With regards to the age of the patient primary idiopathic epilepsy is the most likely underlying cause of the seizural activity here.
Cranial fossa diseases that are associated with macroscopic structural changes can be ruled out largely. However, as inflammatory, metabolic/toxic and neurodegenerative disorders cannot be ruled out based on negative imaging findings the study should be complemented by a CSF examination at least. In case of the strong clinical suspicion of caudal fossa/brain stem involvement or should the imaing finidngs not parallel the clinical context MRI would be another option for further definition.