Youngkook Kim

Background: Corticospinal tract (CST) integrity is a well-established imaging correlate of post-stroke motor outcome but does not fully explain interindividual variability, particularly in moderate-to-severe impairment. The corpus callosum (CC) may provide complementary structural information. This study examined whether early subacute callosal microstructure is associated with upper limb motor outcome and recovery. Methods: We retrospectively analyzed 38 patients with moderate-to-severe middle cerebral artery stroke who underwent diffusion tensor imaging during the early subacute phase. Fractional anisotropy (FA) values of the CST and CC were obtained. Upper limb motor function was assessed using the Shoulder Abduction and Finger Extension (SAFE) score. Simple linear regression and hierarchical multiple linear regression analyses examined associations of corrected CC FA (CC-FA ~ corrected~) with SAFE scores and ΔSAFE (change in SAFE score from baseline to 6 months). Results: CST FA laterality index (CST FALI), lesion volume, and CC-FA ~ corrected~ were significantly associated with SAFE scores at 3 and 6 months post-stroke. In hierarchical multiple regression models, CC-FA ~ corrected~ of the genu showed a consistent nominal incremental contribution beyond CST FALI, age, and lesion volume at both timepoints (3 months: ΔR ² = 0.061, adjusted R ² = 0.600; 6 months: ΔR ² = 0.065, adjusted R ² = 0.646), though these findings require confirmation in larger prospective cohorts. The body and splenium did not reach statistical significance after accounting for these covariates. In exploratory analysis, CC-FA ~ corrected~ of the genu was the only variable significantly associated with ΔSAFE (R = 0.396, p = 0.041); CST FALI was not ( p = 0.097). Conclusion: CC-FA ~ corrected~ of the genu showed a consistent nominal association with upper limb motor outcome beyond CST integrity in moderate-to-severe stroke, suggesting a complementary role of callosal microstructure alongside CST integrity, with an exploratory association also observed for the magnitude of motor improvement over time. Early combined assessment of CC and CST integrity during the subacute phase may provide preliminary information regarding post-stroke motor outcomes.

Kim S, et al. Brain Neurorehabil. 2026 Jul;19(2):e13. https://doi.org/10.12786/bn.2026.19.e13

Background: Unilateral hemispheric stroke can impair the ipsilesional motor performance, which is crucial for attaining optimal functional outcomes poststroke. However, the specific brain structures contributing to ipsilesional motor performance impairment remain unclear. Objective: To explore the link between ipsilesional motor performance and the microstructural integrity of relevant neural pathways. Methods: This study enrolled 60 consecutive patients in the early subacute phase of stroke recovery. Ipsilesional motor performance was assessed using the Box and Block Test. Multiple linear regression was used to evaluate the associations between ipsilesional motor performance and the microstructural integrity of relevant white matter tracts (Biomarker models) and cognitive function test scores (Cognition models). Results: Biomarker models, including the genu of the corpus callosum, ipsilesional cingulum, fornix, uncinate fasciculus, superior longitudinal fasciculus, and contralesional inferior longitudinal fasciculus, showed a significant association with ipsilesional motor performance. Cognition models, including Mini-Mental State Examination and Trail Making Test-B, were significantly associated with ipsilesional motor performance. Final regression models (combined Cognition and Biomarker models) revealed that the performance time of Trail Making Test-B, in combination with biomarkers, including the genu of the corpus callosum, ipsilesional superior longitudinal fasciculus, and ipsilesional cingulum, predicted ipsilesional motor performance with high explanatory power ( adjusted R ² = .721, .709, and .696, respectively). Conclusions: This study demonstrated that executive function is associated with poststroke ipsilesional motor performance, as evidenced by the microstructural biomarkers involved in executive function. Our findings highlight that the comprehensive role of cognitive functioning rather than the motor system is closely linked to poststroke ipsilesional motor performance.

Park E, et al. Brain Neurorehabil. 2024 Mar;17(1):e9. https://doi.org/10.12786/bn.2024.17.e9

Objective: Dysphagia is a common clinical condition characterized by difficulty in swallowing. It is sub-classified into oropharyngeal dysphagia, which refers to problems in the mouth and pharynx, and esophageal dysphagia, which refers to problems in the esophageal body and esophagogastric junction. Dysphagia can have a significant negative impact one’s physical health and quality of life as its severity increases. Therefore, proper assessment and management of dysphagia are critical for improving swallowing function and preventing complications. Thus a guideline was developed to provide evidence-based recommendations for assessment and management in patients with dysphagia. Methods: Nineteen key questions on dysphagia were developed. These questions dealt with various aspects of problems related to dysphagia, including assessment, management, and complications. A literature search for relevant articles was conducted using Pubmed, Embase, the Cochrane Library, and one domestic database of KoreaMed, until April 2021. The level of evidence and recommendation grade were established according to the Grading of Recommendation Assessment, Development and Evaluation methodology.Results: Early screening and assessment of videofluoroscopic swallowing were recommended for assessing the presence of dysphagia. Therapeutic methods, such as tongue and pharyngeal muscle strengthening exercises and neuromuscular electrical stimulation with swallowing therapy, were effective in improving swallowing function and quality of life in patients with dysphagia. Nutritional intervention and an oral care program were also recommended. Conclusion: This guideline presents recommendations for the assessment and management of patients with oropharyngeal dysphagia, including rehabilitative strategies.

BACKGROUND: The structural integrity of the corticospinal tract (CST) is an important biomarker of poststroke upper limb recovery. Injured CST undergoes Wallerian degeneration rostrocaudally during the first few months. However, there is no standardized measurement of the structural integrity of the CST. This study aimed to determine the measurement accuracy of the structural integrity of the CST. METHODS: This cross-sectional study included 50 consecutive patients with middle cerebral artery stroke who underwent diffusion tensor imaging upon transfer from the acute stroke unit to the inpatient rehabilitation facility (2018–2022). We evaluated hemiplegic upper limb function using Shoulder Abduction and Finger Extension (SAFE) scores. Fractional anisotropy values representing the structural integrity of the CST were evaluated using 4 region of interest-based and 2 tract-based measurements, including the posterior limb of internal capsule, cerebral peduncle, pons, pontomedullary junction, entire CST, and CST in the brainstem. Multivariate linear regression models and the area under the curve (AUC) were used to determine measurement accuracy for hemiplegic upper limb function. RESULTS: The structural integrity of the CST at the pontomedullary junction showed the highest explanatory power, followed by the entire CST, in the multivariate linear regression models (adjusted R ² = 0.459 and 0.425, respectively). The structural integrity of the CST at the pontomedullary junction also showed the highest AUC, followed by the entire CST, in discriminating patients with a SAFE score of <8 or 5 from those with SAFE ≥8 or 5 (SAFE <8: AUC, 0.90 [95% CI, 0.80–1.00]; AUC, 0.83 [0.66–0.99]; SAFE <5: AUC, 0.87 [0.77–0.96]; AUC, 0.83, [0.72–0.95], respectively). CONCLUSIONS: The structural integrity of the CST measured at the pontomedullary junction or entire CST demonstrated the highest accuracy for hemiplegic upper limb function in the subacute phase of stroke.

Background: The cerebellum plays a crucial role in functional movement by influencing sensorimotor coordination and learning. However, the effects of cortico-cerebellar connectivity on the recovery of upper extremity motor function after stroke have not been investigated. We hypothesized that the integrity of the cortico-cerebellar connections would be reduced in patients with a subacute middle cerebral artery (MCA) stroke, and that this reduction may help to predict chronic upper extremity motor function. Methods: We retrospectively analyzed the diffusion-tensor imaging of 25 patients with a subacute MCA stroke (mean age: 62.2 ± 2.7 years; 14 females) and 25 age- and sex-matched healthy controls. We evaluated the microstructural integrity of the corticospinal tract (CST), dentatothalamocortical tract (DTCT), and corticopontocerebellar tract (CPCT). Furthermore, we created linear regression models to predict chronic upper extremity motor function based on the structural integrity of each tract. Results: In stroke patients, the affected DTCT and CST showed significantly impaired structural integrity compared to unaffected tracts and the tracts in controls. When all models were compared, the model that used the fractional anisotropy (FA) asymmetry indices of CST and DTCT as independent variables best predicted chronic upper extremity motor function ( R² = .506, P = .001). The extent of structural integrity of the CPCT did not significantly differ between hemispheres or groups and was not predictive of motor function. Conclusions: We found evidence that microstructural integrity of the DTCT in the subacute phase of an MCA stroke helped to predict chronic upper extremity motor function, independent of CST status.

Training‐induced plasticity by practicing expert skills has been of particular interest; however, little is known about white matter plasticity for improving a fundamental element of body function, such as balance or postural control. This study explored white matter plasticity in nonexpert healthy adults, based on stepwise balance training. Seventeen participants were included and performed a home‐based balance training program for 4 weeks (30 min/day, 3 days/week). Before commencing training, they underwent a baseline diffusion tensor imaging scan. A second scan was acquired at the end of the 4‐week training. Lateralised balance load was applied on the right leg to contrast any lateralised effect on the white matter tracts. The balance function was assessed using the Community Balance & Mobility Scale. We examined changes in the fractional anisotropy values of the tracts of interest between pre‐ and post‐training. After the 4‐week training, the fractional anisotropy values were enhanced in the right superior cerebellar peduncle, transverse pontine fibre, body of the corpus callosum, left fornix and left uncinate fasciculus. The Community Balance & Mobility Scale score improved after 4‐week training, but an association with changes in fractional anisotropy values cannot be evaluated due to the ceiling effect of the balance assessment tools. Balance training can strengthen the cerebro‐cerebellar and interhemispheric structural connections and induce microstructural changes in the limbic structures, including the fornix and uncinate fasciculus. The effect of a lateralised balance load could be projected to the specific white matter tracts in a lateralised manner.

This study analyzed a digitized database of electronic medical records (EMRs) to identify risk factors for post-stroke infections. The sample included 41,236 patients hospitalized with a first stroke diagnosis (ICD-10 codes I60, I61, I63, and I64) between January 2011 and December 2020. Logistic regression analysis was performed to examine the effect of clinical variables on post-stroke infection. Multivariable analysis revealed that post-stroke infection was associated with the male sex (odds ratio [OR]: 1.79; 95% confidence interval [CI]: 1.49–2.15), brain surgery (OR: 7.89; 95% CI: 6.27–9.92), mechanical ventilation (OR: 18.26; 95% CI: 8.49–44.32), enteral tube feeding (OR: 3.65; 95% CI: 2.98–4.47), and functional activity level (modified Barthel index: OR: 0.98; 95% CI: 0.98–0.98). In addition, exposure to steroids (OR: 2.22; 95% CI: 1.60–3.06) and acid-suppressant drugs (OR: 1.44; 95% CI: 1.15–1.81) increased the risk of infection. On the basis of the findings from this multicenter study, it is crucial to carefully evaluate the balance between the potential benefits of acid-suppressant drugs or corticosteroids and the increased risk of infection in patients at high risk for post-stroke infection.