First Glance

According to the clinical symptomatology (and the EEG abnormalities),seizures can be broadly divided into following categories:

• Generalised seizures
• Complex partial seizures
• Simple partial seizures

Generalised Seizures

Generalised seizures are of four main types:

• Generalised tonic clonic seizure - Grand mal
• Absences : Petit mal
• Myoclonic seizures
• Tonic and atonic seizures

The main difference in generalised and partial seizures is the extent of involvement of the brain by the electrical activity. In generalised seizures, the involvement is extensive, but is limited in partial seizures.

Grand mal attacks are the commonest in clinical practice. The patient may or may not get warning of the attack. The attack consists of rapid loss of consciousness often with a loud cry followed by sustained tonic muscular contraction leading to the rhythmic clonic jerks. Seizure lasts for 1-2 minutes and is accompanied by tongue bite, urination and postictal gradual recovery.

Petit mal attacks or absences are seen in school going children. Attacks are brief and consist of momentary staring or blinking with rapid return to normalcy. Many attacks may occur in a day.
As a result of these attacks, children often lose grades at school and are referred for this reason, rather than seizures.

Complex Partial Seizures

In complex partial seizures, the patient is not entirely unconscious but loses consciousness, awareness and contact with the surroundings. In this state, the affected individual can perform seemingly complicated tasks and not remember them. Repetitive movements (automatism) or continuing to do the task that the person was doing before attack came (perseveration) are
common. These attacks may be difficult to clinically diagnose.

Simple Partial Seizures

In simple partial seizures, the area of neuronal hyperexcitability is small and hence consciousness is not affected. Partial seizures may progress to generalised seizures - the secondary generalisation. The secondary generalisation may at times be so fast that the initial partial nature is missed.

From the etiological point of view, seizures are either idiopathic (or primary) at macroscopic levels or symptomatic (or secondary) in whom the presumptive cause can be identified. Overall, about two thirds of epilepsies are idiopathic and the remaining one third are symptomatic. Generalised seizures are more likely to be idiopathic and partial seizures are more often due to a specific cause.

Table I lists some common causes of seizures in adults and children.