I’m sorry to hear about your husband’s stroke. Seizures happen in approximately 5% of people who have strokes which are caused by brain damage and/or abnormal electrical activity.
I believe you made a wise choice in going to Mayo Clinic since they have a top notch level 4 Epilepsy Center where your husband will no doubt be evaluated by an Epileptologist who is a neurologist specializing in epilepsy.
Does your husband have Focals (use to be called partial seizures or localized seizures) are seizures which usually affect only one side of the brain) or Generalized (Affects the entire brain with loss of consciousness) Tonic Clonic (Old terminology Grand Mal)
Unfortunately memory and cognitive problems are very common side effects when taking Anticonvulsants. I assume the Epilepsy Center hasn’t talked to you about what tests will be done.
Aside from the usual Neurological evaluation they may do an EEG, perhaps a sleep deprived EEG or most likely if he’s admitted they may do (VEEG) Video telemetry EEG. They will monitor his brain waves, heart rate and video him. They may take him off his meds so he’s more prone to have seizures and they may want him to stay awake all night which usually produces a better brain wave report and evaluate the physical characteristics during the seizure to hopefully pinpoint the seizure focus (where the seizure begins) to better determine what type of seizure it is which will in turn help them prescribe the most appropriate medication.
Unlike when I was first diagnosed (Over 50 years ago) with epilepsy the only imaging available at the time were standard x-rays, nowadays they have a myriad of different scans they could do to check various things even at the cellular level.
Best of luck,