sparkler I am an expert on panic attacks suffered for years mine have been due to medical condition hyperthyroidism but still exactly the same as someone without medical condition.
I understand all to well how horrible they are.
Basically your body releases chemicals that it would release in a life threatening situation
So you feel clammy, sweaty hot & cold at same time, frightened, heart thumps in chest, find it hard to breath, just as you would if you were say being chased by a madman or something awful was about to happen you.
Its called fight or flight where your body naturally produces adrenalin to take on whats about to be thrown at it. In a life threatening situation this helps you to survive.
When those symptoms occur for no apparent reason the natural assumption is that you are about to die! Which of course makes you panic more and then it spirals out of control and can leave you on the floor a gibbering mess (been there)
Thats really how to sum it up.
You can control them by learning about what is happening and therefore talking yourself round when it happens by telling yourself what is happning which breaks the cycle and stops them.
Hope this helps your mum.
There is a great book by claire weekes called self help for your nerves.
Nik