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Breaking Proportional Recovery After Stroke.
Neurorehabil Neural Repair 2019; :1545968319868718NN

Abstract

People with hemiparesis after stroke appear to recover 70% to 80% of the difference between their baseline and the maximum upper extremity Fugl-Meyer (UEFM) score, a phenomenon called proportional recovery (PR). Two recent commentaries explained that PR should be expected because of mathematical coupling between the baseline and change score. Here we ask, If mathematical coupling encourages PR, why do a fraction of stroke patients (the "nonfitters") not exhibit PR? At the neuroanatomical level of analysis, this question was answered by Byblow et al-nonfitters lack corticospinal tract (CST) integrity at baseline-but here we address the mathematical and behavioral causes. We first derive a new interpretation of the slope of PR: It is the average probability of scoring across remaining scale items at follow-up. PR therefore breaks when enough test items are discretely more difficult for a patient at follow-up, flattening the slope of recovery. For the UEFM, we show that nonfitters are most unlikely to recover the ability to score on the test items related to wrist/hand dexterity, shoulder flexion without bending the elbow, and finger-to-nose movement, supporting the finding that nonfitters lack CST integrity. However, we also show that a subset of nonfitters respond better to robotic movement training in the chronic phase of stroke. These persons are just able to move the arm out of the flexion synergy and pick up small blocks, both markers of CST integrity. Nonfitters therefore raise interesting questions about CST function and the basis for response to intensive movement training.

Authors+Show Affiliations

1 University of California at Irvine, Irvine, CA, USA.1 University of California at Irvine, Irvine, CA, USA.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31416391

Citation

Senesh, Merav R., and David J. Reinkensmeyer. "Breaking Proportional Recovery After Stroke." Neurorehabilitation and Neural Repair, 2019, p. 1545968319868718.
Senesh MR, Reinkensmeyer DJ. Breaking Proportional Recovery After Stroke. Neurorehabil Neural Repair. 2019.
Senesh, M. R., & Reinkensmeyer, D. J. (2019). Breaking Proportional Recovery After Stroke. Neurorehabilitation and Neural Repair, p. 1545968319868718. doi:10.1177/1545968319868718.
Senesh MR, Reinkensmeyer DJ. Breaking Proportional Recovery After Stroke. Neurorehabil Neural Repair. 2019 Aug 16;1545968319868718. PubMed PMID: 31416391.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Breaking Proportional Recovery After Stroke. AU - Senesh,Merav R, AU - Reinkensmeyer,David J, Y1 - 2019/08/16/ PY - 2019/8/17/entrez KW - movement KW - projections and predictions KW - proportional recovery KW - rating scales KW - rehabilitation KW - stroke SP - 1545968319868718 EP - 1545968319868718 JF - Neurorehabilitation and neural repair JO - Neurorehabil Neural Repair N2 - People with hemiparesis after stroke appear to recover 70% to 80% of the difference between their baseline and the maximum upper extremity Fugl-Meyer (UEFM) score, a phenomenon called proportional recovery (PR). Two recent commentaries explained that PR should be expected because of mathematical coupling between the baseline and change score. Here we ask, If mathematical coupling encourages PR, why do a fraction of stroke patients (the "nonfitters") not exhibit PR? At the neuroanatomical level of analysis, this question was answered by Byblow et al-nonfitters lack corticospinal tract (CST) integrity at baseline-but here we address the mathematical and behavioral causes. We first derive a new interpretation of the slope of PR: It is the average probability of scoring across remaining scale items at follow-up. PR therefore breaks when enough test items are discretely more difficult for a patient at follow-up, flattening the slope of recovery. For the UEFM, we show that nonfitters are most unlikely to recover the ability to score on the test items related to wrist/hand dexterity, shoulder flexion without bending the elbow, and finger-to-nose movement, supporting the finding that nonfitters lack CST integrity. However, we also show that a subset of nonfitters respond better to robotic movement training in the chronic phase of stroke. These persons are just able to move the arm out of the flexion synergy and pick up small blocks, both markers of CST integrity. Nonfitters therefore raise interesting questions about CST function and the basis for response to intensive movement training. SN - 1552-6844 UR - https://www.unboundmedicine.com/medline/citation/31416391/Breaking_Proportional_Recovery_After_Stroke L2 - http://journals.sagepub.com/doi/full/10.1177/1545968319868718?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -