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Dong-Wha Kang

Publications and source records attributed to Dong-Wha Kang.

27 records · Page 2Linked to original sources
PubMed2004

Multiple cerebral microbleeds: MRI marker of a diffuse hemorrhage-prone state.

BACKGROUND: Recent reports have indicated that cerebral microbleeds (CMBs) detected on gradient-echo (GRF) magnetic resonance imaging may be a risk factor for therapy related intracranial hemorrhages (ICHs). CASE DESCRIPTION: The authors describe 3 patients with multiple CMBs in whom ICHs occurred either after tissue plasminogen activator administration or after the initiation of antiplatelet therapy. Hemorrhages occurred in brain areas with normal appearances on GRE imaging and remote from the CMBs. CONCLUSION: Multiple CMBs may signal a diffuse hemorrhage-prone vasculopathy.

Aged↗
PubMed2003

Association of ischemic lesion patterns on early diffusion-weighted imaging with TOAST stroke subtypes.

BACKGROUND: Different topographic patterns in patients who experience an acute ischemic stroke may be related to specific stroke causes. OBJECTIVE: To determine if lesion patterns on early diffusion-weighted imaging (DWI) are associated with stroke subtypes determined by the TOAST (Trial of ORG 10172 in Acute Stroke Treatment) classification. DESIGN: Cross-sectional study. SETTING: General community hospital. Patients We studied 172 consecutive ischemic stroke patients with a symptomatic lesion on DWI performed within 24 hours of stroke onset. MAIN OUTCOME MEASURES: Lesion patterns on DWI were classified into single lesions (corticosubcortical, cortical, subcortical > or =15 mm, or subcortical <15 mm), scattered lesions in one vascular territory (small scattered lesions or confluent with additional lesions), and multiple lesions in multiple vascular territories (in the unilateral anterior circulation, in the posterior circulation, in bilateral anterior circulations, or in anterior and posterior circulations). RESULTS: We found an overall significant relationship between DWI lesion patterns and TOAST stroke subtypes (P<.001). Corticosubcortical single lesions (P =.01), multiple lesions in anterior and posterior circulations (P =.03), and multiple lesions in multiple cerebral circulations (P =.008) were associated with cardioembolism. Multiple lesions in the unilateral anterior circulation (P =.04) and small scattered lesions in one vascular territory (P =.06) were related to large-artery atherosclerosis. Nearly half (11/23) of the patients with a single subcortical lesion that was 15 mm or larger were classified as having cryptogenic strokes (P =.001), although 9 of these patients had a classic lacunar syndrome without cortical hypoperfusion. CONCLUSIONS: Early DWI lesion patterns are associated with specific stroke causes. Conventional 15-mm criteria for lacunes, however, may underestimate the diagnosis of small-vessel occlusion with DWI.

Adult↗
PubMed2003

Early ischemic lesion recurrence within a week after acute ischemic stroke.

Previous observations suggested that multiple ischemic lesions on diffusion-weighted imaging (DWI) are common in acute stroke patients. We hypothesized that a source of these multiple lesions was the recurrence of ischemic lesions within a week after a clinically symptomatic stroke. We analyzed 99 acute ischemic stroke patients scanned within 6 hours of onset and at subsequent times within the first week. Ischemic lesion recurrence was defined as any new lesion separate from the index lesion. Recurrent lesions occurring outside initial perfusion deficit were termed 'distant lesion recurrence'. We estimated the hazard ratio (HR) of recurrence associated with clinical and imaging characteristics using log-rank test. Any lesion recurrence was found in 34%, with distant lesion recurrence in 15%, while clinical recurrence was evident in 2%. Initial multiple DWI lesions were associated with any lesion recurrence (HR, 2.83; 95% confidence interval [CI], 1.65-10.29; p = 0.002) and with distant lesion recurrence (HR, 5.99; 95% CI, 4.05-64.07; p < 0.0001). Large-artery atherosclerosis was the most frequent stroke subtype associated with any lesion recurrence (p = 0.026). These results may indicate a prolonged state of increased ischemic risk over the first week and suggest DWI as a possible surrogate measure for recurrent stroke.

Acute Disease↗
PubMed2002

Diffusion-weighted imaging abnormalities in wernicke encephalopathy: reversible cytotoxic edema?

BACKGROUND: Wernicke encephalopathy (WE) is a metabolic disorder of the central nervous system resulting from vitamin B(1) deficiency. The exact mechanisms underlying the pathogenesis of the lesions in WE are not completely understood. Vitamin B1 deficiency is associated with intracellular and extracellular edema by glutamate(N-methyl-D-aspartate) receptor-mediated excitotoxicity. Conventional magnetic resonance imaging (MRI) cannot differentiate the types of edema. Diffusion-weighted imaging (DWI) has been reported to detect early ischemic damage (cytotoxic edema) as bright areas of high signal intensity (SI) and vasogenic edema as areas of heterogeneous SI. OBJECTIVES: To describe the DWI findings and to characterize the types of edema in WE using DWI. SETTING: Tertiary referral center. DESIGN AND METHODS: Two patients with WE underwent DWI and conventional MRI with gadolinium enhancement. Wernicke encephalopathy was diagnosed with salient conventional MRI findings (high SIs in the paramedian thalamus, periaqueductal gray matter, and mamillary bodies) and typical clinical history and symptoms. Apparent diffusion coefficient (ADC) values were measured in abnormal lesions by visual inspection of DWIs and T2-weighted echo planar images. RESULTS: T2-weighted and fluid-attenuated inversion recovery MRIs showed high SIs in the bilateral paramedian thalamus, mamillary bodies, and periaqueductal gray matter. The DWIs showed bright high SI in the corresponding lesions, and ADC values were decreased (patient 1: 512-545 x 10(-6)mm2/s; patient 2: 576-612 x 10(-6)mm2/s). The ADC decrease and the DWI high SI were normalized in 2 weeks with administration of thiamine hydrochloride. CONCLUSIONS: Abnormalities on DWI and ADC decrease became normalized with adequate therapy. The MRI abnormalities in WE might be owing to the "reversible cytotoxic edema" caused by vitamin B1 deficiency.

Aged↗
PubMed2002

Lesion patterns and mechanism of ischemia in internal carotid artery disease: a diffusion-weighted imaging study.

CONTEXT: Although embolism and low-flow phenomenon are the 2 main mechanisms of stroke in internal carotid artery (ICA) occlusive disease, the mechanism of border-zone infarction remains controversial. Diffusion-weighted imaging (DWI) can more easily detect small or multiple ischemic lesions than conventional imaging. OBJECTIVES: To investigate the ischemic lesion patterns on DWI and to discuss the mechanisms of stroke in ICA disease. DESIGN: Case series. SETTING: A tertiary referral center. PATIENTS: We enrolled 35 consecutive patients who had an acute ischemic stroke and (> or = 70%) stenosis or an occlusion of the extracranial ICA confirmed by cerebral angiography and an acute relevant stroke lesion on DWI within 1 week of onset, but without cardiac sources of embolism and tandem intracranial arterial disease. MAIN OUTCOME MEASURES: The lesion pattern on DWI was categorized as territorial or border zone. Multiple ischemic lesions were defined as noncontiguous lesions on DWI in more than 1 vascular territory. RESULTS: There were 3 distinctive stroke lesion patterns. (1) A territorial lesion without a border-zone lesion was found in 21 patients: superficial and superficial territorial in 9, superficial and deep territorial in 7, and single in 5. (2) A border-zone lesion with or without a territorial lesion was found in 10 patients: border zone and territorial in 9 and border zone alone in 1. (3) Bilateral hemispheric lesions were found in 4 patients. Multiple ischemic lesions were found in 29 (82.9%) of the 35 patients. No patient had episodes of hemodynamic compromise. CONCLUSIONS: An acute ischemic lesion in ICA occlusive disease is mainly multiple. Border-zone infarction was mostly associated with territorial infarction. These results support the fact that embolism is the predominant stroke mechanism in ICA occlusive disease.

Aged↗
PubMed2002

Diffusion-weighted and gradient echo magnetic resonance findings of hemichorea-hemiballismus associated with diabetic hyperglycemia: a hyperviscosity syndrome?

BACKGROUND: The magnetic resonance (MR) imaging findings of hemichorea-hemiballismus (HCHB) associated with hyperglycemia are characterized by hyperintensities in the striatum on T1-weighted MR images and computed tomographic scans, with a mechanism of petechial hemorrhage considered to be responsible. Diffusion-weighted MR imaging (DWI) has been reported to detect early ischemic damage (cytotoxic edema) as bright areas of high signal intensity and vasogenic edema as areas of heterogeneous signal intensity. We report various DWI findings in 2 patients with hyperglycemic HCHB. OBJECTIVES: To describe the DWI and gradient echo findings and characterize the types of edema in HCHB associated with hyperglycemia. SETTING: A tertiary referral center neurology department. DESIGN AND METHODS: Two patients with HCHB associated with hyperglycemia underwent DWI, gradient echo imaging, and conventional MR imaging with gadolinium enhancement. The patients had an elevated serum glucose level on admission and a long history of uncontrolled diabetes, and the symptoms were controlled by dopamine receptor blocking agents. Initial DWIs were obtained 5 to 20 days after symptom onset. Apparent diffusion coefficient (ADC) values were measured in the abnormal lesions with visual inspection of DWI and T2-weighted echo planar images. RESULTS: T1- and T2-weighted MR images and brain computed tomographic scans showed high signal intensities in the right head of the caudate nucleus and the putamen. Gradient echo images were normal. The DWIs showed bright high signal intensity in the corresponding lesions (patient 1), and the ADC values were decreased. The decrease in ADC and the high signal intensity on DWI persisted despite the disappearance of HCHB, even after 70 days. CONCLUSIONS: Gradient echo MR imaging findings were normal in HCHB with hyperglycemia, whereas DWI and the ADC map showed restricted diffusion, which suggests that hyperviscosity, not petechial hemorrhage, with cytotoxic edema can cause the observed MR abnormalities.

Aged↗
PubMed2002

Atypical brainstem encephalitis caused by herpes simplex virus 2.

BACKGROUND: Herpes simplex encephalitis is one of the most common and serious sporadic encephalitides of immunocompetent adults. Herpes simplex virus 2 (HSV-2) infections of the central nervous system usually manifest as subacute encephalitis, recurrent meningitis, myelitis, and forms resembling psychiatric syndromes. OBJECTIVES: To report and discuss magnetic resonance imaging (MRI) findings and clinical features in atypical brainstem encephalitis and facial palsy associated with HSV-2. SETTING: Neurology department of a tertiary referral center. PATIENT: A 37-year-old woman was admitted to the hospital with fever, diplopia, left hemiparesis, sensory change in the face and limbs, personality changes, frontal dysexecutive syndrome, and a stiff neck. Brain MRI showed multifocal high-signal intensities in the pons, midbrain, and frontal lobe white matter on T2-weighted and fluid-attenuated inversion recovery images. Cerebrospinal fluid (CSF) polymerase chain reaction (PCR) amplification analysis was positive for HSV-2. Acyclovir therapy was started, and the encephalitic symptoms disappeared with a negative conversion of HSV-2 PCR in the CSF. However, after the discontinuation of acyclovir therapy, peripheral facial palsy occurred on the left side. A possible relapse or delayed manifestation of the HSV-2 infection was suspected, and the acyclovir therapy was restarted. A complete remission was achieved 3 days after the treatment. She was discharged without any neurologic sequelae. CONCLUSIONS: We describe a patient who developed atypical encephalitis due to HSV-2 and peripheral facial palsy, which could also be related to the HSV-2. This case suggests that HSV-2 should be considered among the possible causes of atypical or brainstem encephalitis and that the PCR amplification method of the CSF can help reveal the possible cause of HSV-2.

Acyclovir↗
PubMedDate not supplied

Imaging of the ischemic penumbra in acute stroke.

One of the main reasons for the soaring interest in acute ischemic stroke among radiologists is the advent of new magnetic resonance techniques such as diffusion-weighted imaging. This new modality has prompted us to seek a better understanding of the pathophysiologic mechanisms of cerebral ischemia/infarction. The ischemic penumbra is an important concept and tissue region because this is the target of various recanalization treatments during the acute phase of stroke. In this context, it is high time for a thorough review of the concept, especially from the imaging point of view.

Brain↗