Unraveling Back Pain Chronicity: an EMG and EEG Study

A self-reported rating by participants for experienced low back pain, which was assessed at baseline, midway the RAM block (during the 90s intermission) and after the RAM. Participants had to indicate on a horizontal axis of 10 cm how much LBP they experienced at that moment with at the left side of the axis (0) 'no pain all' and on the right side of the axis (10) 'maximal/worst pain ever experienced'. The numeric score (0-10) was calculated by the researcher and was not visible for participants.

A self-reported rating by participants for assessing how fatiguing the RAM was. This was assessed after the RAM task. This is a vertical scale ranging from 6 at the top (no exertion) to 20 at the bottom ('maximal exertion') of the scale. Participants saw both incremental numbers from 6-20 and descriptions at numbers 7 ('very very light'), 9 ('very light'), 11 ('reasonably light'), 13 ('quite heavy'), 15 ('heavy'), 17 ('very heavy'), 19 ('very very heavy'), 20 ('maximal exertion').

The IPAQ was administered before each test session to question participants about the physical activities they performed during the last 7 days. This in order to control for week-to-week differences in physical exertion levels and in order to compare physical activity between subjects. Based on these scores 3 levels of physical activity could be determined with level 1 (low), 2 (moderate) and 3 (high) physical activity. These levels are calculated based on the amount of hours low, moderate and high exerting activities had been performed the last 7 days.

Demographical and physical characteristics were questioned in a self-developed general questionnaire as well as educational/occupational levels, substance and medication use, general physical and mental health at the beginning of test day 1.

Only a short part of the General Questionnaire was repeated at the start of test day two. Demographic, physical and educational/occupational information would not alter between 2 test days, so these sections were unnecessary to question again at test day 2. Therefore a shorter version with only questions about substance and medication use since the previous test day, general physical and mental health was administered on test day 2.

The HADS was administered before each test day in order to be able to assess feelings of anxiety and depression experienced during the last week. This without including physical aspects, but solely the mental aspects thereof. 14 items (7 for anxiety, 7 for depression) had to be answered on a 4-point Likert scale (0-3). A total score would then be calculated ranging from 0-7 (no depression/anxiety), over 8-10 (possible depression/anxiety), to 11-21 (likely depression/anxiety).

The PCS is a self-assessment scale that gives a valid indication of the amount of catastrophizing in both clinical and non-clinical populations. Catastrophizing plays an important role in the experience and consequent handling of pain. 13 statements have to be scored on a 5-point scale ranging from 0 ('not at all applicable') to 4 ('always applicable'). Total scores (0-52) as well as subscales for rumination (4 items), magnification (3 items) and helplessness (6 items) can be calculated.

The TSK is a questionnaire that assesses pain-related fear during everyday movements, and is mostly used for CLBP and fibromyalgia patient groups. It consists out of 17 items that can be subdivided into pathological somatic focus (5 items) and activity avoidance (8 items) questions. All statements have to be scored on a 4-point score, ranging from 1 ('strongly disagree') to 4 ('strongly agree'). A total score is calculated after inversion of the individual scores of items 4, 8, 12 and 16. A total score, and subscores for pathological somatic focus (5-20), and activity avoidance (8-32) can be calculated.

The PVAQ is a broad measure of attention to pain, which can be applied to various pain populations. It consists of 16 statements, and respondents have to indicate on a 6-point scale (0 = never, 6 = always) the extent to which these statements correspond to their behaviour in the last week.

The RMDQ specifically measures the physical condition of people with low back pain complaints and the manner in which this interferes with daily activities. It consists out of 24 questions about activities that might be disturbed by LBP. Respondents have to answer 'yes' or 'no' on each question to, leading to a total score (0-24) that reflects the amount of disability experienced.

The CSI is a questionnaire that assesses to which extent several central sensitization related aspects are present in the respondents. Therefore, respondents are required to score 25 statements on a 5-point Likert scale ranging from 0 ('never') to 4 ('always'). Furthermore, previous diagnostics of 10 sensitization-related syndromes (like fibromyalgia) are also assessed. Total scores on the CSI are divided subclinical (0-29), mild (30-39), moderate (40-49), severe (50-59), and extreme (60-100) regarding presence of central sensitization aspects.