Impact of Peripheral Afferent Input on Central Neuropathic Pain

The overarching aim of this study is to investigate the contribution of peripheral afferent input to spontaneous and evoked central neuropathic pain after a spinal cord lesion or disease.

Inclusion Criteria:Definite central neuropathic pain according to current diagnostic algorithms involving at least both feet or both hands bilaterally and symmetrically with regard to the expected neuroanatomical distribution of the nerve block.Patients with spinal cord injury. For patients with pain in both legs, the injury has to be incomplete. For patients with pain in both arms, the injury can be complete or incomplete. The pain in the area that will be investigated (region of interest) has to be in an area with at least some preservation of sensationAn intensity of spontaneous pain of ≥4 NRS [0-10] in the region of interest during the screening visit and at the day of the intervention.Participant is able and willing to give informed consent.For female subjects of childbearing potential: A negative pregnancy test and either use of highly effective contraception or sexual abstinenceExclusion Criteria:Conus/cauda involvement or evidence of peripheral neuropathic pain due to documented peripheral lesion.Other known neurological and psychiatric conditionsHistory or symptoms of significant diseases that may confound the measurements or represent contra-indications for the intervention (e.g., neuropathy following cancer or metabolic diseases such as diabetes mellitus, liver diseases, and kidney diseases.Cardiovascular diseases that preclude the anaesthetic intervention (e.g., arrythmias).Concomitant nociceptive pain within the innervation territory of the planned nerve block.Unable to understand and speak DanishChanges in pain medication within the last 4 weeks prior to the intervention.Treatment with warfarin or other blood thinning medications, that contraindicates regional anesthesia if the treating physician cannot recommend that such treatments are paused for at least 7 days before the study dayInfection or skin disease in planned injection areaAllergy for local anestheticsPregnancy or lactation.Alcohol or drug abusePain intensity below 4 in the region of interest at the baseline measurement before the nerve block