What causes a first-time seizure?

A seizure is a burst of abnormal electrical activity in the brain. Triggers can include fever or infection, low blood sugar, changes in salts, alcohol or drug withdrawal, medication effects, head injury, or a previous stroke. Some seizures arise from a structural change in the brain.

In oncology, a brain tumour or cancer that has spread to the brain can irritate or compress brain tissue and cause a seizure. Glioma and glioblastoma are tumour types that can involve the brain. A seizure by itself cannot identify which cause is present.

A first seizure needs medical assessment even if the person seems well afterward. Clinicians may ask what happened before, during, and after the event, review medicines and medical history, and arrange blood tests, brain imaging, or an electrical brain test.

During another event, move nearby hazards away, cushion the head, turn the person onto their side when possible, and do not put anything in the mouth or restrain them. Note the duration and recovery pattern for the medical team.

Call emergency services for a seizure lasting several minutes, repeated seizures without recovery, breathing difficulty, serious injury, pregnancy, diabetes, or a seizure in water. Urgent assessment is also needed for a first event, new weakness, confusion that persists, severe headache, fever with a stiff neck, or a known cancer history.

Could a medicine, infection, blood-sugar change, or electrolyte problem have triggered this event? Do I need brain imaging or an electrical brain test? What driving, work, bathing, or swimming precautions apply? Which symptoms should make me call emergency services?