Advancement of Psychophysics of Pain Modulation From Lab to Clinic: Constructing Susceptibility Profile for Appearance of Postoperative Neuropathic Pain
Condition: Pain, Postoperative
MeSH terms: Neuralgia; Pain, Postoperative
Study type: Observational

Summary: 
      Recent advances in the field of pain psychophysics that have enhanced the understanding of
      pain processing by the nervous system seem to characterize the individual pattern of pain
      processing, thereby enabling the prediction of a person's susceptibility to develop chronic
      pain consequent to surgery.

      In this project, the researchers propose to apply a wide array of advanced testing methods in
      order to prospectively assess the pain modulation pattern of pain free patients about to
      undergo an elective thoracotomy. Since about half of post-thoracotomy patients suffer from
      chronic neuropathic postoperative pain, the researchers expect to identify which tests
      predict a risk for this pain and the relative power of the relevant tests in this prediction,
      and to construct a short and applicable tool, the 'pain susceptibility profile', that will
      reliably predict the risk for the development of pain. The expected results of this project
      will serve the field of pain prevention by identifying patients at risk and tailoring
      interventions to reduce the risk of chronic pain.
    

Detailed description: 
      The common prevalence of painful syndromes following surgical interventions and injuries
      calls for a preventive therapeutic approach that can only be based on better insight into the
      pain modulation mechanisms in these patients. Recent advances in the field of pain
      psychophysics that have enhanced our understanding of pain processing by the nervous system
      seem to characterize the individual pattern of pain processing, thereby enabling the
      prediction of a person's susceptibility to develop chronic pain consequent to surgery.

      In this project, we propose to apply a wide array of advanced testing methods in order to
      prospectively assess the pain modulation pattern of pain free patients about to undergo an
      elective thoracotomy. Tests will include:

        1. psychophysical tests: pain thresholds and suprathreshold magnitude estimation, temporal
           summation, endogenous analgesia - diffuse noxious inhibitory control (DNIC);

        2. tests for the interaction between pain and the autonomic nervous system including the
           inhibitory effect of vagal activation on pain perception, and the response pattern of
           the sympatho-parasympathetic balance to noxious stimulation; and

        3. evaluation of personality components known to be associated with chronic pain including
           anxiety, catastrophization and somatization.

      Since about half of post-thoracotomy patients suffer from chronic neuropathic postoperative
      pain, we expect to identify which tests predict a risk for this pain and the relative power
      of the relevant tests in this prediction, and to construct a short and applicable tool, the
      'pain susceptibility profile', that will reliably predict the risk for the development of
      pain. The contribution of the above tests to the severity of acute postoperative pain, and of
      the latter on the development of the chronic postoperative pain will also be evaluated.

      The expected results of this project will serve pain prevention by identifying patients at
      risk and tailoring interventions to reduce the risk of chronic pain. Also, in the wider pain
      research context, this understanding will allow better design and analysis of studies on pain
      mechanisms and therapies by considering the pain susceptibility of participating patients.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Inclusion Criteria:

          -  Pain free patients to undergo major thoracic operation with both malignant and
             non-malignant diseases.

        Exclusion Criteria:

          -  Psychiatric or cognitive dysfunction precluding use of psychophysics

          -  Existing thoracic pain

          -  Patients who cannot communicate in Hebrew
      
Keywords: thoracotomy; post-operative pain; chronic pain; endogenous analgesia; temporal summation; central sensitization; prediction; Patients Who Should Undergo Thoracotomy