title: Associations between autonomic dysfunction and pain in chemotherapy-induced polyneuropathy.
abstract: BACKGROUND
  Autonomic neuropathy, a relatively common complication of several chemotherapy agents, can affect the vagus nerve and its pain inhibitory capacity, thus increasing sensitivity to pain. This study aimed to evaluate the relationships between autonomic parasympathetic function and the perception of (1) spontaneous pain; (2) experimental non-painful sensations; and (3) experimental painful sensations in chemotherapy-induced neuropathy patients.
  
  
  METHODS
  Twenty-seven cancer patients with chemotherapy-induced polyneuropathy were enrolled (20 women, age 56.6 ± 7.9). Autonomic parameters of heart rate variability, deep-breathing and Valsalva ratios, experimental non-painful parameters of warm, cold and mechanical detection thresholds, and painful parameters of heat pain thresholds, pain rating of suprathreshold stimulus, mechanical temporal summation and conditioned pain modulation response were examined.
  
  
  RESULTS
  Autonomic parameters and spontaneous pain levels were not associated, yet autonomic parameters were positively correlated with non-painful sensations - milder autonomic neuropathy was accompanied by milder sensory neuropathy as indicated by several parameters, e.g., lower Valsalva ratio was correlated with higher warmth detection threshold (r = -0.465; p = 0.033). Autonomic parameters were, however, negatively correlated with painful sensations - lower parasympathetic-vagal activity was associated with higher pain sensitivity as indicated by several parameters, e.g., lower Valsalva ratio was correlated with higher pain rating of suprathreshold stimulus (r = -0.559; p = 0.008).
  
  
  CONCLUSIONS
  Diminished vagal function due to neuropathy is associated with, and may possibly underlie, pain disinhibition expressed as greater levels of experimental pain.
authors.affiliation: The Laboratory of Clinical Neurophysiology, The Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel.
authors.forename: H
authors.initials: H
authors.lastname: Nahman-Averbuch
authors.forename: Y
authors.initials: Y
authors.lastname: Granovsky
authors.forename: E
authors.initials: E
authors.lastname: Sprecher
authors.forename: M
authors.initials: M
authors.lastname: Steiner
authors.forename: T
authors.initials: T
authors.lastname: Tzuk-Shina
authors.forename: D
authors.initials: D
authors.lastname: Pud
authors.forename: D
authors.initials: D
authors.lastname: Yarnitsky
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000009:adverse effects*; D001342:Autonomic Nervous System Diseases / Q000139:chemically induced* / Q000503:physiopathology; D003213:Conditioning, Psychological / Q000502:physiology; D003430:Cross-Sectional Studies; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000139:chemically induced* / Q000503:physiopathology; D010147:Pain Measurement / Q000187:drug effects; D017288:Pain Threshold / Q000187:drug effects; D010812:Physical Stimulation; D011115:Polyneuropathies / Q000139:chemically induced* / Q000503:physiopathology; D015656:Respiratory Mechanics; D012684:Sensory Thresholds / Q000187:drug effects; D014630:Vagus Nerve / Q000503:physiopathology; D014636:Valsalva Maneuver
chemical_list: D000970:Antineoplastic Agents