Dear care taker, Welcome to health care magic. Thanks for being so interested in your husbands health. Cortisone injections cause muscle spasms and twitching. Cortisone is not a curative drug. It is an anti inflammatory drug. Among it s side effects are muscle aches and spasms. This depends on the site of the injection and the frequency of injections. I will directly answer your question by informing you that if cortisone were not to work, the muscles would not be twitching. This is normal . Please see a physician, for the purpose of obtaining a opinion about being prescribed a muscle relaxant like tizanidine or diazepam. I hope this helps. Take care.