Quantification of Neural Activation in Spinal Cord by Blood Volume-Weighted FMRI on a Run-By-Run Basis a Viable Pain Assay for Analgesics Development

Fuqiang Zhao¹, Mangay Williams¹, Denise Welsh¹, Xiangjun Meng¹, Amy Ritter¹, Catherine Abbadie¹, Jacquelynn J. Cook¹, Alise S. Reicin¹, Richard Hargreaves¹, Donald S. Williams¹

Spinal cord fMRI offers an excellent opportunity to quantify nociception using neuronal activation induced by painful stimuli. Measurement of the magnitude of stimulation-induced activation, and its suppression with analgesics can provide objective measures of pain and efficacy of analgesics. In this study, a high sensitivity pain fMRI technique by combining BV-weighted fMRI with optimum electrical stimulus was developed. Its performance is demonstrated by measuring the effect of systemic lidocaine on noxious electrical stimulation-induced activation in spinal cord. The study also revealed that systemic lidocaine, which is clinically used for the treatment of neuropathic pain, and believed to only block the neural activity originating from the damaged peripheral nerves, also blocks noxious electrical stimulation-induced activity.