A patient accidentally exposed to oven microwaves developed an acute and severe dystrophy and sympathetic reflex of the right hand, a peripheral neuropathy of the digits of the left hand, and a sensory injury of the trigeminal nerve in the right side of the face. The physiopathological involvement in the injury of the peripheral nerve and the failure of analgesia with carbamazepine are emphasized. In this causalgia, relief from pain and modification of the autonomic disorders can be achieved by a sympathetic block.