The Effect of Outpatient Ketamine Infusion on Chronic Neuropathic Pain and PTSD

Subjects will be recruited with no target toward ethnicity, gender, or race. Active duty, veteran, retiree, and military dependents between the ages of 18-70 years old with an established diagnosis of chronic neuropathic pain will be identified and screened for study inclusion. Enrollees will have had neuropathic pain \>3 months duration, report a pain score between 4-7, and meet inclusion/exclusion criteria for the study. Since ketamine's influence on PTSD is a secondary measure, any patients with a PCL-5 score \> 33 will be noted. After informed consent is obtained participants will be randomized into a (1) moderate dose ketamine, (2) moderate dose ketamine +Mg, or (3) a magnesium control group. The magnesium-only group will be randomly assigned to one of the treatment groups (moderate dose ketamine or moderate dose ketamine +Mg) after 2 weeks and complete the full infusion treatment regime of the randomly selected treatment group. Administration of ketamine will occur in diminishing number of dosing events: Week 1 \& 2 will consist of 3 treatments per week. Weeks 3 \& 4 will consist of 2 treatments per week. Weeks 5 \& 6 will consist of 1 treatment per week. Booster treatments will be administered week 10 and week 24. Booster treatments will only be 1 infusion that week. Participants will fill out questionnaires before and after each infusion- day concerning their pain, PTSD, anxiety, depression, and quality of life. Participants will be evaluated at least 5 days prior to the first treatment and 30-35 days after the final infusion. Participants will continue their current pain management regimen during the study and be instructed to use analgesics only as needed. Pain medication use will be recorded throughout the study.