Depends. It depends on what you mean by violent. If by violent you mean life or limb threatening then you will need to use medication (oral or injectable) to terminate the event. You can also use similar meds to prevent the fits. Teaching self soothing skills and hypnosis can be of value to prevent the fits of rage as well.
Combined approach. best dealt with as a combined approach with cognitive behavioral therapy, provided by a behavioral psychologist and medication. amantadine is particularly effective although other medications have been used. speak to your pediatrician for referrals.