or minor muscle twitching. The duration of most seizures typically ranges from 30 seconds to two minutes, though a seizure lasting longer than five minutes requires urgent medical attention.
How Seizures Begin in the Brain
The brain functions through a complex network of nerve cells, called neurons, which communicate by generating and transmitting electrical impulses. These impulses allow neurons to send messages throughout the brain and to the rest of the body, orchestrating every thought, feeling, and action. During a seizure, this orderly communication system is momentarily overwhelmed by a sudden, intense surge of abnormal electrical activity.
This uncontrolled firing of signals by groups of neurons disrupts the regular patterns of electrical pulses. The specific symptoms experienced during a seizure depend on which areas of the brain are affected by this abnormal electrical discharge. For instance, if the motor cortex is involved, involuntary movements may occur, while involvement of other regions could lead to altered awareness or unusual sensations.
Conditions That Lead to Seizures
Various underlying medical conditions and circumstances can contribute to the development of seizures by affecting the brain’s electrical stability. Structural changes in the brain, such as those resulting from head or brain injuries, can predispose individuals to seizures. Strokes, which deprive parts of the brain of oxygen, and brain tumors are also significant causes, especially in older adults.
Infections that inflame the brain or its surrounding membranes, like meningitis or encephalitis, can disrupt normal neuronal activity and lead to seizures. Genetic factors and developmental abnormalities in brain structure that occur before birth also play a role, making certain individuals more susceptible. Metabolic imbalances, such as blood sugar or electrolyte disturbances, can interfere with nerve cell function and trigger a seizure. Drug or alcohol withdrawal can similarly provoke seizures due to the brain’s altered chemical balance.
Factors That Can Provoke a Seizure
While underlying conditions create a susceptibility to seizures, certain factors can act as triggers, provoking an event in individuals already predisposed. Sleep deprivation can lower a person’s seizure threshold, making them more vulnerable. Stress can also contribute to a seizure by impacting brain chemistry.
Illness or fever can provoke seizures, known as febrile seizures. Exposure to flashing lights, known as photosensitivity, can trigger seizures. Certain medications, or missing doses of prescribed anti-seizure medication, can also increase the likelihood of a seizure. Hormonal changes can also influence seizure activity.
Understanding Seizures and Epilepsy
It is important to differentiate between experiencing a single seizure and having epilepsy. A seizure is an isolated event of abnormal electrical activity in the brain, and it can occur for various reasons, such as a high fever or a head injury. Not everyone who has a seizure will develop epilepsy.
Epilepsy is defined as a chronic neurological condition characterized by recurrent, unprovoked seizures, meaning seizures that occur without an identifiable, reversible cause. A diagnosis of epilepsy requires an individual to have experienced two or more unprovoked seizures at least 24 hours apart. While a single seizure might be a symptom of another medical problem, epilepsy indicates a predisposition to ongoing seizure activity.