Breckenridge J1,2, McAuley J3,4, Ginn K1
1University of Sydney, Medical Sciences, Sydney, Australia, 2Clinical Research Institute, Westmead, Australia, 3Neuroscience Research Australia (NeuRA), Sydney, Australia, 4University of New South Wales, Sydney, Australia
Background: Abnormalities in brain activation and structure have been associated with a number of chronic pain conditions.Primary sensory cortex representations of affected body parts and motor cortex abnormalities have been reported. One way of indirectly exploring these cortical changes in proprioceptive, somatosensory and related regions is with implicit motor imagery, an established method is via the left/right judgement task (LRJT). Altered motor imagery performance has been reported in chronic pain conditions, but it is not known to be altered in chronic shoulder pain. Frozen shoulder is a severe chronic musculoskeletal pain condition. Confusion surrounds its diagnosis and management. New methods of treatment are needed.
Purpose: The aim of this study was to determine if motor imagery performance is altered in people with frozen shoulder - and by implication if cortical changes are a feature of chronic shoulder pain.
Methods: Adults presenting with a unilateral, painful, stiff shoulder of unknown cause for at least 6 weeks duration with one third restriction of both active and passive range of motion were recruited. The SPADI score and NRS pain scores along with active and passive ROM were assessed. An age matched healthy control group adults with no shoulder pain were generated from a previous study. Motor imagery was assessed with an online bespoke version of the shoulder LRJT. RT and Accuracy were main outcome measures. Paired samples t-test was run to compare mean RTs for the frozen shoulder and the healthy shoulder. Independent samples t-test was run to compare frozen shoulder mean RTs with the healthy control group.
Results: Eighteen frozen shoulder participants (13 female) were recruited; mean age 52.9 years (±SD 8.1), worst pain NRS: mean 8.0/10 (±2.5); average pain NRS: mean 5.0/10 (± 2.3); mean SPADI score % 59.2 (±20.4). The healthy control group consisted of 141 participants (81 female), with mean age 52.7 (3.3) years.
Mean passive flexion (93.9°) and external rotation (19.4°) of the affected shoulder were significantly reduced compared to the unaffected shoulder (flexion 172.5°; external rotation 70.1°). Mean RT for images corresponding to the affected shoulder was 2331(1576) ms, which was significantly slower than mean RT for images corresponding to the unaffected/contralateral shoulder 2119 (1262) ms, (t17= 2.320, p = 0.033). The mean RT for images corresponding to the affected shoulder were also significantly slower than the mean RT of the healthy control participants 1783 (635) ms, (t157= -2.763, p = 0.006).
Conclusion(s): Motor imagery performance was altered in people with frozen shoulder as measured via the shoulder specific LRJT. People with frozen shoulder were slower at recognising images that corresponded to their frozen shoulder compared to images that corresponded to their healthy unaffected shoulder. They were also considerably slower and less accurate recognising images that corresponded to their affected shoulder than healthy age matched control subjects. This study provides evidence of maladaptive neuroplastic changes, both processing and reorganisation associated with frozen shoulder.
Implications: Maladaptive neuroplastic change is a feature of frozen shoulder, providing evidence for treatments aimed at reversing these changes, ultimately, training the brain to reduce chronic shoulder pain.
Keywords: Frozen shoulder, More imagery, LRJT
Funding acknowledgements: None
Purpose: The aim of this study was to determine if motor imagery performance is altered in people with frozen shoulder - and by implication if cortical changes are a feature of chronic shoulder pain.
Methods: Adults presenting with a unilateral, painful, stiff shoulder of unknown cause for at least 6 weeks duration with one third restriction of both active and passive range of motion were recruited. The SPADI score and NRS pain scores along with active and passive ROM were assessed. An age matched healthy control group adults with no shoulder pain were generated from a previous study. Motor imagery was assessed with an online bespoke version of the shoulder LRJT. RT and Accuracy were main outcome measures. Paired samples t-test was run to compare mean RTs for the frozen shoulder and the healthy shoulder. Independent samples t-test was run to compare frozen shoulder mean RTs with the healthy control group.
Results: Eighteen frozen shoulder participants (13 female) were recruited; mean age 52.9 years (±SD 8.1), worst pain NRS: mean 8.0/10 (±2.5); average pain NRS: mean 5.0/10 (± 2.3); mean SPADI score % 59.2 (±20.4). The healthy control group consisted of 141 participants (81 female), with mean age 52.7 (3.3) years.
Mean passive flexion (93.9°) and external rotation (19.4°) of the affected shoulder were significantly reduced compared to the unaffected shoulder (flexion 172.5°; external rotation 70.1°). Mean RT for images corresponding to the affected shoulder was 2331(1576) ms, which was significantly slower than mean RT for images corresponding to the unaffected/contralateral shoulder 2119 (1262) ms, (t17= 2.320, p = 0.033). The mean RT for images corresponding to the affected shoulder were also significantly slower than the mean RT of the healthy control participants 1783 (635) ms, (t157= -2.763, p = 0.006).
Conclusion(s): Motor imagery performance was altered in people with frozen shoulder as measured via the shoulder specific LRJT. People with frozen shoulder were slower at recognising images that corresponded to their frozen shoulder compared to images that corresponded to their healthy unaffected shoulder. They were also considerably slower and less accurate recognising images that corresponded to their affected shoulder than healthy age matched control subjects. This study provides evidence of maladaptive neuroplastic changes, both processing and reorganisation associated with frozen shoulder.
Implications: Maladaptive neuroplastic change is a feature of frozen shoulder, providing evidence for treatments aimed at reversing these changes, ultimately, training the brain to reduce chronic shoulder pain.
Keywords: Frozen shoulder, More imagery, LRJT
Funding acknowledgements: None
Topic: Musculoskeletal: upper limb; Pain & pain management
Ethics approval required: Yes
Institution: University of Sydney
Ethics committee: Human Ethics Committee
Ethics number: Protocol No. 05-2011/13645, Project reference number 2012/539
All authors, affiliations and abstracts have been published as submitted.
