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).

To this end we have developed a computerized database system systematically documenting postoperative pain, other undesirable symptoms and all therapeutic interventions in the postoperative period with a high temporal resolution. These data are linked with data on changes in pain and sensory processing as determined by batteries of quantitative sensory testing (QST) measured at multiple time points and anatomical locations. Our postoperative database is also linked to our intraoperative anaesthesia documentation system (NOVAS database which warehouses intraoperative data, e.g. drug interventions) to permit identification of risk factors for postoperative alterations in pain and its processing. Our research on pain and sensory processing is due to be extended using electrophysiological techniques (event-related potentials [ERPs], single-run evoked potentials [EPs]; collaboration with Nijmegen Institute for Cognition and Information [NICI]), permitting further insight in nociception processing and subsequent alterations in cognitive function.

At present our research focuses on origins, mechanisms and management of postoperative hyperalgesia, a phenomenon not only associated with increased postoperative pain, but also with resistance to analgesic interventions, other excitatory complications such as vomiting, and – ultimately – pain chronification. This research has already permitted us to identify risk factors – both preoperative and intraoperative – for patients more likely to suffer increased pain or to encounter problems with analgesic management during their post-anaesthesia recovery unit stay. The ongoing studies have further improved our understanding of factors likely to influence the success or failure of analgesic titration in the immediate postoperative period.

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. more...

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)