Abstract
Background.
Addressing the role of somatosensory impairment, that is, afferent
pathway integrity, in poststroke motor recovery may require
neurophysiological assessment.
Objective.
We investigated the
longitudinal construct validity of position-cortical coherence (PCC),
that is, the agreement between mechanically evoked wrist perturbations
and electroencephalography (EEG), as a measure of afferent pathway
integrity.
Methods. PCC was measured serially in 48 patients
after a first-ever ischemic stroke in addition to Fugl-Meyer motor
assessment of the upper extremity (FM-UE) and Nottingham Sensory
Assessment hand-finger subscores (EmNSA-HF, within 3 and at 5, 12, and
26 weeks post stroke. Changes in PCC over time, represented by percentage
presence of PCC (%PCC), mean amplitude of PCC over the affected (Amp-A)
and nonaffected hemisphere (Amp-N) and a lateralization index
(L-index), were analyzed, as well as their association with FM-UE and
EmNSA-HF. Patients were retrospectively categorized based on FM-UE score
at baseline and 26 weeks post stroke into high- and low-baseline
recoverers and nonrecoverers.
Results.
%PCC increased from baseline to 12 weeks post stroke (β = 1.6%, CI = 0.32% to 2.86%, P
= .01), which was no longer significant after adjusting for EmNSA-HF
and FM-UE. A significant positive association was found between %PCC,
Amp-A, and EmNSA-HF. Low-baseline recoverers (n = 8) showed
longitudinally significantly higher %PCC than high-baseline recoverers
(n = 23). Conclusions.
We demonstrated the longitudinal construct
validity of %PCC and Amp-A as a measure of afferent pathway integrity. A
high %PCC in low-baseline recoverers suggests that this measure also
contains information on cortical excitability. Use of PCC as an
EEG-based measure to address the role of somatosensory integrity to
motor recovery post stroke requires further attention.
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