A 7 year-old has episodes of unresponsiveness lasting 10-20 seconds. What is considered the first-line therapy for this disorder?

The first-line therapy for a child experiencing episodes of unresponsiveness lasting 10-20 seconds is ethosuximide. This medication is specifically indicated for the treatment of absence seizures, which fit the description of unresponsive episodes in this age group.

Ethosuximide works by reducing the frequency of these seizures by inhibiting calcium channels in the thalamic neurons, which play a critical role in the generation of these absence seizures. Its effectiveness and favorable side effect profile make it the preferred choice for managing this type of seizure disorder, particularly in pediatric patients.

In contrast, carbamazepine is primarily used for focal and generalized tonic-clonic seizures but is not effective for absence seizures. Gabapentin is generally used for neuropathic pain and partial seizures but is not a first-line treatment for absence seizures. Topiramate is effective for a variety of seizure types, including focal seizures and is used off-label for others, but it is not the first-line therapy for absence seizures specifically. Thus, ethosuximide is the most appropriate medication in this scenario.