Immersing the foot in painfully-cold water evokes ipsilateral extracranial vasodilatation

Abstract

Temporal pulse amplitude was recorded bilaterally in 56 participants before, during and after three ice-water immersions of the foot. Half of the participants were told that prolonged exposure to freezing temperatures could cause frostbite. Increases in pulse amplitude were greater in the ipsilateral than contralateral temple during and after the three foot-immersions.Although pulse amplitude decreased after threatening instructions and repeated immersion of the foot, the vasodilator response persisted during all three immersions. These findings suggest that nociceptive stimulation of the foot evokes an ipsilateral supra-spinal extracranial vasodilator response, possibly as part of a broader defense response. AbstractKey words: extracranial vasodilatation; nociceptive reflex; fear; cold pressor test; sympathetic nervous system 3

A Human Sensory Pathway Connecting the Foot to Ipsilateral Face That Partially Bypasses the Spinal Cord

“…Yet, similar studies on spinal cord injury by Donati et al (2016) and Wrigley et al (2018) have also drawn conclusions based upon small patient numbers, and our results did achieve statistical significance. In addition to repeating this work on larger numbers, there are several other techniques for facial blood flow measurement that could be implemented in future efforts to verify our findings, including LDI (Hoeksema et al, 2014), photoplethysmography (Drummond and Chung, 2012), and thermography (Shearn et al, 1990). Finally, we note that our choice of pharmacologic agent for cutaneous C-fiber blockade, capsaicin, is not completely ideal, given that it induces delayed central sensitization (O'Neill et al, 2012), but lidocaine is also not ideal as we note in our Results, and none of our participants were symptomatic until well after completion of data collection.…”

“…Parasympathetic fibers cross over in the brainstem (Lambert et al, 1984), and in the rat (Suzuki and Hardebo, 1991), cat (Akiyama and Yamazaki, 2001), and presumably human—each sphenopalatine ganglion results in bilateral innervation. While we previously proposed a supraspinal mechanism as a possible explanation for ipsilateral extracranial vasodilatation (Drummond and Chung, 2012), we discount this as all of our spinal-cord injured patients had eyes covered during the experiment, and none could identify which side was immersed when asked.…”

“…To determine whether nociceptive information can bypass an interrupted spinal cord, we conducted our previously verified painfully-cold water foot immersion test (Drummond and Chung, 2012) in 10 patients with clinical and imaging confirmation of recent traumatic complete spinal cord injury and compared the results with those of an identical test performed on 10 healthy volunteers. One foot of each participant was immersed in painfully-cold water for a total of 3 min within a 15-min session of data acquisition, with facial blood flow measured by laser Doppler flowmetry (Rajan et al, 2009).…”

“…There is also recent functional MRI evidence indicating that somatosensory neural transmission can bypass a complete spinal cord injury, but the exact pathway was not determined (Wrigley et al, 2018). Additionally, there are descriptions of sensory phenomena suggesting proximal propagation of afferent neural information in humans ipsilateral to the side of peripheral stimulation, such as extracranial vasodilatation following painful foot immersion (Drummond and Chung, 2012) and referred itch (Richter, 1977), but the nature of such pathways has yet to be elucidated. We speculated that a common neural pathway responsible for 3 phenomena—ascending pain transmission following cordotomy and complete spinal cord injury, ipsilateral extracranial vasodilatation following painful foot immersion, and referred itch—is located in the skin, partially bypassing the spinal cord, in a manner similar to antidromic and orthodromic conduction in neurogenic inflammation, partially bypassing the spinal cord (Chahl, 1988).…”

A correlational analysis of human cognitive activity using Infrared Thermography of the supraorbital region, frontal EEG and self-report of core affective state.

“…For example, it has been proposed that cortical control and representation of autonomic function is asymmetrical and that this autonomic opponency is the foundation of feelings of core affective state [19,20]. Functional asymmetry of the sympathetic nervous system has also been demonstrated in studies of facial blood flow using pulse transducers [52,53]. In one of the few examples of medical research into facial temperature asymmetry, using thermistor sensors, significantly higher right blood flow and temperature in the forehead (but not in the cheeks) has been attributed to hemispheric asymmetry of sympathetic vascular control [54].…”