Chul Ho Sohn

Review of the Current Status of Intra-Arterial Thrombolysis for Treating Acute Cerebral Infarction: a Retrospective Analysis of the Data from Multiple Centers in Korea

Objective The purpose of the study was to review the current status of intra-arterial (IA) thrombolysis in Korea by conducting a retrospective analysis of the data from multiple domestic centers. Materials and Methods The radiologists at each participating institution were asked to fill out case report forms on all patients who had undergone IA recanalization due to acute anterior circulation ischemia. These forms included clinical, imaging and procedure-related information. A central reader analyzed the CT/MR and angiographic results. The rates of successful recanalization, hemorrhagic transformation and functional outcome were obtained. The univariate analyses were performed together with the multivariate analysis. Results We analyzed the data from 163 patients, and they had been treated at seven institutes. The initial imaging modalities were CT for 46 patients (28%), MR for 63 (39%), and both for 54 (33%). Various mechanical treatment methods were applied together in 50% of the patients. Radiologically significant hemorrhage was noted in 20/155 patients (13%). We found various factors that influenced the recanalization rate and the occurrence of significant hemorrhagic transformations. The favorable outcome rate, reported as modified Rankin Scale ≤ 2, was 40%, and the mortality rate was 11%. The factors that predicted a poor functional outcome were old age (p = 0.01), initially severe neurological symptoms (p < 0.0001), MR findings of a wide distribution of lesions (p = 0.001), involvement of the basal ganglia (p = 0.01), performance of procedures after working hours (p = 0.01), failure of recanalization (p = 0.003), contrast extravasation after the procedure (p = 0.007) and significant hemorrhagic transformation (p = 0.002). The subsequent multivariate analysis failed to show any statistically significant variable. Conclusion There was a trend toward increased dependency on MR imaging during the initial evaluation and increased usage of combined pharmacologic/mechanical thrombolysis. The imaging and clinical outcome results of this study were comparable to those of the previous major thrombolytic trials.

Functional Reorganization in Chronic Hemiparetic Patients after Training: fMRI Studies

The aim of this study was to evaluate effects of short-term repetitive-bilateral exercise on the activation of motor network using functional magnetic resonance imaging (fMRI). Eight control subjects and four chronic hemiparetic patients were investigated for the present study. The training program with a symmetrical upper-limb motion trainer was performed at 1 hr/day, 5 days/week during 6 weeks. Fugl-Meyer assessments (FMA) were performed every two weeks during the training. We compared cerebral and cerebellar cortical activations in two different tasks before and after the training program: (1) the only unaffected hand movement (Task 1), and (2) passive movements of the affected hand by the active movement of the unaffected hand (Task 2). fMRI was performed at 3T with wrist flexion-extension movement at 1 Hz during the motor tasks. All patients showed significant improvements of FMA scores in their paretic limbs after training. fMRI studies in Task 1 showed that cortical activations decreased in ipsilateral SMC but increased in contralateral sensorimotor cortex (SMC) and ipsilateral cerebellum (CRB). Task 2 showed cortical reorganizations in bilateral SMC, pre-motor area (PMA), supplementary area (SMA) and CRB. This study demonstrated that plastic changes of motor network occurred as a neural basis of the improvement subsequent to repetitive-bilateral exercises using the symmetrical upper-limb motion trainer.

Diffusion Tensor Imaging in Patients with Thalamic Hemorrhage: Correlations between Diffusion Anisotropy and Motor Recovery

Diffusion tensor imaging (DTI) provides quantitative information in the magnetic resonance imaging on the diffusion anisotropy about the integrity of white matter tracts. The aim of this study was to measure diffusion anisotropy and to correlate with upper-limb motor recovery in four chronic hemiparetic patients with thalamic hemorrhage. Fractional anisotropy (FA) was measured in the posterior limb of internal capsules (IC) in the affected side and in the corresponding contralateral normal side before and after 6 week motor training. The correlation between motor recovery of the affected hand and the ratio of FAs of the affected side and the contralateral normal side were investigated. Both FA ratio and motor function significantly increased after the training. A significant correlation was found between motor recovery and FA in the posterior limb of IC. The degree of impairment in diffusion anisotropy of hemiparetic patients might be helpful in prognosis of the motor function.