Neuropathic or nerve injury related pain (NP), an extremely unpleasant condition that is
difficult to treat, often has a severe, persistent, and unremitting course. Conventional
treatments are often ineffective in relieving NP. Recently, the investigators have developed
a cost-efficient regimen involving use of low dose infusions of ketamine for treating
neuropathic pain in patients in whom oral medications have failed. We have observed excellent
benefits in many of these patients. However, this treatment requires titration and monitoring
during the infusion and currently it is not possible to predict which patients will benefit
from this intervention. The investigators have shown that functional magnetic resonance
imaging (fMRI) of the brain can be used as a tool to predict relief of pain and to assess the
effect of treatment in some chronic pain conditions. This innovative project involves
development of an fMRI-guided treatment with intravenous ketamine in patients with NP. This
study aims to analyze patterns of changes in fMRI of the brain, before and after infusion of
ketamine and to correlate the changes with pain intensity. The information from this study
will help to deliver this therapy earlier to those patients who are most likely to benefit
from ketamine.