Your doctor should be able to use vast amounts of this information to update your stroke protocols. If s/he doesn't do that you really need to have a talk with the president of the hospital about the competency of the stroke department head and your doctor. It is up to us stroke survivors to clear out all the dead wood in the stroke world, they will not police and correct themselves. Proven by decades of little to no progress in stroke.
Editorial: Principles Underlying Post-Stroke Recovery of Upper Extremity Sensorimotor Function – A Neuroimaging Perspective
Bruno J. Weder
Roland Wiest- 1Support Center for Advanced Neuroimaging (SCAN), Institute for Diagnostic and Interventional Neuroradiology, University Hospital Inselspital, University of Bern, Bern, Switzerland
- 2Department of Neurology, Kantonsspital St. Gallen, St. Gallen, Switzerland
- 3Department of Neurology, Centre of Neurology and Neuropsychiatry, LVR-Klinikum Düsseldorf, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
- 4Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
The Editorial on the Research Topic
A substantial proportion of stroke survivors suffer from long-term sensorimotor deficits of the contralesional arm and hand (1).
Neuroimaging, using a diversity of methods, has the potential to
uncover underlying principles of functional disabilities and recovery
characterizing patient groups as well as individual variability (2–6).
The present issue aims at (i) revealing the physiological mechanisms
and the long-term course of stroke recovery with respect to site and
size of lesions, (ii) correlating behavioral deficits and
electrophysiological parameters with imaging patterns, (iii) delineating
neural networks involved, and (iv) identifying sites where
interventions enhance the recovery process.
Seitz and Donnan
give an overview of mechanisms and disease-related limitations in
post-stroke recovery. They address two informative subsections
delineating time courses of the recovery process and state-of-the-art of
neurorehabilitative training to improve the stroke-induced neurological
deficit.
Auriat et al.
complete this clinical perspective with an overview on the use of
transcranial magnetic stimulation and multimodal neuroimaging to
estimate functional resources post-stroke. They provide a review of data
from studies utilizing DTI, MRS, fMRI, EEG, and brain stimulation
techniques, focusing on TMS and its combination with uni- and multimodal
neuroimaging methods with respect to their benefits and limitations.
Falcon et al.
used “The Virtual Brain (TVB),” an open source platform based on local
biophysical models. Using this platform, they simulated individuals’
brain activity linking structural data directly to a TVB model.
Correlating TVB parameters with graph analysis metrics, they obtained
evidence for a shift of global to local dynamics in chronic stroke
patients.
Buetefisch
reviews the role of an intact contralesional motor cortex (M1) in
post-stroke recovery of upper extremity motor function. The impact of
the contralesional M1, on the lesioned motor cortex, seems to be
promoting activity in the acute and inhibiting it in the chronic stage.
Supportive evidence comes from animal studies, including changes in
neurotransmitter systems, dendritic growth, and synapse formation. Thus,
the contralesional M1 may represent a treatment target during
rehabilitation.
Sharma and Baron
report an fMRI study of a finger-thumb opposition sequence in chronic,
well-recovered subcortical stroke patients. Using independent component
analysis, they could show that recovery of motor function involved
pre-existing cortical networks contributing to recovery in a
differentiated manner.
The study of Abela et al.
complements these investigations of functional networks associated with
recovery in the case of cortical sensorimotor stroke. The structural
covariance network in patients recovering from hand paresis encompassed
(i) a cortico-striato-thalamic loop involved in motor execution and (ii)
higher order sensorimotor cortices affected by the stroke lesions. The
network emerged in the early chronic stage post-stroke was related to
gray matter volume increases in the ipsilesional medio-dorsal thalamus,
and its expression depend on an interaction of recovered hand function
and the lesion size.
Bannister et al.
report about neuroimaging evidence for the significance of the
contralesional hemisphere in the recovery process after hemispheric
supratentorial ischemic stroke, thus supplementing the review of Buetefisch.
They followed the time course of touch sensation in the upper extremity
using resting state – fMRI to explore functional connectivity.
Improvement of touch sensation was related to changes in the
contralesional hemisphere and cerebellum: (1) an increase in
connectivity strength between the secondary somatosensory area seed and
both inferior parietal cortex and middle temporal gyrus as well as the
thalamus seed and cerebellum and (2) a decrease in connectivity strength
between SI seed and the cerebellum.
Primaßin et al.
dealed with four exemplary cases in which motor and language domains
were affected differently. They focused on dissociative outcomes after 7
weeks of rehabilitative treatment following the predominant failure at
baseline. Primarily, precise location of the lesions in the
corticospinal tract and/or fasciculus arcuatus, respectively, turned out
to be critical for recovery. Motor and language improvement seemed to
occur together, rather than to compete for recovery resources.
Ben-Shabat et al.
investigated changes in human proprioception, its specific brain
activation, laterality, and changes following stroke. Brain activation
involved the supramarginal gyrus (SMG) and dorsal premotor cortex (PMd)
with a prominent lateralization in the former. Lateralization was
diminished in three patients exhibiting proprioceptive deficits
post-stroke and a common lesion within the thalamus. The findings
underline the role of SMG and dPM in spatial processing and motor
control.
Brugger et al.
investigated the intriguing role of supplementary motor complex (SMC)
and disturbed motor control, a retrospective clinical and lesion
analysis of 10 patients presenting anterior cerebral artery stroke. In
the very acute phase, alien hand syndrome (AHS) dominated accompanied by
failed conscious awareness of motor intention and a missing sense of
agency while performing externally triggered movements. In the
follow-up, motor signs specifically related to AHS, i.e., disturbed
self-initiated movements, grasping, and intermanual conflict, were
mainly related to lesions of the pre-supplementary motor area and medial
cingulate cortex.
Camilleri et al.
studied the neural substrate underlying the performance of the trail
making test (TMT) that is often used in the follow-up of stroke. In
healthy volunteers, they found that performance in terms of motor speed
to be related to the local brain volume of a region in the lower bank of
the left inferior sulcus. Conjunction analysis of four connectivity
approaches has shown this area to represent a constituent of the
so-called multiple demand network, highlighting the TMT as related
rather to executive than primary motor function.
In summary, the neurological deficits, recovery
mechanisms, and the prognosis for recovery after stroke are hot spots of
clinical neurology and systems neuroscience research. Multimodal
imaging, applied neurophysiology, and careful neurobehavioral in vivo
correlations have opened new vistas on the pathophysiological
mechanisms underlying post-stroke recovery of upper extremity
sensorimotor deficits paving new avenues for future research.
Conflict of Interest Statement
The authors declare that the research was conducted in
the absence of any commercial or financial relationships that could be
construed as a potential conflict of interest.
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