People who experience whiplash, an injury caused by a sudden jerking movement of the head – usually the result of a motor vehicle accident – can go on to experience persistent pain and disability. This can happen in up to 40 percent of people with whiplash. The disorders caused by whiplash are grouped into Whiplash-associated disorders, or WAD. These include hypersensitivity (too strong) reaction to stimulation, either mechanical (touch), thermal (heat or cold), and/or electrical.
It has long been thought that psychological distress affects the amount of pain and the persistence of pain among patients with whiplash.
The authors of this study wanted to investigate the how psychological factors can affect the responses to stimuli. To evaluate the responses, researchers recruited 33 patients, 23 of whom were women, who had had neck pain for a minimum of 3 months, as the result of a motor vehicle accident. The patients’ average age was 37.7 months. This group was compared with a control group (no neck pain) of 32 subjects.
To assess the subjects, the researchers used the Neck Disability Index (NDI) so the patients could measure self-perceived pain and disability associated with their neck pain, the Visual Analog Scale (VAS) so the patients could rate their pain scales on a level of 0 to 10, with 10 being the worst imaginable, the General Health Questionnaire-28 (GHQ-28) to measure emotional distress, and the Pain Catastrophizing Scale (PCS).The researchers also measured the pressure pain thresholds and heat pain thresholds.
Five subjects – 3 from the whiplash group and 2 from the control group – complained of severe pain at a rate of 8 out of 10 without stimulation, so they were not included in the results, leaving a total of 30 patients in the whiplash group and 30 in the control group.
In comparing the subjects’ results, the researchers noted that there was no difference between the two groups when looking at the right and left sides, so the results were pooled together,left and right.
The researchers found that the subjects in the whiplash group had lower pain thresholds in tolerance to cold than did those in the control group. However, the whiplash group also had a higher level of psychological distress when measured through the questionnaires. In other areas, there were no differences between either group with the heat pain threshold, for example.
The authors conclude that although catastrophization among the whiplash group did result in a hypersensitivity to cold stimuli, it did not seem to have an effect on the other forms of stimuli. Therefore, the authors write, although psychological distress may play a role in some physical distress, it is not necessarily one of the main causes of pain.