AREAS OF RESEARCH ACTIVITY

1) Perioperative nociception and pain

Our research emphasis in this area is on diagnosing and quantifying perioperative nociceptive inputs due to surgery and their consequences in the acute postoperative period (up to 1 week postoperatively). The insight derived from this research offers a basis for more rational mechanism-based anaesthetic and analgesic management of the surgical patient, and forms the basis for the prevention of subsequent pain chronification (cf. below). more...

Main ongoing projects:

• Documenting pain and analgesic management on the PACU as the basis of a quality management system
• Hyperalgesia on the PACU: Incidence, factors and modulation

(PhD Tobias Schreyer)

 

2) Pain chronification

Over the last five years, it has become obvious that surgery is a major source of chronic pain, with some types of surgery (e.g. amputation, thoracotomy) being associated with chronic pain incidences of over 50% one year after surgery. In view of the poor prognosis and therapeutic response of such chronic pain, the prevention of chronic pain after surgery is a major societal challenge. A further reason for the attractiveness of researching the mechanisms of chronic pain after surgery is that we can follow its entire course from before the initiating trauma until the actual development of chronic pain. This knowledge may also help provide insight into the chronification of other types of pain.

In the context of this research programme, we have set up a number of studies documenting the course of postoperative alterations in pain and sensory processing for at least one year after surgery. We are studying these alterations by applying batteries of multimodal QST at different anatomical locations at multiple timepoints. These QST test batteries involve both passive and active approaches. Passive QST typically involves the determination of thresholds or psychophysical dose-response curves for pain using a variety of stimuli to different tissues. Using active QST, we determine how pain and sensory processing alter in the presence of various conditioning stimuli, e.g. repeated stimuli to test facilitation to temporal summation, or ice-water bucket testing to test descending inhibitory modulation. In collaboration with NICI and the F.C. Donders Centre we are extending this research by further studying both primary and secondary pain processing using fMRI and neurophysiological testing (single run EPs, ERPs, MEP). As for acute pain, this will permit much greater insight into higher, cognitive aspects of pain processing, as well as broadening our understanding of the detailed working of neural processing networks involved in nociception and subsequent pain chronification. Via collaboration with the Department of Human Genetics we are now starting to investigate the impact of variations in the human genome (e.g. opioid receptor differences due to melanocortin-1 receptor gene variants) on postoperative neuroplasticity and pain chronification.

To date, our research in this area has identified considerable variability in both the acute and the chronic post-surgical response to the nociception of surgery. There are first indications that differences in pain processing – passive as well as active – in the preoperative and acute postoperative period may permit prediction of patients at high risk of subsequent pain chronification. Furthermore, we have been able to gain more insight into the alterations of pain processing present in the postoperative period, and have thus been able to start testing a variety of pharmacological interventions, both prophylactic and therapeutic, aimed at positively influencing postoperative neuroplasticity and thus reducing pain chronification.

Main ongoing projects:

• Documenting the incidence of chronic pain after surgery: retrospective studies of various surgical interventions
• Neuroplasticity and pain chronification after surgical interventions: prospective studies of mastectomy, sternotomy and thoracotomy

(PhD Monique Steegers)

• Preventing Pain Chronification after Surgery: Using Quantitative Sensory Testing to Predict Patients at Risk and to Understand Mechanisms as a Basis for Effective Preventive Treatment Strategies (financed by ZONMW)
• Relative Contributions of Humoral and Nerve Nociceptive Inputs to Postoperative Central Sensitisation and Pain: Interaction of Extended Perioperative COX-2 Inhibition and Local Anaesthetic Blockade for Breast Malignancy Surgery (financed by an independent investigator research grant from Pfizer)

 

3) Chronic pain syndromes

Chronic pain is a major societal problem, both from the medical and from the employment point of view. In the Netherlands, for example, population prevalences of 40% are reported for chronic low back pain. Chronic pain, once established, is difficult to treat and has a poor prognosis, with 32% of chronic low back pain patients, for example, being unable to work at all. Thus the prevention of chronic pain should be a major goal, as already discussed above.  more...

Main ongoing projects:

• Neuroplasticity and the chronic pain of pancreatitis
• Effects of therapeutic interventions on neuroplasticity and pain in chronic pancreatitist

(PhD Hessel Buscher)

• Visceral and somatic QST colonic surgery: an observational study
• Complex visceral pain syndromes: effects on visceral and somatic QST

(PhD Willem Brinkert)

• Are segmental nerve blocks useful in the identification and treatment of spinal segmental pain in patients with chronic radiating low back pain without overt focal neurological deficits?

(PhD André Wolff)

• Pain mechanisms in patients with CRPS type I: An fMRI study
• Pain mechanisms in patients with chronic low back pain: An fMRI study

(PhD Noortje Vis)