Hey Claire!! Hope your mum is doing better..
Almost nurse here (took the courses never followed through with boards etc.) I'll tell you what I know about TIA.. This info is based on my studies so don't take it as medical advice etc set in stone and it may be totally different for your mum. In other words, not medical advice of any sort just offering my knowlege on the topic to help you understand what may be going on
Transient ischemic attack (TIA)
A transient ischemic attack is usually caused by temporary interruption of blood to a part of the brain and results in a sudden, brief decrease in brain functionality. It is only for a brief period of time. It is also usually a "freak" occurance and many don't experience it again. It's good she's following up with a specialist to check it all out. In most cases the patient is fine and continues on normally. Since she doesn't remember that day, that's more than likely the part of the brain the disturbace or interruption of blood flow affected. I'm sure she'll be fine. One thing I get irritated about is when the nurse/physician tries to explain what happened in medical lingo.. sure makes it hard for the "lay person" to interperet. Hope this helps! Keep us posted.