Hi, yours sister episodes of sweatings and shaking of limbs on the background age and ALzheimers dementia could be due to many causes. Actually further details are necessary to comment on the cause. She might be experiencing a seizure like episode or a hypoglycemia or hypotensive episodes. The precaution necessary is to have attendant nearby when she is walking. Clear observation of her behaviour and other symptoms are helpful to know thecause of present episodes. When she has the episode she has to be made to rest on bed on one side and to see that she is getting enough air. However she needs to be shown early to doctor to know the cause. Bye