What Is Iv(3)in Curing Neuropathy?

my husband, who is 80, has been diagnosed with neuropathies in his legs which is limiting his ability to walk. (No feeling in his legs from the knee down). Doc suggested getting a treatment by IV (3) that is supposed to help his neuropathy. Any idea what that is. Didn t get be with him at the docs office last time when this was talked about.