What are the diagnostic criteria and treatment options for absence seizures?

From the Guidelines

Absence seizures are diagnosed based on clinical presentation and EEG findings, with first-line treatment being ethosuximide or valproic acid, and lamotrigine as an alternative, aiming to achieve at least 2 seizure-free years before considering discontinuation. The diagnostic criteria for absence seizures include brief episodes (typically 5-30 seconds) of sudden cessation of activity with a blank stare, sometimes accompanied by automatisms like eye blinking or lip smacking, without post-ictal confusion, as defined by the International League Against Epilepsy (ILAE) 1. EEG shows characteristic 3 Hz spike-and-wave discharges, which is a key diagnostic feature.

When it comes to treatment, the goal is to achieve good seizure control while minimizing side effects. Ethosuximide is typically started at 250 mg daily and gradually increased to 20-30 mg/kg/day divided into two doses, with therapeutic blood levels of 40-100 μg/mL. Valproic acid is an alternative, starting at 10-15 mg/kg/day and increasing to 30-60 mg/kg/day in divided doses, with target levels of 50-100 μg/mL. Lamotrigine may be used at 0.5 mg/kg/day initially, gradually increasing to 5-15 mg/kg/day. It's essential to regularly monitor for medication side effects, such as gastrointestinal issues with ethosuximide, liver function with valproic acid, and skin rash with lamotrigine.

Some key points to consider in the management of absence seizures include:

• The importance of accurate diagnosis based on clinical presentation and EEG findings
• The selection of appropriate first-line treatment, such as ethosuximide or valproic acid
• The need for regular monitoring of medication side effects and adjustment of treatment as necessary
• The goal of achieving at least 2 seizure-free years before considering discontinuation of treatment, as stated in the guidelines 1.

Overall, the management of absence seizures requires a comprehensive approach that takes into account the individual patient's needs and circumstances, with the ultimate goal of achieving good seizure control and improving quality of life.

From the FDA Drug Label

Valproic acid is indicated for use as sole and adjunctive therapy in the treatment of simple and complex absence seizures, and adjunctively in patients with multiple seizure types which include absence seizures. Simple absence is defined as very brief clouding of the sensorium or loss of consciousness accompanied by certain generalized epileptic discharges without other detectable clinical signs. Complex absence is the term used when other signs are also present. The recommended initial dose is 15 mg/kg/day, increasing at one week intervals by 5 to 10 mg/kg/day until seizures are controlled or side effects preclude further increases.

The diagnostic criteria for absence seizures include a very brief clouding of the sensorium or loss of consciousness accompanied by certain generalized epileptic discharges. Key points for diagnosis and treatment of absence seizures are:

• Definition: Simple absence is characterized by a brief clouding of the sensorium or loss of consciousness, while complex absence includes other signs.
• Treatment: Valproic acid is indicated for the treatment of simple and complex absence seizures.
• Dosage: The recommended initial dose of valproic acid is 15 mg/kg/day, with increases of 5 to 10 mg/kg/day every week until seizures are controlled or side effects occur 2. The treatment options for absence seizures include valproic acid, which can be used as sole or adjunctive therapy 2.

From the Research

Diagnostic Criteria for Absence Seizures

• Absence seizures are characterized by a sudden loss of awareness and an electroencephalogram (EEG) typically showing generalized spike-wave discharges at three cycles per second 3.
• The diagnosis of absence seizures is based on clinical features and EEG findings, and can be divided into typical, atypical absences, and absences with special features 3.
• Typical absences are brief, generalized seizures of sudden onset and termination, with impairment of consciousness and generalized 3 to 4Hz spike/polyspike and slow wave discharges on EEG 4.

Symptoms of Absence Seizures

• Impairment of consciousness may be severe, moderate, mild, or inconspicuous, and is often associated with motor manifestations, automatisms, and autonomic disturbances 4.
• Motor symptoms can include clonic, tonic, and atonic components, alone or in combination, and myoclonia, mainly of facial muscles, is the most common 4.
• Absence seizures can be triggered by photic, pattern, video games stimuli, and mental or emotional factors, and are often precipitated by hyperventilation in about 90% of untreated patients 4.

Treatment Options for Absence Seizures

• Valproic acid, ethosuximide, and lamotrigine are first-line therapies for absence seizures, and can be used alone or in combination 4.
• Ethosuximide is the optimal initial empirical monotherapy for children and adolescents with absence seizures, with a faster onset of efficacy compared to valproic acid and lamotrigine 5, 6.
• Valproic acid is effective in controlling absences, but may be undesirable for some women, and lamotrigine may worsen myoclonic jerks and has a higher risk of skin rashes 4, 6.
• Clonazepam and acetazolamide may be useful adjunctive drugs, particularly in absences with myoclonic components 4.

Long-term Effectiveness of Treatment

• The long-term efficacy and tolerability of ethosuximide, valproic acid, and lamotrigine as initial monotherapies for patients with newly diagnosed childhood absence epilepsy have been evaluated, with ethosuximide showing a faster onset of efficacy and similar long-term effectiveness to valproic acid and lamotrigine 5, 6.
• The freedom-from-failure rates for ethosuximide and valproic acid were similar and higher than the rate for lamotrigine at 12 months, with a significant difference in treatment failures due to lack of seizure control and intolerable adverse events among the treatment groups 6.