Our goals for this study involve using intravenous lidocaine as it is normally used in the Stanford Pain Management Center to assess the effect of intravenous lidocaine on chronic pain. Studies have been done determining the efficacy of intravenous lidocaine for treating pain but little research has been done to determine the effects of an intravenous lidocaine infusion on the different components of the pain experience. Our study will incorporate pain quality measures both before and during the infusions of lidocaine to determine changes in present pain intensity.

Each patient will receive an intravenous infusion of lidocaine. Drug will be infused using a computer-controlled paradigm. This paradigm allows increasing plasma concentrations in a step-wise manner, keeping the concentration during each infusion step constant. Plasma concentrations will be increased gradually from 0 to 5 ug/ml in a method at the discretion of the medical team. This will be conducted according to standard medical practice for the infusion and the study procedures will not affect the infusion paradigm. Total infusion time is approximately 1-2 hours. During the course of the study, the primary outcome measure was changed from blood oxygenation level dependent (BOLD) signal to pain intensity.

Inclusion Criteria:- subjects between the ages of 18 and 100 years for clinical component; subjects between the ages of 18 and 70 for the MRI component

• meets the study criteria of chronic pain of either peripheral or central origin
• male or a non-pregnant, non-lactating female. If females are of reproductive potential (i.e., not surgically sterilized and/or not post menopausal), they must be practicing an accepted method of birth control, agree to a urine pregnancy test at the start of each study session (for patient scheduled through the clinic, this has already been addressed by the recommending physician)
• is not currently on a sodium channel blocking agent, anticonvulsant, or tricyclic antidepressant,
• must be able to comply with any other study requirements and complete experimental tasks
• have no reported substance abuse within the past six months; Exclusion Criteria:- subject is lactating or pregnant;
• subject suffers from clinically significant cardiac, pulmonary, renal or liver disease;
• subject allergic to lidocaine.
• MRI Component: any metal objects (especially surgical clips), devices, or implants or any other MRI contraindication

Seventy-one patients with chronic neuropathic pain

Adverse event data were collected during the infusion period (approximately one hour) for each participant.

The definitions for adverse event and serious adverse event did not differ from clinicaltrials.gov.