Kyung Jae Yoon

Functional improvement and neuroplastic effects of anodal transcranial direct current stimulation (tDCS) delivered 1day vs. 1week after cerebral ischemia in rats

Transcranial direct current stimulation (tDCS) is an emerging tool for improving recovery from stroke. However, there has been no trial to determine whether it has a therapeutic benefit in the early stage of cerebral ischemia, and there is no consensus on the optimal time window of stimulation. Here, we described the effects of anodal tDCS in early cerebral ischemia, assessing functional improvements and changes in neuronal plasticity, and identifying the optimal time window for delivering tDCS to maximize functional gains. Thirty rats were randomly assigned to three groups: sham (n=10); early tDCS (ET), receiving tDCS 1day after ischemia for 5 days (n=10), and late tDCS (LT), receiving tDCS 1 week after ischemia for 5 days (n=10). Both ET and LT groups showed improved Barnes maze performance and motor behavioral index scores. However, only the LT group exhibited improvement in beam balance test. Immunohistochemical stainings showed that the ET group reinforced notable MAP-2 expression and the LT group enhanced mainly the level of GAP-43 in both peri-lesional and contralesional cortex. These immunohistochemical results had significant correlation with behavioral and cognitive functions. However, brain MRI and (1)H MRS showed no significant differences among the three groups in ischemic volume and metabolic alteration. These results suggest that anodal tDCS has the potential to modulate neural plasticity around the ischemic penumbra and even in the contralesional area without aggravating infarction volume and metabolic alteration. The degree of functional improvement was slightly greater when tDCS was applied 1 week rather than 1 day after ischemic injury.

Ultrasound elastography in the early diagnosis of plantar fasciitis

BACKGROUND The purpose of this study was to investigate whether ultrasound (US) elastography is useful for the early diagnosis of plantar fasciitis. MATERIAL AND METHODS We retrospectively reviewed US elastography findings of 18 feet with a clinical history and physical examination highly suggestive of plantar fasciitis but with normal findings on conventional US imaging as well as 18 asymptomatic feet. RESULT Softening of the plantar fascia was significantly greater in the patient than in the control group [Reviewers 1 and 2: 89% (16/18) vs. 50% (9/18), P=.027, respectively]. CONCLUSION US elastography is useful for the early diagnosis of plantar fasciitis.

BDNF genotype influence the efficacy of rTMS in stroke patients

Brain-derived neurotrophic factor (BDNF) genotype can influence neural response to repetitive transcranial magnetic stimulation (rTMS) in normal individuals. In this study we established personalized stimulus intensity of facilitatory rTMS according to BDNF genotype in stroke patients. Twenty-two chronic stroke patients were enrolled. All patients underwent three different sessions of rTMS over the ipsilesional M1 in randomized order with a washout period exceeding 24h: first condition, high-frequency rTMS with sub-threshold intensity; second condition, high-frequency rTMS with supra-threshold intensity; third condition, sham rTMS. Cortical excitability in the affected hemisphere was assessed with motor evoked potentials (MEPs) before and after stimulation. Data were analyzed according to BDNF genotype. Six [27.3%] and 16 [72.7%] participants were classified in the Val/Val group and Met allele group, respectively. In each group, significant increases were observed in the amplitude of MEPs after the stimulation in the first and second conditions (p<0.05), but not in the third condition. However, a significantly higher increase of amplitude of MEPs was observed between the first and second conditions in only the Val/Val group (p<0.05). BDNF genotype and stimulus intensity should be considered when high-frequency rTMS is used for the modulation of cortical excitability in patients with chronic stroke.

Videofluoroscopic and Manometric Evaluation of Pharyngeal and Upper Esophageal Sphincter Function During Swallowing

Background/Aims The purpose of this study was to determine important manometric metrics for the analysis of pharyngeal and upper esophageal sphincter (UES) function and to investigate the effect of viscosity and other confounding factors on manometric results. Methods Manometric studies were performed on 26 asymptomatic volunteers (12 men and 14 women; age, 19–81 years). The manometric protocol included 5 water swallows (5 mL), 5 barium swallows (5 mL) and 5 yogurt swallows (5 mL). Evaluation of high-resolution manometry parameters including basal pressure of the UES, mesopharyngeal contractile integral (mesopharyngeal CI, mmHg · cm · sec), CI of the hypopharynx and UES (hypopharyngeal CI), relaxation interval of UES, median intrabolus pressure and nadir pressure at UES was performed using MATLAB. Results Mesopharyngeal CIs for barium and yogurt swallows were significantly lower than those for water swallows (both P < 0.05). Hypopharyngeal CIs for water swallows were significantly lower than those for barium swallows (P = 0.004), and median bolus pressure at UES for barium swallows was significantly higher than that for water and yogurt swallows (both P < 0.05). Furthermore, hypopharyngeal CI and median intrabolus pressure at UES were significantly related to age for 3 swallows (all P < 0.01 and P < 0.05, respectively). A significant negative correlation was also noted between nadir pressure at UES and age for water and yogurt swallows (all P < 0.05). Conclusions Manometric measurement of the pharynx and UES varies with respect to viscosity. Moreover, age could be a confounding variable in the interpretation of pharyngeal manometry.

Assessment of Follow-Up Sonography and Clinical Improvement among Infants with Congenital Muscular Torticollis

BACKGROUND AND PURPOSE: Infants grow rapidly, which causes the SCM to thicken physiologically. Therefore some cases of physiologically-thickened SCM can be confused with a poor response to physical therapy. There have been only a few quantitative ultrasonographic studies on the clinical outcome of rehabilitation for CMT. Our aim was to evaluate whether a new sonographic assessment method that uses the muscular thickness ratio of the SCM can help quantify the outcome of rehabilitation therapy for patients with CMT. MATERIALS AND METHODS: We evaluated 48 patients (male/female, 17:31; mean age, 3.9 months) who were diagnosed with CMT and who underwent initial and follow-up sonography. The ratio of the thickness of the involved SCM to the thickness of the intact SCM (SCM thickness ratio) was calculated. A scoring system based on the range of motion of the neck was used to assess clinical improvement. The correlations between clinical improvement and the thickness of the involved muscle, the difference in involved muscle thickness, the SCM thickness ratio, and the difference in the SCM thickness ratio were evaluated with Spearman rank correlations. RESULTS: Follow-up Cheng scores were higher than initial scores; this difference indicates clinical resolution (follow-up, 4.90; initial, 3.38). The SCM thickness ratio at follow-up was lower than that at the initial evaluation (follow-up, 1.29–1.34; initial, 1.65–1.77). Intra- and interobserver agreements were excellent. Most variables were moderately correlated with clinical improvement (correlation coefficients, 0.36–0.509). R1 showed the highest correlation with clinical improvement (0.481 and 0.509), followed by the initial maximal thickness of the SCM (0.434 and 0.488). ΔP (P1–P2) and ΔR showed similar correlation coefficients with clinical improvement. CONCLUSIONS: Measurement of the SCM thickness ratio appears to overcome the problem of a false-positive diagnosis of clinical aggravation of CMT resulting from physiologic growth. R1 and ΔR are accurate objective measurements, which can be used in the management of CMT.

Effects of anodal transcranial direct current stimulation (tDCS) on behavioral and spatial memory during the early stage of traumatic brain injury in the rats.

Transcranial direct current stimulation (tDCS) is a noninvasive technique to modulate the neural membrane potential. Its effects in the early stage of traumatic brain injury (TBI) have rarely been investigated. This study assessed the effects of anodal tDCS on behavioral and spatial memory in a rat model of traumatic brain injury. Thirty six rats underwent lateral fluid percussion and were then randomly assigned to one of three groups: control (n=12), five-day tDCS over peri-lesional cortex at one (1W, n=12), or two (2W, n=12) weeks post-injury. The Barnes maze (BM) and Rotarod (RR) tests were evaluated in a blind manner on day 1, week 3 and week 5 post-injury. After three weeks, both the 1W and 2W groups showed significant improvements in the BM ratio (P<0.05), whereas only group 2W obtained a significant improvement in the RR ratio compared with the control group (P<0.05). However, there were no significant differences between any of the groups at five weeks after TBI. Immunohistochemistry revealed that only group 2W had a significantly higher brain-derived neurotrophic factor (BDNF) expression in the peri-lesional cortex, which was significantly correlated with the improvement of the Rotarod test at 3-week post-injury. However, BDNF expression in the ipsi-lesional hippocampus was not significantly different among the three groups. Group 1W tended to have increased choline/creatine ratios, as measured by magnetic resonance spectroscopy in the peri-lesional cortex, than the control group (P=0.051). Neither regimen aggravated the lesion volume or brain edema measured by MRI. These beneficial effects were not observed with either regimen at five weeks post-injury. In conclusions, anodal tDCS ameliorated behavioral and spatial memory function in the early phase after TBI when it is delivered two weeks post-injury. Earlier stimulation (one week post-injury) improves spatial memory only. However, the beneficial effects did not persist after cessation of the anodal stimulation.

Small Deep Infarction in Patients with Atrial Fibrillation: Evidence of Lacunar Pathogenesis

Background: It is difficult to clarify whether small deep infarction is caused by cardioembolism or intrinsic small vessel disease in patients with atrial fibrillation (AF). The purpose of this study was to determine whether preexisting small vessel disease would differ according to the presenting infarct pattern and to determine the factors associated with acute single small deep infarction in stroke patients with AF. Methods: Between January 2008 and August 2012, 1,592 consecutive patients with acute ischemic stroke presenting within 7 days of symptom onset were entered in a prospectively maintained stroke registry. For the present study, 231 stroke patients with AF were enrolled irrespective of the stroke subtype. We divided these patients into 2 groups (lacunar infarct pattern, n = 20, vs. nonlacunar infarct pattern, n = 211) according to the acute infarct pattern on diffusion-weighted imaging. Patients with acute single small deep infarction on diffusion-weighted imaging were assigned to the lacunar infarct pattern group. We assessed the severity of preexisting small vessel disease by grading white matter lesions (WMLs) according to the Fazekas scale (periventricular WML score ranging from 0 to 3 and deep WML score ranging from 0 to 3 were added to give a total WML score ranging from 0 to 6), multilacunar state (number of chronic lacunes ≥2) and the presence of microbleeds. Demographic characteristics, vascular risk factors and neuroimaging data were compared between the two groups. Results: Patients with a lacunar infarct pattern showed more severe WMLs than those with a nonlacunar pattern [median total WML score 2.5 (range 2-4) vs. 1.0 (0-2); p < 0.001]. A multilacunar state was more prevalent in the lacunar infarct pattern group compared with the nonlacunar pattern group (65 vs. 28.9%; p = 0.001). However, the presence of microbleeds did not differ between the groups. Multiple logistic regression analyses revealed periventricular WMLs [odds ratio (OR) 4.12, 95% confidence interval (CI) 2.14-7.92], deep WMLs (OR 3.42, 95% CI 1.75-6.66) and multilacunar state (OR 7.85, 95% CI 2.45-25.6) as the predictors of a lacunar infarct pattern. Conclusions: The severity of WMLs and chronic lacunes were independent predictors of the incident infarct pattern, which suggested that acute single small deep infarction might be caused by intrinsic small vessel disease despite the presence of concomitant AF.

Ability of High-Resolution Manometry to Determine Feeding Method and to Predict Aspiration Pneumonia in Patients With Dysphagia

Objectives:The introduction of high-resolution manometry (HRM) offered an improved method to objectively analyze the status of pharynx and esophagus. At present, HRM for patients with oropharyngeal dysphagia has been poorly studied. We aimed to determine feeding method and predict the development of aspiration pneumonia in patients with oropharyngeal dysphagia using HRM.Methods:We recruited 120 patients with dysphagia who underwent both HRM and videofluoroscopic swallow study. HRM was used to estimate pressure events from velopharynx (VP) to upper esophageal sphincter (UES). Feeding methods were determined to non-oral or oral feeding according to dysphagia severity. We prospectively followed patients to assess the development of aspiration pneumonia.Results:VP maximal pressure and UES relaxation duration were independently associated with non-oral feeding. Non-oral feeding was determined based on optimal cutoff value of 105.0 mm Hg for VP maximal pressure (95.0% sensitivity and 70.0% specificity) and 0.45 s for UES relaxation duration (76.3% sensitivity and 57.5% specificity), respectively. During a mean follow-up of 18.8 months, 15.8% of patients developed aspiration pneumonia. On multivariate Cox regression analysis, VP maximal pressure (P<0.01) and UES relaxation duration (P<0.05) independently predicted the development of aspiration pneumonia. Cumulative incidence of aspiration pneumonia was significantly increased in patients with readings below optimal cutoff values for VP maximal pressure (P<0.01) and UES relaxation duration (P<0.01), individually.Conclusions:We first established the optimal thresholds for HRM parameters to determine feeding method and predict the development of aspiration pneumonia in patients with oropharyngeal dysphagia.

Comparison of Diffusion Tensor Tractography and Motor Evoked Potentials for the Estimation of Clinical Status in Subacute Stroke

Objective To compare diffusion tensor tractography (DTT) and motor evoked potentials (MEPs) for estimation of clinical status in patients in the subacute stage of stroke. Methods Patients with hemiplegia due to stroke who were evaluated using both DTT and MEPs between May 2012 and April 2015 were recruited. Clinical assessments investigated upper extremity motor and functional status. Motor status was evaluated using Medical Research Council grading and the Fugl-Meyer Assessment of upper limb and hand (FMA-U and FMA-H). Functional status was measured using the Modified Barthel Index (MBI). Patients were classified into subgroups according to DTT findings, MEP presence, fractional anisotropy (FA) value, FA ratio (rFA), and central motor conduction time (CMCT). Correlations of clinical assessments with DTT parameters and MEPs were estimated. Results Fifty-five patients with hemiplegia were recruited. In motor assessments (FMA-U), MEPs had the highest sensitivity and negative predictive value (NPV) as well as the second highest specificity and positive predictive value (PPV). CMCT showed the highest specificity and PPV. Regarding functional status (MBI), FA showed the highest sensitivity and NPV, whereas CMCT had the highest specificity and PPV. Correlation analysis showed that the resting motor threshold (RMT) ratio was strongly associated with motor status of the upper limb, and MEP parameters were not associated with MBI. Conclusion DTT and MEPs could be suitable complementary modalities for analyzing the motor and functional status of patients in the subacute stage of stroke. The RMT ratio was strongly correlated with motor status.

Right-side propensity of cardiogenic emboli in acute ischemic stroke with atrial fibrillation.

Abstract Objectives. We attempted to determine the propensity for sidedness of cardiogenic emboli associated with atrial fibrillation (AF) by comparing the sides on which microembolic signals (MES) were detected via transcranial Doppler (TCD) monitoring and the location of infarcts on magnetic resonance imaging. Design. Patients with AF on Holter monitoring and MES on TCD monitoring were selected from an ischemic stroke registry. Patients with prosthetic valves or cerebral/carotid artery stenosis were excluded. Results. By TCD monitoring of 30 patients, 78 MES were detected: 47 on the right and 31 on the left side (60.3% vs. 39.7%, p < 0.01, chi-square test). Among 21 patients who had middle or anterior cerebral artery (MCA/ACA) territory infarcts, 16 had right-side-dominant infarcts and 5 patients had left-side-dominant infarcts (76.2% vs. 23.8%, p < 0.01, chi-square test). The median infarct volume on the right side was 16.2 (3.18–75.4) ml, while that of left side was 1.2 (0.25–5.05) ml (p < 0.01, Mann–Whitney U test). Conclusion. This study demonstrated the existence of a right-side propensity of cardiogenic emboli and the larger infarct volume of right-side MCA/ACA stroke in patients with AF. These results can be attributed to anatomical differences between the innominate and the left common carotid artery.