Noxious radiant heat evokes bi-component nociceptive withdrawal reflexes in spinal cord injured humans—A clinical tool to study neuroplastic changes of spinal neural circuits

Frontiers in Human Neuroscience

Neuroscience

Anke Tappe-Theodor¹  Rolf-Detlef Treede²  Sigrid Schuh-Hofer³  Norbert Weidner⁴  Steffen Franz⁴  Laura Heutehaus⁴ 

[1] Department of Molecular Pharmacology, Medical Faculty Heidelberg, Institute of Pharmacology, Heidelberg University, Heidelberg, Germany;Department of Neurophysiology, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, Ruprecht-Karls-University of Heidelberg, Mannheim, Germany;Department of Neurophysiology, Mannheim Center for Translational Neuroscience, Medical Faculty Mannheim, Ruprecht-Karls-University of Heidelberg, Mannheim, Germany;Department of Neurology and Epileptology, University of Tübingen, Tübingen, Germany;Spinal Cord Injury Center, Heidelberg University Hospital, Heidelberg, Germany;

关键词: spinal cord injury;    neuroplastic changes;    neuropathic pain;    spasticity;    hyperexcitability;    maladaptive plasticity;    withdrawal reflexes;   

DOI  :  10.3389/fnhum.2023.1141690

 received in 2023-02-07, accepted in 2023-04-04,  发布年份 2023

来源: Frontiers

【 摘 要 】

Investigating nocifensive withdrawal reflexes as potential surrogate marker for the spinal excitation level may widen the understanding of maladaptive nociceptive processing after spinal cord injury (SCI). The aim of this prospective, explorative cross-sectional observational study was to investigate the response behavior of individuals with SCI to noxious radiant heat (laser) stimuli and to assess its relation to spasticity and neuropathic pain, two clinical consequences of spinal hyperexcitability/spinal disinhibition. Laser stimuli were applied at the sole and dorsum of the foot and below the fibula head. Corresponding reflexes were electromyography (EMG) recorded ipsilateral. Motor responses to laser stimuli were analyzed and related to clinical readouts (severity of injury/spasticity/pain), using established clinical assessment tools. Twenty-seven participants, 15 with SCI (age 18–63; 6.5 years post-injury; AIS-A through D) and 12 non-disabled controls, [non-disabled controls (NDC); age 19–63] were included. The percentage of individuals with SCI responding to stimuli (70–77%; p < 0.001), their response rates (16–21%; p < 0.05) and their reflex magnitude (p < 0.05) were significantly higher compared to NDC. SCI-related reflexes clustered in two time-windows, indicating involvement of both A-delta- and C-fibers. Spasticity was associated with facilitated reflexes in SCI (Kendall-tau-b p ≤ 0.05) and inversely associated with the occurrence/severity of neuropathic pain (Fisher’s exact p < 0.05; Eta-coefficient p < 0.05). However, neuropathic pain was not related to reflex behavior. Altogether, we found a bi-component motor hyperresponsiveness of SCI to noxious heat, which correlated with spasticity, but not neuropathic pain. Laser-evoked withdrawal reflexes may become a suitable outcome parameter to explore maladaptive spinal circuitries in SCI and to assess the effect of targeted treatment strategies. Registration: https://drks.de/search/de/trial/DRKS00006779.

【 授权许可】

Unknown   
Copyright © 2023 Franz, Heutehaus, Tappe-Theodor, Weidner, Treede and Schuh-Hofer.