Evaluating upper upper limb dysfunctions in patients with multiple sclerosis: an electromyography cross sectional study

Introduzione: Upper limb (UL) dysfunction and decreased UL use in daily life are common in persons with multiple sclerosis (MS). Therefore, there has been an increasing research interest in UL rehabilitation in MS. Evaluating UL dysfunction is more difficult compared with evaluating lower limb function because ULs are used to perform complex and multidimensional tasks (e.g., reaching, stabilizing, grasping and manipulating objects). By using outcome measures on the different ICF levels, one may be able to measure the complex and multidimensional character of the upper limb more completely and understand the impact of the underlying symptoms on ADL. However, the instrumental evaluation of the muscle pattern of activation could provide insights into the pathophysiological mechanisms involved in UL dysfunction in MS. Aim of this study is to validate an integrated clinical and instrumental protocol to evaluate UL impairments and muscle pattern deficits in patients with MS. Materiali e Metodi: A cross-sectional study was performed. Five patients with MS (age mean 55±8 years, range 45-65, EDSS 5.9±1.5, time from MS onset 13±7 years) and five age-matched healthy controls (age mean: 54±5 years, range 49-61) were enrolled. Upper limb function was evaluated by using clinical and instrumental assessments. The clinical assessment consisted of the Action Research Arm test (ARAT), the Fugl-Meyer Assessment Motor Scale (FM), Tremor Severity Scale, Nine Hole Peg Test, Motricity Index, Visual analog Scale for tiredness and fatigue. The instrumental assessment was performed by surface electromyographic (sEMG) analysis (BTS FREEEMG 300, BTS spa Milan Italy). To this end, the electromyographic activity of 7 UL muscles of the paretic side (deltoid anterior/posterior, biceps brachii, triceps brachii, grand pectoral, extensor/flexor digitorum) were detected by pairs of self-adhesive surface electrodes. During sEMG subjects were asked to perform two tasks belonging to the ARAT as follows. Task 1: “Hand to mouth” - Gross movement section. Task 2: “Grasp a 10cm-wooden-block” – Grasping section. An examiner manually defined three events in task 1 (start, mouth-touch, return) and four events in task 2 (start, grasping, release, return). Events allowed identifying 2 phases in the hand-to-mouth movement (P1, P2) and 3 phases in the reaching movement (P3, P4, P5). EMG signals processing was carried out using Matlab software (Mathworks Inc USA). The time requested to perform the task and the duration of sEMG activity during each phase was analyzed. Non-parametric statistical tests were used (SPSS, Ver. 23.0). Risultati: Clinical outcomes revealed the presence of moderate-to-severe UL deficits in patients with MS. Compared to healthy controls, patients with SM showed a significant increase in the time to perform each task (p<0.05) and significant differences in EMGs muscle activationduration. In particular , a significant reduction in the duration of muscle activity were was found in patients with SM in the Extensor Ddigitorum muscle during P1 (p=0.023), Ddeltoid Aanterior during P2 (p=0.02) and P3 (p=0.003), Pectoralis Major (p=0.018) and Extensor Ddigitorum in P4 (p=0.02) and Ddeltoid Aanterior and Eextensor Ddigitorum in in P4 (p=0.02) and P5 (p=0.026). A longer activation of the deltoid posterior was measured in patients with MS during P2 (p=0.033). Conclusione: Clinical and instrumental assessment procedures can allow defining better UL dysfunction in patients with MS. Preliminary data suggest that proximal muscle impairment may account for UL impairment. The analysis of By applying EMGs protocols torecorded in patients with MS and healthy adults, it will may substantially contribute to the understanding of the pathophysiological mechanisms underlying UL recovery, which in turn will lead to more effective strategies for UL rehabilitation. Future research should focus on investigating patterns of UL muscle activation in MS especially investigating the responsiveness of outcome measures after a rehabilitationn intervention..