A 7-year-old child has a 2-year history of staring episodes lasting 5–15 seconds with eye fluttering, occurring multiple times daily. EEG shows 3-Hz spike-and-wave discharges on hyperventilation. The child has normal intelligence and no structural brain lesion. Which of the following statements about the FIRST-LINE drug for this condition is CORRECT?

• A Valproate is preferred over ethosuximide due to lower risk of absence-to-generalized tonic-clonic conversion
• B Ethosuximide acts by blocking T-type calcium channels in thalamic neurons ✓
• C Carbamazepine is highly effective and first-line for childhood absence epilepsy
• D Lamotrigine has no role and worsens absence seizures

Explanation

Childhood absence epilepsy is driven by abnormal thalamocortical rhythmicity mediated by T-type (low-voltage activated) calcium channels in thalamic neurons. Ethosuximide selectively blocks these T-type channels, reducing the oscillatory activity that generates 3-Hz spike-wave discharges. Both ethosuximide and valproate are first-line options; ethosuximide is preferred if absence is isolated (no GTCS), while valproate is chosen if GTCS coexist. Carbamazepine can paradoxically worsen absence seizures. Lamotrigine is a second-line alternative.

Reference: Ghai Essential Pediatrics, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.