title: A Comparison of the Sensitivity of Brush Allodynia and Semmes-Weinstein Monofilament Testing in the Detection of Allodynia Within Regions of Secondary Hyperalgesia in Humans.
abstract: Two of the most common Quantitative Sensory Techniques (QST) employed to detect allodynia include mechanical brush allodynia and Semmes-Weinstein monofilaments. However, their relative sensitivity at detecting allodynia is poorly understood. The purpose of this study was to compare the sensitivity of brush allodynia against Semmes-Weinstein monofilament technique for detecting allodynia within regions of secondary hyperalgesia in humans.
  
  
  
  Twenty subjects (10 males, 10 females; 21.1 ± 0.9 years) were recruited and randomly allocated to allodynia or monofilament groups. Topical capsaicin (Zostrix 0.075%) was applied to a target region defined by C4-C7 dermatomes. Allodynia testing was performed at 0- (baseline) and 10 minutes postcapsaicin. The Semmes-Weinstein group assessed changes in skin sensitivity 8 cm inferior to target region and 2 cm lateral to the spinous process, while brush allodynia was employed to detect the point inferior to the target region where subjects reported changes in skin sensitivity. The distance (cm) from this point to the inferior border of the target region was termed the Allodynia Score.
  
  
  
  Statistically significant increases in the Allodynia Score were observed at 10 minutes postcapsaicin compared to baseline (P < 0.001). No differences in monofilament scores were observed between 10 minutes postcapsaicin and baseline (P = 0.125). Brush allodynia also demonstrated superior sensitivity, detecting allodynia in 100% of cases compared to 60% in the Semmes-Weinstein group.
  
  
  
  Brush allodynia is more sensitive than Semmes-Weinstein monofilaments for detecting mechanical allodynia in regions of secondary hyperalgesia. Brush allodynia may be preferred over Semmes-Weinstein monofilaments for clinical applications requiring reliable detection of allodynia.
authors.affiliation: Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Emmalee C
authors.initials: EC
authors.lastname: Maracle
authors.affiliation: Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Laurie Y
authors.initials: LY
authors.lastname: Hung
authors.affiliation: Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Sabrina I
authors.initials: SI
authors.lastname: Fell
authors.affiliation: Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Osmond
authors.affiliation: Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
authors.forename: Stephen H M
authors.initials: SH
authors.lastname: Brown
authors.affiliation: Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.
authors.forename: John Z
authors.identifier: 0000-0002-7455-8811
authors.initials: JZ
authors.lastname: Srbely
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000175:diagnosis*; D008297:Male; D010147:Pain Measurement / Q000379:methods*; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: Semmes-Weinstein monofilaments; allodynia; analgesia testing; assessment; brush allodynia; capsaicin-induced; central sensitization; experimental pain; human model; pain; secondary hyperalgesia; sensitivity