Han Uk Ryu

Microbubble signal and trial of org in acute stroke treatment (TOAST) classification in ischemic stroke

PURPOSE Right-to-left shunt (RLS) through a patent foramen ovale (PFO) is likely associated with ischemic stroke. Many studies have attempted to demonstrate the association between RLS and ischemic stroke. However, information on the association between the degree of RLS and the subtypes of ischemic stroke categorized by the Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification is lacking. METHOD This was a retrospective study involving 508 patients with ischemic stroke who underwent a transcranial Doppler (TCD) microbubble test between 2013 and 2015. The degree of RLS was divided into 4 grades according to the microbubble signal (MBS) as follows: no MBS, grade 1; MBS < 20, grade 2; MBS > 20, grade 3; curtain sign, grade 4. The degree of RLS and the type of ischemic stroke as classified by TOAST were analyzed and compared with other clinical information and laboratory findings. RESULTS The higher RLS grade was associated with the cardioembolism (CE) and stroke of undetermined etiology (SUE), and the microbubble signals were inversely related with small vessel disease (SVD). An MBS higher than grade 3 showed a 2.95-fold higher association with SUE than large artery atherosclerosis (LAA), while grade 4 MBS revealed an approximately 8-fold higher association with SUE than LAA. CONCLUSION RLS identified by the TCD microbubble test was significantly and independently associated with cryptogenic ischemic stroke (negative evaluation). Subsequent studies are needed to determine the biologic relationship between RLS and ischemic stroke, particularly the cryptogenic subtype of ischemic stroke.

Identification of Cerebral Artery Stenosis Using Bilateral Photoplethysmography

Cerebral artery stenosis is currently diagnosed by transcranial Doppler (TCD), computed tomographic angiography (CTA), or magnetic resonance angiography (MRA). CTA exposes a patient to radiation, while CTA and MRA are invasive and side effects were related to contrast medium use. This study aims to provide a technique that can simply discriminate between people with normal blood vessels and those with cerebral artery stenosis using photoplethysmography (PPG), which is noninvasive and inexpensive. Moreover, the measurement takes only 120 seconds and is conducted on the fingers. The technique projects the light of a specific wavelength and analyzes the pulse waves which are generated when the blood passes through the blood vessels according to ones heartbeat using the transmitted light. Normalization was performed after dividing the extracted pulse waveform into windows, and maximum positive and negative amplitudes (MPA, MNA) were extracted from the detected pulse waves as features. The extracted features were used to identify normal subjects and those with cerebral artery stenosis using a linear discriminant analysis. The study results showed that the recognition rate using MPA was 92.2%, MNA was 90.6%, and combined MPA + MNA was 90.6%. The technique proposed is expected to detect early stage asymptomatic cerebral artery stenosis and help prevent ischemic stroke.

Opsoclonus-myoclonus syndrome following long-term use of cyclosporine

Abstract Background: Cyclosporine A (CsA) is a widely used immunosuppressive agent that may provoke unexpected neurologic complications. The mechanism is unclear and variable intervals have been reported between CsA administration and onset of the related side effects. Here, we describe a case of delayed-onset CsA neurotoxicity presenting as opsoclonus-myoclonus syndrome (OMS). Case details: A 37-year-old woman with a two-week period of opsoclonus and upper extremity myoclonus was admitted to our hospital. The patient had been taking CsA for 17 years after receiving a kidney transplant. Further evaluation did not reveal any other abnormalities. Seven days after switching from CsA to tacrolimus, in the absence of additional immune-modulating therapy, her neurologic symptoms improved considerably. Conclusion: This is the case of delayed, long-term complications of CsA presenting as OMS. Symptoms resolved by substituting CsA with another immunomodulating drug. The etiology of the neurologic complications may involve paradoxically-enhanced delayed-type hypersensitivity.

Direct Assessment of Wall Shear Stress by Signal Intensity Gradient from Time-of-Flight Magnetic Resonance Angiography

The aim of the study was to calculate the arterial wall signal intensity gradient (SIG) from time-of-flight MR angiography (TOF-MRA) and represent arterial wall shear stress. We developed a new algorithm that uses signal intensity (SI) of a TOF-MRA to directly calculate the signal intensity gradient (SIG). The results from our phantom study showed that the TOF-MRA SIG could be used to distinguish the magnitude of blood flow rate as high (mean SIG ± SD, 2.2 ± 0.4 SI/mm for 12.5 ± 2.3 L/min) and low (0.9 ± 0.3 SI/mm for 8.5 ± 2.6 L/min) in vessels (p < 0.001). Additionally, we found that the TOF-MRA SIG values were highly correlated with various flow rates (β = 0.96, p < 0.001). Remarkably, the correlation coefficient between the WSS obtained from the computational fluid dynamics (CFD) analysis and the TOF-MRA SIG was greater than 0.8 in each section at the carotid artery (p < 0.001 for all β values). This new technique using TOF-MRA could enable the rapid calculation of the TOF-MRA SIG and thereby the WSS. Thus, the TOF-MRA SIG can provide clinicians with an accurate and efficient screening method for making rapid decisions on the risk of vascular disease for a patient in clinical practice.

Intermittent Theta Slowings in Contralateral Side of Weakness after Sleep Deprivation on Spot EEG in Sporadic Hemiplegic Migraine

Hemiplegic migraine (HM) is an uncommon type of migraine which is classified into sporadic and familial subtype. The noticed electroencephalogram (EEG) findings during HM attack are diffuse slowing contralateral to the weakened limb, but are usually normal in asymptomatic states. A 52-year-old woman who suffered from headache accompanying right arm weakness and aphasic symptoms admitted to our hospital. She underwent total five times of EEG including 2 times before admission. Only the last EEG exam after 24 hours of sleep deprivation (SD) showed intermittent slowing and higher amplitude of positive occipital sharp transients (POSTs) on the left parieto-occipital area. Here, we report a case with HM who revealed abnormal EEG findings after SD, which was not observed in the routine EEG study without SD.