Is dysautonomia a "garbage can" dxs? What would constitute a definitive dxs in this case?

No, I wouldn't call it that.

It's just that many different medical problems can lead to dysfunction of the autonomic nervous system either locally or systemically.

The symptoms would suggest dysautonomia - the subjective.

Then a differential diagnosis of possible causes would be made and a logical series of testing would begin - the objective.

After all tests, and assessment would hopefully include a positive finding to indicate the cause - lab evidence of diabetes, evidence of liver disease / alcoholism, or possibly a tissue biopsy showing pathological changes in the nerve fibers. Sural nerve biopsies are sometimes done.

Here's a site for this - http://www.nlm.nih.gov/medlineplus/ency/article/00...

The hope is that an effective treatment would follow.

I like this site http://www.ninds.nih.gov/disorders/dysautonomia/dy...

"Dysautonomia can be local, as in reflex sympathetic dystrophy, or generalized, as in pure autonomic failure. It can be acute and reversible, as in Guillain-Barre syndrome, or chronic and progressive. Several common conditions such as diabetes and alcoholism can include dysautonomia. Dysautonomia also can occur as a primary condition or in association with degenerative neurological diseases such as Parkinson's disease. Other diseases with generalized, primary dysautonomia include multiple system atrophy and familial dysautonomia."

Compare this to dementia - dysfunction of the CNS / mental functioning.

Look at the differential diagnosis : Causes of Dementia

http://www.webmd.com/alzheimers/guide/alzheimers-d...

* Diseases that cause degeneration or loss of nerve cells in the brain such as Alzheimer's, Parkinson's and Huntington's.

* Diseases that affect blood vessels, such as stroke, which can cause a disorder known as multi-infarct dementia.

* Toxic reactions, like excessive alcohol or drug use.

* Nutritional deficiencies, like vitamin B12 and folate deficiency.

* Infections that affect the brain and spinal cord, such as AIDS dementia complex and Creutzfeldt-Jakob disease.

* Certain types of hydrocephalus, an accumulation of fluid in the brain that can result from developmental abnormalities, infections, injury, or brain tumors.

* Head injury -- either a single severe head injury or longer term smaller injuries, like in boxers.

* Illness other than in the brain -- kidney, liver, and lung diseases can all lead to dementia.

Many problems are like this in medicine - like "Dr. House" portrays on TV.

For various illnesses, we have to consider common or uncommon infections with common or uncommon presentations.

It may be an autoimmune disorder causing system dysfunction / disease.

It could be a degenerative disease - acquired or familial

It could be toxicity from a multitude of possible chemical agents.

We always have to consider all possibilities when attempting to make a diagnosis. That's why internal medicine and neurology are mostly thinking jobs.

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http://en.wikipedia.org/wiki/Dysautonomia

It is the first part of a diagnosis deductive reasoning process after ruling out toxic and viral contingent conditions for the initial symptom presentation. Dysautonomia is a low specificity classification introduced as a hypothetical proposition after other etiological conditions are deducted from the theoretical constructive diagnostic process.

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