Search

Background: In the chronic stage of stroke, previous work has shown that the worse the hand motor deficit, the greater the shift of primary motor cortex (M(1)) activation towards the contralesional hemisphere (ie, unphysiological) balance. Whether the same relationship applies at earlier stages of recovery in serially studied patients is not known.Methods: fMRI of fixed-rate auditory-cued affected index-thumb tapping was obtained at two time points (mean 36 and 147 days poststroke) in a cohort of nine patients with ischaemic stroke (age: 56+/-9 years; three women/six men; seven subcortical, one medullary and one cortical). On each fMRI day, the unaffected/affected ratio of maximal index tapping rate (IT-R) was obtained. To assess the M(1) hemispheric activation balance, the authors computed the classic Laterality Index (LI). The correlation between LI and IT-R was computed for each time point separately.Results: The expected correlation between LI-M(1) and IT-R, that is, motor performance worse with more unphysiological LI, prevailed at both time points (Kendall p=0.008 and 0.058, respectively), with no statistically significant difference between the two regressions. The same analysis for the dorsal premotor cortex and the supplementary motor area showed no significant correlation at either time-point.Conclusion: These results from a small cohort of longitudinally assessed patients suggest that the relationship between M(1) laterality index and hand motor performance appears independent of time since onset of stroke. This in turn may suggest that attempting to restore the hemispheric balance by enhancing ipsilesional M(1) and/or constraining contralesional M(1) activity may have consistent efficacy throughout recovery. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Quantifying intrinsic components of movement may help to better understand the nature of motor deficits after stroke. Here we quantify the ability of stroke patients to finger tap in rhythm with auditory cues given at physiological rate. Methods: Using tri-axial accelerometry, we measured tapping regularity (Regularity Index) during auditory-cued index-to-thumb tapping at 1.25Hz in 20 prospectively selected right-handed chronic stroke patients (mean age 61 yrs) and 20 right-handed healthy subjects (7 young and 13 age matched; mean age 24 and 58 yrs, respectively). With the aim to validate our method, two measures of clinical deficit, the European Stroke Scale (ESS) and the maximum number of index-thumb taps in 15s (IT-Max) were recorded on the same day. Results: There was no effect of age or hand used on the Regularity Index in the control subjects. In patients, the Regularity Index of their affected hand was significantly worse compared to their unaffected hand and to age-matched controls (p <0.05 and p <0.01, respectively). The Regularity Index significantly correlated with the ESS and IT-Max in the clinically expected direction (p =0.025 and 0.001, respectively). Conclusion: These data indicate that our method has validity to quantify finger-tapping regularity. After stroke, there is a deficit in the ability to keep pace with auditory cues that correlates, but does not equate, with other indices of motor function. Quantifying tapping regularity may provide novel insights into the mechanisms underlying recovery of finger dexterity after stroke. [Copyright &y& Elsevier]