Short-Term Recovery of Limb Muscle Strength After Acute Stroke

1. Short-Term Recovery of Limb Muscle Strength After Acute Stroke Arch Phys Med Rehabil 2003; 84: 125-30 Andrews AW, Bohannon RW Department of Physical Therapy Education, Elon University, Elon

2. Background • Strength after stroke • correlates with functional activities • e.g. transfer, gait, stair climbing • Predict the future outcome • e.g. status of motor function, functional status at discharge, length of stay, discharge destination, mortality

3. Background • Previous studies used MMT to measure strength • Strength scores use ordinal scale that is not norm referenced • Force transducer provide force measurement in real numbers

4. Background • Previous researchers have used instruments to measure post-stroke recovery of muscle strength, but only single joint or action • e.g. grip strength, knee flexion and extension • Changes of strength noted in none affected side were not compared with normative reference values

5. Background • Comorbid diseases occur more frequently among stroke survivors than matched controls • Relation of comorbidities with functional outcomes and mortality have been addressed • no studies about the influence of comorbidities on the recovery of strength

6. Purposes • Norm-referenced • Objective measurements • Muscle strength impairment at admission and discharge • Relation between comorbidities and the recovery of strength

7. Norm reference • Normative Values for Isometric Muscle Force Measurements Obtained With Hand-held Dynamometers • Physical Therapy 1996; 76:248-59 • A Williams Andrews, Micheal W Thomas, Richard W Bohannon

8. Tested by dynamometer • 156 subjects, ages of 50-79 years • Tested action: • Shoulder flexion, abduction, medial and lateral rotation • Elbow flexion and extension • Wrist extension • Hip flexion and abduction • Knee flexion and extension • Ankle dorsiflexion

9. Result: gender, age, and weight were identified as independent predictors of force for all muscle actions • Y= a - b*(S) + b*(W) – c* (A) • Multiple correlations associated with the regression equations: 0.624-0.869

10. Subjects • 50 inpatients in rehabilitation unit at the University of North Carolina Hospitals between 1994-1997 • Rehabilitation emphasizing early movement, exercise with resistance, balance training in sitting and standing, daily functional activities • 3 hours of PT, OT and recreational therapy on weekday and at least 1 hour on weekend day

11. Subjects • Diagnosis of acute stroke • Sudden loss of neurological function, caused by vascular injury to the brain • More than 90% of patients had neuroimaging evidence of acute stroke

12. Exclusion criteria • Unable to follow directions • e.g global aphasia • Strength testing was contraindicated • e.g. Recent cardiac surgery

13. Subject characteristics

14. comorbidies • Only comorbidies known to affect strength or mobility were recorded, e.g. arthritis, hip fracture, peripheral arterial disease, traumatic injury, chronic obstructive pulmonary disease, alcohol abuse, joint replacement, congestive heart failure, diabetes

15. Methods • Retrospective analysis • convenience sample • single-blinded • One examiner • Tested on admission and discharge • Same testing device (Hand-held dynamometer) and protocol

16. Tested actions • Shoulder abduction • Elbow flexion • Elbow extension • Wrist extension • Hip flexion • Knee extension • Ankle dorsiflexion

17. Test position • Gravity neutral position • Dynamometer was placed perpendicular to the body segment • As distal as possible • Peak forces abtained

18. Statistical analysis • Systat, version 10.0 • Mixed model (2×2×7×2×3) ANOVA • t-test

19. Results

20. Results

21. Results

22. Discussion • 7/7increase in strength on the weaker side • 4/7 increase in strength on the stronger side • Greater mean percentage increase on the weaker side • Greater potential for progress in weaker side • Thrust of rehabilitation intervention • Therapist emphasized strength gaze in weaker side • Natural neurological recovery

23. All 3 muscle of strong L/E showed a significant increase in muscle strength • Early standing and gait activities • Support most of their weight in standing through the stronger L/E

24. All muscle actions on BOTH sides were weaker than predicted • 10% or less of the corticospinal axons remain ipsilateral • Inactive for most of the day– disuse atrophy • Lack of exercise and nutritional support • Subjects with stroke may have led sedentary lifestyle

25. Presence of comorbidities and previous stroke did not adversely affect subject’s strength • acute cerebral lesion is the primary factor responsible for determining the degree of strength impairment • Short term recovery • May be found in larger sample of subjects

26. Limitation • Larger sample maybe needed • Longer period of F/U • DC on 29.4±15.4 days poststroke  may not be applicable in subjects who are more than 1 month poststroke

27. Limitation • Comorbidity index • Single unblinded examiner • Examiner also provide rehabilitation interventions to the subjects

28. conclusion • Muscle strength increased inBOTH sides • Early movement, exercise with resistance and function was insufficient to increase strength of BOTH sides to levels equal to pred. values  need for strengthening ex. • Comorbidities and previous stroke did not affected recovery of strength in early time post stroke. Extent of cerebral lesion maybe a much greater influence

29. Criticism • Strength： • Objective, measurement in real number • Multiple joint test (including U/Es and L/Es) • Weakness： • Statistics model is too complicated (2×2×7×2×3 ANOVA) • Insufficient data was shown • Insufficient explanation for the statistics result • Insufficient explanation for the modification of testing position • Unknown neurological status of the subjects

30. Thank you for your attention