Functional Deficits in the Less-Impaired Arm of Stroke Survivors Depend on Hemisphere of Damage and Extent of Paretic Arm Impairment

Abstract

Background. Previous research has detailed the hemisphere dependence and specific kinematic deficits observed for the less-affected arm of patients with unilateral stroke. Objective. We now examine whether functional motor deficits in the less-affected arm, measured by standardized clinical measures of motor function, also depend on the hemisphere that was damaged and on the severity of contralesional impairment. Methods. We recruited 48 left-hemisphere-damaged (LHD) participants, 62 right-hemisphere-damaged participants, and 54 age-matched control participants. Measures of motor function included the following: (1) Jebsen-Taylor Hand Function Test (JHFT), (2) Grooved Pegboard Test (GPT), and (3) grip strength. We measured the extent of contralesional arm impairment with the upper-extremity component of the Fugl-Meyer (UEFM) assessment of motor impairment. Results. Ipsilesional limb functional performance deficits (JHFT) varied with both the damaged hemisphere and severity of contralesional arm impairment, with the most severe deficits expressed in LHD participants with severe contralesional impairment (UEFM). GPT and grip strength varied with severity of contralesional impairment but not with hemisphere. Conclusions. Stroke survivors with the most severe paretic arm impairment, who must rely on their ipsilesional arm for performing daily activities, have the greatest motor deficit in the less-affected arm. We recommend remediation of this arm to improve functional independence in this group of stroke patients.

Keywords: functional deficits; hemisphere-specific deficits; ipsilesional deficits; motor lateralization; stroke.

Figure 1.

Mean and standard errors of the total time (seconds) to complete the JHFT for control groups and stroke groups are shown, separated by contralesional arm impairment severity. Stroke participants using their left hand (shown in black) had left hemisphere damage. Stroke participants using their right hand (shown in gray) had right hemisphere damage. Groups not connected by same letter are significantly different.

Figure 2.

Mean and standard errors of the total time (seconds) to complete the JHFT for control groups and stroke groups are shown, with the exclusion of apraxic participants. Stroke participants using their left hand (shown in black) had left hemisphere damage. Stroke participants using their right hand (shown in gray) had right hemisphere damage. Groups not connected by same letter are significantly different.

Figure 3.

The X-axis represents participants’ contralesional arm impairment severity measured by the Fugl-Meyer Assessment in stroke participants. The Y-axis shows the T-score representing grip strength (kg) measured using a hand dynamometer. Mean and standard errors are shown. Groups not connected by same letter are significantly different.

Figure 4.

The X-axis represents participants’ contralesional arm impairment severity measured by the Fugl-Meyer Assessment in stroke participants. The Y-axis shows the participants’ T-score representing the total time to place all pegs. A higher T-score indicates faster performance. Mean and standard errors are shown. Groups not connected by same letter are significantly different.