title: Movement Evoked Pain and Mechanical Hyperalgesia after Intramuscular Injection of Nerve Growth Factor: A Model of Sustained Elbow Pain.
abstract: OBJECTIVE
  Lateral epicondylalgia presents as lateral elbow pain provoked by upper limb tasks. An experimental model of elbow pain provoked by movement/muscle contraction and maintained over several days is required to better understand the mechanisms underlying sustained elbow pain. This study investigated the time course and pain location induced by nerve growth factor (NGF) injection into a wrist extensor muscle, and whether movement and muscle contraction/stretch provoked pain.
  
  
  METHODS
  On Day 0 twenty-six painfree volunteers were injected with NGF (N = 13) or isotonic saline (randomized) into the extensor carpi radialis brevis (ECRB) muscle of the dominant arm. On Day 2 pain was induced in all participants by hypertonic saline injection into ECRB. A Likert scale and patient-rated tennis elbow evaluation (PRTEE) was used to assess pain and functional limitation (Days 0-10). Pain intensity during contraction/stretch of ECRB, and pressure pain thresholds (PPTs) were recorded before and after injections on Days 0 and 2, and Days 4 and 10.
  
  
  RESULTS
  Compared with isotonic saline, NGF evoked: i) greater Likert pain ratings from 12 hours post-injection until Day 6, ii) greater PRTEE scores on Days 2 and 4, iii) greater pain during ECRB contraction/stretch on Day 2, and iv) lower PPTs on Day 4.
  
  
  CONCLUSIONS
  This article presents a novel experimental human pain model suitable to study the sustained effects of lateral elbow pain on sensorimotor function and to probe the mechanisms underlying persistent musculoskeletal pain.
authors.affiliation: School of Health and Rehabilitation Sciences, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, Brisbane, Queensland, Australia.
authors.forename: Michael Joseph Gerard
authors.initials: MJ
authors.lastname: Bergin
authors.affiliation: Center for Neuroplasticity and Pain (CNAP), SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
authors.forename: Rogerio
authors.initials: R
authors.lastname: Hirata
authors.affiliation: Center for Neuroplasticity and Pain (CNAP), SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Mista
authors.affiliation: Center for Neuroplasticity and Pain (CNAP), SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
authors.forename: Steffan Wittrup
authors.initials: SW
authors.lastname: Christensen
authors.forename: Kylie
authors.initials: K
authors.lastname: Tucker
authors.affiliation: School of Health and Rehabilitation Sciences, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, Brisbane, Queensland, Australia.
authors.forename: Bill
authors.initials: B
authors.lastname: Vicenzino
authors.affiliation: School of Health and Rehabilitation Sciences, NHMRC Centre of Clinical Research Excellence in Spinal Pain, Injury and Health, Brisbane, Queensland, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Hodges
authors.affiliation: Center for Neuroplasticity and Pain (CNAP), SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark.
authors.forename: Thomas
authors.initials: T
authors.lastname: Graven-Nielsen
mesh_terms: D000293:Adolescent; D000328:Adult; D004550:Elbow / Q000601:surgery; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000175:diagnosis / Q000188:drug therapy*; D007273:Injections, Intramuscular / Q000379:methods; D008297:Male; D009068:Movement / Q000187:drug effects; D063806:Myalgia / Q000188:drug therapy; D020932:Nerve Growth Factor / Q000008:administration & dosage / Q000627:therapeutic use*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology; D013716:Tennis Elbow / Q000188:drug therapy; D055815:Young Adult
chemical_list: C502240:NGF protein, human; D020932:Nerve Growth Factor
keywords: Elbow Pain; Hyperalgesia; Muscle Contraction; Muscle Stretch; Nerve Growth Factor