Which of the following is a first-line treatment for absence seizures?

Ethosuximide is recognized as the first-line treatment for absence seizures. This medication specifically targets the underlying mechanisms that cause these types of seizures by reducing the frequency and severity of seizures. Absence seizures are characterized by brief episodes of loss of consciousness, often with minimal motor activity, and ethosuximide is particularly effective in managing this unique type of seizure due to its ability to modulate calcium channels in the thalamic neurons, which play a crucial role in generating the seizure activity.

While other medications listed may be effective for different types of seizures—such as phenytoin and carbamazepine for focal and generalized tonic-clonic seizures—none are recommended for absence seizures. Midazolam is often used in emergency situations for seizure control but does not serve as a primary treatment for absence seizures. The specificity of ethosuximide for absence seizures makes it the preferred choice among clinicians treating this condition.