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To investigate the global functional reorganization of the brain following spinal cord injury with graph theory based approach by creating whole brain functional connectivity networks from resting state-functional magnetic resonance imaging (rs-fMRI), characterizing the reorganization of these networks using graph theoretical metrics and to compare these metrics between patients with spinal cord injury (SCI) and age-matched controls.
Twenty patients with incomplete cervical SCI (14 males, 6 females; age, 55±14.1 years) and 20 healthy subjects (10 males, 10 females; age, 52.9±13.6 years) participated in this study. To analyze the characteristics of the whole brain network constructed with functional connectivity using rs-fMRI, graph theoretical measures were calculated including clustering coefficient, characteristic path length, global efficiency and small-worldness.
Clustering coefficient, global efficiency and small-worldness did not show any difference between controls and SCIs in all density ranges. The normalized characteristic path length to random network was higher in SCI patients than in controls and reached statistical significance at 12%-13% of density (p<0.05, uncorrected).
The graph theoretical approach in brain functional connectivity might be helpful to reveal the information processing after SCI. These findings imply that patients with SCI can build on preserved competent brain control. Further analyses, such as topological rearrangement and hub region identification, will be needed for better understanding of neuroplasticity in patients with SCI.
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To delineate whether cortical plasticity induced by continuous theta burst stimulation (cTBS) differed according to catechol-O-methyltransferase (
Eighteen healthy older volunteers (mean age 73.78±5.04; 12 females and 6 males) were recruited. Volunteers randomly assigned in either a sham-first or real cTBS first group participated in two separate TMS visits with at least a 2-day wash-out period. Genotyping was carried out at baseline by a separate researcher who was blinded. cTBS was delivered in a hot spot over M1 at an active motor threshold of 80%. Motor evoked potentials (MEPs) were obtained at 120% of the resting motor threshold before and after sham/cTBS.
The relative MEP to baseline was significantly decreased 0 and 10 minutes post-stimulation and increased 40 minutes post-stimulation, as compared with the sham condition. Immediately after cTBS, the Val/Val group had a significantly reduced relative MEP value, as compared with the MET carrier group.
In healthy older persons, cTBS-induced motor plasticity was reduced in the COMT Val/Val group as compared with the 158Met carrier group.
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To investigate the effect of brain-derived neurotrophic factor (BDNF) Val66Met polymorphism on the recovery after subcortical stroke, using the modified Rankin Scale (mRS).
Subcortical stroke patients with copies of BDNF Val66Met polymorphism (n=7) were compared to their controls (n=7) without a copy of BDNF Val66Met polymorphism after matching for initial severity, location and type of stroke. The mRS scores at 1 and 3 months after discharge from the neurorehabilitation unit were compared between the groups.
A repeated measures ANOVA for mRS revealed significant interaction between time and group (F(2, 24) =37.2, p<0.001) and a significant effect of time (F(2, 24)=10.8, p<0.001), thereby reflecting significant differences between the Met allele (+) group and the Met allele (-) group. There was a significant difference in mRS scores at 3 months post-discharge between the two groups (p=0.01) although no difference was evident in mRS scores at 1 month post-discharge between the two groups. There were significant improvements between mRS scores on admission and mRS scores at 1 month post-discharge (p=0.02), and between mRS scores at 1 month post-discharge and mRS scores at 3 months post-discharge (p=0.004) in the Met allele (-) group.
BDNF Val66Met polymorphism may be associated with worse functional outcome in Korean patients with subcortical stroke. Therefore, BDNF Val66Met polymorphism should be considered as an important prognostic factor for recovery and responses to rehabilitation therapies after stroke in Korean patients. There is a need for developing different rehabilitation strategies for the population with BDNF Val66Met polymorphism. Further studies assessing different outcomes for various functional domains of stroke recovery are needed to clarify the role of BDNF Val66Met polymorphism.
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Method: The protocol for HAT consisted of consecutive 10 days in which a child and his/her caregiver were held in 1.3 atm hyperbaric air chamber for 60 minutes per one day. Nine children with cerebral palsy underwent 99mTc-HMPAO single-photon emission computed tomography (SPECT) before and after HAT. The change of regional cerebral blood flow (rCBF) was evaluated by subtraction analysis using statistical parametric mapping.
Results: Average gestational age and birth weights were 34.0⁑5.1 months, and 2.3⁑1.2 kg, respectively. Two spastic quadriplegics, four spastic diplegics, two spastic hemiplegics, and one ataxic child were enrolled. In 3 out of 9 children, rCBF change was demonstrated; increased perfusion in right cerebellar hemisphere in child with diffuse brain atrophy and increased perfusion in diffuse cerebral cortex in child with left frontal leukoencephalopathy and decreased perfusion of right frontal cortex in child with right frontal leukoencephalopathy.
Conclusion: These findings suggest that HAT may recruit less excitable neurons that was of functionally silent in motor cortex, previously. However, increased rCBF following HAT protocol could not be ruled out whether the result of learning effects or HAT. (J Korean Acad Rehab Med 2003; 27: 335-339)
Objective: The aim of this study is to identify the ipsilateral motor evoked potentials (iMEPs) from unaffected cerebral hemisphere after stroke via transcranial magnetic stimulation, especially in acute stage (within 1 week from attack), and to evaluate the characteristics of iMEPs compared with the crossed contralateral motor evoked potentials (cMEPs).
Method: Thirty patients were recruited, who had suffered their first ischemic stroke and consequent motor deficits and mean duration from attack to examination was 6.0⁑3.3 days. They were tested with round coil stimulator in order to record motor evoked potentials from both contralateral and ipsilateral abductor pollicis brevis (APB) muscles. For the purpose of hand motor cortex mapping, we designed specialized cap, which was marked using international 10∼20 systems by 1 cm interval. In addition, we observed the changes in onset latency and amplitude of MEPs during the isometric contraction of thenar muscle guided by visual and auditory feedback.
Results: iMEPs were generally absent in normal subjects, but they were obtained in 17 (56.7%) of 30 patients by stimulating the unaffected hemisphere. Different from contralateral MEPs, ipsilateral MEPs were obtained with higher stimulation intensity, significantly delayed latencies and lower amplitudes. And we noticed shorter latencies and larger amplitudes of MEPs by the isometric contraction of thenar muscle.
Conclusion: Our results will reflect the compensatory role by the unaffected cerebral hemisphere with respect to motor recovery, if contralateral route is damaged. We provided neurophysiologic evidences of cerebral neuroplasticity, proven by the ipsilateral unaffected hemispheric activation in early phase stroke patients.
The aim of this study is to investigate the mechanism of motor recovery using both functional Magnetic Resonance Imaging (fMRI) and Transcranial Magnetic Stimulation (TMS) in a patient with hemorrhagic contusion on the right basal ganglia area. Functional MRI showed that the left primary sensorimotor cortex and the supplementary motor area were activated when the right fingers performed the flexion-extension exercise. On the other hand, the bilateral primary sensorimotor cortex and the left premotor area were activated with the excerise of left hand. Brain mapping for both abductor pollicis brevis muscles (APB) using TMS revealed that ipsilateral motor evoked potentials (MEPs) were obtained at left APB. Ipsilateral MEPs of left APB showed delayed latency and lower amplitude compared to that of right APB when stimulated at the left motor cortex. We concluded that ipsilateral motor pathway from undamaged motor cortex seems to contribute to the motor recovery in this patient and combining TMS with fMRI may provide a powerful tool for investigating the mechanism of motor recovery.
The present study was designed to investigate the effects and action mechanism of electrical stimulation on functional recovery following spinal cord injury in Sprague-Dawley rats. Electrical stimulation with 0.2 ms, 20 Hz, 1-3 V was applied to the sciatic nerve for 4 hours/day during 6 days following dorsal hemisection of the T10 spinal cord. After 7 days of spinal cord injury, mechanical properties of muscle contraction including contraction time, half relaxation time, maximum twitch tension, maximum tetanic tension, and fatigue index were measured in the soleus and medial gastrocnemius muscles, and the number of c-fos immunoreactive cells was counted in the upper lumbar cord. In mechanical properties of muscle contraction of normal rats, contraction time and half relaxation time of the soleus muscle were 1.5 times and 2 times as long as those of the medial gastrocnemius muscle, respectively. And fatigue index of the soleus muscle was 0.19⁑0.4 and the medial gastrocnemius muscle was 0.82⁑0.03. According to the above characteristics, the soleus muscle was mainly composed of slow muscle fibers and the medial gastrocnemius muscle was composed of fast muscle fibers. Maximum twitch tension, maximum tetanic tension, and fatigue index of both muscles following spinal cord injury were decreased significantly compared to the control group (p<0.01). In electrically stimulated rats following spinal cord injury, maximum twitch tension, maximum tetanic tension, and fatigue index were significantly increased compared to spinal cord injured rats. The number of c-Fos immunoreactive cells was increased markedly at the upper lumbar cord in electrically stimulated rats.
These results may suggest that electrical stimulation not only prevents from muscle atrophy in slow and fast muscles through efferent nerve fibers, but also promotes functional plasticity through afferent nerve fibers by activating silent synapse and regulation of receptors for neurotransmitters.
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