title: Pressure algometry with a rotational fanning probe improves the detection of experimental muscle hyperalgesia.
abstract: OBJECTIVE
  Muscle hyperalgesia is typically evaluated by pressure algometry applying linear stimulation. Combining linear pressure stimulation with additional minor variations of the pressure in different directions may optimize the detection of pain sensitivity in hyperalgesic muscle.
  
  
  METHODS
  Pressure pain thresholds (PPTs) to linear pressure stimulations were assessed on the extensor carpi radialis brevis (ECRB) muscle in 18 healthy subjects with a computer-controlled pressure algometer. During constant pressure stimulation (5 seconds) equal to the PPT, rotational (45 to 180°), linear vibrational (15 to 50 Hz), or radial vibrational (5 to 25 Hz) stimulations were applied via regular and fanning rounded probes (1 cm2). The pressure pain intensity was rated on an electronic visual analogue scale (VAS). Muscle hyperalgesia was induced in nine subjects by injections of nerve growth factor (NGF) into the ECRB muscle, and isotonic saline was injected as a control condition in other nine subjects on day 0. The PPT and related pressure pain sensitivity were assessed on day -1, day +1, and day +4.
  
  
  RESULTS
  The PPT at day +1 was decreased in the NGF group compared with day -1 and the controls (P < 0.01). Preinjection (day -1) analysis showed that VAS scores were increased for rotation compared with linear stimulation alone (P < 0.001). During NGF-induced muscle, hyperalgesia linear pressure stimulation with rotation of the fanning probe induced higher VAS scores than with the regular probe within the NGF group as well as between NGF and control groups (P < 0.02).
  
  
  CONCLUSIONS
  Rotational stimulation together with pressure stimulation was more efficient than classical pressure algometry in detecting muscle hyperalgesia.
authors.affiliation: Laboratory for Musculoskeletal Pain and Motor Control, Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
authors.forename: Djordje
authors.initials: D
authors.lastname: Adnadjevic
authors.forename: Thomas
authors.initials: T
authors.lastname: Graven-Nielsen
mesh_terms: D000328:Adult; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000139:chemically induced / Q000175:diagnosis*; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000473:pathology*; D063806:Myalgia / Q000139:chemically induced / Q000175:diagnosis*; D020932:Nerve Growth Factor / Q000633:toxicity; D010147:Pain Measurement / Q000295:instrumentation* / Q000379:methods*; D010812:Physical Stimulation / Q000379:methods; D011312:Pressure
chemical_list: D020932:Nerve Growth Factor
keywords: Hyperalgesia; Muscle Stimulation; Pressure Algometry