I actually have a version of autonomia. Which is also called dysautonomia in the general term. There are various forms of dysautonomias. (ie: POTS, Primary (or Pure) Autonomic Failure and the most severe version (as far as prognosis is concerned) is Multiple System Atrophy. There are others as well.
Yes, I do have numbness with my PAF. Commonly, what I have found, anyway in my many years of dealing with this, is that a patient is often diagnosed with various seemingly unrelated syndrom's or other diagnosis'. For example, I have neuropathies that are attributed to the numbness. Fibromyalgia that attribute to the generalized pain. Interstitial Cystitis and Neurogenic bladder. Sinus Tach for my cardiac issues, history of aspiration pneumonia. I could go on... It does not mean that these diagnosis' are not correct, but the failure of the autonomic system to work properly simply affects many of the parts of your body that you do not actively have control of.
As far as antidepressant use, well, that is actually a common treatment for autonomic dysfunctions. The seratonin issues with the use of antidepressants appear to be a factor in the benefits here. It is not FOR depression, but the mechanism of the drug, appears to help regulate the autonomic 'misfirings' so to speak. Also, autonomic disorders tend to 'feed on adrenaline', so think of it like this, the antidepressant, helps to maintain an even level of this and the affect it has in a person with an autonomic issue...
I hope this helps some one. You have to be persistant in getting diagnosed with one of these disorders. I tried for ten years to find out the 'big picture' of what was going on and in that time, I lost track of the doctors that I had to see in order to finally get all of the answers to get that diagnosis. Many tests, many attempts, but in the end, it is simply control the symptoms and find what works.
I've been experiencing numbness/tingling, vibrating sensation throughout my spine, gut, chest organs, limbs, hands and feet, among numerous other symptoms. They used to be intermittent but have recently become chronic and seem to be worse on waking than at bedtime. It's not unusual for them to be accompanied by mild palpitations on waking. I don't believe I have dysautonomia based on what I've read so far but am not ruling anything out. I'm hoping to get muscle, nerve and/or skin biopsies to see if something can be identified by means of those to explain at least some of my symptoms. You may want to research the uses of those tests in addition to testing for dysautonomia.
Just my opinion, but I would avoid the antidepressants if you're not depressed or anxious, even if you're depressed or anxious about not being able to get a diagnosis.
Dysautonomia/pandysautonomia/autonomic neuropathy/dysfunction--read as much as you can on it and go back to your doctors and tell them what you find if it fits your symptoms. I don't know if numbness is a symptoms of dysautonomia but the feeling faint could be and the rapid pulse/tachycardia. You might want to read on POTS (postural orthostatic tachycardia syndrome). I believe it is basically a rapid drop in blood pressure and rapid pulse rate when going from a sitting or lying down position to standing, but read up on it and see if it describes what you experience. The doctor can test your BP and pulse in his office after you stand, but a Tilt table test even better measures the drop in BP if you have this syndrome. Don't let anyone tell you it means nothing/will disappear/is all in your head. If you have BP kit you might want take your BP when sitting/lying and then stand up and take it a couple minutes (I believe) after standing-or whenever you feel faint.