Can a grand mal seizure cause permanent brain damage?

Not likely: A grand mal seizure may originate from pre-existing permanent brain damage, or from a new event such as a tumor or vascular lesion. The events in a grand mal seizure, although dramatic, usually do not increase brain damage unless they are recurrent. You can injure the rest of your body depending upon what you were doing at the time of the seizure. You should see a neurologist; seizure specialist.