Is there are cure for dystonia?

Sometimes: Dystonias come in many forms. Some are chronic, some progress over time, and some are transient. Some dystonias are reactions to other medications. "swimmer's cramp" is a type of dystonia. A variety of treatments are possible, and even with no treatment, they may get better spontaneously.

No just modification: There are many forms of dystonia. Some cases are transient and resolve on their own. Some cases are progressive and get much worse over time. Some are modified with treatment. Some seem to disappear following procedures such as deep brain stimulation, but can recur.