title: Painful stimulation and transient blocking of nerve transduction due to local anesthesia evoke perceptual distortions of the face in healthy volunteers.
abstract: Anecdotally, orofacial pain patients sometimes report that the painful face area feels "swollen." Because there are no clinical signs of swelling, such illusions may represent perceptual distortions. In this study, we examine whether nociceptive stimulation can lead to perceptual distortion of the face in a way similar to that of local anesthesia. Sixteen healthy participants received injections of .4 mL hypertonic saline to induce short-term nociceptive stimulation, .4 mL mepivacaine (local anesthetic) to transiently block nerve transduction, and .4 mL isotonic saline as a control condition. Injections were administered in both the infraorbital and the mental nerve regions. Perceptual distortions were conceptualized as perceived changes in magnitude of the injected areas and the lips, and they were measured using 1) a verbal subjective rating scale and 2) a warping procedure. Prior to the study, participants filled in several psychological questionnaires. This study shows that both nociceptive stimulation (P < .05) and transient blocking of nerve transduction (P < .05) can lead to perceptual distortion of the face. A test-retest experiment including 9 new healthy subjects supported the results. Perceptual distortions were positively correlated with the psychological variable of dissociation in several conditions (P < .05). Perceptual distortions may therefore be influenced by somatosensory changes and psychological mechanisms.
  
  
  CONCLUSIONS
  Knowledge of the factors that influence the perception of the face is important to understand the possible implications of perceptual distortions in orofacial pain disorders (and possibly other chronic pain states). Such information may ultimately open up new avenues of treatment for persistent orofacial pain.
authors: Department of Psychology and Behavioural Sciences, School of Business and Social Sciences, Aarhus University, Aarhus, Denmark; Section of Clinical Oral Physiology, Department of Dentistry, Aarhus University, Aarhus, Denmark. Electronic address: skyt@psy.au.dk.
authors: Ina
authors: I
authors: Skyt
authors: Section of Clinical Oral Physiology, Department of Dentistry, Aarhus University, Aarhus, Denmark; Scandinavian Center for Orofacial Neurosciences, Stockholm, Sweden.
authors: Lilja
authors: L
authors: Dagsdóttir
authors: Department of Psychology and Behavioural Sciences, School of Business and Social Sciences, Aarhus University, Aarhus, Denmark.
authors: Lene
authors: L
authors: Vase
authors: Section of Clinical Oral Physiology, Department of Dentistry, Aarhus University, Aarhus, Denmark; Scandinavian Center for Orofacial Neurosciences, Stockholm, Sweden.
authors: Lene
authors: L
authors: Baad-Hansen
authors: Section of Clinical Oral Physiology, Department of Dentistry, Aarhus University, Aarhus, Denmark; Scandinavian Center for Orofacial Neurosciences, Stockholm, Sweden.
authors: Eduardo
authors: E
authors: Castrillon
authors: Interacting Minds Center, Center for Functionally Integrative Neuroscience, Aarhus University, Aarhus, Denmark.
authors: Andreas
authors: A
authors: Roepstorff
authors: Danish Pain Research Center, Aarhus University Hospital, Aarhus, Denmark.
authors: Troels Staehelin
authors: TS
authors: Jensen
authors: Section of Clinical Oral Physiology, Department of Dentistry, Aarhus University, Aarhus, Denmark; Scandinavian Center for Orofacial Neurosciences, Stockholm, Sweden; Department of Dental Medicine, Karolinska Institute, Huddinge, Sweden.
authors: Peter
authors: P
authors: Svensson
mesh_terms: D000779:Anesthetics, Local / Q000494:pharmacology*; D005145:Face / Q000503:physiopathology; D005157:Facial Pain / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008340:Mandibular Nerve / Q000187:drug effects* / Q000503:physiopathology; D008442:Maxillary Nerve / Q000187:drug effects* / Q000503:physiopathology; D008619:Mepivacaine / Q000494:pharmacology*; D009407:Nerve Block; D059226:Nociceptive Pain / Q000503:physiopathology / Q000523:psychology; D010147:Pain Measurement; D058748:Pain Perception / Q000187:drug effects / Q000502:physiology; D010465:Perception / Q000187:drug effects / Q000502:physiology; D010468:Perceptual Disorders / Q000139:chemically induced / Q000503:physiopathology*; D015203:Reproducibility of Results; D012462:Saline Solution, Hypertonic; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D000779:Anesthetics, Local; D012462:Saline Solution, Hypertonic; D008619:Mepivacaine
keywords: Dissociation; local anesthesia; orofacial pain; painful stimulation; perceptual distortions of the face