Prediction of upper limb recovery post-stroke using wrist motor impairments

More than 70% of people with stroke exhibit upper limb disability at one year. An understanding of upper limb motor recovery, and prediction of upper limb functional activity (ULFA) based on motor impairment, are important to inform rehabilitation.Recovery of upper limb motor impairment (measured by short form of the Fugl-Meyermotor scale), wrist motor impairments (measured by the redesigned wrist rig), andULFA (measured by the Streamlined Wolf Motor Function Test for use with sub-acutepatients) at 2, 4, 8,12 and 26 weeks were investigated. Relationships between ULFA at26 weeks and wrist motor impairments at each assessment point are reported, as wellas prediction values for ULFA at 26 weeks, based on wrist motor impairments at 2, 4, 8 and 12 weeks.Three motor impairment phenomena, sub-divided into eight categories, weremeasured from 11 impairment indices. These were: 1) negative (a reduction of motoractivity): range of active movement; muscle weakness; motor control accuracy; delayed muscle onset timing; 2) positive (excessive motor activity): spasticity and coactivation;and 3) secondary (later changes associated with negative and positive impairments):contracture and non-neural stiffness. Test-retest reliability of each impairment index was tested with 14 stroke participants at 8 weeks. Construct validity was tested in 25 stroke participants at two and 26 weeks post-stroke and with 25 matched pair healthycontrols. All impairment indices demonstrated good to excellent test-retest reliability (intra-class correlation coefficient 0.78-0.99). The minimal detectable change of each index was established as a benchmark value. Wrist active range of motion (AROM), flexor and extensor isometric force (IF), sine and step tracking index (TI), path length,muscle onset timing and stretch index were statistically significantly different (p<0.05) between stroke and healthy participants, representing good construct validity.Fifty-two stroke participants were recruited into a longitudinal study. Upper limb motor impairment, ULFA, range of active movement and muscle weakness improved rapidly between weeks two and four with considerably slower improvement between weeks 4 and 26. Recovery profiles could be divided into three categories: 1) high scores at 2 weeks with continuous improvement over 26 weeks; 2) low to moderate scores at 2 weeks with continuous improvement over 26 weeks; and 3) zero scores at 2 weeks with little or no improvement at 26 weeks. Generally, ULFA at 26 weeks was more related to the negative (r 0.39 to 0.78; p<0.05) than to the positive (r-0.40 to -0.54; p<0.05) or the secondary (r,0.37 to 0.66; p<0.05) motor impairments. Range of active movement, muscle weakness spasticity and contracture are good predictors of ULFA at 26 weeks (OR between 1.02, 95%CI 1.01-1.04 to OR 7.00, 95%CI 2.19-22.48). This is the first exploratory study to demonstrate a prediction of ULFA based on a variety of wrist motor impairments. The findings may assist therapists to customise rehabilitation programmes during the 26 weeks of stroke recovery.