By Dr Ananya Mandal, MD
Seizures may be of two main types, partial and generalized. There are four components of a seizure.
Each of the four components are distinctly different and distinguished. Not all seizure types will have all these stages. Their presence or absence characterizes a type of seizure. The components are:
This phase usually starts a few hours or even days before the actual seizure. This is different from aura. Prodromal symptoms include insomnia, headache, irritability, ill-temper, increased agitation and depression.
Aura usually comes a few seconds to a few minutes before the actual seizure. It is the beginning of the seizure and is seen in partial seizures. The feelings of the aura are often vague and many patients are unable to describe their features. There may be feelings of extreme fear, sensations in the stomach, dreamlike experiences, unpleasant smells, hallucinations and other features of aura. Aura is usually well remembered and patient can recall and recount the incidents during this phase well enough.
This is the actual phase of the seizure. Generalised seizures occur if the abnormal electrical activity affects all or most of the brain. This affects most of the body. A tonic-clonic seizure is the most common type of generalised seizure. The whole body stiffens (tonic phase) and the person loses consciousness and falls. This is followed by a violent uncontrollable shaking (clonic phase).
Absence seizure is another type of generalised seizure. The person may lose consciousness or awareness. This is common in children.
Other types include a myoclonic seizure, a tonic seizure and an atonic seizure. In myoclonic seizures there are jerky movements of one or more limbs. In tonic seizure there is stiffening or contraction of muscles while in clonic seizures there is just uncontrolled movement of limbs. In atonic seizures the muscle tone of the body is lost and the patient falls.
Partial seizures are also called focal seizures. Here only one part of the brain is affected. There may be localised (focal) symptoms. These may be simple partial seizures or complex partial seizures.
Sometimes a partial seizure develops into a generalised seizure. This is called a secondary generalised seizure.
This is the phase following a seizure. This phase may be absent, brief or may last several hours or even days. After a generalized tonic-clonic seizure there is usually a deep sleep and waking up with headache. There may be severe tiredness, irritability, vomiting, confusion and balance problems.
Some patients may develop short term paralysis of a part of the body, known as Todd’s paresis. This may last for a few hours or days. If the dominant side of the brain (left side in a right handed individual for example) has been involved there may be abnormal and lost speech. Behaviour and emotions may be altered.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)