title: Complex Shoulder Instability: A combined study of functional MRI, Electromyography and 3-D motion analysis
Creators: name: Howard, AJ
Publisher: name: University of Liverpool Repository
Year: 2016

description: Purpose of Study : The pathophysiology of type II/III shoulder instability under the Stanmore Classification is not understood. This absence of knowledge prevents treatment strategies being devised or a proper understanding of existing therapies. This is the first study to approach this group of patients from both a cerebral and muscle analysis perspective. Methods : The assessment of shoulder movement was undertaken using two simple movements, forward flexion and abduction. The muscles around the shoulder (AD, MD, PD, UT, SA, BB, TM, LD, PM, SSP, ISP and SUB) were assessed in 21 individuals in the standing and supine position using EMG. In the supine position the movement was restricted to the movement possible in a Siemens 1.5 Tesla MRI Scanner. Patients were recruited with Polar type II/III shoulder instability, with their inclusion confirmed by the senior surgeon and physiotherapist. In total, 16 Polar type II/III patients were recruited along with 16 age-matched controls. The patients and the controls underwent an fMRI and EMG. The fMRI protocol involved movements of forward flexion and abduction in a 1.5 tesla MRI Scanner. The EMG movements tested were forward flexion and abductions to 90 degrees (AD, MD, PD, UT, SA, TM, LD, PM, BB, ISP). Both the patients and the controls completed questionnaires: the Western Ontario Shoulder Instability Index (WOSI), Oxford Shoulder Instability Score (OSIS) and Beck’s Depression Inventory. Results : Analysis of the EMG data in the normal shoulder group confirmed activations in both supine and standing positions; however the activations in the supine position were of a different character. There was increased activation in the patient group compared to the control group. In the patient group, with a voxel level familywise error rate (FWER) p=0.04, there was a unique activation at MNI coordinates -38 -26 56. The cluster FWER p&lt;0.001 showed additional clusters in the patient group in the Primary somatosensory cortex, BA 3, Primary Motor Cortex, BA 4, Premotor cortex, BA 6 and Dorsolateral prefrontal cortex, BA 9. When the WOSI and OSIS were used as a contrast, activations were seen in primary somatosensory cortex, BA 3, supplementary motor cortex, BA 11, orbitofrontal area, BA 26, cingulate gyrus and the amygdala. The WOSI and OSIS showed a dramatically different score in the patient group compared to the controls, save for one patient whose symptoms had largely resolved following muscle patterning physiotherapy. Conclusion : The EMG studies in the standing and the supine position confirmed the validity of the fMRI paradigm. The instability questionnaires, WOSI and OSIS confirmed the patient group selection. The unique activation (MNI -38 -26 56) occurred within the primary motor cortex, with the cluster level voxels stretching between both the somatosensory cortex and the motor cortex. The WOSI and OSI comparisons show similar activations. This is thought to be evidence of compensatory activation. This additional activation was also seen in the EMG analysis, with evidence throughout all of the muscles that greater activation was needed to complete simple movement. Overall, the comparative addition cortical and muscles activations in patient group simultaneously demonstrate dysfunction and compensatory strategies employed to achieve simple shoulder movement.