Well I am new to the game and still waiting to see the neurologist for diagnosis. I work full time but have had 1 month off work this year with the sudden onset and medication.
I am in the lucky position where I can work from home (or anywhere I can get internet connections from a laptop) but then I can be called upon at any time to work if my staff can't resolve the issue.

On the work anywhere the best I ever did was handle calls from around a camp fire one night sitting on a beach, turned out I was 1km from the caller .
Worst was from a casualty bed after a suspected heart attack, turned out it was stress. Nurses were not impressed until they worked out I was fixing a health database for a different hospital who needed the data asap.