Epilepsy is a common chronic neurological disorder characterized byrecurrent unprovoked seizures. These seizures are transient signs and/or symptomsof abnormal, excessive or synchronous neuronal activity in the brain. Epilepsyis more likely to occur in young children or people over the age of 65 years;however it can occur at any time. Not all epilepsy syndromes are lifelong –some forms are confined to particular stages of childhood. Epilepsy should notbe understood as a single disorder, but rather as syndromic with vastlydivergent symptoms but all involving episodic abnormal electrical activity inthe brain.
Epilepsies are classified in five ways:
- By their first cause (or etiology).
- By the observable manifestations of the seizures, known as semiology.
- By the location in the brain where the seizures originate.
- As a part of discrete, identifiable medical syndromes.
- By the event that triggers the seizures, as in primary reading epilepsy or musicogenic epilepsy.
Seizure types are organized firstly according to whether the source of theseizure within the brain is localized (partial or focal onset seizures) or distributed (generalized seizures). Partialseizures are further divided on the extent to which consciousness is affected.If it is unaffected, then it is a simple partial seizure; otherwise itis a complex partial (psychomotor)seizure. A partial seizure may spread within the brain - a process known as secondary generalization. Generalizedseizures are divided according to the effect on the body but all involve lossof consciousness. These include absence(petit mal), myoclonic,clonic, tonic, tonic-clonic (grand mal) and atonicseizures.
Children may exhibit behaviors that are easily mistaken for epilepticseizures but are not caused by epilepsy. These include:
- Inattentive staring
- Benign shudders (among children younger than age 2, usually when they are tired or excited)
- Self-gratification behaviors (nodding, rocking, head banging)
- Conversion disorder (flailing and jerking of the head, often in response to severe personal stress such as physical abuse)
Conversion disorder can be distinguished from epilepsy because the episodesnever occur during sleep and do not involve incontinence or self-injury.