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Silberstein M, Nunn AK, Drummond PD, Wan DWL, Alexander J, Millard M, Galea MP. A Human Sensory Pathway Connecting the Foot to Ipsilateral Face That Partially Bypasses the Spinal Cord. Front Neurosci 2019; 13:519. [PMID: 31191224 PMCID: PMC6539214 DOI: 10.3389/fnins.2019.00519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 05/06/2019] [Indexed: 11/13/2022] Open
Abstract
Human sensory transmission from limbs to brain crosses and ascends through the spinal cord. Yet, descriptions exist of ipsilateral sensory transmission as well as transmission after spinal cord transection. To elucidate a novel ipsilateral cutaneous pathway, we measured facial perfusion following painfully-cold water foot immersion in 10 complete spinal cord-injured patients, 10 healthy humans before and after lower thigh capsaicin C-fiber cutaneous conduction blockade, and 10 warm-immersed healthy participants. As in healthy volunteers, ipsilateral facial perfusion in spinal cord injured patients increased significantly. Capsaicin resulted in contralateral increase in perfusion, but only following cold immersion and not in 2 spinal cord-injured patients who underwent capsaicin administration. Supported by skin biopsy results from a healthy participant, we speculate that the pathway involves peripheral C-fiber cross-talk, partially bypassing the cord. This might also explain referred itch and jogger's migraine and it is possible that it may be amenable to training spinal-injured patients to recognize lower limb sensory stimuli.
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Affiliation(s)
- Morry Silberstein
- School of Molecular and Life Sciences, Curtin University, Perth, WA, Australia
- Victorian Spinal Cord Service, Austin Health, Melbourne, VIC, Australia
- *Correspondence: Morry Silberstein
| | - Andrew K. Nunn
- Victorian Spinal Cord Service, Austin Health, Melbourne, VIC, Australia
| | | | - Dawn Wong Lit Wan
- School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| | - Janette Alexander
- Victorian Spinal Cord Service, Austin Health, Melbourne, VIC, Australia
| | - Melinda Millard
- Victorian Spinal Cord Service, Austin Health, Melbourne, VIC, Australia
| | - Mary P. Galea
- Victorian Spinal Cord Service, Austin Health, Melbourne, VIC, Australia
- Department of Medicine, University of Melbourne, Melbourne, VIC, Australia
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