Delineating Areas of Secondary Hyperalgesia: Influence of the Assessment Method
Condition: Measurements of Areas of Secondary Hyperalgesia
MeSH terms: Neoplasm Metastasis; Hyperalgesia
Study type: Observational

Summary: 
      Assessments of mechanical skin sensitivity include psychophysical responses to stimulation
      with calibrated polyamide monofilaments.

      One of the applications of polyamide monofilaments are the assessments of magnitude of
      secondary hyperalgesia areas (SHAs), i.e. areas in normal skin near an injury with increased
      mechanical sensitivity.

      The objective of the study is to investigate the hypothesis, based on previous studies, that
      a light tactile stimulus delineates a larger SHA than stimulation with a more rigid
      monofilament.

      Twenty-three healthy participants were included in this randomized, two-observer, test-retest
      study.

      A highly significant positive correlation between the bending force of the polyamide
      filaments and the magnitude of SHA was demonstrated. The "weighted-pin" instrument showed
      significantly and consistently larger areas than the polyamide monofilaments.

      The hypothesis was rejected: a light tactile stimulus did not delineate a larger secondary
      hyperalgesia area than stimulation with a more rigid monofilament. The "weighted-pin"
      instrument seems an alternative to the conventional polyamide monofilaments.
    

Detailed description: 
      Introduction Assessments of mechanical skin sensitivity include psychophysical responses to
      stimulation with calibrated polyamide monofilaments. Although the theoretical background and
      the application of monofilaments are straightforward, inconsistencies of the method have been
      reported in the literature. One of the applications of polyamide monofilaments are the
      assessments of magnitude of secondary hyperalgesia areas (SHAs), i.e. areas in normal skin
      near an injury with increased mechanical sensitivity. Secondary hyperalgesia is a measure of
      central sensitization and reflects the effect of an injury on the central nervous system. The
      objective of the study is to investigate the hypothesis, based on previous studies, that a
      light tactile stimulus delineates a larger SHA than stimulation with a more rigid
      monofilament.

      Method Twenty-three healthy participants were included in this randomized, two-observer,
      test-retest study. The volunteers were blinded to the test-results. The design was adjusted
      to examine intra-/inter-observer and intra-/inter-day variability in SHAs after a first
      degree burn injury was induced by a contact thermode (47ºC, 7 minutes, thermode area 12.5
      cm2) on the lower leg. The SHAs were assessed 45 to 75 min (15 min for each observer) after
      the burn injury and delineated by 3 different polyamide monofilaments (50, 299, 986 mN) and a
      "weighted-pin" instrument (512 mN). The testing order of the monofilaments was randomized,
      and the observers were blinded to the study results of each other. The examination order of
      the observers on Day 1 was reversed on Day 2 (> 6 weeks later).
    

Sampling method: Probability Sample
Study population: 
        Healthy participants
      
Keywords: Secondary Hyperalgesia; Method; Pin-prick; Monofilament