Are changes in nociceptive withdrawal reflex magnitude a viable central sensitization proxy? Implications of a replication attempt. (January 2023)

• Record Type: Journal Article
• Authors: Guekos, A.; Grata, A.C.; Hubli, M.; Schubert, M.; Schweinhardt, P.
• Is Part Of: Clinical neurophysiology. Volume 145(2023)
• Page Start: 139
• Page End: 150
• Publication Date: 2023-01
• Subjects: Nociceptive withdrawal reflex -- Central sensitization -- Response rate -- Reliability; Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2022.09.011
• Languages: English
• ISSNs: 1388-2457

Abstract

Highlights: A previously observed increase in nociceptive withdrawal reflex (NWR) magnitude during application of painful heat was not replicated. Strong parameter sensitivity in central sensitization and NWR studies warrants precise reporting of study methods to guarantee replicability. Stimulating the medial plantar nerve and recording from the tibialis anterior muscle yielded response rates of up to 79% for repetitive suprathreshold stimulations. Abstract: Objective: The nociceptive withdrawal reflex (NWR) has been proposed to read-out central sensitization (CS). Replicating a published study, it was assessed if the NWR magnitude reflects sensitization by painful heat. Additionally, NWR response rates were compared for two stimulation, the sural nerve at the lateral malleolus (SU) and the medial plantar nerve on the foot sole (MP), and three recording sites, biceps femoris (BF), rectus femoris (RF), and tibialis anterior (TA) muscles. Methods: 16 subjects underwent one experiment with six blocks of eight transcutaneous electrical stimulations to elicit the NWR while surface electromyography was collected. Tonic heat was concurrently applied in the same dermatome. Temperatures rose from 32 °C in the first to 46 °C in the last block following the previously published protocol. Results: Tonic heat did not influence NWR magnitude. The highest NWR response rate was obtained for MP–TA combination (79%). Regarding elicitation in all three muscles, SU stimulation outperformed MP (59% vs 57%). Conclusions: The replication failed. NWR magnitude as a CS proxy in healthy subjects needs continued investigation. With respect to response rates, MP–TA proved efficient, whereas SU stimulation seemed preferable for multiple muscle recordings. Significance: Unclear methodological descriptions in the original study affected CS and NWR replication. The NWR magnitude changes induced by CS may closely depend on the different stimulation methods used.