Epilepsy is common, occurring in approximately 1% of people, with peak onset in infancy and childhood. It can have severe consequences in the developing brain, resulting in "hard wiring" for continued seizures and permanent cognitive, psychosocial, and motor delays. The critical factor in determining treatment and prognosis is recognizing the specific epilepsy syndrome.
The types of seizures factor into identifying epilepsy syndromes. One type, generalized seizures, includes generalized tonic-clonic seizures (formerly called "grand mal" seizures), tonic seizures, atonic seizures, or absence seizures (formerly called "petit mal" seizures).
Partial seizures, the other type, start in focal area of the brain and can spread to other areas. Simple examples of partial seizures (with no consciousness alteration) are "auras," such as detecting a bad odor or taste, or experiencing déjà vu, jamais vu, or a feeling of dread. An example of a complex partial seizure (focally generated, but with alteration of consciousness) would be a staring spell, followed by head and eye deviation, with associated automatisms or stereotypic, repetitive movements.
Other signs and symptoms also help identify epilepsy syndromes: age of onset; clinical seizure semiology; medical history; developmental/academic history; family history; physical examination (including a complete neurologic examination); and diagnostic tests, including EEG, MRI, and other exams.
Infantile spasms
This is a commonly missed generalized epilepsy syndrome because the spasms can easily be confused for normal baby movements.
This syndrome typically occurs between 4 and 10 months. It is characterized by clusters of flexor or extensor "spasms" that frequently occur when an infant awakens, during drowsiness, or upon sleep. Spasms can be subtle, perhaps characterized only by a slight head drop or eye rolling, in clusters.
Causes of infantile spasms include brain malformations, infection, chromosomal abnormalities, stroke, inborn metabolism errors, or tumors. Early recognition is critically important as infantile spasms can develop into intractable epilepsy. If they are recognized within 4-6 weeks of onset, the ability to eliminate the infantile spasms and hypsarrhythmia EEG pattern is improved. The prognosis also is improved.
The therapy mainstay is adrenocorticotropic hormone (ACTH), injected daily for 6-8 weeks. Prospective studies indicate that three-quarters of patients experience remission with this therapy. However, for children with tuberous sclerosis and infantile spasms, many physicians will use vigabatrin (Sabril) as a first-line therapy.
Infants with infantile spasms generally have a poor prognosis, with high risks of continued epilepsy, cognitive impairments, and developmental delays. This is a testament to the catastrophic consequences of even brief, recurrent seizures in developing brains.
Other generalized epilepsy syndromes include childhood absence epilepsy, juvenile absence epilepsy, and juvenile myoclonic epilepsy (JME) – all idiopathic with a probable genetic predisposition. Many such syndromes are secondary to mutations in the T-type calcium channel or gamma-aminobutyric acid channel.
Childhood absence epilepsy
It typically presents between ages 4 and 9 years. It is associated with absence seizures – brief episodes of staring, with no postictal phase, occurring multiple times daily – with a 17% chance of comorbid generalized tonic-clonic seizures. Ethosuximide and valproate are the only antiepileptic drugs with proven efficacy.
Juvenile absence epilepsy
It presents similarly to childhood absence epilepsy, but after age 10 years. The risk of generalized tonic-clonic seizures, in addition to absence seizures, is 80%.
Juvenile myoclonic epilepsy
JME presents at puberty, usually with generalized tonic-clonic seizures and myoclonic seizures in the morning. Absence seizures are less prominent or nonexistent. JME is lifelong epilepsy. Appropriate treatments include valproate, lamotrigine, or levetiracetam.
Benign rolandic epilepsy
Also called benign epilepsy with central-temporal spikes, it is the most common childhood epilepsy syndrome. Benign rolandic epilepsy is idiopathic, with a probable genetic predisposition, and generally surfaces in otherwise healthy, cognitively normal children between the ages of 5 and 8 years.
Seizures generally occur soon after falling asleep or in the morning between 4 a.m. and 6 a.m. They usually begin focally with facial twitching and drooling, followed by rapid secondary generalization to a tonic-clonic seizure. Typically infrequent, the seizures are commonly associated with sleep deprivation. The physical examination is normal, but a sleep-deprived EEG demonstrates drowsy and sleep-activated central-temporal spikes, usually bilateral. This syndrome goes into remission at puberty and does not always require antiepileptic medication.
Localization-related epilepsy syndromes
These syndromes that result from remote symptomatic lesions in the brain are more problematic. If the first one to two antiepileptic medications do not control the epilepsy, it is unlikely that additional antiepileptic medication trials will work. Even with complete seizure control, patients can rarely taper off medication. For patients whose seizures continue, epilepsy surgery may be the best option.