As you mention that you mum was diagnosed with dementia
, which is common at her age, her symptoms is most likely due to dementia. Dementia is chronic progressive degeneration
of brain function form memory lost to inability for personal care. As a result of progressive degeneration due to dementia, convulsion
can set in. What you described for you mum is probably convulsion characterized by blackout
and lost of bowel control. Strokes is less likely but not impossible. For stroke we would have expected sudden convulsion-lost of bowel control and blackout- and rapidly deteriorating state. Investigation to further investigate the situation my be necessary. Your doctor, who I advise you to contact, will know about this.
hope this is helpful