Seizures (or convulsions) are temporary alterations in brain functions due to abnormal electrical activity of a group of brain cells that present with apparent clinical symptoms and findings. So, an isolated abnormal electrical activity recorded by an electroencephalography examination without a clinical presentation is not called a seizure. Seizure is usually a sudden and involuntary contraction of a group of muscles. However, a seizure can also be as subtle as marching numbness of a part of body, a brief loss of memory, sparkling of flashes, sniffing an unpleasant odor, a strange epigastric sensation or a sensation of fear. Therefore, it is traditional to classify the seizures as motor, sensory, autonomic, emotional and cognitive.
Seizure types are:
- petit mal seizure (very brief loss of consciousness)
- partial (focal) seizure (usually a motor or sensory seizure that is restricted to one side of the body)
- partial complex seizure (characterized by brief loss of consciousness, behavioral, emotional symptoms, loss of memory and automatisms; temporal lobe and frontal lobe seizures are often in this category)
- generalized tonic-clonic seizure (grand mal; motor seizure of both sides of the body)
It is still disputable whether a febrile seizure has to be regarded as an epileptic disorder or not. In general, a patient with two or more episodes of seizures is accepted to have the disease of epilepsy. So, seizure is the name of a symptom and epilepsy is the name of a disease.
Major causes of seizures are head trauma, infection, tumor and metabolic alterations (e.g. low or high blood glucose levels). Many seizures are due to unknown reasons.