Reliable estimation of nociceptive withdrawal reflex thresholds

Area of Science:

• Neuroscience
• Pain Research
• Clinical Assessment

Background:

• The nociceptive withdrawal reflex (NWR) assesses spinal nociceptive circuitry excitability.
• Current NWR threshold (NWR-T) estimation often uses sural nerve stimulation, causing pain and hindering completion.

Purpose of the Study:

• To compare the failure rates and test-retest reliability of NWR-T estimation using sural nerve stimulation versus foot arch stimulation.
• To introduce a more feasible and reliable method for NWR-T assessment.

Main Methods:

• NWR-Ts were estimated using a fully-automated interleaved up-down staircase procedure.
• Electrical stimulation was applied to the sural nerve and the arch of the foot.
• NWRs were detected via EMG of the biceps femoris and tibialis anterior muscles.
• Test-retest reliability was assessed over two sessions using Bland-Altman analysis.

Main Results:

• Foot arch stimulation had a significantly lower failure rate (5%) compared to sural nerve stimulation (29%).
• Both methods showed similar within-session reliability.
• Foot arch stimulation demonstrated superior between-session reliability.

Conclusions:

• Stimulation at the arch of the foot offers a more reliable and less failure-prone method for NWR-T estimation.
• This finding supports a shift towards using foot arch stimulation for NWR-T assessments.
• The improved reliability enhances the clinical utility of NWR assessments.