In a substantial number of cases, the cause of epilepsy remains unknown. Identified causes tend to vary with patient age. Inherited syndromes, congenital brain malformations, infection, and head trauma are leading causes in children. Head trauma is the most common known cause in young adults. Strokes, tumors, and head trauma become more frequent in middle age, with stroke becoming the most common cause in the elderly, along with Alzheimer disease and other degenerative conditions.

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Absence seizures are brief episodes of impaired consciousness with no aura or postictal confusion. They typically last less than 20 seconds and are accompanied by few or no automatisms. Myoclonic seizures consist of brief arrhythmic jerking motor movements that last less than 1 second and often cluster within a few minutes. If the seizures evolve into rhythmic jerking movements, they are classified as evolving into a clonic seizure. Clonic seizures consist of rhythmic jerking motor movements with or without impairment of consciousness; they can have a focal origin. Focal seizures are classified as simple or complex partial seizures. The typical generalized clonic seizures simultaneously involve the upper and lower extremities. Tonic seizures consist of sudden-onset tonic extension or flexion of the head, trunk, and/or extremities for several seconds. These seizures typically occur in relation to drowsiness, shortly after patients fall asleep, or just after they awaken. Atonic seizures are also called "drop attacks." These seizures typically occur in people with clinically significant neurologic abnormalities (although they may occur in developmentally normal children as part of an idiopathic epilepsy syndrome) and consist of brief loss of postural tone, often resulting in falls and injuries (hence, some patients need helmets).

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The current system comprises two major categories: localization-related syndromes and generalized-onset syndromes. Physicians ideally would classify their patients' seizures by using the classification for seizure types and make a syndromic diagnosis, if possible.

Localization-related epilepsies and syndromes include the following:

• Idiopathic, with age-related onset

• Benign childhood epilepsy with centrotemporal spikes

• Childhood epilepsy with occipital paroxysms

• Symptomatic

• Mesial temporal lobe sclerosis

Generalized epilepsies and syndromes include the following:

• Idiopathic, with age-related onset

• Benign neonatal familial convulsions

• Benign neonatal convulsions

• Benign myoclonic epilepsy of infancy

• Childhood absence epilepsy (pyknolepsy)

• Juvenile absence epilepsy

• Juvenile myoclonic epilepsy (JME)

• Epilepsy with grand mal seizures on awakening

• Idiopathic and/or symptomatic infantile spasms

• Lennox-Gastaut syndrome

• Epilepsy with myoclonic astatic seizures

• Epilepsy with myoclonic absences

• Symptomatic

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Video EEG monitoring is the criterion standard for classifying the type of seizure or syndrome or for diagnosing pseudoseizures. This study can be performed to rule out an epileptic etiology with a high degree of confidence if the patient has demonstrable impairment of consciousness during the spell in question, without abnormality on the EEG. Video EEG is also used to characterize the type of seizure and epileptic syndrome to optimize pharmacologic treatment and for presurgical workup.

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A recent study determined that ethosuximide and valproic acid are superior in effectiveness compared with lamotrigine; valproic acid was found to have a higher rate of side effects. If absence seizures are present along with other seizure types (eg, generalized tonic-clonic seizures, myoclonic seizures), many neurologists would choose valproic acid, lamotrigine, or topiramate. Do not use carbamazepine, gabapentin, or tiagabine because these drugs may exacerbate absence seizures. It is uncertain whether pregabalin, a medication related to gabapentin, has the same risk.

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Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.

Cite this article: Amy Kao. Quiz: Test Your Knowledge of Epilepsy and Seizure-related Conditions. Medscape. Jan 12, 2016.