Why is Classification Important?
The correct classification of each person's epilepsy by seizure type and epilepsy syndrome is important for proper treatment. Identifying the type of seizure has the most immediate influence on therapy. If the seizure is classified incorrectly, the seizure medicine that the doctor prescribes not only may not help but actually may make the seizures worse. For example, a man who had two generalized tonic-clonic seizures while he was sleeping was thought to have partial seizures and was given Tegretol (carbamazepine). The man continued to have an occasional tonic-clonic seizure during sleep even though he took his medicine faithfully. Several months later, he had an EEG after a period of sleep deprivation. This test showed a pattern of generalized spike-and-wave discharges, which is a sign of a generalized seizure. His medicine was changed to Depakote (valproate), which is the drug of choice to treat generalized seizures. The new seizure medicine completely stopped his seizures.
Besides classifying seizures into types, doctors also try to classify a patient's seizures into an epilepsy syndrome. Classifying seizures into syndromes provides much more information. By considering factors such as the age at which the seizures began, the type or types of seizures that are occurring, how long the patient has been experiencing seizures and when they occur, the results of EEG and MRI studies, and so on, the doctor may be able to diagnose a particular syndrome. Having this information helps the doctor predict the probable course of the seizure disorder and the best options for medication or surgical treatment.
For instance, one well-known epilepsy syndrome that affects children is called benign rolandic epilepsy (BRE). Children with BRE usually achieve good seizure control with seizure medicines, unlike children with another syndrome called symptomatic frontal lobe seizures. The seizures of children with BRE usually stop on their own by age 16, so doctors and parents may decide not to give seizure medicines to children with BRE if their seizures are mild and infrequent. On the other hand, even though the individual seizures of children with symptomatic frontal lobe seizures may look like the seizures of children with BRE, they cannot be expected to stop on their own. Children with symptomatic frontal lobe seizures therefore will need more intensive treatment with seizure medicines and additional tests.
Another example of a well-known syndrome is juvenile myoclonic epilepsy (JME). Patients with JME begin having seizures during adolescence. The seizures occur mostly in the morning, and are either tonic-clonic, myoclonic, or absence seizures. The presence of myoclonic jerks in the morning and the generalized pattern on the EEG helps determine the diagnosis of the syndrome. Young people with JME can be helped to prevent seizures by being counseled to avoid sleep deprivation and alcohol use, both of which may trigger their seizures. Selecting the right seizure medicine, usually Depakote, is also important for control of seizures in patients with JME. If the doctor fails to recognize the syndrome, another medicine may be prescribed that may make the seizures worse instead of better.
The classification system is also used to identify which patients are most likely to benefit from surgery to treat their epilepsy, as well as the type of surgery that is needed. For example, a person with mesial temporal sclerosis may be given a 90% chance for cure, but one with frontal lobe epilepsy involving the motor area may have only a 60% chance (or less) of being free of seizures after surgery.
The system for classification of seizures and syndromes also works well for teaching both patients and health care professionals about epilepsy. It provides a framework for discussion about the different types of seizures and epilepsy syndromes. This framework makes it much easier for doctors and researchers to share information with each other and with other professionals. Tests of seizure medicines involving patients, as well as other aspects of research on epilepsy, are designed and carried out using the agreed-upon classification system.
Recent technological advances in diagnostic techniques and the rapid developments in our knowledge of genetics have greatly improved our insight into epilepsy seizures and syndromes. The current classification system is certain to be revised soon to reflect our growing understanding of epilepsy.