Characterizing upper extremity motor behavior in the first week after stroke

Abstract

18 42 Conclusions: Early after stroke, spontaneous overall UE movement is reduced, and 43 movement shifts to unilateral use of the nonparetic UE. Thus, spontaneously-arising 44 UE motor behaviors early after stroke are potential substrates for two mechanisms 45 associated with poorer motor outcomes in animal models: learned non-use and 46 inhibition of motor recovery through training of the nonparetic side. Accurate UE motor 47 assessment requires two independent constructs: motor performance and quantity of 48 movement. These findings provide opportunities and measurement methods for studies 49 to develop new behaviorally-based stroke recovery treatments that begin early after 50 onset. 51 52 4 55 56 Of the estimated 7 million stroke survivors in the United States, up to 88% are 57 thought to have upper extremity (UE) motor involvement. This motor impairment is 58 usually disabling, leading to the need for modification or assistance in activities of daily 59 living (ADL) and reduced social participation (1-3) (4-6). 60 A series of animal studies have identified the first several days after stroke as a 61 time of great flux in sensorimotor function and physiology; these processes have long 62 term implications for recovery in animal models. A molecular program of injury and 63 reparative responses has been well documented (7-13) . Several motor behavioral 64 factors (timing of motor training, dosing, and use of non-paretic forelimb) and various 65 medications are active in meaningfully influencing forelimb motor recovery (14). These 66 factors also seem relevant to conventional rehabilitation in clinical settings, with the 67 potential to influence final motor outcomes in patients. One influential study examining 68 the amount and timing of structured motor activity suggests that initiation of motor 69 training beyond 5-14 days may be ineffective in restoring motor function, positing the 70 existence of a critical period in stroke recovery(15). In contrast, other work found that 71 overtraining early after stroke could actually lead to worse motor outcomes, and even 72 activity-dependent lesion enlargement (16, 17). These study results are of course not 73 mutually exclusive, and their relevance to humans with stroke remains unclear. Twenty 74 minutes daily of skill training in the less affected forelimb at has been shown to reduce 75 skill acquisition in the affected limb following a lesion of the motor cortex in rodents (18, 76 19). Were this true in human clinical populations, training compensation skills (in formal UE Motor Behaviors Early After Stroke 5 5 77 therapy or informally by a patient or family) in the nonparetic limb might inhibit motor 78 recovery. The effects of early "nonuse" behaviors have been well established in non-79 human primate models (20-23). 80 In clinical populations, the data are limited and inconclusive. In the case of early 81 initiation of rehabilitation, numerous retrospective studies have found that early 82 rehabilitation admission is associated with better outcomes (9, 24-26). ...