What has caused Mom's decline lower extremity mobility?
Your gut instincts are right on. Usually, there are no simple answers to why older people have multiple falls. I have read through all the things that your mother has been through in the past 2 months, and she has been through alot. It also sounds like she has mulitple medical problems, including dementia, asthma or emphysema, hearing loss, cerebrovascular disease, osteoarthritis, and high cholesterol. I am sure that all these problems are playing a role in her recent poor health. Sometimes, after being hospitalized, it takes some people a few weeks to build up their strength and recooperate. She may just need some more time to build her stamina.
Reading through your letter, several thoughts entered my mind. Your mother is at increased risk of falls from her dementia alone, since as it progresses, people do lose the ability to walk safely. Also, she has significant left carotid artery stenosis (cerebrovascular disease), which means that she is at increased risk for strokes. I know that the MRI and CT did not show any new strokes, but I would wonder if she did have a small stroke recently, especially after her symptoms of a "headache", followed by a syncopal episode with a decline in function. You did not mention if she was on aspirin- I would ask her doctors to consider starting her in light of her carotid ultrasound results.
I have reviewed your mother's medications- they all seem pretty normal to me. She is on a good number of medications for her breathing problems. I will mention that she really should stop smoking, as this is really hurting her health at this point. It also will make her risk for strokes higher and can make her dementia progress more quickly.
Regarding her poor walking, I would ask her physician if home physical therapy would help. It sounds like she needs to be evaluated and given exercises to strengthen her legs and make her more confident when walking. She should continue to use the walker for safety.
For someone who is a high risk for falls, you should check her home and make sure it is as safe as possible. 1) All throw rugs should be removed, along wiht any clutter. 2) If she lives alone, you can get a device like Lifeline for her to wear in case she does fall when she is alone and needs help. 3) Keep rooms well lighted. 4) Remove any furniture that gets in the way of the walker. 5) Make sure she wears good shoes when getting up. Socks and slippers are not supportive, and can make falls more likely.
Lastly, your mother is not on any medications to help strengthen her bones. Since she is a smoker, she is at high risk for osteoporosis, so I would check with her doctor to see if anything else should be added, like a calcium supplement. Good luck!