Changes in Pain Sensitivity and Conditioned Pain Modulation During Recovery From Whiplash-associated Disorders

Abstract

Objectives: To investigate the pain-sensory profile of patients with whiplash-associated disorders (WAD) prior and post 2-weeks of standardized rehabilitation and after at 6months follow-up.Methods: Twenty-two WAD-participants (Grade-II; 14 women) and 22 sex-and agematched healthy controls were enrolled. Pressure pain thresholds (PPTs) were assessed at local and distal muscles. Conditioned pain modulation (CPM) of PPTs was assessed using cuff-pressure around the upper-arm. Referred area of pain following suprathreshold pressure stimulation of the infraspinatus muscle was recorded on a body chart.Psychometric variables (Pain intensity, area of perceived pain, pain catastrophizing, kinesiophobia, sleep problems, depression level) were assessed. WAD-group additionally completed the Neck Disability Index (NDI). Results:The WAD-group demonstrated lower local PPTs compared to controls at all timepoints (P<0.05) and lower distal PPTs at baseline and at 2 weeks when compared to 6-months (within-group) (P<0.05). The WAD-group had a reduced CPM response and larger induced referred pain areas compared to controls (P<0.05), while no within-group changes were observed at any time point. The WAD-group reported higher pain intensity and perceived area of pain compared to controls at all timepoints (P<0.05) and a mean NDI-score of 41% at baseline, 16% at 2-weeks, and 4% at 6-months.Furthermore, the WAD-group reported improvements in all other psychometric variables (P<0.05), although only pain catastrophizing levels were comparable to controls at 2-weeks. Discussion: PPTs but not CPM improved in the WAD-group and were comparable to controls following 2-weeks following standardized rehabilitation, indicating that normalization of CPM may not be required to recover from WAD.

Pressure pain thresholds in a real-world chiropractic setting: topography, changes after treatment, and clinical relevance?

“…In order to move this area forward, more studies are needed which take into account potential sources of error, such as those discussed in the preceding discussion. Also, we have a limited understanding of PPT as a clinically relevant outcome measure—it is not evident that an increase in PPT should be correlated with a clinical improvement [ 9 , 48 ]. Researchers and clinicians should be cautious about assuming such a relationship exists.…”

Long-term consistency of clinical sensory testing measures for pain assessment

“…This reliability study is a secondary analysis of data from a previously published prospective case-control study [20]. This manuscript followed the Guidelines for Reporting Reliability and Agreement Studies (GRRAS) [21].…”

“…Outcomes Study Sleep Scale [23], depressive symptoms with the Beck Depression Inventory [24], and pain-related catastrophizing thoughts with the Pain Catastrophizing Scale [25]. The purpose of completing these questionnaires was to ensure that these three domains remained similar across the six months [20]. Additionally, before the second and third testing, participants were asked to confirm that they still fulfilled the inclusion criteria for the study.…”

“…At the beginning of each session, the rater followed a similar familiarization protocol to ensure that instructions to the participants were similar between days. First, the rater explained to the participants that "Pressure pain threshold is the pressure reached when you first feel that the pressure becomes painful" [20]. Here, particular emphasis was placed on evaluating the PPT and not the tolerance.…”

“…The location of the PPT sites was identified by palpation of anatomical landmarks in addition to using a tape measure. PPT sites were marked with semipermanent ink [20].…”