There is a bus service from Orio to Brescia run by Autostradale. Maybe there you could connect with a bus to Desenzano or maybe even Limone.
see the site
AUTOSTRADALE: in autobus con un click.
also check the page on help for people with disabilities. "L'impegno per i disabili"
I've never used it, just what I found on the internet.
Cheers
Dora