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Barbero M1, Falla D2, Agnelotti M3, Trenta D3, Gallace A4,5, Cescon C1, Corbertta D6
1University of Applied Sciences and Arts of Southern Switzerland, Department of Business Economics, Health and Social Care, Manno, Switzerland, 2University of Birmingham, Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, Birmingham, United Kingdom, 3Vita-Salute San Raffaele University, Bachelor's Degree in Physiotherapy, Milan, Italy, 4University of Milano-Bicocca, Department of Psychology, Milan, Italy, 5Milan Center for Neuroscience, Milan, Italy, 6San Raffaele Scientific Institute, Laboratory of Analysis and Rehabilitation of Motor Function, Milan, Italy
Background: Digital pain drawings are used to assess pain location and pain extent in people with pain disorders including those with chronic low back pain (CLBP). Previous studies have confirmed that people can report their painful area in a reliable way. However, the conscious sense of body and proprioception can be impaired in patients with CLBP which may affect the validity of pain drawings. Investigations which asses the capacity and accuracy of patients with CLBP in locating painful sensations on digital body charts (DBC) are needed.
Purpose: The aim of this study was to evaluate how consistently people with and without CLBP can indicate the location of nociceptive stimuli applied over their back when reporting on a DBC.
Methods: Fourteen patients with CLBP and 36 healthy volunteers participated in the study. A grid of four rows and five columns was drawn over the participants' lumbar region. Six circular electrodes connected to a current stimulator were applied at points on the grid: one on the cross between column three and row four and five in the remaining crosses by means of a randomisation procedure. Additionally, six electrodes disconnected from the electrical stimulator were distributed over the remaining crosses. Volunteers were blinded to the electrode locations. Eight painful electrocutaneous stimuli were randomly delivered to each connected electrode. Participants were instructed to draw where they perceived each painful stimulation using a DBC presented on a tablet. The DBC was centred on a canvas 768x1024 pixels (pxl), and pain location was defined by X and Y coordinates. For each stimulated electrode the barycentre was computed for the eight locations reported on the DBC. The consistency of participants in reporting the location of painful stimulation was described using three variables: the standard deviation of the X coordinates (X-sd), the standard deviation of the Y coordinates (Y-sd) and the mean distance from the barycentre. The consistency in locating the nociceptive stimuli was compared between groups using Mann-Whitney U test.
Results: In the CLBP participants, the median(IQR) X-sd was 9.8(12.15) pxl, the median(IQR) Y-sd was 19.5(25.3) pxl and the median(IQR) D-bar was 19.7(13.2) pxl. In healthy volunteers, the median(IQR) X-sd was 10.3(9.1) pxl, the median(IQR) Y-sd was 18.2(12.9) pxl and the median(IQR) D-bar was 18.3(10.5) pxl. No significant group difference was found in reporting the painful stimuli.
Conclusion(s): The median variability in locating nociceptive stimulations applied over the lumbar region was ~3 mm for the horizontal direction and ~5 mm for the vertical, indicating that the consistency in reporting the location of nociceptive stimuli to the lumbar region is higher in the horizontal direction than in the vertical direction. Patients with CLBP showed no deficits in the capacity to consistently report the location of painful stimuli applied over their lower back.
Implications: Our findings suggest that persons with CLBP can identify the location pain on DBC. Moreover, nociceptive stimulation can be used to assess how well people with CLBP can locate and consistently report the location of painful stimuli. This may be a relevant clinical test which can be explored in other populations.
Keywords: Pain drawings, Low back pain, Pain assessment
Funding acknowledgements: No funding has been received for the conduct of this study.
Purpose: The aim of this study was to evaluate how consistently people with and without CLBP can indicate the location of nociceptive stimuli applied over their back when reporting on a DBC.
Methods: Fourteen patients with CLBP and 36 healthy volunteers participated in the study. A grid of four rows and five columns was drawn over the participants' lumbar region. Six circular electrodes connected to a current stimulator were applied at points on the grid: one on the cross between column three and row four and five in the remaining crosses by means of a randomisation procedure. Additionally, six electrodes disconnected from the electrical stimulator were distributed over the remaining crosses. Volunteers were blinded to the electrode locations. Eight painful electrocutaneous stimuli were randomly delivered to each connected electrode. Participants were instructed to draw where they perceived each painful stimulation using a DBC presented on a tablet. The DBC was centred on a canvas 768x1024 pixels (pxl), and pain location was defined by X and Y coordinates. For each stimulated electrode the barycentre was computed for the eight locations reported on the DBC. The consistency of participants in reporting the location of painful stimulation was described using three variables: the standard deviation of the X coordinates (X-sd), the standard deviation of the Y coordinates (Y-sd) and the mean distance from the barycentre. The consistency in locating the nociceptive stimuli was compared between groups using Mann-Whitney U test.
Results: In the CLBP participants, the median(IQR) X-sd was 9.8(12.15) pxl, the median(IQR) Y-sd was 19.5(25.3) pxl and the median(IQR) D-bar was 19.7(13.2) pxl. In healthy volunteers, the median(IQR) X-sd was 10.3(9.1) pxl, the median(IQR) Y-sd was 18.2(12.9) pxl and the median(IQR) D-bar was 18.3(10.5) pxl. No significant group difference was found in reporting the painful stimuli.
Conclusion(s): The median variability in locating nociceptive stimulations applied over the lumbar region was ~3 mm for the horizontal direction and ~5 mm for the vertical, indicating that the consistency in reporting the location of nociceptive stimuli to the lumbar region is higher in the horizontal direction than in the vertical direction. Patients with CLBP showed no deficits in the capacity to consistently report the location of painful stimuli applied over their lower back.
Implications: Our findings suggest that persons with CLBP can identify the location pain on DBC. Moreover, nociceptive stimulation can be used to assess how well people with CLBP can locate and consistently report the location of painful stimuli. This may be a relevant clinical test which can be explored in other populations.
Keywords: Pain drawings, Low back pain, Pain assessment
Funding acknowledgements: No funding has been received for the conduct of this study.
Topic: Musculoskeletal: spine; Pain & pain management; Outcome measurement
Ethics approval required: Yes
Institution: San Raffaele Scientific Institute, Milan, Italy
Ethics committee: Human Research Ethics Committee of San Raffaele Scientific Institute
Ethics number: 92/int/2017
All authors, affiliations and abstracts have been published as submitted.
