Childhood Absence Epilepsy

A 7-year-old girl presents with multiple daily episodes of behavioral arrest lasting 8–10 seconds, during which she stares blankly with subtle eyelid fluttering, then resumes activity without postictal confusion. Hyperventilation reliably reproduces an episode. EEG shows a generalized, bilaterally synchronous discharge. The feature marked **B** in the diagram—the regular 3 Hz spike-and-wave frequency—is the electrographic hallmark of childhood absence epilepsy. This pathognomonic rhythm is generated by thalamocortical oscillations driven by which of the following ion channels?

A 7-year-old girl is brought to the pediatric clinic with episodes of "staring into space" lasting 5–10 seconds, occurring multiple times daily. During these episodes, her mother notes subtle eyelid fluttering but no loss of consciousness. She resumes activity immediately with no post-ictal confusion. Hyperventilation in the clinic reproduces a spell. An EEG obtained during hyperventilation shows bilaterally synchronous, symmetric generalized spike-and-wave complexes at 3 Hz on a normal background. The mechanism involves aberrant thalamocortical T-type calcium channel oscillations. The drug marked **B** in the diagram is the first-line agent for this seizure syndrome. Which of the following best describes why carbamazepine and phenytoin are contraindicated in this condition?

A 7-year-old girl is brought to the paediatric neurology clinic by her mother, who reports that the child has been having multiple brief episodes of unresponsiveness throughout the day, often mistaken for "daydreaming" or inattention at school. During the clinical examination, hyperventilation for 4 minutes is performed, and the child experiences a clinical absence seizure with a vacant stare. The EEG during this episode shows the pattern marked **A** in the diagram. Which of the following is the most appropriate first-line antiepileptic drug for this patient?

A 7-year-old girl presents with frequent episodes of brief staring spells occurring 20–30 times daily at school. Each episode lasts 5–15 seconds with abrupt onset and offset, subtle eyelid fluttering at 3 per second, and no postictal confusion. Hyperventilation in the clinic triggers a typical spell. EEG during hyperventilation shows the pattern marked **A** in the diagram. Which of the following is the most appropriate first-line antiepileptic drug for this diagnosis?