convulsion

A convulsion is a sudden, involuntary contraction of muscles caused by abnormal electrical activity in the brain. When a convulsion is part of a generalized, all‑over disturbance, it is commonly described as a seizure. The term convulsion is sometimes used specifically for the visible, clonic or tonic movements, whereas some seizures may occur without prominent convulsions. Convulsions can occur in many neurological and systemic conditions and are not by themselves a diagnosis.

Common causes include febrile illness in children, epilepsy, head injury, stroke, brain infections, metabolic disturbances (such as low blood sugar or electrolyte imbalances), toxins, withdrawal from alcohol or drugs, and certain genetic or developmental conditions. Febrile convulsions are a distinct, typically benign phenomenon seen in young children during fever.

Clinical features vary. Generalized tonic-clonic convulsions involve stiffening (tonic) followed by rhythmic jerking (clonic) with loss of consciousness, and may be accompanied by facial grimacing, tongue biting, or incontinence. Some events are focal or involve myoclonic jerks. Afterward, a period of confusion or sleepiness (the postictal state) is common.

Diagnosis relies on history and physical examination. EEG and brain imaging may be used if there are abnormal findings, new onset in adulthood, prolonged events, or focal neurological signs. Blood tests and toxin screens may help identify underlying causes.

First aid focuses on safety: protect the person from injury, do not restrain movements or place objects in the mouth, and time the convulsion. If it lasts longer than five minutes or repeats without recovery, seek emergency medical care. In a hospital setting, treatment targets the underlying cause and may include benzodiazepines for ongoing convulsions and, if needed, longer‑term anticonvulsant therapy.

Prognosis depends on cause and context. Simple febrile convulsions are usually benign; prolonged or recurrent convulsions warrant evaluation for epilepsy or other underlying conditions. Complications can include injury or aspiration during the event.