Thanks for posting your query.
is a disease with headache is one of its symptoms.
Few medications regarding migraine are available for the cure of headache and few for prevention of migraine attacks in future.
As such there is no permanent cure of Migraine.
Valance OD contains Divalproex
and it is one of the commonly used medicine for the prevention of migraine.
You should continue with the valance, if not facing any side effects.
Regarding time duration, its very difficult to comment.
You may discontinue Valance under guidance of your treating neurologist
and keep on observation.
If headache occurs after stopping medication then you have to take medicines.
Dr. Mayank Bhargava