MIAMI — Absence epilepsy seizures can be differentiated from daydreaming or ADHD with an office procedure involving nothing more than a piece of paper.
“Hyperventilate the child by having them blow on a paper or on their own, and you will see loss of consciousness [if they have absence epilepsy],” said Dr. Michael S. Duchowny. “It's a very easy thing to do in your office.”
In the absence of a piece of paper, one tip is an obvious onset and offset of the transient loss of consciousness characteristic of absence seizures. “You cannot snap the child out of it during an episode,” Dr. Duchowny said.
EEG can confirm the diagnosis of absence epilepsy. The readout will show bilateral, symmetric, and synchronous 3-Hz spikes and wave discharges against a normal EEG background, Dr. Duchowny said.
The age at which a child presents with absence seizures is an important consideration. Physicians who suspect a child is having absence seizures—which were formerly known as petit mal epilepsy—should rule out other conditions, said Dr. Duchowny, director of the comprehensive epilepsy program at Miami Children's Hospital.
Onset of absence seizures is usually at 5–12 years old. “A red flag should go up with any child who comes into your office before age 5 with absence seizures. This is unusual—you need to look for other developmental disorders,” Dr. Duchowny said at a meeting sponsored by Miami Children's Hospital.
First-line treatment includes antiepileptic drugs (AEDs) like ethosuximide, valproic acid, or clonazepam, Dr. Duchowny said. Newer AEDs are also effective, such as lamotrigine, levetiracetam, or topiramate. AEDS to avoid include carbamazepine, oxcarbazepine, phenytoin, and gabapentin. Dr. Duchowny received an honorarium from and is on the speakers bureau for GlaxoSmithKline Inc.
Despite timely treatment, children with absence epilepsy should be monitored for adverse psychosocial effects, Dr. Duchowny said. “If one looks long term at children with absence seizures, sometimes the outlook may not be as favorable as we think.”
For example, adults with a history of childhood absence seizures, even when they remained seizure-free, had greater difficulty with academic, social, and behavior domains, according to a cohort study (Arch. Pediatr. Adolesc. Med. 1997;151:152–8). The mean follow-up for the 58 patients in the study was 23 years.
Absence seizures can occur as a discrete seizure type or a robust epilepsy syndrome with associated symptoms. If the child has the syndrome, physicians and parents might see frequent automatisms, such as lip smacking or eye closure, especially during longer seizures.
“Absences tend to disappear around age 15 or 16 years,” Dr. Duchowny said. “You can tell families these seizures will not recur later in life. They 'time on' but they also 'time off.'” If the child experiences mixed seizure types, such as concomitant generalized tonic-clonic seizures, they can persist in some patients, he added.
Absence seizures must be the initial and most prominent type of seizure for the diagnosis of childhood absence epilepsy. “By and large, these children are neurologically healthy,” Dr. Duchowny said.
In contrast, a small subset of patients can have atypical absence seizures. Poor seizure control and persistence of epilepsy are more common with atypical seizures. “These typically occur in children with some type of associated neurologic disability,” Dr. Duchowny said. The seizures generally occur in children with development delay and often coexist with other seizure types, especially tonic-clonic, myoclonic, and tonic seizures. “These children often have a much poorer neurodevelopmental outcome, including less control of seizures, even with medication.”