This info is from the pamphlet my doctor gave me on them. I think you should really research any treatment before you do it. There have been times that I have been so desperate for any relief that I just let them do what ever they recommended and regretted it later.
Good luck. I really hope it works for you.

"An intravenous lidocaine infusion is used to assess the potential benefits of lidocaine (a numbing medication) and related medications to manage your pain. Depending on the specific cause of the pain some patients report immediate, temporary relief of pain during the lidocaine infusion.

Other patients report sustained relief for one to four weeks after the infusion. If you notice an improvement in your pain during the infusion, please take note as to how long the beneficial effects of the medication last and report this to your provider at the time of your next scheduled office visit. Although extremely uncommon, side effects may include agitation, fainting, seizures, cardiac arrhythmias or arrest during the infusion."