Clinical trial NCT01172795: Diffuse Noxious Inhibitory Controls (DNIC): Nociceptive Modulation and Interaction With Neurocognitive Performance in Chronic Pain
Study type: OBSERVATIONAL
Overall status: UNKNOWN
Conditions: Fibromyalgia
Whiplash
Chronic Pain
Keywords: Whiplash associated disorder
chronic pain
neural inhibition
neuropsychological tests
Lead sponsor: Vrije Universiteit Brussel
Sponsor class: OTHER
Collaborators: name: Research Foundation Flanders
First posted: 2010-07-30
Enrollment: 100
Sex: ALL
Minimum age (years): 18
Maximum age (years): 65
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Observational model: CASE_CROSSOVER
Time perspective: CROSS_SECTIONAL
Sampling method: NON_PROBABILITY_SAMPLE
Study population: Thirty patients with FM, 30 patients with WAD and 30 healthy pain-free control subjects will be enrolled. All three groups will be comparable for age, gender, education level and socioeconomic status; both patient groups will be comparable for illness duration. Sample size was calculated based on a power analysis (0.80), based on the assumption of a 20% difference of DNIC functioning after neurocognitive testing.

Brief summary: Diffuse noxious inhibitory control In order to quantify central sensitization in chronic pain patients, the Diffuse Noxious Inhibitory Control (DNIC) model has been used frequently. DNIC relies on painful conditioning stimulation of one part of the body to inhibit pain in another part, to remove the "noise" and to focus on relevant stimuli.

Earlier studies provided evidence for malfunctioning of DNIC in Fibromyalgia (FM) patients. However, the cause of this impairment is not yet elucidated, and further study is required to unravel the pathophysiology of DNIC in FM.

Hypothalamus-Pituitary-Adrenal (HPA) axis Besides neural mechanisms, also hormonal abnormalities could cause altered pain processing. Cortisol is released in answer to pain to suppress the pain. Given the evidence for hypofunction of the hypothalamic-pituitary-adrenal axis and the lower cortisol release in response to stressors in a proportion of FM patients and in chronic whiplash associated disorders (WAD) patients, the relation between pain and cortisol in these patients may be an interesting topic to consider.

Neurocognitive performance Besides chronic pain, people with chronic WAD and FM suffer from severe concentration difficulties and decreased neurocognitive capabilities (reduced reaction time, short term memory deficits etc. The decreased neurocognitive performance is known to be related to pain severity in various chronic pain populations. It is hypothesized that malfunctioning of descending inhibitory pathways and subsequent chronic pain experience precludes optimal neurocognitive performance.

Objectives The present investigation addresses the (patho)physiological mechanisms of DNIC in chronic pain populations.

1. Firstly, patients with FM, chronic WAD and healthy controls are compared regarding functioning of DNIC, cortisol levels and response and neurocognitive performance (case-control).
2. Secondly, the possible interaction between the functioning of DNIC, cortisol and neurocognitive performance is studied in patients with FM, WAD and healthy control subjects (cross-sectional).
3. Thirdly, to examine whether a fatiguing neurocognitive stressor changes DNIC and cortisol levels in patients with FM, chronic WAD or healthy sedentary control subjects.


Eligibility criteria: Inclusion Criteria:

* 30 FM group: comply with the diagnostic criteria for FM as defined by the American College of Rheumatology.
* 30 WAD group: comply with the criteria of the Quebec Task Force (grade I to III)
* 40 healthy pain-free control subjects
* Dutch speaking
* aged between 18 and 65 years.

Exclusion Criteria:

* FM patients reporting a history of a whiplash trauma
* WAD patients fulfilling the diagnostic criteria for FM
* healthy control subjects cannot suffer any pain complaints
* cannot be pregnant or until 1 year postnatal
* asked to stop analgesics 48 hours prior to study participation, not to undertake physical exertion, and to refrain from consuming caffeine, alcohol or nicotine on the day of the experiment.

Primary outcomes:
measure: pain inhibition efficacy
timeFrame: immediately (5 minutes) before and after intervention (relaxation or neurocognitive test battery)
Secondary outcomes:
measure: neurocognitive performance
timeFrame: once in the study design, immediately (5 minutes) preceded and followed by the pain measurements
measure: cortisol response to pain
timeFrame: immediately (1 minute) before and after pain measurements
Other outcomes:
Locations:
city: Brussels
country: Belgium
facility: Vrije Universiteit Brussel
Study officials:
References: