When do you consider discontinuation of treatment in pediatric patients who have responded well to preventive migraine medications?

This is an excellent question and not necessarily straightforward to answer, as there are no current definitive guidelines to determine optimal duration of successful migraine preventive treatment and the best method of preventive medication discontinuation.

If you look at the most recent pediatric practice update for migraine prevention, the recommendations state clinicians should periodically monitor medication side effects and adverse events by prescribing preventive medication, and counsel patients and families in terms of potential risks/benefits of stopping migraine with preventive medication once good control is achieved (Oskoui et al., PMID 31529477).

A more recent review on this topic (albeit not pediatric-specific), I believe, offer...