Possibly. As in, possibly a stroke, but possibly by Mike giving him a Stone Cold Stunner in the parking lot of Los Pollos Hermanos.This is from the Breaking Bad wikia:
Hector was rendered invalid possibly from a stroke or some form of motor neuron disease; such as amyotrophic lateral sclerosis (ALS)/Lou Gehrig's disease.
I don't think it's going to be a major part of the show, but who knows.