Characterization of the influence of the dominant tract on hand closing
post stroke based on the Fugl-Meyer score
Abstract
While stroke survivors with moderate or mild impairment are typically
able to open their hand at will, those with severe impairment are not.
Abnormal synergies govern the arm and hand in stoke survivors with
severe impairment, so hand opening, which is required to overcome the
working synergy, is a task extremely difficult for them to achieve. It
is universally accepted that alternative tracts including the
cortico-reticulospinal tract (CRST), employed in the case that the
corticospinal tract (CST) is damaged by stroke, brings about such
abnormal synergies. Here we note that hand closing is enabled by
alternative tracts as well as the CST, and raise a research question:
does motor characteristics while closing the hand depend on the
integrity of the CST? In this study, we evaluate the ability of 17
stroke survivors to flex and relax the metacarpophalangeal (MCP) joints
and investigate whether motor characteristics can be distinguished based
on CST integrity which is estimated using upper-extremity Fugl-Meyer
(UEFM). UEFM scores have been perceived as an indirect indicator of CST
integrity. We found that participants with the UEFM score above a
certain value, who are assumed to use the CST, moves the MCP joints more
smoothly (p<0.05) and activates the flexor to flex the joints
faster (p<0.05), in comparison to participants with low UEFM
scores, who are assumed to use alternative tracts. The results present
evidence that use of alternative tracts (i.e. the CRST) results in a
degradation in movement smoothness and slow activation of the MCP
flexor.