I had asked for some further information and have not heard back.
When dealing with severe orthostatic hypotension that is not responding to midodrine or flucrocortisone, there are several options to consider and I asked the above questions to ascertain whether these other options have been tried.
It is important to consider any other medicines that may be making the orthostatic hypotension worse. Even in people in whom the primary reason for the orthostatic hypotension is a neurologic condition, these medicines may be making it worse. Of course, each of these medicines were started for a medical condition that will typically still need treatment, so it is usually not as simple as just stopping any drug that may be contributing to the problem. Of the medicines that he is taking, the amiodarone and the gabapentin are the medicines that are most likely to be contributing to orthostatic hypotension, but the Cymbalta and Keppra also could be a factor.
It also may help to implement certain lifestyle changes. You mention that he has been trying TED hose, but there are several other interventions that can be tried. He has likely been told to increase the intake of salt and water. It may help to augment the TED hose with an abdominal binder. It may help to place 4-6 inch blocks under the feet at the head of the bed, so that he sleeps at an angle, and this is more effective than simply sleeping on more pillows.
As for medicines, the midodrine and fludrocortisone are the common medicines that are used for this. There are a couple of other medicines that can be considered, including pyridostigmine or droxidopa, although it is more common to try the above interventions before trying one of these medicines.
If I can provide any further information, please let me know.