Abstract: Chronic neuropathic pain is a common cause of disability in the population. Most treatment options for patients with medically refractory neuropathic pain, such as spinal cord stimulation, thalamic deep brain stimulation or intrathecal infusion of narcotics, are aimed at producing analgesia and are known to have limited efficacy. We propose an innovative neuromodulation-based approach to treat patients with central thalamic pain syndrome, a particularly severe form of neuropathic pain characterized by relentless anesthesia dolorosa resulting from injury to the thalamic sensory pathways. We depart from the traditional goal of intervening in the sensory discriminative neural pathways of pain transmission in order to produce analgesia. Instead, we plan to target with deep brain stimulation (DBS) the ventral area of the anterior limb of the internal capsule (ALIC), a region densely populated by fibers related to neural networks related to the control of behavior and emotion. By electrically stimulating these networks, we expect to modulate the affective sphere of patients with otherwise intractable pain and, consequently, reduce pain related disability. We hypothesize that the improvement in pain related disability associated with modulation of the affective pain sphere will not be dependent on analgesic effects. For this reason, the visual analog scale will be used as a secondary outcome measure to control for pain levels and analgesia but the primary outcome measure of the study will be the pain disability index. Patients enrolled in this research will undergo baseline and post-DBS double blinded evaluations for a period of six months, followed by chronic open label stimulation. The neural circuits of emotion control and the effects of DBS upon these networks will be studied at regular intervals with functional magnetic resonance imaging and magnetoencephalography. Public Health Relevance: Chronic neuropathic pain is very common in the population, affecting 8% of individuals enrolled in family practices. It is a leading cause of disability in the United States and other countries. Although several treatment options exist, large shares of patients with chronic pain (up to 50%) fail to respond and remain disabled. In this proposal, we describe an innovative approach to alleviate suffering and disability among those with severe and refractory chronic neuropathic pain.
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