I had a look for you and find that although fairly rare, there are documented cases of myoclonus following epidural injections, so in answer to your question....yes, the epidural injection could have caused your husband's condition.

There was also a discussion here on NeuroTalk around 2 years ago about a similar situation. Hopefully those posters will still be around to reply to your thread.

Here's the link for you to have a read.
http://neurotalk.psychcentral.com/thread2376.html