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Your son is having Seizures ,it is good that he is taking regular treatment.
shows scar even tough his EEG is normal,please continue to give medicine regularly with periodic check ups.
Take care of his diet and exercise to avoid weight gain.
He has to continue for long time may be 2 years of seizure free interval then the treating Neurologist
may try to withdraw the drug there is more than 50% chance his seizures are not there if it comes again then anti epileptic drug is to be continued for long time.
Please do not withdraw medicine yourself.