title: Reliability and validity of a brief method to assess nociceptive flexion reflex (NFR) threshold.
abstract: The nociceptive flexion reflex (NFR) is a physiological tool to study spinal nociception. However, NFR assessment can take several minutes and expose participants to repeated suprathreshold stimulations. The 4 studies reported here assessed the reliability and validity of a brief method to assess NFR threshold that uses a single ascending series of stimulations (Peak 1 NFR), by comparing it to a well-validated method that uses 3 ascending/descending staircases of stimulations (Staircase NFR). Correlations between the NFR definitions were high, were on par with test-retest correlations of Staircase NFR, and were not affected by participant sex or chronic pain status. Results also indicated the test-retest reliabilities for the 2 definitions were similar. Using larger stimulus increments (4 mAs) to assess Peak 1 NFR tended to result in higher NFR threshold estimates than using the Staircase NFR definition, whereas smaller stimulus increments (2 mAs) tended to result in lower NFR threshold estimates than the Staircase NFR definition. Neither NFR definition was correlated with anxiety, pain catastrophizing, or anxiety sensitivity. In sum, a single ascending series of electrical stimulations results in a reliable and valid estimate of NFR threshold. However, caution may be warranted when comparing NFR thresholds across studies that differ in the ascending stimulus increments.
  
  
  CONCLUSIONS
  This brief method to assess NFR threshold is reliable and valid; therefore, it should be useful to clinical pain researchers interested in quickly assessing inter- and intra-individual differences in spinal nociceptive processes.
authors.affiliation: Department of Psychology, The University of Tulsa, Tulsa, Oklahoma 74104, USA. jamie-rhudy@utulsa.edu
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Rhudy
authors.forename: Christopher R
authors.initials: CR
authors.lastname: France
mesh_terms: D000293:Adolescent; D004311:Double-Blind Method; D004558:Electric Stimulation / Q000009:adverse effects; D004576:Electromyography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009271:Naltrexone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010146:Pain / Q000503:physiopathology* / Q000523:psychology; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology*; D011569:Psychiatric Status Rating Scales; D012018:Reflex / Q000502:physiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012737:Sex Factors; D012867:Skin / Q000294:innervation; D013223:Statistics as Topic; D013497:Sural Nerve / Q000502:physiology; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D009292:Narcotic Antagonists; D009271:Naltrexone